Abstract 4366535: Targeting Endothelial CD47 to Mitigate Atherosclerosis by Restoring PPARγ-Dependent Cholesterol Efflux and Efferocytosis

Abstract

Introduction: CD47, an anti-phagocytic protein, is upregulated in human and murine atherosclerotic plaques. While systemic CD47 blockade reduces atherosclerosis by enhancing efferocytosis, it causes transient anemia due to red blood cell clearance, limiting clinical use. The role of endothelial CD47 in atherogenesis is unclear. We explore how endothelial CD47 promotes atherosclerosis by inhibiting efferocytosis and cholesterol metabolism. Hypothesis: We hypothesize that endothelial CD47 promotes atherosclerosis, in part, by impairing PPARγ-mediated cholesterol efflux and efferocytosis, leading to defective autophagy and exacerbating vascular inflammation. Methods: We utilized scRNA-seq alongside molecular, cellular, and biochemical assays to investigate the role of endothelial CD47 in regulating efferocytosis, autophagy, and inflammation. We have generated endothelial-specific CD47 knockout (EC-CD47iKO) atherosclerotic models on ApoE-/- background and PCSK9-AAV8-injected mice fed a Western diet. To assess therapeutic potential, mice with established atherosclerosis were treated with lipid nanoparticle–encapsulated siRNAs targeting endothelial CD47 (CD47 siLNP). Results: Endothelial-specific deletion of CD47 significantly reduced atherosclerotic plaque burden and necrotic core formation in both ApoE-/- and PCSK9-AAV8 mouse models. CD47-deficient endothelial cells showed decreased expression of pro-inflammatory genes and increased expression of efferocytic receptors (LRP1, MERTK, SIRPα). Macrophages from EC-CD47iKO mice also exhibited elevated expression of efferocytosis-related genes. Co-culture experiments with apoptotic Jurkat cells revealed enhanced PPARγ-dependent ABCG1-mediated cholesterol efflux in CD47-deficient ECs. Transcriptomic analysis of aortic ECs indicated inhibition of inflammatory markers, also enrichment of autophagy and lipid metabolism pathways. CD47 deletion improved vascular function, evidenced by increased eNOS phosphorylation, reduced ROS production, and elevated autophagic flux (increased LC3-II, decreased p62). Finally, the treatment of endothelial targeting CD47 silencing siLNPs significantly attenuated atherosclerosis progression in mice with established disease Conclusion: Endothelial CD47 promotes atherogenesis by impairing PPARγ-mediated efferocytosis and cholesterol efflux, thereby enhancing vascular inflammation. Targeting endothelial CD47 represents a promising cell-specific therapeutic strategy for advanced atherosclerosis