Abstract 445: Endothelial Inflammation and Loss of Bone Morphogenetic Protein Receptor 2 in Oscillatory Shear Stress Model

Abstract

Background: Bone Morphogenetic Protein Receptor II (BMPR2) plays an unexpected role as a critical anti-inflammatory and anti-atherogenic protein in endothelial cells (ECs) via a reactive oxygen species (ROS) and NFκB-dependent mechanism. Pro-atherogenic stimuli such as disturbed laminar flow, angiotensin II, hypercholesterolemia and the pro-inflammatory cytokine TNFα, significantly downregulate BMPR2 expression in endothelium, while anti-atherogenic stimuli such as laminar flow and statins upregulate BMPR2’s expression in vivo and in vitro. These findings suggest that there may be a common mechanism by which pro-atherogenic factors downregulate BMPR2 expression and that protecting or restoring its expression could be a novel therapeutic approach for prevention and treatment of atherosclerosis. Our preliminary studies have identified microRNAs that possibly play a causative role in the loss of BMPR2, by binding to its 3’-UTR, leading to degradation of BMPR2, endothelial dysfunction, inflammation, and subsequent atherosclerosis. Hypothesis: Rescuing loss of BMPR2 will decrease endothelial inflammation and atherosclerosis Methods: Our in vitro model of disturbed blood flow is characterized by a cone and plate system, wherein mouse aortic endothelial cells are subjected to unidirectional laminar shear (LS 15 dyn/cm2) or oscillatory shear (OS, +/1 5 dyn/cm2 at 1 Hz frequency) for 24 hours. Endothelial cell inflammatory markers, BMPR2, and specific microRNA mRNA transcript fold changes, were then assessed via qPCR. Results: Under oscillatory flow conditions, in our in vitro shear stress system, BMPR2 is lost and mouse aortic endothelial cells acquire an inflammation phenotype, with a corresponding increase in the fold change of mRNA for microRNAs-17, 21, 25, and 181. Conclusion: We have identified microRNAs that may target BMPR2, leading to its degradation, and subsequent onset of endothelial inflammation. Blocking the aforementioned microRNAs may represent a novel therapy in the treatment of endothelial inflammation and subsequent atherosclerosis.