transforming-growth-factor-beta and Aneurysm

Low-density lipoprotein receptor-related protein-1 (LRP1) is a large endocytic and signaling receptor that is widely expressed. In the liver, LRP1 plays an important role in regulating the plasma levels of blood coagulation factor VIII (fVIII) by mediating its uptake and subsequent degradation. fVIII is a key plasma protein that is deficient in hemophilia A and circulates in complex with von Willebrand factor. Because von Willebrand factor blocks binding of fVIII to LRP1, questions remain on the molecular mechanisms by which LRP1 removes fVIII from the circulation. LRP1 also regulates cell surface levels of tissue factor, a component of the extrinsic blood coagulation pathway. This occurs when tissue factor pathway inhibitor bridges the fVII/tissue factor complex to LRP1, resulting in rapid LRP1-mediated internalization and downregulation of coagulant activity. In the vasculature LRP1 also plays protective role from the development of aneurysms. Mice in which the lrp1 gene is selectively deleted in vascular smooth muscle cells develop a phenotype similar to the progression of aneurysm formation in human patient, revealing that these mice are ideal for investigating molecular mechanisms associated with aneurysm formation. Studies suggest that LRP1 protects against elastin fiber fragmentation by reducing excess protease activity in the vessel wall. These proteases include high-temperature requirement factor A1, matrix metalloproteinase 2, matrix metalloproteinase-9, and membrane associated type 1-matrix metalloproteinase. In addition, LRP1 regulates matrix deposition, in part, by modulating levels of connective tissue growth factor. Defining pathways modulated by LRP1 that lead to aneurysm formation and defining its role in thrombosis may allow for more effective intervention in patients.

Topics: Aneurysm; Animals; Atherosclerosis; Blood Coagulation; Elastin; Endocytosis; Extracellular Matrix; Factor VIII; Humans; Lipoproteins, LDL; Liver; Low Density Lipoprotein Receptor-Related Protein-1; Macrophages; Mice; Mice, Knockout; Models, Animal; Models, Molecular; Muscle, Smooth, Vascular; Organ Specificity; Peptide Hydrolases; Platelet-Derived Growth Factor; Protein Conformation; Receptors, LDL; Signal Transduction; Thromboplastin; Transforming Growth Factor beta; Tumor Suppressor Proteins; von Willebrand Factor

When aortic cells are under stress, such as increased hemodynamic pressure, they adapt to the environment by modifying their functions, allowing the aorta to maintain its strength. To understand the regulation of this adaptive response, we examined transcriptomic and epigenomic programs in aortic smooth muscle cells (SMCs) during the adaptive response to AngII (angiotensin II) infusion and determined its importance in protecting against aortic aneurysm and dissection (AAD).. We performed single-cell RNA sequencing and single-cell sequencing assay for transposase-accessible chromatin (scATAC-seq) analyses in a mouse model of sporadic AAD induced by AngII infusion. We also examined the direct effects of YAP (yes-associated protein) on the SMC adaptive response in vitro. The role of YAP in AAD development was further evaluated in AngII-infused mice with SMC-specific. In wild-type mice, AngII infusion increased medial thickness in the thoracic aorta. Single-cell RNA sequencing analysis revealed an adaptive response in thoracic SMCs characterized by upregulated genes with roles in wound healing, elastin and collagen production, proliferation, migration, cytoskeleton organization, cell-matrix focal adhesion, and PI3K-PKB/Akt (phosphoinositide-3-kinase-protein kinase B/Akt) and TGF-β (transforming growth factor beta) signaling. ScATAC-seq analysis showed increased chromatin accessibility at regulatory regions of adaptive genes and revealed the mechanical sensor YAP/transcriptional enhanced associate domains as a top candidate transcription complex driving the expression of these genes (eg,. Aortic stress triggers the systemic epigenetic induction of an adaptive response (eg, wound healing, proliferation, matrix organization) in thoracic aortic SMCs that depends on functional biomechanical signal transduction (eg, YAP signaling). Our study highlights the importance of the adaptive response in maintaining aortic homeostasis and preventing AAD in mice.

Topics: Aneurysm; Animals; Aorta; Aorta, Thoracic; Aortic Aneurysm, Thoracic; Aortic Dissection; Cells, Cultured; Chromatin; Collagen; Humans; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocytes, Smooth Muscle; Proto-Oncogene Proteins c-akt; Transforming Growth Factor beta

Abdominal aortic aneurysm (AAA) is a frequent, potentially life-threatening, disease that can only be treated by surgical means such as open surgery or endovascular repair. No alternative treatment is currently available, and despite expanding knowledge about the pathomechanism, clinical trials on medical aneurysm abrogation have led to inconclusive results. The heterogeneity of human AAA based on histologic examination is thereby generally neglected. In this study we aimed to further elucidate the role of these differences in aneurysm disease.. Tissue samples from AAA and popliteal artery aneurysm patients were examined by histomorphologic analysis, immunohistochemistry, Western blot, and polymerase chain reaction. The results were correlated with clinical data such as aneurysm diameter and laboratory results.. The morphology of human AAA vessel wall probes varies tremendously based on the grade of inflammation. This correlates with increasing intima/media thickness and upregulation of the vascular endothelial growth factor cascade but not with any clinical parameter or the aneurysm diameter. The phenotypic switch of vascular smooth muscle cells occurred regardless of the inflammatory state and expressional changes of the transcription factors Kruppel-like factor-4 and transforming growth factor-β lead to differential protein localization in aneurysmal compared with control arteries. These changes were in similar manner also observed in samples from popliteal artery aneurysms, which, however, showed a more homogenous phenotype.. Heterogeneity of AAA vessel walls based on inflammatory morphology does not correlate with AAA diameter yet harbors specific implications for basic research and possible aneurysm detection.

Topics: Aneurysm; Angiogenic Proteins; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Aortography; Biomarkers; Cell Dedifferentiation; Computed Tomography Angiography; Dilatation, Pathologic; Extracellular Matrix; Extracellular Matrix Proteins; Humans; Inflammation; Inflammation Mediators; Kruppel-Like Factor 4; Kruppel-Like Transcription Factors; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Phenotype; Popliteal Artery; Transforming Growth Factor beta; Vascular Remodeling

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: Aneurysm; Animals; Extracellular Matrix; Mice; Mice, Knockout; Mutation; Signal Transduction; Smad3 Protein; Transforming Growth Factor beta

Vascular aneurysm is an abnormal local dilatation of an artery that can lead to vessel rupture and sudden death. The only treatment involves surgical or endovascular repair or exclusion. There is currently no approved medical therapy for this condition. Recent data established a strong association between genetic variants in the 9p21 chromosomal region in humans and the presence of cardiovascular diseases, including aneurysms. However, the mechanisms linking this 9p21 DNA variant to cardiovascular risk are still unknown.. Here, we show that deletion of the orthologous 70-kb noncoding interval on mouse chromosome 4 (chr4(Δ70kb/Δ70kb) mice) is associated with reduced aortic expression of cyclin-dependent kinase inhibitor genes p19Arf and p15Inkb. Vascular smooth muscle cells from chr4(Δ70kb/Δ70kb) mice show reduced transforming growth factor-β-dependent canonical Smad2 signaling but increased cyclin-dependent kinase-dependent Smad2 phosphorylation at linker sites, a phenotype previously associated with tumor growth and consistent with the mechanistic link between reduced canonical transforming growth factor-β signaling and susceptibility to vascular diseases. We also show that targeted deletion of the 9p21 risk interval promotes susceptibility to aneurysm development and rupture when mice are subjected to a validated model of aneurysm formation. The vascular disease of chr4(Δ70kb/Δ70kb) mice is prevented by treatment with a cyclin-dependent kinase inhibitor.. The results establish a direct mechanistic link between 9p21 noncoding risk interval and susceptibility to aneurysm and may have important implications for the understanding and treatment of vascular diseases.

Topics: Aneurysm; Animals; Cells, Cultured; Chromosomes; Cyclin-Dependent Kinase Inhibitor p15; Cyclin-Dependent Kinase Inhibitor p19; Disease Models, Animal; Disease Susceptibility; Flavonoids; Gene Expression; Kaplan-Meier Estimate; Matrix Metalloproteinase 12; Mice; Mice, Inbred C57BL; Muscle, Smooth, Vascular; Phenotype; Phosphorylation; Piperidines; Protein Kinase Inhibitors; Risk Factors; Signal Transduction; Smad2 Protein; Transforming Growth Factor beta

Aberrant smooth muscle cell (SMC) plasticity has been implicated in a variety of vascular disorders including atherosclerosis, restenosis, and abdominal aortic aneurysm (AAA) formation. While the pathways governing this process remain unclear, epigenetic regulation by specific microRNAs (miRNAs) has been demonstrated in SMCs. We hypothesized that additional miRNAs might play an important role in determining vascular SMC phenotype. Microarray analysis of miRNAs was performed on human aortic SMCs undergoing phenotypic switching in response to serum withdrawal, and identified 31 significantly regulated entities. We chose the highly conserved candidate miRNA-26a for additional studies. Inhibition of miRNA-26a accelerated SMC differentiation, and also promoted apoptosis, while inhibiting proliferation and migration. Overexpression of miRNA-26a blunted differentiation. As a potential mechanism, we investigated whether miRNA-26a influences TGF-β-pathway signaling. Dual-luciferase reporter assays demonstrated enhanced SMAD signaling with miRNA-26a inhibition, and the opposite effect with miRNA-26a overexpression in transfected human cells. Furthermore, inhibition of miRNA-26a increased gene expression of SMAD-1 and SMAD-4, while overexpression inhibited SMAD-1. MicroRNA-26a was also found to be downregulated in two mouse models of AAA formation (2.5- to 3.8-fold decrease, P < 0.02) in which enhanced switching from contractile to synthetic phenotype occurs. In summary, miRNA-26a promotes vascular SMC proliferation while inhibiting cellular differentiation and apoptosis, and alters TGF-β pathway signaling. MicroRNA-26a represents an important new regulator of SMC biology and a potential therapeutic target in AAA disease.

Topics: Aneurysm; Animals; Apolipoproteins E; Apoptosis; Cell Differentiation; Cell Movement; Cell Proliferation; Culture Media, Serum-Free; Disease Models, Animal; Gene Expression Regulation; Humans; Mice; MicroRNAs; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Signal Transduction; Smad1 Protein; Smad4 Protein; Transforming Growth Factor beta

To address the requirement for TGFbeta signaling in the formation and maintenance of the vascular matrix, we employed lineage-specific mutation of the type II TGFbeta receptor gene (Tgfbr2) in vascular smooth muscle precursors in mice. In both neural crest- and mesoderm-derived smooth muscle, absence of TGFbeta receptor function resulted in a poorly organized vascular elastic matrix in late-stage embryos which was prone to dilation and aneurysm. This defect represents a failure to initiate formation of the elastic matrix, rather than a failure to maintain a preexisting matrix. In mutant tissue, lysyl oxidase expression was substantially reduced, which may contribute to the observed pathology.

Topics: Aneurysm; Animals; Base Sequence; DNA Primers; Elastic Tissue; Female; Gene Expression Regulation, Developmental; Matrix Metalloproteinase 9; Mice; Mice, Mutant Strains; Mice, Transgenic; Muscle, Smooth, Vascular; Mutation; Pregnancy; Protein Serine-Threonine Kinases; Protein-Lysine 6-Oxidase; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta; RNA; Signal Transduction; Tissue Distribution; Transforming Growth Factor beta

Impaired glomerular endothelial integrity is pivotal in various renal diseases and depends on both the degree of glomerular endothelial injury and the effectiveness of glomerular endothelial repair. Glomerular endothelial repair is, in part, mediated by bone marrow-derived endothelial progenitor cells. Peroxisome proliferator activated receptor-gamma (PPAR-gamma) agonists have therapeutic actions independent of their insulin-sensitizing effects, including enhancement of endothelial progenitor cell function and differentiation. We evaluated the effect of PPAR-gamma agonist rosiglitazone (4 mg.kg(-1).day(-1)) on the course of anti-Thy1-glomerulonephritis in rats. Rosiglitazone limited the development of proteinuria and prevented plasma urea elevation (8.1 +/- 0.4 vs. 12.5 +/- 1.1 mmol/l, P = 0.002). Histologically, inflammatory cell influx was not affected, but rosiglitazone-treated rats did show fewer microaneurysmatic glomeruli on day 7 (26 +/- 3 vs. 41 +/- 5%, P = 0.01) and reduced activation of matrix production with reduced renal cortical transforming growth factor-beta, plasminogen activator inhibitor type 1, and fibronectin-1 mRNA expression. However, bone marrow-derived endothelial cell glomerular incorporation was not enhanced (3.1 +/- 0.4 vs. 3.6 +/- 0.3 cells/glomerular cross section; P = 0.31). Rosiglitazone treatment in nonnephritic rats did not influence proteinuria, urea, or renal histology. In conclusion, treatment with PPAR-gamma agonist rosiglitazone ameliorates the course of experimental glomerulonephritis in a nondiabetic model, but not through enhancing incorporation of bone marrow-derived endothelial cells in the glomerulus.

Topics: Aneurysm; Animals; Blood Pressure; Bone Marrow Transplantation; Cell Movement; Disease Models, Animal; Endothelial Cells; Extracellular Matrix; Fibronectins; Gene Expression; Glomerulonephritis, Membranous; Hypoglycemic Agents; Isoantibodies; Kidney Cortex; Kidney Glomerulus; Male; Membrane Proteins; Plasminogen Activator Inhibitor 1; PPAR gamma; Proteinuria; Rats; Rats, Inbred BN; Rosiglitazone; Stem Cells; Thiazolidinediones; Transforming Growth Factor beta; Urea

Endovascular treatment of cerebral aneurysm is safe and effective, but recurrence of disease is frequent compared with results with surgery. The purpose of this study was to determine the effects of recombinant transforming growth factor beta(1) (rTGFbeta(1)) secreted by transplanted autologous vascular smooth muscle cells (VSMC) on results of endovascular treatment.. VSMC from canine femoral arteries were infected with adenovirus vector encoding rTGFbeta(1)/green fluorescent protein (rTGFbeta(1)/GFP) or GFP only. rTGFbeta(1) production was measured with an enzyme-linked immunosorbent assay, and autocrine and paracrine effects of rTGFbeta(1) on cell functions were quantified with a proliferation assay and collagen synthesis. A bilateral carotid aneurysm model was used to compare angiographic and pathologic results after embolization with sponges seeded (n = 14) or not seeded (n = 34) with VSMC expressing TGFbeta(1) or GFP (n = 7 each). Transgene retention was confirmed with Western blot analysis.. In vitro, TGFbeta(1) production varied from 0.9 to 180 ng/mL/d with increasing multiplicity of infection (MOI). Collagen synthesis was doubled at low (<300) MOI and increased by one and a half times at high (>or=300) MOI. rTGFbeta(1) was biologically active, as shown with the mink lung epithelial cell proliferation assay. VSMC grafts showed effective GFP expression up to 3 weeks after transplantation. Angiographic results were improved and neointima thickness was increased with cellular grafts, as compared with controls, but there was no significant difference between aneurysms treated with VSMC encoding rTGFbeta(1)/GFP or GFP vectors.. Cellular grafts can promote healing of aneurysms, but overexpression of rTGFbeta(1)/GFP did not demonstrate added benefits in this model.

Topics: Adenoviridae; Aneurysm; Angiography; Animals; Blotting, Western; Carotid Arteries; Disease Models, Animal; Dogs; Enzyme-Linked Immunosorbent Assay; Gene Expression Regulation; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Immunohistochemistry; Muscle, Smooth, Vascular; Risk Factors; Sensitivity and Specificity; Transforming Growth Factor beta; Transforming Growth Factor beta1

Growth factors (GFs) may favor the healing of aneurysms treated with endovascular techniques by stimulating neointima formation.. Bilateral carotid aneurysms were constructed with venous pouches in 50 pigs and embolized intraoperatively with collagen sponges with and without GFs (platelet-derived growth factor-BB [PDGF-BB] 0.15 or 1.5 microg or transforming growth factor-beta(1) [TGF-beta(1)] 60 or 600 ng) in each animal. DNA synthesis, cell proliferation, and collagen secretion assays were performed to assess the in vitro effects of GFs on neointimal cells harvested from the treated aneurysms. (125)I-PDGF-BB was used to study in vivo GF release from sponges. The thickness of the neointima at the surface of the sponges was measured 2 weeks after surgery. Since porcine aneurysms tend to heal after collagen sponge embolization, this experiment was repeated in dogs, which have shown a propensity for recurrence with the same technique, with 600 ng TGF-beta(1) or platelet extracts.. PDGF-BB stimulated DNA synthesis and cell proliferation, while TGF-beta(1) strongly increased collagen synthesis of neointimal cells in vitro. Clearance of (125)I-PDGF-BB from the sponges followed a biphasic curve, with 1.5% of exogenous PDGF-BB remaining at 1 week. The local delivery of PDGF-BB (0.15 or 1.5 microg) and TGF-beta(1) (600 ng) significantly increased neointimal thickness at the neck of porcine aneurysms, while 60 ng of TGF-beta(1) had no demonstrable effect. TGF-beta(1) (600 ng) or platelet extracts had no influence on canine aneurysms.. PDGF-BB and TGF-beta(1) can stimulate neointimal cells in vitro and neointima formation in vivo, but TGF-beta(1) and platelet extracts do not compensate for deficient thrombosis in canine aneurysms. Effects on the long-term results of embolization remain speculative.

Topics: Aneurysm; Animals; Anticoagulants; Becaplermin; Carotid Arteries; Cell Division; Dogs; Embolization, Therapeutic; Platelet-Derived Growth Factor; Proto-Oncogene Proteins c-sis; Swine; Transforming Growth Factor beta; Tunica Intima