transforming-growth-factor-beta and Atrial-Remodeling

A century after the discovery of Chagas disease, studies are still needed to establish the complex pathophysiology of this disease. However, it is known that several proteins and molecules are related to the establishment of this disease, its evolution, and the appearance of its different clinical forms. Metalloproteinases and their tissue inhibitors, galectins, and TGF-

Topics: Atrial Remodeling; Chagas Cardiomyopathy; Disease Progression; Galectins; Gene Expression Regulation; Humans; Matrix Metalloproteinases; Signal Transduction; Tissue Inhibitor of Metalloproteinases; Transforming Growth Factor beta; Trypanosoma cruzi; Ventricular Remodeling

Chagas disease is caused by the trypanosomatid Trypanosoma cruzi, which chronically causes heart problems in up to 30% of infected patients. Chagas disease was initially restricted to Latin America. However, due to migratory events, this disease may become a serious worldwide health problem. During Chagas disease, many patients die of cardiac arrhythmia despite the apparent benefits of anti-arrhythmic therapy (e.g., amiodarone). Here, we assimilate the cardiac form of Chagas disease to an inflammatory cardiac disease. Evidence from the literature, mostly provided using experimental models, supports this view and argues in favor of new strategies for treating cardiac arrhythmias in Chagas disease by modulating cytokine production and/or action. But the complex nature of myocardial inflammation underlies the need to better understand the molecular mechanisms of the inflammatory response during Chagas disease. Here, particular attention has been paid to tumor necrosis factor alpha (TNF) and transforming growth factor beta (TGF-β) although other cytokines may be involved in the chagasic cardiomyopathy.

Topics: Action Potentials; Animals; Anti-Inflammatory Agents; Atrial Remodeling; Chagas Cardiomyopathy; Heart Conduction System; Heart Rate; Host-Pathogen Interactions; Humans; Inflammation Mediators; Myocardial Contraction; Myocarditis; Myocytes, Cardiac; Signal Transduction; Transforming Growth Factor beta; Trypanosoma cruzi; Tumor Necrosis Factor-alpha; Ventricular Remodeling

Atrial fibrillation is the most common sustained arrhythmia, but its mechanisms are poorly understood. In particular, little is known about the factors that contribute to the establishment of persistent or permanent atrial fibrillation. This review addresses possible common signaling pathways that might promote both structural and electrical remodeling of the atria, thus contributing to atrial fibrillation perpetuation.. Sustained atrial fibrillation may trigger an inflammatory response leading to activation of myofibroblasts and to the release of cytokines such as transforming growth factor-β and platelet-derived growth factor, as well as profibrotic proteins such as galectin-3. Activation of signaling cascades involving such proteins is critical for the development of fibrosis and may also lead to ion channel dysfunction, which, along with myocyte apoptosis and extracellular matrix generation and turnover, likely contributes to both electrical and structural remodeling and predisposes to atrial fibrillation.. Identifying upstream strategies targeting molecular pathways that are common to fibrosis and electrical remodeling leading to atrial fibrillation perpetuation is highly desirable. This would facilitate finding new target genes with pleiotropic effects on the expression of ion channel proteins in myocytes and profibrotic molecules in nonmyocyte cells that are important for pathologic remodeling, which could become an important goal in persistent atrial fibrillation therapy.

Topics: Apoptosis; Atrial Fibrillation; Atrial Remodeling; Extracellular Matrix; Fibrosis; Galectin 3; Heart Atria; Heart Conduction System; Humans; Inflammation; Myocytes, Cardiac; Myofibroblasts; Platelet-Derived Growth Factor; Signal Transduction; Transforming Growth Factor beta

Topics: Angiotensin II; Atrial Remodeling; Humans; Phosphatidylinositol 3-Kinases; Signal Transduction; Somatomedins; Transforming Growth Factor beta; Ventricular Remodeling

BACKGROUND The structural remodeling of atrial architecture, especially increased amounts of fibrosis, is a critical substrate to atrial fibrillation (AF). Doxycycline (Doxy) has recently been shown to exert protective effects against fibrogenic response. This study investigated whether doxycycline (Doxy) can sufficiently ameliorate the fibrosis-induced changes of atrial conduction and AF vulnerability in a chronic intermittent hypoxia (CIH) rat model. MATERIAL AND METHODS Sixty rats were randomized into 3 groups: Control, CIH, and CIH with Doxy treatment (DOXY) group. CIH rats were exposed to CIH (6 h/d) and Doxy-treated rats were treated with Doxy during processing CIH. After 6 weeks, echocardiographic and hemodynamic parameters were measured. Isolated atrial epicardial activation mapping and heart electrophysiology were performed. The extent of atrial interstitial fibrosis were estimated by Masson's trichrome staining. The expression levels of TGF-ß1 and downstream factors were determined by real-Time PCR, immunohistochemistry, and Western blot analysis. RESULTS Compared to Control rats, the CIH rats showed significant atrial interstitial fibrosis, longer inter-atrial conduction time, and elevated conduction inhomogeneity and AF inducibility, and the expression of TGF-ß1, TGF-ßRI, TGF-ßRII, P-Smad2/3, alpha-SMA, CTGF, and Collagen I were significantly increased, whereas the velocity of atrial conduction and the expression of miR-30c were dramatically decreased. All of these changes were significantly improved by Doxy treatment. CONCLUSIONS The findings suggested that Doxy can profoundly mitigate atrial fibrosis, conduction inhomogeneity as well as high AF inducibility secondary to fibrosis in a CIH rat model through suppressing the TGF-ß1 signaling pathway.

Topics: Animals; Atrial Fibrillation; Atrial Remodeling; China; Disease Models, Animal; Doxycycline; Fibrosis; Heart Atria; Heart Rate; Hypoxia; Male; Rats; Rats, Sprague-Dawley; Signal Transduction; Transforming Growth Factor beta

Arterial stiffness and wall shear stress are powerful determinants of cardiovascular health, and arterial stiffness is associated with increased cardiovascular mortality. Low and oscillatory wall shear stress, termed disturbed flow (d-flow), promotes atherosclerotic arterial remodeling, but the relationship between d-flow and arterial stiffness is not well understood. The objective of this study was to define the role of d-flow on arterial stiffening and discover the relevant signaling pathways by which d-flow stiffens arteries.. D-flow was induced in the carotid arteries of young and old mice of both sexes. Arterial stiffness was quantified ex vivo with cylindrical biaxial mechanical testing and in vivo from duplex ultrasound and compared with unmanipulated carotid arteries from 80-week-old mice. Gene expression and pathway analysis was performed on endothelial cell-enriched RNA and validated by immunohistochemistry. In vitro testing of signaling pathways was performed under oscillatory and laminar wall shear stress conditions. Human arteries from regions of d-flow and stable flow were tested ex vivo to validate critical results from the animal model.. D-flow induced arterial stiffening through collagen deposition after partial carotid ligation, and the degree of stiffening was similar to that of unmanipulated carotid arteries from 80-week-old mice. Intimal gene pathway analyses identified transforming growth factor-β pathways as having a prominent role in this stiffened arterial response, but this was attributable to thrombospondin-1 (TSP-1) stimulation of profibrotic genes and not changes to transforming growth factor-β. In vitro and in vivo testing under d-flow conditions identified a possible role for TSP-1 activation of transforming growth factor-β in the upregulation of these genes. TSP-1 knockout animals had significantly less arterial stiffening in response to d-flow than wild-type carotid arteries. Human arteries exposed to d-flow had similar increases TSP-1 and collagen gene expression as seen in our model.. TSP-1 has a critical role in shear-mediated arterial stiffening that is mediated in part through TSP-1's activation of the profibrotic signaling pathways of transforming growth factor-β. Molecular targets in this pathway may lead to novel therapies to limit arterial stiffening and the progression of disease in arteries exposed to d-flow.

Topics: Aging; Animals; Atrial Remodeling; Carotid Arteries; Cell Line; Collagen; Disease Models, Animal; Down-Regulation; Endothelium, Vascular; Female; Humans; Immunohistochemistry; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Protein Serine-Threonine Kinases; Receptor, Transforming Growth Factor-beta Type I; Receptors, Transforming Growth Factor beta; RNA, Ribosomal, 18S; Shear Strength; Thrombospondin 1; Transforming Growth Factor beta; Vascular Stiffness

Diabetes mellitus (DM) is an independent risk factor for atrial fibrillation (AF). However, the underlying mechanisms for the increased propensity for AF in the setting of DM and the potential effects of probucol on atrial remodeling remain unclear.. Eighty Japanese rabbits were randomly assigned to normal/control group (Control, n = 20), alloxan-induced diabetic group (DM, n = 20), probucol-treated group (Control-P, n = 20), and probucol-treated diabetic group (DM-P, n = 20). Rabbits in the DPR and CPR groups were orally administered probucol (1,000 mg/day) for 8 weeks. Serum and left atrial tissue malonaldehyde (MDA), superoxide dismutase (SOD), myeloperoxidase (MPO), and catalase (CAT) levels were assessed. Isolated Langendorff perfused rabbit hearts were prepared to evaluate atrial refractory effective period (AERP) and its dispersion (AERPD), interatrial conduction time (IACT), and vulnerability to AF. Atrial interstitial fibrosis was also evaluated. The mRNA expression levels of TNF-α and TLR4 were analyzed. The protein expressions of NF-κB, HSP70, TGF-β, and ERK in left atrial tissue were analyzed by Western blot. Probucol administration decreased the inducibility of AF in diabetic rabbits and attenuated atrial interstitial fibrosis. The DM-P rabbits exhibited significant alleviation of oxidative stress, evidenced by reduced serum and tissue MDA, compared with diabetic rabbits. Moreover, NF-κB, TGF-β, and HSP70 protein expression and TNF-α mRNA expression were significantly downregulated by probucol treatment in alloxan-induced diabetic rabbits.. Probucol prevents atrial remodeling and suppresses AF development in alloxan-induced diabetic rabbits. Its inhibitory effects on oxidative stress, NF-κB, TGF-β, and TNF-α overexpression may contribute to its antiremodeling effects.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Atrial Fibrillation; Atrial Remodeling; Biomarkers; Diabetes Mellitus, Experimental; Fibrosis; Gene Expression Regulation; Heart Atria; Inflammation Mediators; NF-kappa B; Oxidative Stress; Probucol; Rabbits; RNA, Messenger; Signal Transduction; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Atrial Fibrillation; Atrial Remodeling; Diabetes Mellitus, Experimental; Heart Atria; Inflammation Mediators; NF-kappa B; Oxidative Stress; Probucol; Signal Transduction; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha

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

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