Abstract P1069: Integrin Linked Kinase Controls Human Valve Endotelial Cells Pro-osteogenic Activation In A TFG-b/NO Dependent Manner

Abstract

Calcific aortic valve disease (CAVD) is expected in the aging population. CAVD physiopathology arises from endothelial dysfunction leading to lipid accumulation, inflammation, and osteogenic transformation. Many studies suggest that valve endothelial cells (VECs) undergoing EndMT may differentiate into osteoblastic interstitial cells. We previously showed that Integrin linked kinase (ILK) regulates vasomotor function by preventing endothelial nitric oxide synthase uncoupling. ILK expression in vascular endothelium plays an essential cardioprotective role. Moreover, we have found a significant negative correlation between human valve protein levels of ILK and the osteogenic marker Runx2 and BMP2 in 70 patients with calcific aortic stenosis, a higher decrease at the endothelial level. We hypothesized that Endothelial ILK plays a protective role in human valve endothelial cells osteogenic transition. Isolation of human valve endothelial cells from the aortic (aortic hVECs) and ventricular sides (ventricular hVECs) show a specific ILK decrease in the aortic hVECs from calcific compared to non-calcified valve (p<0.05). Silencing ILK expression in hVECs decreased NO production and increased ROS (Reactive Oxygen Species) production as early as 72 hours. After five days of silencing ILK, hVEC express myofibroblast markers SM22a, α-SMA, MMP12, MMP9, and SNAI 1 while losing the endothelial markers (CD31, and vWF (p<0.01). ILK silenced hVECs (siILK-hVECs) express the osteogenic marker RunX2 indicating osteogenic differentiation and developed calcified nodules. Cell treatment with Noggin, a BMP2 antagonist, did not reverse the increase of Runx2, thus excluding the implication of the BMP2/RUNX2 axis. However, silk-hVECs showed an increase in phosphorylated-SMAD 2, suggesting a TFG-β -dependent mechanism. Treatment of siILK-hVECs with the NO donor DETA-NO decreased Smad 2 activation and RunX2. Moreover, DETA-NO treated siILK hVECs cultured in pro-osteogenic media did not develop calcification. Collectively, our results point to a crucial role of ILK in keeping human valve endothelial cell phenotype preventing valve calcification in a Nitric Oxide-TFGβ1 dependent manner. Financed by the Regional European fund “a way to achieve Europe.” JCCM SBPLY/19/180501/000055S and ISCIII PI20/00930