Abstract 10435: Blood Flow Patterns Regulate Efferocytosis in Endothelia Cells

Abstract

Introduction: Flowing blood generates a frictional force called shear stress that plays an important role in endothelial dysfunction and atherosclerosis. The disturbed flow (d-flow) pattern causes the preferential localization of atherosclerotic lesions, while regions with steady laminar flow (s-flow) are protected against atherosclerosis. Efferocytosis is a process by which apoptotic tissue is recognized for engulfment by phagocytic cells. Defective efferocytosis promotes advanced atherosclerosis. Hypothesis: We hypothesized that blood flow patterns regulate EC efferocytosis and subsequent endothelial dysfunction and contribute to the development of atherosclerosis. Methods: Primary human aortic ECs (HAECs) were exposed to s-flow and d-flow in a step-flow channel, and the changes of efferocytosis receptors in ECs and endothelial dysfunction were investigated. To investigate whether defective efferocytosis plays a role in endothelial dysfunction, HAECs were transfected with a control plasmid or MerTK CRISPR/Cas9 knockout plasmid. Results and Conclusions: Our results showed that efferocytosis regulators, such as Gas6, Pros1, and MerTK, were upregulated under s-flow conditions while inhibited under d-flow conditions compared to static conditions. Our data also showed that MerTK knockout decreased expression of VE-cadherin and CD31, while increased expression of Snail, Slug, and Twist1 as well as α-SMA, N-cadherin, calponin, and FSP1. Of note, VE-cadherin is a strictly endothelial-specific adhesion molecule located at junctions between ECs. As expected, our data showed that MerTK knockout markedly inhibited VE-cadherin expression, indicating that defective efferocytosis increases endothelial barrier dysfunction. This indicates that MerTK-mediated defective efferocytosis in ECs may play an important role in arterial areas exposed to d-flow where prone to atherosclerosis.