Abstract 13243: Integrin Linked Kinase Expression in Human Valvular Endothelial Cells Plays a Protective Role in Calcific Aortic Valve Disease

Abstract

Introduction: Calcific aortic valve disease (CAVD) is the most common valvular heart disease in the aging population. CAVD is a highly active ossification process originated in valvular interstitial cells which differentiate towards an osteoblastic phenotype. However, the role of valvular endothelial cells in CAVD has not been fully explored. We previously demonstrated that ILK expression in vascular endothelium plays an essential cardioprotective role. Hypothesis: Endothelial ILK plays a protective role in human valvular endothelial cells osteogenesis. Methods and Results: Human aortic valves were obtained from 52 patients with calcific aortic stenosis compared with 16 non-calcified aortic valves and ILK levels were analyzed. Our study showed a significant relationship between the degree of AV calcification and decreased ILK expression detected by IHQ and qPCR (p< 0,013). Moreover, decreased ILK expression correlated with BMP2 and Runx2, two markers of valvular calcification (p<0.01). Human valvular endothelial cells (hVECs) isolated from non-calcified controls display the ability to calcify when cultured in pro-calcifiying conditions and ILK levels were unaffected by the pro-calcifiying conditions. However, silencing ILK expression in hVECs resulted in decreased NO production, increased expression of calcific disease markers Runx2, BMP2, and osteopontin. ILK silencing in hVECs induced calcium deposition, determined by alizarin red staining, when cultured in pro-calcifiying conditions. Thus, our results suggest that decreased ILK expression could promote endothelial to osteogenic phenotype transition. Restoring nitric oxide levels by DETA-NONOate treatment in ILK silenced hVEC was able to reverse those effects partially. Conclusions: Collectively, our results point to a crucial role of ILK in maintaining human valve endothelial cell function preventing valvular calcification.