Differential effects of traditional cigarette, electronic cigarette, and tobacco heating product on human vascular smooth muscle cell phenotypic switch: A comparative functional perspective

Background and aims: Vascular smooth muscle cell (SMC) phenotypic switching, from a contractile to a synthetic state, impacts on atherosclerotic plaque development. While traditional cigarette (TC) smoke is a known driver of cardiovascular disease, the effects of alternative nicotine delivery systems, i.e. electronic cigarettes (E-cigs) and tobacco heating products (THPs), on SMC behavior remains poorly understood. We evaluated the effects of water-soluble components collected in aqueous extracts (AEs) from TC, E-cig, and THP smoke, on human aortic SMC (HASMC) phenotypic switch. Methods: HASMCs were treated for 48 h with the three AEs. Gene expression and protein abundance profiles were assessed to evaluate cell phenotypic modulation, proliferation, migration, extracellular matrix remodeling, and inflammatory responses. Label-free MS/MS proteomic analysis and wound healing assays were also used to further characterize cellular responses. Results: Different AEs induced distinct gene expression and protein patterns, but all seemed to induce a hybrid contractile-synthetic phenotype. TC and THP extracts increased MMP3 expression, whereas E-cig AE downregulated MMPs. E-cig extracts, although reducing inflammatory cytokines, enhanced HASMC proliferation and migration, bona fide by upregulating PCNA, RAC1, and ROCK2, thus suggesting an increased vascular remodeling. Proteomic analysis indicated mitochondrial dysfunction and redox imbalances further advising about distinct, harmful effects of AEs on vascular health and atherosclerotic lesion progression. Conclusion: Our findings revealed complex differential molecular effects of TC, E-cig, and THP AEs on HASMC biology, emphasizing the necessity for further research to assess their actual long-term cardiovascular implications.