transforming-growth-factor-beta and Aortic-Aneurysm

Aortic dissection and aortic aneurysms are currently among the most high-risk cardiovascular diseases due to their rapid onset and high mortality. Although aneurysm research has been extensive, the pathogenesis remains unknown. Studies have found that the TGF-β/Smad pathway and aneurysm formation appear linked. For example, the TGF-β signaling pathway was significantly activated in aneurysm development and aortic dissection. Aneurysms are not, however, mitigated following knockdown of TGF-β signaling pathway-related genes. Incidence and mortality rate of ruptured thoracic aneurysms increase with the down-regulation of the classical TGF-β signaling pathway. In this review, we summarize recent findings and evaluate the differential role of classical and non-classical TGF-β pathways on aortic aneurysm. It is postulated that the TGF-β signaling pathway is necessary to maintain vascular function, but over-activation will promote aneurysms whereas over-inhibition will lead to bypass pathway over-activation and promote aneurysm occurrence.

Topics: Animals; Aortic Aneurysm; Humans; Signal Transduction; Transforming Growth Factor beta

Aortic structure and function are controlled by the coordinated actions of different aortic cells and the extracellular matrix. Several pathways have been identified that control the aortic wall in a cell-type-specific manner and play diverse roles in various phases of aortic injury, repair, and remodeling. This complexity of signaling in the aortic wall poses challenges to the development of therapeutic strategies for treating aortic aneurysms and dissections. Here, in part II of this Recent Highlights series on aortic aneurysms and dissections, we will summarize recent studies published in

Topics: Aortic Aneurysm; Aortic Dissection; Extracellular Matrix; Humans; Mutation; Receptors, Angiotensin; Signal Transduction; Transforming Growth Factor beta

Marfan syndrome is an autosomal dominant connective tissue disease with an estimated incidence of 1 in 5000 individuals. In 90% of cases it is caused by mutations in the gene for fibrillin-1, the main constituent of extracellular microfibrils. Studies on animal models of Marfan syndrome have revealed that fibrillin-1 mutations interfere with local TGF-β signaling, in addition to impairing tissue integrity. The cardinal features involve the cardiovascular, ocular and skeletal systems. The diagnosis of Marfan syndrome is made according to the revised Ghent nosology. Early identification and appropriate management are critical for patients with Marfan syndrome, who are prone to the life-threatening cardiovascular complications of aortic aneurysms and aortic dissection. The standard treatment includes prophylactic beta-blockers in order to slow down dilation of the ascending aorta, and prophylactic aortic surgery. The success of current medical and surgical treatment of aortic disease in Marfan syndrome has substantially improved mean life expectancy, extending it above 72 years. This review aims to provide an overview of this hereditary disorder.

Topics: Adrenergic beta-Antagonists; Animals; Aorta; Aortic Aneurysm; Aortic Dissection; Fibrillin-1; Marfan Syndrome; Mutation; Transforming Growth Factor beta

Aortic aneurysm is a vascular disease whereby the ECM (extracellular matrix) of a blood vessel degenerates, leading to dilation and eventually vessel wall rupture. Recently, it was shown that calcification of the vessel wall is involved in both the initiation and progression of aneurysms. Changes in aortic wall structure that lead to aneurysm formation and vascular calcification are actively mediated by vascular smooth muscle cells. Vascular smooth muscle cells in a healthy vessel wall are termed contractile as they maintain vascular tone and remain quiescent. However, in pathological conditions they can dedifferentiate into a synthetic phenotype, whereby they secrete extracellular vesicles, proliferate, and migrate to repair injury. This process is called phenotypic switching and is often the first step in vascular pathology. Additionally, healthy vascular smooth muscle cells synthesize VKDPs (vitamin K-dependent proteins), which are involved in inhibition of vascular calcification. The metabolism of these proteins is known to be disrupted in vascular pathologies. In this review, we summarize the current literature on vascular smooth muscle cell phenotypic switching and vascular calcification in relation to aneurysm. Moreover, we address the role of vitamin K and VKDPs that are involved in vascular calcification and aneurysm. Visual Overview- An online visual overview is available for this article.

Topics: Aortic Aneurysm; Elastin; Humans; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Oxidative Stress; Phenotype; Transforming Growth Factor beta; Vascular Calcification; Vitamin K; Vitamin K Epoxide Reductases

Genetic studies in animals and humans indicate that gene mutations that functionally perturb transforming growth factor β (TGF-β) signaling are linked to specific hereditary vascular syndromes, including Osler-Rendu-Weber disease or hereditary hemorrhagic telangiectasia and Marfan syndrome. Disturbed TGF-β signaling can also cause nonhereditary disorders like atherosclerosis and cardiac fibrosis. Accordingly, cell culture studies using endothelial cells or smooth muscle cells (SMCs), cultured alone or together in two- or three-dimensional cell culture assays, on plastic or embedded in matrix, have shown that TGF-β has a pivotal effect on endothelial and SMC proliferation, differentiation, migration, tube formation, and sprouting. Moreover, TGF-β can stimulate endothelial-to-mesenchymal transition, a process shown to be of key importance in heart valve cushion formation and in various pathological vascular processes. Here, we discuss the roles of TGF-β in vasculogenesis, angiogenesis, and lymphangiogenesis and the deregulation of TGF-β signaling in cardiovascular diseases.

Topics: Activin Receptors, Type II; Animals; Aortic Aneurysm; Atherosclerosis; Cardiovascular Diseases; Cell Communication; Endothelial Cells; Fibrosis; Humans; Hypertension, Pulmonary; Lymphangiogenesis; Myocardium; Neovascularization, Physiologic; Signal Transduction; Telangiectasia, Hereditary Hemorrhagic; Transforming Growth Factor beta

Aortic aneurysms are morbid conditions that can lead to rupture or dissection and are categorized as thoracic (TAA) or abdominal aortic aneurysms (AAA) depending on their location. While AAA shares overlapping risk factors with atherosclerotic cardiovascular disease, TAA exhibits strong heritability. Human genetic studies in the past two decades have successfully identified numerous genes involved in both familial and sporadic forms of aortic aneurysm. In this review we will discuss the genetic basis of aortic aneurysm, focusing on the extracellular matrix and how insights from these studies have informed our understanding of human biology and disease pathogenesis.

Topics: Animals; Aortic Aneurysm; Aortic Aneurysm, Abdominal; Aortic Aneurysm, Thoracic; Extracellular Matrix; Genetic Predisposition to Disease; Humans; Mutation; Signal Transduction; Transforming Growth Factor beta

Topics: Animals; Aortic Aneurysm; Aortic Dissection; Humans; Marfan Syndrome; Mutation; Transforming Growth Factor beta

Marfan syndrome (MFS) is an autosomal dominant heritable disorder of connective tissue that affects the cardiovascular, skeletal, ocular, pulmonary, and nervous systems and is usually caused by mutations in the FBN1 gene, which encodes fibrillin-1. MFS is traditionally considered to result from the structural weakness of connective tissue. However, recent investigations on molecular mechanisms indicate that increased transforming growth factor-β (TGF-β) activity plays a crucial role in the pathogenesis of MFS and related disorders, such as Loeys-Dietz syndrome (LDS), which is caused by mutation in TGF-β signaling-related genes. In addition, recent studies show that angiotensin II type 1 receptor (AT1R) signaling enhances cardiovascular pathologies in MFS, and the angiotensin II receptor blocker losartan has the potential to inhibit aortic aneurysm formation. However, the relationship between TGF-β and AT1R signaling pathways remains poorly characterized. In this review, we discuss the recent studies on the molecular mechanisms underlying cardiovascular manifestations of MFS and LDS and the ensuing strategies for management.

Topics: Angiotensin II Type 1 Receptor Blockers; Animals; Aortic Aneurysm; Disease Management; Fibrillin-1; Humans; Loeys-Dietz Syndrome; Losartan; Marfan Syndrome; Signal Transduction; Transforming Growth Factor beta

The recent studies of molecular physiology of fibrillin and pathophysiology of inherent disorders of structure and function of connective tissue such as dissection and aneurysm of aorta, myxomatously altered cusps and prolapses of mitral valve, syndrome of hyper-mobility of joints, demonstrated that important role in development of these malformations play alterations of transfer of signals by growth factors and matrix cellular interaction. These conditions under manifesting Marfan's syndrome can be a consequence of anomalies of fibrillin-1 which deficiency unbrakes process of activation of transforming growth factor-β (TGFβ). The involvement of TGFβ in pathogenesis of Marfan's syndrome permits consider antagonists of angiotensin-transforming enzymes as potential pharmaceuticals in therapy of this disease. The article presents analysis of publications' data related to this problem.

Topics: Angiotensin-Converting Enzyme Inhibitors; Aortic Aneurysm; Aortic Dissection; Connective Tissue; Fibrillin-1; Fibrillins; Gene Expression Regulation; Humans; Joint Instability; Marfan Syndrome; Microfilament Proteins; Mitral Valve Prolapse; Peptidyl-Dipeptidase A; Signal Transduction; Transforming Growth Factor beta

Topics: Actins; Animals; Aortic Aneurysm; Atherosclerosis; Humans; Inflammation; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Phenotype; Polymerization; Transforming Growth Factor beta; Vascular Remodeling

Aneurysms are local dilations of an artery that predispose the vessel to sudden rupture. They are often asymptomatic and undiagnosed, resulting in a high mortality rate. The predisposition to develop thoracic aortic aneurysms is often genetically inherited and associated with syndromes affecting connective tissue homeostasis. This review discusses how elucidation of the genetic causes of syndromic forms of thoracic aortic aneurysm has helped identify pathways that contribute to disease progression, including those activated by TGF-β, angiotensin II and Notch ligands. We also discuss how pharmacological manipulation of these signaling pathways has provided further insight into the mechanism of disease and identified compounds with therapeutic potential in these and related disorders.

Topics: Animals; Aortic Aneurysm; Disease Models, Animal; Genetic Predisposition to Disease; Humans; Mice; Signal Transduction; Transforming Growth Factor beta

This review discusses the role of biomarkers for both diagnoses and disease monitoring before, during, and after treatment of aortic dissection.

Topics: Aortic Aneurysm; Aortic Dissection; Biomarkers; C-Reactive Protein; Calcium-Binding Proteins; Calponins; Elastin; Endothelin-1; Fibrin Fibrinogen Degradation Products; Humans; Microfilament Proteins; Natriuretic Peptide, Brain; Peptide Fragments; Peptidyl-Dipeptidase A; Receptors, Notch; Smooth Muscle Myosins; Transforming Growth Factor beta

The starting point, in Marfan syndrome (MFS) appears to be the mutation of fibrillin-1 gene whose deconstructed protein product cannot bind transforming growth factor beta (TGF-b), leading to an increased TGF-b tissue level. The aim of this review is to review the already known features of the cellular signal transduction downstream to TGF-b and its impact on the tissue homeostasis of microfibrils, and elastic fibers. We also investigate current data on the extracellular regulation of TGF-b level including mechanotransduction and the feedback cycles of integrin-dependent and independent activation of the latent TGF-b complex. Together these factors, by the destruction of the connective tissue fibers, may play an important role in the development of the diverse cardiac and extracardiac manifestations of MFS and many of them could be a target of conservative treatment. We present currently investigated drugs for the treatment of the syndrome, and explore possible avenues of research into pathogenesis of MFS in order to improve understanding of the disease.

Topics: Animals; Aortic Aneurysm; Humans; Marfan Syndrome; Prognosis; Signal Transduction; Transforming Growth Factor beta

Angiotensin II (AngII) has been invoked as a principal mediator for the development and progression of both thoracic and abdominal aortic aneurysms. While there is consistency in experimental and clinical studies that overactivation of the renin angiotensin system promotes aortic aneurysm development, there are many unknowns regarding the mechanistic basis underlying AngII-induced aneurysms. Interactions of AngII with TGF-β in both thoracic and abdominal aortic aneurysms have been the focus of recent studies. While these studies have demonstrated profound effects of manipulating TGF-β activity on AngII-induced aortic aneurysms, they have also led to more questions regarding the interactions between AngII and this multifunctional cytokine. This review compiled the recent literature to provide insights into understanding the potentially complex interactions between AngII and TGF-β in the development of aortic aneurysms.

Topics: Angiotensin II; Animals; Aortic Aneurysm; Humans; Transforming Growth Factor beta

One of the critical points in the pathogenesis of aortic aneurysms (AAs) is the disruption of the balance between vascular extracellular matrix (ECM) deposition and degradation. AAs are common features in some genetically determined diseases of the connective tissue, such as Marfan and Ehlers-Danlos. Acquired factors determining an enhanced inflammatory state of the arterial wall also play a key role. Previous studies have determined the role of tumor growth factor β (TGF-β); as a principal mediator of the pathogenesis of the alterations of the arterial wall homeostasis in AAs. The medical management of any AA is mainly focused on the use of pharmacological agents that reduce hemodynamic stress of the aortic wall, since hypertension is the major risk factor for the enlargement and rupture of the AAs. However, this is far from being a comprehensive pathophysiology-based therapeutic approach. Drugs potentially able to reduce the release of TGF-β may play a role in the pathogenesis of the AAs. They work by improving matrix repair, decreasing the proteolytic pattern and inhibition of angiotensin-converting enzyme (ACE) as well as preventing angiotensin II-induced angiotensin type-1 receptor (AT1R) activation. A new pathophysiology-based therapeutic approach, involving the mechanisms leading to the rupture of the AAs, could represent an additional tool in combination with the current established antihypertensive therapy.

Topics: Animals; Aortic Aneurysm; Atherosclerosis; Autoimmunity; Genetic Predisposition to Disease; Humans; Hypertension; Insulin Resistance; Metalloproteases; Oxidative Stress; Risk Factors; Transforming Growth Factor beta

Aortic aneurysm is common, accounting for 1-2% of all deaths in industrialized countries. Early theories of the causes of human aneurysm mostly focused on inherited or acquired defects in components of the extracellular matrix in the aorta. Although several mutations in the genes encoding extracellular matrix proteins have been recognized, more recent discoveries have shown important perturbations in cytokine signalling cascades and intracellular components of the smooth muscle contractile apparatus. The modelling of single-gene heritable aneurysm disorders in mice has shown unexpected involvement of the transforming growth factor-β cytokine pathway in aortic aneurysm, highlighting the potential for new therapeutic strategies.

Topics: Angiotensin II; Animals; Aortic Aneurysm; Disease Models, Animal; Elastin; Humans; Muscle, Smooth, Vascular; Transforming Growth Factor beta

Topics: Aortic Aneurysm; Elasticity; Hemodynamics; Humans; Intracranial Aneurysm; Organ Specificity; Risk Factors; Transforming Growth Factor beta

The lethality of acute aortic dissection is well recognized. Successful treatment and prevention of aortic dissection is going to be dependent upon an improved understanding of the molecular and physiologic events which predispose to dissection development and propagation. In this review, we will focus on the elastic fiber, one of the critical elements of the aortic wall matrix. Mechanical or functional failure of the elastin in the wall of the aorta likely predisposes to dissection as well as the post-dissection aortic degeneration with aneurysm formation. Insight into the role of the elastin and the elastic fiber in aortic dissection has recently been accelerated by research into the molecular mechanisms associated with hereditary propensity for aortic dissection, such as Marfan syndrome. These studies have implicated both structural and metabolic contributions of alterations in the scaffolding proteins in matrix elastic fibers. In particular, increased transforming growth factor-β (TGF-β) activity may play a prominent role in predisposing the aortic wall to dissection. The events which predispose to post-dissection aortic degeneration are somewhat less well defined. However, the loss of the structural integrity of the remaining elastic fibers leaves the wall weaker and prone to dilatation and rupture. It appears likely that the upregulation of several potent proteases, particularly those of the matrix metalloproteinase (MMP) family such as MMP-9, are participating in the subsequent matrix damage. Novel medical treatments based on this pathologic data have been proposed and in some cases have made it to clinical trials. The ongoing study evaluating whether therapeutic inhibition of TGF-β may be useful in reducing the risk of aortic dissection in patients at high risk represents one promising new strategy in the treatment of this deadly disease.

Topics: Acute Disease; Aortic Aneurysm; Aortic Dissection; Aortic Rupture; Elastic Tissue; Hemodynamics; Humans; Matrix Metalloproteinases; Transforming Growth Factor beta

Aortic aneurysm (AA) is a common health problem with high mortality and no effective drugs. Transforming growth factor-β (TGF-β) superfamily members regulate various cellular processes, and TGF-β signaling has key roles in development, tissue homeostasis, and diseases. Interest in the role of TGF-β signaling in the pathogenesis of AAs has recently emerged, particularly since genetic studies demonstrated an association between gene mutations in components of TGF-β signaling and AAs. However, paradoxical discoveries have implicated dysregulated TGF-β signaling in aneurysm formation, complicating the precise functional role for TGF-β in aneurysm development and progression. Furthermore, interventions targeting towards TGF-β signaling using losartan, which may represent a suitable therapeutic option for AAs, were subject to skepticism especially because of conflicting experimental results obtained from TGF-β antibody treatment without knowledge of the underlying mechanism. We propose a TGF-β aneurysm paradox, which would provide a good opportunity for the development of genetic mouse models of AA. These models would be used to clarify the mechanisms underlying TGF-β signaling, which would translate into novel pharmacologic therapies based on the new molecular discoveries.

Topics: Angiotensin II; Animals; Aortic Aneurysm; Disease Models, Animal; Humans; Signal Transduction; Smad Proteins; Transforming Growth Factor beta

Aortic aneurysms are an important cause of mortality in the western world. Monogenic disorders such as the Marfan syndrome (MFS) are good genetic models for the pathogenesis of aortic aneurysm. In the MFS, progressive dilatation of the aortic root leads to aortic aneurysm and dissection, often associated with precocious death. Early pathogenetic models for MFS focused upon structural weakness of the tissues imposed by microfibrillar deficiency. However, recent studies of transgenic mouse models have challenged this model and demonstrated a central role for the upregulation of the TGFbeta signaling pathway. The discovery of a new aortic aneurysm syndrome, the Loeys-Dietz syndrome (LDS), confirmed the importance of the cytokine TGFbeta in aneurysm pathogenesis. The main distinguishing features between LDS and MFS include the presence of hypertelorism, cleft palate/bifid uvula and arterial tortuosity. LDS is caused by mutations in the genes encoding the receptors for TGFbeta (TGFBR1/2). This insight helped to elucidate the pathogenesis of another rare autosomal recessive connective tissue disorder, arterial tortuosity syndrome. This disease is caused by mutations in the SLC2A10 gene, coding for GLUT10, a member of the glucose transporter family. In analogy to LDS, we demonstrated an upregulation of TGFbeta in ATS. Finally, all these insights have also lead to new therapeutic insights. In transgenic mouse models it was shown that losartan, an angiotensin II type 1 receptor with known inhibiting effects on TGFbeta, rescues the aortic phenotype. If these promising results are confirmed in human trials, losartan might have beneficial effects in the treatment of more common nonhereditary aortic aneurysms.

Topics: Abnormalities, Multiple; Animals; Animals, Genetically Modified; Aortic Aneurysm; Aortic Aneurysm, Thoracic; Disease Models, Animal; Humans; Marfan Syndrome; Mice; Models, Genetic; Transforming Growth Factor beta; Up-Regulation

Ascending thoracic aortic aneurysms leading to type A dissections (TAAD) can occur in association with a genetic syndrome, such as Marfan syndrome (MFS), or as an autosomal dominant disorder in the absence of syndromic features, termed familial TAAD. Familial TAAD demonstrates genetic heterogeneity, and linkage studies have identified three TAAD loci at 5q13-14 (TAAD1), 11q23 (FAA1), and 3p24-25 (TAAD2). The underlying genetic heterogeneity of TAAD is reflected in the phenotypic variation associated with familial TAAD with respect to age of onset, progression, penetrance, and association with additional cardiac and vascular features. Recently, mutations in the TGFBR2 gene have been identified as the cause of disease linked to the TAAD2 locus, supporting the hypothesis that dysregulation of TGFbeta signaling is a mechanism leading to aneurysms and dissections. The recent identification of the TGFbeta pathway as a key target in the molecular pathogenesis of TAAD has opened new avenues for future genetic and therapeutic research.

Topics: Aortic Aneurysm; Fibrillins; Genes, Dominant; Genetic Predisposition to Disease; Humans; Intracellular Signaling Peptides and Proteins; Latent TGF-beta Binding Proteins; Microfilament Proteins; Mutation; Penetrance; Protein Serine-Threonine Kinases; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta; Signal Transduction; Transforming Growth Factor beta

Current treatment of aortic abdominal aneurysms by conventional surgery or endoprosthesis is flawed by high post-operative mortality and unpredictable durability of haemodynamic exclusion, respectively. We have developed endovascular approaches with cell and gene transfer, aimed at controlling further diameter expansion in an animal model of already-developed aneurysms in rats. Preliminary results suggest that both cell and gene endovascular therapy can be used to control expansion of aneurysms generated by inflammation and proteolytic destruction of the aortic wall.

Topics: Animals; Aortic Aneurysm; Cell Transplantation; Disease Models, Animal; Genetic Therapy; Muscle, Smooth, Vascular; Paracrine Communication; Rats; Transforming Growth Factor beta

Aortic dissection and aneurysm are common clinical problems with life-threatening consequences; they are also the hallmark of several genetic diseases, including Marfan's syndrome (MFS). In spite of clinical and surgical advances that have increased life expectancy for affected patients, cardiovascular manifestations remain significant contributors to morbidity and mortality in MFS. Dissecting aortic aneurysm in this disorder is accounted for by mutations in fibrillin-1, the major component of the microfibrils associated with elastin in the elastic fibers of the aortic media. Genetic studies of human patients and murine models have yielded invaluable insights into the pathophysiology of aneurysm formation and progression in MFS. They have also revealed a previously unappreciated role of microfibrils in regulating transforming growth factor and bone morphogenetic protein signaling. As a result, exciting new hypotheses have emerged regarding the pathogenesis of MFS, as well as opportunities to explore translational applications of this information that may be relevant to various manifestations of the disease.

Topics: Adrenergic beta-Antagonists; Animals; Aortic Aneurysm; Aortic Dissection; Disease Progression; Fibrillin-1; Fibrillins; Humans; Marfan Syndrome; Microfibrils; Microfilament Proteins; Mutation; Transforming Growth Factor beta; Vascular Surgical Procedures

The major clinical problem of Marfan syndrome (MFS) is the aortic root aneurysm, with risk of dissection when the root diameter approximates 5 cm. In MFS, a key molecule, transforming growth factor-beta (TGF-beta), normally bound to the extracellular matrix, is free and activated. In an experimental setting, TGF-beta blockade prevents the aortic root structural damage and dilatation. The angiotensin receptor 1 blockers (sartanics) exert an anti-TGF-beta effect; trials are now ongoing for evaluating the effect of losartan compared with atenolol in MFS. beta-Adrenergic blockers are the drugs most commonly used in MFS. The third-generation beta-adrenergic blocker nebivolol retains the beta-adrenergic blocker effects on heart rate and further exerts antistiffness effects, typically increased in MFS.. The open-label phase III study will include 291 patients with MFS and proven FBN1 gene mutations, with aortic root dilation (z-score > or =2.5). The patients will be randomized to nebivolol, losartan and the combination of the two drugs. The primary end point is the comparative evaluation of the effects of losartan, nebivolol and the association of both on the progression of aortic root growth rate. Secondary end points include the pharmacokinetics of the two drugs, comparative evaluation of serum levels of total and active TGF-beta, quantitative assessment of the expression of the mutated gene (FBN1, both 5' and 3'), pharmacogenetic bases of drug responsiveness. The quality of life evaluation in the three groups will be assessed. Statistical evaluation includes an interim analysis at month 24 and conclusive analyses at month 48.. The present study will add information about pharmacological therapy in MFS, supporting the new application of angiotensin receptor 1 blockers and finding beta-adrenergic blockers that may give more specific effects. Moreover, the study will further deepen understanding of the pathogenetic mechanisms that are active in Marfan syndrome through the pharmacogenomic and transcriptomic mechanisms that may explain MFS phenotype variability.

Topics: Adolescent; Adrenergic beta-Antagonists; Adult; Angiotensin II Type 1 Receptor Blockers; Aortic Aneurysm; Benzopyrans; Child; Child, Preschool; Dilatation, Pathologic; Disease Progression; Ethanolamines; Female; Fibrillin-1; Fibrillins; Humans; Infant; Losartan; Male; Marfan Syndrome; Microfilament Proteins; Middle Aged; Mutation; Nebivolol; Quality of Life; Research Design; Time Factors; Transforming Growth Factor beta; Treatment Outcome; Young Adult

Topics: Aged; Aorta; Aortic Aneurysm; Atherosclerosis; Calcium; Case-Control Studies; Female; Heart Disease Risk Factors; Humans; Lipid Metabolism; Lipoproteins, HDL; Lipoproteins, LDL; Male; Matrix Metalloproteinases; Protective Factors; Signal Transduction; Transforming Growth Factor beta; Triglycerides

Mural cells in ascending aortic aneurysms undergo phenotypic changes that promote extracellular matrix destruction and structural weakening. To explore this biology, we analyzed the transcriptional features of thoracic aortic tissue.. Single-nuclear RNA sequencing was performed on 13 samples from human donors, 6 with thoracic aortic aneurysm, and 7 without aneurysm. Individual transcriptomes were then clustered based on transcriptional profiles. Clusters were used for between-disease differential gene expression analyses, subcluster analysis, and analyzed for intersection with genetic aortic trait data.. We sequenced 71 689 nuclei from human thoracic aortas and identified 14 clusters, aligning with 11 cell types, predominantly vascular smooth muscle cells (VSMCs) consistent with aortic histology. With unbiased methodology, we found 7 vascular smooth muscle cell and 6 fibroblast subclusters. Differentially expressed genes analysis revealed a vascular smooth muscle cell group accounting for the majority of differential gene expression. Fibroblast populations in aneurysm exhibit distinct behavior with almost complete disappearance of quiescent fibroblasts. Differentially expressed genes were used to prioritize genes at aortic diameter and distensibility genome-wide association study loci highlighting the genes. Using nuclear RNA sequencing, we describe the cellular diversity of healthy and aneurysmal human ascending aorta. Sporadic aortic aneurysm is characterized by differential gene expression within known cellular classes rather than by the appearance of novel cellular forms. Single-nuclear RNA sequencing of aortic tissue can be used to prioritize genes at aortic trait loci.

Topics: Actinin; Aorta; Aortic Aneurysm; Aortic Aneurysm, Thoracic; Genome-Wide Association Study; Humans; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; RNA, Nuclear; Sequence Analysis, RNA; Transforming Growth Factor beta

[Figure: see text].

Topics: Animals; Aorta; Aortic Aneurysm; Cell Adhesion Molecules; Dilatation, Pathologic; Endothelium, Vascular; Female; Male; Mice, Inbred C57BL; Mice, Knockout; Microfilament Proteins; Muscle, Smooth, Vascular; Myosin Heavy Chains; Nitric Oxide; Nitric Oxide Synthase Type III; Phosphoproteins; Phosphorylation; Receptor, Transforming Growth Factor-beta Type II; Signal Transduction; Transforming Growth Factor beta; Vasoconstriction

We investigated the effect of a potent TGFβ (transforming growth factor β) inhibitor peptide (P144) from the betaglycan/TGFβ receptor III on aortic aneurysm development in a Marfan syndrome mouse model.. We used a chimeric gene encoding the P144 peptide linked to apolipoprotein A-I via a flexible linker expressed by a hepatotropic adeno-associated vector. Two experimental approaches were performed: (1) a preventive treatment where the vector was injected before the onset of the aortic aneurysm (aged 4 weeks) and followed-up for 4 and 20 weeks and (2) a palliative treatment where the vector was injected once the aneurysm was formed (8 weeks old) and followed-up for 16 weeks. We evaluated the aortic root diameter by echocardiography, the aortic wall architecture and TGFβ signaling downstream effector expression of pSMAD2 and pERK1/2 by immunohistomorphometry, and Tgfβ1 and Tgfβ2 mRNA expression levels by real-time polymerase chain reaction. Marfan syndrome mice subjected to the preventive approach showed no aortic dilation in contrast to untreated Marfan syndrome mice, which at the same end point age already presented the aneurysm. In contrast, the palliative treatment with P144 did not halt aneurysm progression. In all cases, P144 improved elastic fiber morphology and normalized pERK1/2-mediated TGFβ signaling. Unlike the palliative treatment, the preventive treatment reduced Tgfβ1 and Tgfβ2 mRNA levels.. P144 prevents the onset of aortic aneurysm but not its progression. Results indicate the importance of reducing the excess of active TGFβ signaling during the early stages of aortic disease progression.

Topics: Animals; Aorta; Aortic Aneurysm; Dependovirus; Dilatation, Pathologic; Disease Models, Animal; Female; Fibrillin-1; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Male; Marfan Syndrome; Mice, Inbred C57BL; Peptide Fragments; Proteoglycans; Receptors, Transforming Growth Factor beta; Signal Transduction; Transforming Growth Factor beta

Aortic root aneurysm formation is a cardinal feature of Marfan syndrome (MFS) and likely TGF-β driven via Smad (canonical) and ERK (non-canonical) signalling. The current study assesses human MFS vascular smooth muscle cell (SMC) phenotype, focusing on individual contributions by Smad and ERK, with Notch3 signalling identified as a novel compensatory mechanism against TGF-β-driven pathology. Although significant ERK activation and mixed contractile gene expression patterns were observed by traditional analysis, this did not directly correlate with the anatomic site of the aneurysm. Smooth muscle cell phenotypic changes were TGF-β-dependent and opposed by ERK in vitro, implicating the canonical Smad pathway. Bulk SMC RNA sequencing after ERK inhibition showed that ERK modulates cell proliferation, apoptosis, inflammation, and Notch signalling via Notch3 in MFS. Reversing Notch3 overexpression with siRNA demonstrated that Notch3 promotes several protective remodelling pathways, including increased SMC proliferation, decreased apoptosis and reduced matrix metalloproteinase activity, in vitro. In conclusion, in human MFS aortic SMCs: (a) ERK activation is enhanced but not specific to the site of aneurysm formation; (b) ERK opposes TGF-β-dependent negative effects on SMC phenotype; (c) multiple distinct SMC subtypes contribute to a 'mixed' contractile-synthetic phenotype in MFS aortic aneurysm; and (d) ERK drives Notch3 overexpression, a potential pathway for tissue remodelling in response to aneurysm formation.

Topics: Aorta; Aortic Aneurysm; Apoptosis; Cell Line; Cell Proliferation; Humans; Inflammation; Marfan Syndrome; Muscle Contraction; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Phenotype; Receptor, Notch3; Signal Transduction; Transforming Growth Factor beta

The etiology of aortic aneurysms is poorly understood, but it is associated with atherosclerosis, hypercholesterolemia, and abnormal transforming growth factor β (TGF-β) signaling in smooth muscle. Here, we investigated the interactions between these different factors in aortic aneurysm development and identified a key role for smooth muscle cell (SMC) reprogramming into a mesenchymal stem cell (MSC)-like state. SMC-specific ablation of TGF-β signaling in Apoe

Topics: Animals; Aorta; Aortic Aneurysm; Cellular Reprogramming; Mice; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Transforming Growth Factor beta

The sympathetic system is involved in the arterial diseases, but its mechanism remains poorly understood. The present study aimed to explore the impact of the sympathetic neurotransmitter norepinephrine (NE) on transforming growth factor (TGF) β signaling and the role of NE in aortic remodeling. Guanethidine was used to induce a regional chemical sympathetic denervation (CSD) in angiotensin II (AngII) and β‑aminopropionitrile (BAPN)‑induced aortic aneurysm models. The diameter of the aorta was measured, and elastic fiber staining was performed. TGFβ type I receptor kinase (ALK5) expression in rat aortic NE‑treated vascular smooth muscle cells (VSMCs) was detected by reverse transcription‑quantitative PCR and western blotting. The effects of NE and ALK5 overexpression on migration, proliferation, apoptosis and TGFβ signaling were also evaluated. Furthermore, adrenergic receptor blockers were used to determine which receptor was involved in the modulation on TGFβ signaling by NE. The results of the present study demonstrated that CSD protected rats from AngII+BAPN‑induced aortic remodeling and aneurysm formation. Compared with the control group, NE inhibited VSMC proliferation and migration, but promoted apoptosis by suppressing ALK5 expression, reversing the effects of TGFβ signaling through the suppression of the SMAD‑dependent canonical pathway and promotion of the non‑canonical pathway. These effects were prevented by ALK5 overexpression. The inhibition of α‑ or β‑adrenergic receptors alleviated the NE‑mediated suppression of ALK5 expression. In conclusion, regional CSD protected rats from aortic aneurysm. NE inhibited SMAD2/3‑dependent TGFβ signaling by suppressing ALK5 expression, which may serve an important role in VSMC biological functions. Both α‑ and β‑adrenergic receptors were involved in the regulation of ALK5 expression by NE. Abnormal sympathetic innervation of the aorta may be used as a therapeutic target in aortic diseases.

Topics: Animals; Aorta; Aortic Aneurysm; Cell Line; Cell Proliferation; Male; Mice; Muscle, Smooth, Vascular; Norepinephrine; Rats, Sprague-Dawley; Receptor, Transforming Growth Factor-beta Type I; Transforming Growth Factor beta; Vascular Remodeling

Marfan syndrome (MFS) represents a genetic disorder with a range of clinical features, including proximal aortic aneurysms. Extensive research has revealed an abundance of transforming growth factor beta from a mutation in fibrillin-1 to be the key biochemical mechanism of aneurysm formation. Many important signaling pathways downstream of transforming growth factor beta have been further characterized. Our laboratory has previously demonstrated a unique murine model of MFS resulting in the accelerated formation of ascending aortic aneurysms and dilated cardiomyopathies. This study aims to characterize the relevance of this model to known signaling mechanisms in MFS.. Mice with MFS displayed downstream regulation in both the canonical (Smad2) and noncononical (extracellular signal-regulated kinases and P38) pathways characteristic of MFS. However, these downstream signals were exaggerated in the MFS mice supplemented with angiotensin II (accelerated model), matching the observed phenotypic severity of this model.. The murine MFS model depicted here accelerates ascending aortic aneurysm formation and cardiomyopathies via well-characterized MFS signaling cascades. The mechanistic relevance of the accelerated murine MFS model suggests that it could be an important tool in future studies hoping to characterize MFS signaling in an expedited experimental design.

Topics: Angiotensin II; Animals; Aorta; Aortic Aneurysm; Cardiomyopathies; Dilatation, Pathologic; Disease Models, Animal; Disease Progression; Extracellular Signal-Regulated MAP Kinases; Fibrillin-1; Genetic Predisposition to Disease; Heterozygote; Marfan Syndrome; Mice, Mutant Strains; Mutation; Myocardium; p38 Mitogen-Activated Protein Kinases; Phenotype; Phosphorylation; Signal Transduction; Smad2 Protein; Time Factors; Transforming Growth Factor beta

Formation of aortic aneurysms as a consequence of augmented transforming growth factor β (TGF-β) signaling and vascular smooth muscle cell (VSMC) dysfunction is a potentially lethal complication of Marfan syndrome (MFS). Here, we examined VSMC senescence in patients with MFS and explored the potential mechanisms that link VSMC senescence and TGF-β. Tissue was harvested from the ascending aorta of control donors and MFS patients, and VSMCs were isolated. Senescence-associated β-galactosidase (SA-β-gal) activity and expression of senescence-related proteins (p53, p21) were significantly higher in aneurysmal tissue from MFS patients than in healthy aortic tissue from control donors. Compared to control-VSMCs, MFS-VSMCs were larger with higher levels of both SA-β-gal activity and mitochondrial reactive oxygen species (ROS). In addition, TGF-β1 levels were much higher in MFS- than control-VSMCs. TGF-β1 induced VSMC senescence through excessive ROS generation. This effect was suppressed by Mito-tempo, a mitochondria-targeted antioxidant, or SC-514, a NF-κB inhibitor. This suggests TGF-β1 induces VSMC senescence through ROS-mediated activation of NF-κB signaling. It thus appears that a TGF-β1/ROS/NF-κB axis may mediate VSMC senescence and aneurysm formation in MFS patients. This finding could serve as the basis for a novel strategy for treating aortic aneurysm in MFS.

Topics: Aorta; Aortic Aneurysm; beta-Galactosidase; Cellular Senescence; Humans; Marfan Syndrome; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; NF-kappa B; Reactive Oxygen Species; Transforming Growth Factor beta

Diabetes is a negative risk factor for aortic aneurysm, but the underlying explanation for this phenomenon is unknown. We have previously demonstrated that cell division autoantigen 1 (CDA1), which enhances transforming growth factor-β signaling, is upregulated in diabetes. We hypothesized that CDA1 plays a key role in conferring the protective effect of diabetes against aortic aneurysms. Male wild-type, CDA1 knockout (KO), apolipoprotein E (ApoE) KO, and CDA1/ApoE double-KO (dKO) mice were rendered diabetic. Whereas aneurysms were not observed in diabetic ApoE KO and wild-type mice, 40% of diabetic dKO mice developed aortic aneurysms. These aneurysms were associated with attenuated aortic transforming growth factor-β signaling, reduced expression of various collagens, and increased aortic macrophage infiltration and matrix metalloproteinase 12 expression. In the well-characterized model of angiotensin II-induced aneurysm formation, concomitant diabetes reduced fatal aortic rupture and attenuated suprarenal aortic expansion, changes not seen in dKO mice. Furthermore, aortic CDA1 expression was downregulated ∼70% within biopsies from human abdominal aortic aneurysms. The identification that diabetes is associated with upregulation of vascular CDA1 and that CDA1 deletion in diabetic mice promotes aneurysm formation provides evidence that CDA1 plays a role in diabetes to reduce susceptibility to aneurysm formation.

Topics: Adult; Aged; Angiotensin II; Animals; Aortic Aneurysm; Aortic Aneurysm, Abdominal; Aortic Rupture; Autoantigens; Collagen; Diabetes Mellitus, Experimental; Female; Gene Expression Regulation; Humans; Macrophages; Male; Matrix Metalloproteinase 12; Mice; Mice, Knockout; Mice, Knockout, ApoE; Middle Aged; Severity of Illness Index; Signal Transduction; Smad3 Protein; Transforming Growth Factor beta; Vasoconstrictor Agents

The objective of the present study was to 1) analyze the ascending aortic proteome within a mouse model of Marfan syndrome (MFS; Fbn1

Topics: Animals; Aorta; Aortic Aneurysm; Cell Movement; Cell Proliferation; Cells, Cultured; Chromatography, High Pressure Liquid; Dilatation, Pathologic; Disease Models, Animal; Disease Progression; Fibrillin-1; Genetic Predisposition to Disease; Integrin beta3; Male; Marfan Syndrome; Mass Spectrometry; Mice, Inbred C57BL; Mice, Transgenic; Muscle, Smooth, Vascular; Mutation; Myocytes, Smooth Muscle; Phenotype; Phosphorylation; Protein Serine-Threonine Kinases; Proteomics; Rapamycin-Insensitive Companion of mTOR Protein; Signal Transduction; Time Factors; Transforming Growth Factor beta

Topics: Angiotensin II; Aorta, Abdominal; Aortic Aneurysm; Humans; Transforming Growth Factor beta; Transforming Growth Factors

Aortic aneurysms are life-threatening conditions with effective treatments mainly limited to emergency surgery or trans-arterial endovascular stent grafts, thus calling for the identification of specific molecular targets. Genetic studies have highlighted controversial roles of transforming growth factor β (TGF-β) signaling in aneurysm development. Here, we report on aneurysms developing in adult mice after smooth muscle cell (SMC)-specific inactivation of Smad4, an intracellular transducer of TGF-β. The results revealed that Smad4 inhibition activated interleukin-1β (IL-1β) in SMCs. This danger signal later recruited innate immunity in the adventitia through chemokine (C-C motif) ligand 2 (CCL2) and modified the mechanical properties of the aortic wall, thus favoring vessel dilation. SMC-specific Smad4 deletion in Il1r1- or Ccr2-null mice resulted in milder aortic pathology. A chronic treatment with anti-IL-1β antibody effectively hampered aneurysm development. These findings identify a mechanistic target for controlling the progression of aneurysms with compromised TGF-β signaling, such as those driven by SMAD4 mutations.

Topics: Animals; Aortic Aneurysm; Cells, Cultured; Chemokine CCL2; Interleukin-1beta; Mice; Myocytes, Smooth Muscle; NF-kappa B; Receptors, CCR2; Signal Transduction; Smad4 Protein; Tamoxifen; Transforming Growth Factor beta

Arterial remodeling participates pivotally in many diseases including arterial aneurysms. In this issue of Immunity, Da Ros et al. (2017) report that, in experimental aortic aneurysm formation, neutralization of interleukin-1β reduced arterial wall stiffness and hampered aneurysm development.

Topics: Animals; Aortic Aneurysm; Aortic Aneurysm, Abdominal; Cytokines; Disease Models, Animal; Interleukin-1beta; Mice; Mice, Inbred C57BL; Transforming Growth Factor beta

Ascending thoracic aortic aneurysm (ATAA) is a major cause of morbidity and mortality worldwide. The pathogenesis of medial degeneration of the aorta remains undefined. High-throughput secretome analysis by mass spectrometry may be useful to elucidate the molecular mechanisms involved in aneurysm formation as well as to identify biomarkers for early diagnosis or targets of therapy. The purpose of the present study was to analyze the secreted/released proteins from ATAA specimens of both tricuspid aortic valve (TAV) and bicuspid aortic valve (BAV) patients.. Aortic specimens were collected from patients undergoing elective surgery and requiring graft replacement of the ascending aorta. Each sample of the ascending aortic aneurysm, 4 BAV (3 males; aged 53.5±11.4 years) and 4 TAV (1 male; 78±7.5 years), was incubated for 24h in serum-free medium. Released proteins were digested with trypsin. Peptide mixtures were fractioned by nano-high performance liquid chromatography and analyzed by mass spectrometry. Following identification of differentially expressed proteins, quantitative real time polymerase chain reaction (qRT-PCR) analysis was performed.. The comparison between the proteins released from BAV and TAV aneurysmatic tissues showed significantly diverging expression fingerprints in the two groups of patients. Bioinformatics analysis revealed 38 differentially released proteins; in particular 7 proteins were down-regulated while 31 were up-regulated in BAV with respect to TAV. Most of the proteins that were up-released in BAV were related to the activation of transforming growth factor (TGF)-β signaling. Latent TGF-β binding protein 4 (LTBP4) exhibited one of the highest significant under-expressions (10-fold change) in BAV secretomes with respect to TAV. qRT-PCR analysis validated this significant difference at LTBP4 gene level (BAV: 1.03±0.9 vs TAV: 3.6±3.2; p<0.05).. Hypothesis-free secretome profiling clearly showed diverging expression fingerprints in the ATAA of TAV and BAV patients, confirming the crucial role of TGF-β signaling in modulating ATAA development in bicuspid patients.

Topics: Aged; Aorta; Aortic Aneurysm; Aortic Aneurysm, Thoracic; Aortic Valve; Bicuspid Aortic Valve Disease; Female; Heart Valve Diseases; Humans; Latent TGF-beta Binding Proteins; Male; Middle Aged; Signal Transduction; Transforming Growth Factor beta; Tricuspid Valve

Marfan syndrome (MFS) is a heritable connective tissue disorder caused by mutations in FBN1, which encodes the extracellular matrix protein fibrillin-1. To investigate the pathogenesis of aortic aneurysms in MFS, we generated a vascular model derived from human induced pluripotent stem cells (MFS-hiPSCs). Our MFS-hiPSC-derived smooth muscle cells (SMCs) recapitulated the pathology seen in Marfan aortas, including defects in fibrillin-1 accumulation, extracellular matrix degradation, transforming growth factor-β (TGF-β) signaling, contraction and apoptosis; abnormalities were corrected by CRISPR-based editing of the FBN1 mutation. TGF-β inhibition rescued abnormalities in fibrillin-1 accumulation and matrix metalloproteinase expression. However, only the noncanonical p38 pathway regulated SMC apoptosis, a pathological mechanism also governed by Krüppel-like factor 4 (KLF4). This model has enabled us to dissect the molecular mechanisms of MFS, identify novel targets for treatment (such as p38 and KLF4) and provided an innovative human platform for the testing of new drugs.

Topics: Aortic Aneurysm; Apoptosis; Fibrillin-1; Gene Expression Regulation; Humans; Induced Pluripotent Stem Cells; Kruppel-Like Factor 4; Kruppel-Like Transcription Factors; Marfan Syndrome; Models, Biological; Muscle, Smooth, Vascular; p38 Mitogen-Activated Protein Kinases; Signal Transduction; Transforming Growth Factor beta

Mutations in genes encoding proteins of the smooth muscle cell (SMC) contractile apparatus contribute to familial aortic aneurysms. To investigate the pathogenicity of these mutations, SMC are required. We demonstrate a novel method to generate SMC-like cells from human dermal fibroblasts by transdifferentiation to study the effect of variants in genes encoding proteins of the SMC contractile apparatus (ACTA2 and MYH11) in patients with aortic aneurysms. Dermal fibroblasts from seven healthy donors and cells from seven patients with MYH11 or ACTA2 variants were transdifferentiated into SMC-like cells within a 2-week duration using 5 ng/ml TGFβ1 on a scaffold containing collagen and elastin. The induced SMC were comparable to primary human aortic SMC in mRNA expression of SMC markers which was confirmed on the protein level by immunofluorescence quantification analysis and Western blotting. In patients with MYH11 or ACTA2 variants, the effect of intronic variants on splicing was demonstrated on the mRNA level in the induced SMC, allowing classification into pathogenic or nonpathogenic variants. In conclusion, direct conversion of human dermal fibroblasts into SMC-like cells is a highly efficient method to investigate the pathogenicity of variants in proteins of the SMC contractile apparatus.

Topics: Actins; Adult; Aged; Aortic Aneurysm; Cell Transdifferentiation; Cells, Cultured; Dermis; Extracellular Matrix Proteins; Female; Fibroblasts; Gene Expression; Humans; Male; Middle Aged; Mutation; Myocytes, Smooth Muscle; Myosin Heavy Chains; RNA Interference; RNA, Messenger; Transforming Growth Factor beta

Aneurysm-osteoarthritis syndrome characterized by unpredictable aortic aneurysm formation, is caused by SMAD3 mutations. SMAD3 is part of the SMAD2/3/4 transcription factor, essential for TGF-β-activated transcription. Although TGF-β-related gene mutations result in aneurysms, the underlying mechanism is unknown. Here, we examined aneurysm formation and progression in Smad3

Topics: Aneurysm; Animals; Aortic Aneurysm; Cell Proliferation; Connective Tissue; Disease Models, Animal; Echocardiography; Elastin; Extracellular Signal-Regulated MAP Kinases; Female; Immunohistochemistry; Inflammation; Male; Matrix Metalloproteinases; Mice; Mice, Knockout; Models, Biological; Molecular Imaging; Mortality; Muscle, Smooth, Vascular; Signal Transduction; Smad2 Protein; Smad3 Protein; Transcriptional Activation; Transforming Growth Factor beta; X-Ray Microtomography

Topics: Animals; Aortic Aneurysm; Humans; Mutation; Signal Transduction; Smad3 Protein; Transforming Growth Factor beta

Marfan's syndrome is characterized by the formation of ascending aortic aneurysms resulting from altered assembly of extracellular matrix microfibrils and chronic tissue growth factor (TGF)-β signaling. TGF-β is a potent regulator of the vascular smooth muscle cell (VSMC) phenotype. We hypothesized that as a result of the chronic TGF-β signaling, VSMC would alter their basal differentiation phenotype, which could facilitate the formation of aneurysms. This study explores whether Marfan's syndrome entails phenotypic alterations of VSMC and possible mechanisms at the subcellular level.. Immunohistochemical and Western blotting analyses of dilated aortas from Marfan patients showed overexpression of contractile protein markers (α-smooth muscle actin, smoothelin, smooth muscle protein 22 alpha, and calponin-1) and collagen I in comparison with healthy aortas. VSMC explanted from Marfan aortic aneurysms showed increased in vitro expression of these phenotypic markers and also of myocardin, a transcription factor essential for VSMC-specific differentiation. These alterations were generally reduced after pharmacological inhibition of the TGF-β pathway. Marfan VSMC in culture showed more robust actin stress fibers and enhanced RhoA-GTP levels, which was accompanied by increased focal adhesion components and higher nuclear localization of myosin-related transcription factor A. Marfan VSMC and extracellular matrix measured by atomic force microscopy were both stiffer than their respective controls.. In Marfan VSMC, both in tissue and in culture, there are variable TGF-β-dependent phenotypic changes affecting contractile proteins and collagen I, leading to greater cellular and extracellular matrix stiffness. Altogether, these alterations may contribute to the known aortic rigidity that precedes or accompanies Marfan's syndrome aneurysm formation.

Topics: Actins; Aorta; Aortic Aneurysm; Biomarkers; Calcium-Binding Proteins; Calponins; Case-Control Studies; Cell Differentiation; Cell Line, Tumor; Collagen Type I; Cytoskeletal Proteins; Dilatation, Pathologic; Focal Adhesions; Humans; Marfan Syndrome; Microfilament Proteins; Muscle Proteins; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Nuclear Proteins; Phenotype; rhoA GTP-Binding Protein; Signal Transduction; Stress Fibers; Trans-Activators; Transforming Growth Factor beta; Vascular Remodeling

Patients with bicuspid aortic valve (BAV) have an increased risk of developing ascending aortic aneurysms. Transforming growth factor-β (TGFβ) is a crucial factor of vascular remodeling, the impaired signaling of which can alter the structure and composition of the extracellular matrix. In this study, we analyzed the activity of TGFβ in aneurysmal and nonaneurysmal ascending aorta from BAV patients, using tricuspid aortic valve (TAV) patients as a reference group.. The response to exogenous TGFβ was analyzed with regard to gene expression in primary aortic smooth muscle cells that were isolated from 7 BAV and 5 TAV patients and in valve fibroblasts from 7 BAV and 8 TAV patients. The set of genes that were significantly changed by TGFβ (217 genes) was compared with gene expression profiles of the ascending aorta from BAV and TAV patients (139 arrays). By principle component analysis, based on the 217 genes, gene expression differed significantly in the intima/media region between aneurysmal BAV and TAV aortas, driven by the response in TAV patients. During aneurysm development the levels of phosphorylated SMADs and the availability of free TGFβ were lower in BAV patients compared with TAV. Confocal microscopy analysis showed a higher colocalization of latency associated peptide and latent TGFβ binding protein 3 in BAV aortas.. Our findings suggest that TGFβ activation during aneurysm formation is muted in patients with BAV, possibly as a result of an increased TGFβ sequestration in the extracellular space.

Topics: Adult; Aged; Aged, 80 and over; Aortic Aneurysm; Aortic Valve; Bicuspid Aortic Valve Disease; Cells, Cultured; Extracellular Matrix; Female; Gene Expression Profiling; Gene Expression Regulation; Heart Valve Diseases; Humans; Latent TGF-beta Binding Proteins; Male; Middle Aged; Phosphorylation; Principal Component Analysis; Protein Serine-Threonine Kinases; Receptor, Transforming Growth Factor-beta Type I; Receptors, Transforming Growth Factor beta; Signal Transduction; Smad Proteins; Transforming Growth Factor beta

Heart failure in diabetics is associated with cardiac hypertrophy, fibrosis and diastolic dysfunction. Activation of transforming growth factor-β/Smad3 signaling in the diabetic myocardium may mediate fibrosis and diastolic heart failure, while preserving matrix homeostasis. We hypothesized that Smad3 may play a key role in the pathogenesis of cardiovascular remodeling associated with diabetes mellitus and obesity.. We generated leptin-resistant db/db Smad3 null mice and db/db Smad3+/- animals. Smad3 haploinsufficiency did not affect metabolic function in db/db mice, but protected from myocardial diastolic dysfunction, while causing left ventricular chamber dilation. Improved cardiac compliance and chamber dilation in db/db Smad3+/- animals were associated with decreased cardiomyocyte hypertrophy, reduced collagen deposition, and accentuated matrix metalloproteinase activity. Attenuation of hypertrophy and fibrosis in db/db Smad3+/- hearts was associated with reduced myocardial oxidative and nitrosative stress. db/db Smad3 null mice had reduced weight gain and decreased adiposity associated with attenuated insulin resistance, but also exhibited high early mortality, in part, because of spontaneous rupture of the ascending aorta. Ultrasound studies showed that both lean and obese Smad3 null animals had significant aortic dilation. Aortic dilation in db/db Smad3 null mice occurred despite reduced hypertension and was associated with perturbed matrix balance in the vascular wall.. Smad3 mediates diabetic cardiac hypertrophy, fibrosis, and diastolic dysfunction, while preserving normal cardiac geometry and maintaining the integrity of the vascular wall.

Topics: Animals; Aorta; Aortic Aneurysm; Aortic Rupture; Cardiomegaly; Diabetic Cardiomyopathies; Dilatation, Pathologic; Disease Models, Animal; Female; Fibrosis; Male; Matrix Metalloproteinases; Mice, Inbred C57BL; Mice, Knockout; Myocardium; Obesity; Signal Transduction; Smad3 Protein; Time Factors; Transforming Growth Factor beta; Vascular Remodeling; Ventricular Dysfunction, Left; Ventricular Remodeling

Several ultrasound-based methods are currently used to assess aortic diameter, circumferential strain and stiffness in mice, but none of them is flawless and a gold standard is lacking. We aimed to assess the validity and sensitivity of these methods in control animals and animals developing dissecting abdominal aortic aneurysm.. We first compared systolic and diastolic diameters as well as local circumferential strains obtained in 47 Angiotensin II-infused ApoE(-/-) mice with three different techniques (BMode, short axis MMode, long axis MMode), at two different abdominal aortic locations (supraceliac and paravisceral), and at three different time points of abdominal aneurysm formation (baseline, 14 days and 28 days). We found that short axis BMode was preferred to assess diameters, but should be avoided for strains. Short axis MMode gave good results for diameters but high standard deviations for strains. Long axis MMode should be avoided for diameters, and was comparable to short axis MMode for strains. We then compared pulse wave velocity measurements using global, ultrasound-based transit time or regional, pressure-based transit time in 10 control and 20 angiotensin II-infused, anti-TGF-Beta injected C57BL/6 mice. Both transit-time methods poorly correlated and were not able to detect a significant difference in PWV between controls and aneurysms. However, a combination of invasive pressure and MMode diameter, based on radio-frequency data, detected a highly significant difference in local aortic stiffness between controls and aneurysms, with low standard deviation.. In small animal ultrasound the short axis view is preferred over the long axis view to measure aortic diameters, local methods are preferred over transit-time methods to measure aortic stiffness, invasive pressure-diameter data are preferred over non-invasive strains to measure local aortic stiffness, and the use of radiofrequency data improves the accuracy of diameter, strain as well as stiffness measurements.

Topics: Angiotensin II; Animals; Antibodies; Aorta; Aortic Aneurysm; Male; Mice; Mice, Knockout; Transforming Growth Factor beta; Ultrasonography; Vascular Stiffness

Loeys-Dietz syndrome (LDS) is a connective tissue disorder that is characterized by skeletal abnormalities, craniofacial malformations, and a high predisposition for aortic aneurysm. In this issue of the JCI, Gallo et al. developed transgenic mouse strains harboring missense mutations in the genes encoding type I or II TGF-β receptors. These mice exhibited several LDS-associated phenotypes. Despite being functionally defective, the mutated receptors enhanced TGF-β signaling in vivo, inferred by detection of increased levels of phosphorylated Smad2. Aortic aneurysms in these LDS mice were ablated by treatment with the Ang II type 1 (AT1) receptor antagonist losartan. The results from this study will foster further interest into the potential therapeutic implications of AT1 receptor antagonists.

Topics: Angiotensin II; Animals; Aortic Aneurysm; Female; Humans; Loeys-Dietz Syndrome; Transforming Growth Factor beta

Loeys-Dietz syndrome (LDS) is a connective tissue disorder that is characterized by a high risk for aneurysm and dissection throughout the arterial tree and phenotypically resembles Marfan syndrome. LDS is caused by heterozygous missense mutations in either TGF-β receptor gene (TGFBR1 or TGFBR2), which are predicted to result in diminished TGF-β signaling; however, aortic surgical samples from patients show evidence of paradoxically increased TGF-β signaling. We generated 2 knockin mouse strains with LDS mutations in either Tgfbr1 or Tgfbr2 and a transgenic mouse overexpressing mutant Tgfbr2. Knockin and transgenic mice, but not haploinsufficient animals, recapitulated the LDS phenotype. While heterozygous mutant cells had diminished signaling in response to exogenous TGF-β in vitro, they maintained normal levels of Smad2 phosphorylation under steady-state culture conditions, suggesting a chronic compensation. Analysis of TGF-β signaling in the aortic wall in vivo revealed progressive upregulation of Smad2 phosphorylation and TGF-β target gene output, which paralleled worsening of aneurysm pathology and coincided with upregulation of TGF-β1 ligand expression. Importantly, suppression of Smad2 phosphorylation and TGF-β1 expression correlated with the therapeutic efficacy of the angiotensin II type 1 receptor antagonist losartan. Together, these data suggest that increased TGF-β signaling contributes to postnatal aneurysm progression in LDS.

Topics: Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Animals; Aorta; Aortic Aneurysm; Cells, Cultured; Disease Progression; Female; Haploinsufficiency; Humans; Loeys-Dietz Syndrome; Losartan; Mice; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Transgenic; Mutation, Missense; Myocytes, Smooth Muscle; Phenotype; Protein Serine-Threonine Kinases; Receptor, Transforming Growth Factor-beta Type I; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta; Signal Transduction; Smad2 Protein; Transforming Growth Factor beta

Acute aortic dissection (AAD) is caused by the disruption of intimomedial layer of the aortic walls, which is immediately life-threatening. Although recent studies indicate the importance of proinflammatory response in pathogenesis of AAD, the mechanism to keep the destructive inflammatory response in check is unknown. Here, we report that induction of tenascin-C (TNC) is a stress-evoked protective mechanism against the acute hemodynamic and humoral stress in aorta. Periaortic application of CaCl₂ caused stiffening of abdominal aorta, which augmented the hemodynamic stress and TNC induction in suprarenal aorta by angiotensin II infusion. Deletion of Tnc gene rendered mice susceptible to AAD development upon the aortic stress, which was accompanied by impaired TGFβ signaling, insufficient induction of extracellular matrix proteins and exaggerated proinflammatory response. Thus, TNC works as a stress-evoked molecular damper to maintain the aortic integrity under the acute stress.

Topics: Angiotensin II; Animals; Aorta; Aortic Aneurysm; Calcium Chloride; Cells, Cultured; Disease Models, Animal; Gene Expression Profiling; Hemodynamics; Mice; Mice, Knockout; Myocytes, Smooth Muscle; Signal Transduction; Tenascin; Transforming Growth Factor beta

An ascending aortic aneurysm is a common and very much unwelcome diagnosis that has never been associated with anything positive. We believe, however, that there actually is a silver lining to this disease: aortic root and ascending aortic aneurysms actually protect against atherosclerosis. We have found that patients with ascending aneurysms have both decreased arterial calcification and carotid intima-media thickness, late and early indicators of atherosclerosis, respectively. In addition to these clinical data, we also found data regarding molecular mechanisms, genetic studies, and pharmacologic evidence that corroborate our clinical findings, in particular, evidence regarding matrix metalloproteinases and transforming growth factor-β pathways. In this article, we lay out the evidence that has been accruing for the protective effect of ascending aneurysms against atherosclerosis.

Topics: Aortic Aneurysm; Atherosclerosis; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Matrix Metalloproteinases; Metabolic Networks and Pathways; Transforming Growth Factor beta

In this study we set out to investigate the clinically observed relationship between chronic obstructive pulmonary disease (COPD) and aortic aneurysms. We tested the hypothesis that an inherited deficiency of connective tissue might play a role in the combined development of pulmonary emphysema and vascular disease.. We first determined the prevalence of chronic obstructive pulmonary disease in a clinical cohort of aortic aneurysms patients and arterial occlusive disease patients. Subsequently, we used a combined approach comprising pathological, functional, molecular imaging, immunological and gene expression analysis to reveal the sequence of events that culminates in pulmonary emphysema in aneurysmal Fibulin-4 deficient (Fibulin-4(R)) mice.. Here we show that COPD is significantly more prevalent in aneurysm patients compared to arterial occlusive disease patients, independent of smoking, other clinical risk factors and inflammation. In addition, we demonstrate that aneurysmal Fibulin-4(R/R) mice display severe developmental lung emphysema, whereas Fibulin-4(+/R) mice acquire alveolar breakdown with age and upon infectious stress. This vicious circle is further exacerbated by the diminished antiprotease capacity of the lungs and ultimately results in the development of pulmonary emphysema.. Our experimental data identify genetic susceptibility to extracellular matrix degradation and secondary inflammation as the common mechanisms in both COPD and aneurysm formation.

Topics: Aged; alpha 1-Antitrypsin; Animals; Aorta; Aortic Aneurysm; Cohort Studies; Disease Susceptibility; Down-Regulation; Extracellular Matrix; Extracellular Matrix Proteins; Female; Humans; Lipopolysaccharides; Lung; Male; Matrix Metalloproteinases; Mice; Neutrophils; Pancreatic Elastase; Pulmonary Alveoli; Pulmonary Emphysema; Signal Transduction; Transforming Growth Factor beta

Neural crest cells (NCCs) participate in the remodeling of the cardiac outflow tract and pharyngeal arch arteries during cardiovascular development. Integrin-linked kinase (ILK) is a serine/threonine kinase and a major regulator of integrin signaling. It links integrins to the actin cytoskeleton and recruits other adaptor molecules into a large complex to regulate actin dynamics and integrin function. Using the Cre-lox system, we deleted Ilk from NCCs of mice to investigate its role in NCC morphogenesis. The resulting mutants developed a severe aneurysmal arterial trunk that resulted in embryonic lethality during late gestation. Ilk mutants showed normal cardiac NCC migration but reduced differentiation into smooth muscle within the aortic arch arteries and the outflow tract. Within the conotruncal cushions, Ilk-deficient NCCs exhibited disorganization of F-actin stress fibers and a significantly rounder morphology, with shorter cellular projections. Additionally, absence of ILK resulted in reduced in vivo phosphorylation of Smad3 in NCCs, which correlated with reduced αSMA levels. Our findings resemble those seen in Pinch1 and β1 integrin conditional mutant mice, and therefore support that, in neural crest-derived cells, ILK and Pinch1 act as cytoplasmic effectors of β1 integrin in a pathway that protects against aneurysms. In addition, our conditional Ilk mutant mice might prove useful as a model to study aortic aneurysms caused by reduced Smad3 signaling, as occurs in the newly described aneurysms-osteoarthritis syndrome, for example.

Topics: Actin Cytoskeleton; Animals; Aorta, Thoracic; Aortic Aneurysm; Cardiovascular Abnormalities; Cell Differentiation; Cell Movement; Cell Proliferation; Craniofacial Abnormalities; Embryo Loss; Embryo, Mammalian; Gene Deletion; Integrases; Mice; Mice, Mutant Strains; Morphogenesis; Neural Crest; Organ Specificity; Phenotype; Protein Serine-Threonine Kinases; Signal Transduction; Smad3 Protein; Transforming Growth Factor beta; Wnt Proteins

Marfan syndrome (MFS) is a systemic connective tissue disorder notable for the development of aortic root aneurysms and the subsequent life-threatening complications of aortic dissection and rupture. Underlying fibrillin-1 gene mutations cause increased transforming growth factor-β (TGF-β) signaling. Although TGF-β blockade prevents aneurysms in MFS mouse models, the mechanisms through which excessive TGF-β causes aneurysms remain ill-defined.. We investigated the role of microRNA-29b (miR-29b) in aneurysm formation in MFS.. Using quantitative polymerase chain reaction, we discovered that miR-29b, a microRNA regulating apoptosis and extracellular matrix synthesis/deposition genes, is increased in the ascending aorta of Marfan (Fbn1(C1039G/+)) mice. Increased apoptosis, assessed by increased cleaved caspase-3 and caspase-9, enhanced caspase-3 activity, and decreased levels of the antiapoptotic proteins, Mcl-1 and Bcl-2, were found in the Fbn1(C1039G/+) aorta. Histological evidence of decreased and fragmented elastin was observed exclusively in the Fbn1(C1039G/+) ascending aorta in association with repressed elastin mRNA and increased matrix metalloproteinase-2 expression and activity, both targets of miR-29b. Evidence of decreased activation of nuclear factor κB, a repressor of miR-29b, and a factor suppressed by TGF-β, was also observed in Fbn1(C1039G/+) aorta. Furthermore, administration of a nuclear factor κB inhibitor increased miR-29b levels, whereas TGF-β blockade or losartan effectively decreased miR-29b levels in Fbn1(C1039G/+) mice. Finally, miR-29b blockade by locked nucleic acid antisense oligonucleotides prevented early aneurysm development, aortic wall apoptosis, and extracellular matrix deficiencies.. We identify increased miR-29b expression as key to the pathogenesis of early aneurysm development in MFS by regulating aortic wall apoptosis and extracellular matrix abnormalities.

Topics: Age Factors; Angiotensin II Type 1 Receptor Blockers; Animals; Aorta; Aortic Aneurysm; Apoptosis; Apoptosis Regulatory Proteins; Cells, Cultured; Disease Models, Animal; Elastin; Female; Fibrillin-1; Fibrillins; Genetic Therapy; Losartan; Male; Marfan Syndrome; Matrix Metalloproteinase 2; Mice; Mice, Inbred C57BL; Mice, Transgenic; Microfilament Proteins; MicroRNAs; NF-kappa B; Oligonucleotides, Antisense; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; Transforming Growth Factor beta; Up-Regulation

To assess the effect of Loeys-Dietz syndrome (LDS) mutations affecting TGFΒR1 a selection of seven disease-associated amino acid substitutions were introduced into wild type TGFβR1 and constitutively active TGFβR1(T204D). Receptor function was tested by co-transfection with a luciferase reporter or EGFP-tagged SMAD2 in HEK293 cells. All of the mutations were found to be inactivating for canonical TGF-β signaling. Differences in residual activity were not found to correlate with disease subtype. In co-transfection experiments with equal amounts wild-type receptor, the LDS mutations were found to confer a modest dominant negative effect. These results are discussed in relation to LDS and the related Marfan syndrome.

Topics: Aortic Aneurysm; Genes, Dominant; HEK293 Cells; Humans; Loeys-Dietz Syndrome; Marfan Syndrome; Mutation; Phenotype; Phosphorylation; Protein Serine-Threonine Kinases; Receptor, Transforming Growth Factor-beta Type I; Receptors, Transforming Growth Factor beta; Signal Transduction; Smad Proteins; Transfection; Transforming Growth Factor beta

Elevated transforming growth factor (TGF)-β signaling has been implicated in the pathogenesis of syndromic presentations of aortic aneurysm, including Marfan syndrome (MFS) and Loeys-Dietz syndrome (LDS). However, the location and character of many of the causal mutations in LDS intuitively imply diminished TGF-β signaling. Taken together, these data have engendered controversy regarding the specific role of TGF-β in disease pathogenesis. Shprintzen-Goldberg syndrome (SGS) has considerable phenotypic overlap with MFS and LDS, including aortic aneurysm. We identified causative variation in ten individuals with SGS in the proto-oncogene SKI, a known repressor of TGF-β activity. Cultured dermal fibroblasts from affected individuals showed enhanced activation of TGF-β signaling cascades and higher expression of TGF-β-responsive genes relative to control cells. Morpholino-induced silencing of SKI paralogs in zebrafish recapitulated abnormalities seen in humans with SGS. These data support the conclusions that increased TGF-β signaling is the mechanism underlying SGS and that high signaling contributes to multiple syndromic presentations of aortic aneurysm.

Topics: Animals; Aortic Aneurysm; Arachnodactyly; Cells, Cultured; Craniosynostoses; DNA-Binding Proteins; Fibroblasts; Humans; Loeys-Dietz Syndrome; Marfan Syndrome; Mice; Mutation; Phenotype; Phosphorylation; Proto-Oncogene Mas; Proto-Oncogene Proteins; Signal Transduction; Transforming Growth Factor beta; Zebrafish

Thoracic aortic aneurysms and dissections are a main feature of connective tissue disorders, such as Marfan syndrome and Loeys-Dietz syndrome. We delineated a new syndrome presenting with aneurysms, dissections and tortuosity throughout the arterial tree in association with mild craniofacial features and skeletal and cutaneous anomalies. In contrast with other aneurysm syndromes, most of these affected individuals presented with early-onset osteoarthritis. We mapped the genetic locus to chromosome 15q22.2-24.2 and show that the disease is caused by mutations in SMAD3. This gene encodes a member of the TGF-β pathway that is essential for TGF-β signal transmission. SMAD3 mutations lead to increased aortic expression of several key players in the TGF-β pathway, including SMAD3. Molecular diagnosis will allow early and reliable identification of cases and relatives at risk for major cardiovascular complications. Our findings endorse the TGF-β pathway as the primary pharmacological target for the development of new treatments for aortic aneurysms and osteoarthritis.

Topics: Age of Onset; Aorta, Thoracic; Aortic Aneurysm; Chromosomes, Human, Pair 15; Family Health; Female; Humans; Immunohistochemistry; Male; Mutation; Osteoarthritis; Radiography; Signal Transduction; Smad3 Protein; Syndrome; Transforming Growth Factor beta

Topics: Animals; Aortic Aneurysm; Clinical Trials as Topic; Extracellular Signal-Regulated MAP Kinases; Humans; Losartan; MAP Kinase Signaling System; Marfan Syndrome; Mice; Protein Kinase Inhibitors; Signal Transduction; Transforming Growth Factor beta

Transforming growth factor-β (TGFβ) signaling drives aneurysm progression in multiple disorders, including Marfan syndrome (MFS), and therapies that inhibit this signaling cascade are in clinical trials. TGFβ can stimulate multiple intracellular signaling pathways, but it is unclear which of these pathways drives aortic disease and, when inhibited, which result in disease amelioration. Here we show that extracellular signal-regulated kinase (ERK) 1 and 2 and Smad2 are activated in a mouse model of MFS, and both are inhibited by therapies directed against TGFβ. Whereas selective inhibition of ERK1/2 activation ameliorated aortic growth, Smad4 deficiency exacerbated aortic disease and caused premature death in MFS mice. Smad4-deficient MFS mice uniquely showed activation of Jun N-terminal kinase-1 (JNK1), and a JNK antagonist ameliorated aortic growth in MFS mice that lacked or retained full Smad4 expression. Thus, noncanonical (Smad-independent) TGFβ signaling is a prominent driver of aortic disease in MFS mice, and inhibition of the ERK1/2 or JNK1 pathways is a potential therapeutic strategy for the disease.

Topics: Animals; Anthracenes; Aorta; Aortic Aneurysm; Diphenylamine; Disease Models, Animal; Disease Progression; Enzyme Activation; Losartan; MAP Kinase Signaling System; Marfan Syndrome; Mice; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinase 8; Protein Kinase Inhibitors; Smad2 Protein; Smad4 Protein; Sulfonamides; Transforming Growth Factor beta

Angiotensin II (AngII) mediates progression of aortic aneurysm, but the relative contribution of its type 1 (AT1) and type 2 (AT2) receptors remains unknown. We show that loss of AT2 expression accelerates the aberrant growth and rupture of the aorta in a mouse model of Marfan syndrome (MFS). The selective AT1 receptor blocker (ARB) losartan abrogated aneurysm progression in the mice; full protection required intact AT2 signaling. The angiotensin-converting enzyme inhibitor (ACEi) enalapril, which limits signaling through both receptors, was less effective. Both drugs attenuated canonical transforming growth factor-β (TGFβ) signaling in the aorta, but losartan uniquely inhibited TGFβ-mediated activation of extracellular signal-regulated kinase (ERK), by allowing continued signaling through AT2. These data highlight the protective nature of AT2 signaling and potentially inform the choice of therapies in MFS and related disorders.

Topics: Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Animals; Aorta; Aortic Aneurysm; Aortic Rupture; Disease Models, Animal; Disease Progression; Enalapril; Losartan; MAP Kinase Signaling System; Marfan Syndrome; Mice; Mice, Knockout; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Receptor, Angiotensin, Type 2; Signal Transduction; Transforming Growth Factor beta

Topics: Aortic Aneurysm; Aortic Dissection; Biomarkers; Humans; Marfan Syndrome; Transforming Growth Factor beta

Medial degeneration is a key feature of aneurysm disease and aortic dissection. In a murine aneurysm model we investigated the structural and functional characteristics of aortic wall degeneration in adult fibulin-4 deficient mice and the potential therapeutic role of the angiotensin (Ang) II type 1 (AT(1)) receptor antagonist losartan in preventing aortic media degeneration. Adult mice with 2-fold (heterozygous Fibulin-4(+/R)) and 4-fold (homozygous Fibulin-4(R/R)) reduced expression of fibulin-4 displayed the histological features of cystic media degeneration as found in patients with aneurysm or dissection, including elastin fiber fragmentation, loss of smooth muscle cells, and deposition of ground substance in the extracellular matrix of the aortic media. The aortic contractile capacity, determined by isometric force measurements, was diminished, and was associated with dysregulation of contractile genes as shown by aortic transcriptome analysis. These structural and functional alterations were accompanied by upregulation of TGF-β signaling in aortas from fibulin-4 deficient mice, as identified by genome-scaled network analysis as well as by immunohistochemical staining for phosphorylated Smad2, an intracellular mediator of TGF-β. Tissue levels of Ang II, a regulator of TGF-β signaling, were increased. Prenatal treatment with the AT(1) receptor antagonist losartan, which blunts TGF-β signaling, prevented elastic fiber fragmentation in the aortic media of newborn Fibulin-4(R/R) mice. Postnatal losartan treatment reduced haemodynamic stress and improved lifespan of homozygous knockdown fibulin-4 animals, but did not affect aortic vessel wall structure. In conclusion, the AT(1) receptor blocker losartan can prevent aortic media degeneration in a non-Marfan syndrome aneurysm mouse model. In established aortic aneurysms, losartan does not affect aortic architecture, but does improve survival. These findings may extend the potential therapeutic application of inhibitors of the renin-angiotensin system to the preventive treatment of aneurysm disease.

Topics: Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Animals; Animals, Newborn; Aorta, Thoracic; Aortic Aneurysm; Extracellular Matrix Proteins; Female; Humans; Immunohistochemistry; In Vitro Techniques; Losartan; Male; Mice; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Knockout; Oligonucleotide Array Sequence Analysis; Phenylephrine; Pregnancy; Receptor, Angiotensin, Type 1; Smad2 Protein; Transcriptome; Transforming Growth Factor beta; Vasoconstriction; Vasoconstrictor Agents

Topics: Aortic Aneurysm; Genetic Markers; Humans; Marfan Syndrome; Transforming Growth Factor beta

We have previously shown that the angiotensin-converting enzyme (ACE) inhibitor perindopril reduced aortic diameter by 3-7mm in Marfan syndrome (MFS) patients. Excessive signalling by the transforming growth factor-beta (TGF-beta) has been implicated in the development of aortic dilatation. We hypothesised that reduction in aortic diameter would correlate with reduction in plasma TGF-beta and matrix metalloproteinase (MMP) levels.. 17 MFS patients (aged 33+/-5 (mean+/-SD)) on standard beta-blocker therapy were randomised to also receive perindopril (n=10) or placebo (n=7) for 24 weeks in a double blind study. Aortic root diameters were assessed at four sites via transthoracic echocardiography. Venous blood samples were analysed for latent and active TGF-beta, MMP-2 and MMP-3 levels.. Perindopril significantly reduced aortic root diameters relative to placebo in both end-systole and end-diastole (by 1.2-3mm/m(2), p<0.001). In addition, compared to placebo perindopril significantly reduced latent TGF-beta levels by 14.0+/-4.5ng/ml (p=0.01), active TGF-beta levels by 4+/-1ng/ml (p=0.02), MMP-2 levels by 22+/-6ng/ml (p<0.001), and MMP-3 levels by 5+/-1ng/ml (p<0.001). There were moderately strong correlations between the pre/post intervention change in aortic diameters and the change in both latent (r=0.49-0.76, p=0.001-0.04) and active TGF-beta (r=0.59-0.73, p=0.002-0.02), MMP-2 (r=0.63-0.75, p=0.001-0.007), and MMP-3 plasma levels (r=0.81-0.83, p<0.0001).. Plasma TGF-beta, MMP-2 and MMP-3 should be further explored in longitudinal trials as potential prognostic indicators of progression of aortic dilatation and response to therapy in MFS.

Topics: Adult; Angiotensin-Converting Enzyme Inhibitors; Aortic Aneurysm; Biomarkers; Female; Humans; Male; Marfan Syndrome; Matrix Metalloproteinase 2; Matrix Metalloproteinase 3; Matrix Metalloproteinase Inhibitors; Perindopril; Randomized Controlled Trials as Topic; Transforming Growth Factor beta

S100A12 is a small calcium binding protein that is a ligand of RAGE (receptor for advanced glycation end products). RAGE has been extensively implicated in inflammatory states such as atherosclerosis, but the role of S100A12 as its ligand is less clear.. To test the role of S100A12 in vascular inflammation, we generated and analyzed mice expressing human S100A12 in vascular smooth muscle under control of the smooth muscle 22alpha promoter because S100A12 is not present in mice.. Transgenic mice displayed pathological vascular remodeling with aberrant thickening of the aortic media, disarray of elastic fibers, and increased collagen deposition, together with increased latent matrix metalloproteinase-2 protein and reduction in smooth muscle stress fibers leading to a progressive dilatation of the aorta. In primary aortic smooth muscle cell cultures, we found that S100A12 mediates increased interleukin-6 production, activation of transforming growth factor beta pathways and increased metabolic activity with enhanced oxidative stress. To correlate our findings to human aortic aneurysmal disease, we examined S100A12 expression in aortic tissue from patients with thoracic aortic aneurysm and found increased S100A12 expression in vascular smooth muscle cells.. S100A12 expression is sufficient to activate pathogenic pathways through the modulation of oxidative stress, inflammation and vascular remodeling in vivo.

Topics: Animals; Aortic Aneurysm; Cells, Cultured; Collagen; Elastic Tissue; Humans; Interleukin-6; Mice; Mice, Transgenic; Muscle, Smooth, Vascular; Oxidative Stress; Receptor for Advanced Glycation End Products; Receptors, Immunologic; S100 Proteins; S100A12 Protein; Stress Fibers; Transforming Growth Factor beta; Vasculitis

Topics: Animals; Aortic Aneurysm; Cells, Cultured; Collagen; Elastic Tissue; Humans; Interleukin-6; Mice; Mice, Transgenic; Muscle, Smooth, Vascular; Oxidative Stress; Receptor for Advanced Glycation End Products; Receptors, Immunologic; S100 Proteins; S100A12 Protein; Stress Fibers; Transforming Growth Factor beta; Vasculitis

TGF-beta regulates many aspects of cellular performance relevant to tissue morphogenesis and homeostasis. Postnatal perturbation of TGF-beta signaling contributes to the pathogenesis of many disease states, as recently exemplified through the study of Marfan syndrome (MFS), including aortic aneurysm and skeletal muscle myopathy. Heterogeneity in the regulation and consequences of TGF-beta signaling, amplified in the context of disease, has engendered confusion and controversy regarding its utility as a therapeutic target. Three studies recently published in the JCI, including one in this issue, underscore the complexity of this subject. Heydemann and colleagues implicate dimorphic variation in latent TGF-beta-binding protein 4 (LTBP4), a regulator of TGF-beta bioavailability and activation, as a modifier of muscular dystrophy in gamma-sarcoglycan-deficient mice. In contrast to experience with ascending aortic aneurysm in MFS, Wang and colleagues show that systemic abrogation of TGF-beta signaling worsens (rather than attenuates) Ang II-induced abdominal aortic aneurysm progression in mice. Tieu and colleagues define alterations in the regulation of vascular inflammation in the pathogenesis of Ang II-induced aneurysm and dissection in mice, which may help shed some light on this apparent paradox.

Topics: Animals; Aortic Aneurysm; Child; Disease Models, Animal; Humans; Latent TGF-beta Binding Proteins; Male; Marfan Syndrome; Mice; Muscle Fibers, Skeletal; Muscle, Skeletal; Muscular Diseases; Muscular Dystrophies; Signal Transduction; Transforming Growth Factor beta

Fibulin-4 is a member of the fibulin family, a group of extracellular matrix proteins prominently expressed in medial layers of large veins and arteries. Involvement of the FBLN4 gene in cardiovascular pathology was shown in a murine model and in three patients affected with cutis laxa in association with systemic involvement. To elucidate the contribution of FBLN4 in human disease, we investigated two cohorts of patients. Direct sequencing of 17 patients with cutis laxa revealed no FBLN4 mutations. In a second group of 22 patients presenting with arterial tortuosity, stenosis and aneurysms, FBLN4 mutations were identified in three patients, two homozygous missense mutations (p.Glu126Lys and p.Ala397Thr) and compound heterozygosity for missense mutation p.Glu126Val and frameshift mutation c.577delC. Immunoblotting analysis showed a decreased amount of fibulin-4 protein in the fibroblast culture media of two patients, a finding sustained by diminished fibulin-4 in the extracellular matrix of the aortic wall on immunohistochemistry. pSmad2 and CTGF immunostaining of aortic and lung tissue revealed an increase in transforming growth factor (TGF)beta signaling. This was confirmed by pSmad2 immunoblotting of fibroblast cultures. In conclusion, patients with recessive FBLN4 mutations are predominantly characterized by aortic aneurysms, arterial tortuosity and stenosis. This confirms the important role of fibulin-4 in vascular elastic fiber assembly. Furthermore, we provide the first evidence for the involvement of altered TGFbeta signaling in the pathogenesis of FBLN4 mutations in humans.

Topics: Aortic Aneurysm; Aortic Diseases; Cardiovascular Diseases; Child; Constriction, Pathologic; Cutis Laxa; Elastic Tissue; Extracellular Matrix Proteins; Female; Frameshift Mutation; Humans; Infant; Infant, Newborn; Male; Mutation, Missense; Signal Transduction; Skin; Transforming Growth Factor beta; Young Adult

Reduced bone mineral density (osteopenia) is a poorly characterized manifestation of pediatric and adult patients afflicted with Marfan syndrome (MFS), a multisystem disorder caused by structural or quantitative defects in fibrillin-1 that perturb tissue integrity and TGFβ bioavailability. Here we report that mice with progressively severe MFS (Fbn1(mgR/mgR) mice) develop osteopenia associated with normal osteoblast differentiation and bone formation. In vivo and ex vivo experiments, respectively, revealed that adult Fbn1(mgR/mgR) mice respond more strongly to locally induced osteolysis and that Fbn1(mgR/mgR) osteoblasts stimulate pre-osteoclast differentiation more than wild-type cells. Greater osteoclastogenic potential of mutant osteoblasts was largely attributed to Rankl up-regulation secondary to improper TGFβ activation and signaling. Losartan treatment, which lowers TGFβ signaling and restores aortic wall integrity in mice with mild MFS, did not mitigate bone loss in Fbn1(mgR/mgR) mice even though it ameliorated vascular disease. Conversely, alendronate treatment, which restricts osteoclast activity, improved bone quality but not aneurysm progression in Fbn1(mgR/mgR) mice. Taken together, our findings shed new light on the pathogenesis of osteopenia in MFS, in addition to arguing for a multifaceted treatment strategy in this congenital disorder of the connective tissue.

Topics: Alendronate; Animals; Aorta; Aortic Aneurysm; Bone Diseases, Metabolic; Bone Morphogenetic Proteins; Bone Resorption; Disease Models, Animal; Fibrillin-1; Fibrillins; Losartan; Marfan Syndrome; Mice; Mice, Inbred C57BL; Microfilament Proteins; Mutation; Osteoblasts; Osteoclasts; Osteogenesis; Spine; Tomography, X-Ray Computed; Transforming Growth Factor beta

Loeys-Dietz syndrome is a recently-characterised genetic disorder with an autosomal-dominant inheritance due to mutations in the transforming growth factor beta-receptor Type 1 or Type 2 genes. We present a Chinese female neonate with genetically-confirmed Loeys-Dietz syndrome, cleft palate, hypertelorism, and an early dilatation of the aortic root and ascending aorta. This syndrome is associated with an aggressive arteriopathy, with an increased risk of dissection and rupture. Early diagnosis, close monitoring and early surgery may prolong the life in affected individuals. Losartan is an emerging therapy that may help slow down the rate of arterial dilatation.

Topics: Anti-Arrhythmia Agents; Aortic Aneurysm; Echocardiography; Female; Humans; Infant, Newborn; Loeys-Dietz Syndrome; Losartan; Marfan Syndrome; Risk; Time Factors; Transforming Growth Factor beta

The Fibulins are a 6-member protein family hypothesized to function as intermolecular bridges that stabilize the organization of extracellular matrix structures. Here, we show that reduced expression of Fibulin-4 leads to aneurysm formation, dissection of the aortic wall and cardiac abnormalities. Fibulin-4 knockdown mice with a hypomorphic expression allele arose from targeted disruption of the adjacent Mus81 endonuclease gene. Mice homozygous for the Fibulin-4 reduced expression allele (Fibulin-4(R/R)) show dilatation of the ascending aorta and a tortuous and stiffened aorta, resulting from disorganized elastic fiber networks. They display thickened aortic valvular leaflets that are associated with aortic valve stenosis and insufficiency. Strikingly, already a modest reduction in expression of Fibulin-4 in the heterozygous Fibulin-4(+/R) mice occasionally resulted in small aneurysm formation. To get insight into the underlying molecular pathways involved in aneurysm formation and response to aortic failure, we determined the aorta transcriptome of Fibulin-4(+/R) and Fibulin-4(R/R) animals and identified distinct and overlapping biological processes that were significantly overrepresented including cytoskeleton organization, cell adhesion, apoptosis and several novel gene targets. Transcriptome and protein expression analysis implicated perturbation of TGF-beta signaling in the pathogenesis of aneurysm in fibulin-4 deficient mice. Our results show that the dosage of a single gene can determine the severity of aneurysm formation and imply that disturbed TGF-beta signaling underlies multiple aneurysm phenotypes.

Topics: Animals; Aorta, Thoracic; Aortic Aneurysm; Aortic Valve; Extracellular Matrix Proteins; Heart Valve Diseases; Homeostasis; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Mice, Transgenic; Signal Transduction; Transcription, Genetic; Transforming Growth Factor beta

Topics: Adrenergic beta-Antagonists; Angiotensin II Type 1 Receptor Blockers; Animals; Aortic Aneurysm; Clinical Trials as Topic; Disease Models, Animal; Emphysema; Fibrillins; Humans; Losartan; Marfan Syndrome; Mice; Microfilament Proteins; Mutation; Transforming Growth Factor beta

Aortic aneurysm and dissection are manifestations of Marfan syndrome (MFS), a disorder caused by mutations in the gene that encodes fibrillin-1. Selected manifestations of MFS reflect excessive signaling by the transforming growth factor-beta (TGF-beta) family of cytokines. We show that aortic aneurysm in a mouse model of MFS is associated with increased TGF-beta signaling and can be prevented by TGF-beta antagonists such as TGF-beta-neutralizing antibody or the angiotensin II type 1 receptor (AT1) blocker, losartan. AT1 antagonism also partially reversed noncardiovascular manifestations of MFS, including impaired alveolar septation. These data suggest that losartan, a drug already in clinical use for hypertension, merits investigation as a therapeutic strategy for patients with MFS and has the potential to prevent the major life-threatening manifestation of this disorder.

Topics: Adrenergic beta-Antagonists; Angiotensin II Type 1 Receptor Blockers; Animals; Antibodies; Aorta; Aortic Aneurysm; Disease Models, Animal; Elastic Tissue; Female; Fibrillin-1; Fibrillins; Losartan; Lung; Lung Diseases; Marfan Syndrome; Mice; Microfilament Proteins; Mutation; Neutralization Tests; Pregnancy; Pregnancy Complications; Propranolol; Pulmonary Alveoli; Receptor, Angiotensin, Type 1; Signal Transduction; Transforming Growth Factor beta

Marfan syndrome (MFS), a condition caused by fibrillin-1 gene mutation is associated with aortic aneurysm that shows elastic lamellae disruption, accumulation of glycosaminoglycans, and vascular smooth muscle cell (VSMC) apoptosis with minimal inflammatory response. We examined aneurysm tissue and cultured cells for expression of transforming growth factor-beta1 to -beta3 (TGFbeta1 to 3), hyaluronan content, apoptosis, markers of cell migration, and infiltration of vascular progenitor cells (CD34).. MFS aortic aneurysm (6 males, 5 females; age 8 to 78 years) and normal aorta (5 males, 3 females; age 22 to 56 years) were used. Immunohistochemistry showed increased expression of TGFbeta1 to 3, hyaluronan, and CD34-positive microcapillaries in MFS aneurysm compared with control. There was increased expression of TGFbeta1 to 3 and hyaluronan in MFS cultured VSMCs, adventitial fibroblasts (AF), and skin fibroblasts (SF). Apoptosis was increased in MFS (VSMC: mean cell loss in MFS 29%, n of subjects=5, versus control 8%, n=3, P<0.05; AF: 28%, n=5 versus 7%, n=5, P<0.05; SF: 29%, n=3 versus 4%, n=3, not significant). In MFS, there was a 2-fold increase in adventitial microcapillaries containing CD34-positive cells compared with control tissue. Scratch wound assay showed absence of CD44, MT1-MMP, and beta-3 integrin at the leading edge of migration in MFS indicating altered directional migration. Western blot showed increased expression of TGFbeta1 to 3 in MFS but no change in expression of CD44, MT1-MMP, or beta-3 integrin compared with controls.. There was overexpression of TGF-beta in MFS associated with altered hyaluronan synthesis, increased apoptosis, impaired progenitor cell recruitment, and abnormal directional migration. These factors limit tissue repair and are likely to contribute to aneurysm development.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Aorta; Aortic Aneurysm; Aortic Dissection; Apoptosis; Blood Vessel Prosthesis Implantation; Cells, Cultured; Child; Elective Surgical Procedures; Female; Fibroblasts; Gene Expression Regulation; Humans; Hyaluronan Receptors; Hyaluronic Acid; Integrin beta3; Male; Marfan Syndrome; Matrix Metalloproteinases; Matrix Metalloproteinases, Membrane-Associated; Middle Aged; Muscle Cells; Muscle, Smooth, Vascular; Transforming Growth Factor beta; Transforming Growth Factor beta1; Transforming Growth Factor beta2; Transforming Growth Factor beta3

Topics: Aged; Aged, 80 and over; Aortic Aneurysm; Aortic Dissection; Biomarkers, Tumor; Carcinoma, Hepatocellular; Fibrillin-1; Fibrillins; Humans; Liver Neoplasms; Male; Microfilament Proteins; Tomography, X-Ray Computed; Transforming Growth Factor beta

Topics: Animals; Aortic Aneurysm; Disease Models, Animal; Humans; Mice; Muscle, Smooth, Vascular; Reproducibility of Results; Transforming Growth Factor beta; Transplantation, Heterologous; United States