GSE163519
The fibrous cap of atherosclerotic lesions arise from multiple cellular origins by PDGFRB- and bioenergetic mechanisms
Stable atherosclerotic plaques are characterized by a thick extracellular matrix (ECM)-rich fibrous cap populated by protective ACTA2+ myofibroblast (MF)-like cells, assumed to be almost exclusively derived from smooth muscle cells (SMC). Herein, we show that in murine and human lesions, ~20-40% of ACTA2+ fibrous caps cells, respectively, are derived from non-SMC sources, including endothelial cells (EC) or macrophages that have undergone Endothelial-to-Mesenchymal (EndoMT) or Macrophage-to-Mesenchymal (MMT) transitions. In addition, weshow that SMC-specific knockout of the platelet-derived growth factor receptor beta (PDGFRB) in Apoe-/- mice fed a Western diet (WD) for 18 weeks results in brachiocephalic artery (BCA) lesions nearly devoid of SMC. While absence of SMCs does not affect lesion size, remodeling, or ACTA2+ fibrous cap cell content, prolonged WD feeding results in reduced indices of stability, indicating that EndoMT and MMT-derived MFs cannot compensate indefinitely for loss of SMC-derived MFs. Using RNA-seq analysis of the BCA region and in vitro models, we demonstrate that SMC to MF transitions (SMC-MFT) is induced by PDGF and TFGß and is dependent on aerobic glycolysis, while EndoMT is induced by IL1ß and TGFß. Together, we provide the first quantitative evidence that the ACTA2+ fibrous cap originates from a tapestry of cell types, which transition to an MF state through distinct signaling pathways that are either dependent on or associated with extensive metabolic reprogramming. Overall design: scRNA-seq of atherosclerotic plaques of Apoe-/- mouse (with or without specific SMC KO of PDGFRB)