Abstract 18799: Edn1 is a Disease-Specific Marker in Endothelial Cells During Atherosclerosis

Abstract

Introduction: Coronary artery disease (CAD) is the leading cause of mortality in the United States. Multiple cell types contribute to the atherosclerotic plaques causing CAD, influencing its growth and propensity to rupture. Endothelial-to-mesenchymal transition (EndMT), the process by which endothelial cells (ECs) acquire characteristics of mesenchymal cells and loose canonical endothelial features, is correlated with an unstable plaque phenotype, although this transition remains poorly characterized. Hypothesis: A specific population of ECs may undergo EndMT, potentially contributing to the progression of atherosclerosis. Methods: We induced endothelial-specific lineage-tracing in Tg Cdh5-CreERT2 , ApoE -/- mice, followed by 16 weeks of high-fat diet (HFD) to produce atherosclerosis. Aortic roots were collected from male and female disease-condition animals (n=13) and a baseline cohort that was not fed HFD (n=6). Single cell RNA sequencing was performed and analyzed using the Seurat package. RNAscope staining of transverse sections (n=10 per genotype per sex) was performed to characterize the lesion. Results: We identified multiple endothelial subtypes within the aortic root. One population, characterized by the marker Klk10, appears to give rise to a disease-specific population characterized by expression of Edn1. Upstream regulator analysis of differentially expressed genes between Edn1+ and Klk10+ populations predict this EC transition to be driven by EndMT-associated transcription regulators including SNAI2, TWIST2, STAT3, SNAI1, YAP1, and TEAD2. This analysis also predicted upregulation of pulmonary fibrosis idiopathic signaling, wound healing signaling, pathogen induced cytokine storm signaling, and hepatic fibrosis signaling pathways. This EndMT process, characterized by a single, linear trajectory, was the only disease-associated EC transition state identified in the atherosclerotic aortic root. Conclusions: We identified ECs undergoing EndMT in a mouse model of atherosclerosis and determined that this transition is the primary EC cell state transition during disease. We localized this process in situ in the atherosclerotic lesion and identified potential key transcriptional drivers of this process.