Abstract Body (Do not enter title and authors here): Introduction:
Electronic cigarette use has emerged as a significant public health concern, particularly among adolescents and young adults. Epidemiological and experimental studies have linked e-cigarette use to accelerated atherosclerosis, but the underlying mechanisms remain poorly understood.
Methods:
To investigate the effects of chronic e-cigarette exposure on atherosclerotic lesion formation and vascular smooth muscle cell (SMC) phenotypic modulation, we utilized SMC lineage-tracing mice on an ApoE-null hyperlipidemic background (n=16 per group). Mice were exposed to pod-based e-cigarettes (Juul) three times weekly for 12 weeks in a whole-body exposure chamber, while controls were exposed to filtered air. Aortic sinus tissues were harvested and analyzed using single-cell RNA sequencing (scRNA-seq) and assay for transposase-accessible chromatin sequencing (scATAC-seq) to profile gene expression and chromatin accessibility. Osteogenic activity was assessed histologically via alkaline phosphatase staining.
Results:
E-cigarette exposure significantly increased the proportion of SMCs undergoing phenotypic switching toward a chondrogenic-like phenotype, with elevated expression of Col2a1 and Tnfrsf11b. Histological analysis confirmed increased osteogenic activity in e-cigarette-exposed mice. Chromatin accessibility profiling identified a unique cellular cluster enriched for glutamatergic signaling pathways, including increased accessibility at Grin2a, the gene encoding the NMDA receptor subunit GluN2A. Grin2a expression was upregulated in SMCs from e-cigarette-exposed mice and in vitro human coronary artery SMCs treated with e-cigarette extract. Inhibition of GRIN2A signaling attenuated e-cigarette-induced SMC phenotypic switching, indicating that NMDAR activation plays a key role in this process.
Conclusion:
Chronic e-cigarette exposure promotes atherosclerosis by driving SMC phenotypic modulation toward a chondrogenic state. Our results identify GRIN2A and NMDAR signaling as a potential therapeutic target for mitigating cardiovascular risk associated with e-cigarette use.