Atherosclerosis Profiling Reveals BHLHE40 as a Candidate Modulator of VSMC.

BACKGROUND

Vascular smooth muscle cells (VSMCs) play a central role in atherosclerosis by undergoing phenotypic modulation from a quiescent, contractile state to a range of synthetic phenotypes, including fibroblast-like, macrophage-like, and lipid-laden foam cell-like states. However, a comprehensive multimodal characterization and understanding of the transcriptional programs driving these transitions remain incomplete.

METHODS

To comprehensively define the phenotypic diversity of VSMCs during atherosclerosis progression, we performed in-depth profiling using cellular indexing of transcriptomes and epitopes by sequencing and bulk RNA sequencing in a VSMC-lineage-tracing atherosclerotic mouse model. Insights from these data sets guided the design of targeted in vitro experiments to investigate candidate regulatory mechanisms.

RESULTS

Single-cell multiomics revealed extensive cellular heterogeneity within atherosclerotic plaques, including a rare population of VSMC-derived macrophage-like cells, whose presence was confirmed by histological analysis. These studies also identified a large population of VSMC-derived foam cells that exhibited activation of gene programs associated with lipid metabolism, proliferation, and tumor-like features. The transcription factor BHLHE40 (basic helix-loop-helix family member e40) emerged as a candidate regulator of this phenotypic transition, with elevated expression and activity in VSMC-derived foam cells during disease progression and expression in modulated VSMC in human carotid atherosclerosis. Functional knockdown of Bhlhe40 reprogrammed immune, cell cycle, and lipid homeostasis genes in cultured VSMC and suppressed VSMC phenotypic switching and foam cell characteristics, consistent with a potential regulatory role in VSMC modulation.

CONCLUSIONS

These findings advance our understanding of VSMC phenotypic modulation in atherosclerosis and implicate BHLHE40 as a candidate transcriptional regulator of this process. Elucidating mechanisms governing VSMC plasticity may offer new therapeutic opportunities to reduce cardiovascular risk by targeting disease-driving cellular transitions.