CEBPB drives endothelial pathological phenotype and promotes atherosclerosis by directly upregulating TGFBR1 expression [scRNA-seq]

Endothelial cell (EC) dysfunction is crucial in chronic vascular inflammation and diseases like atherosclerosis. An unknown endothelial pathological phenotype potentially driving atherosclerosis was hinted in our previous study. However, the detailed characterizations and underlying molecular mechanisms remain unclear. Here, we have defined a new endothelial pathological phenotype, characterized by high expression of fibroblast and pro-inflammatory genes with a rapid reduction in EC fate genes by performing single-cell RNA sequencing. Further analysis revealed that increased CEBPB contributes to the fibroblast and inflammatory feature of these atherogenic ECs, which was further confirmed in cultured human aortic ECs. Mechanistically, IL-1ß-induced high expression of CEBPB triggers TGF-ß signaling and subsequent regulation of downstream genes. This occurs through direct interaction of CEBPB with the promotor region of TGF-ß receptor type I (TGFBR1), resulting in its upregulation. Furthermore, exacerbating atherosclerotic plaque area, enhanced vascular inflammation and increased endothelial TGFBR1 expression were confirmed by endothelial overexpression of CEBPB in vivo. These findings suggest endothelial CEBPB functions as a novel regulator of TGFBR1, driving endothelial pathological phenotype, promoting vascular inflammation and atherosclerosis. Targeting endothelial CEBPB may offer new therapeutic avenues for atherosclerotic diseases. Overall design: We performed scRNA-Seq analysis of ECs from normal aortas (i.e., from C57BL/6 mice fed on a standard diet), mild atherosclerotic aortas (i.e., from Apoe-/- mice fed on a standard diet), and severe atherosclerotic aortas (i.e., from Apoe-/- mice fed on a high fat diet)