Abstract 12147: Flow-Induced Cellular Reprogramming in Mouse Atherosclerosis Model

Abstract

Introduction: Atherosclerosis, a leading cause of death worldwide, is a chronic inflammatory disease that occurs preferentially in the arterial regions exposed to disturbed flow (d-flow), while those exposed to stable flow (s-flow) are protected. Recently, we reported d- F low I nduced R eprogramming of E ndothelial cells (ECs) ( FIRE ), including endothelial inflammation, endothelial-to-mesenchymal transition (EndMT) and endothelial-to-immune-cell transition (EndIT). Hypothesis: D-flow plus hypercholesterolemia (HighChol) exacerbates reprogramming of arterial cells leading to atherosclerosis development compared to d-flow alone and HighChol alone. Methods: To test this hypothesis, we induced atherosclerosis in C57BL/6 mice by an AAV-PCSK9 injection and high-fat diet to induce HighChol and/or partial carotid ligation (PCL) surgery to expose left carotid artery (LCA) to d-flow compared to the right CA (RCA) exposed to s-flow. Single cells prepared from collagenase digestion of the LCAs and RCAs at 2 and 4 weeks post-PCL were analyzed by scRNA-seq and integrated with our prior scRNA-seq data obtained at 2 days and 2 weeks post-PCL under normal blood cholesterol levels. Results: Overall, our data showed that d-flow was the most predominant regulator of arterial cell characteristics while HighChol alone had relatively minor effects. In the RCA, homeostatic EC, smooth muscle cell (SMC), and macrophage (MΦ) clusters were dominant regardless of cholesterol levels. Additionally, for these cell types, we found clusters that increased in response to d-flow in the LCA, which further increased with HighChol and time. Surprisingly, diffusion map trajectory analysis revealed a clear convergence of transcriptomic profiles of EndIT ECs, SMC-derived foam cell SMCs, and foamy MΦs. Conclusions: These results suggest FIRE initiated by d-flow is exacerbated by HighChol. We also found that SMCs and MΦs transition toward proatherogenic phenotypes under d-flow, which is further exacerbated by HighChol. Furthermore, differential gene expression analysis showed that proatherogenic ECs, SMCs, and MΦs show common transcriptomic profiles, suggesting common set of genes and pathways that could be targeted as effective atherosclerotic therapeutics.