Abstract 4368743: Macrophage Lipid Handling Is Altered in a Mouse Model of a Human Polymorphism that Results in CD73 Loss-of-Function

Abstract

Background: Atherosclerotic cardiovascular disease (ASCVD) remains the leading global cause of death. Purinergic signaling, mediated by ectonucleotidases like CD73, plays a critical role in ASCVD. CD73 converts extracellular AMP to adenosine, dampening inflammation. A rare CD73 SNP (rs200648774, R354C) leads to a loss-of-function (LOF) protein. We generated CD73 LOF (Cys354/Cys354) mice on an Ldlr−/− background, which develop greater atherosclerosis than wild-type (WT, Arg354/Arg354) controls on an atherogenic diet. Objective and Hypothesis: We aimed to uncover mechanisms by which CD73 influences atherosclerosis. Since macrophages are central to plaque development, we hypothesized that CD73 LOF alters macrophage responses to oxidized LDL (oxLDL), favoring foam cell formation and inflammation. Methods: Peritoneal macrophages were isolated from WT and CD73 LOF mice (n=4/genotype), then treated with 20 µg/ml oxLDL for 8 hours. RNA was extracted and sequenced (Illumina NovaSeq). DESeq2 was used for normalization and differential expression analysis; significance was set at P <0.05. Results: oxLDL exposure altered gene expression profiles differently between genotypes, especially in cholesterol metabolism. Thirty-one genes responded uniquely in one genotype. In WT macrophages, Cd36 was upregulated ( P =0.0305) and Srebf2 downregulated ( P =0.0343). In CD73 LOF cells, Gpr137b-ps (autophagy inhibitor, P =0.0417) and proinflammatory, proatherogenic Treml4 ( P =0.0110) were increased. WT-specific pathways involved lipid clearance and storage, while CD73 LOF macrophages lacked these responses. Conclusions: CD73 LOF macrophages showed proatherogenic phenotype with impaired lipid handling and a gene expression profile favoring atherosclerosis. These findings highlight a novel role for CD73 in regulating macrophage responses to lipid stress.