Abstract 338: Novel Role Of Endothelial Cd47 In The Regulation Of Pathogenesis Of Atherosclerosis

Abstract

Background: The anti-phagocytic molecule CD47 is upregulated in atherosclerotic plaques of patients with cerebrovascular disease. However, the role of endothelial cell-specific CD47 in the pathogenesis of atherosclerosis has not yet been defined. Kojima et.al . described atheroprotective effect of anti-CD47 antibody by enhancing efferocytosis in atherosclerosis. In this study, we determined whether endothelialCD47 regulates efferocytosis in atherosclerosis. Methods: Susceptibility to atherosclerosis was evaluated in cross sections of the aortic sinus in atherosclerotic mice. Using single-cell RNA sequencing and efferocytosis assays, we investigated the role of CD47 in regulating efferocytosis in atherosclerotic mouse model. Results: Endothelial cell-specific deletion of CD47 led to significant plaque reduction in aortic sinus of athero-CD47iECKO mice. Cluster analysis and gene expression profiles of 20,000 aortic endothelial cells from atherosclerotic mice identified 10 major cell types: endothelial cells, VSMCs, fibroblasts, B cells, T cells, macrophage, erythrocytes, oligodendrocytes cells, Schwann cells, and pericytes. In athero-CD47iECKO group, subpopulation of endothelial cells as well as fibroblasts, T-cells, B-cells, macrophages, erythrocytes, oligodendrocytes, and pericytes were increased, while vascular smooth muscle cell numbers decreased. Using efferocytosis assay on isolated primary endothelial cells from control and CD47iECKO mice, we observed CD47 deletion induced engulfment of apoptotic Jurkat cells, which had been exposed to NF-κB inhibitor, BAY11-7082 to stimulate apoptotic attributes. Quantitative PCR analyses showed that CD47 deletion increases the expression of efferocytosis receptor FasL, CX3CL1, Gpr132, MerTK, Scarb1, Sirpa, TSP1, and HMGB1. Conclusion: Our study indicates that genetic deletion of CD47 in endothelial cells attenuates atheroma progression by enhancing efferocytosis. This study also reveals phenotypic heterogenicity of endothelial cells at the single-cell level during atherogenesis and provides deeper understanding of endothelial cell biology in atherosclerosis that may facilitate the development of novel therapeutic interventions for cardiovascular disease.