Easwaran, M. | bioRxiv Science

bioRxiv2025

Chronic Electronic Cigarette Exposure Promotes Atherosclerosis and Chondrogenic Modulation of Smooth Muscle Cells

BackgroundElectronic cigarette (E-cig) use has reached epidemic proportions worldwide, yet its cardiovascular consequences remain poorly defined. While several lines of evidences in human epidemiological and animal studies suggest chronic aerosol exposure accelerates atherosclerosis; the cellular and molecular mechanisms underlying this pathological remain unknown. MethodsWe exposed hyperlipidemic mice to chronic e-cigarette aerosol inhalation and characterized the plaque cellular landscape by coupling SMC lineage tracing with single-cell transcriptomic/epigenomic profiling and histologic phenotyping. We subsequently leveraged human coronary artery smooth muscle cells (HCASMCs) to validate in vivo discovery and identified E-cig specific pathological signaling pathways relevant to human vascular disease risk. ResultsChronic E-cig aerosol exposure accelerated atherosclerosis, increasing both SMC phenotypic modulation and plaque macrophage burden in a lipid-independent manner. Transcriptomically, SMCs are particularly more sensitive to E-cig than other vascular cell types. E-cig exposure reprogrammed SMCs toward a pro-calcifying, chondrogenic phenotype, thereby enhancing vascular ossification in vivo and in HCASMCs in vitro. Mechanistically, E-cig mediated SMC fate alteration occurs through activation of a glutamatergic/NMDAR signaling program, that increased NMDAR-dependent Ca2+ influx in a GRIN2A dependent manner. Notably, inhibition of GRIN2A mediated signaling reversed E-cig-induced pathological shifts in SMC phenotype. ConclusionsSMC chondrogenic reprogramming and subsequent vascular calcification are central to the detrimental cardiovascular consequences of E-cig exposure. Our findings implicate a GRIN2A-dependent glutamatergic/NMDAR signaling axis in SMC as a primary driver of this calcifying remodeling program. These findings define a SMC-specific vulnerability to E-cig aerosols and establish the GRIN2A/NMDAR pathway as potential therapeutic targets for mitigating E-cig-associated cardiovascular disease.

genomics↗

bioRxiv2024

Aryl-hydrocarbon receptor in smooth muscle cells protect against dioxin induced adverse remodeling of atherosclerosis

IntroductionEnvironmental exposure to dioxin has been linked to increased myocardial infarction. Smooth muscle cells (SMC) in the coronary vasculature play a critical role in atherosclerotic plaque remodeling due to their phenotypic plasticity, however, the detailed mechanism linking dioxin exposure to adverse SMC modulation is not well understood. MethodsSingle-cell RNA and ATAC sequencing and histological analyses were performed on the aorta from mouse models of atherosclerosis exposed to 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) or control. Primary human coronary artery SMC (HCASMC) treated in culture with TCDD were used to perform RNA-Seq, ATAC-Seq, and functional phenotypic assays. ChIP-Seq was performed with antibodies against Aryl-hydrocarbon receptor (AHR) and TCF21, two of known SMC modulating transcription factors. ResultsModulated SMC were the most transcriptionally responsive cell type to dioxin in the atherosclerotic aorta. Dioxin accelerated disease phenotype by promoting a modulated SMC phenotype early, resulting in increased lesion size, migration of SMC, and macrophage recruitment to the lesion. We found C3 expressing modulated SMCs to be likely contributing to the increased macrophage recruitment and inflammation. Analysis of the RNA-Seq data from HCASMC treated with TCDD showed differential enrichment of biological pathways related to cell migration, localization, and inflammation. Furthermore, ATAC-Seq data showed a significant activation for pathways regulating vascular development, cell migration, inflammation, and apoptosis. With TCDD treatment, there was also enrichment of AHR ChIP-Seq peaks, while the TCF21 enrichment decreased significantly. The SMC-specific Ahr knockout resulted in increased oxidative stress in SMC, increased lesion size and macrophage content, and loss of SMC lineage cells in the lesion cap when exposed to TCDD, consistent with a more vulnerable plaque phenotype. ConclusionDioxin adversely remodels atherosclerotic plaque by accelerating the SMC- phenotypic modulation, and increasing inflammation and oxidative stress resulting in increased macrophage recruitment and lesion size. Dioxin may adversely affect the SMC phenotype and disease state by affecting the TCF21 occupancy in the open chromatin regions. Furthermore, we observed that SMC-specific deletion of Ahr in mice resulted in worsening of dioxin mediated SMC modulation and atherosclerosis, suggesting that Ahr in SMC confers protection against dioxin by promoting a stable plaque phenotype and reducing dioxin induced oxidative stress. SummaryO_LIExposure to dioxin, an environmental pollutant present in tobacco smoke and air pollution, accelerates smooth muscle cell modulation, and atherosclerosis. C_LIO_LIDioxin exposure leads to inflammatory smooth muscle cell phenotype characterized by complement pathway activation and increased macrophage recruitment to plaque C_LIO_LIAryl-hydrocarbon receptor in SMC protects against oxidative stress, and promotes a stable plaque phenotype C_LI

molecular biology↗