Project description:Introduction: Renal failure is associated with aortic valve calcification. Using our rat model of uraemia-induced reversible aortic valve calcification, we assessed the role of apoptosis and survival pathways in aortic valve calcification. We also explored the effects of raloxifene - an estrogen receptor modulator on valvular calcification. Methods: Gene array analysis was performed in aortic valves obtained from 3 groups of rats (n=7 each): calcified valves from rats fed with uremic diet -high-adenine (0.75%), high-phosphate diet (1.5%), valves after calcification resolution following diet cessation (reversibility) and control. In addition, four groups of rats (n=10 each) were used in order to evaluate the effect of raloxifene in aortic valve calcification: three groups as mentioned above and a fourth group fed with the uremic diet which also received daily raloxifene. Evaluation of these groups included imaging, histology and antigen expression analysis. Results: Gene array results showed that the majority of the expressed genes that were altered were from the diet group valves. Most apoptosis-related genes were changed in a pro-apoptotic direction in calcified valves. Apoptosis and decrease in several survival pathways were confirmed in calcified valves. Resolution of aortic valve calcification was accompanied by decreased apoptosis and upregulation of these ant-apoptotic pathways. Imaging and histology demonstrated that raloxifene significantly decreased aortic valve calcification. Conclusion: Downregulation of several survival pathways and apoptosis are involved in the pathogenesis of aortic valve calcification. The beneficial effect of raloxifene in valve calcification is related to apoptosis modulation. This novel observation is important for developing remedies for aortic valve calcification in patients with renal failure. Introduction: Renal failure is associated with aortic valve calcification. Using our rat model of uraemia-induced reversible aortic valve calcification, we assessed the role of apoptosis and survival pathways in aortic valve calcification. We also explored the effects of raloxifene - an estrogen receptor modulator on valvular calcification. Methods: Gene array analysis was performed in aortic valves obtained from 3 groups of rats (n=7 each): calcified valves from rats fed with uremic diet -high-adenine (0.75%), high-phosphate diet (1.5%), valves after calcification resolution following diet cessation (reversibility) and control. In addition, four groups of rats (n=10 each) were used in order to evaluate the effect of raloxifene in aortic valve calcification: three groups as mentioned above and a fourth group fed with the uremic diet which also received daily raloxifene. Evaluation of these groups included imaging, histology and antigen expression analysis. Results: Gene array results showed that the majority of the expressed genes that were altered were from the diet group valves. Most apoptosis-related genes were changed in a pro-apoptotic direction in calcified valves. Apoptosis and decrease in several survival pathways were confirmed in calcified valves. Resolution of aortic valve calcification was accompanied by decreased apoptosis and upregulation of these ant-apoptotic pathways. Imaging and histology demonstrated that raloxifene significantly decreased aortic valve calcification. Conclusion: Downregulation of several survival pathways and apoptosis are involved in the pathogenesis of aortic valve calcification. The beneficial effect of raloxifene in valve calcification is related to apoptosis modulation. This novel observation is important for developing remedies for aortic valve calcification in patients with renal failure.
Project description:Aortic remodeling is a cause and consequence of hypertension. It increases workload on the heart and enhances arterial pulsatility in the microcirculation. We have shown that excessive endothelial stretch leads to release of Growth Arrest Specific 6 (GAS6), which in turn activates the tyrosine kinase receptor Axl on monocytes, and causes immune activation and inflammation. We hypothesized that GAS6/Axl blockade would reduce renal and vascular inflammation and lessen renal dysfunction in the setting of chronic aortic remodeling. We characterized a model aortic remodeling in mice following a 2-week infusion of angiotensin II (ang II). Aortas demonstrated increased mural collagen and mechanical testing revealed a marked loss of Windkessel function or energy storage that persisted for 6 months following ang II. Renal function studies showed a reduced ability to excrete a volume load, a progressive increase in albuminuria and tubular damage as estimated by Periodic Acid Schiff (PAS) staining. Treatment with the Axl inhibitor R428 beginning 2 months after ang II infusion had minimal effect on aortic remodeling 2 months later, but reduced the infiltration of T cells, g/d T cells and macrophages into the aorta and kidney, and improved renal excretory capacity, reduced albuminuria, and reduced evidence of renal tubular damage. We conclude that brief episodes of hypertension can induce chronic aortic remodeling which in turn associates with a low-grade inflammation of the aorta and kidneys and evidence of renal dysfunction. These events are mediated at least in part by GAS6/Axl signaling and are improved with Axl blockade.
Project description:Located at the junction of left ventricle and ascending aorta, aortic root is a central cardiovascular structure consisting of aortic valve and coronary ostium that are essential for systemic and coronary circulation, respectively. Malformations of aortic valve and coronary ostium are common birth defects and may occur together in human patients, leading to complex complications including aortic valve stenosis, myocardial ischemia, heart failure and sudden cardiac death. Despite of their physiological and clinical significances, the developmental and molecular mechanisms by which coordinate the formation of aortic valve and coronary ostium remain poorly understood. Here we report that SOX17 (SRY-box 17) is an essential transcription factor required for the maturation of aortic root, as well as the patterning of aortic valve and coronary ostium. We show in mouse that deletion of Sox17 in the aortic root endothelium results in defective aortic valve with underdeveloped non-coronary leaflet (NCL) or bicuspid aortic valve (BAV) without NCL. The valve defects are accompanied by misplaced left coronary ostium that reduces coronary blood flow, leading to myocardial hypoxia and death of embryos. Mechanistically, deletion of Sox17 decreases the expression of Pdgfb (Platelet derived growth factor, B polypeptide) in the aortic root endothelium and the PDGF growth signaling in the NCL mesenchyme and aortic root smooth muscle, both of which are derived from the second heart field (SHF) cardiomyocyte precursors. Furthermore, the deletion upregulates the expression of Ctgf (Connective tissue growth factor) and the extracellular matrix (ECM) genes, whereas downregulates the vascular smooth muscle genes, in the forming aortic root. Together, these findings support a developmental disease mechanism in which delayed growth and maturation of aortic root, due to lack of SOX17-PDGF/CTGF signaling, contributes to BAV and CAAs, two common congenital cardiovascular defects.
Project description:Few studies have assessed the patterns of parasite populations of rodents over a longitudinal gradient in Chile. In this work, the gastrointestinal helminthic fauna of invasive rodents in Chile was examined to assess the association between their presence/absence and abundance with latitude, host sex, and host body condition, and to assess the coexistence and correlation of the abundance between parasite species. Rodents were obtained from 20 localities between 33 and 43°S. Helminths were extracted from the gastrointestinal tract and identified morphologically. Overall, 13 helminth taxa were obtained. The most frequently identified parasite species was Heterakis spumosa, and the most abundant was Syphacia muris, while Physaloptera sp. was the most widely distributed. No locality presented with a coexistence that was different from that expected by chance, while the abundance of five helminthic species correlated with the abundance of another in at least one locality, most likely due to co-infection rather than interaction. Host sex was associated with parasite presence or abundance, and female sex-biased parasitism was notably observed in all cases. Body condition and latitude presented either a positive or negative association with the presence or abundance of parasites depending on the species. It is notable that the likely native Physaloptera sp. is widely distributed among invasive rodents. Further, gravid females were found, suggesting spillback of this species to the native fauna. The low frequency and abundance of highly zoonotic hymenolepid species suggest that rodents are of low concern regarding gastrointestinal zoonotic helminths.