Project description:Multiple molecular and cellular mechanisms are associated with the initiation and progression of aortic valve disease. Alterations in ECM remodeling, increased expression of pro-inflammatory cytokines, calcification, lipid deposition and changes in valve cell phenotype have demonstrated roles in development of aortic valve disease. Mechanical stimulation has a significant role in determining the physiological properties of valve tissue and an altered hemodynamic environment may result in pathological changes. We used microarrays to detail the global of gene expression profiles underlying valve remodeling during valve exposure to of two levels of cyclic mechanical pressure (normotensive 0-80mmHg and hypertensive 0-120mmHg ) on porcine valve tissue transcriptome using Sus Scrofa cDNA microarrays from Affymetrix and we identified distinct classes of up-regulated genes during this process. Hybridizations were carried out with RNA isolated from six independetn samples of valve tissue exposed to normotensive and hypertensive pressure for 24 hours at 1hz frecuency. Differentially expressed genes were identified by The t test with the option of unequal variance was used to calculate P values for each gene. The fold change and Q values for each gene were calculated with SAM program with permutation of 500 . Biological modeling of the differentially expressed genes (DE) was carried out based on GO groups and network analysis in ingenuity Pathway Analysis (IPA). Experiment Overall Design: The experimental design included three biological samples of porcine valve leaflets exposed to cyclic pressures of 0-80 or 0-120 mmHg for 24 hours, representing normotensive and hypertensive diastolic transvalvular pressure, respectively. Using Affymetrix porcine microarrays, we compared global gene expression profiles of aortic valve leaflets exposed to elevated and normal physiological pressure conditions . The effects of cyclic pressure on the transcriptome was determined by comparing the quantity and magnitud of change in gene expression levels of valve leflets, as well evaluating the molecular function each gene has in the cell,in the presence of hypertennsive (experimental) and normotensve pressurec (control).

Project description:Aortic valve stenosis (AVS) is a sexually dimorphic disease, with women often presenting with sustained fibrosis and men with more extensive calcification. However, the intracellular molecular mechanisms that drive these clinically important sex differences remain under explored. Hydrogel scaffolds were designed to recapitulate key aspects of the valve tissue microenvironment and serve as a platform for culture of sex-specific valvular interstitial cells (VICs; precursors to pro-fibrotic myofibroblasts). The hydrogel culture system was used to interrogate intracellular pathways involved in sex-dependent VIC-to-myofibroblast activation and deactivation. RNA-seq was used to define pathways likely to be involved in driving sex-dependent activation. Interventions using small molecule inhibitors were performed to provide mechanistic insight into sex-specific cellular responses to microenvironmental cues, including matrix stiffness and exogenously delivered biochemical factors. In both healthy porcine and human aortic valves, female leaflets had higher baseline activation of the myofibroblast marker, α-smooth muscle actin (α-SMA), compared to male leaflets. When isolated and cultured, female VICs had higher levels of basal α-SMA stress fibers that further increased in response to the hydrogel matrix stiffness, both of which were higher than male VICs. A transcriptomic analysis of male and female porcine VICs revealed Rho-associated protein kinase (RhoA/ROCK) signaling as a potential driver of this sex-dependent myofibroblast activation. Further, we found that genes that escape X-chromosome inactivation, such as BMX and STS (encoding for Bmx non-receptor tyrosine kinase and steroid sulfatase, respectively) partially regulate the elevated female myofibroblast activation via RhoA/ROCK signaling. This finding was confirmed by treating male and female VICs with endothelin-1 and plasminogen activator inhibitor-1, factors that are secreted by endothelial cells and known to drive myofibroblast activation via RhoA/ROCK signaling. Together, in vivo and in vitro results confirm sex-dependencies in myofibroblast activation pathways, and transcriptome analyses and small molecule interventions implicate genes that escape X-chromosome inactivation in regulating sex differences in AVS progression. Our results underscore the importance of considering sex as a biological variable to understand the molecular mechanisms of AVS and help guide sex-based precision therapies.

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Sus scrofa

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