Cholesterol lowering depletes atherosclerotic lesions of smooth muscle cell-derived fibromyocytes and chondromyocytes.

Drugs that lower plasma apolipoprotein B (ApoB)-containing lipoproteins are central to treating advanced atherosclerosis and provide partial protection against clinical events. Previous research showed that lowering ApoB-containing lipoproteins stops plaque inflammation, but how these drugs affect the heterogeneous population of plaque cells derived from smooth muscle cells (SMCs) is unknown. SMC-derived cells are the main cellular component of atherosclerotic lesions and the source of structural components that determine the size of plaques and their propensity to rupture and trigger thrombosis, the proximate cause of heart attack and stroke. Using lineage tracing and single-cell techniques to investigate the full SMC-derived cellular compartment in progressing and regressing plaques in mice, here we show that lowering ApoB-containing lipoproteins reduces nuclear factor kappa-light-chain-enhancer of activated B cells signaling in SMC-derived fibromyocytes and chondromyocytes and leads to depletion of these abundant cell types from plaques. These results uncover an important mechanism through which cholesterol-lowering drugs can achieve plaque regression.