Sexually dimorphic transdifferentiation of endothelial cells in atherosclerosis

Sex differences in atherosclerosis are clinically recognized, but the contribution of endothelial cell (EC) states and fates to these differences remain incompletely understood. Here, we used EC lineage tracing in male and female Apoe −/− /Cdh5-CreER T2 /Rosa26-mTmG mice fed a high-fat diet and performed single-nucleus RNA sequencing of plaque-bearing aortae. We identified nine sex-biased EC subpopulations, including capillary, lymphatic, Sox17 + , Myh11 + , Mki67 + , and Ly6a + ECs enriched in females and Col8a1 + and Fmo2 + ECs enriched in males. GeneTrajectory analysis and lineage tracing indicated that approximately one quarter of GFP⁺ EC-lineage cells transit into adipocyte-like, SMC-like, or fibroblast-like states. EC-to-SMC-like transitions were more prominent in females, whereas EC-to-adipocyte-like transitions were more prominent in males. Regulatory network analysis using pySCENIC implicated Klf2 and Creb5 in EC fate decisions. These findings reveal sex-specific EC-lineage trajectories associated with distinct plaque phenotypes and nominate candidates for sex-informed therapeutic investigation.