elastin and Aortic-Aneurysm--Abdominal

Abdominal aortic aneurysm (AAA) has a multifactorial etiology and the relevance of genetic factors is getting increasing interest, in particular those related to the destructive remodeling of extracellular matrix.. We performed a candidate gene association study of polymorphisms in genes coding matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMPs), and elastin (ELN) in AAA. DNA samples from 423 AAA patients and 423 controls were genotyped for 12 polymorphisms in 10 genes: MMP1 (-1607G/GG), MMP2 (-735C/T; -1306C/T; -1575 G/A), MMP3 (5A/6A), MMP9 (-1562C/T), MMP10 (A180G), MMP-12 (-82A/G), MMP-13 (-77A/G), TIMP1 (C434T), TIMP3 (-1296T/C), and ELN (G1355A).. Genotype distribution was significantly different between patients and controls for the following polymorphisms: -1306C/T MMP2; 5A/6A MMP3; -77A/G MMP-13; G1355A ELN; and C434T TIMP1. In a multivariable logistic regression analysis adjusted for traditional cardiovascular risk factors and chronic obstructive pulmonary disease, -1306C/T MMP2 (odds ratios [OR] = 0.55 [95% confidence interval, CI .34-.85], P < .007) and G1355A ELN (OR = 0.64 ([95% CI .41-.99], P = .046) polymorphisms resulted in independent protective factors for abdominal aortic aneurysm (AAA), whereas 5A/6A MMP3 (OR = 1.82 [95% CI 1.04-3.12], P = .034) and -77 A/G MMP-13 (OR = 2.14 [95% CI 1.18-3.86], P = .012) polymorphisms resulted in independent risk factors for AAA. In a multivariable logistic regression analysis adjusted for traditional cardiovascular factors and chronic obstructive pulmonary disease, the prevalence of the contemporary presence of three or four genetic risk conditions was a strong and independent determinant of AAA disease (OR = 2.96, 95% CI 1.67-5.24, P < .0001). For those polymorphisms independently associated with AAA in this study (-1306C/T MMP2, 5A/6A MMP3, -77A/G MMP-13, and G1355A ELN polymorphisms), we performed a meta-analysis of the available data (this paper and literature data). We found a significant association with an increased risk of AAA for MMP3 (AAA patients n = 1258, controls n = 1406: OR = 1.48 [95% CI = 1.23-1.78], I(2) = 0%) and MMP-13 (AAA patients n = 800, controls n = 843: OR = 1.37 [95% CI = 1.04-1.82], I(2) = 25%) polymorphisms and a trend that did not reach the statistical significance, toward a decreased risk of AAA for MMP2 (AAA patients n = 1090, controls n = 1077: OR = 0.83 [95% CI = .60-1.15], I(2) =7 1%) and ELN (AAA patients n = 904, controls n = 1069: OR = 0.79 [95% CI = .53-1.18], I(2) = 72%) polymorphisms.. These findings suggest that polymorphisms in MMP2, MMP3, MMP-13, and ELN genes may independently contribute to the pathogenesis of AAA.

Topics: Aortic Aneurysm, Abdominal; Case-Control Studies; Chi-Square Distribution; Elastin; Extracellular Matrix; Gene Frequency; Genetic Predisposition to Disease; Humans; Italy; Logistic Models; Matrix Metalloproteinase 13; Matrix Metalloproteinase 2; Matrix Metalloproteinase 3; Matrix Metalloproteinases; Odds Ratio; Phenotype; Polymorphism, Single Nucleotide; Risk Assessment; Risk Factors; Tissue Inhibitor of Metalloproteinases

Inflammation, proteolysis, smooth muscle cell apoptosis, and angiogenesis have been implicated in the pathogenesis of abdominal aortic aneurysms (AAAs), although the well-defined initiating mechanism is not fully understood. Matrix metalloproteinases (MMPs) such as MMP-2 and -9 and other proteinases degrading elastin and extracellular matrix are the critical pathogenesis of AAAs. Among the risk factors of AAAs, cigarette smoking is an irrefutable one. Cigarette smoke is practically involved in various aspects of the AAA pathogenesis. Nicotine, a major alkaloid in tobacco leaves and a primary component in cigarette smoke, can stimulate the MMPs expression by vascular SMCs, endothelial cells, and inflammatory cells in vascular wall and induce angiogenesis in the aneurysmal tissues. However, for the inflammatory and apoptotic processes in the pathogenesis of AAAs, nicotine seems to be moving in just the opposite direction. Additionally, the effects of nicotine are probably dose dependent or associated with the exposure duration and may be partly exerted by its receptors--nicotinic acetylcholine receptors (nAChRs). In this paper, we will mainly discuss the pathogenesis of AAAs involving inflammation, proteolysis, smooth muscle cell apoptosis and angiogenesis, and the roles of nicotine and nAChRs.

Topics: Aged; Aged, 80 and over; Animals; Aortic Aneurysm, Abdominal; Apoptosis; Elastin; Extracellular Matrix; Female; Humans; Hypertension; Inflammation; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice; Neovascularization, Pathologic; Nicotine; Receptors, Nicotinic; Risk Factors; Sex Factors; Smoking

Abdominal aortic aneurysms (AAAs) and abdominal wall hernias represent chronic degenerative conditions. Both aortic aneurysms and inguinal hernias share common epidemiologic features, and several investigators have found an increased propensity for hernia development in patients treated for aortic aneurysms. Chronic inflammation and dysregulation in connective tissue metabolism constitute underlying biological processes, whereas genetic influences appear to be independently associated with both disease states. A literature review was conducted to identify all published evidence correlating aneurysms and hernias to a common pathology.. PubMed/Medline was searched for studies investigating the clinical, biochemical, and genetic associations of AAAs and abdominal wall hernias. The literature was searched using the MeSH terms "aortic aneurysm, abdominal," "hernia, inguinal," "hernia, ventral," "collagen," "connective tissue," "matrix metalloproteinases," and "genetics" in all possible combinations. An evaluation, analysis, and critical overview of current clinical data and pathogenic mechanisms suggesting an association between aneurysms and hernias were undertaken.. Ample evidence lending support to the clinical correlation between AAAs and abdominal wall hernias exists. Pooled analysis demonstrated that patients undergoing aortic aneurysm repair through a midline abdominal incision have a 2.9-fold increased risk of developing a postoperative incisional hernia compared with patients treated for aortoiliac occlusive disease (odds ratio, 2.86; 95% confidence interval, 1.97-4.16; P < .00001), whereas the risk of inguinal hernia was 2.3 (odds ratio, 2.30; 95% confidence interval, 1.52-3.48; P < .0001). Emerging evidence has identified inguinal hernia as an independent risk factor for aneurysm development. Although mechanisms of extracellular matrix remodeling and the imbalance between connective tissue degrading enzymes and their inhibitors instigating inflammatory responses have separately been described for both disease states, comparative studies investigating these biological processes in aneurysm and hernia populations are scarce. A genetic predisposition has been documented in familial and observational segregation studies; however, the pertinent literature lacks sufficient supporting evidence for a common genetic basis for aneurysm and hernia.. Insufficient data are currently available to support a systemic connective tissue defect affecting the structural integrity of the aortic and abdominal wall. Future investigations may elucidate obscure aspects of aneurysm and hernia pathophysiology and create novel targets for pharmaceutical and gene strategies for disease prevention and treatment.

Topics: Aortic Aneurysm, Abdominal; Collagen; Connective Tissue Diseases; Elastin; Genetic Predisposition to Disease; Hernia, Abdominal; Hernia, Inguinal; Humans; Matrix Metalloproteinases; Odds Ratio; Risk Assessment; Risk Factors; Vascular Surgical Procedures

The maximal diameter of abdominal aortic aneurysms (AAAs) is the dominating indication for repair. However half of the AAAs repaired would never have ruptured if left unrepaired, although small AAAs occasionally rupture. Earlier surgery may be associated with a lower mortality. More precise indicators for surgery are warranted. This systematic review identifies potential systemic biomarkers for AAA rupture or expansion.. MEDLINE/PubMed and EMBASE (from 1985 trough May 2007) were searched with the medical subject heading abdominal aortic aneurysm and keywords "size", "progression" or "growth" or "expansion rate" or "rupture" on the basis of MESH tree and as a text search restricted to English, German, French and Italian. In addition, reference lists were studied and manual searches performed. Observational studies investigating the association of circulating biomarkers with AAA rupture, expansion or size were selected.. Two reviewers (SU and GU) independently extracted the following data: year of publication, study characteristics, duration of follow-up, circulating biomarker, AAA expansion rate or size or rupture.. 699 papers were identified. After exclusion of thoracic aneurysms and cardiac studies (n=118), surgical or medical treatment studies (n=179), case reports and animal studies (n=87), as well as reviews or letters (n=66), 249 articles were selected. Also excluded were 230 papers that did not report AAA size, expansion rate or rupture. 39 papers were included. Several potential biomarkers were identified. The strongest association with AAA was obtained with serum elastin peptides (SEP) and plasmin-antiplasmin (PAP) complexes. Matrix-degrading metalloproteinase 9 (MMP9) and interferon-gamma (IFN-gamma) could have clinical potential while many putative biomarkers showed poor association.. Several circulating agents in peripheral blood may predict AAA size, expansion rate or rupture. Few of them have clinical potential for future use. Confirmative studies and development of multivariate models are needed, together with continuing search for new biomarkers using the discovery based sciences within proteomics and/or genomics.

Topics: alpha-2-Antiplasmin; Aortic Aneurysm, Abdominal; Aortic Rupture; Biomarkers; Disease Progression; Elastin; Fibrinolysin; Humans; Interferon-gamma; Matrix Metalloproteinase 9; Peptides; Predictive Value of Tests

Abdominal aortic aneurysms and their management remain a significant health problem that is likely to assume greater importance with the expansion of the elderly population. Elastin fibres degradation and extracellular matrix remodelling seems to be the basic process in aneurysm formation. Recent investigations revealed the principal role of elastin-laminin receptor in extracellular matrix remodelling in aging and atherosclerosis. The correlation between events observed in animal aneurysm models, human aneurysms and in experiments on elastin-laminin receptor properties was discussed to propose the hypothesis about the role of elastin peptides and elastin-laminin receptor in aortic aneurysm formation.

Topics: Aging; Animals; Aortic Aneurysm, Abdominal; Arteriosclerosis; Elastin; Extracellular Matrix; Humans; Receptors, Cell Surface; Receptors, Laminin

Topics: Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Diseases; Aortic Rupture; Arteriosclerosis; Collagen; Elastin; Humans; Metalloendopeptidases

Abdominal aortic aneurysms have usually been characterized as atheroslcerotic, but this view of their pathogenesis is a restricted one. As yet, no unified concept of pathogenesis has emerged, bat several factors appear to have an important role, including familial clustering, genetically determined and acquired biochemical alterations in the structural matrix of the aortic wall and bemodynamic mechanical factors. We review literature data concerning new pathogenic concepts of abdominal aortic aneurysms and particularly familial predisposition. Ultrasonographic screening is recommended in brothers (50 years) of patients with aneurysms of the abdominal aorta.

Topics: Aortic Aneurysm, Abdominal; Elastin; Genetic Diseases, Inborn; Humans

To date, aneurysm research has been primarily descriptive, reiterating the complex nature of the disease process. Enhanced by the convergence of matrix biochemistry, cell biology and immunology, this work is providing important new insight into how matrix metabolism is regulated in the diseased aorta. The focus is now on the inflammatory process and its regulation of the matrix remodeling which occurs with abdominal aortic aneurysm. A family of matrix-degrading enzymes appear to have a central role in this process. As we have learned from the evolution of the treatment of other pathologic processes such as peptic ulcer disease, the most effective pharmacologic therapies are designed from a thorough understanding of the pathophysiology of the disease. We are quickly moving forward in formulating a comprehensive understanding of the various complex interactions that result in the formation of aortic aneurysm. Given the progress of the past decade, we can expect the identification of aneurysm-associated genes and clinical trials of anti-inflammatory medications and protease inhibitors as we enter the 21st century.

Topics: Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortitis; Collagen; Elastin; Extracellular Matrix; Humans; Metalloendopeptidases; Muscle, Smooth, Vascular

Topics: Aged; Aortic Aneurysm, Abdominal; Chromosome Mapping; Collagen; Diseases in Twins; Elastin; Extracellular Matrix Proteins; Female; Fibrillins; Humans; Male; Metalloendopeptidases; Microfilament Proteins; Middle Aged; Nuclear Family

Topics: Administration, Topical; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Rupture; Biomechanical Phenomena; Blood Pressure; Collagen; Dogs; Elastic Tissue; Elastin; Humans; Microscopy, Electron, Scanning; Pancreatic Elastase; Rabbits; Stress, Mechanical

Topics: Aging; Aorta; Aortic Aneurysm, Abdominal; Arteriosclerosis; DNA, Complementary; Elastic Tissue; Elastin; Enzyme Induction; Humans; Leukocyte Elastase; Neutrophils; RNA, Messenger; Serine Endopeptidases

Past concepts of aneurysmal dilatation as a passive process of attenuation are oversimplified and inaccurate. Aneurysm formation is a complex remodeling process that involves both synthesis and degradation of matrix proteins. Interstitial procollagen gene expression is increased in AAA compared to AOD or normal aorta, whereas tropoelastin gene expression is decreased in both AOD and AAA. The medial elastin network is disrupted and discontinuous in small AAA. Thus, the growth rate of an established AAA may well relate to the balance between collagen synthesis and degradation. Although the increased procollagen expression found in AAA may represent a compensatory response, understanding the factors that modulate matrix metabolism in AAA may allow for development of pharmacologic strategies which effectively inhibit the growth of small aneurysms.

Topics: Animals; Aorta; Aortic Aneurysm, Abdominal; Aortitis; Arteriosclerosis; Cattle; Collagen; Elastin; Extracellular Matrix Proteins; Humans; Platelet-Derived Growth Factor; RNA, Messenger; Tensile Strength

Topics: Aortic Aneurysm, Abdominal; Arteriosclerosis; Collagen; Elastin; Humans; Prevalence

We now know our past concepts of AAA pathogenesis to be oversimplified and inaccurate. In fact, the metabolic activity of the aneurysm wall is markedly increased in comparison with normal aorta. It has become clear that AAAs result not from passive dilatation, but from a complex remodeling process involving both the synthesis and degradation of matrix proteins. Our understanding of this process has been advanced by applying molecular biology techniques. Although elastin fragmentation and medial attenuation remain the most striking histological features of AAA tissue, experimental and clinical evidence suggests that the adventitia, which is predominantly collagen, is capable of maintaining the dimensional stability of the aorta in the absence of the medial elastin network. Thus, although factors that result in fragmentation and attenuation of elastin may be important in the etiology of AAA, factors regulating the balance of collagen synthesis and degradation likely determine the rate of AAA progression. The resident inflammatory cells in AAA undoubtedly play an important pathological role in aortic dilatation. Thus, understanding the interaction between aortic mesenchymal cells (smooth muscle cells and fibroblasts) and inflammatory cells (lymphocytes and macrophages) should allow for the identification of genetic factors that predispose to AAA. In addition to the possibility of early identification of patients at risk for AAA, new insights into AAA pathogenesis might allow for development of pharmacological strategies for inhibiting expansion of small AAA.

Topics: Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortitis; Arteriosclerosis; Collagen; Elastin; Endopeptidases; Extracellular Matrix Proteins; Humans

The etiology of infrarenal, "nonspecific" aortic aneurysms was previously believed to be degenerative arteriosclerosis, but recent studies of the components of the aortic wall have shown that complicated disturbances primarily concerning the synthesis and degradation of elastin and collagen are major pathogenetic components. Non-invasive measurements of the biomechanical properties of the aneurysms and determinations of the directions and forces of local flow velocity vectors within the aneurysmatic sac have provided new knowledge of the abnormal physical factors that follow dilatation. Detailed studies on the biochemical and physiological factors will make it possible to identify patients at risk and provide the foundations for interventions that will prevent development of the disease.

Topics: Aortic Aneurysm, Abdominal; Biomechanical Phenomena; Blood Flow Velocity; Collagen; Elastin; Humans; Muscle, Smooth, Vascular; Renal Artery

The pathogenesis of abdominal aortic aneurysm involves many factors acting over time. However, destruction of elastin in the aortic wall is a key event that shifts the load produced by blood pressure on to collagen. This is exacerbated in the presence of hypertension. Smoking and age are further important factors, as is the site; elastic lamellae are relatively less common in the abdominal aorta. Once the shielding effect of elastin is lost, further dilatation and rupture of the aorta depend on the physical properties of the collagen present.

Topics: Age Factors; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Arteriosclerosis; Collagen; Elastin; Humans; Hypertension; Inflammation; Smoking

Patients with abdominal aortic aneurysms (AAAs) exhibit arterial dilation and altered matrix composition throughout the vasculature. Matrix metalloproteinase-2 (MMP-2) is the dominant elastase in small AAAs, and overexpression of MMP-2 in vascular smooth muscle cells (SMCs) may be a primary etiological event in aneurysm genesis. The aim of this study was to investigate MMP-2 production in vascular tissue remote from the abdominal aorta.. Inferior mesenteric vein (IMV) was harvested from patients undergoing aneurysm repair (n=21) or colectomy for diverticular disease (n=13, control). Matrix composition of the vessels was determined by stereological techniques. MMPs were extracted from tissue homogenates and quantified by gelatin zymography and ELISA. MMP-2, membrane type-1 MMP (MT1-MMP), and tissue inhibitor of metalloproteinases type 2 (TIMP-2) expression were determined by Northern analysis. SMCs were isolated from IMV, and the production and expression of MMP-2 and TIMP-2 in the SMC lines were quantified. Tissue homogenates and isolated inferior mesenteric SMCs from patients with aneurysms demonstrated significantly elevated MMP-2 levels, with no difference in TIMP-2 or MT1-MMP. These differences were a result of increased MMP-2 expression. Histological examination revealed fragmentation of elastin fibers within venous tissue obtained from patients with AAA and a significant depletion of the elastin within the media. In situ zymography localized elastolysis to medial SMCs.. Patients with AAA have elevated MMP-2 levels in the vasculature remote from the aorta. This finding is due to increased MMP-2 expression from SMCs, a characteristic maintained in tissue culture. These data support both the systemic nature of aneurysmal disease and a primary role of MMP-2 in aneurysm formation.

Topics: Aged; Aged, 80 and over; Aortic Aneurysm, Abdominal; Blotting, Northern; Cells, Cultured; Elastin; Enzyme-Linked Immunosorbent Assay; Female; Humans; Immunohistochemistry; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinases, Membrane-Associated; Mesenteric Veins; Metalloendopeptidases; Middle Aged; Muscle, Smooth, Vascular; RNA, Messenger; Tissue Inhibitor of Metalloproteinase-2

Medical therapeutic options to prevent rupture of abdominal aortic aneurysm (AAA), a critical event, must be developed. Moreover, further understanding of the process of AAA development and rupture is crucial. Previous studies have revealed that aortic hypoperfusion can induce the development of AAA, and we successfully developed a hypoperfusion-induced AAA animal model. In this study, we examined the effects of medium-chain triglycerides (MCTs), tricaprylin (C8-TG) and tricaprin (C10-TG), on hypoperfusion-induced AAA rat model. We estimated the effects of MCTs on aortic pathologies, mechanical properties of the aorta, and development of AAA. C10-TG, but not C8-TG, significantly suppressed AAA development and completely prevented the rupture. We observed that C10-TG prevented the development and rupture of AAA, but not C8-TG. Additionally, regression of AAA diameter was observed in the C10-TG group. Pathological analysis revealed C10-TG improved the hypoperfusion-induced increase in hypoxia-inducible factor-1α levels, medial smooth muscle cells (SMCs) loss, degeneration of aortic elastin and collagen fibers, and loss of aortic wall elasticity. In addition, regression of the formed AAA was observed by administration of C10-TG after AAA formation. C10-TG administration after AAA formation improved degeneration of AAA wall including degradation of aortic elastin and collagen fibers, stenosis of vasa vasorum, and loss of medial SMCs. These data suggest C10-TG can prevent AAA by attenuating aortic hypoperfusion and degeneration. Considering the clinical safety of C10-TG, C10-TG can be a promising AAA drug candidate.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Collagen; Disease Models, Animal; Elastin; Rats; Triglycerides

For decades, numerous experimental animal models have been developed to examine the pathophysiologic mechanisms and potential treatments for abdominal aortic aneurysms (AAAs) in diverse species with varying chemical or surgical approaches. This study aimed to create an AAA mouse model by the periarterial incubation with papain, which can mimic human AAA with advantages such as simplicity, convenience, and high efficiency. Eighty C57BL/6J male mice were randomly assigned to 1 of the 4 groups: papain (1.0 or 2.0 mg), porcine pancreatic elastase, and phosphate-buffered solution. The aortic segment was wrapped for 20 minutes, and the diameter was measured using ultrasound preoperatively and postoperative days 7 and 14. Then, the mice were killed for histomorphometric and immunohistochemical analyses. According to ultrasound measurements and histomorphometric analyses, on postoperative day 7, 65% of mice in the 1.0-mg papain group and 60% of mice in the 2.0-mg papain group developed AAA. In both papain groups, 100% of mice developed AAA, and 65% of mice in the porcine pancreatic elastase group developed AAA on postoperative day 14. Furthermore, hematoxylin/eosin, elastin van Gieson, and Masson staining of tissues from the papain group revealed thickened media and intimal hyperplasia, collagen sediments, and elastin destruction, indicating that AAA histochemical alteration was similar to that of humans. In addition, the immunohistochemical analysis was conducted to detect infiltrated inflammatory cells, such as macrophages and leukocytes, in the aortic wall and hyperplasic adventitia. The expression of matrix metalloproteinase 2 and 9 was significantly upregulated in papain and human AAA tissues. Periarterial incubation with 1.0 mg of papain for 20 minutes can successfully create an experimental AAA model in mice for 14 days, which can be used to explore the mechanism and treatment of human AAA.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elastin; Humans; Male; Matrix Metalloproteinase 2; Mice; Mice, Inbred C57BL; Pancreatic Elastase; Papain; Swine

Abdominal aortic aneurysm (AAA) is a multifactorial cardiovascular disease with a high risk of death, and it occurs in the infrarenal aorta with vascular dilatation. High blood pressure acts on the aortic wall, resulting in rupture and causing life-threatening intra-abdominal hemorrhage. Vascular smooth muscle cell (VSMC) dysregulation and extracellular matrix (ECM) degradation, especially elastin breaks, contribute to structural changes in the aortic wall. The pathogenesis of AAA includes the occurrence of oxidative stress, inflammatory cell infiltration, elastic fiber fragmentation, VSMC apoptosis, and phenotypic transformation. Tributyrin (TB) is decomposed by intestinal lipase and has a function similar to that of butyrate. Whether TB has a protective effect against AAA remains uncertain. In the present study, we established an AAA murine model by angiotensin II (AngII) induction in low-density lipoprotein receptor knockout (

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elastin; Epigenesis, Genetic; Humans; Mice; Mice, Inbred C57BL; Mice, Knockout

C-reactive protein (CRP) levels are elevated in patients with abdominal aortic aneurysms (AAA). However, it has not been investigated whether CRP contributes to AAA pathogenesis.. CRP deficient and wild type (WT) male mice were subjected to AAA induction via transient intra-aortic infusion of porcine pancreatic elastase. AAAs were monitored by. CRP protein levels were higher in aneurysmal than that in non-aneurysmal aortas. Aneurysmal aortic dilation was markedly suppressed in CRP deficient (aortic diameter: 1.08 ± 0.11 mm) as compared to WT (1.21 ± 0.08 mm) mice on day 14 after elastase infusion. More medial elastin was retained in CRP deficient than in WT elastase-infused mice. Macrophage accumulation was significantly less in aneurysmal aorta from CRP deficient than that from WT mice. Matrix metalloproteinase 2 expression was also attenuated in CRP deficient as compared to WT aneurysmal aortas. CRP deficiency had no recognizable influence on medial smooth muscle loss, lymphocyte accumulation, aneurysmal angiogenesis, and matrix metalloproteinase 9 expression. In. CRP deficiency suppressed experimental AAAs by attenuating aneurysmal elastin destruction, macrophage accumulation and matrix metalloproteinase 2 expression.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; C-Reactive Protein; Elastin; Humans; Male; Matrix Metalloproteinase 2; Mice; Swine

We aimed to investigate the formation and self-healing process of rabbit abdominal aortic aneurysm (AAA) by focus on the degeneration and regeneration of smooth muscle cells (SMCs) in elastase-induced AAA model and enlarging AAA model in rabbits.. Sixty rabbits were equally divided into 2 aneurysm groups (Group A and Group B). Rabbits received a 10-min incubation of elastase in Group A (10 units/µL) and Group B (1 unit/µL). Rabbits underwent aortic stenosis above the incubated segment in Group B. Aortic diameter was measured and rabbits were sacrificed for histopathological and immunohistochemical studies.. The incubated aorta dilated immediately and ran up to maxima by day 21 in Group A. All aneurysms formed by day 21 and enlarged progressively in Group B. SMCs content, elastin content and intima-media thickness decreased significantly by day 0 in Group A. SMCs and elastic fibers were destroyed gradually in Group B, however, SMCs content was significantly lower than Group A by day 70. Intimal thickness increased significantly by day 70 in the Aneurysm groups. MMP2 maintained moderate expression in Group A, which decreased significantly by day 3 in Group B. MMP9 and RAM11 expressions were higher by day 1, but decreased significantly by day 3 in Group B.. Irreversible degeneration of SMCs is critical to a rapid formation of elastase-induced rabbit AAA model, and SMCs excessive regeneration accounts for the selfhealing process. SMCs degradation and regeneration remain relatively stable in an enlarging AAA model. SMCs should be the key target for studying the mechanism of AAA and intervention therapy.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Dilatation, Pathologic; Disease Models, Animal; Elastic Tissue; Elastin; Ligation; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Pancreatic Elastase; Rabbits; Regeneration; Time Factors; Vascular Remodeling

Interferon-stimulated gene 15 (ISG15) encodes a ubiquitin-like protein that induces a reversible post-translational modification (ISGylation) and can also be secreted as a free form. ISG15 plays an essential role as host-defence response to microbial infection; however, its contribution to vascular damage associated with hypertension is unknown.. Bioinformatics identified ISG15 as a mediator of hypertension-associated vascular damage. ISG15 expression positively correlated with systolic and diastolic blood pressure and carotid intima-media thickness in human peripheral blood mononuclear cells. Consistently, Isg15 expression was enhanced in aorta from hypertension models and in angiotensin II (AngII)-treated vascular cells and macrophages. Proteomics revealed differential expression of proteins implicated in cardiovascular function, extracellular matrix and remodelling, and vascular redox state in aorta from AngII-infused ISG15-/- mice. Moreover, ISG15-/- mice were protected against AngII-induced hypertension, vascular stiffness, elastin remodelling, endothelial dysfunction, and expression of inflammatory and oxidative stress markers. Conversely, mice with excessive ISGylation (USP18C61A) show enhanced AngII-induced hypertension, vascular fibrosis, inflammation and reactive oxygen species (ROS) generation along with elastin breaks, aortic dilation, and rupture. Accordingly, human and murine abdominal aortic aneurysms showed augmented ISG15 expression. Mechanistically, ISG15 induces vascular ROS production, while antioxidant treatment prevented ISG15-induced endothelial dysfunction and vascular remodelling.. ISG15 is a novel mediator of vascular damage in hypertension through oxidative stress and inflammation.

Topics: Angiotensin II; Animals; Aortic Aneurysm, Abdominal; Carotid Intima-Media Thickness; Elastin; Humans; Hypertension; Inflammation; Interferons; Leukocytes, Mononuclear; Mice; Mice, Inbred C57BL; Oxidation-Reduction; Oxidative Stress; Reactive Oxygen Species

Background cGMP-hydrolyzing phosphodiesterase type 5 (PDE5) regulates vascular smooth muscle cell (SMC) contraction by antagonizing cGMP-dependent protein kinase I (PKGI)-dependent SMC relaxation. SMC contractile dysfunction is implicated in the pathogenesis of aortic aneurysm. PDE5 inhibitors have been used for treating erectile dysfunction, such as drug Viagra (sildenafil). However, a few clinical cases have reported the association of Viagra usage with aortic dissection, and reduced PDE5A expression was found in human aortic aneurysm tissues. Therefore, we aimed to investigate the effect of sildenafil on experimental abdominal aortic aneurysm (AAA), the most common form of aortic aneurysm in elderly men. Methods and Results AAA was induced in C57BL/6J male mice by periaortic elastase in combination with blocking elastin/collagen formation via 3-aminopropionitrile fumarate salt for 35 days. PDE5A protein levels detected by immunostaining were significantly reduced in mouse AAA. Sildenafil application in drinking water significantly aggravated aortic wall dilation and elastin degradation with pre-existing moderate AAA. The phosphorylation level of myosin light chain 2 at Ser19, a biochemical marker of SMC contraction, was significantly reduced by sildenafil in AAA. Proximity ligation assay further revealed that the interaction between cGMP and PKGI was significantly increased by sildenafil in AAA, suggesting an elevation of PKGI activation in AAA. Conclusions Sildenafil treatment aggravated the degradation of elastin fibers and progression of experimental AAA by dysregulating cGMP and contractile signaling in SMCs. Our findings may raise the caution of clinical usage of Viagra in aneurysmal patients.

Topics: Aged; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elastin; Humans; Male; Mice; Mice, Inbred C57BL; Sildenafil Citrate

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Elastin; Female; Male; Matrix Metalloproteinase 2; Nanofibers; Peptides; Rats; Rats, Sprague-Dawley

Interleukin-1 (IL-1) signaling has an established role as a cytokine signaling pathway important for progression of abdominal aortic aneurysms (AAAs). While the IL-1β ligand and IL-1R1 have been previously investigated, the role of the IL-1α ligand in AAAs remains unknown. In this study, we sought to examine the role of IL-1α in AAAs using genetic and pharmacologic approaches.. Eight-week-old wild-type (WT) or IL-1α knock-out (KO) male and female mice (n = 10-16/group) underwent experimental AAA and were harvested 14 days following surgery to assess AAA size and characteristics. In separate studies, 8-week-old WT mice were treated with an inhibitor to IL-1α during AAA formation and harvested 14 days following surgery. Finally, WT and IL-1α KO mice were administered Anakinra, an IL-R1 inhibitor, during AAA formation to determine the effect of inhibiting IL-1R1 when IL-1α is knocked out.. Male and female IL-1α KO mice had larger AAAs compared to WT AAAs (male: 153% vs. 89.2%, P = 0.0001; female: 86.6% vs. 63.5%, P = 0.02). IL-1α KO mice had greater elastin breakage (P = 0.01), increased levels of macrophage staining (P = 0.0045), and greater pro-metallo proteinase 2 (P = 0.02). Pharmacologic inhibition of WT male mice with an IL-1α neutralizing antibody resulted in larger AAAs (133.1% vs. 77.0%, P < 0.001). Finally, treatment of IL-1α KO male mice with Anakinra decreased AAA formation compared with vehicle control AAAs (Anakinra + IL-1α KO: 47.7% vs. WT: 147.1%; P = 0.0001).. IL-1α disruption using either genetic or pharmacologic approaches worsens AAAs.

Topics: Animals; Antibodies, Neutralizing; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elastin; Female; Interleukin 1 Receptor Antagonist Protein; Interleukin-1alpha; Ligands; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Peptide Hydrolases; Treatment Outcome

Abdominal aortic aneurysms (AAAs) are localized rupture-prone expansions of the aorta with limited reversibility that develop due to proteolysis of the elastic matrix. Natural regenerative repair of an elastic matrix is difficult due to the intrinsically poor elastogenicity of adult vascular smooth muscle cells (VSMCs). This justifies the need to provide external, pro-elastin regenerative- and anti-proteolytic stimuli to VSMCs in the AAA wall towards reinstating matrix structure in the aorta wall. Introducing alternative phenotypes of highly elastogenic and contractile cells into the AAA wall capable of providing such cues, proffers attractive prospects for AAA treatment. In this regard, we have previously demonstrated the superior elastogenicity of bone marrow mesenchymal stem cell (BM-MSC)-derived SMCs (cBM-SMCs) and their ability to provide pro-elastogenic and anti-proteolytic stimuli to aneurysmal SMCs in vitro. However, the major issues associated with cell therapy, such as their natural ability to home into the AAA tissue, their in vivo biodistribution and retention in the AAA wall, and possible paracrine effects on AAA tissue repair processes in the event of localization in remote tissues remain uncertain. Therefore, in this study we focused on assessing the fate, safety, and AAA reparative effects of BM-MSC-derived cBM-SMCs in vivo. Our results indicate that the cBM-SMCs (a) possess natural homing abilities similar to the undifferentiated BM-MSCs, (b) exhibit higher retention upon localization in the aneurysmal aorta than BM-MSCs, (c) downregulate the expression of several inflammatory and pro-apoptotic cytokines that are upregulated in the AAA wall contributing to accelerated elastic matrix breakdown and suppression of elastic fiber neo-assembly, repair, and crosslinking, and (d) improve elastic matrix content and structure in the AAA wall toward slowing the growth of AAAs. Our study provides initial evidence of the in vivo elastic matrix reparative benefits of cBM-SMCs and their utility in cell therapy to reverse the pathophysiology of AAAs.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Elastin; Extracellular Matrix; Homeostasis; Mesenchymal Stem Cells; Myocytes, Smooth Muscle; Rats; Rats, Sprague-Dawley; Tissue Distribution

MT1-MMP (membrane-type 1 matrix metalloproteinase, MMP-14) is a transmembrane-anchored protein with an extracellular proteinase domain and a cytoplasmic tail devoid of proteolytic functions but capable of mediating intracellular signaling that regulates tissue homeostasis. MT1-MMP extracellular proteolytic activity has been shown to regulate pathological remodeling in aortic aneurysm and atherosclerosis. However, the role of the nonproteolytic intracellular domain of MT1-MMP in vascular remodeling in abdominal aortic aneurysms (AAA) is unknown.. We generated a mutant mouse that harbors a point mutation (Y573D) in the MT1-MMP cytoplasmic domain that abrogates the MT1-MMP signaling function without affecting its proteolytic activity. These mice and their control wild-type littermates were subjected to experimental AAA modeled by angiotensin II infusion combined with PCSK9 (proprotein convertase subtilisin/kexin type 9) overexpression and high-cholesterol feeding.. The mutant mice developed more severe AAA than the control mice, with concomitant generation of intraaneurysmal atherosclerotic lesions and dramatically increased macrophage infiltration and elastin degradation. Aortic lesion-associated and bone marrow-derived macrophages from the mutant mice exhibited an enhanced inflammatory state and expressed elevated levels of proinflammatory Netrin-1, a protein previously demonstrated to promote both atherosclerosis and AAA.. Our findings show that the cytoplasmic domain of MT1-MMP safeguards from AAA and atherosclerotic plaque development through a proteolysis-independent signaling mechanism associated with Netrin-1 expression. This unexpected function of MT1-MMP unveils a novel mechanism of synchronous onset of AAA and atherogenesis and highlights its importance in the control of vascular wall homeostasis.

Topics: Angiotensin II; Animals; Aortic Aneurysm, Abdominal; Atherosclerosis; Cholesterol; Elastin; Matrix Metalloproteinase 14; Mice; Netrin-1; Proprotein Convertase 9; Subtilisins

In vivo angiotensin II (AngII)-treatment is a widely used experimental model to induce cardiovascular disease and results in a high likelihood of abdominal aorta aneurysm (AAA) formation. This involves progressive and irreversible focal dilation of the abdominal aorta and induces adverse aortic connective tissue remodeling contributing to aortic wall stiffening through inflammation, elastin degradation, and collagen restructuring. Hence, the present study aimed to investigate how AAA formation in AngII-treated mice affects aortic function and biomechanics. To this end, C57Bl/6J mice were treated with AngII (1000 ng/[kg.min]) or PBS infusion for 28 days. Peripheral blood pressure, echocardiography, and aortic pulse wave velocity were measured in vivo. Thoracic aorta rings were studied ex vivo in organ chambers, while aortic vascular smooth muscle cell (VSMC) phenotype was investigated histologically. We confirmed peripheral hypertension, cardiac hypertrophy, aortic stiffening, and increased VSMC proliferation and migration after AngII-treatment. Abdominal aorta aneurysm formation was observed in 8/13 AngII-treated mice. Ex vivo thoracic aortic rings of both aneurysmal and non-aneurysmal AngII-treated mice showed high isobaric aortic stiffness, endothelial dysfunction, heightened α

Topics: Adrenergic Agents; Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Collagen; Elastin; Mice; Mice, Inbred C57BL; Pulse Wave Analysis

Abdominal aortic aneurysm (AAA) represents the serious vascular degenerative disorder, which causes high incidence and mortality. Alpha-ketoglutarate (AKG), a crucial metabolite in the tricarboxylic acid (TCA) cycle, has been reported to exert significant actions on the oxidative stress and inflammation. However, its role in AAA still remains elusive. Herein, we examined the effects of AKG on the formation of AAA. The study established an elastase-induced mouse abdominal aortic aneurysms model as well as a TNF-α-mediated vascular smooth muscle cells (VSMCs) model, respectively. We displayed that AKG pre-treatment remarkably prevented aneurysmal dilation assessed by diameter and volume and reduced aortic rupture. In addition, it was also observed that AKG treatment suppressed the development of AAA by attenuating the macrophage infiltration, elastin degradation and collagen fibers remodeling. In vitro, AKG potently decreased TNF-α-induced inflammatory cytokines overproduction, more apoptotic cells and excessive superoxide. Mechanistically, we discovered that upregulation of vpo1 in AAA was significantly suppressed by AKG treatment. By exploring the RNA-seq data, we found that AKG ameliorates AAA mostly though inhibiting oxidative stress and the inflammatory response. PXDN overexpression neutralized the inhibitory effects of AKG on ROS generation and inflammatory reaction in MOVAS. Furthermore, AKG treatment suppressed the expression of p-ERK1/2, 3-Cl Tyr in vivo and in vitro. ERK activator disrupted the protective of AKG on TNF-α-induced VSMCs phenotypic switch. Conclusively, AKG can serve as a beneficial therapy for AAA through regulating PXDN/HOCL/ERK signaling pathways.

Topics: Animals; Aortic Aneurysm, Abdominal; Collagen; Cytokines; Deoxyribonucleosides; Disease Models, Animal; Elastin; Inflammation; Ketoglutaric Acids; MAP Kinase Signaling System; Mice; Mice, Inbred C57BL; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Pancreatic Elastase; Purine Nucleosides; Reactive Oxygen Species; Signal Transduction; Superoxides; Tricarboxylic Acids; Tumor Necrosis Factor-alpha

Type I interferon receptor signaling contributes to several autoimmune and vascular diseases such as lupus, atherosclerosis and stroke. The purpose of this study was to assess the influence of type I interferon receptor deficiency on the formation and progression of experimental abdominal aortic aneurysms (AAAs).. AAAs were induced in type I interferon receptor subunit 1 (IFNAR1)-deficient and wild type control male mice via intra-infrarenal aortic infusion of porcine pancreatic elastase. Immunostaining for IFNAR1 was evaluated in experimental and clinical aneurysmal abdominal aortae. The initiation and progression of experimental AAAs were assessed via ultrasound imaging prior to (day 0) and days 3, 7 and 14 following elastase infusion. Aneurysmal histopathology was analyzed at sacrifice.. Increased aortic medial and adventitial IFNAR1 expression was present in both clinical AAAs harvested at surgery and experimental AAAs. Following AAA induction, wild type mice experienced progressive, time-dependent infrarenal aortic enlargement. This progression was substantially attenuated in IFNAR1-deficient mice. On histological analyses, medial elastin degradation, smooth muscle cell depletion, leukocyte accumulation and neoangiogenesis were markedly diminished in IFNAR1-deficient mice in comparison to wild type mice.. IFNAR1 deficiency limited experimental AAA progression in response to intra-aortic elastase infusion. Combined with clinical observations, these results suggest an important role for IFNAR1 activity in AAA pathogenesis.

Topics: Animals; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elastin; Male; Mice; Mice, Inbred C57BL; Pancreatic Elastase; Receptor, Interferon alpha-beta; Swine

Abdominal aortic aneurysm (AAA) is a significant medical problem with a high mortality rate. Nevertheless, the underlying mechanism for the progression and regression of AAA is unknown.. Experimental model of AAA was first created by porcine pancreatic elastase incubation around the infrarenal aorta of C57BL/6 mice. Then, AAA progression and regression were evaluated based on the diameter and volume of AAA. The aortas were harvested for hematoxylin-eosin staining (HE), orcein staining, sirius red staining, immunofluorescence analysis and perls' prussian blue staining at the indicated time point. Finally, β-aminopropionitrile monofumarate (BAPN) was used to explore the underlying mechanism of the regression of AAA.. When we extended the observation period to 100 days, we not only observed an increase in the AAA diameter and volume in the early stage, but also a decrease in the late stage. Consistent with AAA diameter and volume, the aortic thickness showed the same tendency based on HE staining. The elastin and collagen content first degraded and then regenerated, which corresponds to the early deterioration and late regression of AAA. Then, endogenous up-regulation of lysyl oxidase (LOX) was detected, accompanying the regression of AAA, as detected by an immunofluorescent assay. BAPN and LOX inhibitor considerably inhibited the regression of AAA, paralleling the degradation of elastin lamella and collagen.. Taken together, we tentatively conclude that endogenous re-generation of LOX played an influential role in the regression of AAA. Therefore, regulatory factors on the generation of LOX exhibit promising therapeutic potential against AAA.

Topics: Aminopropionitrile; Animals; Aortic Aneurysm, Abdominal; Collagen; Disease Models, Animal; Disease Progression; Elastin; Extracellular Matrix Proteins; Mice; Mice, Inbred C57BL; Pancreatic Elastase; Protein-Lysine 6-Oxidase; Up-Regulation

Women are more resistant than men to the development of vascular diseases. However, menopause is a factor leading to deterioration of female vascular integrity, and it is reported that the risk of vascular diseases such as atherosclerosis and abdominal aortic aneurysm is increased in postmenopausal women. Although it is suggested that perivascular adipose tissue (PVAT) is deeply involved in the increased risk of vascular disease development, the effect of menopause on PVAT integrity is unknown. In this study, we aimed to elucidate the effect of menopause on PVAT in ovariectomized (OVX) rats. PVAT was divided into 4 regions based on characteristics. Hypertrophy and increased inflammation of adipocytes in the PVAT were observed in the OVX group, but the effects of OVX were different for each region. OVX induced matrix metalloproteinase (MMP) -9 which degrade extracellular matrix such as elastin and collagen fibers in PVAT. Degeneration of the arterial fibers of the thoracic and abdominal aorta were observed in the OVX group. These results indicate that OVX can cause dysfunction of PVAT which can cause degradation of arterial fibers. Appropriate management of PVAT may play an important role in the prevention and treatment of diseases originating from ovarian hypofunction.

Topics: Adipocytes; Adipose Tissue; Animals; Aorta; Aortic Aneurysm, Abdominal; Arteries; Atherosclerosis; Collagen; Elastin; Extracellular Matrix; Female; Matrix Metalloproteinase 9; Menopause; Ovariectomy; Ovary; Rats, Sprague-Dawley

Elastase-induced abdominal aortic aneurysm (AAA) model is widely used for aneurysmal pathogenesis and translational research. However, temporal alternations in aneurysmal histologies remain unknown. This study is aimed at analyzing temporal immunopathologies of aneurysmal aorta following experimental AAA induction.. Male C57BL/6J mice at the age of 10-14 weeks received intra-aortic infusion of elastase to induce AAAs. Aortic diameters at the baseline and indicated days after AAA induction were measured, and aortae were collected for histopathological analysis.. Aorta diameters increased from 0.52 mm at the baseline levels to 0.99 mm, 1.34 mm, and 1.41 mm at days 7, 14, and 28, respectively, corresponding 90%, 158%, and 171% increases over the baseline level. Average aortic diameters did not differ between days 14 and 28. Severe elastin degradation and smooth muscle cell depletion were found at days 14 and 28 as compared to the baseline and day 7. No difference in the scores of medial elastin and SMC destruction was noted between days 14 and 28. Consistent results were found for leukocyte accumulation, neoangiogenesis, and matrix metalloproteinase expression. Twenty-eight days after AAA induction, all aneurysmal pathologies showed an attenuated trend, although most histopathological parameters did no differ between days 14 and 28.. Our data suggest that almost aneurysmal immunohistopathologies reach maximal 14 days following AAA induction. Analysis of day 14 histologies is sufficient for AAA pathogenesis and translational studies in elastase-induced mouse experimental AAAs.

Topics: Animals; Aorta; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elastin; Humans; Infusions, Intra-Arterial; Male; Matrix Metalloproteinases; Mice; Mice, Inbred C57BL; Myocytes, Smooth Muscle; Neovascularization, Pathologic; Pancreatic Elastase

Abdominal aortic aneurysm (AAA) disease causes dilation of the aorta, leading to aortic rupture and death if not treated early. It is the 14th leading cause of death in the U.S. and 10th leading cause of death in men over age 55, affecting thousands of patients. Despite the prevalence of AAA, no safe and efficient pharmacotherapies exist for patients. The deterioration of the elastic lamina in the aneurysmal wall is a consistent feature of AAAs, making it an ideal target for delivering drugs to the AAA site. In this research, we conjugated nanoparticles with an elastin antibody that only targets degraded elastin while sparing healthy elastin. After induction of aneurysm by 4-week infusion of angiotensin II (Ang II), two biweekly intravenous injections of pentagalloyl glucose (PGG)-loaded nanoparticles conjugated with elastin antibody delivered the drug to the aneurysm site. We show that targeted delivery of PGG could reverse the aortic dilation, ameliorate the inflammation, restore the elastic lamina, and improve the mechanical properties of the aorta at the AAA site. Therefore, simple iv therapy of PGG loaded nanoparticles can be an effective treatment option for early to middle stage aneurysms to reverse disease progression and return the aorta to normal homeostasis.

Topics: Angiotensin II; Animals; Antibodies; Aortic Aneurysm, Abdominal; Drug Delivery Systems; Elastin; Hydrolyzable Tannins; Injections, Intravenous; Male; Mice; Mice, Inbred C57BL; Nanoparticles; Serum Albumin, Bovine

Background Abdominal aortic aneurysm (AAA) is a life-threatening vascular disorder characterized by chronic inflammation of the aortic wall, which lacks effective pharmacotherapeutic remedies and has an extremely high mortality. Nuclear receptor NR4A1 (Nur77) functions in various chronic inflammatory diseases. However, the influence of Nur77 on AAA has remained unclear. Herein, we sought to determine the effects of Nur77 on the development of AAA. Methods and Results We observed that Nur77 expression decreased significantly in human and mice AAA lesions. Deletion of Nur77 accelerated the development of AAA in mice, as evidenced by increased AAA incidence, abdominal aortic diameters, elastin fragmentation, and collagen content. Consistent with genetic manipulation, pharmacological activation of Nur77 by celastrol showed beneficial effects against AAA. Microscopic and molecular analyses indicated that the detrimental effects of Nur77 deficiency were associated with aggravated macrophage infiltration in AAA lesions and increased pro-inflammatory cytokines secretion and matrix metalloproteinase (MMP-9) expression. Bioinformatics analyses further revealed that LOX-1 was upregulated by Nur77 deficiency and consequently increased the expression of cytokines and MMP-9. Moreover, rescue experiments verified that LOX-1 notably aggravated inflammatory response, an effect that was blunted by Nur77. Conclusions This study firstly demonstrated a crucial role of Nur77 in the formation of AAA by targeting LOX-1, which implicated Nur77 might be a potential therapeutic target for AAA.

Topics: Animals; Aorta; Aortic Aneurysm, Abdominal; Cytokines; Drug Discovery; Elastin; Humans; Inflammation; Matrix Metalloproteinase 9; Mice; Mice, Knockout; Nuclear Receptor Subfamily 4, Group A, Member 1; Organ Size; Scavenger Receptors, Class E; Signal Transduction; Vascular Remodeling

Abdominal aortic aneurysms (AAAs) are characterized histopathologically by compromised elastic fiber integrity, lost smooth muscle cells or their function, and remodeled collagen. We used a recently introduced mouse model of AAAs that combines enzymatic degradation of elastic fibers and blocking of lysyl oxidase, and thus matrix cross-linking, to study progressive dilatation of the infrarenal abdominal aorta, including development of intraluminal thrombus. We quantified changes in biomaterial properties and biomechanical functionality within the aneurysmal segment as a function of time of enlargement and degree of thrombosis. Towards this end, we combined multi-modality imaging with state-of-the art biomechanical testing and histology to quantify regional heterogeneities for the first time and we used a computational model of arterial growth and remodeling to test multiple hypotheses, suggested by the data, regarding the degree of lost elastin, accumulation of glycosaminoglycans, and rates of collagen turnover. We found that standard histopathological findings can be misleading, while combining advanced experimental and computational methods revealed that glycosaminoglycan accumulation is pathologic, not adaptive, and that heightened collagen deposition is ineffective if not cross-linked. In conclusion, loss of elastic fiber integrity can be a strong initiator of aortic aneurysms, but it is the rate and effectiveness of fibrillar collagen remodeling that dictates enlargement. STATEMENT OF SIGNIFICANCE: Precise mechanisms by which abdominal aortic aneurysms enlarge remain unclear, but a recent elastase plus β-aminopropionitrile mouse model provides new insight into disease progression. As in the human condition, the aortic degeneration and adverse remodeling are highly heterogeneous in this model. Our multi-modality experiments quantify and contrast the heterogeneities in geometry and biomaterial properties, and our computational modeling shows that standard histopathology can be misleading. Neither accumulating glycosaminoglycans nor frustrated collagen synthesis slow disease progression, thus highlighting the importance of stimulating adaptive collagen remodeling to limit lesion enlargement.

Topics: Aminopropionitrile; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elastic Tissue; Elastin; Mice; Pancreatic Elastase

Overactivated B cells secrete pathological antibodies, which in turn accelerate the formation of abdominal aortic aneurysms (AAAs). Hyperhomocysteinaemia (HHcy) aggravates AAA in mice; however, the underlying mechanisms remain largely elusive. In this study, we further investigated whether homocysteine (Hcy)-activated B cells produce antigen-specific antibodies that ultimately contribute to AAA formation.. ELISA assays showed that HHcy induced the secretion of anti-beta 2 glycoprotein I (anti-β2GPI) antibody from B cells both in vitro and in vivo. Mechanistically, Hcy increased the accumulation of various lipid metabolites in B cells tested by liquid chromatography-tandem mass spectrometry, which contributed to elevated anti-β2GPI IgG secretion. By using the toll-like receptor 4 (TLR4)-specific inhibitor TAK-242 or TLR4-deficient macrophages, we found that culture supernatants from Hcy-activated B cells and HHcy plasma IgG polarized inflammatory macrophages in a TLR4-dependent manner. In addition, HHcy markedly increased the incidence of elastase- and CaPO4-induced AAA in male BALB/c mice, which was prevented in μMT mice. To further determine the importance of IgG in HHcy-aggravated AAA formation, we purified plasma IgG from HHcy or control mice and then transferred the IgG into μMT mice, which were subsequently subjected to elastase- or CaPO4-induced AAA. Compared with μMT mice that received plasma IgG from control mice, μMT mice that received HHcy plasma IgG developed significantly exacerbated elastase- or CaPO4-induced AAA accompanied by increased elastin degradation, MMP2/9 expression, and anti-β2GPI IgG deposition in vascular lesions, as shown by immunofluorescence histochemical staining.. Our findings reveal a novel mechanism by which Hcy-induced B cell-derived pathogenic anti-β2GPI IgG might, at least in part, contribute to HHcy-aggravated chronic vascular inflammation and AAA formation.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Autoantibodies; B-Lymphocytes; beta 2-Glycoprotein I; Calcium Phosphates; Cells, Cultured; Disease Models, Animal; Elastin; Hyperhomocysteinemia; Macrophages; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Knockout; Pancreatic Elastase; Toll-Like Receptor 4

Aortic mural inflammatory damage takes a vital part in abdominal aortic aneurysm (AAA). Recently, ulinastatin (UTI) has attracted attention for its anti-inflammatory function. Our study aimed to evaluate potential influences of UTI on experimental AAA.. A mouse model of AAA was induced by infusion of porcine pancreatic elastase (PPE) into the abdominal aorta. Mice were treated with UTI (50,000 U/kg/day i.p.) beginning either immediately or on the 4th day after PPE infusion, with treatment being continued until the 14th day. UTI effects were assessed by aortic diameter measurements and aortic histopathological analysis.. Significant and time-dependent aortic diameter enlargement persisted in the control mice from day 0. In the UTI group, aortic diameter increased, and depletion of aortic mural smooth muscle cells and elastin was significantly -attenuated. Simultaneously, mural CD68+ macrophages, CD8+ T-cell and B220+ B-cell density, as well as neoangiogenesis were suppressed by UTI. In addition, delayed UTI treatment could still effectively limit aneurysm expansion.. UTI treatment limits the formation and growth of experimental AAA, and UTI may be a potential treatment for early AAA disease.

Topics: Animals; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elastin; Glycoproteins; Male; Mice; Mice, Inbred C57BL; Myocytes, Smooth Muscle; Neovascularization, Physiologic; Toll-Like Receptor 4

The aim of the study was to determine whether magnetic resonance imaging (MRI) can be used in assessment of biologic activity of intraluminal thrombus (ILT) and proteolytic processes of the abdominal aortic aneurysm wall.. Using MRI, 50 patients with asymptomatic infrarenal abdominal aortic aneurysm were analyzed at the maximum aneurysm diameter on T1-weighted images in the arterial phase after administration of contrast material. Relative ILT signal intensity (SI) was determined as the ratio between ILT SI and psoas muscle SI. During surgery, the full thickness of the ILT and the adjacent part of the aneurysm wall were harvested at the maximal diameter for biochemical analysis. The concentrations of matrix metalloproteinase 9 and neutrophil elastase (NE/ELA) were analyzed in harvested thrombi, and the concentrations of collagen type III, elastin, and proteoglycans were analyzed in harvested aneurysm walls.. A significant positive correlation was found between the NE/ELA concentration of the ILT and the relative SI (ρ = 0.309; P = .029). Furthermore, a negative correlation was observed between the elastin content of the aneurysm wall and the relative SI (ρ = -0.300; P = .034). No correlations were found between relative SI and concentration of matrix metalloproteinase 9, NE/ELA, collagen type III, or proteoglycan 4 in the aneurysm wall.. These findings indicate a potential novel use of MRI in prediction of thrombus proteolytic enzyme concentrations and the extracellular matrix content of the aneurysm wall, thus providing additional information for the risk of potential aneurysm rupture.

Topics: Aged; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Collagen Type III; Cross-Sectional Studies; Elastin; Female; Humans; Leukocyte Elastase; Magnetic Resonance Imaging; Male; Matrix Metalloproteinase 9; Middle Aged; Predictive Value of Tests; Proteoglycans; Proteolysis; Thrombosis

Abdominal aortic aneurysms (AAA) is a life-threatening weakening and expansion of the abdominal aorta due to inflammatory cell infiltration and gradual degeneration of extracellular matrix (ECM). There are no pharmacological therapies to treat AAA. We tested the hypothesis that nanoparticle (NP) therapy that targets degraded elastin and delivers anti-inflammatory, anti-oxidative, and ECM stabilizing agent, pentagalloyl glucose (PGG) will reverse advance stage aneurysm in an elastase-induced mouse model of AAA.. Porcine pancreatic elastase (PPE) was applied periadventitially to the infrarenal aorta in mice and AAA was allowed to develop for 14 days. Nanoparticles loaded with PGG (EL-PGG-NPs) were then delivered via IV route at 14-day and 21-day (10 mg/kg of body weight). A control group of mice received no therapy. The targeting of NPs to the AAA site was confirmed with fluorescent dye marked NPs and gold NPs. Animals were sacrificed at 28-d. We found that targeted PGG therapy reversed the AAA by decreasing matrix metalloproteinases MMP-9 and MMP-2, and the infiltration of macrophages in the medial layer. The increase in diameter of the aorta was reversed to healthy controls. Moreover, PGG treatment restored degraded elastic lamina and increased the circumferential strain of aneurysmal aorta to the healthy levels.. Our results support that site-specific delivery of PGG with targeted nanoparticles can be used to treat already developed AAA. Such therapy can reverse inflammatory markers and restore arterial homeostasis.

Topics: Animals; Antibodies; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Disease Models, Animal; Drug Carriers; Elastin; Extracellular Matrix; Gold; Humans; Hydrolyzable Tannins; Immunoconjugates; Injections, Intravenous; Male; Metal Nanoparticles; Mice; Pancreatic Elastase; Serum Albumin, Bovine; Ultrasonography

Using maximum diameter of an abdominal aortic aneurysm (AAA) alone for management can lead to delayed interventions or unnecessary urgent repairs. Abdominal aortic aneurysm stiffness plays an important role in its expansion and rupture. In vivo aortic magnetic resonance elastography (MRE) was developed to spatially measure AAA stiffness in previous pilot studies and has not been thoroughly validated and evaluated for its potential clinical value. This study aims to evaluate noninvasive in vivo aortic MRE-derived stiffness in an AAA porcine model and investigate the relationships between MRE-derived AAA stiffness and (1) histopathology, (2) uniaxial tensile test, and (3) burst testing for assessing MRE's potential in evaluating AAA rupture risk.. Abdominal aortic aneurysm was induced in 31 Yorkshire pigs (n = 226 stiffness measurements). Animals were randomly divided into 3 cohorts: 2-week, 4-week, and 4-week-burst. Aortic MRE was sequentially performed. Histopathologic analyses were performed to quantify elastin, collagen, and mineral densities. Uniaxial tensile test and burst testing were conducted to measure peak stress and burst pressure for assessing the ultimate wall strength.. Magnetic resonance elastography-derived AAA stiffness was significantly higher than the normal aorta. Significant reduction in elastin and collagen densities as well as increased mineralization was observed in AAAs. Uniaxial tensile test and burst testing revealed reduced ultimate wall strength. Magnetic resonance elastography-derived aortic stiffness correlated to elastin density (ρ = -0.68; P < 0.0001; n = 60) and mineralization (ρ = 0.59; P < 0.0001; n = 60). Inverse correlations were observed between aortic stiffness and peak stress (ρ = -0.32; P = 0.0495; n = 38) as well as burst pressure (ρ = -0.55; P = 0.0116; n = 20).. Noninvasive in vivo aortic MRE successfully detected aortic wall stiffening, confirming the extracellular matrix remodeling observed in the histopathologic analyses. These mural changes diminished wall strength. Inverse correlation between MRE-derived aortic stiffness and aortic wall strength suggests that MRE-derived stiffness can be a potential biomarker for clinically assessing AAA wall status and rupture potential.

Topics: Animals; Aortic Aneurysm, Abdominal; Collagen; Disease Models, Animal; Elasticity Imaging Techniques; Elastin; Swine; Vascular Calcification; Vascular Stiffness

Surgical intervention is currently the only option for an abdominal aortic aneurysm (AAA), preventing its rupture and sudden death of a patient. Therefore, it is crucial to determine the pathogenic mechanisms of this disease for the development of effective pharmacological therapies. Oxidative stress is said to be one of the pivotal factors in the pathogenesis of AAAs. Thus, we aimed to evaluate the significance of nuclear factor erythroid 2-related factor 2 (Nrf2) transcriptional activity in the development of AAA and to verify if simvastatin, administered as pre- and cotreatment, may counteract this structural malformation. Experiments were performed on mice with inhibited transcriptional activity of Nrf2 (tKO) and wild-type (WT) counterparts. We used a model of angiotensin II- (AngII-) induced AAA, combined with a fat-enriched diet. Mice were administered with AngII or saline for up to 28 days

Topics: Angiotensin II; Animals; Aorta; Aortic Aneurysm, Abdominal; Blood Pressure; Collagen; Elastin; Humans; Inflammation; Mice, Inbred C57BL; Mice, Knockout; NF-E2-Related Factor 2; Oxidative Stress; Reactive Oxygen Species; Receptor, Angiotensin, Type 1; Signal Transduction; Simvastatin; Transcription, Genetic; Vascular Cell Adhesion Molecule-1

Abdominal aortic aneurysm (AAA), commonly occurring in the aged population, is a degenerative disease that dilate and weaken infrarenal aorta due to progressive degeneration of aortic wall integrity. Vinpocetine, a derivative of alkaloid vincamine, has long been used for cerebrovascular disorders and cognitive impairment in the aged population. Recent studies have indicated that vinpocetine antagonizes occlusive vascular disorders such as intimal hyperplasia and atherosclerosis. However, its role in vascular degenerative disease AAA remains unexplored. Herein, we determined the effect of vinpocetine on the formation of AAA as well as the intervention of pre-existing moderate AAA. AAA was induced by periaortic elastase application in C57BL/6J mice. Systemic vinpocetine treatment was applied daily via intraperitoneal injection. We showed that vinpocetine pre-treatment remarkably attenuated aneurysmal dilation assessed by diameter and volume. More importantly, vinpocetine also significantly suppressed the progression of pre-existing moderate AAA in a post-intervention model. Vinpocetine improved multiple cellular and molecular changes associated with AAA, such as elastin degradation, media smooth muscle cell depletion, collagen fibers remodeling and macrophage infiltration in aneurysmal tissues. Vinpocetine potently suppressed tumor necrosis factor-α-induced nuclear factor kappa-light-chain-enhancer of activated B cells activation and proinflammatory mediator expression in primary cultured macrophages in vitro, as well as in the aorta wall in vivo, suggesting vinpocetine conferred anti-AAA effect at least partially via the inhibition of inflammation. Taken together, our findings reveal a novel role of vinpocetine in AAA formation, development and progression. Given the excellent safety profile of vinpocetine, the present study suggests vinpocetine may be a novel therapeutic agent for AAA prevention and treatment.

Topics: Animals; Aortic Aneurysm, Abdominal; Cells, Cultured; Dilatation, Pathologic; Disease Progression; Elastin; Inflammation; Macrophages; Mice, Inbred C57BL; Myocytes, Smooth Muscle; NF-kappa B; Protective Agents; Proteoglycans; Proteolysis; Vinca Alkaloids

Abdominal aortic aneurysm (AAA) is a vascular disease characterized by the weakening of the vascular walls and the progressive dilation of the abdominal aorta. Nicotine, a primary component of cigarette smoke, is associated with AAA development and rupture. Nicotine induces AAA development by weakening vascular walls. However, little is known about preventive methods using functional food factors for nicotine-induced vascular destruction. Sesamin and sesamolin are functional food factors that are fat-soluble lignans found in Sesamum indicum seeds. Previous reports indicated that sesamin and sesamolin have anti-oxidative and anti-inflammatory effects. In this study, we evaluated the effects of sesamin and sesamolin-rich sesame extract on the weakening of vascular walls in nicotine-administered mice. Sesame extract attenuated the degradation of collagen and elastin fibers caused by nicotine. In addition, sesame extract decreased the area positive for matrix metalloproteinase 12 (MMP-12) and oxidative stress in the vascular walls. These results suggest that sesame extract may decrease the weakening of vascular walls by suppressing the nicotine-induced degradation of collagen and elastin fibers. Sesame extract may be effective in preventing AAA development by decreasing both, MMP-12 expression and oxidative stress in vascular walls.

Topics: Animals; Aorta, Thoracic; Aortic Aneurysm, Abdominal; Body Weight; Collagen; Dioxoles; Eating; Elastin; Lignans; Male; Matrix Metalloproteinase 12; Mice, Inbred C57BL; Nicotine; Oxidative Stress; Plant Extracts; Sesamum

Molecular magnetic resonance imaging is a promising modality for the characterization of abdominal aortic aneurysms (AAAs). The combination of different molecular imaging biomarkers may improve the assessment of the risk of rupture. This study investigates the feasibility of imaging inflammatory activity and extracellular matrix degradation by concurrent dual-probe molecular magnetic resonance imaging in an AAA mouse model.. Osmotic minipumps with a continuous infusion of Ang II (angiotensin II; 1000 ng/[kg·min]) to induce AAAs were implanted in apolipoprotein-deficient mice (N=58). Animals were assigned to 2 groups. In group 1 (longitudinal group, n=13), imaging was performed once after 1 week with a clinical dose of a macrophage-specific iron oxide-based probe (ferumoxytol, 4 mgFe/kg, surrogate marker for inflammatory activity) and an elastin-specific gadolinium-based probe (0.2 mmol/kg, surrogate marker for extracellular matrix degradation). Animals were then monitored with death as end point. In group 2 (week-by-week-group), imaging with both probes was performed after 1, 2, 3, and 4 weeks (n=9 per group). Both probes were evaluated in 1 magnetic resonance session.. The combined assessment of inflammatory activity and extracellular matrix degradation was the strongest predictor of AAA rupture (sensitivity 100%; specificity 89%; area under the curve, 0.99). Information from each single probe alone resulted in lower predictive accuracy. In vivo measurements for the elastin- and iron oxide-probe were in good agreement with ex vivo histopathology (Prussian blue-stain: R. This study demonstrates the potential of the concurrent assessment of inflammatory activity and extracellular matrix degradation by dual-probe molecular magnetic resonance imaging in an AAA mouse model. Based on the combined information from both molecular probes, the rupture of AAAs could reliably be predicted.

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Rupture; Contrast Media; Disease Models, Animal; Disease Progression; Elastin; Extracellular Matrix; Feasibility Studies; Ferrosoferric Oxide; Gadolinium DTPA; Inflammation Mediators; Magnetic Resonance Imaging; Male; Mice, Knockout, ApoE; Molecular Imaging; Predictive Value of Tests; Reproducibility of Results; Time Factors

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apoptosis; Cell Line; Disease Models, Animal; Elastin; Male; MAP Kinase Signaling System; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice; Mice, Knockout, ApoE; Myocytes, Smooth Muscle; Neuropeptides; Proteolysis; Reactive Oxygen Species

Abdominal aortic aneurysm (AAA) has high mortality rate when ruptured, but currently, there is no proven pharmacological therapy for AAA because of our poor understanding of its pathogenesis. The current study explored a novel role of smooth muscle cell (SMC) BMAL1 (brain and muscle Arnt-like protein-1)-a transcription factor known to regulate circadian rhythm-in AAA development.. SMC-selective deletion of BMAL1 potently protected mice from AAA induced by (1) MR (mineralocorticoid receptor) agonist deoxycorticosterone acetate or aldosterone plus high salt intake and (2) angiotensin II infusion in hypercholesterolemia mice. Aortic BMAL1 was upregulated by deoxycorticosterone acetate-salt, and deletion of BMAL1 in SMCs selectively upregulated TIMP4 (tissue inhibitor of metalloproteinase 4) and suppressed deoxycorticosterone acetate-salt-induced MMP (matrix metalloproteinase) activation and elastin breakages. Moreover, BMAL1 bound to the. These results reveal an important, but previously unexplored, role of SMC BMAL1 in AAA. Moreover, these results identify TIMP4 as a novel target of BMAL1, which may mediate the AAA protective effect of SMC BMAL1 deletion.

Topics: Aldosterone; Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; ARNTL Transcription Factors; Binding Sites; Desoxycorticosterone Acetate; Dilatation, Pathologic; Disease Models, Animal; Elastin; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice, Inbred C57BL; Mice, Knockout; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Promoter Regions, Genetic; Sodium Chloride, Dietary; Tissue Inhibitor of Metalloproteinase-4; Tissue Inhibitor of Metalloproteinases; Transcription, Genetic

Abdominal aortic aneurysms (AAA) is a chronic inflammatory disease in which signal transducer and activator of transcription 3 (STAT3), and disintegrin and metalloproteinase 17 (ADAM17) play important roles. However, it remains unclear whether ursolic acid (UA), a natural pentacyclic triterpenoid carboxylic acid, can have an impact on STAT3 and ADAM17 and hence influence the formation of AAA. The objective of this study was to characterize the potential effect of UA on the pathogenesis of AAA and on STAT3 and ADAM17.. UA decreased the incidence of AngII-induced AAA in mice. UA alleviated the degradation of elastin fibers and inflammation and decreased the expression of MMP2, MMP9, ADAM17 and phospho-STAT3 (pSTAT3) in aorta of mice induced with AngII. UA inhibited the constitutive and stimuli-induced (AngII and tumor necrosis factor-α) expression of MMP2, MMP9, ADAM17 and pSTAT3 in vascular smooth muscle cells (VSMCs). Furthermore, UA decreased cell viability, and suppressed colony formation and wound healing in vitro.. We demonstrated that UA ameliorated the severity of AAA and exhibited an inhibitory effect on the expression of pSTAT3 and ADAM17. UA might emerge as a promising agent contributing to the prevention or treatment of AAA.

Topics: ADAM17 Protein; Angiotensin II; Animals; Anti-Inflammatory Agents; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Cell Line; Cell Proliferation; Disease Models, Animal; Elastin; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice, Knockout, ApoE; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Phosphorylation; Signal Transduction; STAT3 Transcription Factor; Triterpenes; Ursolic Acid; Vascular Remodeling; Wound Healing

Abdominal aortic aneurysm (AAA) is a vascular disease that results in rupture of the abdominal aorta. The risk factors for the development of AAA include smoking, male sex, hypertension, and age. AAA has a high mortality rate, but therapy for AAA is restricted to surgery in cases of large aneurysms. Clarifying the effect of dietary food on the development of AAA would be helpful for patients with AAAs. However, the relationship between dietary habits and the development of AAA is largely unknown. In our previous study, we demonstrated that adipocytes in vascular wall can induce the rupture of AAA. Therefore, we focused on the diet-induced abnormal triglyceride metabolism, which has the potential to drive AAA development. In this study, we have evaluated the effects of a high-sucrose diet on the development of AAA in a vascular hypoperfusion-induced animal model. A high sucrose diet induced high serum TG level and fatty liver. However, the AAA rupture risk and the AAA diameter were not significantly different between the control and high-sucrose groups. The intergroup differences in the elastin degradation score and collagen-positive area were insignificant. Moreover, matrix metalloproteinases, macrophages, and monocyte chemoattractant protein-1-positive areas did not differ significantly between groups. These results suggest that a high-sucrose diet does not affect the appearance of vascular adipocyte and AAA development under the vascular hypoperfusion condition.

Topics: Adipocytes; Aneurysm, Ruptured; Animals; Aortic Aneurysm, Abdominal; Collagen; Diet, Carbohydrate Loading; Dietary Sucrose; Disease Models, Animal; Elastin; Fatty Liver; Male; Rats, Sprague-Dawley; Risk Factors; Triglycerides

Abdominal aortic aneurysm (AAA) is the pathological dilation and weakening of the abdominal aorta wall. Inflammation, degradation of the extracellular matrix (ECM) and loss of smooth muscle cells and skewing of their function are pivotal in AAA pathology. We developed a recombinant collagen-based patch (RCP) to provide structural integrity and deliver Adipose tissue-Derived Stromal Cells (ASC) for repair. Patches supported adhesion and function as well as proliferation of ASC. ASC-loaded RCPs or bare patches, applied around the aorta after AAA induction in rats, both maintained structural integrity of the aortic wall at time of explant (2w). However, wall thinning, accompanied by loss of elastin fibers and loss of medial SMC, was only attenuated in ASC-loaded RCP-treated AAA rats. Interestingly, this coincided with migration of ASC into the media and a reduced influx of macrophages. We hypothesize that the medially-migrated ASC dampened or skewed the adverse innate immunity and thus suppressed SMC apoptosis, phenotypic skewing and elastin degradation. We conclude that the periadventitial delivery of ASC with RCP suppresses development and progression of AAA, which is has an expected future clinical benefit in combination with an appropriate early screening program of patients at risk for aneurysms. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A:2494-2506, 2018.

Topics: Adipose Tissue; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Blood Vessels; Cell Adhesion; Cell Death; Cell Movement; Culture Media, Conditioned; Dilatation; Elastin; Humans; Macrophages; Male; Myocytes, Smooth Muscle; Proteolysis; Rats, Inbred F344; Recombinant Proteins; Stromal Cells; Surface Properties; Tissue Scaffolds; Wound Healing

The pathogenesis driving the formation of abdominal aortic aneurysms continues to be poorly understood. Therefore, we systemically define the cytokine and circulating immune cell environment observed in human abdominal aortic aneurysm compared with risk-factor matched controls.. From 2015 to 2017, a total of 274 patients donated blood to the Indiana University Center for Aortic Disease. Absolute concentrations of circulating cytokines were determined, using enzyme-linked immunosorbent assays while the expression of circulating immune cell phenotypes were assayed via flow cytometric analysis.. Human abdominal aortic aneurysm is characterized by a significant depletion of the antigen-specific, CD4. In this investigation, we systematically characterize the abdominal aortic aneurysm-immune environment and present preliminary evidence that faulty immune regulation may also contribute to aneurysm formation and growth.

Topics: Aged; Aortic Aneurysm, Abdominal; Case-Control Studies; CD4-Positive T-Lymphocytes; Collagen Type V; Cytokines; Elastin; Female; Humans; Macrophages; Male; Middle Aged; Risk Factors

Particulate matter 2.5 (PM2.5) has proven to be associated with morbidity and mortality from cardiovascular diseases. However, whether PM2.5 could promote the formation of abdominal aortic aneurysm (AAA) is unclear. Present study aimed to explore the relationship between PM2.5 exposure and AAA development.. Ang Ⅱ-infused apoe. We found that PM2.5 could significantly increase the AAA incidence, the maximal abdominal aortic diameter and could promote the degradation of elastin. Additionally, the expression of senescence markers, P21 and P16 were also enhanced after PM2.5 exposure. We also found that PM2.5 significantly increased the AAA related pathological changes, MMP2 and MCP-1 expression in HASMCs. Meanwhile, PM2.5 could increase the expression of senescence markers P21, P16 and SA-β-gal activity, also the reactive oxygen species levels in vitro.. PM2.5 promoted the formation of AAA in an Ang Ⅱ-induced AAA model. The underlying mechanism might be cellular senescence after PM2.5 exposure.

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; beta-Galactosidase; Biomarkers; Cell Line; Chemokine CCL2; Cyclin-Dependent Kinase Inhibitor p16; Cyclin-Dependent Kinase Inhibitor p21; Disease Models, Animal; Elastin; Humans; Matrix Metalloproteinase 2; Mice; Mice, Inbred C57BL; Myocytes, Smooth Muscle; Particulate Matter; Reactive Oxygen Species

The self-healing phenomenon can be found in the elastase-induced abdominal aortic aneurysm (AAA) model, and an enlarging AAA model was successfully induced by coarctation. Unfortunately, aortic coarctation in these enlarging models is generally not found in human AAA disease. This study aimed to create an experiment model of enlarging AAA in rabbits to better mimic human aortic aneurysm disease. Eighty-four male New Zealand white rabbits were randomly divided into three equal groups: two aneurysm groups (A and B) and a SHAM group. Aneurysm group rabbits underwent extrinsic aortic stenosis below the right renal artery and received a 10-minute incubation of 60 μl elastase (1 unit/μl). Absorbable suture was used in Group A and nonabsorbable cotton thread was used in Group B. A sham operation was performed in the SHAM group. Aortic diameter was measured after 1, 3, 7, and 15 weeks; thereafter animals were sacrificed for histopathological, immunohistochemical and quantitative studies. Two rabbits died at 29 and 48 days, respectively, after operation in Group B. All aneurysms formed and enlarged progressively by 3 weeks in the Aneurysm groups. However, diameter enlargement in Group A was significantly lower than that in Group B at 7 weeks. Aneurysm groups developed intimal hyperplasia; intima-media thickness (IMT) increased significantly by week 7, and aortic media thickness and intima-media ratio (IMR) increased significantly by week 15. Marked destruction of elastin fibers and smooth muscle cells (SMCs) occurred 1 week later and increased progressively thereafter. Intimal hyperplasia and SMCs content in Group A increased significantly by week 15 compared with Group B. Aneurysm groups exhibited strong expression of matrix metalloproteinases 2 and 9 and RAM11 by week 1, and decreased progressively thereafter. In conclusion, this novel rabbit AAA model enlarges progressively without coarctation and is capable of better mimicking human aortic aneurysm disease.

Topics: Angiography, Digital Subtraction; Animals; Aortic Aneurysm, Abdominal; Carotid Intima-Media Thickness; Disease Models, Animal; Elastic Tissue; Elastin; Humans; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Myocytes, Smooth Muscle; Pancreatic Elastase; Rabbits; Time Factors

Tamsulosin, an α. Abdominal aortic aneurysms were induced in WT C57BL/6 male mice (n = 9-18/group), using an established topical elastase abdominal aortic aneurysm model. Osmotic pumps were implanted in mice 5 days before operation to create the model, administering either low dose (0.125 µg/day tamsulosin), high dose (0.250µg/day tamsulosin), or vehicle treatments with and without topical application of elastase. Blood pressures were measured preoperatively and on postoperative days 0, 3, 7, and 14. On postoperative day 14, aortic diameter was measured before harvest. Sample aortas were prepared for histology and cytokine analysis.. Measurements of systolic blood pressure did not differ between groups. Mice treated with the low dose of tamsulosin and with the high dose of tamsulosin showed decreased aortic diameter compared with vehicle-treated control (93% ± 24 versus 94% ± 30 versus 132% ± 24, respectively; P = .0003, P = .0003). Cytokine analysis demonstrated downregulation of pro-inflammatory cytokines in both treatment groups compared with the control (P < .05). Histology exhibited preservation of elastin in both low- and high-dose tamsulosin-treated groups (P = .0041 and P = .0018, respectively).. Tamsulosin attenuates abdominal aortic aneurysm formation with increased preservation of elastin and decreased production of pro-inflammatory cytokines. Further studies are necessary to elucidate the mechanism by which tamsulosin attenuates abdominal aortic aneurysm pathogenesis.

Topics: Adrenergic alpha-1 Receptor Antagonists; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Blood Pressure; Cytokines; Disease Models, Animal; Down-Regulation; Drug Evaluation, Preclinical; Elastin; Humans; Male; Mice; Mice, Inbred C57BL; Pancreatic Elastase; Tamsulosin; Treatment Outcome

Abdominal aortic aneurysm (AAA) is a vascular disease characterized by chronic inflammation in the infrarenal aorta. Epidemiologic data have clearly linked tobacco smoking to aneurysm formation and a faster rate of expansion. It suggested that nicotine, one of the main ingredients of tobacco, has been suggested to be associated with AAA development and rupture. In the condition where no established drugs are available; therefore, an effective approach to prevent the vascular damage from nicotine consumption may be the use of dietary functional food factors. However, little is known about the relationship between dietary components and AAA. In this study, we estimated the effect of dietary deoxyribonucleic acid (DNA) on the vascular wall. After habituation for 5 d, the mice were divided into four groups: control diet and distilled water group (C), DNA-Na diet and distilled water group (DNA), control diet and 0.5 mg/mL nicotine solution group (C-Nic), DNA-Na diet, and 0.5 mg/mL nicotine solution group (DNA-Nic). The dietary DNA attenuated the degradation of elastin fibers induced by nicotine administration. The areas stained positive for MMP-2 in the DNA-Nic group were significantly suppressed compared to C-Nic mice. These data suggest that the dietary DNA may prevent the weakening of the aortic wall via inhibition of the MMP-2-dependent pathway. In conclusion, we have revealed the protective effect of dietary DNA on the vascular pathology of nicotine-administrated mice. A nucleic acid-rich diet might be useful for people who consume nicotine via smoking, chewing tobacco, or nicotine patches.

Topics: Adventitia; Animals; Anti-Inflammatory Agents, Non-Steroidal; Antioxidants; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Cardiovascular Agents; Dietary Supplements; Disease Models, Animal; DNA; Elastin; Endothelium, Vascular; Immunohistochemistry; Male; Matrix Metalloproteinase 2; Mice, Inbred C57BL; Nicotine; Oxidative Stress; Proteolysis

Abdominal aortic aneurysm (AAA) is a common age-related vascular disease characterized by progressive weakening and dilatation of the aortic wall. Thrombospondin-1 (TSP-1; gene Thbs1) is a member of the matricellular protein family important in the control of extracellular matrix (ECM) remodelling. In the present study, the association of serum TSP-1 concentration with AAA progression was assessed in 276 men that underwent repeated ultrasound for a median 5.5 years. AAA growth was negatively correlated with serum TSP-1 concentration (

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; Biomarkers; Cells, Cultured; Collagen Type III; Disease Models, Animal; Disease Progression; Elastin; Genetic Predisposition to Disease; Humans; Low Density Lipoprotein Receptor-Related Protein-1; Male; Matrix Metalloproteinase 9; Mice, Knockout; Odds Ratio; Phenotype; Proteolysis; Receptors, LDL; Risk Factors; Thrombospondin 1; Time Factors; Tumor Suppressor Proteins; Ultrasonography; Vascular Remodeling

A primary deficiency in predicting the progression and rupture-risk of abdominal aortic aneurysms (AAAs) is an inability to assign patient-specific, heterogeneous biomechanical properties to the remodelling aortic wall. Toward this end, we investigated possible correlations between three quantities having the potential for non-invasive measurement (diameter, wall thickness, and strain) and local wall microstructure within evolving experimental AAAs. AAAs were initiated in male C57BL/6J mice via in situ adventitial application of elastase and allowed to progress for 1-4 weeks. Regional in vitro Green strain was assessed using custom panoramic digital image correlation and compared to local geometry and histology. Diameter correlated mildly with elastin grade and collagen, when considering all circumferential locations and remodeling times. Normalized wall thickness correlated strongly with normalized collagen area fraction, though with outliers in highly cellular regions. Circumferential Green strain correlated strongly with elastin grade when measured over the range of 20-140 mmHg, though the correlation weakened across a physiologic range of 80-120 mmHg. Axial strain correlated strongly between in vitro and physiologic ranges of pressures. Circumferential heterogeneities render diameter a poor predictor of underlying regional microstructure. Thickness may indicate collagen content, though corrections are needed in regions of increased cellularity. In vitro circumferential strain predicts local functional elastin over large ranges of pressure, but there is a need to extend this correlation to clinically relevant pressures. Axial strain in the aneurysmal shoulder region may reflect the elastic integrity within the apical region of the lesion and should be explored as an indicator of disease severity.

Topics: Abdominal Wall; Animals; Aortic Aneurysm, Abdominal; Aortic Rupture; Collagen; Disease Models, Animal; Disease Progression; Elastin; Humans; Male; Mice; Mice, Inbred C57BL

Thrombomodulin (TM), through its lectin-like domain (TMD1), sequesters proinflammatory high-mobility group box 1 (HMGB1) to prevent it from engaging the receptor for advanced glycation end product (RAGE) that sustains inflammation and tissue damage. Our previous study demonstrated that short-term treatment with recombinant TM containing all the extracellular domains (i.e., rTMD123) inhibits HMGB1-RAGE signaling and confers protection against CaCl. The therapeutic effects of recombinant TMD1 (rTMD1) and recombinant AAV vectors carrying the lectin-like domain of TM (rAAV-TMD1) were evaluated in the CaCl. In the CaCl. These findings corroborate the therapeutic potential of the TM lectin-like domain in AAA. The attenuation of angiotensin II-infused AAA by one-time delivery of rAAV-TMD1 provides a proof-of-concept validation of its application as potential gene therapy for aneurysm development.

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Calcium Chloride; Cytokines; Dependovirus; Disease Models, Animal; Elastin; Genetic Therapy; Genetic Vectors; HMGB1 Protein; Macrophages; Male; Matrix Metalloproteinases; Mice, Knockout, ApoE; Oxidative Stress; Protein Domains; Receptor for Advanced Glycation End Products; Thrombomodulin; Vascular Remodeling

Abdominal aortic aneurysm (AAA) is a prevalent disease affecting around 5% of the population aged more than 65 years. The exact etiology and physiopathology of AAA still raises questions, and elective surgery is currently the only treatment option for this often progressive disease. In this study, we hypothesized and tested a pathophysiological model that depicts AAA as an inflammation-triggered autoimmune disease with remnant vessel wall peptide fragments as the antigen.. A pilot study with male AAA patients (n = 14) and male controls (n = 8) was conducted. In both study groups, peripheral blood monocytes and plasma were separated from whole blood by centrifugation. An ELISpot test was performed on cultured white blood cells for the presence of elastin-specific T-lymphocytes. An Enzyme-linked immuno sorbent assay (ELISA) was performed on plasma for the presence of elastin-specific IgG molecules.. ELISpot interferon-gamma secretion in AAA (7.7 ± 9.5%) and control (4.6 ± 3.5%) and ELISA anti-elastin IgG titer in AAA (77.5 ± 17.8%) and control (78.2 ± 31.5%) were not significantly different (P = 0.94 and P = 0.55, respectively). Both results are expressed as a percentage relative to the respective positive and negative control.. The results of our pilot study did not indicate a clear and invariable autoimmune process directed against remnant elastin peptide fragments. Further research into the model mechanics and a possible antigen is still necessary. In the mean time, the model as presented here already offers a pathophysiological framework to further research into the possible remnant epitope-driven AAA etiology.

Topics: Adult; Aged; Aortic Aneurysm, Abdominal; Autoantibodies; Autoimmunity; Case-Control Studies; Cells, Cultured; Elastin; Enzyme-Linked Immunospot Assay; Epitopes; Humans; Immunoglobulin G; Interferon-gamma Release Tests; Male; Peptide Fragments; Pilot Projects; T-Lymphocytes

Abdominal aortic aneurysm (AAA) is a vascular disease involving gradual dilation of the abdominal aorta. Recent studies suggest that nicotine, which is a primary component in cigarette smoke, is closely associated with the development and rupture of an AAA. Nicotine accelerates AAA development through the weakening of the vascular wall by increasing oxidative stress and matrix metalloproteinase (MMP)-2 expression. However, little is known about preventing the AAA induced by nicotine. A non-surgical means of preventing the weakening of the vascular wall before the onset of AAA by functional food factors would be a valuable option over surgery. Fish oil is a functional food that is rich in n-3 polyunsaturated fatty acids that have an anti-inflammatory effect. In this study, we evaluated the effect of dietary fish oil on the weakening of the aortic wall due to nicotine administration in a mouse model. Histological analysis showed that the dietary fish oil suppressed the degradation of elastin fibers in the nicotine-administered mice. Additionally, the dietary fish oil suppressed the protein level of MMP-12, macrophage infiltration, and the oxidative stress in the vascular wall. These results suggest that fish oil could suppress the weakening of the vascular wall by suppressing the elastin fiber degradation caused by nicotine. By suppressing the nicotine induced weakening of the vascular wall, fish oil might help prevent the development of AAA.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Eicosapentaenoic Acid; Elastin; Fish Oils; Humans; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice; Mice, Inbred C57BL; Nicotine; Oxidative Stress; Proteolysis

Spatiotemporal changes in the extracellular matrix (ECM) were studied within abdominal aortic aneurysms (AAAs) generated in rats via elastase infusion. At 7, 14 and 21 days post-induction, AAA tissues were divided into proximal, mid- and distal regions, based on their location relative to the renal arteries and the region of maximal aortic diameter. Wall thicknesses differed significantly between the AAA spatial regions, initially increasing due to positive matrix remodelling and then decreasing due to wall thinning and compaction of matrix as the disease progressed. Histological images analysed using custom segmentation tools indicated significant differences in ECM composition and structure vs healthy tissue, and in the extent and nature of matrix remodelling between the AAA spatial regions. Histology and immunofluorescence (IF) labelling provided evidence of neointimal AAA remodelling, characterized by presence of elastin-containing fibres. This remodelling was effected by smooth muscle α-actin-positive neointimal cells, which transmission electron microscopy (TEM) showed to differ morphologically from medial SMCs. TEM of the neointima further showed the presence of elongated deposits of amorphous elastin and the presence of nascent, but not mature, elastic fibres. These structures appeared to be deficient in at least one microfibrillar component, fibrillin-1, which is critical to mature elastic fibre assembly. The substantial production of elastin and elastic fibre-like structures that we observed in the AAA neointima, which was not observed elsewhere within AAA tissues, provides a unique opportunity to capitalize on this autoregenerative phenomenon and direct it from the standpoint of matrix organization towards restoring healthy aortic matrix structure, mechanics and function. Copyright © 2014 John Wiley & Sons, Ltd.

Topics: Actins; Animals; Aorta; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elastic Tissue; Elastin; Extracellular Matrix; Fluorescent Antibody Technique; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Pancreatic Elastase; Phenotype; Rats; Rats, Sprague-Dawley; Regeneration; Spatio-Temporal Analysis

Abdominal aortic aneurysms (AAAs) involve slow proteolysis and loss of structural matrix components (collagen and elastin), which lead to wall thinning, weakening and ultimate rupture. At this time, no established non-surgical therapy is available to slow or arrest AAA growth. Inhibiting matrix metalloproteases (MMPs; e.g. MMP2 and -9) overexpressed within AAAs is insufficient to arrest AAA growth, since resident smooth muscle cells (SMCs) are poorly elastogenic and cannot overcome elastolysis to reinstate a healthy elastic matrix. Towards overcoming this limitation, this first study sought to determine the utility of rat bone marrow mesenchymal stem cell (BM-MSC)-derived SMCs to stimulate elastin and elastic matrix synthesis and assembly by aneurysmal SMCs (EaRASMCs). BM-MSCs were successfully differentiated into cells of an SMC lineage (SMLCs). Our study indicates that BM-MSC-derived SMLCs secrete trophic factors, contained in conditioned medium (CM) from their cultures, that, when exposed to EaRASMC cultures in real time, stimulate elastin precursor and matrix deposition and crosslinking by these elastogenically deficient cells, with added benefits in terms of attenuating MMPs, specifically MMP9. The results thus lend support to a proposed cell therapy for AAAs, based on the use of BM-MSC-derived SMLCs. Although we observed no particular improvement in elastic fibre formation, no attenuation of MMP2 activity and increase in amounts of active MMP2 enzyme, we believe that this study justifies follow-up studies to improve upon these outcomes. Future studies will explore the effects of concentrated CM collected from long-term SMLC cultures on EaRASMCs and also investigate the elastogenic output of SMLCs themselves. Copyright © 2014 John Wiley & Sons, Ltd.

Topics: Animals; Aortic Aneurysm, Abdominal; Bone Marrow Cells; Cell Differentiation; Cell Lineage; Cells, Cultured; Collagen; Culture Media, Conditioned; Elastin; Extracellular Matrix; Flow Cytometry; Fluorescent Antibody Technique; Gene Expression Regulation; Matrix Metalloproteinase 2; Mesenchymal Stem Cells; Myocytes, Smooth Muscle; Paracrine Communication; Rats, Sprague-Dawley

Inflammation-mediated elastin destruction in the aortic medial layer is related to progression of abdominal aortic aneurysm (AAA). Epigallocatechin-3-gallate (EGCG), a major component of green tea polyphenols, reportedly increases elastin synthesis in vitro and may possess anti-inflammatory effects. We used a rat model to investigate whether EGCG could prevent AAA progression.. The abdominal aortic diameter was significantly smaller in the EGCG group than in the control group on day 28 (2.9 ± 0.2 vs 2.3 ± 0.1 mm; P < .0001). The medial layer wall thickness and elastin content were significantly greater in the EGCG group than in the control group on day 28 (68.4 ± 13.6 vs 46.7 ± 13.4 μm [P < .001] and 20.3 ± 4.6 vs 9.5 ± 3.6% [P < .0001], respectively). Gene expression levels of tropoelastin and lysyl oxidase were significantly higher in the EGCG group immediately before AAA induction, indicating promoted elastoregeneration by EGCG administration (tropoelastin: 0.59 ± 0.36 control vs 1.24 ± 0.36 EGCG [P < .05], lysyl oxidase: 0.77 ± 0.45 control vs 1.34 ± 0.4 EGCG [P < .05]) (fold increase). Gene expression levels of inflammatory cytokines, including tumor necrosis factor-α and interleukin-1β, were significantly downregulated in the EGCG group (1.82 ± 0.71 vs 0.97 ± 0.59 [P < .05] and 3.91 ± 3.24 vs 0.89 ± 0.59 [P < .05], respectively). On day 7, gene expression levels and gelatinolytic activity of matrix metalloproteinase 9 were significantly lower in the EGCG group (1.41 ± 0.86 vs 0.51 ± 0.42 [P < .05] and 1.00 ± 0.17 vs 0.29 ± 0.12 [P < .0001], respectively), whereas gene expression levels of tissue inhibitors of metalloproteinase-1 were significantly higher in the EGCG group (0.96 ± 0.11 vs 1.14 ± 0.09; P < .05).. EGCG attenuated AAA progression in a rat model by preserving the aortic thickness and elastin content of the medial layer through regeneration of elastin, as mediated by anti-inflammatory effects, and subsequent reduction of matrix metalloproteinase activity.

Topics: Administration, Oral; Animals; Anti-Inflammatory Agents; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Calcium Chloride; Catechin; Collagen; Cytokines; Dilatation, Pathologic; Disease Models, Animal; Disease Progression; Elastin; Gene Expression Regulation; Inflammation Mediators; Male; Matrix Metalloproteinase 1; Matrix Metalloproteinase 9; Pancreatic Elastase; Phytotherapy; Plant Extracts; Plants, Medicinal; Polyphenols; Protein-Lysine 6-Oxidase; Rats, Sprague-Dawley; Tea; Time Factors; Tropoelastin

Atherosclerosis and aneurysms are leading causes of mortality worldwide. MicroRNAs (miRs) are key determinants of gene and protein expression, and atypical miR expression has been associated with many cardiovascular diseases; although their contributory role to atherosclerotic plaque and abdominal aortic aneurysm stability are poorly understood.. To investigate whether miR-181b regulates tissue inhibitor of metalloproteinase-3 expression and affects atherosclerosis and aneurysms.. Here, we demonstrate that miR-181b was overexpressed in symptomatic human atherosclerotic plaques and abdominal aortic aneurysms and correlated with decreased expression of predicted miR-181b targets, tissue inhibitor of metalloproteinase-3, and elastin. Using the well-characterized mouse atherosclerosis models of Apoe. Our findings suggest that the management of miR-181b and its target genes provides therapeutic potential for limiting the progression of atherosclerosis and aneurysms and protecting them from rupture.

Topics: Animals; Aortic Aneurysm, Abdominal; Atherosclerosis; Diet, High-Fat; Elastin; Female; Humans; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; MicroRNAs; Middle Aged; Tissue Inhibitor of Metalloproteinase-3

Abdominal aortic aneurysm (AAA) is a life-threatening vascular pathology, the pathogenesis of which is closely related to oxidative stress. However, an effective pharmaceutical treatment is lacking because the exact cause of AAA remains unknown. Here, we aimed at delineating the role of the paraoxonases (PONs) gene cluster (PC), which prevents atherosclerosis through the detoxification of oxidized substrates, in AAA formation.. PC transgenic (Tg) mice were crossed to an Apoe. Our findings reveal, for the first time, a protective role of the PC in AAA formation and suggest PONs as promising targets for AAA prevention.

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; Aryldialkylphosphatase; Cells, Cultured; Disease Models, Animal; Elastin; Extracellular Matrix; Genetic Predisposition to Disease; Humans; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Multigene Family; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Oxidative Stress; Phenotype; Proteolysis; Reactive Oxygen Species; Signal Transduction

MicroRNA-145 (miR-145) has been implicated in vascular smooth muscle cell differentiation, but the underlying mechanisms have not been fully understood, especially their role in abdominal aortic aneurysm (AAA) expansion. Here, we sought to explore and define the mechanisms of miR-145 function in the experimental AAA models in AngII-infused ApoE. miR-145 was overexpressed in ApoE. In vivo overexpression of miR-145 by lentivirus infection greatly decreased the incidence of AAA, maximum abdominal aortic diameter, and elastin degradation, accompanied with downregulation of MMP2 activation in AngII-infused ApoE. These data suggest that regulation of expression of miR-145 may be a potential therapeutic option for vascular disease progression such as AAA expansion.

Topics: Angiotensin II; Animals; Aortic Aneurysm, Abdominal; Apolipoproteins E; Collagen; Disease Models, Animal; Elastin; Gene Expression Regulation, Enzymologic; Lentivirus; Matrix Metalloproteinase 2; Mice; Mice, Knockout; MicroRNAs; Transduction, Genetic; Up-Regulation

Abdominal aortic aneurysm (AAA) is a degenerative disease of the aorta characterized by severe disruption of the structural integrity of the aortic wall and its major molecular constituents. From the early stages of disease, elastin in the aorta becomes highly degraded and is replaced by collagen. Questions persist as to the contribution of collagen content, quality and maturity to the potential for rupture. Here, using our recently developed Fourier transform infrared imaging spectroscopy (FT-IRIS) method, we quantified collagen content and maturity in the wall of AAA tissues in pairs of specimens with different wall stresses. CT scans of AAAs from 12 patients were used to create finite element models to estimate stress in different regions of tissue. Each patient underwent elective repair of the AAA, and two segments of the AAA tissues from anatomic regions more proximal or distal with different wall stresses were evaluated by histology and FT-IRIS after excision. For each patient, collagen content was generally greater in the tissue location with lower wall stress, which corresponded to the more distal anatomic regions. The wall stress/collagen ratio was greater in the higher stress region compared to the lower stress region (1.01 ± 1.09 vs. 0.55 ± 0.084, p = 0.02). The higher stress region also corresponded to the location with reduced intraluminal thrombus thickness. Further, collagen maturity tended to decrease with increased collagen content (p = 0.068, R = 0.38). Together, these results suggest that an increase in less mature collagen content in AAA patients does not effectively compensate for the loss of elastin in the aortic wall, and results in a reduced capability to endure wall stresses.

Topics: Aorta, Abdominal; Aortic Aneurysm, Abdominal; Collagen; Elastin; Extracellular Matrix; Humans; Spectroscopy, Fourier Transform Infrared; Stress, Mechanical

Abdominal aortic aneurysm (AAA) is a common aortic disease with a progressive nature. There is no approved pharmacological treatment to effectively slow aneurysm growth or prevent rupture. Necroptosis is a form of programmed necrosis that is regulated by receptor-interacting protein kinases (RIPs). We have recently demonstrated that the lack of RIP3 in mice prevented aneurysm formation. The goal of the current study is to test whether perturbing necroptosis affects progression of existing aneurysm using the RIP1 inhibitors Necrostatin-1 (Nec-1) and an optimized form of Nec-1, 7-Cl-O-Nec-1 (Nec-1s). Seven days after aneurysm induction by elastase perfusion, mice were randomly administered DMSO, Nec-1 (3.2 mg/kg/day) and Nec-1s (1.6 mg/kg/day) via intraperitoneal injection. Upon sacrifice on day 14 postaneurysm induction, the aortic expansion in the Nec-1s group (64.12 ± 4.80%) was significantly smaller than that of the DMSO group (172.80 ± 13.68%) (P < 0.05). The mean aortic diameter of Nec-1 treated mice appeared to be smaller (121.60 ± 10.40%) than the DMSO group, though the difference was not statistically significant (P = 0.1). Histologically, the aortic structure of Nec-1s-treated mice appeared normal, with continuous and organized elastin laminae and abundant αActin-expressing SMCs. Moreover, Nect-1s treatment diminished macrophage infiltration and MMP9 accumulation and increased aortic levels of tropoelastin and lysyl oxidase. Together, our data suggest that pharmacological inhibition of necroptosis with Nec-1s stabilizes pre-existing aneurysms by diminishing inflammation and promoting connective tissue repair.

Topics: Animals; Anti-Inflammatory Agents; Aortic Aneurysm, Abdominal; Apoptosis; Cardiovascular Agents; Cell Movement; Disease Models, Animal; Elastin; Gene Expression Regulation; GTPase-Activating Proteins; Humans; Imidazoles; Indoles; Injections, Intraperitoneal; Macrophages; Male; Matrix Metalloproteinase 9; Mice; Mice, Inbred C57BL; Myocytes, Smooth Muscle; Necrosis; Pancreatic Elastase; Protein-Lysine 6-Oxidase; Tropoelastin

MicroRNAs (miRNAs or miRs) have been highlighted to be involved in abdominal aortic aneurysm (AAA) with the emergence of recent miRNA microarray profiling studies. miR-516a-5p has been shown to be significantly overexpressed in vascular smooth muscle cells (VSMCs) from human AAA tissues from our previous microarray study, suggesting its crucial association with AAA. In addition, further bioinformatics analysis predicted methylenetetrahydrofolate reductase (MTHFR), which regulates homocysteine (Hcy) metabolism and is proposed to be a risk gene for AAA formation and to be the downregulation target of miR-516a-5p. However, the pathogenic role of miR-516a-5p in VSMCs for AAA formation remains unresolved. This study aims to investigate the role of miR-516a-5p in human VSMCs for AAA pathogenesis.. miR-516a-5p was stably overexpressed and knocked down in VSMCs explant cultured from human abdominal aortic tissues by means of lentiviral system. The MTHFR protein expression was first examined by Western blotting. In addition, the protein expressions of several key components involved in AAA pathogenic features are as follows: matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitor of matrix metalloproteinase (TIMP)-1 and TIMP-2 for elastin degradation; collagen type 1 alpha 1 for compensatory collagen synthesis; monocyte chemoattractant protein-1 for inflammation, were also evaluated. Apoptotic level of VSMCs was examined by terminal deoxynucleotidyl transferase dUTP nick end labeling assay.. Results showed that protein expression of MTHFR was significantly downregulated on miR-516a-5p overexpression (P < 0.05) in VSMCs, whereas it was significantly upregulated on miR-516a-5p knockdown (P < 0.05). Of all the AAA key components investigated, only MMP-2 and TIMP-1 protein expressions were found altered. A significant increase in MMP-2 (P < 0.05) and decrease in TIMP-1 (P < 0.05) expressions were observed on miR-516a-5p overexpression in VSMCs. Apoptosis was not promoted on miR-516a-5p overexpression or knockdown in VSMCs.. Our findings suggested that miR-516a-5p may regulate MTHFR, MMP-2, and TIMP-1 expressions in human VSMCs, possibly promoting the disruption of Hcy metabolism and proteolytic degradation of elastin for AAA formation.

Topics: Adult; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apoptosis; Cells, Cultured; Elastin; Homocysteine; Humans; Male; Matrix Metalloproteinase 2; Methylenetetrahydrofolate Reductase (NADPH2); MicroRNAs; Middle Aged; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Proteolysis; RNA Interference; Signal Transduction; Tissue Inhibitor of Metalloproteinase-1; Transfection

Chronic inflammation and degradation of elastin are the main processes in the development of abdominal aortic aneurysm (AAA). Recent studies show that zinc has an anti-inflammatory effect. Based on these, zinc may render effective therapy for the treatment of the AAA. Currently, we want to investigate the effects of zinc on AAA progression and its related molecular mechanism. Rat AAA models were induced by periaortic application of CaCl2. AAA rats were treated by daily intraperitoneal injection of ZnSO4 or vehicle alone. The aorta segments were collected at 4 weeks after surgery. The primary rat aortic vascular smooth muscle cells (VSMCs) were stimulated with TNF-α alone or with ZnSO4 for 3 weeks. The results showed that zinc supplementation significantly suppressed the CaCl2-induced expansion of the abdominal aortic diameter, as well as a preservation of medial elastin fibers in the aortas. Zinc supplementation also obviously attenuated infiltration of the macrophages and lymphocytes in the aortas. In addition, zinc reduced MMP-2 and MMP-9 production in the aortas. Most importantly, zinc treatment significantly induced A20 expression, along with inhibition of the NF-κB canonical signaling pathway in vitro in VSMCs and in vivo in rat AAA. This study demonstrated, for the first time, that zinc supplementation could prevent the development of rat experimental AAA by induction of A20-mediated inhibition of the NF-κB canonical signaling pathway.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Cells, Cultured; Disease Models, Animal; DNA-Binding Proteins; Elastin; I-kappa B Kinase; I-kappa B Proteins; Inflammation; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors; Myocytes, Smooth Muscle; NF-kappa B; NF-KappaB Inhibitor alpha; Rats; Rats, Wistar; Signal Transduction; Tumor Necrosis Factor alpha-Induced Protein 3; Zinc Sulfate

Kawasaki disease (KD) is the most common cause of acquired cardiac disease in US children. In addition to coronary artery abnormalities and aneurysms, it can be associated with systemic arterial aneurysms. We evaluated the development of systemic arterial dilatation and aneurysms, including abdominal aortic aneurysm (AAA) in the Lactobacillus casei cell-wall extract (LCWE)-induced KD vasculitis mouse model.. We discovered that in addition to aortitis, coronary arteritis and myocarditis, the LCWE-induced KD mouse model is also associated with abdominal aorta dilatation and AAA, as well as renal and iliac artery aneurysms. AAA induced in KD mice was exclusively infrarenal, both fusiform and saccular, with intimal proliferation, myofibroblastic proliferation, break in the elastin layer, vascular smooth muscle cell loss, and inflammatory cell accumulation in the media and adventitia. Il1r(-/-), Il1a(-/-), and Il1b(-/-) mice were protected from KD associated AAA. Infiltrating CD11c(+) macrophages produced active caspase-1, and caspase-1 or NLRP3 deficiency inhibited AAA formation. Treatment with interleukin (IL)-1R antagonist (Anakinra), anti-IL-1α, or anti-IL-1β mAb blocked LCWE-induced AAA formation.. Similar to clinical KD, the LCWE-induced KD vasculitis mouse model can also be accompanied by AAA formation. Both IL-1α and IL-1β play a key role, and use of an IL-1R blocking agent that inhibits both pathways may be a promising therapeutic target not only for KD coronary arteritis, but also for the other systemic arterial aneurysms including AAA that maybe seen in severe cases of KD. The LCWE-induced vasculitis model may also represent an alternative model for AAA disease.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortitis; Caspase 1; Cell Proliferation; Cell Wall; Dilatation, Pathologic; Disease Models, Animal; Elastin; Female; Gene Expression Profiling; Genotype; Humans; Interleukin 1 Receptor Antagonist Protein; Interleukin-1alpha; Interleukin-1beta; Lacticaseibacillus casei; Macrophages; Male; Mice, Inbred C57BL; Mice, Knockout; Mucocutaneous Lymph Node Syndrome; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; NLR Family, Pyrin Domain-Containing 3 Protein; Phenotype; Receptors, Interleukin-1 Type I; Signal Transduction; Time Factors

Abdominal aortic aneurysm (AAA) is a major cause of morbidity and mortality; however, the mechanisms that are involved in disease initiation and progression are incompletely understood. Extracellular matrix proteins play an integral role in modulating vascular homeostasis in health and disease. Here, we determined that the expression of the matricellular protein CCN3 is strongly reduced in rodent AAA models, including angiotensin II-induced AAA and elastase perfusion-stimulated AAA. CCN3 levels were also reduced in human AAA biopsies compared with those in controls. In murine models of induced AAA, germline deletion of Ccn3 resulted in severe phenotypes characterized by elastin fragmentation, vessel dilation, vascular inflammation, dissection, heightened ROS generation, and smooth muscle cell loss. Conversely, overexpression of CCN3 mitigated both elastase- and angiotensin II-induced AAA formation in mice. BM transplantation experiments suggested that the AAA phenotype of CCN3-deficient mice is intrinsic to the vasculature, as AAA was not exacerbated in WT animals that received CCN3-deficient BM and WT BM did not reduce AAA severity in CCN3-deficient mice. Genetic and pharmacological approaches implicated the ERK1/2 pathway as a critical regulator of CCN3-dependent AAA development. Together, these results demonstrate that CCN3 is a nodal regulator in AAA biology and identify CCN3 as a potential therapeutic target for vascular disease.

Topics: Angiotensin II; Animals; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elastin; Gene Deletion; Humans; MAP Kinase Signaling System; Mice; Mice, Knockout; Nephroblastoma Overexpressed Protein; Pancreatic Elastase

Clinical management of abdominal aortic aneurysm (AAA) is currently limited to elective surgical repair because an effective pharmacotherapy is still awaited. Inhibition of histone deacetylase (HDAC) activity could be a promising therapeutic option in cardiovascular diseases. We aimed to characterise HDAC expression in human AAA and to evaluate the therapeutic potential of class I and IIa HDAC inhibitors in the AAA model of angiotensin II (Ang II)-infused apolipoprotein-E-deficient (ApoE(-/-)) mice. Real-time PCR, western blot and immunohistochemistry evidenced an increased expression of HDACs 1, 2 (both class I), 4 and 7 (both class IIa) in abdominal aorta samples from patients undergoing AAA open repair (n=22) compared with those from donors (n=14). Aortic aneurysms from Ang-II-infused ApoE(-/-) mice exhibited a similar HDAC expression profile. In these animals, treatment with a class I HDAC inhibitor (MS-275) or a class IIa inhibitor (MC-1568) improved survival, reduced the incidence and severity of AAA and limited aneurysmal expansion evaluated by Doppler ultrasonography. These beneficial effects were more potent in MC-1568-treated mice. The disorganisation of elastin and collagen fibres and lymphocyte and macrophage infiltration were effectively reduced by both inhibitors. Additionally, HDAC inhibition attenuated the exacerbated expression of pro-inflammatory markers and the increase in metalloproteinase-2 and -9 activity induced by Ang II in this model. Therefore, our data evidence that HDAC expression is deregulated in human AAA and that class-selective HDAC inhibitors limit aneurysm expansion in an AAA mouse model. New-generation HDAC inhibitors represent a promising therapeutic approach to overcome human aneurysm progression.

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; Biomarkers; Collagen; Disease Models, Animal; Disease Progression; Elastin; Enzyme Induction; Female; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; Inflammation; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Middle Aged; Severity of Illness Index; Up-Regulation

Loss of integrity and massive disruption of elastic fibers are key features of abdominal aortic aneurysm (AAA). Peroxisome proliferator-activated receptor γ (PPARγ) has been shown to attenuate AAA through inhibition of inflammation and proteolytic degradation. However, its involvement in elastogenesis during AAA remains unclear. PPARγ was highly expressed in human AAA within all vascular cells, including inflammatory cells and fibroblasts. In the aortas of transgenic mice expressing PPARγ at 25% normal levels (Pparg(C) (/-) mice), we observed the fragmentation of elastic fibers and reduced expression of vital elastic fiber components of elastin and fibulin-5. These were not observed in mice with 50% normal PPARγ expression (Pparg(+/-) mice). Infusion of a moderate dose of angiotensin II (500 ng/kg per minute) did not induce AAA but Pparg(+/-) aorta developed flattened elastic lamellae, whereas Pparg(C/-) aorta showed severe destruction of elastic fibers. After infusion of angiotensin II at 1000 ng/kg per minute, 73% of Pparg(C/-) mice developed atypical suprarenal aortic aneurysms: superior mesenteric arteries were dilated with extensive collagen deposition in adventitia and infiltrations of inflammatory cells. Although matrix metalloproteinase inhibition by doxycycline somewhat attenuated the dilation of aneurysm, it did not reduce the incidence nor elastic lamella deterioration in angiotensin II-infused Pparg(C/-) mice. Furthermore, PPARγ antagonism downregulated elastin and fibulin-5 in fibroblasts, but not in vascular smooth muscle cells. Chromatin immunoprecipitation assay demonstrated PPARγ binding in the genomic sequence of fibulin-5 in fibroblasts. Our results underscore the importance of PPARγ in AAA development though orchestrating proper elastogenesis and preserving elastic fiber integrity.

Topics: Analysis of Variance; Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Cells, Cultured; Disease Models, Animal; Elastin; Gene Expression Regulation; Humans; Inflammation; Male; Matrix Metalloproteinases; Mice; Mice, Knockout; Middle Aged; Muscle, Smooth, Vascular; PPAR gamma

Abdominal aortic aneurysm is a dynamic vascular disease characterized by inflammatory cell invasion and extracellular matrix degradation. Damage to elastin in the extracellular matrix results in release of elastin-derived peptides (EDPs), which are chemotactic for inflammatory cells such as monocytes. Their effect on macrophage polarization is less well known. Proinflammatory M1 macrophages initially are recruited to sites of injury, but, if their effects are prolonged, they can lead to chronic inflammation that prevents normal tissue repair. Conversely, anti-inflammatory M2 macrophages reduce inflammation and aid in wound healing. Thus, a proper M1/M2 ratio is vital for tissue homeostasis. Abdominal aortic aneurysm tissue reveals a high M1/M2 ratio in which proinflammatory cells and their associated markers dominate. In the current study, in vitro treatment of bone marrow-derived macrophages with EDPs induced M1 macrophage polarization. By using C57BL/6 mice, Ab-mediated neutralization of EDPs reduced aortic dilation, matrix metalloproteinase activity, and proinflammatory cytokine expression at early and late time points after aneurysm induction. Furthermore, direct manipulation of the M1/M2 balance altered aortic dilation. Injection of M2-polarized macrophages reduced aortic dilation after aneurysm induction. EDPs promoted a proinflammatory environment in aortic tissue by inducing M1 polarization, and neutralization of EDPs attenuated aortic dilation. The M1/M2 imbalance is vital to aneurysm formation.

Topics: Animals; Antibodies, Monoclonal; Aortic Aneurysm, Abdominal; Elastin; Macrophage Activation; Macrophages; Male; Mice; Mice, Inbred C57BL; Peptide Fragments

To study the role of lipocalin-2 (Lcn2) and the effect of Lcn2 blockade via anti-Lcn2 antibody in the development of abdominal aortic aneurysm (AAA).. Expression mRNA and protein levels of Lcn2 and its human orthologue neutrophil gelatinase-associated lipocalin (NGAL) in aortic wall samples from experimental mouse and human AAA samples, respectively, were analysed by real-time PCR and immunohistochemistry. Experimental AAA was induced by aortic elastase perfusion in wild-type mice (WT) and Lcn2-deficient mice (Lcn2-/-). NGAL/Lcn2 mRNA and protein levels in human and murine AAA samples were increased compared with healthy aortas. Decreased AAA incidence and reduced aortic expansion were observed in Lcn2-/- mice or mice preoperative treated with a polyclonal anti-Lcn2 antibody compared with WT mice or mice treated with control IgG, respectively, at Day 14 after elastase perfusion. Moreover, immunohistochemical analysis of AAA tissues from Lcn2-/- or anti-Lcn2-treated mice showed diminished elastin damage, reduced microvessels and polymorphonuclear neutrophil (PMN) infiltration, and enhanced preservation of vascular smooth muscle cells compared with WT aortas. Fluorescent molecular tomography revealed decreased MMP activity in AAA of Lcn2-/- mice compared with WT controls. Therapeutic administration of anti-Lcn2 antibody to WT mice 3 days after elastase perfusion decreased aortic dilatation and PMN infiltration compared with WT mice treated with control IgG.. Either Lcn2 deficiency or anti-Lcn2 antibody blockade limits AAA expansion in mice by decreasing PMN infiltration in the aorta. Lcn2 modulation may therefore be a viable new therapeutic option for the treatment of AAA.

Topics: Animals; Antibodies; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Case-Control Studies; Cells, Cultured; Chemotaxis, Leukocyte; Dilatation, Pathologic; Disease Models, Animal; Elastin; Genetic Predisposition to Disease; Humans; Lipocalin-2; Matrix Metalloproteinases; Mice, Inbred C57BL; Mice, Knockout; Microvessels; Muscle, Smooth, Vascular; Neutrophil Infiltration; Phenotype; RNA, Messenger; Time Factors

An abdominal aortic aneurysm (AAA) is a permanent, localized dilatation of the abdominal aorta. In western countries, the morbidity of AAA is approximately 8%. Currently, pharmacotherapies for AAA are limited. Here, we demonstrate that baicalein (BAI), the main component of the Chinese traditional drug "Huang Qin", attenuates the incidence and severity of AAA in Apoe (-/-) mice infused with angiotensin II (AngII). Mechanically, BAI treatment decreases AngII-induced reactive oxygen species (ROS) production in the aortic wall. Moreover, BAI inhibits inflammatory cell accumulation in the aortas of mice infused with AngII. It also inhibits AngII-induced activation of matrix metalloproteinase 2 (MMP-2) and MMP-9 to maintain elastin content in vivo. In addition, it blocks AngII cascade by downregulating angiotensin type 1 receptor (AT1R) and inhibiting mitogen-activated protein kinases (MAPKs). Taken together, our findings show that BAI is an effective agent for AAA prevention.

Topics: Angiotensin II; Animals; Antioxidants; Aortic Aneurysm, Abdominal; Apolipoproteins E; Blotting, Western; Elastin; Flavanones; Immunohistochemistry; JNK Mitogen-Activated Protein Kinases; Male; MAP Kinase Signaling System; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice, Inbred C57BL; Mice, Knockout; p38 Mitogen-Activated Protein Kinases; Protective Agents; Reactive Oxygen Species; Receptor, Angiotensin, Type 1

Degeneration of elastin plays a vital role in the pathology and progression of abdominal aortic aneurysm (AAA). Our previous study showed that pentagalloyl glucose (PGG), a core derivative of tannic acid, hinders the development of AAAs in a clinically relevant animal model when applied locally. In this study, we tested whether targeted nanoparticles (NPs) can deliver PGG to the site of an aneurysm and prevent aneurysmal growth by protecting elastin. PGG-loaded albumin NPs with a surface-conjugated elastin-specific antibody were prepared. Aneurysms were induced by calcium chloride-mediated injury to the abdominal aorta in rats. NPs were injected into the tail vein after 10 days of CaCl

Topics: Animals; Antibodies; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Calcium Chloride; Cells, Cultured; Cytoprotection; Disease Models, Animal; Drug Compounding; Drug Liberation; Elastic Tissue; Elastin; Hydrolyzable Tannins; Injections, Intravenous; Macrophages; Male; Matrix Metalloproteinases; Nanoparticles; Particle Size; Proteolysis; Rats, Sprague-Dawley; Solubility; Vascular Calcification

Aortic aneurysm is a disastrous vascular disease with high morbidity and mortality. Matrix metalloproteinases (MMPs), especially MMP-9, is implicated in the development of aortic aneurysm, but the effective MMP inhibitors are far from development. To develop new candidate compound for aortic aneurysm therapy, we evaluated the effects of salvianolic acid C (SalC) against the formation of aortic aneurysm.. Aortic aneurysm was induced by implantation of angiotension II (AngII) minipump in apolipoprotein E-deficient (ApoE. SalC significantly ameliorated the progression of aortic aneurysm in ApoE

Topics: Alkenes; Animals; Aorta; Aortic Aneurysm; Aortic Aneurysm, Abdominal; Apolipoproteins E; Elastin; Gene Deletion; Humans; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors; Mice, Inbred C57BL; Polyphenols

The purpose of this study was to evaluate the diameter and thickness-related variations in mechanical properties of degraded arterial wall. To this end, ring tests were performed on 31 samples from the rat xenograft model of abdominal aortic aneurysm (AAA) and failure properties were determined. An inverse finite element method was then employed to identify the material parameters of a hyperelastic and incompressible strain energy function. Correlations with outer diameter and wall thickness of the rings were examined. Furthermore, we investigated the changes in mechanical properties between the grafts, which consist in guinea pig decellularized aortas, native murine aortas and degraded aortas (AAAs). Decellularized aortas presented a significantly lower ultimate strain associated with a higher stiffening rate compared to native aortas. AAAs exhibited a significantly lower ultimate stress than other groups and an extensible-but-stiff behavior. The proposed approach revealed correlations of ultimate stress and material parameters of aneurysmal aortas with outer diameter and thickness. In particular, the negative correlations of the material parameter accounting for the response of the non-collagenous matrix with diameter and thickness (r=-0.67 and r=-0.73, p<0.001) captured the gradual loss of elastin with dilatation observed in histology (r=-0.97, p<0.001). Moreover, it exposed the progressive weakening of the wall with enlargement and thickening (r=-0.64 and r=-0.69, p<0.001), suggesting that wall thickness and diameter may be indicators of rupture risk in the rat xenograft model.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Biomechanical Phenomena; Disease Models, Animal; Elastin; Finite Element Analysis; Guinea Pigs; Heterografts; Male; Models, Biological; Rats; Rats, Inbred F344

Low-density lipoprotein receptor-related protein 1 (LRP1), a multifunctional protein involved in endocytosis and cell signaling pathways, leads to several vascular pathologies when deleted in vascular smooth muscle cells (SMCs). The purpose of this study was to determine whether LRP1 deletion in SMCs influenced angiotensin II-induced arterial pathologies.. LRP1 protein abundance was equivalent in selected arterial regions, but SMC-specific LRP1 depletion had no effect on abdominal and ascending aortic diameters in young mice. To determine the effects of LRP1 deficiency on angiotensin II vascular responses, SMC-specific LRP1 (smLRP1(+/+)) and smLRP1-deficient (smLRP1(-/-)) mice were infused with saline, angiotensin II, or norepinephrine. Several smLRP(-/-) mice died of superior mesenteric arterial (SMA) rupture during angiotensin II infusion. In surviving mice, angiotensin II profoundly augmented SMA dilation in smLRP1(-/-) mice. SMA dilation was blood pressure dependent as demonstrated by a similar response during norepinephrine infusion. SMA dilation was also associated with profound macrophage accumulation, but minimal elastin fragmentation. Angiotensin II infusion led to no significant differences in abdominal aorta diameters between smLRP1(+/+) and smLRP1(-/-) mice. In contrast, ascending aortic dilation was exacerbated markedly in angiotensin II-infused smLRP1(-/-) mice, but norepinephrine had no significant effect on either aortic region. Ascending aortas of smLRP1(-/-) mice infused with angiotensin II had minimal macrophage accumulation but significantly increased elastin fragmentation and mRNA abundance of several LRP1 ligands including MMP-2 (matrix metalloproteinase-2) and uPA (urokinase plasminogen activator).. smLRP1 deficiency had no effect on angiotensin II-induced abdominal aortic aneurysm formation. Conversely, angiotensin II infusion in smLRP1(-/-) mice exacerbated SMA and ascending aorta dilation. Dilation in these 2 regions had differential association with blood pressure and divergent pathological characteristics.

Topics: Aneurysm; Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm; Aortic Aneurysm, Abdominal; Arterial Pressure; Cells, Cultured; Dilatation, Pathologic; Disease Models, Animal; Elastin; Gene Deletion; Ligands; Low Density Lipoprotein Receptor-Related Protein-1; Macrophages; Male; Matrix Metalloproteinase 2; Mesenteric Artery, Superior; Mice, Knockout; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Norepinephrine; Receptors, LDL; RNA, Messenger; Tumor Suppressor Proteins; Urokinase-Type Plasminogen Activator

We propose a novel thick-walled fluid-solid-growth (FSG) computational framework for modeling vascular disease evolution. The arterial wall is modeled as a thick-walled nonlinearly elastic cylindrical tube consisting of two layers corresponding to the media-intima and adventitia, where each layer is treated as a fiber-reinforced material with the fibers corresponding to the collagenous component. Blood is modeled as a Newtonian fluid with constant density and viscosity; no slip and no-flux conditions are applied at the arterial wall. Disease progression is simulated by growth and remodeling (G&R) of the load bearing constituents of the wall. Adaptions of the natural reference configurations and mass densities of constituents are driven by deviations of mechanical stimuli from homeostatic levels. We apply the novel framework to model abdominal aortic aneurysm (AAA) evolution. Elastin degradation is initially prescribed to create a perturbation to the geometry which results in a local decrease in wall shear stress (WSS). Subsequent degradation of elastin is driven by low WSS and an aneurysm evolves as the elastin degrades and the collagen adapts. The influence of transmural G&R of constituents on the aneurysm development is analyzed. We observe that elastin and collagen strains evolve to be transmurally heterogeneous and this may facilitate the development of tortuosity. This multiphysics framework provides the basis for exploring the influence of transmural metabolic activity on the progression of vascular disease.

Topics: Algorithms; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Elastin; Finite Element Analysis; Humans; Hydrodynamics; Patient-Specific Modeling; Stress, Mechanical; Vascular Remodeling

Two-day infusion of angiotensin II to apolipoprotein E-deficient (ApoE(-/-)) mice provides a model of pre-abdominal aortic aneurysm. Long chain omega-3 polyunsaturated fatty acids (n-3 PUFAs) have anti-inflammatory effects. This study examined the effect of an eight-week low or high n-3 PUFA diet in ApoE(-/-) mice on matrix metalloproteinase (MMP) expression and elastin degradation.. ApoE(-/-) mice were fed a low or high n-3 PUFA diet for eight weeks prior to two-day infusion with angiotensin II. The omega-3 index, MMP-2, MMP-9, TIMP-1, and TGF-β1 immunoreactivity, and elastin fragmentation were measured.. The omega-3 index with the low and high n-3 PUFA diet was 3.78% and 13.03%, respectively. MMP-9 immunoreactive stain intensity was lower in mice fed the high, compared to the low n-3 PUFA diet in endothelial cells (suprarenal aorta), and inflammatory cells (suprarenal and infrarenal aorta). Inflammatory cells had higher TIMP-1 and TGF-β1 stain intensity in mice fed the high, compared to the low n-3 PUFA diet (suprarenal aorta). MMP-2 immunoreactivity was unaffected by diet. A non-significant trend for reduced elastin fragmentation was observed in mice fed the high n-3 PUFA diet.. Dietary supplementation with n-3 PUFAs may have protective anti-inflammatory effects mediated through modulation of MMPs and TIMPs.

Topics: Animals; Aortic Aneurysm, Abdominal; Apolipoproteins E; Dietary Supplements; Disease Models, Animal; Elastin; Fatty Acids, Omega-3; Gene Expression Regulation, Enzymologic; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice; Mice, Knockout; Transforming Growth Factor beta1

Interaction of the activating sequence in thrombospondin-1 (TSP-1) with the conserved sequence (leucine-serine-lysine-leucine [LSKL]) in the latency-associated peptide region of latent transforming growth factor (TGF)-β complex is important in regulating TGF-β1 activity. We aimed to assess the effect of blocking peptide LSKL on the progression of pre-established abdominal aortic aneurysm in angiotensin II-infused apolipoprotein E-deficient (ApoE(-/-)) mice.. Abdominal aortic aneurysm was established in 3-month-old male ApoE(-/-) mice with subcutaneous infusion of angiotensin II for 28 days. After this, mice received LSKL peptide or control SLLK (serine-leucine-leucine-lysine) peptide (4 mg/kg) via daily intraperitoneal injection for an additional 2 weeks. Administration of LSKL peptide promoted larger suprarenal aortic diameter, as determined by ultrasound and morphometric analysis, and stimulated more severe atherosclerosis within the aortic arch. In addition, mice receiving LSKL peptide exhibited elevated circulating proinflammatory cytokine levels and greater inflammatory cells within the suprarenal aorta compared with controls. Mice receiving LSKL peptide showed low plasma TGF-β1 activity and low levels of aortic tissue phosphorylated to total Smad2/3. Aortic gene expression of TGF-β receptor 1 (TGFBRI) and receptor 2 (TGFBRII), but not TGF-β1 and thrombospondin-1, were lower in mice receiving LSKL peptide than controls. LSKL peptide administration was associated with greater aortic elastin fragmentation and lower expression and activity of the TGF-β1-target gene lysyl oxidase like 1 (LOXL1).. Attenuation of thrombospondin-1-directed activation of TGF-β1 promotes abdominal aortic aneurysm and atherosclerosis progression in the angiotensin II-infused ApoE(-/-) mouse model.

Topics: Amino Acid Oxidoreductases; Angiotensin II; Animals; Aorta; Aortic Aneurysm, Abdominal; Apolipoproteins E; Atherosclerosis; Cytokines; Disease Models, Animal; Disease Progression; Elastin; Inflammation Mediators; Injections, Intraperitoneal; Male; Mice, Knockout; Peptides; Phosphorylation; Protein Serine-Threonine Kinases; Receptor, Transforming Growth Factor-beta Type I; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta; Smad2 Protein; Smad3 Protein; Thrombospondin 1; Time Factors; Transforming Growth Factor beta1

Maximum aortic diameter is an important measure in rupture prediction of abdominal aortic aneurysms (AAAs). Analyzing the variations of geometrical, material, and biochemical properties with increased AAA diameters advances understanding of the effect of lesion enlargement on patient specific vascular properties.. 96 AAA samples were harvested during open surgical aneurysm repair. Geometrical factors such as the maximum intraluminal thrombus (ILT) thickness, wall thickness, and AAA expansion rate were measured. Biaxial extension and peeling tests were performed to characterize the biaxial mechanical responses and to quantify the dissection properties of aneurysmal tissue. Mass fraction analysis quantified the dry weight percentages of elastin and collagen within the AAA wall. Linear regression models were used to correlate geometrical, mechanical, and mass fraction data with maximum AAA diameter.. Both ILT thickness and AAA expansion rate increased and were positively correlated with maximum AAA diameter, while there was a slight increase in wall thickness for AAAs with a larger maximum diameter. For the biaxial mechanical responses, mean peak stretches and maximum tangential moduli in the circumferential and longitudinal axes did not correlate with maximum AAA diameters. However, the quantified energy to propagate tissue dissections within intima-media composites showed a significant inverse correlation with maximum AAA diameter. Elastin content decreased significantly with increasing AAA diameter.. Larger AAA diameters are associated with thicker ILTs, higher AAA expansion rates, and pronounced elastin loss, and may also lead to a higher propensity for tissue dissection and aneurysm rupture.

Topics: Aged; Aged, 80 and over; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Rupture; Aortography; Biomechanical Phenomena; Collagen; Dilatation, Pathologic; Elastin; Female; Hemodynamics; Humans; Linear Models; Male; Middle Aged; Models, Cardiovascular; Regional Blood Flow; Retrospective Studies; Risk Assessment; Risk Factors; Stress, Mechanical; Tomography, X-Ray Computed

A computational framework to couple vascular growth and remodeling (G&R) with blood flow simulation in a 3D patient-specific geometry is presented. Hyperelastic and anisotropic properties are considered for the vessel wall material and a constrained mixture model is used to represent multiple constituents in the vessel wall, which was modeled as a membrane. The coupled simulation is divided into two time scales-a longer time scale for G&R and a shorter time scale for fluid dynamics simulation. G&R is simulated to evolve the boundary of the fluid domain, and fluid simulation is in turn used to generate wall shear stress and transmural pressure data that regulates G&R. To minimize required computation cost, the fluid dynamics are only simulated when G&R causes significant vascular geometric change. For demonstration, this coupled model was used to study the influence of stress-mediated growth parameters, and blood flow mechanics, on the behavior of the vascular tissue growth in a model of the infrarenal aorta derived from medical image data.

Topics: Aortic Aneurysm, Abdominal; Collagen; Computer Simulation; Elastin; Hemodynamics; Humans; Models, Cardiovascular; Neovascularization, Physiologic; Regional Blood Flow; Stress, Mechanical; Vascular Remodeling

Rupture of abdominal aortic aneurysm (AAA), a major cause of death in the aged population, is characterized by vascular inflammation and matrix degradation. Serum amyloid A (SAA), an acute-phase reactant linked to inflammation and matrix metalloproteinase induction, correlates with aortic dimensions before aneurysm formation in humans. We investigated whether SAA deficiency in mice affects AAA formation during angiotensin II (Ang II) infusion.. Plasma SAA increased ≈60-fold in apoE(-/-) mice 24 hours after intraperitoneal Ang II injection (100 μg/kg; n=4) and ≈15-fold after chronic 28-day Ang II infusion (1000 ng/kg per minute; n=9). AAA incidence and severity after 28-day Ang II infusion was significantly reduced in apoE(-/-) mice lacking both acute-phase SAA isoforms (SAAKO; n=20) compared with apoE(-/-) mice (SAAWT; n=20) as assessed by in vivo ultrasound and ex vivo morphometric analyses, despite a significant increase in systolic blood pressure in SAAKO mice compared with SAAWT mice after Ang II infusion. Atherosclerotic lesion area of the aortic arch was similar in SAAKO and SAAWT mice after 28-day Ang II infusion. Immunostaining detected SAA in AAA tissues of Ang II-infused SAAWT mice that colocalized with macrophages, elastin breaks, and enhanced matrix metalloproteinase activity. Matrix metalloproteinase-2 activity was significantly lower in aortas of SAAKO mice compared with SAAWT mice after 10-day Ang II infusion.. Lack of endogenous acute-phase SAA protects against experimental AAA through a mechanism that may involve reduced matrix metalloproteinase-2 activity.

Topics: Angiotensin II; Animals; Aortic Aneurysm, Abdominal; Apolipoproteins E; Biomarkers; Disease Models, Animal; Elastin; Macrophages; Matrix Metalloproteinase 2; Mice; Mice, Inbred C57BL; Mice, Knockout; Random Allocation; Sensitivity and Specificity; Serum Amyloid A Protein

TGF-β signaling plays critical roles in the pathogenesis of aneurysms; however, it is still unclear whether its role is protective or destructive. In this study, we investigate the role of SMAD3 in the pathogenesis of calcium chloride (CaCl2)-induced abdominal aortic aneurysms (AAA) in Smad3(-/-), Smad3(+/-) and Smad3(+/+) mice. We find that loss of SMAD3 drastically increases wall thickening of the abdominal aorta. Histological analyses show significant vessel wall remodeling with elastic fiber fragmentation. Remarkably, under polarized light, collagen fibers in the hyperplastic adventitia of Smad3(-/-) mice show extensive reorganization accompanied by loosely packed thin and radial collagen fibers. The expressions of matrix metalloproteinases including MMP2, MMP9, and MMP12 and infiltration of macrophage/T cells are drastically enhanced in the vascular wall of Smad3(-/-) mice. We also observe marked increase of NF-κB and ERK1/2 signaling as well as the expression of nuclear Smad2, Smad4 and TGF-β1 in the vessel wall of Smad3(-/-) mice. In addition, we find that SMAD3 expression is reduced in the dedifferentiated medial smooth muscle-like cells of human AAA patients. These findings provide direct in vivo evidence to support the essential roles of SMAD3 in protecting vessel wall integrity and suppressing inflammation in the pathogenesis of AAAs.

Topics: Animals; Aortic Aneurysm, Abdominal; Atrial Remodeling; Calcium Chloride; Collagen; Disease Models, Animal; Elastin; Extracellular Matrix; Gene Expression Regulation; Inflammation; Leukocytes; Matrix Metalloproteinases; Mice; Mice, Knockout; NF-kappa B; Signal Transduction; Smad2 Protein; Smad3 Protein; Transforming Growth Factor beta

Autophagy regulates cellular homeostasis and integrates the cellular pro-survival machinery. We investigated the role of autophagy in the natural history of murine abdominal aortic aneurysms (AAA). ApoE(-/-) mice were implanted with saline- or angiotensin II (Ang-II)-filled miniosmotic pumps then treated with either the autophagy inhibitor chloroquine (CQ; 50 mg·(kg body mass)(-1)·day(-1), by intraperitoneal injection) or saline. Ang-II-elicited aneurysmal expansion of the suprarenal aorta coupled with thrombus formation were apparent 8 weeks later. CQ had no impact on the incidence (50% for Ang-II compared with 46.2% for Ang-II + CQ; P = NS) and categorical distribution of aneurysms. The markedly reduced survival rate observed with Ang-II (57.1% for Ang-II compared with 100% for saline; P < 0.05) was unaffected by CQ (61.5% for Ang-II + CQ; P = NS compared with Ang-II). CQ did not affect the mean maximum suprarenal aortic diameter (1.91 ± 0.19 mm for Ang-II compared with 1.97 ± 0.21 mm for Ang-II + CQ; P = NS). Elastin fragmentation, collagen accumulation, and smooth muscle attrition, which were higher in Ang-II-treated mice, were unaffected by CQ treatment. Long-term CQ administration does not affect the natural history and prognosis of experimental AAA, suggesting that global loss of autophagy is unlikely to be a causal factor in the development of aortic aneurysms. Manipulation of autophagy as a mechanism to reduce AAA may need re-evaluation.

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; Autophagy; Chloroquine; Collagen; Disease Models, Animal; Disease Progression; Elastin; Male; Mice, Inbred C57BL; Mice, Knockout; Time Factors

Abdominal aortic aneurysm (AAA) is characterized by inflammation, loss of smooth muscle cells (SMCs), and degradation of the extracellular matrix in the vessel wall. Innate immune receptors such as Toll-like receptors (TLRs) were recently shown to regulate immunological processes leading to the formation and progression of atherosclerotic plaques as well as to other cardiovascular pathologies. Our aim was to investigate whether blockage of TLR signaling, under the control of TIR domain-containing adaptor protein including IFN-β (TRIF), could inhibit the inflammatory response and AAA development in mice.. In human AAA, an increased TLR3 and TLR4 expression in association with macrophages and T lymphocytes was demonstrated with immunohistochemical analysis. Angiotensin (Ang) II-induced aneurysm formation was significantly reduced by 30% in ApoE(-/-)Trif(-/-) mice compared to ApoE(-/-) mice. Morphologically, AngII-infused ApoE(-/-)Trif(-/-) mice had a more intact cellular and extracellular matrix while ApoE(-/-) mice infused with AngII displayed an increased medial thickness associated with aortic dissection, thrombus formation, and a more disorganized vessel wall. Gene expression analysis of the abdominal aorta revealed a profound decrease of the inflammatory genes CD68 (P < 0.05), CD11b (P < 0.05), and TNF-α (P < 0.05) and the protease gene MMP-12 (P < 0.01) in ApoE(-/-)Trif(-/-) mice compared to ApoE(-/-) mice infused with AngII.. Our results suggest that signaling through TRIF is important for the inflammatory response of AngII-induced AAA and that blockage of the TRIF pathway reduces vascular inflammation and protects against AAA formation.

Topics: Adaptor Proteins, Vesicular Transport; Angiotensin II; Animals; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Aorta; Aortic Aneurysm, Abdominal; Apolipoproteins; Apolipoproteins E; CD3 Complex; Elastin; Gene Expression Regulation; Humans; Inflammation; Mice; Mice, Knockout; Signal Transduction; Toll-Like Receptors

Thrombomodulin (TM), a glycoprotein constitutively expressed in the endothelium, is well known for its anticoagulant and anti-inflammatory properties. Paradoxically, we recently found that monocytic membrane-bound TM (ie, endogenous TM expression in monocytes) triggers lipopolysaccharide- and gram-negative bacteria-induced inflammatory responses. However, the significance of membrane-bound TM in chronic sterile vascular inflammation and the development of abdominal aortic aneurysm (AAA) remains undetermined.. Implicating a potential role for membrane-bound TM in AAA, we found that TM signals were predominantly localized to macrophages and vascular smooth muscle cells in human aneurysm specimens. Characterization of the CaCl2-induced AAA in mice revealed that during aneurysm development, TM expression was mainly localized in infiltrating macrophages and vascular smooth muscle cells. To investigate the function of membrane-bound TM in vivo, transgenic mice with myeloid- (LysMcre/TM(flox/flox)) and vascular smooth muscle cell-specific (SM22-cre(tg)/TM(flox/flox)) TM ablation and their respective wild-type controls (TM(flox/flox) and SM22-cre(tg)/TM(+/+)) were generated. In the mouse CaCl2-induced AAA model, deficiency of myeloid TM, but not vascular smooth muscle cell TM, inhibited macrophage accumulation, attenuated proinflammatory cytokine and matrix metalloproteinase-9 production, and finally mitigated elastin destruction and aortic dilatation. In vitro TM-deficient monocytes/macrophages, versus TM wild-type counterparts, exhibited attenuation of proinflammatory mediator expression, adhesion to endothelial cells, and generation of reactive oxygen species. Consistently, myeloid TM-deficient hyperlipidemic mice (ApoE(-/-)/LysMcre/TM(flox/flox)) were resistant to AAA formation induced by angiotensin II infusion, along with reduced macrophage infiltration, suppressed matrix metalloproteinase activities, and diminished oxidative stress.. Membrane-bound TM in macrophages plays an essential role in the development of AAA by enhancing proinflammatory mediator elaboration, macrophage recruitment, and oxidative stress.

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortitis; Calcium Chloride; Cell Membrane; Cells, Cultured; Chemotaxis; Disease Models, Animal; Elastin; Human Umbilical Vein Endothelial Cells; Humans; Inflammation Mediators; Macrophages, Peritoneal; Matrix Metalloproteinase 9; Mice, Inbred C57BL; Mice, Knockout; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Oxidative Stress; Retrospective Studies; RNA Interference; Signal Transduction; Thrombomodulin; Time Factors; Transfection

Matrix metalloproteinases (MMPs)-mediated extracellular matrix destruction is the major cause of development and progression of abdominal aortic aneurysms. Systemic treatments of MMP inhibitors have shown effectiveness in animal models, but it did not translate to clinical success either because of low doses used or systemic side effects of MMP inhibitors. We propose a targeted nanoparticle (NP)-based delivery of MMP inhibitor at low doses to the abdominal aortic aneurysms site. Such therapy will be an attractive option for preventing expansion of aneurysms in patients without systemic side effects.. Our previous study showed that poly(d,l-lactide) NPs conjugated with an antielastin antibody could be targeted to the site of an aneurysm in a rat model of abdominal aortic aneurysms. In the study reported here, we tested whether such targeted NPs could deliver the MMP inhibitor batimastat (BB-94) to the site of an aneurysm and prevent aneurysmal growth.. Poly(d,l-lactide) NPs were loaded with BB-94 and conjugated with an elastin antibody. Intravenous injections of elastin antibody-conjugated BB-94-loaded NPs targeted the site of aneurysms and delivered BB-94 in a calcium chloride injury-induced abdominal aortic aneurysms in rats. Such targeted delivery inhibited MMP activity, elastin degradation, calcification, and aneurysmal development in the aorta (269% expansion in control versus 40% elastin antibody-conjugated BB-94-loaded NPs) at a low dose of BB-94. The systemic administration of BB-94 alone at the same dose was ineffective in producing MMP inhibition.. Targeted delivery of MMP inhibitors using NPs may be an attractive strategy to inhibit aneurysmal progression.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Calcium Chloride; Chemistry, Pharmaceutical; Disease Models, Animal; Disease Progression; Drug Carriers; Elastin; Immunoconjugates; Macrophages; Male; Matrix Metalloproteinase Inhibitors; Matrix Metalloproteinases; Mice; Nanoparticles; Phenylalanine; Polyesters; Proteolysis; Rats, Sprague-Dawley; RAW 264.7 Cells; Thiophenes; Time Factors; Vascular Calcification

Abdominal aortic aneurysms (AAAs) are associated with oxidative stress and inflammatory response. We investigated the hypothesis that the known antioxidant ascorbic acid, which can also promote elastin and collagen production by smooth muscle cells, would prevent AAA formation in a rat model.. An intraluminal elastase and extraluminal calcium chloride-induced rat AAA model was used, and the animals were divided into three groups: control (group C, n = 18), the aorta wrapped with a saline-impregnated gelatin hydrogel sheet (group G, n = 18), and the aorta wrapped with a gelatin hydrogel sheet incorporating ascorbic acid (group A, n = 18). Wrapping of the sheet was completed at the end of treatment for AAA creation. The aortic dilatation ratio was measured, and aortic tissues were further examined for oxidative stress and oxidative DNA damage using biochemical and histologic techniques.. Aortic dilatation at both 4 and 8 weeks was inhibited in group A (dilatation ratio [%] at 4 weeks: 186.2 ± 21.8 in group C, 152.3 ± 10.2 in group G, 126.8 ± 11.6 in group A; P < .0001; dilatation ratio [%] at 8 weeks: 219.3 ± 37.5 in group C, 194.0 ± 11.6 in group G, 145.7 ± 8.3 in group A; P = .0002). Elastin and collagen content were significantly preserved in group A (elastin, P = .0015; collagen, P < .0001). The messenger RNA expressions of matrix metalloproteinase (MMP)-9, monocyte chemotactic protein-1, interleukin-1β, and tissue necrosis factor-α (P = .0024, P < .0001, P < .0001, and P < .0001, respectively) were downregulated in group A (P = .0024), whereas tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 were both upregulated in group A (TIMP-1, P = .0014; TIMP-2, P < .0001). Gelatin zymography showed activities of pro-MMP-2, MMP-2, and MMP-9 were significantly suppressed in group C (P < .0001 for each). Reactive oxygen species expression and 8-hydroxydeoxyguanosine and cluster of differentiation 68 staining were significantly suppressed in group A (reactive oxygen species expression, P < .0001; 8-hydroxydeoxyguanosine-positive cells, P < .0001; cluster of differentiation 68 positive cells, P < .0001).. Controlled release of ascorbic acid using gelatin hydrogel sheet-attenuated AAA formation through antioxidant and anti-inflammatory effect, regulation of MMP-2, TIMP-1, and TIMP-2, and preserving elastin and collagen in this animal model.

Topics: Animals; Antioxidants; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Ascorbic Acid; Calcium Chloride; Chemistry, Pharmaceutical; Chemokine CCL2; Collagen; Delayed-Action Preparations; Dilatation, Pathologic; Disease Models, Animal; DNA Damage; Drug Carriers; Elastin; Gelatin; Gene Expression Regulation; Hydrogels; Inflammation Mediators; Interleukin-1beta; Male; Matrix Metalloproteinase 9; Oxidative Stress; Pancreatic Elastase; Rats; Rats, Sprague-Dawley; RNA, Messenger; Time Factors; Tissue Inhibitor of Metalloproteinase-1; Tissue Inhibitor of Metalloproteinase-2; Tumor Necrosis Factor-alpha

The purpose of this study was to further elucidate the role of the vascular smooth muscle cells (SMCs) in abdominal aortic aneurysm (AAA) disease. We hypothesized that that AAA SMCs are unique and actively participate in the process of degrading the aortic matrix.. Whole-genome expression profiles of SMCs from AAAs, nondilated abdominal aorta (NAA), and carotid endarterectomy (CEA) were compared. We quantified elastolytic activity by culturing SMCs in [(3)H]elastin-coated plates and measuring solubilized tritium in the media after 7 days. Matrix metalloproteinase (MMP)-2 and MMP-9 production was assessed using real-time polymerase chain reaction, zymography, and Western blotting.. Each SMC type exhibited a unique gene expression pattern. AAA SMCs had greater elastolytic activity than NAA-SMCs (+68%; P < .001) and CEA-SMCs (+45%; P < .001). Zymography showed an increase of active MMP-2 (62 kD) in media from AAA SMCs. AAA SMCs demonstrated twofold greater expression of MMP-2 messenger (m)RNA (P < .05) and 7.3-fold greater MMP-9 expression (P < .01) than NAA-SMCs. Culture with U937 monocytes caused a synergistic increase of elastolysis by AAA SMCs (41%; P < .001) but not NAA-SMCs or CEA-SMCs (P = .99). Coculture with U937 caused a large increase in MMP-9 mRNA in AAA-SMCs and NAA-SMCs (P < .001). MMP-2 mRNA expression was not affected. Western blots of culture media showed a fourfold increase of MMP-9 (92 kD) protein only in AAA-SMCs/U937 but not in NAA-SMCs/U937 (P < .001) and a large increase in active-MMP2 (62 kD), which was less apparent in NAA-SMCs/U937 media (P < .01).. AAA-SMCs have a unique gene expression profile and a proelastolytic phenotype that is augmented by macrophages. This may occur by a failure of post-transcriptional control of MMP-9 synthesis.

Topics: Aortic Aneurysm, Abdominal; Blotting, Western; Cells, Cultured; Elastin; Flow Cytometry; Gene Expression; Humans; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Muscle, Smooth, Vascular; Real-Time Polymerase Chain Reaction; RNA, Messenger

Thrombus ages, defined as four relative age phases, are related to different compositions of the intraluminal thrombus (ILT) in the abdominal aortic aneurysm (AAA) (Tong et al., 2011b). Experimental studies indicate a correlation between the relative thrombus age and the strength of the thrombus-covered wall.. On 32 AAA samples we performed peeling tests with the aim to dissect the material (i) through the ILT thickness, (ii) within the individual ILT layers and (iii) within the aneurysm wall underneath the thrombus by using two extension rates (1mm/min, 1mm/s). Histological investigations and mass fraction analysis were performed to characterize the dissected morphology, to determine the relative thrombus age, and to quantify dry weight percentages of elastin and collagen in the AAA wall.. A remarkably lower dissection energy was needed to dissect within the individual ILT layers and through the thicknesses of old thrombi. With increasing ILT age the dissection energy of the underlying intima-media composite continuously decreased and the anisotropic dissection properties for that composite vanished. The quantified dissection properties were rate dependent for both tissue types (ILT and wall). Histology showed that single fibrin fibers or smaller protein clots within the ILT generate smooth dissected surfaces during the peeling. There was a notable decrease in mass fraction of elastin within the thrombus-covered intima-media composite with ILT age, whereas no significant change was found for that of collagen.. These findings suggest that intraluminal thrombus aging leads to a higher propensity of dissection for the ILT and the intima-media composite of the aneurysmal wall.

Topics: Aged; Aged, 80 and over; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Dissection; Collagen; Elastin; Endothelium, Vascular; Fibrin; Humans; Middle Aged; Pressure; Thrombosis

Abdominal aortic aneurysms (AAA) are progressive dilatations of infra-renal aorta causing structural weakening rendering the aorta prone to rupture. AAA can be potentially stabilized by inhibiting inflammatory enzymes such as matrix metalloproteinases (MMP); however, active regression of AAA is not possible without new elastic fiber regeneration. Here we report the elastogenic benefit of direct delivery of polyphenols such as pentagalloyl glucose (PGG), epigallocatechin gallate (EGCG), and catechin, to smooth muscle cells obtained either from healthy or from aneurysmal rat aorta. Addition of 10 μg/ml PGG and ECGC induce elastin synthesis, organization, and crosslinking while catechin does not. Our results indicate that polyphenols bind to monomeric tropoelastin and enhance coacervation, aid in crosslinking of elastin by increasing lysyl oxidase (LOX) synthesis, and by blocking MMP-2 activity. Thus, polyphenol treatments leads to increased mature elastin fibers synthesis without increasing the production of intracellular tropoelastin.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Catechin; Cells, Cultured; Elastic Tissue; Elastin; Fibrillins; Hydrolyzable Tannins; Kinetics; Male; Matrix Metalloproteinase 2; Microfilament Proteins; Microscopy, Electron, Transmission; Microscopy, Fluorescence; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Polyphenols; Protein-Lysine 6-Oxidase; Rats; Rats, Sprague-Dawley; Regeneration; Tropoelastin

Understanding variations in size and pattern of development of angiotensin II (Ang II)-induced abdominal aortic aneurysms (AAA) may inform translational research strategies. Thus, we sought insight into the temporal evolution of AAA in apolipoprotein (apo)E(-/-) mice.. A cohort of mice underwent a 4-week pump-mediated infusion of saline (n = 23) or 1500 ng/kg/min of Ang II (n = 85) and AAA development was tracked via in vivo ultrasound imaging. We adjusted for hemodynamic covariates in the regression models for AAA occurrence in relation to time.. The overall effect of time was statistically significant (p<0.001). Compared to day 7 of AngII infusion, there was no decrease in the log odds of AAA occurrence by day 14 (-0.234, p = 0.65), but compared to day 21 and 28, the log odds decreased by 9.07 (p<0.001) and 2.35 (p = 0.04), respectively. Hemodynamic parameters were not predictive of change in aortic diameter (Δ) (SBP, p = 0.66; DBP, p = 0.66). Mean total cholesterol (TC) was higher among mice with large versus small AAA (601 vs. 422 mg/ml, p<0.0001), and the difference was due to LDL. AngII exposure was associated with 0.43 mm (95% CI, 0.27 to 0.61, p<0.0001) increase in aortic diameter; and a 100 mg/dl increase in mean final cholesterol level was associated with a 12% (95% CI, 5.68 to 18.23, p<0.0001) increase in aortic diameter. Baseline cholesterol was not associated with change in aortic diameter (p = 0.86).. These are the first formal estimates of a consistent pattern of Ang II-induced AAA development. The odds of AAA occurrence diminish after the second week of Ang II infusion, and TC is independently associated with AAA size.

Topics: Angiotensin II; Animals; Aortic Aneurysm, Abdominal; Apolipoproteins E; Atherosclerosis; Cholesterol; Elastin; Hypercholesterolemia; Macrophages; Male; Matrix Metalloproteinase 2; Mice; Mice, Inbred C57BL; Muscle, Smooth, Vascular; Time Factors; Ultrasonography

The incidence of abdominal aortic aneurysms (AAAs) has increased during the last decades. However, there is still controversy about the management of medium-sized AAAs. Therefore, novel biomarkers, besides aneurysmal diameter, are needed to assess aortic wall integrity and risk of rupture. Elastin is the key protein for maintaining aortic wall tensile strength and stability. The progressive breakdown of structural proteins, in particular, medial elastin, is responsible for the inability of the aortic wall to withstand intraluminal hemodynamic forces. Here, we evaluate the usefulness of elastin-specific molecular MRI for the in vivo characterization of AAAs.. To induce AAAs, ApoE(-/-) mice were infused with angiotensin-II. An elastin-specific magnetic resonance molecular imaging agent (ESMA) was administered after 1, 2, 3, and 4 weeks of angiotensin-II infusion to assess elastin composition of the aorta (n=8 per group). The high signal provided by ESMA allowed for imaging with high spatial resolution, resulting in an accurate assessment of ruptured elastic laminae and the compensatory expression of elastic fibers. In vivo contrast-to-noise ratios and R1-relaxation rates after ESMA administration were in good agreement with ex vivo histomorphometry (Elastica van Gieson stain) and gadolinium concentrations determined by inductively coupled plasma mass spectroscopy. Electron microscopy confirmed colocalization of ESMA with elastic fibers.. Changes in elastin content could be readily delineated and quantified at different stages of AAAs by elastin-specific molecular magnetic resonance imaging. ESMA-MRI offers potential for the noninvasive detection of the aortic rupture site prior to dilation of the aorta and the subsequent in vivo monitoring of compensatory repair processes during the progression of AAAs.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elasticity; Elastin; Magnetic Resonance Imaging; Male; Mass Spectrometry; Mice; Mice, Inbred C57BL; Microscopy, Electron; Molecular Imaging

Accurately estimating patient-specific rupture risk remains a primary challenge in timing interventions for abdominal aortic aneurysms (AAAs). By re-analyzing published biaxial mechanical testing data from surgically repaired human AAAs, material anisotropy emerged as a potentially important determinant of patient-specific lesion progression. That is, based on a new classification scheme, we discovered that anisotropic aneurysmal specimens correlated with increased patient age at surgery when compared with more isotropic specimens (79.7 vs. 70.9 years, p<0.002), despite no significant difference in maximum diameter. Furthermore, using an idealized axisymmetric, finite-element growth and remodeling model of AAA progression, we found that both the initial axial extent of elastin loss and ongoing damage to elastin in the shoulder region of the AAA directly affected the degree of anisotropy as the lesion evolved, with more extensive insults increasing the anisotropy. This effect appeared to be mediated by alterations in axial loading and subsequent differences in orientation of deposited collagen fibers. While the observed increased age before surgical intervention may suggest a potential benefit of anisotropic remodeling, future biaxial tests coupled with pre-surgical data on expansion rates and detailed theoretical analyses of the biostability of a lesion as a function of anisotropy will be required to verify its clinical relevance to patient-specific rupture risk.

Topics: Aged; Aged, 80 and over; Anisotropy; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Disease Progression; Elastin; Finite Element Analysis; Humans; Middle Aged; Models, Cardiovascular

Abdominal aortic aneurysm (AAA) is a life-threatening disease and its prevalence rate increases with social aging. The degradation of elastic is an important factor in the formation of AAA.. Adipose derived stem cells (ADSCs) and bone marrow mesenchymal stem cells (BMSCs) were isolated from rats, and identified by Oil red O and alizarin red staining after adipogenesis and osteogenesis induction. In addition, ADSCs were also identified by flow cytometry with CD markers. AAA model in rats was established, and smooth muscle cells (SMCs) were isolated from AAA aortic wall and identified by immunohistochemistry. ADSCs or BMSCs were co-cultured with AAA aortic wall for in vitro experiment, and ADSCs were injected into AAA model for in vivo test. Then orcein staining was used for observing the morphology of elastic fiber, Western blot and real-time PCR were used respectively to detect the protein and gene expression of elastin, gelatinases spectrum analysis was used to detect the activity of matrix metalloproteinase-2 (MMP-2) and MMP-9.. Lots of red lipid droplets were visible by Oil red O staining after adipogenesis induction, and black calcium nodules appeared by alizarin red staining after osteogenesis induction. The results of flow cytometry showed that ADSCs expressed CD44 and CD105, but exhibited negligible expression of CD31 and CD45. SMCs exhibited spindle-like morphology and α-actin protein was positive in cytoplasm. After co-cultured with ADSCs or BMSCs, the elastic fiber recovered normal winding shape, both the gene and protein expression of elastin increased, and the activity of MMP-2 decreased. The in vivo result was similar to that of in vitro.. ADSCs promote the expression of elastin in SMCs and contribute to the reconstruction of elastic fiber, which may provide new ideas for treating AAA.

Topics: Adipose Tissue; Animals; Aortic Aneurysm, Abdominal; Coculture Techniques; Elastin; Male; Muscle, Smooth; Rats; Rats, Sprague-Dawley; Stem Cells

The progression of abdominal aortic aneurysm (AAA) involves a sustained influx of proinflammatory macrophages, which exacerbate tissue injury by releasing cytokines, chemokines, and matrix metalloproteinases. Previously, we showed that Notch deficiency reduces the development of AAA in the angiotensin II-induced mouse model by preventing infiltration of macrophages. Here, we examined whether Notch inhibition in this mouse model prevents progression of small AAA and whether these effects are associated with altered macrophage differentiation.. Treatment with pharmacological Notch inhibitor (DAPT [N-(N-[3,5-difluorophenacetyl]-L-alanyl)-S-phenylglycine t-butyl ester]) at day 3 or 8 of angiotensin II infusion arrested the progression of AAA in Apoe(-/-) mice, as demonstrated by a decreased luminal diameter and aortic width. The abdominal aortas of Apoe(-/-) mice treated with DAPT showed decreased expression of matrix metalloproteinases and presence of elastin precursors including tropoelastin and hyaluronic acid. Marginal adventitial thickening observed in the aorta of DAPT-treated Apoe(-/-) mice was not associated with increased macrophage content, as observed in the mice treated with angiotensin II alone. Instead, DAPT-treated abdominal aortas showed increased expression of Cd206-positive M2 macrophages and decreased expression of Il12-positive M1 macrophages. Notch1 deficiency promoted M2 differentiation of macrophages by upregulating transforming growth factor β2 in bone marrow-derived macrophages at basal levels and in response to IL4. Protein expression of transforming growth factor β2 and its downstream effector pSmad2 also increased in DAPT-treated Apoe(-/-) mice, indicating a potential link between Notch and transforming growth factor β2 signaling in the M2 differentiation of macrophages.. Pharmacological inhibitor of Notch signaling prevents the progression of AAA by macrophage differentiation-dependent mechanisms. The study also provides insights for novel therapeutic strategies to prevent the progression of small AAA.

Topics: Aged; Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; Cell Differentiation; Cells, Cultured; Collagen; Dipeptides; Disease Models, Animal; Disease Progression; Elastin; Gene Expression Regulation; Humans; Macrophages; Male; Matrix Metalloproteinases; Mice, Knockout; Middle Aged; Receptor, Notch1; Signal Transduction; Time Factors; Transforming Growth Factor beta2

The pathological characteristics of abdominal aortic aneurysm (AAA) involved the regression of extracellular matrix (ECM) in aortic walls, especially elastic structure in medial layer. As the major structural protein of aorta, elastin contributes to the extensibility and elastic recoil of the vessels. We hypothesized that overexpression of elastin in vessel walls might regenerate the elastic structure of ECM, restore the elastic structure of the aneurysmal wall, and eventually lead to a reduction of aortic diameters (ADs) in an experimental model of AAA.. Tropoelastin (TE) of Sprague Dawley (SD) rat was synthesized by reverse transcription polymerase chain reaction and used to construct adneviral vectors containing elastin precursor protein (AdTE-GFP). Cultured vascular smooth muscle cells (VSMCs) from aortas of male SD rats were transfected with AdTE-GFP, AdGFP, adenoviral vector (AdNull), and phosphate buffered saline (PBS). Immunofluorescence staining was performed to determine the expression of elastin in transfected cells. The expression of elastic fibers in ECM of VSMCs transfected with AdTE-GFP were detected by fluorescence microscopy and transmission electron microscopy (TEM) at 1, 3, and 5 days following gene transfer. The AAA vessel walls were infused with AdTE-GFP or an empty AdNull, or PBS directly into the aneurysmal lumen. ADs of the aneurysms were compared in infused aortas. Formation of new elastic fibers in vivo was assessed by hematoxylin and eosin, and elastic von-Giesson staining. Recombinant elastin-GFP in vivo was identified by immunohistochemical staining.. Elastic fibers were increased both in ECM of VSMC and in vessel walls after gene transfer. Histological studies revealed that the AdTE-GFP-transduced aortas had elastic fiber regeneration in the aneurysmal walls. The AdTE-GFP-transduced aortas showed a decreased AD (23.04% ± 14.49%, P < 0.01) in AAA vessel walls.. Elastic fibers have been successfully overexpressed both in vitro and in a rat model of AAA by a technique of gene transfer. The overexpression of elastic fibers within the aneurysmal tissue appeared to reverse the aneurysm dilatation in this model.

Topics: Animals; Aortic Aneurysm, Abdominal; Elastic Tissue; Elastin; Fluorescent Antibody Technique; Male; Muscle, Smooth, Vascular; Rats; Rats, Sprague-Dawley; Tropoelastin

Elevated plasma aldosterone concentrations in patients have been linked to a spectrum of cardiovascular diseases. Mineralocorticoid receptor antagonists provide additional benefits in patients with heart failure. However, whether aldosterone and the mineralocorticoid receptor are involved in aortic aneurysm is unknown.. We report that administration of deoxycorticosterone acetate (DOCA) and salt or aldosterone and salt, but not DOCA or salt alone, to C57BL/6 male mice induced abdominal and thoracic aortic aneurysm formation and rupture in an age-dependent manner. DOCA and salt- or aldosterone and salt-induced aortic aneurysm mimicked human aortic aneurysm with respect to elastin degradation, inflammatory cell infiltration, smooth muscle cell degeneration and apoptosis, and oxidative stress. Aortic aneurysm formation did not correlate with the increase in blood pressure induced by DOCA and salt. Systemic administration of the angiotensin-converting enzyme inhibitor, enalapril, or angiotensin type 1 receptor antagonist, losartan, did not affect DOCA and salt-induced aortic aneurysm. In contrast, the mineralocorticoid receptor antagonists, spironolactone or eplerenone, significantly attenuated DOCA and salt- or aldosterone and salt-induced aortic aneurysm.. The current study describes a novel aortic aneurysm animal model induced by mineralocorticoid receptor agonist and high salt, and reveals a previously unrecognized but potentially significant role of aldosterone in the pathogenesis of aortic aneurysm. These findings imply that mineralocorticoid receptor antagonists may be effective in the treatment of some aortic aneurysms.

Topics: Aldosterone; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Animals; Aorta; Aortic Aneurysm, Abdominal; Aortic Aneurysm, Thoracic; Aortic Rupture; Apoptosis; Blood Pressure; Desoxycorticosterone; Disease Models, Animal; Elastin; Enalapril; Eplerenone; Losartan; Male; Mice; Mice, Inbred C57BL; Mineralocorticoid Receptor Antagonists; Muscle, Smooth, Vascular; Oxidative Stress; Receptors, Mineralocorticoid; Sodium Chloride, Dietary; Spironolactone; Time Factors

Abdominal aortic aneurysms (AAAs) are potentially fatal conditions that are characterized by decreased flexibility of the aortic wall due to proteolytic loss of the structural matrix. This leads to their gradual weakening and ultimate rupture. Drug-based inhibition of proteolytic enzymes may provide a nonsurgical treatment alternative for growing AAAs, although it might at best be sufficient to slow their growth. Regenerative repair of disrupted elastic matrix is required if regression of AAAs to a healthy state is to be achieved. Terminally differentiated adult and diseased vascular cells are poorly capable of affecting such regenerative repair. In this context, stem cells and their smooth muscle cell-like derivatives may represent alternate cell sources for regenerative AAA cell therapies. This article examines the pros and cons of using different autologous stem cell sources for AAA therapy, the requirements they must fulfill to provide therapeutic benefit, and the current progress toward characterizing the cells' ability to synthesize elastin, assemble elastic matrix structures, and influence the regenerative potential of diseased vascular cell types. The article also provides a detailed perspective on the limitations, uncertainties, and challenges that will need to be overcome or circumvented to translate current strategies for stem cell use into clinically viable AAA therapies. These therapies will provide a much needed nonsurgical treatment option for the rapidly growing, high-risk, and vulnerable elderly demographic.

Topics: Aged; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Becaplermin; Elasticity; Elastin; Extracellular Matrix; Humans; Myocytes, Smooth Muscle; Proto-Oncogene Proteins c-sis; Regeneration; Stem Cell Transplantation; Stem Cells; Transforming Growth Factor beta; Transplantation, Autologous

Plasma phospholipid transfer protein (PLTP) increases the circulating levels of proatherogenic lipoproteins, accelerates blood coagulation, and modulates inflammation. The role of PLTP in the development of abdominal aortic aneurysm (AAA) was investigated by using either a combination of mechanical and elastase injury at one site of mouse aorta (elastase model) or continuous infusion of angiotensin II in hyperlipidemic ApoE-knockout mice (Ang II model). With the elastase model, complete PLTP deficiency was associated with a significantly lower incidence and a lesser degree of AAA expansion. With the Ang II model, findings were consistent with those in the elastase model, with a lower severity grade in PLTP-deficient mice, an intermediate phenotype in PLTP-deficient heterozygotes, and a blunted effect of the PLTP-deficient trait when restricted to bone marrow-derived immune cells. The protective effect of whole-body PLTP deficiency in AAA was illustrated further by a lesser degree of adventitia expansion, reduced elastin degradation, fewer recruited macrophages, and less smooth muscle cell depletion in PLTP-deficient than in wild-type mice, as evident from comparative microscopic analysis of aorta sections. Finally, cumulative evidence supports the association of PLTP deficiency with reduced expression and activity levels of matrix metalloproteinases, known to degrade elastin and collagen. We conclude that PLTP can play a significant role in the pathophysiology of AAA.

Topics: Angiotensin II; Animals; Aorta; Aortic Aneurysm, Abdominal; Apolipoproteins E; CD4-Positive T-Lymphocytes; Cytokines; Elastin; Inflammation; Liver; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Pancreatic Elastase; Phospholipid Transfer Proteins

The purpose of this study was to introduce a novel, simple and effective technique for creating a reliable rabbit model of abdominal aortic aneurysm (AAA) via a combination of periaortic calcium chloride (CaCl2) and elastase incubation.. Forty-eight New Zealand white rabbits were divided into four groups. The AAA model was developed via a 20-minute periaortic incubation of CaCl2 (0.5 mol/L) and elastase (1 Unit/µL) in a 1.5-cm aortic segment (Group CE). A single incubation of CaCl2 (Group C) or elastase (Group E) and a sham operation group (Sham Group) were used for the controls. Diameter was measured by serial digital subtraction angiography imaging on days 5, 15 and 30. Animals were sacrificed on day 5 and day 30 for histopathological and immunohistochemical studies.. All animals in Group CE developed aneurysm, with an average dilation ratio of 65.3% ± 8.9% on day 5, 86.5% ± 28.7% on day 15 and 203.6% ± 39.1% on day 30. No aneurysm was found in Group C, and only one aneurysm was seen on day 5 in Group E. Group CE exhibited less intima-media thickness, endothelial recovery, elastin and smooth muscle cell (SMC) content, but stronger expression of matrix metalloproteinase-2, matrix metalloproteinase-9 and RAM11 compared to the controls.. The novel rabbit model of AAA created by using a combination of periaortic CaCl2 and elastase incubation is simple and effective to perform and is valuable for elucidating AAA mechanisms and therapeutic interventions in experimental studies.

Topics: Angiography, Digital Subtraction; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Calcium Chloride; Carotid Intima-Media Thickness; Disease Models, Animal; Elastin; Humans; Intubation; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Pancreatic Elastase; Rabbits

Abdominal aortic aneurysm (AAA) is a life-threatening disease affecting almost 10% of the population over the age of 65. Nitrogen-containing bisphosphonates (N-BPs) have been shown to exert anti-atherogenic and anti-angiogenic effects, but the potential effects of N-BPs on AAA remain unclear. Here, we tested whether a potent N-BP, zoledronate, can attenuate the formation of Angiotensin II (Ang II)-induced AAA in hyperlipidaemic mice.. Low-density lipoprotein receptor(-/-) (LDLR(-/-)) mice infused for 28 days with Ang II were treated with placebo and 100 μg/kg/day zoledronate. Continuous Ang II infusion in LDLR(-/-) mice exhibited a 59% incidence of AAA formation, and treatment with zoledronate decreased AAA formation (21%). Compared with the saline group, administration of zoledronate in Ang II-infused LDLR(-/-) mice attenuated the expansion of the suprarenal aorta (maximal aortic diameter), reduced elastin degradation in the media layer of the aorta, and significantly diminished vascular inflammation by reduction in vascular cell adhesion molecule expression and macrophage accumulation. Treatment with zoledronate decreased matrix metalloproteinase-2 (MMP-2) in aortic tissues. Zoledronate-treated mice had significant down-regulation of JNK, NF-κB, and reduced Ang II-induced Rho/ROCK activation. Zoledronate reduced monocytes adherence to human aortic endothelial cells in vitro.. Zoledronate-attenuated Ang II induced AAA formation by suppression of MMP-2 activity and suppressed vascular inflammation and Ang II-induced Rho/ROCK activities.

Topics: Angiotensin II; Animals; Anti-Inflammatory Agents; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Cell Adhesion; Cell Line; Coculture Techniques; Dilatation, Pathologic; Diphosphonates; Disease Models, Animal; Dose-Response Relationship, Drug; Elastin; Endothelial Cells; Enzyme Activation; Humans; Imidazoles; JNK Mitogen-Activated Protein Kinases; Macrophages; Male; Matrix Metalloproteinase 2; Mice; Mice, Inbred C57BL; Mice, Knockout; Monocytes; NF-kappa B; Phosphorylation; Receptors, LDL; rho GTP-Binding Proteins; rho-Associated Kinases; rhoA GTP-Binding Protein; Signal Transduction; Vascular Cell Adhesion Molecule-1; Zoledronic Acid

Abdominal aortic aneurysm (AAA) is a serious disease due to its covert nature, relatively high prevalence and fatal prognosis in the case of rupture. To obtain new insights into AAA pathogenesis, we examined the relationships between histopathology, multiplex in vitro immunoassay data, diameter and symptomatology.. In a prospective, non-randomised study, we evaluated samples from 6 normal infrarenal aortae and 65 AAA patients (65 walls, 55 thrombi). The AAA patients were either asymptomatic (n = 44), symptomatic (n = 7) or with ruptured AAA (n = 14). The AAA diameter was classified as small (<5 cm, n = 18), medium (5-7 cm, n = 26) and large (>7 cm, n = 21). We quantified the histopathology of the AAA wall and the adjacent thrombus. We assessed the expression of proteins in the same samples.. Asymptomatic AAAs had walls with more abundant inflammatory infiltrates, lower amounts of PAI-1, a higher number of tPA-positive elements, a tendency towards decreased collagen content, whereas the adjacent thrombi had a greater concentration of VCAM-1 and MMP-2 when compared with symptomatic AAAs. Compared with the aneurysmatic aorta, the normal aorta contained less collagen and more elastin, actin, desmin and PAI-1-positive elements; in addition, it was more vascular. Medium-sized AAAs were the most actin and vimentin rich, and large AAAs were the most vascular.. Our results show that asymptomatic AAA walls often have more potentially deleterious histopathological alterations than symptomatic AAA walls. This result indicates that a progression from an asymptomatic AAA to rupture can be expected and screening patients who are at risk of rupture could be beneficial.

Topics: Actins; Adult; Aged; Aged, 80 and over; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Rupture; Asymptomatic Diseases; Collagen; Desmin; Disease Progression; Elastin; Extracellular Matrix; Female; Histocytochemistry; Humans; Male; Matrix Metalloproteinase 2; Middle Aged; Plasminogen Activator Inhibitor 1; Prospective Studies; Thrombosis; Vascular Cell Adhesion Molecule-1

An association of intraluminal thrombus (ILT) with abdominal aortic aneurysm (AAA) growth has been suggested. Previous in vitro experiments have demonstrated that aneurysm-associated thrombus may secrete proteolytic enzymes and may develop local hypoxia that might lead to the formation of tissue-damaging reactive oxygen species. In this study, we assessed the hypothesis that ventral ILT thickness is associated with markers of proteolysis and with lipid oxidation in the underlying AAA vessel wall.. Ventral AAA tissue was collected from asymptomatic patients at the site of maximal diameter during open aneurysm repair. Segments were divided, one part for biochemical measurements and one for histologic analyses. We measured total cathepsin B, cathepsin S levels, and matrix metalloproteinase (MMP)-2 and MMP-9 activity. Myeloperoxidase and thiobarbituric acid reactive substances were determined as measures of lipid oxidation. Histologic segments were analyzed semiquantitatively for the presence of collagen, elastin, vascular smooth muscle cells (VSMCs), and inflammatory cells. Preoperative computed tomography angiography scans of 83 consecutive patients were analyzed. A three-dimensional reconstruction was obtained, and a center lumen line of the aorta was constructed. Ventral ILT thickness was measured in the anteroposterior direction at the level of maximal aneurysm diameter on the orthogonal slices.. Ventral ILT thickness was positively correlated with aortic diameter (r=0.25; P=.02) and with MMP-2 levels (r=0.27; P=.02). No biochemical correlations were observed with MMP-9 activity or cathepsin B and S expression. No correlation between ventral ILT thickness and myeloperoxidase or thiobarbituric acid reactive substances was observed. Ventral ILT thickness was negatively correlated with VSMCs (no staining, 18.5 [interquartile range, 12.0-25.5] mm; minor, 17.6 [10.7-22.1] mm; moderate, 14.5 [4.6-21.7] mm; and heavy, 8.0 [0.0-12.3] mm, respectively; P=.01) and the amount of elastin (no staining, 18.6 [12.2-30.0] mm; minor, 16.5 [9.0-22.1] mm; moderate, 11.7 [2.5-15.3] mm; and heavy 7.7 [0.0-7.7] mm, respectively; P=.01) in the medial aortic layer.. ILT thickness appeared to be associated with VSMCs apoptosis and elastin degradation and was positively associated with MMP-2 concentrations in the underlying wall. This suggests that ILT thickness affects AAA wall stability and might contribute to AAA growth and rupture. ILT thickness was not correlated with markers of lipid oxidation.

Topics: Aged; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Rupture; Aortography; Apoptosis; Biopsy; Cathepsin B; Cathepsins; Collagen; Elastin; Female; Humans; Inflammation; Linear Models; Lipid Peroxidation; Logistic Models; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Multivariate Analysis; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Observer Variation; Peroxidase; Predictive Value of Tests; Reproducibility of Results; Thiobarbituric Acid Reactive Substances; Thrombosis; Tomography, X-Ray Computed

To modify the method for creating an abdominal aortic aneurysm in rabbits, and to study its performance.. A total of 24 New Zealand white rabbits were induced topically with 10 μl of porcine elastase (0, 0.1, 5 and 10 units μl(-1)) to define the optimal concentration (groups A-D). Twelve aneurysms were induced with 10 units μl(-1) of 10 μl elastase to serve as a follow-up group (group E) to serve as a follow-up. A 1.5-cm aortic segment was isolated and induced with elastase solution for 30 min.. All animals in groups D and E developed AAA by day 5. Aneurysms in Group E were stable over 100 days. Partial destruction to disappearance of elastic lamellae and smooth muscle cells (SMCs) was seen in elastase-treated animals by day 5. Regenerated elastin and proliferated SMCs were present in group E. Matrix metalloproteinases 2 and 9 and RAM11 showed strong expression in group D, but expression decreased in group E after day 15.. The rabbit AAA model induced via topical application of porcine elastase at 10 units μl(-1) for 30 min appears easy and simple, with shorter induction and more rapid aortic dilation. The model is stable over 100 days and is useful to study the formation and progress of AAAs.

Topics: Administration, Topical; Angiography, Digital Subtraction; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortography; Biomarkers; Cell Proliferation; Dilatation, Pathologic; Disease Models, Animal; Disease Progression; Elastic Tissue; Elastin; Immunohistochemistry; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Muscle, Smooth, Vascular; Pancreatic Elastase; Rabbits; Swine; Time Factors

Abdominal aortic aneurysms (AAAs) are common, but their exact pathogenesis remains unknown and no specific medical therapies are available. We sought to evaluate interleukin-1β (IL-1β) and interleukin-1 receptor (IL-1R) in an experimental AAA model to identify novel therapeutic targets for AAA treatment.. IL-1β mRNA and protein levels were significantly elevated in abdominal aortas of 8- to 12-week-old male C57Bl/6 mice after elastase aortic perfusion (wild-type [WT]) compared with saline perfusion. Mice with genetic deletion of IL-1β (IL-1β knockout [KO]) or IL-1R (IL-1R KO) that underwent elastase perfusion demonstrated significant protection against AAA formation, with maximal aortic dilations of 38.0±5.5% for IL-1β KO and 52.5±4.6% for IL-1R KO, compared with 89.4±4.0% for WT mice (P<0.005). Correspondingly, IL-1β KO and IL-1R KO aortas had reduced macrophage and neutrophil staining with greater elastin preservation compared with WT. In WT mice pretreated with escalating doses of the IL-1R antagonist anakinra, there was a dose-dependent decrease in maximal aortic dilation (R=-0.676; P<0.0005). Increasing anakinra doses correlated with decreasing macrophage staining and elastin fragmentation. Lastly, WT mice treated with anakinra 3 or 7 days after AAA initiation with elastase demonstrated significant protection against AAA progression and had decreased aortic dilation compared with control mice.. IL-1β is critical for AAA initiation and progression, and IL-1β neutralization through genetic deletion or receptor antagonism attenuates experimental AAA formation. Disrupting IL-1β signaling offers a novel pathway for AAA treatment.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Dilatation, Pathologic; Disease Models, Animal; Dose-Response Relationship, Drug; Elastin; Gene Expression Regulation; Humans; Interleukin 1 Receptor Antagonist Protein; Interleukin-1beta; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Neutrophils; Pancreatic Elastase; Receptors, Interleukin-1; RNA, Messenger; Signal Transduction; Time Factors

The main purpose of the present study is the investigation of gender differences in the biomechanical properties, thrombus age, mass fraction and key clinical factors of abdominal aortic aneurysms (AAAs).. A total of 90 AAA samples (78 males and 12 females) were harvested from open surgical aneurysm repairs. Biaxial extension and peeling tests were performed to characterise the biaxial mechanical responses and to determine dissection properties of both the intraluminal thrombi (ILTs) and the thrombus-covered walls. Relative thrombus age was determined by characterising the ILT histological microstructure. Mass fraction analyses quantified dry weight percentages of elastin and collagen within the AAA walls. Moreover, we statistically compared clinical factors between male and female.. The luminal layers of the female thrombi and the female AAA walls showed a significantly lower tissue stiffness (modulus) in the longitudinal direction when compared to males. Gender differences were also shown in the dissection properties of the intima-media composite within the AAA walls, in which a statistically significantly lower energy to propagate a dissection was quantified for females than for males. Moreover, 82% of female thrombi were relatively older (ILT age phases III and IV), twice that of male thrombi (43%). A pronounced lower elastin content was identified for the intima-media composites of male AAA walls, whereas female AAA walls had significantly lower dry weight percentages of collagen. Regarding clinical factors, nicotine pack years, serum creatinine and AAA expansion rate were found to be much higher for male patients.. These findings may help to explain higher risks for AAA growth in males and the ruptures of smaller-sized AAAs in females.

Topics: Aged; Aged, 80 and over; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Dissection; Aortic Rupture; Biomechanical Phenomena; Chi-Square Distribution; Collagen; Disease Progression; Elastic Modulus; Elastin; Female; Humans; Male; Middle Aged; Risk Factors; Sex Factors; Thrombosis; Time Factors; Vascular Stiffness

Cathepsin K (CatK) is one of the most potent mammalian elastases. We have previously shown increased expression of CatK in human abdominal aortic aneurysm (AAA) lesions. Whether this protease participates directly in AAA formation, however, remains unknown.. Mouse experimental AAA was induced with aortic perfusion of a porcine pancreatic elastase. Using this experimental model, we demonstrated that absence of CatK prevented AAA formation in mice 14 days postperfusion. CatK deficiency significantly reduced lesion CD4(+) T-cell content, total lesion and medial cell proliferation and apoptosis, medial smooth muscle cell (SMC) loss, elastinolytic CatL and CatS expression, and elastin fragmentation, but it did not affect AAA lesion Mac-3(+) macrophage accumulation or CD31(+) microvessel numbers. In vitro studies revealed that CatK contributed importantly to CD4(+) T-cell proliferation, SMC apoptosis, and other cysteinyl cathepsin and matrix metalloproteinase expression and activities in SMCs and endothelial cells but played negligible roles in microvessel growth and monocyte migration. AAA lesions from CatK-deficient mice showed reduced elastinolytic cathepsin activities compared with those from wild-type control mice.. This study demonstrates that CatK plays an essential role in AAA formation by promoting T-cell proliferation, vascular SMC apoptosis, and elastin degradation and by affecting vascular cell protease expression and activities.

Topics: Animals; Aortic Aneurysm, Abdominal; Apoptosis; Cathepsin K; CD4-Positive T-Lymphocytes; Cell Proliferation; Disease Models, Animal; Elastin; Humans; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocytes, Smooth Muscle; Neovascularization, Physiologic; Pancreatic Elastase

Group X secretory PLA(2) (sPLA(2)-X) is expressed in neutrophils and plays a role in the pathogenesis of neutrophil-mediated tissue inflammation and injury. This study tested the hypothesis that sPLA(2)-X in neutrophils may contribute to the pathogenesis of abdominal aortic aneurysms (AAA) using sPLA(2)-X(-/-) mice. AAA was created by application of CaCl(2) to external surface of aorta. As a result, the aortas of sPLA(2)-X(-/-) mice had smaller diameters (percent increase from baseline; 24.8 ± 3.5% vs. 49.9 ± 9.1%, respectively; P < 0.01), a reduced grade of elastin degradation, and lower activities of elastase and gelatinase (26% and 19% lower, respectively) after CaCl(2) treatment compared with sPLA(2)-X(+/+) mice. In sPLA(2)-X(+/+) mice, immunofluorescence microscopic images showed that the immunoreactivity of sPLA(2)-X was detected only in neutrophils within aortic walls 3 days, 1, 2, and 6 wk after CaCl(2) treatment, whereas the immunoreactivity was not detected in macrophages or mast cells in aortic walls. sPLA(2)-X immunoreactivity also was colocalized in cells expressing matrix metalloproteinase (MMP)-9. Neutrophils isolated from sPLA(2)-X(-/-) mice had lower activities of elastase, gelatinase, and MMP-9 in response to stimuli compared with sPLA(2)-X(+/+) mice. The attenuated release of elastase and gelatinase from sPLA(2)-X(-/-) neutrophils was reversed by exogenous addition of mouse sPLA(2)-X protein. The adoptive transfer of sPLA(2)-X(+/+) neutrophils days 0 and 3 after CaCl(2) treatment reversed aortic diameters and elastin degradation grades in the lethally irradiated sPLA(2)-X(+/+) mice reconstituted with sPLA(2)-X(-/-) bone marrow to an extent similar to that seen in sPLA(2)-X(+/+) mice. In conclusion, sPLA(2)-X in neutrophils plays a pathogenic role in AAA in a mice model.

Topics: Adoptive Transfer; Animals; Aorta; Aortic Aneurysm, Abdominal; Bone Marrow Transplantation; Calcium Chloride; Disease Models, Animal; Elastin; Gelatinases; Group X Phospholipases A2; Male; Matrix Metalloproteinase 9; Mice; Mice, Inbred C57BL; Mice, Knockout; Microscopy, Fluorescence; Neutrophils; Pancreatic Elastase; Time Factors

MicroRNAs (miRs) regulate gene expression at the posttranscriptional level and play crucial roles in vascular integrity. As such, they may have a role in modifying abdominal aortic aneurysm (AAA) expansion, the pathophysiological mechanisms of which remain incompletely explored. Here, we investigate the role of miRs in 2 murine models of experimental AAA: the porcine pancreatic elastase (PPE) infusion model in C57BL/6 mice and the AngII infusion model in Apoe-/- mice. AAA development was accompanied by decreased aortic expression of miR-29b, along with increased expression of known miR-29b targets, Col1a1, Col3a1, Col5a1, and Eln, in both models. In vivo administration of locked nucleic acid anti-miR-29b greatly increased collagen expression, leading to an early fibrotic response in the abdominal aortic wall and resulting in a significant reduction in AAA progression over time in both models. In contrast, overexpression of miR-29b using a lentiviral vector led to augmented AAA expansion and significant increase of aortic rupture rate. Cell culture studies identified aortic fibroblasts as the likely vascular cell type mediating the profibrotic effects of miR-29b modulation. A similar pattern of reduced miR-29b expression and increased target gene expression was observed in human AAA tissue samples compared with that in organ donor controls. These data suggest that therapeutic manipulation of miR-29b and its target genes holds promise for limiting AAA disease progression and protecting from rupture.

Topics: Adolescent; Aged; Aneurysm, Ruptured; Angiotensin II; Animals; Aortic Aneurysm, Abdominal; Apolipoproteins E; Collagen; Disease Models, Animal; Disease Progression; Elastin; Gene Expression; Humans; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; MicroRNAs; Middle Aged; Pancreatic Elastase; Protein Isoforms; Swine; Young Adult

An ideal pharmaceutical treatment for abdominal aortic aneurysm (AAA) is to prevent aneurysm formation and development (further dilatation of pre-existing aneurysm). Recent studies have reported that oxidative stress with reactive oxygen species (ROS) is crucial in aneurysm formation. We hypothesized that edaravone, a free-radical scavenger, would attenuate vascular oxidative stress and inhibit AAA formation and development.. An AAA model induced with intraluminal elastase and extraluminal calcium chloride was created in 42 rats. Thirty-six rats were divided three groups: a low-dose (group LD; 1 mg/kg/d), high-dose (group HD; 5 mg/kg/d), and control (group C, saline). Edaravone or saline was intraperitoneally injected twice daily, starting 30 minutes before aneurysm preparation. The remaining six rats (group DA) received a delayed edaravone injection (5 mg/kg/d) intraperitoneally, starting 7 days after aneurysm preparation to 28 days. AAA dilatation ratio was calculated. Pathologic examination was performed. ROS expression was semi-quantified by dihydroethidium staining and the oxidative product of DNA induced by ROS, 8-hydroxydeoxyguanosine (8-OHdG), by immunohistochemical staining.. At day 7, ROS expression and 8-OHdG-positive cells in aneurysm walls were decreased by edaravone treatment (ROS expression: 3.0 ± 0.5 in group LD, 1.7 ± 0.3 in group HD, and 4.8 ± 0.7 in group C; 8-OHdG-positive cells: 106.2 ± 7.8 cells in group LD, 64.5 ± 7.7 cells in group HD, and 136.6 ± 7.4 cells in group C; P < .0001), compared with group C. Edaravone treatment significantly reduced messenger RNA expressions of cytokines and matrix metalloproteinases (MMPs) in aneurysm walls (MMP-2: 1.1 ± 0.5 in group LD, 0.6 ± 0.1 in group HD, and 2.3 ± 0.4 in group C; P < .001; MMP-9: 1.2 ± 0.1 in group LD, 0.2 ± 0.6 in group HD, and 2.4 ± 0.2 in group C; P < .001). At day 28, aortic walls in groups LD and HD were less dilated, with increased wall thickness and elastin content than those in group C (dilatation ratio: 204.7% ± 16.0% in group C, 156.5% ± 6.6% in group LD, 136.7% ± 2.0% in group HD; P < .0001). Delayed edaravone administration significantly prevented further aneurysm dilatation, with increased elastin content (155.2% ± 2.9% at day 7, 153.1% ± 11.6% at day 28; not significant).. Edaravone inhibition of ROS can prevent aneurysm formation and expansion in the rat AAA model. Free-radical scavenger edaravone might be an effective pharmaceutical agent for AAA in clinical practice.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Antipyrine; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apoptosis; Biomarkers; Calcium Chloride; Deoxyguanosine; Dilatation, Pathologic; Disease Models, Animal; Disease Progression; Drug Administration Schedule; Edaravone; Elastin; Free Radical Scavengers; Gene Expression Regulation; Immunohistochemistry; Injections, Intraperitoneal; Interleukin-1beta; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Oxidative Stress; Pancreatic Elastase; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Time Factors; Tumor Necrosis Factor-alpha

Mast cells participate importantly in abdominal aortic aneurysms (AAAs) by releasing inflammatory cytokines to promote vascular cell protease expression and arterial wall remodelling. Mast cells accumulate in AAA lesions during disease progression, but the exact chemokines by which mast cells migrate to the site of vascular inflammation remain unknown. This study tested the hypothesis that mast cells use chemokine (C-C motif) receptor 2 (CCR2) for their accumulation in experimental mouse AAA lesions.. We generated mast cell and apolipoprotein E double-deficient (Apoe(-/-)Kit(W-sh/W-sh)) mice and found that they were protected from angiotensin II (Ang II) chronic infusion-induced AAAs compared with Apoe(-/-) littermates. Using bone-marrow derived mast cells (BMMC) from Apoe(-/-) mice and CCR2 double-deficient (Apoe(-/-)Ccr2(-/-)) mice, we demonstrated that Apoe(-/-)Kit(W-sh/W-sh) mice receiving BMMC from Apoe(-/-)Ccr2(-/-) mice, but not those from Apoe(-/-) mice, remained protected from AAA formation. Adoptive transfer of BMMC from Apoe(-/-) mice into Apoe(-/-)Kit(W-sh/W-sh) mice also increased lesion content of macrophages, T cells, and MHC class II-positive cells; there was also increased apoptosis, angiogenesis, cell proliferation, elastin fragmentation, and medial smooth muscle cell loss. In contrast, adoptive transfer of BMMC from Apoe(-/-)Ccr2(-/-) mice into Apoe(-/-)Kit(W-sh/W-sh) mice did not affect these variables.. The increased AAA formation and associated lesion characteristics in Apoe(-/-)Kit(W-sh/W-sh) mice after receiving BMMC from Apoe(-/-) mice, but not from Apoe(-/-)Ccr2(-/-) mice, suggests that mast cells use CCR2 as the chemokine receptor for their recruitment in Ang II-induced mouse AAA lesions.

Topics: Adoptive Transfer; Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; Apoptosis; Cell Proliferation; Cells, Cultured; Chemotaxis; Disease Models, Animal; Elastin; Male; Mast Cells; Mice; Mice, Inbred C57BL; Mice, Knockout; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Neovascularization, Pathologic; Proto-Oncogene Proteins c-kit; Receptors, CCR2

Abdominal aortic aneurysm (AAA) is characterized by extensive aortic wall matrix degradation that contributes to the remodelling and eventual rupture of the arterial wall. Elastinolytic cathepsin S (Cat S) is highly expressed in human aneurysmal lesions, but whether it contributes to the pathogenesis of AAA remains unknown.. AAAs were induced in apolipoprotein E (ApoE) and Cat S compound mutant (Apoe(-/-)Ctss(-/-)) mice and in ApoE-deficient Cat S wild-type littermates (Apoe(-/-)Ctss(+/+)) by chronic angiotensin II infusion, and AAA lesions were analysed after 28 days. We found that Cat S expression increased significantly in mouse AAA lesions. The AAA incidence in Apoe(-/-)Ctss(-/-) mice was much lower than that in Apoe(-/-)Ctss(+/+) mice (10 vs. 80%). Cat S deficiency significantly reduced external and luminal abdominal aortic diameters, medial elastin fragmentation, and adventitia collagen content. Cat S deficiency reduced aortic lesion expression and the activity of matrix metalloproteinase (MMP)-2, MMP-9, and Cat K, but not the activity of other major cathepsins, such as Cat B and Cat L. Absence of Cat S significantly reduced AAA lesion media smooth muscle cell (SMC) apoptosis, lesion adventitia microvessel content, and inflammatory cell accumulation and proliferation. In vitro studies proved that Cat S helps promote SMC apoptosis, angiogenesis, monocyte and T-cell transmigration, and T-cell proliferation--all of which are essential to AAA pathogenesis.. These data provide direct evidence that Cat S plays an important role in AAA formation and suggest that Cat S is a new therapeutic target for human AAA.

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; Apoptosis; Cathepsin K; Cathepsins; CD3 Complex; Cells, Cultured; Collagen; Disease Models, Animal; Elastin; Inflammation; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice; Mice, Inbred C57BL; Mice, Knockout; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Neovascularization, Pathologic; T-Lymphocytes; Time Factors

Apoptosis of smooth muscle cells (SMCs) is a prominent pathological characteristic of abdominal aortic aneurysm (AAA). We have previously shown that SMC apoptosis stimulates proinflammatory signaling in a mouse model of AAA. Here, we test whether protein kinase C-δ (PKCδ), an apoptotic mediator, participates in the pathogenesis of AAA by regulating apoptosis and proinflammatory signals.. Mouse experimental AAA is induced by perivascular administration of CaCl(2). Mice deficient in PKCδ exhibit a profound reduction in aneurysmal expansion, SMC apoptosis, and transmural inflammation as compared with wild-type littermates. Delivery of PKCδ to the aortic wall of PKCδ(-/-) mice restores aneurysm, whereas overexpression of a dominant negative PKCδ mutant in the aorta of wild-type mice attenuates aneurysm. In vitro, PKCδ(-/-) aortic SMCs exhibit significantly impaired monocyte chemoattractant protein-1 production. Ectopic administration of recombinant monocyte chemoattractant protein-1 to the arterial wall of PKCδ(-/-) mice restores inflammatory response and aneurysm development.. PKCδ is an important signaling mediator for SMC apoptosis and inflammation in a mouse model of AAA. By stimulating monocyte chemoattractant protein-1 expression in aortic SMCs, upregulated PKCδ exacerbates the inflammatory process, in turn perpetuating elastin degradation and aneurysmal dilatation. Inhibition of PKCδ may serve as a potential therapeutic strategy for AAA.

Topics: Animals; Aortic Aneurysm, Abdominal; Apoptosis; Calcium Chloride; Cell Movement; Cells, Cultured; Chemokine CCL2; Elastin; In Vitro Techniques; Inflammation; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Models, Animal; Muscle, Smooth, Vascular; Protein Kinase C-delta; Signal Transduction; Up-Regulation

Inhibiting the growth of small abdominal aortic aneurysms (AAAs) is a clinically valuable goal and fills an important therapeutic void. Based on studies in animals and humans, inhibition of the activity of elastolytic matrix metalloproteinases (MMPs) has the potential to slow AAA expansion and limit morbidity and the need for surgery. Previous attempts to make use of the synthetic MMP inhibitors in the treatment of chronic conditions have been limited by intolerable side effects. The limited-spectrum synthetic MMP inhibitor, XL784, was well tolerated and devoid of side-effects associated with other nonspecific MMP inhibitors in phase I studies. We hypothesized that clinically relevant doses of XL784 would be effective at inhibiting aneurysm development in a mouse model.. The 14-day elastase-perfusion model of AAA in mice was used. An initial screening study of XL784 (50 [n = 17], 125 [n = 17], and 250 mg/kg [n = 18]) administered via gavage daily until harvest. Controls received diluent alone (n = 18) or doxycycline in drinking water (n = 19). Aortic diameter was measured pre-perfusion (AD(pre)) and at harvest (AD(har)). A second study used XL784 (250 [n = 9]; 375 [n = 9], and 500 mg/kg [n = 14]) and diluent alone (n = 9) administered via gavage. The percentage dilatation [%ΔAD = [(AD(har) - AD(pre))/AD(pre)] ×100] was calculated and elastin and inflammatory content was scored.. All mice tolerated the treatments similarly. Control mice all developed aneurysms with a mean %ΔAD of 158.5% ± 4.3%. Treatment with all doses of XL784 and doxycycline were effective in inhibiting aortic dilatation. There was a clear dose-response relationship between XL784 and reductions in aortic dilatation at harvest (50 mg/kg 140.4% ± 3.2%; 125 mg/kg 129.3% ± 5.1%; 250 mg/kg 119.2% ± 3.5%; all Ps < .01 compared to control). This continued with the higher doses (375 mg/kg 88.6% ± 4.4%; 500 mg/kg 76.0% ± 3.5%). The highest 2 doses of XL784 tested were more effective than doxycycline (112.2% ± 2.0%, P < .05) in inhibiting maximal dilatation of the aorta after elastase perfusion.

Topics: Administration, Oral; Animals; Anti-Inflammatory Agents, Non-Steroidal; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Rupture; Dilatation, Pathologic; Disease Models, Animal; Disease Progression; Dose-Response Relationship, Drug; Elastin; Half-Life; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase Inhibitors; Mice; Mice, Inbred C57BL; Pancreatic Elastase; Random Allocation; Severity of Illness Index

To quantitatively compare aortic curvature and motion with resulting aneurysm location, direction of expansion, and pathophysiological features in experimental abdominal aortic aneurysms (AAAs).. MRI was performed at 4.7 T with the following parameters: (1) 3D acquisition for vessel geometry and (2) 2D cardiac-gated acquisition to quantify luminal motion. Male 24-week-old mice were imaged before and after AAA formation induced by angiotensin II (AngII)-filled osmotic pump implantation or infusion of elastase. AngII-induced AAAs formed near the location of maximum abdominal aortic curvature, and the leftward direction of expansion was correlated with the direction of suprarenal aortic motion. Elastase-induced AAAs formed in a region of low vessel curvature and had no repeatable direction of expansion. AngII significantly increased mean blood pressure (22.7 mm Hg, P<0.05), whereas both models showed a significant 2-fold decrease in aortic cyclic strain (P<0.05). Differences in patterns of elastin degradation and localization of fluorescent signal from protease-activated probes were also observed.. The direction of AngII aneurysm expansion correlated with the direction of motion, medial elastin dissection, and adventitial remodeling. Anterior infrarenal aortic motion correlated with medial elastin degradation in elastase-induced aneurysms. Results from both models suggest a relationship between aneurysm pathological features and aortic geometry and motion.

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Biomechanical Phenomena; Blood Pressure; Disease Progression; Elastin; Hypertension; Magnetic Resonance Imaging; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Models, Animal; Models, Cardiovascular; Ultrasonography

Abdominal aortic aneurysms (AAA) are an age-related vascular disease and an important cause of morbidity and mortality. In this study, we sought to determine whether the catalytic component of telomerase, telomerase reverse transcriptase (TERT), modulates angiotensin (Ang) II-induced AAA formation.. Low-density lipoprotein receptor-deficient (LDLr-/-) mice were lethally irradiated and reconstituted with bone marrow-derived cells from TERT-deficient (TERT-/-) mice or littermate wild-type mice. Mice were placed on a diet enriched in cholesterol, and AAA formation was quantified after 4 weeks of Ang II infusion. Repopulation of LDLr-/- mice with TERT-/- bone marrow-derived cells attenuated Ang II-induced AAA formation. TERT-deficient recipient mice revealed modest telomere attrition in circulating leukocytes at the study end point without any overt effect of the donor genotype on white blood cell counts. In mice repopulated with TERT-/- bone marrow, aortic matrix metalloproteinase-2 (MMP-2) activity was reduced, and TERT-/- macrophages exhibited decreased expression and activity of MMP-2 in response to stimulation with Ang II. Finally, we demonstrated in transient transfection studies that TERT overexpression activates the MMP-2 promoter in macrophages.. TERT deficiency in bone marrow-derived macrophages attenuates Ang II-induced AAA formation in LDLr-/- mice and decreases MMP-2 expression. These results point to a previously unrecognized role of TERT in the pathogenesis of AAA.

Topics: Angiotensin II; Animals; Aortic Aneurysm, Abdominal; Bone Marrow Transplantation; Cell Movement; Cells, Cultured; Elastin; Genotype; Macrophages; Male; Matrix Metalloproteinase 2; Mice; Mice, Knockout; Models, Animal; Receptors, LDL; Telomerase; Telomere

To examine whether a lack of prostaglandin E receptor 4 (EP4) on bone marrow-derived cells would increase local inflammation and enhance the formation of abdominal aortic aneurysm (AAA) in vivo.. Prostaglandin E(2) (PGE(2)) through activation of EP4, can mute inflammation. Hypercholesterolemic low-density lipoprotein receptor knockout (LDLR(-/-)) mice transplanted with either EP4(+/+) (EP4(+/+)/LDLR(-/-)) or EP4(-/-) (EP4(-/-)/LDLR(-/-)) bone marrow received infusions of angiotensin II to induce AAA. Deficiency of EP4 on bone marrow-derived cells increased the incidence (50% of male EP4(+/+)/LDLR(-/-) mice versus 88.9% of male EP4(-/-)/LDLR(-/-) mice developed AAA; and 22% of female EP4(+/+)/LDLR(-/-) mice versus 83.3% of female EP4(-/-)/LDLR(-/-) mice developed AAA) and severity of AAA, increased monocyte chemoattractant protein-1 (2.72-fold in males and 1.64-fold in females), and enhanced infiltration of macrophages (3.8-fold in males and 2.44-fold in females) and T cells (1.88-fold in males and 1.66-fold in females) into AAA lesions. Lack of EP4 on bone marrow-derived cells augmented elastin fragmentation, increased apoptotic markers, and decreased smooth muscle cell accumulation within AAA lesions.. Deficiency of EP4 on bone marrow-derived cells boosted inflammation and AAA formation induced by angiotensin II in hyperlipidemic mice. This study affirms the pathophysiologic importance of PGE(2) signaling through EP4 as an endogenous anti-inflammatory pathway involved in experimental aneurysm formation.

Topics: Angiotensin II; Animals; Aortic Aneurysm, Abdominal; Bone Marrow Cells; Bone Marrow Transplantation; Chemokine CCL2; Elastin; Female; Gene Deletion; Hyperlipidemias; Inflammation; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Models, Animal; Receptors, LDL; Receptors, Prostaglandin E, EP4 Subtype; Risk Factors

Although abdominal aortic aneurysms (AAA) can be potentially stabilized by inhibiting inflammatory cell recruitment and their release of proteolytic enzymes, active AAA regression is not possible without regeneration of new elastic matrix structures. Unfortunately, postneonatal vascular smooth muscle cells (SMCs), healthy, and likely more so, diseased cells, poorly synthesize or remodel elastic fibers, impeding any effort directed at regenerative AAA treatment. Previously, we determined the eleastogenic benefits of oligomers (HA-o; 4-6 mers) of the glycosaminoglycan, hyaluronan (HA) and transforming growth factor-β1 (TGF-β1) to healthy SMCs. Since AAAs are often diagnosed only late in development when matrix disruption is severe, we now determine if elastogenic upregulation of SMCs from late-stage AAAs (>100% diameter increase) is possible. AAAs were induced by perfusion of rat infrarenal aortae with porcine pancreatic elastase. Elastic matrix degradation, vessel expansion (∼120%), inflammatory cell infiltration, and enhanced activity of matrix-metalloproteases (MMPs) 2 and 9 resulted, paralleling human AAAs. Aneurysmal SMCs (EaRASMCs) maintained a diseased phenotype in 2D cell culture and exhibited patterns of gene expression different from healthy rat aortic SMCs (RASMCs). Relative to passage-matched healthy RASMCs, unstimulated EaRASMCs produced far less tropoelastin and matrix elastin. Exogenous TGF-β and HA-o (termed "factors") significantly decreased EaRASMC proliferation and enhanced tropoelastin synthesis, though only at the highest provided dose combination (20 mg/mL of HA-o, 10 ng/mL of TGF-β); despite such enhancement, tropoelastin amounts were only ∼40% of amounts synthesized by healthy RASMC cultures. Differently, elastic matrix synthesis was enhanced beyond amounts synthesized by healthy RASMCs (112%), even at lower doses of factors (2 mg/mL of HA-o and 5 ng/mL of TGF-β). The factors also enhanced elastic fiber deposition over untreated EaRASMC cultures and restored several genes whose expression was altered in EaRASMC cultures back to levels expressed by healthy RASMCs. However, the activity of MMPs 2 and 9 generated by EaRASMC cultures was unaffected by the factors/factor dose. The study confirms that SMCs from advanced AAAs can be elastogenically induced, although much higher doses of elastogenic factors are required for induction relative to healthy SMCs. Also, the factors do not appear to inhibit MMP activity, vital to preserve existing

Topics: Animals; Aorta; Aortic Aneurysm, Abdominal; Cell Proliferation; Disease Models, Animal; Disease Progression; Elastin; Extracellular Matrix; Fluorescent Antibody Technique; Gene Expression Profiling; Gene Expression Regulation; Humans; Male; Myocytes, Smooth Muscle; Oligonucleotide Array Sequence Analysis; Pancreatic Elastase; Perfusion; Phenotype; Protein Processing, Post-Translational; Rats; Rats, Sprague-Dawley; Staining and Labeling; Sus scrofa; Transforming Growth Factor beta

Regression of abdominal aortic aneurysms (AAAs) via regeneration of new elastic matrix is constrained by poor elastin synthesis by adult vascular cells and absence of methods to stimulate the same. We recently showed hyaluronan oligomers (HA-o) and TGF-β1 (termed elastogenic factors) to enhance elastin synthesis and matrix formation by healthy rat aortic smooth muscle cells (RASMCs). We also determined that these factors could likewise elastogenically induce aneurysmal RASMCs isolated from periadventitial CaCl(2)-injury induced rat AAAs (aRASMCs). However, the factor doses should be increased for these diseased cell types, as even when induced, elastic matrix amounts are roughly one order of magnitude lower than those produced by healthy RASMCs. We presently investigate the dose-specific elastogenic effects of HA-o (0-20  μg/mL) and TGF-β1 (0-10  ng/mL) factors on aRASMCs and compare their phenotype and elastogenic responses to those of human AAA-derived SMCs (aHASMCs); we seek to determine whether aRASMCs are appropriate surrogate cell types to study in the context of inducing elastic matrix regeneration within human AAAs. The periadventitial CaCl(2)-injury model of AAAs exhibits many of the pathological characteristics of human AAAs, including similarities in terms of decreased SMC contractile activity, enhanced proliferation, and reduced elastogenic capacity of aneurysmal SMCs (relative to healthy SMCs) when isolated and expanded in culture. Both aRASMCs and aHASMCs can be elastogenically stimulated by HA-o and TGF-β1 and show broadly similar trends in their dose-specific responses to these factors. However, compared with aHASMCs, aRASMCs appear to be far less elastogenically inducible. This may be due to differences in maturity of the AAAs studied, with the CaCl(2)-injury induced aortal expansion barely qualifying as an aneurysm and the human AAA representing a more well-developed condition. Further study of SMCs from stage-matched CaCl(2)-injury induced rat aortal expansions and human AAAs will be necessary to more rigorously evaluate their basal and induced elastogenic responses.

Topics: Animals; Aorta; Aortic Aneurysm, Abdominal; Biomarkers; Calcium Chloride; Cell Proliferation; Cells, Cultured; Disease Progression; Elastin; Extracellular Matrix; Fluorescent Antibody Technique; Humans; Hyaluronic Acid; Male; Middle Aged; Models, Biological; Myocytes, Smooth Muscle; Phenotype; Protein Processing, Post-Translational; Rats; Rats, Sprague-Dawley; Staining and Labeling; Transforming Growth Factor beta1

Despite rapid expansion of our knowledge of vascular adaptation, developing patient-specific models of diseased arteries is still an open problem. In this study, we extend existing finite element models of stress-mediated growth and remodelling of arteries to incorporate a medical image-based geometry of a healthy aorta and, then, simulate abdominal aortic aneurysm. Degradation of elastin initiates a local dilatation of the aorta while stress-mediated turnover of collagen and smooth muscle compensates the loss of elastin. Stress distributions and expansion rates during the aneurysm growth are studied for multiple spatial distribution functions of elastin degradation and kinetic parameters. Temporal variations of the degradation function are also investigated with either direct time-dependent degradation or stretch-induced degradation as possible biochemical and biomechanical mechanisms for elastin degradation. The results show that this computational model has the capability to capture the complexities of aneurysm progression due to variations of geometry, extent of damage and stress-mediated turnover as a step towards patient-specific modelling.

Topics: Aortic Aneurysm, Abdominal; Biomechanical Phenomena; Blood Vessels; Collagen; Elastin; Finite Element Analysis; Humans; Stress, Physiological

The causality of the associations between cellular and mechanical mechanisms of abdominal aortic aneurysm (AAA) formation has not been completely defined. Because reactive oxygen species are established mediators of AAA growth and remodeling, our objective was to investigate oxidative stress-induced alterations in aortic biomechanics and microstructure during subclinical AAA development. We investigated the mechanisms of AAA in an angiotensin II (ANG II) infusion model of AAA in apolipoprotein E-deficient (apoE(-/-)) mice that overexpress catalase in vascular smooth muscle cells (apoE(-/-)xTg(SMC-Cat)). At baseline, aortas from apoE(-/-)xTg(SMC-Cat) exhibited increased stiffness and the microstructure was characterized by 50% more collagen content and less elastin fragmentation. ANG II treatment for 7 days in apoE(-/-) mice altered the transmural distribution of suprarenal aortic circumferential strain (quantified by opening angle, which increased from 130 ± 1° at baseline to 198 ± 8° after 7 days of ANG II treatment) without obvious changes in the aortic microstructure. No differences in aortic mechanical behavior or suprarenal opening angle were observed in apoE(-/-)xTg(SMC-Cat) after 7 days of ANG II treatment. These data suggest that at the earliest stages of AAA development H(2)O(2) is functionally important and is involved in the control of local variations in remodeling across the vessel wall. They further suggest that reduced elastin integrity at baseline may predispose the abdominal aorta to aneurysmal mechanical remodeling.

Topics: Analysis of Variance; Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; Biomechanical Phenomena; Blood Pressure; Catalase; Collagen; Disease Models, Animal; Elastin; Hydrogen Peroxide; Mice; Mice, Knockout; Mice, Transgenic; Stress, Mechanical; Time Factors; Up-Regulation

Abdominal aortic aneurysms (AAAs) expand as a consequence of extracellular matrix destruction, and vascular smooth muscle cell (VSMC) depletion. Transforming growth factor (TGF)-beta 1 overexpression stabilizes expanding AAAs in rat. Cyclosporine A (CsA) promotes tissue accumulation and induces TGF -beta1 and, could thereby exert beneficial effects on AAA remodelling and expansion. In this study, we assessed whether a short administration of CsA could durably stabilize AAAs through TGF-beta induction. We showed that CsA induced TGF-beta1 and decreased MMP-9 expression dose-dependently in fragments of human AAAs in vitro, and in animal models of AAA in vivo. CsA prevented AAA formation at 14 days in the rat elastase (diameter increase: CsA: 131.9±44.2%; vehicle: 225.9±57.0%, P = 0.003) and calcium chloride mouse models (diameters: CsA: 0.72±0.14 mm; vehicle: 1.10±0.11 mm, P = .008), preserved elastic fiber network and VSMC content, and decreased inflammation. A seven day administration of CsA stabilized formed AAAs in rats seven weeks after drug withdrawal (diameter increase: CsA: 14.2±15.1%; vehicle: 45.2±13.7%, P = .017), down-regulated wall inflammation, and increased αSMA-positive cell content. Co-administration of a blocking anti-TGF-beta antibody abrogated CsA impact on inflammation, αSMA-positive cell accumulation and diameter control in expanding AAAs. Our study demonstrates that pharmacological induction of TGF-beta1 by a short course of CsA administration represents a new approach to induce aneurysm stabilization by shifting the degradation/repair balance towards healing.

Topics: Animals; Aortic Aneurysm, Abdominal; Calcium Chloride; Cyclosporine; Disease Models, Animal; Elastin; Humans; Inflammation; Male; Matrix Metalloproteinase 9; Mice; Mice, Inbred C57BL; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Pancreatic Elastase; Rats; Rats, Wistar; Tissue Inhibitor of Metalloproteinase-1; Transforming Growth Factor beta

Peroxisome proliferator-activated receptor-γ (PPARγ) plays an important role in the vasculature; however, the role of PPARγ in abdominal aortic aneurysms (AAA) is not well understood. We hypothesized that PPARγ in smooth muscle cells (SMCs) attenuates the development of AAA. We also investigated PPARγ-mediated signaling pathways that may prevent the development of AAA.. We determined whether periaortic application of CaCl(2) renders vascular SMC-selective PPARγ knockout (SMPG KO) mice more susceptible to destruction of normal aortic wall architecture.. There is evidence of increased vessel dilatation in the abdominal aorta 6 weeks after 0.25M periaortic CaCl(2) application in SMPG KO mice compared with littermate controls (1.4 ± 0.3 mm [n = 8] vs 1.1 ± 0.2 mm [n = 7]; P = .000119). Results from SMPG KO mice indicate medial layer elastin degradation was greater 6 weeks after abluminal application of CaCl(2) to the abdominal aorta (P < .01). Activated cathepsin S, a potent elastin-degrading enzyme, was increased in SMPG KO mice vs wild-type controls. To further identify a role of PPARγ signaling in reducing the development of AAA, we demonstrated that adenoviral-mediated PPARγ overexpression in cultured rat aortic SMCs decreases (P = .022) the messenger RNA levels of cathepsin S. In addition, a chromatin immunoprecipitation assay detected PPARγ bound to a peroxisome proliferator-activated receptor response element (PPRE) -141 to -159 bp upstream of the cathepsin S gene sequence in mouse aortic SMCs. Also, adenoviral-mediated PPARγ overexpression and knockdown in cultured rat aortic SMCs decreases (P = .013) and increases (P = .018) expression of activated cathepsin S. Finally, immunohistochemistry demonstrated a greater inflammatory infiltrate in SMPG KO mouse aortas, as evidenced by elevations in F4/80 and tumor necrosis factor-α expression.. In this study, we identify PPARγ as an important contributor in attenuating the development of aortic aneurysms by demonstrating that loss of PPARγ in vascular SMCs promotes aortic dilatation and elastin degradation. Thus, PPARγ activation may be potentially promising medical therapy in reducing the risk of AAA progression and rupture.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Binding Sites; Calcium Chloride; Cathepsins; Cells, Cultured; Dilatation, Pathologic; Disease Models, Animal; Elastin; Enzyme Activation; Inflammation; Mice; Mice, Knockout; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; PPAR gamma; Promoter Regions, Genetic; Rats; RNA Interference; RNA, Messenger; Signal Transduction; Time Factors; Transfection

Abdominal aortic aneurysms (AAA) are characterized by structural alterations of the aortic wall resulting from the degradation of elastic fibres and an increase of collagen/elastin ratio. In this study we investigated the chain dynamics of AAA tissues by two techniques generally used for the characterization of polymers, Differential scanning calorimetry (DSC) and thermally stimulated currents (TSC), and we correlated the obtained data with biochemical analyses. The thermal denaturation of collagen observed by DSC allowed us to evaluate the thermal stability of the triple helix domain: notable modifications were evidenced between collagen from control tissue and collagen from AAA, particularly concerning the thermal denaturation. The dielectric analysis of pathologic aortic walls by TSC revealed a relevant change of collagen mobility in AAA, with the occurrence of a specific mode of relaxation between -60 and -40°C. Biochemical, thermal, and dielectric results are compatible with increase of new collagen deposition and/or impairment of the collagen phase stability in the extracellular matrix of AAAs.

Topics: Aged; Amino Acids; Aorta; Aortic Aneurysm, Abdominal; Calorimetry, Differential Scanning; Collagen; Collagenases; Elastin; Female; Humans; Male; Middle Aged; Pepsin A; Protein Denaturation; Temperature

To develop methods to quantify cyclic strain, motion, and curvature of the murine abdominal aorta in vivo.. C57BL/6J and apoE(-/-) mice underwent three-dimensional (3D) time-of-flight MR angiography to position cardiac-gated 2D slices at four locations along the abdominal aorta where circumferential cyclic strain and lumen centroid motion were calculated. From the 3D data, a centerline through the aorta was created to quantify geometric curvature at 0.1-mm intervals. Medial elastin content was quantified with histology postmortem. The location and shape of abdominal aortic aneurysms (AAAs), created from angiotensin II infusion, were evaluated qualitatively.. Strain waveforms were similar at all locations and between groups. Centroid motion was significantly larger and more leftward above the renal vessels than below (P < 0.05). Maximum geometric curvature occurred slightly proximal to the right renal artery. Elastin content was similar around the circumference of the vessel. AAAs developed in the same location as the maximum curvature and grew in the same direction as vessel curvature and motion.. The methods presented provide temporally and spatially resolved data quantifying murine aortic motion and curvature in vivo. This noninvasive methodology will allow serial quantification of how these parameters influence the location and direction of AAA growth.

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; Elastin; Genotype; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Motion; Time Factors

During arterial aneurysm formation, levels of the membrane-anchored matrix metalloproteinase, MT1-MMP, are elevated dramatically. Although MT1-MMP is expressed predominately by infiltrating macrophages, the roles played by the proteinase in abdominal aortic aneurysm (AAA) formation in vivo remain undefined. Using a newly developed chimeric mouse model of AAA, we now demonstrate that macrophage-derived MT1-MMP plays a dominant role in disease progression. In wild-type mice transplanted with MT1-MMP-null marrow, aneurysm formation induced by the application of CaCl2 to the aortic surface was almost completely ablated. Macrophage infiltration into the aortic media was unaffected by MT1-MMP deletion, and AAA formation could be reconstituted when MT1-MMP+/+ macrophages, but not MT1-MMP+/+ lymphocytes, were infused into MT1-MMP-null marrow recipients. In vitro studies using macrophages isolated from either WT/MT1-MMP-/- chimeric mice, MMP-2-null mice, or MMP-9-null mice demonstrate that MT1-MMP alone plays a dominant role in macrophage-mediated elastolysis. These studies demonstrate that destruction of the elastin fiber network during AAA formation is dependent on macrophage-derived MT1-MMP, which unexpectedly serves as a direct-acting regulator of macrophage proteolytic activity.

Topics: Animals; Aorta; Aortic Aneurysm, Abdominal; Calcium Chloride; Disease Models, Animal; Elastin; Humans; Macrophages; Matrix Metalloproteinase 13; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Mice; Mice, Knockout

Clinical evidence links increased aortic collagen content and stiffness to abdominal aortic aneurysm (AAA) formation. However, the possibility that excess collagen contributes to AAA formation remains untested. We investigated the hypothesis that augmented collagen promotes AAA formation, and employed apoE-null mice expressing collagenase-resistant mutant collagen (Col(R/R)/apoE(-/-)), heterozygote (Col(R/+)/apoE(-/-)), or wild-type collagen (Col(+/+)/apoE(-/-)) infused with angiotensin II to induce AAA. As expected, the aortas of Col(R/R)/apoE(-/-) mice contained more interstitial collagen than those from the other groups. Angiotensin II treatment elicited more AAA formation in Col(R/R)/apoE(-/-) mice than Col(R/+)/apoE(-/-) or Col(+/+)/apoE(-/-) mice. Aortic circumferences correlated positively with collagen content, determined by picrosirius red and Masson trichrome staining. Mechanical testing of aortas of Col(R/R)/apoE(-/-) mice showed increased stiffness and susceptibility to mechanical failure compared to those of Col(+/+)/apoE(-/-) mice. Optical analysis further indicated altered collagen fiber orientation in the adventitia of Col(R/R)/apoE(-/-) mice. These results demonstrate that collagen content regulates aortic biomechanical properties and influences AAA formation.

Topics: Analysis of Variance; Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; Biomechanical Phenomena; Collagen; Collagenases; Connective Tissue; Elastin; Histocytochemistry; Male; Mice; Mice, Inbred C57BL; Mice, Knockout

The objective of this work was to assess whether selective proteolysis of elastin and/or collagen in a porcine aorta followed by mechanical creep loading would result in an aneurysm-like permanent tissue stretch. The underlying motivations were to (1) test the feasibility of developing an in vitro abdominal aortic aneurysm (AAA) model, and (2) understand what role, if any, that passive creep-induced stretching plays in aneurysmal dilation. Multiple circumferentially oriented flat specimen strips were cut from the porcine thoracic aorta of ten adult pigs. Specimens were subjected to one of six treatment protocols: Untreated controls (UC;N=23), complete elastin degradation (E;N=10), partial elastin degradation (E(p);N=10), partial collagen degradation (C(p);N=22), and partial degradation of both elastin and collagen (E(p)+C(p);N=3). All specimens were then subjected to cyclic creep (10 min/cycle) with increasing load amplitude until failure. The zero-load strain prior to the creep cycle where failure occurred was defined as load-induced plastic strain. The plastic strain induced by treatment alone, creep loading alone and the total was determined for all specimens. The total plastic strain was significantly greater for E (mean +/- SD = 48.2 +/-17.6,p<0.005), E(p)(41.6+/-11.1,p<0.0005), but not for E(p)+C(p)(48.9+/-21.6,p=0.17) and C(p)(22.2+/-12.8,p=0.14) compared to UC (17.7+/-6.1). Of the total plastic strain, treatment-induced plastic strain was high for those specimens subjected to partial or total elastin degradation (E,E(p),E(p)+C(p)), but not for those where elastin was intact (C(p)). However, load-induced plastic strain in the treated specimens was not different in any of the treated groups compared to controls. Maximum total plastic strain of 78.6% was induced in one porcine aortic tissue from the E group. Even this is far lower than what would be needed for creating a realistic in vitro AAA model. Our findings do not support the feasibility of developing an in vitro AAA by enzymolysis followed by passive stretching of the aorta. The findings also suggest that AAA formation is unlikely to be a passive creep-induced stretching of a proteolytically degraded aortic wall as conventional thinking may suggest, but rather may be predominantly due to growth and remodeling of the aortic wall.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Biomechanical Phenomena; Collagen; Elasticity; Elastin; Humans; Materials Testing; Models, Biological; Stress, Mechanical; Swine

Abdominal aortic aneurysm (AAA) wall is characterized by degradation of extracellular matrix through matrix metalloproteinases (MMPs), chronic inflammatory cell infiltration and extensive neovascularization. So far, MMP expression within AAA wall in association with infiltrates and neovascularization has not yet been studied.. Vessel walls of 15 AAA patients and 8 organ donors were analyzed by immunohistochemistry for expression of various MMPs (MMP-1, -2, -3, -7, -8, -9, -12 and -13) in all cells located within the AAAs and correlated with infiltrates and neovascularization.. Luminal endothelial cells (ECs) were positive for MMP-1, -3 and -9, ECs of mature neovessels were furthermore positive for MMP-2. Immature neovessels expressed all MMPs tested except for MMP-13. Aortic medial smooth muscle cells (SMCs) expressed MMP-1, -2, -3 and -9, SMCs of mature neovessels, only MMP-1, -3 and -9. Inflammatory infiltrates expressed all MMPs tested except for MMP-2, macrophages expressed all MMPs. Infiltrates were composed mainly of B cells (58.5 +/- 10.9%) and T lymphocytes (26.3 +/- 9.5%). Furthermore, significant inverse correlations were found between the amounts of inflammatory cells, neovessels and collagen/elastin content of the aortic vessel wall (r = +0.806/p < 0.001, r = -0.650/p = 0.012, r = -0.63/p < 0.015; respectively).. Inflammatory infiltrates and invading neovessels are relevant sources of MMPs in the AAA wall and may substantially contribute to aneurysm wall instability.

Topics: Aged; Aged, 80 and over; Aortic Aneurysm, Abdominal; Collagen; Elastin; Endothelial Cells; Female; Humans; Immunohistochemistry; Inflammation; Male; Matrix Metalloproteinases; Middle Aged; Myocytes, Smooth Muscle; Neovascularization, Pathologic

The natural history of abdominal aortic aneurysm (AAA) is wall remodelling potentially leading to a final rupture. The pathogenesis of AAA appears to be multifactorial. The aim of this pilot prospective study was to assess the relationship between the thickness of the thrombus within the abdominal aortic aneurysm, intramural pH and local elastin degradation.. The AAA size, intraluminal thrombus (ILT) morphology and location were evaluated in 206 consecutive patients. Thirty patients with large AAA (aortic diameter > or = 50 mm) and adjacent ILT with the thinnest part < or = 10 mm and thickest > or = 25 mm, measured in the region of the maximum diameter of AAA, were included for further study. During AAA surgery intramural pH measurements were performed and specimens taken from both thin thrombus-covered and thick thrombus-covered wall for computerized morphometric analysis.. Mean intramural pH value was 7.21 +/- 0.18 for the wall covered by thick ILT and 7.64 +/- 0.10 for the thin one (P < 0.001). Computerized morphometric analysis demonstrated that elastin fibres in the thin thrombus-covered wall were decreased in size (for width--P < 0.0001, for length--P < 0.13), irregularly orientated (P < 0.000001) and the amount of fibres was reduced when compared to the wall covered by thick ILT (P < 0.0004).. A strong relationship between intramural pH and elastin net destruction suggests that the local alkaline status within the thin thrombus-covered part of the aneurysm wall is contributing to the elastinolytic process.

Topics: Adult; Aged; Aged, 80 and over; Aortic Aneurysm, Abdominal; Elastin; Female; Humans; Hydrogen-Ion Concentration; Male; Middle Aged; Pilot Projects; Radiography; Thrombosis

Maintaining the integrity of arterial elastin is vital for the prevention of abdominal aortic aneurysm (AAA) development. We hypothesized that in vivo stabilization of aortic elastin with pentagalloyl glucose (PGG), an elastin-binding polyphenol, would interfere with AAA development.. Safety and efficacy of PGG treatment were first tested in vitro using cytotoxicity, elastin stability, and PGG-elastin interaction assays. For in vivo studies, the efficacy of PGG was evaluated within a well-established AAA model in rats on the basis of CaCl2-mediated aortic injury. With this model, PGG was delivered periadventitially at 2 separate time points during the course of AAA development; aortic diameter, elastin integrity, and other pathological aspects were monitored and evaluated in PGG-treated aortas compared with saline-treated control aortas. Our results show that a one-time periadventitial delivery of noncytotoxic levels of PGG inhibits elastin degeneration, attenuates aneurysmal expansion, and hinders AAA development in rats without interfering with the pathogenic mechanisms typical of this model, namely inflammation, calcification, and high metalloproteinase activities. PGG binds specifically to arterial elastin and, in doing so, preserves the integrity of elastic lamellae despite the presence of high levels of proteinases derived from inflammatory cells.. Periadventitial administration of PGG hinders the development of AAA in a clinically relevant animal model. Stabilization of aortic elastin in aneurysm-prone arterial segments offers great potential toward the development of safe and effective therapies for AAAs.

Topics: Administration, Topical; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Calcinosis; Calcium Chloride; Cells, Cultured; Disease Models, Animal; Disease Progression; Drug Evaluation, Preclinical; Elastin; Fibroblasts; Hydrolyzable Tannins; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Protein Denaturation; Rats; Rats, Sprague-Dawley

Experimental abdominal aortic aneurysm (AAA) development can be pharmacologically suppressed by inhibiting matrix metalloproteinase-9 (MMP-9). Cyclooxygenase-2 (COX-2) inhibitors are potent anti-inflammatory agents that have been demonstrated to inhibit experimental aneurysm development. We hypothesized that treatment with MF-tricyclic, a selective COX-2 inhibitor, incorporated into rodent chow would inhibit aneurysm development in a rat AAA model.. Twelve male Sprague Dawley rats underwent induction of experimental AAA using intra-aortic porcine elastase infusion. Six rats received control feed, and six received MF-tricyclic rodent chow for a period of 14 days. Aortic diameters were measured pre- and postinfusion as well as at harvest. Aortic tissue samples were evaluated by real-time polymerase chain reaction (RT-PCR) for MMP-9, by immunohistochemistry for elastin.. Elastase infusion produced AAA in all untreated rats. At 14 days MF-tricyclic-treated rats had significantly reduced aortic diameter (1.9 +/- 0.1 mm versus 2.4 +/- 0.0 mm, P = 0.00001). Percent increase in aortic diameter was also significantly less in animals receiving MF-tricyclic (65.7 +/- 8.5% versus 132.3 +/- 7.3%, P = 0.0001). RT-PCR demonstrated a decrease in the mean expression of MMP-9 in the treated animals (0.414 ng of RNA versus 1.114 ng of RNA) (P = 0.07). Sections stained for elastin demonstrated preserved elastin integrity in MF-tricyclic treated aortas.. COX-2 inhibition helps to retard the growth of experimental AAAs possibly through inhibition of MMP-9. Experimentally treated animals demonstrated smaller aortic diameters and lower levels of tissue MMP-9 when compared to untreated animals. Selective COX-2 inhibition may offer an additional method to pharmacologically inhibit AAAs.

Topics: Animals; Aortic Aneurysm, Abdominal; Cyclooxygenase 2 Inhibitors; Elastin; Furans; Male; Matrix Metalloproteinase 9; Rats; Rats, Sprague-Dawley

Embryo-like gingival healing properties are attributed to the gingival fibroblast (GF) and could be used as a model for other types of healing dysfunctions. Abdominal aortic aneurysm (AAA) formation is associated with elastin degradation and increase in matrix metalloproteinase (MMP)-9 activity. We aimed to validate the concept of using GF healing properties in arteries.. We evaluated MMP-9 and its tissue inhibitor (TIMP-1) in rabbit aortic rings cultured in collagen gels with or without GFs and observed throughout 21 days. We also performed cocultures of human smooth muscle cells (hSMCs) with either gingival, dermal, or adventitial fibroblasts, and alone (control). In control arteries, elastic fibers became spontaneously sparse. In presence of GFs, elastic fibers were preserved. There was a dramatically reduced protein level of MMP-9 in coculture of aorta and GFs, in contrast with control aorta. MMP-9 expression was unaffected by GFs. MMP-9 inhibition was related to increased TIMP-1 secretion, TIMP-1 forming a complex with MMP-9. Cell cocultures of hSMC with GFs showed similar results. Dermal and adventitial fibroblasts did not affect MMP-9.. Elastic fiber degradation was specifically preserved by GFs via reduction of MMP-9 protein level by increasing TIMP-1 synthesis. Vascular transfer of gingival fibroblasts could be a promising approach to treat AAA.

Topics: Animals; Aorta; Aortic Aneurysm, Abdominal; Cells, Cultured; Coculture Techniques; Elastin; Fibroblasts; Gingiva; Humans; Matrix Metalloproteinase 9; Rabbits; Tissue Inhibitor of Metalloproteinase-1

Because current therapy to treat abdominal aortic aneurysm (AAA), and particularly to manage small AAA, is limited to elective surgical repair, we explored less invasive molecular therapy by simultaneous inhibition of the transcription factors nuclear factor (NF)kappaB and ets using a decoy strategy. Both NFkappaB and ets were shown to be markedly activated in human AAA. In addition, NFkappaB- and ets-positive cells were increased in the aneurysm wall, and a part of the expression of NFkappaB and ets was detected in migrating macrophages. Thus, we used chimeric decoy oligodeoxynucleotides (ODNs) containing consensus sequences of both NFkappaB and ets binding sites to treat AAA. Inhibitory effects of chimeric decoy ODNs on matrix metalloproteinase-1 and -9 expression were confirmed by ex vivo experiments using a human aorta organ culture. To examine the regressive effect in a rabbit already-formed AAA model, transfection by wrapping a delivery sheet containing chimeric decoy ODNs around the aneurysm was performed 1 week after incubation with elastase. Importantly, treatment with chimeric decoy ODNs significantly decreased the size of AAA. Interestingly, significant preservation of elastic fibers was observed with chimeric decoy ODN treatment, accompanied by a reduction of matrix metalloproteinase-2 and -9 and induction of macrophage apoptosis. Regression of AAA was also associated with an increase in elastin and collagen type I and III synthesis in the aneurysm wall. Minimally invasive molecular therapy targeted to the inhibition of NFkappaB and ets is expected to be useful for AAA through the rebalance of matrix synthesis and degradation.

Topics: Animals; Aorta; Aortic Aneurysm, Abdominal; Apoptosis; Binding Sites; Collagen; Consensus Sequence; Disease Models, Animal; Elastin; Humans; Macrophages; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Molecular Mimicry; NF-kappa B; Oligodeoxyribonucleotides; Proto-Oncogene Protein c-ets-1; Rabbits

Abdominal aortic aneurysm (AAA), an inflammatory disease, involves leukocyte recruitment, immune responses, inflammatory cytokine production, vascular remodeling, neovascularization, and vascular cell apoptosis, all of which contribute to aortic dilatation. This study demonstrates that mast cells, key participants in human allergic immunity, participate in AAA pathogenesis in mice. Mast cells were found to accumulate in murine AAA lesions. Mast cell-deficient KitW-sh/KitW-sh mice failed to develop AAA elicited by elastase perfusion or periaortic chemical injury. KitW-sh/KitW-sh mice had reduced aortic expansion and internal elastic lamina degradation; decreased numbers of macrophages, CD3+ T lymphocytes, SMCs, apoptotic cells, and CD31+ microvessels; and decreased levels of aortic tissue IL-6 and IFN-gamma. Activation of mast cells in WT mice via C48/80 injection resulted in enhanced AAA growth while mast cell stabilization with disodium cromoglycate diminished AAA formation. Mechanistic studies demonstrated that mast cells participated in angiogenesis, aortic SMC apoptosis, and matrix-degrading protease expression. Reconstitution of KitW-sh/KitW-sh mice with bone marrow-derived mast cells from WT or TNF-alpha-/- mice, but not from IL-6-/- or IFN-gamma-/- mice, caused susceptibility to AAA formation to be regained. These results demonstrate that mast cells participate in AAA pathogenesis in mice by releasing proinflammatory cytokines IL-6 and IFN-gamma, which may induce aortic SMC apoptosis, matrix-degrading protease expression, and vascular wall remodeling, important hallmarks of arterial aneurysms.

Topics: Animals; Aorta; Aortic Aneurysm, Abdominal; Elastin; Humans; Interferon-gamma; Interleukin-6; Male; Mast Cells; Mice; Mice, Inbred C57BL; Mice, Knockout; Pancreatic Elastase; Proto-Oncogene Proteins c-kit; Tumor Necrosis Factor-alpha

To determine if treatment with hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) can influence the development of experimental abdominal aortic aneurysms (AAAs).. AAAs are associated with atherosclerosis, chronic inflammation, and matrix metalloproteinase (MMP)-mediated connective tissue destruction. Because statins exert antiinflammatory activities independent of their lipid-lowering effects, these agents may help suppress aneurysmal degeneration.. C57Bl/6 wild-type and hypercholesterolemic apoE-deficient mice underwent transient perfusion of the aorta with elastase followed by subcutaneous treatment with either 2 mg/kg simvastatin per day or vehicle. Aortic diameter (AD) was measured before and 14 days after elastase perfusion. The extent of aortic dilatation (DeltaAD) was determined with AAAs defined as DeltaAD >100%.. Wild-type mice treated with simvastatin exhibited a 21% reduction in DeltaAD and a 33% reduction in AAAs compared with vehicle-treated controls. Suppression of AAAs in simvastatin-treated mice was associated with preservation of medial elastin and vascular smooth muscle cells, as well as a relative reduction in aortic wall expression of MMP-9 and a relative increase in expression of TIMP-1. In hypercholesterolemic apoE-deficient mice, treatment with simvastatin was associated with a 26% reduction in DeltaAD and a 30% reduction in AAAs. Treatment with simvastatin had no effect on serum cholesterol levels in either normal or hypercholesterolemic mice.. Treatment with simvastatin suppresses the development of experimental AAAs in both normal and hypercholesterolemic mice. The mechanisms of this effect are independent of lipid-lowering and include preservation of medial elastin and smooth muscle cells, as well as altered aortic wall expression of MMPs and their inhibitors.

Topics: Animals; Aortic Aneurysm, Abdominal; Elastin; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hypercholesterolemia; Male; Matrix Metalloproteinases; Mice; Mice, Inbred C57BL; Models, Animal; Myocytes, Smooth Muscle; Simvastatin; Tissue Inhibitor of Metalloproteinases; Tunica Media

The pathophysiology of abdominal aortic aneurysms (AAA) is considered to be complicated. As matrix degradation contributes to the progression of AAA, the destruction and degradation of elastin fibers caused by an increase in matrix metalloproteinases (MMPs) plays a pivotal role in the development of AAA. Although ets, an essential transcription factor for angiogenesis, regulates MMPs, the role of ets in the development of AAA has not yet been clarified. Thus, we evaluated the role of ets in a rat AAA model using a decoy strategy. Transfection of ODN into AAA was performed by transient aortic perfusion of elastase and by wrapping the AAA in a delivery sheet containing decoy ODN. The inhibitory effect of ets decoy ODN on ets binding activity was confirmed by gel mobility shift assay. MMPs expression was decreased in the aorta transfected with ets decoy ODN as compared to scrambled decoy ODN. Also, ultrasound study demonstrated that elastase-induced aneurismal dilation was significantly suppressed by transfection of ets decoy ODN at 4 weeks after treatment as compared to scrambled decoy ODN. Moreover, the destruction of elastin fibers was inhibited in the aorta transfected with ets decoy ODN, accompanied by a reduction of MMPs expression. An inhibitory effect of decoy ODN on MMP expression was confirmed by ex vivo experiments showing that transfection of decoy ODN into an organ culture of human aorta resulted in significant inhibition of the secretion of both MMP-1 and MMP-9. Here, we demonstrated that ets may play a pivotal role in the progression of AAA through the activation of MMPs in a rat model. Ets might be a potential target to develop pharmacotherapy/gene therapy to treat AAA through the inhibition of MMPs.

Topics: Animals; Aortic Aneurysm, Abdominal; Elastin; Electrophoretic Mobility Shift Assay; Gene Expression Regulation, Enzymologic; Gene Transfer Techniques; Genetic Therapy; Humans; Male; Matrix Metalloproteinase 1; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors; Oligodeoxyribonucleotides; Organ Culture Techniques; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-ets; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; Transcription Factors

Abdominal aortic aneurysms (AAAs) are characterized by histologic signs of chronic inflammation, destructive remodeling of extracellular matrix, and depletion of vascular smooth muscle cells. We investigated the process of extracellular matrix remodeling by performing a genetic association study with polymorphisms in the genes for matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), and structural extracellular matrix molecules in AAA. Our hypothesis was that genetic variations in one or more of these genes contribute to greater or lesser activity of these gene products, and thereby contribute to susceptibility for developing AAAs.. DNA samples from 812 unrelated white subject (AAA, n = 387; controls, n = 425) were genotyped for 14 polymorphisms in 13 different candidate genes: MMP1(nt-1607), MMP2(nt-955), MMP3(nt-1612), MMP9(nt-1562), MMP10(nt+180), MMP12(nt-82), MMP13(nt-77), TIMP1(nt+434), TIMP1(rs2070584), TIMP2(rs2009196), TIMP3(nt-1296), TGFB1(nt-509), ELN(nt+422), and COL3A1(nt+581). Odds ratios and P values adjusted for gender and country of origin using logistic regression and stratified by family history of AAA were calculated to test for association between genotype and disease status. Haplotype analysis was carried out for the two TIMP1 polymorphisms in male subjects.. Analyses with one polymorphism per test without interactions showed an association with the two TIMP1 gene polymorphisms (nt+434, P = .0047; rs2070584, P = .015) in male subjects without a family history of AAA. The association remained significant when analyzing TIMP1 haplotypes (chi 2 P = .014 and empirical P = .009). In addition, we found a significant interaction between the polymorphism and gender for MMP10 ( P = .037) in cases without a family history of AAA, as well as between the polymorphism and country of origin for ELN ( P = .0169) and TIMP3 ( P = .0023) in cases with a family history of AAA.. These findings suggest that genetic variations in TIMP1, TIMP3, MMP10, and ELN genes may contribute to the pathogenesis of AAAs. Further work is needed to confirm the findings in an independent set of samples and to study the functional role of these variants in AAA. It is noteworthy that contrary to a previous study, we did not find an association between the MMP9 (nt-1562) polymorphism and AAA, suggesting genetic heterogeneity of the disease.. Abdominal aortic aneurysms (AAAs) are an important cardiovascular disease, but the genetic and environmental risk factors, which contribute to individual's risk to develop an aneurysm, are poorly understood. Histologically, AAAs are characterized by signs of chronic inflammation, destructive remodeling of the extracellular matrix, and depletion of vascular smooth muscle cells. We hypothesized that genes involved in these events could harbor changes that make individuals more susceptible to developing aneurysms. This study identified significant genetic associations between DNA sequence changes in tissue inhibitor of metalloproteinase 1 (TIMP1), TIMP3, matrix metalloproteinase 10 (MMP10) and elastin (ELN) genes, and AAA. The results will require confirmation using an independent set of samples. After replication it is possible that these sequence changes in combination with other risk factors could be used in the future to identify individuals who are at increased risk for developing an AAA.

Topics: Aortic Aneurysm, Abdominal; Elastin; Extracellular Matrix; Female; Genetic Predisposition to Disease; Humans; Linkage Disequilibrium; Male; Matrix Metalloproteinase 10; Metalloendopeptidases; Polymorphism, Genetic; Tissue Inhibitor of Metalloproteinase-1; Tissue Inhibitor of Metalloproteinase-3; Tissue Inhibitor of Metalloproteinases

Topics: Aneurysm; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Elastin; Embryonic and Fetal Development; Female; Humans; Iliac Artery; Male; Placenta

Elastin, an extracellular matrix protein, constitutes about 30% of the dry weight of the arteries. Elastolysis induced by inflammatory processes is active in chronic arterial diseases. However, elastogenesis in arterial diseases has received little attention. In this work we hypothesized that disordered elastogenesis is active in matrix remodeling in atheroma and abdominal aortic aneurysm (AAA).. Human AAA and atheroma have 4- to 6-fold more tropoelastin protein than nondiseased arteries. The smooth muscle cell-containing media and fibrous cap of atherosclerotic arteries contain ordered mature elastin, whereas macrophage (MPhi)-rich regions often have disorganized elastic fibers. Surprisingly, in addition to smooth muscle cells, MPhis in diseased arteries also produce the elastin precursor tropoelastin, as shown by double immunostaining, in situ hybridization, and reverse transcription-polymerase chain reaction for tropoelastin mRNA. Cultured monocyte-derived MPhis can express the elastin gene. AAA have 9-fold but atheroma only 1.6-fold lower levels of desmosine, a marker for mature cross-linked elastin, than normal arteries.. This study demonstrates ongoing but often ineffective elastogenesis in arterial disease and establishes human macrophages as a novel source for this important matrix protein. These results have considerable import for understanding mechanisms of extracellular matrix remodeling in arterial diseases.

Topics: Aorta; Aortic Aneurysm, Abdominal; Arteriosclerosis; Cells, Cultured; Desmosine; Elastin; Extracellular Matrix Proteins; Humans; In Situ Hybridization; Macrophages; RNA, Messenger; Tropoelastin

Clinical evidence indicates that hemodynamic conditions influence abdominal aortic aneurysm (AAA) disease. We modified blood flow to evaluate the effects of wall shear stress (WSS) and relative wall strain (RWS) on aneurysm structure and cellularity.. Rodent AAAs were created with porcine pancreatic elastase infusion. In group 1 AAA WSS was increased with left femoral arteriovenous fistula creation, whereas in group 2 AAA WSS was decreased with left iliac artery ligation. Aortic flow, wall motion, and blood pressure were recorded in both groups. AAA diameter, endothelial and smooth muscle cellularity (CD31 and alpha-smooth muscle actin immunostaining), markers for cell proliferation (5-bromodeoxyuridine), endothelial and smooth muscle cell growth factor production (vascular endothelial growth factor-D and platelet-derived growth factor-beta, respectively), and apoptosis (deoxyuridine triphosphate nick end-labeled [TUNEL] stain) were compared between groups when the animals were killed.. Arteriovenous fistula creation increased WSS (high-flow AAA) by 300% and RWS by 150%. Iliac ligation reduced WSS (low-flow AAA) by 60%. Neither procedure significantly altered systolic, diastolic, or mean aortic pressure. When the animals were killed 7 days after elastase infusion, low-flow AAAs were significantly larger than high-flow AAAs. High-flow AAAs also contained more endothelial cells and smooth muscle cells, and evidence of increased growth factor production, cell proliferation, and decreased apoptosis. No difference in type or severity of AAA inflammatory cell infiltrate was noted between groups.. High flow conditions stimulate endothelial cell and smooth muscle cell proliferation in experimental aneurysms. Enhanced cellularity may stabilize aortic integrity, limiting aneurysm growth. Increased lower extremity activity may prevent or retard AAA disease through salutary effects on aortic remodeling mediated by endothelial cells and smooth muscle cells.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Blood Flow Velocity; Blood Pressure; Cell Differentiation; Collagen; Disease Models, Animal; Disease Progression; Elastin; Endothelial Growth Factors; Endothelium, Vascular; Models, Cardiovascular; Myocytes, Smooth Muscle; Rats; Rats, Inbred Strains; Receptors, Vascular Endothelial Growth Factor; Shear Strength; Vascular Endothelial Growth Factor D

To evaluate the effects doxycycline (Dox) in animal models of early abdominal aortic aneurysm.. Of 43 male Wistar rats, 33 underwent intraluminal perfusion of the abdominal aorta with thioglycolate plus plasmin to reproduce early aortic aneurysm. These rats then were treated for 7 days with subcutaneous injections of Dox or saline. The 10 remaining rats underwent intra-aortic perfusion with saline and were injected subcutaneously with saline. On day 7, the rats were killed after abdominal aortic diameters were measured. Some aortic specimens were examined microscopically after elastica van Gieson (EVG) and hematoxylin-eosin (H&E) staining. In other specimens, the matrix metalloproteinase (MMP) activity in tissue extracts was evaluated by gelatin zymography.. Among the thioglycolate plus plasmin-perfused rats, the degree of aortic dilation was less in Dox-treated than in saline-treated rats. EVG staining indicated that Dox maintained a nearly normal pattern of elastic lamellae and normal medial elastin thickness. The aortic inflammatory response was not suppressed by Dox in H&E staining. In gelatin zymography, Dox reduced the MMP-9 activity, but did not significantly change either MMP-2 or the percentage of activated MMP-2.. Dox inhibited experimental aneurysmal dilation by preserving medial elastin. This effect involved the suppression of MMP-9 but not of the MMP-2 activity.

Topics: Animals; Anti-Bacterial Agents; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Disease Models, Animal; Doxycycline; Elastin; Male; Rats; Rats, Wistar

to test the hypothesis that there is a negative association between serum levels of lipoprotein(a) (Lp(a)) and elastin-derived peptides (EDP) as well as matrix metalloproteinase (MMP)-9 activation in the aneurysm wall in patients with asymptomatic abdominal aortic aneurysms (AAA).. from 30 patients operated for asymptomatic AAAs, preoperative serum samples and AAA biopsies were collected. Lp(a) (mg/L) and EDP (ng/ml) in serum were measured by enzyme linked immunosorbent assays. MMP-9 activity (arbitrary units) in the AAA wall was measured by gelatin zymography and the ratio: active MMP-9/total MMP-9 were calculated.. there was a significant negative correlation (Spearman's rho) between serum levels of Lp(a) and EDP (r= -0.707, p<0.001), as well as the share of activated MMP-9 (r= -0.461, p=0.01) in the AAA wall.. this preliminary study indicate that Lp(a) inhibit elastolysis in asymptomatic AAA.

Topics: Aged; Aged, 80 and over; Aortic Aneurysm, Abdominal; Elastin; Enzyme Activation; Enzyme-Linked Immunosorbent Assay; Female; Humans; Lipoprotein(a); Male; Matrix Metalloproteinase 9; Middle Aged; Peptides

Abdominal aortic aneurysms (AAAs) occur in 5-7% of people over age 60 in the United States. Early intervention in the disease process could have a significant impact on the incidence of complications and on patient survival, but identifying incipient aneurysms can be difficult. ApoE knockout mice develop AAAs following infusion of angiotensin II (AngII) by osmotic minipump into the subcutaneous space of mice at doses ranging from 500 to 1000 ng kg(-1) min(-1) for 7-28 days. These mice are used as models of AAA development. This study tested the hypothesis that near-IR spectrometry and PCR can determine AngII dose (SEE = 26 ng kg(-1) min(-1), SEP = 37 ng kg(-1) min(-1), r2 = 0.99) and collagen/elastin (C/E) ratio (SEE = 0.38, SEP = 0.39, r2 = 0.85) in mouse aortas.

Topics: Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; Calibration; Collagen; Elastin; Mice; Mice, Inbred C57BL; Mice, Knockout; Reverse Transcriptase Polymerase Chain Reaction; Spectroscopy, Near-Infrared

Cardiovascular diseases, such as atherosclerosis and hypertension, are associated with arterial stiffening. Previous studies showed that ANG II exacerbated atherosclerosis and induced hypertension and aneurysm formation in apolipoprotein E-deficient (apoE-KO) mice. The aim of the present study was to examine the effects of chronic treatment of ANG II on the arterial elastic properties in apoE-KO mice. We hypothesized that ANG II will injure the arterial wall resulting in increased arterial stiffening. Male apoE-KO mice were infused with either ANG II (1.44 mg. kg(-1). day(-1)) or vehicle (PBS) for 30 days. ANG II treatment accelerated atherosclerosis in the carotid artery by sixfold (P < 0.001) and increased blood pressure by 30% (P < 0.05). Additionally, our data demonstrated that ANG II increased arterial stiffening using both in vivo and in vitro methods. ANG II significantly increased pulse wave velocity by 36% (P < 0.01) and decreased arterial elasticity as demonstrated by a more than 900% increase in maximal stiffening (high strain Young's modulus) compared with vehicle (P < 0.05). These functional changes were correlated with morphological and biochemical changes as demonstrated by an increase in collagen content (60%), a decrease in elastin content (74%), and breaks in the internal elastic lamina in the aortic wall. In addition, endothelium-independent vasorelaxation to sodium nitroprusside was impaired in the aortic rings of ANG II-treated mice compared with vehicle. Thus, the present data indicate that ANG II injures the artery wall in multiple ways and arterial stiffening may be a common outcome of ANG II-induced arterial damage.

Topics: Acetylcholine; Angiotensin II; Animals; Aorta; Aortic Aneurysm, Abdominal; Apolipoproteins E; Arteriosclerosis; Blood Pressure; Carotid Arteries; Collagen; Drug Administration Schedule; Elasticity; Elastin; Endothelium, Vascular; Male; Mice; Mice, Knockout; Nitroprusside

Inflammation and elastinolysis are observed in the media of abdominal aortic aneurysms (AAAs) where vascular smooth muscle cell (VSMC) density is decreased. In contrast, elastin and VSMCs are preserved in the noninflammatory media of stenotic atherosclerotic lesions. We have tested the hypothesis that VSMCs exert a protective effect against inflammation and proteolysis in a model of AAA in rats, in which medial elastin degradation is driven by inflammation and matrix metalloproteinases.. Decellularized guinea pig aortas (xenografts) were implanted orthotopically into Fischer-344 rats and seeded with a suspension of rat VSMCs syngeneic to the rat recipient, or were infused with culture medium as a control. Diameter and elastin in the media were quantified 8 weeks after implantation. Inflammation, matrix metalloproteinase (MMP) and tissue inhibitor of matrix metalloproteinase (TIMP) expression were analyzed 1 and 2 weeks after implantation.. VSMC addition prevented AAA formation (mean +/- standard deviation diameter increase: 198.2% +/- 106.6% vs 35.3% +/- 17.8%, P =.009), elastin degradation, and decreased infiltration by monocyte-macrophages. Reverse-transcriptase polymerase chain reaction, zymography and reverse zymography for MMP-2, MMP-9, TIMP-1, TIMP-2, and TIMP-3 demonstrated a shift of the proteolytic-antiproteolytic balance upon addition of VSMCs. Transcriptional changes were observed in the adventitia, although seeded VSMCs remained located in the intima.. VSMCs exert a paracrine effect on the adventitia that participate in artery wall homeostasis against inflammation and proteolysis. Failure of this protective mechanism results in AAA formation. The understanding of the molecular mechanisms underlying VSMC protective effect may represent a new approach in the treatment of aneurysm and plaque rupture.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Elastin; Guinea Pigs; Inflammation; Male; Matrix Metalloproteinases; Muscle, Smooth, Vascular; Protease Inhibitors; Rats; Rats, Inbred F344; RNA, Messenger; Tissue Inhibitor of Metalloproteinases; Transplantation, Heterologous

To measure serum concentrations of elastin-derived peptides (S-EDP) in patients with aneurysmal, occlusive and ulcerative manifestations of atherosclerotic disease.. S-EDP concentrations were measured by a competitive enzyme-linked immunosorbent assay in 10 patients with infrarenal aneurysms 5cm in diameter (AAA), 10 patients with distal aortic occlusive disease (AOD), 10 patients with symptomatic carotid stenosis (>or=70%) and plaque ulceration (SCS) and a control group of 10 patients with no similar specific manifestations of atherosclerotic disease (NAM).. S-EDP concentrations (median, range) were significantly higher in patients with AAA (42ng/ml, 35-52, p<0.001) and SCS (49ng/ml, 37-60, p<0.001) but not AOD (28ng/ml, 22-38, p=0.240) compared to NAM (26ng/ml, 19-36) patients.. Increased concentrations of S-EDP were associated with aneurysmal and ulcerative, but not occlusive, manifestations of atherosclerosis.

Topics: Aged; Aged, 80 and over; Analysis of Variance; Aortic Aneurysm, Abdominal; Aortic Diseases; Arterial Occlusive Diseases; Arteriosclerosis; Carotid Stenosis; Elastin; Enzyme-Linked Immunosorbent Assay; Female; Humans; Male; Middle Aged; Peptides; Pulmonary Disease, Chronic Obstructive; Smoking; Statistics, Nonparametric

Chronic inflammation is a characteristic feature of abdominal aortic aneurysms (AAAs), but the molecular signals responsible for recruiting monocytes into the outer aortic wall are unresolved. The purpose of this study was to examine whether AAA tissues elaborate chemotactic activity for mononuclear phagocytes and to determine whether this activity is attributable to interactions between elastin degradation peptides (EDPs) and their cell surface receptor, the 67-kD elastin binding protein (EBP).. Soluble proteins were extracted from human AAA tissues, and chemotactic activity for differentiated U937 mononuclear phagocytes was measured by use of a modified Boyden chamber. Chemotactic activity induced by N -formyl-Met-Leu-Phe was used as a positive control and checkerboard analysis was used to distinguish chemotaxis from chemokinesis. Inhibition of chemotaxis was tested by peptide competition, blocking antibodies and galactosugar-mediated dissociation of the 67-kD EBP.. AAA extracts stimulated a concentration-dependent increase in monocyte migration that reached up to 24% of the maximal effect induced by N -formyl-Met-Leu-Phe. Checkerboard analysis demonstrated that AAA extracts stimulated chemotaxis without a chemokinetic effect. AAA-derived chemotactic activity was eliminated by competition with Val-Gly-Val-Arg-Pro-Gly (VGVAPG), a repetitive peptide found in human elastin that binds to cellular elastin receptors, and decreased nearly 40% in the presence of BA-4, an antielastin monoclonal antibody that can block EDP-mediated chemotactic activity. Monocyte chemotaxis in response to both VGVAPG and AAA extracts was abolished in the presence of lactose, a galactosugar that specifically dissociates the 67-kD EBP, but it was unaffected by either glucose, fructose, or mannose.. These findings indicate that soluble EDPs released within human AAA tissue can subsequently attract mononuclear phagocytes through ligand-receptor interactions with the 67-kD EBP, thereby providing a plausible molecular mechanism to explain the inflammatory response that accompanies aneurysmal degeneration. Better understanding of factors regulating inflammatory cell recruitment may lead to novel forms of therapy for early stages of aneurysmal degeneration.

Topics: Antibodies; Aortic Aneurysm, Abdominal; Chemotaxis, Leukocyte; Elastin; Humans; Immunoglobulin G; Monocytes; N-Formylmethionine Leucyl-Phenylalanine; Oligopeptides; Receptors, Cell Surface

although the mechanism of arterial dilation and aneurysm development has not been clarified, the degradation of elastin and collagen plays undoubtedly a critical role. We evaluated the elastin and collagen content through the detection of their cross-links in aneurysmal and non-aneurysmal abdominal aortic walls.. in 26 human abdominal aortic aneurysm specimens obtained during surgery and in 24 autopsy control samples of non-aneurysmal abdominal aorta the tissue content of elastin and collagen cross-links were measured by HPLC. Collagen was also detected by evaluating two characteristic amino acids, 4-hydroxyproline (4-hypro) with a colorimetric method and 5-hydroxylysine (5-hylys) by gas chromatography.. significantly fewer elastin cross-links were found in aneurysm samples compared to controls (desmosines and isodesmosines: 90% reduction; p<0.01). The opposite was true for pyridinoline collagen cross-links (350% increase) and deoxypyridinolines (100% increase, p=0.01). Tissue content of 5-hylys, 4-hypro and total amino acids were reduced significantly by 50% in aneurysmal samples.. beside confirming decreased elastin content in aneurysmal walls, these results show a concurrent increase of collagen cross-links. Since total collagen markers were decreased (decreased 4-hypro and 5-hylys) it is reasonable to suggest that in aneurysmal aortic walls old collagen accumulates cross-links while new collagen biosynthesis is somehow defective.

Topics: Aged; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Chromatography, High Pressure Liquid; Collagen; Elastin; Female; Humans; Hydroxylysine; Hydroxyproline; In Vitro Techniques; Male; Pyridinium Compounds

abdominal aortic aneurysm (AAA) distensibility may be an independent predictor of growth and rupture, possibly because it reflects changes in aortic wall structure and composition.. to determine whether AAA distensibility is related to circulating markers of elastin and collagen metabolism.. sixty-two male patients of median age (IQR) 68 (65-72) years with asymptomatic AAA of median (IQR) diameter 42 (37-45) mm were prospectively studied. Pressure-strain elastic modulus (Ep) and stiffness (beta) were measured using an ultrasonic echo-tracker (Diamove). Serum elastin peptides (SEP), plasma elastin-alpha1-antitrypsin complex (E-AT), procollagen III-N-terminal propeptide (PIIINP) were measured by enzyme-linked immunoassay.. age and smoking adjusted Ep and beta were significantly inversely related to SEP (r=-0.33 and r=-0.31 respectively, both p<0.02) and E-AT (r=-0.27 and r=-0.27 respectively, both p<0.05) both of which indicate elastolysis. By contrast, there was a significant positive correlation between PIIINP, indicative of increased collagen turn-over, and both Ep and beta (both r=0.45, p<0.01 unadjusted correlations).. increased elastolysis is associated with increased AAA wall distensibility; whereas increased collagen turn-over is associated with reduced distensibility.

Topics: Adult; Aortic Aneurysm, Abdominal; Collagen; Elasticity; Elastin; Humans; Male; Middle Aged; Prospective Studies

small abdominal aortic aneurysms (AAAs) do rupture and only half of AAAs above 5 cm would have ruptured unoperated. Furthermore, conservative treatment of AAAs may cause psychological side effects and impaired quality of life. To optimise the indication and time for operation for AAAs, we analysed whether serum elastin peptides (EP), procollagen-IIIN-terminal propeptide (PIIINP), and the initial AAA size could predict operation for AAAs in initially conservatively treated AAA.. in 1994, 4404 65-73 year old males were invited to hospital-based screening for AAAs by ultrasonography. Seventy-six percent attended. One hundred and forty-one (4.2%) had AAAs (def: +30 mm). Nineteen were offered operation (AAA +50 mm), and 112 were followed with annual control scans for 1-5 years (mean 2.5 years). Of these, 99 had their EP (ng/ml) and PIIINP (ng/ml) determined using ELISA and RIA techniques. Two observers and one scanner were used.. the mean expansion rate was 2.7 mm/year. The initial AAA size (r =0.46; 0.26-0.61), EP ( r =0.31; 0.11-0.49), and NPIIIP ( r =0.24; 0.02-0.44) was independently significant associated to expansion rate in a multiple linear regression analysis including the three mentioned variables. The multivariate formula could by ROC curve analysis predict cases reaching 5 cm in diameter within 5 years with a sensitivity and specificity of 91% and 87%, respectively, increasing to 91% and 94%, respectively, by accepting a 2 mm variation in those measurements. Twenty-three were lost to follow up, 21 of these due to death or severe illness. Of these, seven would have been predicted to reach an AAA size recommendable for surgery. If all 23 were included in the analysis, the sensitivity and specificity would have been 87% and 85%, respectively.. a predictive model using EP, PIIINP, and initial AAA size seems capable of predicting nine out of 10 AAAs that will be operated on within 5 years. However, a larger sample size is needed for clinical recommendations.

Topics: Aged; Aortic Aneurysm, Abdominal; Cohort Studies; Collagen; Elastin; Enzyme-Linked Immunosorbent Assay; Humans; Linear Models; Male; Mass Screening; Peptides; Predictive Value of Tests; Procollagen; Protein Precursors; Radioimmunoassay; ROC Curve; Sensitivity and Specificity; Severity of Illness Index; Ultrasonography

to determine whether serum elastin-derived peptides (S-EDP), are lower in patients with ruptured abdominal aortic aneurysms (rAAA) than asymptomatic (aAAA).. serum samples were collected preoperatively from 45 consecutive patients with aAAA and 15 haemodynamically stable patients with rAAA. S-EDP (ng/ml) was measured by a competitive enzyme-linked immunosorbent assay (ELISA).. S-EDP (mean +/- s.d.) was significantly lower in patients with rAAA (31.6 ng/ml +/- 6.8) than in patients with aAAA (39.4 ng/ml +/- 8.0 p=0.001).. patients with rAAA had significantly lower levels of S-EDP than patients with aAAA. The possibility that S-EDP can be used to identify patients at increased risk of rupture requires further investigation.

Topics: Aneurysm, Ruptured; Aortic Aneurysm, Abdominal; Elastin; Humans; Peptides

Three proteolytic systems seem involved in the aneurysmal degradation of the aortic wall. Plasmin is a common activator of the systems and could thus be predictive for the progression of abdominal aortic aneurysms (AAAs).. In 1994, 112 of 141 male patients with AAA diagnosed through population screening (defined as 3 cm or more) were interviewed and examined and had blood samples taken. One hundred twelve cases were scanned annually for 1 to 5 years (mean, 2.5 years) and referred for surgery if the AAA exceeded 5 cm in diameter. A random sample of 70 of the 112 cases had P-plasmin-antiplasmin-complexes (PAPs), P-plasminogen, and S-elastin-peptides (SEPs).. PAP was positively correlated with annual expansion rate (r = 0.39, 0.16-0.56), persisting after adjustment for initial AAA size, SEP, age, and smoking. However, PAP levels did not correlate with the initial AAA size or SEP. Furthermore, PAP levels were significantly predictive for cases expanding to operation-recommendable AAA sizes. Combined with the initial AAA size, both optimal sensitivity and specificity were 82%, increasing to 95% and 96%, respectively, excluding those lost to follow-up and accepting 2 mm of interobserver variation.. The progression of AAA is correlated with the PAP level, which seems to have a predictive value similar to the best serologic predictor known, serum-elastin-peptides.

Topics: Aged; alpha-2-Antiplasmin; Antifibrinolytic Agents; Aortic Aneurysm, Abdominal; Disease Progression; Elastin; Fibrinolysin; Follow-Up Studies; Humans; Linear Models; Male; Mass Screening; Observer Variation; Patient Selection; Plasminogen; Predictive Value of Tests; ROC Curve; Severity of Illness Index; Time Factors; Ultrasonography

Serum elastin peptides (SEP) have been reported to be associated with the expansion of small abdominal aortic aneurysms (AAA). Consequently, SEP-measurements may predict future rupture, and allow further selection for surgery in cases referred for surgery due to size.. SEP was measured in 90 men and 10 women with AAA, who were considered for surgery as part of the Chichester aneurysm screening programme. Sixty-one patients were electively operated and four because of symptoms. The rest were followed up further. Twelve of these experienced ruptured AAA later.. No correlation between last measured AAA-diameter, annual expansion rate and SEP was noticed. However, SEP levels were significantly higher in cases rupturing later, persisting after adjustment for age, sex, and last measured AAA-size. ROC curve analysis concerning SEP as a predictor of rupture later showed an optimal sensitivity and specificity of 67% and 60%, respectively, similar with last measured AAA-size. By combining AAA-size and SEP, the optimal sensitivity and specificity reached 83% and 66%, respectively.. One sampling of SEP combined with AAA-size in patients referred for AAA surgery may be a clinical useful indicator of high rupture risk.

Topics: Aged; Aged, 80 and over; Aortic Aneurysm, Abdominal; Aortic Rupture; Biomarkers; Elastin; Female; Humans; Male; Peptides; Predictive Value of Tests; Preoperative Care; ROC Curve; Sensitivity and Specificity

Previous findings vary regarding the timing and cause of elastin fiber degeneration in the elastase-induced rat abdominal aortic aneurysm model. We examined the timing and cause of elastin fiber degeneration after elastase infusion using two different elastase infusion times. Twenty-four Sprague-Dawley rats were divided into two groups. The infrarenal abdominal aorta was infused with 15 U of elastase for 15 min (n = 12, 15-min infusion group) or 30 min (n = 12, 30-min infusion group). In each group, three rats were killed immediately and 1, 3, and 7 days after infusion, and then the aortas were excised for a histologic examination. Elastin fibers did not stain, even immediately after elastase infusion, in the 30-min infusion group. The degeneration of elastin fibers did not progress in the 15-min infusion group during the period of observation. Inflammatory cells infiltrated mainly to the adventitia near regions where the degeneration of elastin fibers spread totally through the aortic media. Elastin fibers degenerate immediately after elastase infusion and thus seem to degenerate not due to endogenous proteinases that are produced by the infiltrating cells, but due to the exogenously infused elastase itself. Inflammatory cell infiltration was thus found to be a result of the degeneration of elastin fibers in this model.

Topics: Animals; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elastin; Pancreatic Elastase; Rats; Rats, Sprague-Dawley

increased levels of various proteinases have been detected in abdominal aortic aneurysms (AAA) and are assumed to cause the degradation of the aortic wall. To determine whether systemic measurement of these proteinases and their inhibitors may predict the natural cause of AAA.. serum (S) and plasma (P) samples were obtained from 121 men following the diagnosis of a small AAA (3-5 cm) at population screening. Annual control scans were performed to check for expansion. Circulating levels of elastase-alpha 1 antitrypsin-complexes, alpha 1 antitrypsin, matrix metalloproteinase (MMP) 2 & 9, tissue-inhibitor-matrixproteinase 1 & 2, procollagen III-N-terminal-propeptide, and elastin-peptides were measured in a random group of 36 men.. alpha 1 antitrypsin was significantly and positively associated with expansion. Similarly, P-MMP9 levels were significantly associated with size and expansion. There was a difference between median serum and plasma values, probably because of secretion from platelets.. P-MMP9 and P-alpha 1 antitrypsin may predict the natural history of AAA.

Topics: Aged; alpha 1-Antitrypsin; Aortic Aneurysm, Abdominal; Biomarkers; Elastin; Humans; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Pancreatic Elastase; Peptide Fragments; Procollagen; Prognosis; Tissue Inhibitor of Metalloproteinase-1; Tissue Inhibitor of Metalloproteinase-2

To examine quantitative changes of elastin, fibrillin and collagen in abdominal aortic aneurysms, including ruptured abdominal aortic aneurysms (RAAA), inflammatory abdominal aortic aneurysms (IAAA) and abdominal aortic aneurysms (AAA) were measured. Items measured included the desmosine content of the aorta (desmosine 1) or of the elastin fraction (desmosine 2), fibrillin content in the aorta, hydroxyproline in the aorta, collagen percent and elastin percent, and were compared with control samples from the nonaneurysmal aortic segments. The elastin contents (desmosine 2) in RAAA, IAAA and AAA were significantly lower than those of controls. The content of the desmosine 2 from IAAA and AAA did not show a negative association with Ca. The fibrillin contents of the aorta from RAAA, IAAA and AAA were significantly higher than those of controls. The collagen content in the RAAA aorta was significantly higher than that of controls. There was a correlation of the ratio of fibrillin to elastin components (fibrillin/desmosine 1 or fibrillin/desmosine 2 or fibrillin/elastin%) and the ratio of collagen to elastin components (collagen/desmosine 1 or collagen/desmosine 2 or collagen/elastin%). These results indicated that increasing fibrillin and collagen might be a complementary result of decreasing elastin crosslinks in the aorta. This phenomenon was markedly in RAAA.

Topics: Aged; Aged, 80 and over; Aortic Aneurysm, Abdominal; Collagen; Elastin; Fibrillins; Humans; Microfilament Proteins

Loss of elastin in the aortic wall is an early event in abdominal aortic aneurysm (AAA). An imbalance in the protease-antiprotease system is proposed to be one of the factors that promote connective tissue destruction. We hypothesize that plasma from AAA patients will have a reduced inhibitory capacity in comparison to normal controls.. Using an assay we developed, plasma (10 microliters), collected from AAA patients (n = 14) and normal controls (n = 13), was added to the elastase inhibition assay containing succinylated elastin substrate. The reaction was initiated with 13.9 units porcine pancreatic elastase (PPE). Elastase activity in the presence and absence of plasma was compared. Plasma elastase was also determined using the Merck PMN-elastase kit.. The relative activity of exogenous elastase (%) in the presence of AAA plasma (n = 14, mean age 73.4 years +/- 1.7 SEM) was 42.59% +/- 4.3 SEM, while that in the presence of control plasma (n = 13, mean age 73.9 years +/- 2.1 SEM) was 10.23% +/- 2.1 SEM (P < 0.0001). Analysis of plasma elastase (microgram/L) indicated that there was no significant difference between normal (n = 9, 207.33 microgram/L +/- 58.67 SEM) and AAA (n = 9, 145.34 microgram/L +/- 29.54 SEM) (P = 0.359).. There is a significant reduction in the plasma inhibitory capacity of elastase in AAA patients in comparison to normal controls, though plasma elastase level was not significantly different. The data presented here give experimental evidence to the protease-antiprotease imbalance in AAA patient plasma and may lead to the development of a measurable parameter to monitor AAA.

Topics: Aged; Aortic Aneurysm, Abdominal; Case-Control Studies; Connective Tissue; Elastic Tissue; Elastin; Enzyme Inhibitors; Humans; Metalloendopeptidases; Pancreatic Elastase

Abdominal aortic aneurysms (AAAs) are associated with chronic inflammation, disruption of medial elastin, and increased local production of elastolytic matrix metalloproteinases (MMPs). The purpose of this study was to investigate how treatment with a hydroxamate-based MMP antagonist (RS 132908) might affect the development of experimental AAAs.. Male Wistar rats underwent intraluminal perfusion of the abdominal aorta with 50 units of porcine pancreatic elastase followed by treatment for 14 days with RS 132908 (100 mg/kg/day subcutaneously; n = 8) or with vehicle alone (n = 6). The external aortic diameter (AD) was measured in millimeters before elastase perfusion and at death, with AAA defined as an increase in AD (DeltaAD) of at least 100%. Aortic wall elastin and collagen concentrations were measured with assays for desmosine and hydroxyproline, and fixed aortic tissues were examined by light microscopy.. AAAs developed in all vehicle-treated rats, with a mean AD (+/- SE) that increased from 1.60 +/- 0.03 mm before perfusion to 5.98 +/- 1.02 mm on day 14 (DeltaAD = 276.4 +/- 67.7%). AAAs developed in only five of eight animals (62.5%) after MMP inhibition, with a mean AD that increased from 1.56 +/- 0.05 mm to 3.59 +/- 0.34 mm (DeltaAD = 128.1 +/- 18.7%; P <.05, vs vehicle). The overall inhibition of aortic dilatation attributable to RS 132908 was 53.6 +/- 6.8%. Aortic wall desmosine fell by 85.4% in the vehicle-treated rats (1210.6 +/- 87.8 pmol/sample to 176.7 +/- 33.4 pmol/sample; P <.05) but only by 65.6% in the animals treated with RS 312908 (416.2 +/- 120.5 pmol/sample). In contrast, hydroxyproline was not significantly affected by either elastase perfusion or drug treatment. Microscopic examination revealed the preservation of pericellular elastin and a greater degree of fibrocollagenous wall thickening after MMP inhibition, with no detectable difference in the extent of inflammation.. Systemic MMP inhibition suppresses aneurysmal dilatation in the elastase-induced rodent model of AAA. Consistent with its direct inhibitory effect on various MMPs, RS 132908 promotes the preservation of aortic elastin and appears to enhance a profibrotic response within the aortic wall. Hydroxamate-based MMP antagonists may therefore be useful in the development of pharmacologic approaches to the suppression of AAAs.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Collagen; Desmosine; Disease Models, Animal; Elastin; Hydroxamic Acids; Hydroxyproline; Injections, Intra-Arterial; Injections, Subcutaneous; Male; Metalloendopeptidases; Pancreatic Elastase; Pharmaceutical Vehicles; Protease Inhibitors; Rats; Rats, Wistar

Topics: Aneurysm, Infected; Aortic Aneurysm, Abdominal; Elastin; Humans

Elastolytic matrix metalloproteinases play a central role in the development of chronic atherosclerotic aortic aneurysms, but mycotic aortic aneurysms are a distinct and unusual form of aneurysm disease caused by bacterial infection. Mycotic aortic aneurysms follow a more rapid and unpredictable course than chronic aneurysm disease and they exhibit a predilection for the suprarenal aorta, further implying unique pathophysiologic mechanisms. The purpose of this study was to examine the nature and source of elastin-degrading enzymes in mycotic aortic aneurysm. Bacterial isolates and aortic tissues were obtained from four consecutive patients undergoing surgical repair of suprarenal mycotic aortic aneurysm. Using an in vitro 3H-labeled elastin degradation assay, elastin-degrading enzyme activity was only observed in the bacteria-conditioned medium from an isolate of Pseudomonas aeruginosa. Elastin-degrading enzyme activity in the aortic tissue homogenate of this patient was abolished by the serine protease inhibitor, phenylmethylsulfonyl fluoride, but it was not suppressed by the metalloproteinase inhibitor, ethylenediamine tetraacetic acid (EDTA). In contrast, elastin-degrading enzyme activity in the bacterial-conditioned medium was decreased by about half by both phenylmethylsulfonyl fluoride and EDTA. Elastin substrate zymography revealed two phenylmethylsulfonyl fluoride-inhibitable elastin-degrading enzyme activities in the aortic tissue homogenate that corresponded to human neutrophil elastase (approximately 30 kDa) and its stable complex with alpha 1-proteinase inhibitor (approximately 80 kDa), but no activity attributable to Pseudomonas elastase, a 33-kDa metal-dependent enzyme. Human neutrophil elastase was readily detected throughout mycotic aortic aneurysm tissues by immunohistochemistry, but elastolytic metalloproteinases were only occasionally observed. The results of this study suggest that the elastin-degrading enzyme produced in mycotic aortic aneurysm are largely serine proteases of host neutrophil origin, rather than elastases produced by the infecting microorganisms or the macrophage-derived metalloproteinases typically observed in atherosclerotic aneurysm disease. Further studies will be needed to extend these findings to a larger number of patients with mycotic aortic aneurysm and those caused by additional microorganisms.

Topics: Aged; Aged, 80 and over; Aneurysm, Infected; Aortic Aneurysm, Abdominal; Elastin; Female; Humans; Immunohistochemistry; Inflammation; Leukocyte Elastase; Male; Metalloendopeptidases; Serine Endopeptidases

The broad-spectrum MMP inhibitor CGS 27023A was tested to determine its potential as a therapy for atherosclerosis, aneurysm, and restenosis. LDL receptor-deficient (LDLr -/-) mice fed a high-fat, cholic acid-enriched diet for 16 weeks developed advanced aortic atherosclerosis with destruction of elastic lamina and ectasia in the media underlying complex plaques. Lesion formation correlated with a 4.6- to 21.7-fold increase in MMP-3, -12, and -13 expression. Treatment with CGS 27023A (p.o., b.i.d. at 50 mg/kg) had no effect on the extent of aortic atherosclerosis (36 +/- 4% versus 30 +/- 2% in controls), but both aortic medial elastin destruction and ectasia grade were significantly reduced (38% and 36%, respectively, p < 0.05). In the rat ballooned-carotid-artery model, CGS 27023A (12.5 mg/kg/day via osmotic minipump) reduced smooth muscle cell migration at 4 days by 83% (p < 0.001). Intimal lesions were reduced by 85% at 7 days (p < 0.001), but intimal smooth muscle proliferation was unaffected, and inhibitory efficacy was lost with time. At 12 days, intimal lesion reduction was less potent (52%, p < 0.01). At 3 and 6 weeks, reductions of 11% and 4%, respectively, were not significant. This demonstrates that it is essential to include late time points when the ballooned-carotid-artery model is employed to ensure that lesion size does not "catch up" when a compound solely inhibits smooth muscle cell migration. In summary, MMP inhibitor therapy delayed but did not prevent intimal lesions, thereby demonstrating little promise to prevent restenosis. In contrast, MMP inhibitor therapy may prove useful to retard progression of aneurysm.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Arteriosclerosis; Carotid Arteries; Carotid Artery Injuries; Catheterization; Cell Movement; Collagenases; Elastin; Hydroxamic Acids; Male; Matrix Metalloproteinase 12; Matrix Metalloproteinase 13; Matrix Metalloproteinase 3; Metalloendopeptidases; Mice; Mice, Knockout; Protease Inhibitors; Pyrazines; Rats; Rats, Sprague-Dawley; Receptors, LDL; Recurrence; Sulfonamides; Transcription, Genetic

Abdominal aortic aneurysms are characterized by degradation of the extracellular matrix, with a reduction in the elastin concentration of the arterial media. These changes have been linked to increased levels of endogenous metalloproteinases (MMPs) within the aorta, particularly MMP-2 and MMP-9. This provides a potential therapeutic target for pharmacological agents aimed at reducing the growth rate of small aneurysms. In this study, the ability of marimastat (an MMP inhibitor) to reduce matrix degradation was assessed in a previously described model of aneurysm disease.. Porcine aortic segments (n = 12) were preincubated in exogenous pancreatic elastase for 24 h before culture in standard conditions for 13 days with marimastat 10(-5), 10(-6) and 10(-7) mol/l. Control segments were cultured both without marimastat and without elastase. At the termination of culture, MMPs were extracted from the tissue and quantified by substrate gel enzymography. The volume fractions of elastin and collagen were determined by stereological analysis of sections stained with Miller's elastin and van Gieson's stain.. Stereological analysis demonstrated preservation of elastin in aorta treated with marimastat at 10(-6) and 10(-5) mol/l; this was significant at the latter concentration (P = 0.007). This was accompanied by a significant reduction in active MMP-2 activity in the samples treated with marimastat 10(-5) mol/l (P < 0.01).. Marimastat significantly inhibited elastin degradation and active MMP-2 production within aortic organ cultures.

Topics: Animals; Aortic Aneurysm, Abdominal; Cells, Cultured; Elastin; Enzyme Inhibitors; Extracellular Matrix; Gelatinases; Hydroxamic Acids; Matrix Metalloproteinase 2; Metalloendopeptidases; Swine

The relationship between abdominal aortic aneurysms (AAA) and chronical obstructive pulmonary disease (COPD), and in particular the suggested common elastin degradation caused by elastase and smoking was analysed by a cross sectional population mass screening study for AAA, and a prospective cohort study of small AAA. All previous computer-hospital-recorded diagnoses were received concerning 4,404 men invited to screening for AAA. One hundred and forty-one had AAA (4.2%). They were asked for an interview, a clinical examination, and a blood sample. Men with an AAA of 3-5 cm were offered annual control-scans to check for expansion. Of COPD-patients, 7.7% had AAA (crude OR = 2.05), however the adjusted OR was only 1.53 after adjusting for other co-existing diseases (p = 0.13). The mean annual expansion was 2.74 mm per year in COPD patients and 2.72 in non-COPD patients, and 4.7 mm in oral steroid-users compared to 2.6 in non-steroid-users (p < 0.05). S-elastin-peptides (SEP) and P-elastase-alpha1-antitrypsin-complexes (PEAC) were negatively correlated to FEV1 in COPD-patients. However, SEP, beta-agonist-treatment, and FEV1 was positively correlated to expansion by multivariate regression analysis, while PEAC and S-alpha1-antitrypsin did not influence expansion, suggesting elastase plays a major role in the pathogenesis of COPD but not in AAA. The high prevalence of AAA among patients with COPD is more likely to be caused by medication and coexisting diseases rather than a common pathway of pathogenesis.

Topics: alpha 1-Antitrypsin; Aortic Aneurysm, Abdominal; Cohort Studies; Cross-Sectional Studies; Denmark; Elastin; Forced Expiratory Volume; Humans; Lung Diseases, Obstructive; Male; Middle Aged; Prospective Studies; Smoking; Vital Capacity

To investigate (i) elastin degradation and the possible association between proteolysis and inflammation in abdominal aortic aneurysm disease (AAA), and (ii) the presence of cytomegalovirus (CMV) infection in the walls of AAA.. Specimens from 12 infrarenal AAAs, eight aortas with occlusive disease (AOD) and two normal aortas were studied by conventional light microscopy, immunohistochemistry using a monoclonal anti-elastin antibody BA-4 and anti-CMV antibody and transmission electron microscopy (TEM).. In AAA the decrease in elastin immunoreactivity and the presence of elastin degradation was associated with increased mononuclear inflammatory cell infiltrates (p = 0.004 and p = 0.00002, respectively). The CMV immunostainings of the normal aortic wall and all the AAA and AOD samples were negative, nor could any CMV particles be demonstrated by TEM.. The chronic inflammation and degradation of elastin in AAA suggests a possible immune-mediated mechanism. The inflammation may be induced by the chemotactic properties of elastin-derived peptides.

Topics: Adult; Aged; Antigens, Viral; Aortic Aneurysm, Abdominal; B-Lymphocytes; Chronic Disease; Cytomegalovirus Infections; Elastin; Female; Humans; Immunohistochemistry; Immunophenotyping; Inflammation; Macrophages; Male; Microscopy, Electron; Middle Aged; T-Lymphocytes

Although matrix metalloproteinases (MMPs) are expressed in abundance in arterial aneurysms, their contribution to arterial wall degeneration, dilation, and rupture has not been determined. We investigated MMP function in a rat model of aneurysm associated with arterial dilation, elastin loss, medial invasion by mononuclear inflammatory cells, and MMP upregulation. Rupture was correlated with increased gelatinase B (MMP-9) and activated gelatinase A (MMP-2). Syngeneic rat smooth muscle cells retrovirally transfected with tissue inhibitor of matrix metalloproteinases (TIMP)-1 cDNA (LTSN) or with the vector alone as a control (LXSN) were seeded onto the luminal surface of the vessels. The seeding of LTSN cells resulted in TIMP-1 local overexpression. The seeding with LTSN cells, but not LXSN cells, decreased MMP-9, activated MMP-2 and 28-kD caseinase and elastase activity, preserved elastin in the media, and prevented aneurysmal degeneration and rupture. We conclude that MMP overexpression is responsible for aneurysmal degeneration and rupture in this rat model and that local pharmacological blockade might be a reasonable strategy for controlling the formation of aneurysms in humans.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Rupture; Collagenases; Desmosine; Elastin; Gelatinases; Guinea Pigs; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Metalloendopeptidases; Muscle, Smooth, Vascular; Rats; Rats, Inbred F344; Recombinant Proteins; Tissue Inhibitor of Metalloproteinase-1; Tissue Inhibitor of Metalloproteinase-2; Tissue Inhibitor of Metalloproteinase-3; Transfection; Transplantation, Heterologous

Elastolytic matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of abdominal aortic aneurysms (AAA), a disorder characterized by chronic aortic wall inflammation and destruction of medial elastin. The purpose of this study was to determine if human macrophage elastase (HME; MMP-12) might participate in this disease. By reverse transcription-polymerase chain reaction, HME mRNA was consistently demonstrated in AAA and atherosclerotic occlusive disease (AOD) tissues (six of six), but in only one of six normal aortas. Immunoreactive proteins corresponding to proHME and two products of extracellular processing were present in seven of seven AAA tissue extracts. Total HME recovered from AAA tissue was sevenfold greater than normal aorta (P < 0.001), and the extracted enzyme exhibited activity in vitro. Production of HME was demonstrated in the media of AAA tissues by in situ hybridization and immunohistochemistry, but HME was not detected within the media of normal or AOD specimens. Importantly, immunoreactive HME was specifically localized to residual elastin fragments within the media of AAA tissue, particularly areas adjacent to nondilated normal aorta. In vitro, the fraction of MMP-12 sequestered by insoluble elastin was two- to fivefold greater than other elastases found in AAA tissue. Therefore, HME is prominently expressed by aneurysm-infiltrating macrophages within the degenerating aortic media of AAA, where it is also bound to residual elastic fiber fragments. Because elastin represents a critical component of aortic wall structure and a matrix substrate for metalloelastases, HME may have a direct and singular role in the pathogenesis of aortic aneurysms.

Topics: Aortic Aneurysm, Abdominal; Aortic Diseases; Arteriosclerosis; Elastin; Enzyme Induction; Enzyme Precursors; Humans; In Situ Hybridization; Macrophages; Matrix Metalloproteinase 12; Metalloendopeptidases; Reverse Transcriptase Polymerase Chain Reaction; Tunica Media

Abdominal aortic aneurysms (AAAs) are characterized by structural deterioration of the aortic wall leading to progressive aortic dilatation and eventual rupture. The histopathological changes in AAAs are particularly evident within the elastic media, which is normally dominated by vascular smooth muscle cells (SMCs). To determine whether a decrease in vascular SMCs contributes to medial degeneration, we measured SMC density in 21 normal and pathological human abdominal aortic tissue specimens using immunohistochemistry for alpha-SMC actin and direct cell counts (medial SMCs per high-power field (HPF)). Medial SMC density was not significantly different between normal aorta (n = 5; 199.5 +/- 14.9 SMCs/HPF) and atherosclerotic occlusive disease (n = 6; 176.4 +/- 13.9 SMCs/HPF), but it was reduced by 74% in AAA (n = 10; 50.9 +/- 6.1 SMCs/HPF; P < 0.01 versus normal aorta). Light and electron microscopy revealed no evidence of overt cellular necrosis, but SMCs in AAAs exhibited ultrastructural changes consistent with apoptosis. Using in situ end-labeling (ISEL) of fragmented DNA to detect apoptotic cells, up to 30% of aortic wall cells were ISEL positive in AAAs. By double-labeling techniques, many of these cells were alpha-actin-positive SMCs distributed throughout the degenerative media. In contrast, ISEL-positive cells were observed only within the intimal plaque in atherosclerotic occlusive disease. The amount of p53 protein detected by immunoblotting was increased nearly fourfold in AAA compared with normal aorta and atherosclerotic occlusive disease (P < 0.01), and immunoreactive p53 was localized to lymphocytes and residual SMCs in the aneurysm wall. Using reverse transcription polymerase chain reaction assays a substantial amount of p53 mRNA expression was observed in AAAs. These results demonstrate that medial SMC density is significantly decreased in human AAA tissues associated with evidence of SMC apoptosis and increased production of p53, a potential mediator of cell cycle arrest and programmed cell death. Given the role that SMCs normally play in maintaining medial architecture and in arterial wall matrix remodeling, the induction of SMC apoptosis likely makes an important contribution to the evolution of aneurysm degeneration.

Topics: Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apoptosis; Cell Count; Cell Nucleus; Collagen; DNA Fragmentation; Elastin; Extracellular Matrix; Genes, p53; Humans; Immunohistochemistry; Microscopy, Electron; Muscle, Smooth, Vascular; RNA, Messenger; Tumor Suppressor Protein p53; Tunica Media

Infusion of the abdominal aorta with pancreatic elastase induces aneurysms in a rat model (Anidjar/Dobrin). Because elastolysis liberates elastin degradation products (EDPs), the present experiment was carried out to test the hypothesis that an EDP alone could induce features of aneurysm disease.. The EDP val/gly/val/ala/pro/gly (VGVAPG), elastase, or saline solution was infused into infrarenal aorta (n = 4/group). After 1 week aortic diameters were measured, and the tissues were prepared for histologic examination. Adventitial capillaries (vessels per high-power field) were counted over a standardized preparation of aorta. Wall thickness was measured by means of computer-aided planimetry.. There was an increase of greater than 100-fold in mean vessels per high-power field in aortas receiving VGVAPG or elastase versus saline controls (4.10 +/- 0.68 SEM or 4.48 +/- 0.49 SEM versus 0.03 +/- 0.03 SEM, respectively, p < 0.05). The VGVAPG-perfused group had a 26% +/- 4% SEM increase in diameter from baseline that was statistically significant (p < 0.01), but the aortas did not reach aneurysmal dimensions.. Although no aneurysms occurred at 1 week after the infusion of EDP, the results demonstrate that the EDP VGVAPG can induce a characteristic feature of aneurysm disease. The model permits study of the earliest stages of experimental aneurysm formation and raises interesting questions regarding the role of the vasa vasorum in this pathologic process.

Topics: Animals; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elastin; Muscle, Smooth, Vascular; Neovascularization, Pathologic; Oligopeptides; Rats; Rats, Wistar

To optimise the indication and time for operation for abdominal aortic aneurysm (AAA), we analysed whether or not serum-elastin-peptides (SEP) could be a potential predictor for expansion.. Four thousand, four hundred and four 65-73-year-old males were invited for screening to detect an AAA. Three thousand, three hundred and thirty-four attended (76%). One hundred and forty-one had AAA, and 19 > 5 cm in diameter were referred for immediate operation. The remaining 122 AAA were offered an annual follow-up. Ninety-nine were later asked for a blood-sample, 83 attended. SEP was determined using an ELISA-technique. The observer was blinded to the SEP result.. The average expansion was 2.6 mm/year, and 10 (8.1) were referred for operation because of a diameter of > 5 cm. SEP were positively correlated to expansion (R = 0.4, F = 14.65). In multiple regression analyses, AAA size, SEP, beta-agonist-treatment, and FEV1, but not beta-blockers, were predictors of expansion. SEP remained a relatively strong predictor (F = 13.13).. Serum-elastin-peptides seem to predict expansion, but a larger, longer study is needed to establish clinical recommendations.

Topics: Aged; Aortic Aneurysm, Abdominal; Elastin; Humans; Linear Models; Male; Peptides; Predictive Value of Tests; Severity of Illness Index

The molecular mechanisms predisposing to atherosclerotic aneurysm formation remain undefined. Nevertheless, rupture of aortic aneurysms is a major cause of death in Western societies, with few available treatments and poor long-term prognosis. Indirect evidence suggests that matrix metalloproteinases (MMPs) and plasminogen activators (PAs) are involved in its pathogenesis. MMPs are secreted as inactive zymogens (pro-MMPs), requiring activation in the extracellular compartment. Plasmin, generated from the zymogen plasminogen by tissue-type plasminogen activator (t-PA) or urokinase-type plasminogen activator (u-PA; refs 14,15), has been proposed as a possible activator in vitro, but evidence for such a role in vivo is lacking. Analysis of atherosclerotic aorta in mice with a deficiency of apoliprotein E (Apoe-/-; ref. 18), singly or combined with a deficiency of t-PA (Apoe-/-:Plat-/-) or of u-PA (Apoe-/-:Plau-/-; ref. 19), indicated that deficiency of u-PA protected against media destruction and aneurysm formation, probably by means of reduced plasmin-dependent activation of pro-MMPs. This genetic evidence suggests that plasmin is a pathophysiologically significant activator of pro-MMPs in vivo and may have implications for the design of therapeutic strategies to prevent aortic-wall destruction by controlling Plau gene function.

Topics: Animals; Aortic Aneurysm, Abdominal; Aortic Aneurysm, Thoracic; Arteriosclerosis; Collagen; Diet, Atherogenic; Elastin; Enzyme Activation; Female; Fibrinolysin; Macrophages; Male; Metalloendopeptidases; Mice; Mice, Knockout; Tunica Media; Urokinase-Type Plasminogen Activator

Aneurysms are morphologically classified as true or false based on the nature of their walls. True aneurysms are composed of all or parts of layers of the vessel. False aneurysms are the result of rupture and their walls have only fibrous tissues. The orifice of false aneurysms is narrow relative to the aneurysmal diameter and thus they are grossly or angiographically referred to as punched-out lesions. Hence false aneurysms present with punched-out lesions, but in reverse, are all of punched-out lesions false aneurysms? We experienced some cases of punched-out lesions which histologically contained traces of elastin, and the purpose of this report was to histologically investigate grossly punched-out lesions. We examined 671 elderly autopsy cases, and a total of 21 grossly punched-out lesions in the aorto-iliac region were selected. They were histologically classified as false, "pseudo-false", or "disguised" aneurysm. False aneurysms were found in 3 patients (0.45%), and were histologically mycotic. A total of 5 "pseudo-false" aneurysms were found in 3 patients (0.45%). They histologically contained traces of elastin, and thus they were categorised in true aneurysms. A total of 13 "disguised" aneurysms were found in 6 patients (0.89%). They were true fusiform aneurysms with an eccentric thrombus, on which a fibrin-cap formed a narrow orifice. Partial sections are insufficient for diagnosis; cross-sections are necessary. To the best of our knowledge, there have been no reports of "pseudo-false" or "disguised" aneurysms in the aorto-iliac region.

Topics: Aged; Aged, 80 and over; Aneurysm, False; Aneurysm, Infected; Aneurysm, Ruptured; Aortic Aneurysm, Abdominal; Elastin; Female; Humans; Iliac Aneurysm; Immunohistochemistry; Male; Retrospective Studies; Rupture, Spontaneous

The relationship between atherosclerosis and abdominal aortic aneurysm development is well known. Atherosclerosis cannot explain the whole mechanism. Genetic characters of mechanisms leading to abdominal aortic development is obvious from this study and others. Our study evidences an increased metalloproteases activity in aortic wall proportionally to the size of the abdominal aortic aneurysm. A decrease of aortic wall elastin is evidenced proportionally to the AAA size. Extractable collagen is significantly increased in the aortic wall of patients operated on for aortic rupture.

Topics: Age Factors; Aged; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Rupture; Arteriosclerosis; Elastin; Female; Humans; Male; Metalloendopeptidases; Middle Aged

Increased local production of matrix metalloproteinases (MMPs) is a potential mechanism underlying structural protein degradation in abdominal aortic aneurysms (AAA). With an elastase-induced rodent model of AAA, we determined whether pharmacologic treatment with an MMP-inhibiting tetracycline might limit the development of experimental AAA in vivo.. Forty-eight Wistar rats underwent a 2-hour perfusion of the abdominal aorta with 50 U porcine pancreatic elastase and were then treated with either subcutaneous doxycycline (25 mg/day; n=24) or saline solution vehicle (n=24). Aortic diameter was measured before and after elastase perfusion was performed and before the rats were killed at 0, 2, 7, or 14 days, and AAAs were defined as an increase in aortic diameter to at least twice that before perfusion. At death the aortic tissues were either perfusion-fixed for histologic evaluation or extracted for substrate zymographic evaluation.. Aortic diameter was not different between groups at 0 or 2 days, but it was significantly less in animals treated with doxycycline at both 7 and 14 days (mean+/-SEM, p<0.01). After day 2 the incidence of AAA was reduced from 83% (10 of 12 rats treated with saline solution) to 8% (1 of 12 animals treated with doxycycline). By histologic assessment doxycycline prevented the structural deterioration of aortic elastin without decreasing the influx of inflammatory cells. Increased aortic wall production of 92 kD gelatinase observed in a saline solution-treated control group was markedly suppressed in animals treated with doxycycline.. Treatment with an MMP-inhibiting tetracycline inhibits the development of experimental AAA in vivo. This inhibition may be due to selective blockade of elastolytic MMP expression in infiltrating inflammatory cells. Additional experiments, however, are necessitated to fully delineate this process.

Topics: Animals; Anti-Bacterial Agents; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Disease Models, Animal; Disease Progression; Doxycycline; Elastin; Enzyme Inhibitors; Gelatinases; Injections, Subcutaneous; Male; Pancreatic Elastase; Rats; Rats, Wistar; Sodium Chloride; Swine

Topics: Animals; Aortic Aneurysm, Abdominal; Disease Models, Animal; Elastin; Neovascularization, Pathologic; Oligopeptides; Rats; Rats, Wistar; Vasa Vasorum

Topics: Aorta; Aortic Aneurysm, Abdominal; Elastin; Humans; Neovascularization, Pathologic; Nitric Oxide; Nitric Oxide Synthase; Nitrites

The purpose of this study was to characterize the distribution of aortic wall microvessels in normal aorta, atheroocclusive disease (AOD), and abdominal aortic aneurysms (AAA) and to evaluate whether medial neovascularization (MNV) is a reliable histopathologic marker of aneurysmal degeneration.. Aortic tissue specimens (9 normal, 10 AOD, and 10 AAA) were examined for elastin with Verhoeff-van Gieson stain and for Ulex europaeus type I lectin, an endothelial-specific antigen, and laminin, a marker of basement membranes, by immunohistochemistry. The density of MNV was determined by morphometry of aortic sections stained for endothelium. The spatial distribution of aortic microvessels was compared with that of elastin destruction and chronic inflammation.. Evidence of medial neovascularization was generally not observed in normal aorta or AOD, whereas AAAs showed strong spatial correlations between MNV, disruption and degradation of elastin, and chronic inflammation in the outer aortic wall. Several specimens of AOD had focal areas of MNV associated with localized elastin fragmentation and monocytic infiltration located at the interface between the atherosclerotic plaque and the inner media. The density of MNV was about fifteenfold higher in AAA compared with normal aorta and about threefold higher compared with AOD (microvessels per high-power field): normal aorta, 0.77 +/- 0.28; AOD, 3.40 +/- 0.51; AAA, 11.32 +/- 1.58 (ANOVA, p < 0.001).. The presence and density of MNV in the abdominal aorta is a consistent histopathologic marker of aneurysmal degeneration that is spatially correlated with the destruction of elastin and chronic inflammation. The observation of focal MNV in some specimens of AOD, associated with partial elastin disruption, raises the possibility that early changes of aneurysm disease might develop by an extension of angiogenic/inflammatory processes from the atherosclerotic plaque into the aortic media.

Topics: Adult; Aged; Analysis of Variance; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Arterial Occlusive Diseases; Arteriosclerosis; Elastin; Endothelium, Vascular; Female; Humans; Immunohistochemistry; Laminin; Lectins; Male; Middle Aged; Neovascularization, Pathologic; Tunica Media

The maintenance of the mechanical properties of the vessels results from the correct arrangement of smooth muscle cells and extracellular fibrous proteins (elastin and collagen) in their wall. The morphology of extracellular matrix modifications, particularly of elastin, was investigated in inflammatory (IA) and non specific (NSA) abdominal aortic aneurysms by scanning (SEM), transmission (TEM) and immunoelectron microscopy. Both NSAs and IAs were significantly characterized by extensive extracellular matrix remodelling, including different patterns of elastin degradation. Elastic and collagen fibres distribution appeared to be extensively altered in IAs, while it conformed more to a normal pattern in NSAs. With respect to NSAs, the morphology of elastic fibres in IAs was modified to such an extent that their identification by TEM had a rely on immunocytochemical methods and by SEM on back-scattered electron analysis. The observed ultrastructural changes are indicative of the central role of extracellular matrix modifications in the pathogenesis of IAs and NSAs.

Topics: Aortic Aneurysm, Abdominal; Elastin; Extracellular Matrix; Humans; Immunohistochemistry; Inflammation; Microscopy, Electron, Scanning; Muscle, Smooth, Vascular

Abdominal aortic aneurysms (AAAs) have traditionally been attributed to atherosclerosis, although there is increasing epidemiological, biochemical and genetic evidence that aneurysmal arterial disease is different from occlusive atherosclerosis. One of the most consistent biochemical findings in the aneurysmal aorta is a significant reduction in elastin protein; the cause, for this remains unclear. There is in vitro evidence that vitamin D3 (1,25 dihydrocholecalciferol) inhibits the production of elastin by smooth muscle cells. On the basis of this observation and the possibility that some subjects may be exposed to excess vitamin D3, the hypothesis that vitamin D3 may be a previously unrecognized aetiological factor in the pathogenesis of AAA is developed.

Topics: Aorta, Abdominal; Aortic Aneurysm, Abdominal; Cholecalciferol; Elastin; Humans; Infant; Infant, Newborn; Models, Cardiovascular

The walls of human abdominal aortas and atherosclerosis-induced aneurysms contain similar amounts of collagen. The quantitative ratio between collagens of various types of this protein does not differ significantly either, whereas solubility of the collagen in aneurysmal wall and its susceptibility to the action of EDTA are distinctly decreased. In contrast with collagen, the amount of elastin in aneurysms is significantly lower. Total amount of glycosaminoglycans slightly decreased as compared with that of normal tissue, but the ratio of particular compounds varies. The percentage of chondroitin sulphate is increased and that of heparan sulphate significantly decreased. The significance of these changes in pathogenesis of aneurysms is discussed.

Topics: Adult; Aged; Aging; Aortic Aneurysm, Abdominal; Arteriosclerosis; Case-Control Studies; Chondroitin Sulfates; Collagen; Elastin; Female; Glycosaminoglycans; Humans; Keratan Sulfate; Male; Middle Aged; Solubility

An antibody to elastin-derived chemotactic peptide Val-Gly-Val-Ala-Pro-Gly was used to study human artery samples from 18 patients with various vascular lesions, such as aneurysms or occlusive arteriopathy. The antibody recognised epitopes in two artery specimens, one occlusive arteriopathy and one aneurysm, and both specimens were also characterised by a segmental destruction of media. The positive staining for the peptide was located in the elastic membranes and endothelial cells that were also stained with antibodies to IgG. This study suggests that elastin-derived chemotactic peptides may have a role in vascular lesions characterised by a destruction of media and a formation of aneurysm. Since elastin-derived chemotactic peptides are more chemotactic to monocytes than to neutrophils, it is possible that mononuclear phagocytes are involved in the segmental destruction of elastin.

Topics: Adult; Aged; Aortic Aneurysm, Abdominal; Aortic Dissection; Arterial Occlusive Diseases; Arteries; Arteriosclerosis; Arteritis; Chemotactic Factors; Elastic Tissue; Elastin; Endothelium, Vascular; Female; Humans; Immunoenzyme Techniques; Male; Middle Aged; Peptides; Tunica Media; Vascular Diseases

The decrease in elastin concentration in abdominal aortic aneurysm (AAA) has been ascribed to elastolysis. The discordant response of the elastin and collagen genes in AAA suggests a different explanation: dilution of elastin because of higher levels of synthesis of collagen and other matrix proteins. The purpose of this study was to determine circumferential content of elastin, collagen, and total protein in aneurysmal (AAA), atherosclerotic, and normal (NL) infrarenal aorta. Standard serial extraction techniques of complete 1-cm rings of midinfrarenal aortic tissue were used to remove soluble protein, calcium, and lipids. Hydroxyproline (collagen), desmosine/isodesmosine (elastin), and total amino acid (total protein) content were determined by amino acid analysis. Means values (+/- SEM) were compared by ANOVA. Circumferential content of desmosine/isodesmosine was increased 2.5-fold in AAA compared to NL (P < 0.05). Collagen and total protein were increased 5.7- and 4.7-fold, respectively (P < 0.05). There was a high degree of correlation between circumference and collagen content (r = 0.89). These data demonstrate that significant synthesis of matrix proteins accompanies aortic dilatation. While both elastin and collagen are increased, there is a much greater increase in circumferential collagen content than elastin content. These data do not preclude proteolysis as a factor in AAA but suggest that the decrease in elastin concentration results from dilution of elastin by a greater increase in the synthesis of other matrix proteins and that synthesis is an important factor in AAA formation.

Topics: Adult; Aged; Aged, 80 and over; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Collagen; Elastin; Female; Humans; Male; Middle Aged; Proteins

Abdominal aortic aneurysms are characterized by an accelerated turnover of extracellular matrix proteins and by an inflammatory infiltrate that releases the cytokines interleukin-1 beta and tumor necrosis factor-alpha. We examined the gene expression of human aneurysmal aortic smooth muscle cells and normal aortic smooth muscle cells after treatment with interleukin-1 beta and tumor necrosis factor-alpha by measuring the changes in smooth muscle cell collagen, elastin, collagenase, and tissue inhibitor of metalloproteinase messenger ribonucleic acid levels in response to these cytokines.. Biopsy of aneurysmal aorta (n = 6) and donor normal aorta (n = 3) was obtained at operation. Medial smooth muscle cells were cultured, passaged (P2 to P4), and incubated with 0, 10, 100, or 1000 pg/ml interleukin-1 beta, tumor necrosis factor-alpha, or platelet-derived growth factor for 24 hours. Total ribonucleic acid was harvested. Percentage changes in messenger ribonucleic acid from control levels for type I and type III procollagen, elastin, collagenase, 72 kDa type IV collagenase, tissue inhibitor of metalloproteinase-1, and tissue inhibitor of metalloproteinase-2 were measured by Northern hybridization. Analyses were performed with analysis of variance (p < 0.05). All comparisons between aneurysmal aortic smooth muscle cells and normal aortic smooth muscle cells represent comparisons between one aneurysmal aorta and one normal aorta.. Added interleukin-1 beta resulted in significant, dose-dependent increases in the collagenase messenger ribonucleic acid level at all concentrations tested in both aneurysmal aorta and normal aorta. The increase in the collagenase messenger ribonucleic acid level ranged from a minimum increase of 123% for 10 pg/ml interleukin-1 beta in aneurysmal aortic smooth muscle cells to a maximum of 450% for 1000 pg/ml interleukin-1 beta in normal aortic smooth muscle cells. Interleukin-1 beta caused a significant decrease in the steady-state messenger ribonucleic acid levels for type 1 procollagen in both aneurysmal and normal aorta. The greatest reduction in type 1 procollagen messenger ribonucleic acid levels occurred at 100 pg/ml interleukin-1 beta in both aneurysmal aortic smooth muscle cells (-39%) and normal aortic smooth muscle cells (-48%). The only observed qualitative difference between aneurysmal aortic smooth muscle cells and normal aortic smooth muscle cells was the change in tissue inhibitor of metalloproteinase-1 messenger ribonucleic acid levels in response to added interleukin-1 beta. In aneurysmal aortic smooth muscle cells interleukin-1 beta at 1000 pg/ml significantly increased messenger ribonucleic acid levels by 82%, whereas levels of tissue inhibitor of metalloproteinase-1 messenger ribonucleic acid in normal aortic smooth muscle cells did not change in response to added interleukin-1 beta. Interleukin-1 beta did not alter messenger ribonucleic acid levels for type III procollagen, elastin, type IV collagenase, or tissue inhibitor of metalloproteinase-2 in aneurysmal aorta or normal aorta. When tumor necrosis factor-alpha or platelet-derived growth factor were added, this did not significantly change aneurysmal aortic smooth muscle cells messenger ribonucleic acid levels for collagenase, type IV collagenase, tissue inhibitor of metalloproteinase-1, tissue inhibitor of metalloproteinase-2, and type I and type III procollagen.. These findings suggest that interleukin-1 beta, through its effect on smooth muscle cell collagenase and collagen gene expression, mediates the increased matrix turnover observed in aneurysms. Macrophages may induce changes in aortic smooth muscle cell gene expression in a paracrine manner that could lead to aneurysm formation.

Topics: Aged; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Collagen; Collagenases; Culture Techniques; Dose-Response Relationship, Drug; Elastin; Gelatinases; Gene Expression Regulation; Genes; Glycoproteins; Humans; Interleukin-1; Matrix Metalloproteinase 1; Matrix Metalloproteinase 2; Matrix Metalloproteinase Inhibitors; Metalloendopeptidases; Middle Aged; Muscle, Smooth, Vascular; Platelet-Derived Growth Factor; Proteins; RNA, Messenger; Tissue Inhibitor of Metalloproteinase-2; Tissue Inhibitor of Metalloproteinases; Tumor Necrosis Factor-alpha

The composition and mechanical properties of abdominal aortic aneurysms (AAAs) were studied.. Stereologic study was used to measure volume fractions of the components of the aortic wall. Histochemical methods with picrosirus red and safranin O were developed to differentiate collagen from ground substance because they are difficult to distinguish from each other on histologic sections. Uniaxial tensile stress tests were carried out on a tensile-testing machine, and a stress-strain curve was plotted for each sample to study the mechanical properties of AAAs. The curves were fitted exponentially so sigma = aeb epsilon, where sigma is stress, epsilon is strain, and a and b are parameters.. In aneurysms (n = 8) the volume fraction of elastin was decreased from 22.7% +/- 5.7% to 2.4% +/- 2.2%, and the volume fraction of smooth muscle cells was decreased from 22.6% +/- 5.5% to 2.2% +/- 2.0%, whereas the volume fraction of collagen and ground substance combined was increased from 54.8% +/- 4.5% to 95.6% +/- 2.5% compared with nonaneurysmal aortas (n = 8). There was no significant difference (p > 0.05) in the ratio of collagen to ground substance (2.1 +/- 0.5 vs 2.0 +/- 0.4) between AAAs and nonaneurysmal aortas. The elastic diagrams showed that AAAs (n = 7) are less distensible and stiffer than nonaneurysmal aortas (n = 5). Parameter a was unchanged (p > 0.5), but parameter b was significantly greater (p < 0.002) for aneurysmal aortas.. Both the composition and mechanical properties of AAAs are different from those of nonaneurysmal aortas. The aneurysms were stiffer, and the volume fractions of collagen and ground substance were increased, whereas the volume fractions of elastin and muscle were decreased in aneurysms.

Topics: Aged; Aged, 80 and over; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Collagen; Elasticity; Elastin; Humans; Middle Aged; Muscle, Smooth, Vascular; Stress, Mechanical; Tensile Strength

Chronic rejection of arterial allografts and xenografts results in arterial wall dilation and rupture, making them unsuitable for long-term arterial replacement in vascular surgery. In the arterial wall, as in other organs, the cells probably carry major antigenic determinants. Arterial wall cellular components can be removed by detergent treatment to produce a graftable matrix tube.. We compared the patency and macroscopic and microscopic morphologic changes that occurred in sodium dodecyl sulfate (SDS)-treated and untreated arterial isografts, allografts, and xenografts 2 months after implantation in rats. We quantified elastin, collagen, and nuclear density in the three layers of the graft wall (intima, media, and adventitia) by morphometric methods. The SDS treatment removed endothelial and smooth muscle cells and cells in the adventitia but preserved elastin and collagen extracellular matrix.. All arterial xenografts, whether SDS treated or untreated, were aneurysmal 2 months after grafting, with loss of the medial cellular and extracellular components. In allografts, SDS treatment prevented dilation, reduced adventitial inflammatory infiltration, and preserved medial elastin. The SDS-treated allografts had an evenly distributed, noninflammatory intimal thickening that was richer in elastin fibers than that in untreated allografts.. These results suggest an interspecies, but not an intraspecies, graft antigenicity of arterial extracellular matrix. The SDS treatment prevented chronic rejection of the arterial allograft and led to the proliferation of an elastin-rich and adapted intima.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Cell Nucleus; Cell-Free System; Collagen; Detergents; Elastic Tissue; Elastin; Graft Rejection; Guinea Pigs; Male; Rats; Rats, Inbred Lew; Sodium Dodecyl Sulfate; Thrombosis; Tissue Preservation; Transplantation, Heterologous; Transplantation, Homologous; Transplantation, Isogeneic; Tunica Intima; Tunica Media; Vascular Patency

Abdominal aortic aneurysms (AAA) are associated with diffuse arteriomegaly and peripheral aneurysms, suggesting a generalized process. Elastin and collagen are the key structural proteins of the aorta, and their relative content is markedly altered in tissue from AAA. Our purpose was to investigate elastin and collagen content in the proximal, nonaneurysmal segments of aortas with infrarenal AAA.. After extraction of lipid, calcium, and soluble proteins, hydroxyproline (collagen) and desmosine-isodesmosine (elastin) contents were determined by high-performance liquid chromatography in the ascending and descending thoracic, supraceliac, and suprarenal aorta. By repeated measures of analysis of covariance, collagen was found to be increased throughout the aorta in AAA as compared with normal aorta or aorta with atherosclerotic occlusive disease. This difference remained significant when adjustments were made for group differences in age and degree of atherosclerosis. This increase in collagen content results in a dilutional decrease in elastin concentration. These data demonstrate that the same matrix protein alterations found in AAA tissue occur throughout the aorta, differing only in magnitude in the aneurysmal and nonaneurysmal segments. These data suggest that aneurysm formation may related to alterations in the regulation of elastin and collagen.

Topics: Adult; Aged; Analysis of Variance; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Arteriosclerosis; Chromatography, High Pressure Liquid; Collagen; Elastin; Extracellular Matrix Proteins; Female; Humans; Linear Models; Male

Studies of the connective tissue matrix of abdominal aortic aneurysms (AAAs) have yielded conflicting results, and the glycosaminoglycan content has not been previously reported. The present work was done to evaluate the matrix components of AAAs, including the cross-link content of the residual elastin.. Aortic specimens from AAAs and controls were sequentially extracted with salt, Brij, and urea; and the residual pellets were the subject of further studies. Elastin was purified by hot alkali treatment; other matrix components were determined by conventional methods.. Elastin content of the purified material was reduced in AAA. The cross-link content, desmosine+isodesmosine, was also reduced in AAA as a ratio to insoluble matrix dry weight. However, the cross-link content as a ratio to valine in the purified elastin was normal. The amino acid profiles of representative AAA and controls elastin preparations were similar to that of reference elastin. The amino acid content of the insoluble matrix of AAA revealed a significant reduction of protein (controls = 820 +/- 40 micrograms/mg versus AAA = 700 +/- 20 micrograms/mg, p < 0.05); the collagen content was unaltered. The content of glycosaminoglycan in AAA was noted to be significantly reduced (controls = 33.5 +/- 3.4 micrograms/mg versus AAA = 17.1 +/- 2.0 micrograms/mg, p < 0.05).. The data do not support the hypothesis of a primary cross-link deficiency in elastin of AAA; but the reduced contents of protein and glycosaminoglycans in AAA suggests basic biochemical alterations in the diseased aorta that warrant further investigation.

Topics: Amino Acids; Aortic Aneurysm, Abdominal; Collagen; Connective Tissue; Elastin; Glycosaminoglycans; Humans

The natural history and the factors determining the expansion of aneurysms have not been elucidated. To study the respective roles of elastolysis, collagenolysis, inflammatory cells, and hypertension in the pathogenesis of aneurysms, two previously described in vivo experimental models were used. An isolated segment of the abdominal aorta was infused with 15 units of pancreatic elastase. The maximal diameter of the aorta was measured before and after infusion and the isolated aorta was excised for classic histologic and immunohistologic studies. Twelve hours after the infusion of elastase the mean diameter of the aorta increased by 30%. The aorta had a cylindric form and only collagen fibers remained. Two and a half days after the infusion the aorta was spherical in shape and the diameter increased by 300% (3.09 +/- 0.08 mm) (p < 0.05). The entire aortic wall was invested by inflammatory cells. Six days after infusion the diameter increased by 421% (4.38 +/- 0.03 mm) (p < 0.05), and immunohistochemical staining showed numerous T lymphocytes and macrophages. Between 6 and 12 days, after perfusion inflammation decreased, the final diameter was 4.23 +/- 0.14 mm (not significant). Sixteen rats had thioglycollate and plasmin infusion, which are nonspecific activators of inflammation. Nine days after infusion the diameter of the aorta had increased by 288%; the elastic fibers of the media were fragmented and rare and the entire aortic wall was invaded by inflammatory cells, predominantly macrophages. The diameter of the aorta increased progressively. Two groups of 17 hypertensive rats (renovascular and spontaneous hypertension) received an aortic infusion of 15 units of pancreatic elastase. Elastolysis overlapped the limits of the infusion and inflammation persisted after 2 weeks. The mean diameter of the aorta (F = 11, p < 0.01) and the mean length of the aneurysms (F = 11.2, p < 0.001) were significantly increased. This study demonstrates that elastolysis and especially collagenolysis are determinants of aneurysmal expansion. Inflammation may be a promoting factor in the degradation of the aortic wall. Hypertension increases the hemodynamic stress to the aorta and activates mural inflammation.

Topics: Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Collagen; Elastin; Fibrinolysin; Hypertension; Inflammation; Male; Pancreatic Elastase; Rats; Rats, Wistar; Thioglycolates

Elastase release by neutrophils has been implicated in the etiology of abdominal aortic aneurysm (AAA). The present study investigated whether neutrophils in patients with AAA actively synthesize the neutrophil elastase enzyme and the effect of elastin-derived peptides on neutrophil elastase release. Total neutrophil elastase in patients with AAA was significantly higher than in those with aortic occlusive disease and controls. The neutrophil elastase gene was not expressed in any patient group. Elastin-derived peptides induced elastase release, which was significantly higher in patients with AAA than in those with aortic occlusive disease and controls. These data indicate that the peptides of elastin degradation stimulate the release of elastase, but that continuing production of elastase is absent in circulating neutrophils. It is concluded that: (1) neutrophils do not actively synthesize elastase but act as 'mules' or carriers of the enzyme; and (2) elastin breakdown products stimulate the release of elastase at the aortic wall by circulating neutrophils, which in patients with AAA have a predetermined increased amount of elastase.

Topics: Aorta, Abdominal; Aortic Aneurysm, Abdominal; Chemotaxis, Leukocyte; Elastin; Humans; Leukocyte Count; Neutrophils; Pancreatic Elastase; Peptides

Collagen and elastin are the main extracellular matrix proteins providing the aortic wall with adequate mechanical properties and resistance for proper function. Our study aimed at investigating the relationship between the elastin concentration of the wall of normal and aneurysmal abdominal aortas (AAA), the collagen concentration, and its extractability, as a function of their size. Infrarenal aortas were collected from 30 patients undergoing operative repair of abdominal aortic aneurysm. Age-matched control samples were obtained from eight autopsies of individuals without vascular disease. Samples were divided into five groups according to the aortic diameter: control group (group N, n = 8); < 50 mm (group I, n = 6; between 50-75 mm (group II, n = 10); > 75 mm (group III, n = 7); and ruptured (group IV, n = 7). The collagen concentration in samples from group I was similar to the controls. An increased collagen concentration was observed in group II and remained at the same level in the largest and ruptured aneurysms. Extractability of collagen was found to be increased in group III and was even higher in group IV. A highly significant reduction in elastin concentration was observed in group I and there was progressive reduction with increasing diameter and rupture. A significant correlation could be established between aortic diameter, increased collagen extractability and decreased elastin content.

Topics: Aged; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortic Rupture; Collagen; Elastin; Extracellular Matrix; Female; Humans; Male

Inflammatory aneurysms (IAs) have peculiar macroscopic and histological aspects which make them very different from nonspecific aneurysms (NSAs). These morphological differences seem to be determined by significant modifications of the extracellular matrix. Extracellular matrix protein component concentrations were determined biochemically in infrarenal aortic biopsies from 10 NSAs, five IAs and five non-aneurysmal aortic controls. The concentration of each wall component was expressed in % w/w (relative concentration) and in mg/wall longitudinal cm (absolute concentration) with reference to total protein recovered after hydrolysis and amino acid analysis. The biochemical results were correlated with the histological and ultrastructural features of the specimens. A significant increase in total collagen was observed in the two groups of aneurysms, with respect to the controls (NSA = 285%, IA = 382%). In contrast the 80-90% decrease in the relative concentration of elastin observed in both types of aneurysm was less marked (NSA = 55%, IA = 39%). This fall was not significant when expressed in mg/cm, although elastin derived peptide (EDP) levels in the plasma of these patients was significantly higher than in age-matched controls. The concentration of the soluble collagen fraction appeared significantly higher (Mann-Whitney, p < 0.05) in the IAs with respect to the NSAs, whilst no differences were observed between the two groups regarding the concentration of insoluble elastin and of wall and plasma EDPs. As well as providing evidence of increased elastin turnover, this study emphasises the conspicuous modifications of collagen deposition in the wall of abdominal aortic aneurysms which appeared more marked in the inflammatory group.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Aged; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Collagen; Elastin; Extracellular Matrix Proteins; Humans; Inflammation; Microscopy, Electron; Microscopy, Electron, Scanning; Middle Aged

A blister on an aortic aneurysm represents the final stage before rupture, regardless of patient symptoms or aneurysm size. The mechanisms of rupture are unclear but probably involve defects in the elastin and collagen matrices.

Topics: Aged; Aged, 80 and over; Aortic Aneurysm, Abdominal; Aortic Rupture; Collagen; Diverticulum; Elastin; Humans; Male

Adventitial elastin degradation is a hallmark of abdominal aortic aneurysm (AAA) formation in human beings, although the quantitative relationship between elastin loss and AAA formation and growth is unknown. This study was undertaken to quantitate the reduction of adventitial elastin for small AAA, to determine whether the loss of this structural component parallels aneurysm growth, and to examine the ultrastructure of the remaining elastin elements.. Longitudinal strips of anterior aneurysm wall were taken from 12 patients having elective repair of small (diameter < 5 cm, n = 4), moderate (diameter < 5 to 7 cm, n = 4), or large (diameter > 7 cm, n = 4) AAA and from six normal control subjects at autopsy. Specimens were prepared with elastin and collagen stains for histologic examination or formic acid for scanning electron microscopic evaluation of elastin architecture. Adventitial elastin content of aneurysmal and control aortas was quantitated with video microscopy and compared by aneurysm diameter.. The inner portion of adventitia of normal aortic wall was composed of densely compacted alternating lamellae of elastin and collagen, which were grossly disrupted in all aneurysms. The remaining elastin fibers were disorganized and tortuous. There was an 81.6% +/- 2.1% reduction in elastin lamellae and an 85.7% +/- 4.2% reduction in fibers per lamellae compared with the number in control aortas (p < 0.001). Size of the aneurysm made no difference in adventitial elastin content.. These data strongly suggest that elastolysis is a primary event in AAA formation that occurs before over loss of adventitial structural integrity and the development of small aneurysms.

Topics: Aged; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Elastic Tissue; Elastin; Female; Histocytological Preparation Techniques; Humans; Male; Microscopy, Electron, Scanning; Middle Aged

Accumulating evidence suggests that abdominal aortic aneurysms (AAA) are due to a pathologic process which results in the destruction of aortic elastin and other matrix components. In this study, protein extractions were performed on both aneurysmal and normal aorta. Extracts were applied to frozen section of normal aorta either alone or in combination with 10 mM ethylenediaminetetraacetic acid, recombinant tissue inhibitor of metalloproteases, 10 mM zinc, and 5 mM phenylmethylsulfonyl fluoride, under conditions where calcium was removed from the buffer. After incubation, the sections were stained for elastin and evaluated by computerized morphometry. Aneurysm extracts, only in the presence of calcium, showed significant elastolytic activity characterized by destruction of intact elastic lamellae that was inhibited by ethylenediaminetetraacetic acid, the recombinant metalloprotease inhibitor, and zinc. Phenylmethylsulfonyl fluoride showed no inhibitory activity. Healthy aortic extract showed no elastolytic activity. This inhibitory profile is consistent with a metalloenzyme. We conclude that aneurysmal aorta contains elastolytic activity that is secondary to a metalloenzyme which is not present in normal aorta. This activity may play a role in the destruction of the elastin matrix that is seen in AAA's.

Topics: Aorta, Abdominal; Aortic Aneurysm, Abdominal; Edetic Acid; Elastin; Humans; Metalloendopeptidases; Pancreatic Elastase; Phenylmethylsulfonyl Fluoride; Tissue Extracts; Zinc

The mechanical properties of the abdominal aorta were investigated non-invasively in 30 patients with aortic aneurysm and 11 with peripheral arterial disease. The distensibility of the aorta was measured using M-mode ultrasonography, permitting non-invasive assessment of the pressure--strain elastic modulus or aortic stiffness, Ep. The median Ep value increased from 4.0 N/cm2 in control subjects in their third decade of life (n = 10) to 10.4 N/cm2 in middle age (n = 11) to 14.0 N/cm2 in the elderly (n = 13). In the presence of a normal diameter, peripheral arterial disease with aortic atherosclerosis had little effect on aortic stiffness, median Ep being 16.0 N/cm2. Aneurysmal dilatation was associated with a significant increase in aortic stiffness, median Ep being 31.3 N/cm2 (P < 0.001). For aortas of normal diameter, Ep was at all ages dependent on mean arterial pressure. In patients with aortic aneurysms there was no clear relationship between Ep and mean arterial pressure or aortic diameter. Of the patients studied, 15 underwent aortic reconstruction; increasing aortic stiffness (log Ep) was associated with a decreased medial elastin content of the aortic biopsy (r = -0.63, P < 0.02). This study demonstrates the marked stiffness or inelasticity of dilated or aneurysmal vessels, part of which is attributable to the loss of elastin.

Topics: Adult; Aged; Aged, 80 and over; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Biomechanical Phenomena; Blood Pressure; Elasticity; Elastin; Female; Humans; Male; Middle Aged