A biphasic effect of alcohol on endothelial plasticity through regulation of endothelial-to-mesenchymal transition

Alcohol influences cardiovascular disease, but whether it does so by affecting endothelial plasticity is unknown. We tested whether alcohol regulates endothelial-to-mesenchymal transition (EndMT) to influence arterial pathology. Human coronary artery endothelial cells (HCAEC) and human umbilical vein endothelial cells (HUVEC) were exposed to inflammatory cytokines or hypoxia in the absence or presence of ethanol (5-100 mM). In vivo, carotid ligation was performed in mice gavaged with/without either daily moderate ethanol (2 drinks equivalent/day) or episodic binge exposure (7 drinks equivalent, 2 days/wk) and myoendothelial cells assessed. Cytokines and hypoxia induced EndMT in vitro characterized by loss of endothelial markers, increased mesenchymal markers, and enhanced migratory capacity. Low-to-moderate-dose ethanol (5-25 mM) attenuated marker changes, preserving endothelial phenotype, whereas high-dose ethanol (50-100 mM) either had no effect or exacerbated EndMT. The inhibitory effect of moderate-dose ethanol on cytokine- and hypoxia-induced changes in α-smooth muscle actin (αSMA) and cadherin-5 (Cdh5) expression was abrogated by γ-secretase inhibition, consistent with involvement of Notch signaling. Carotid ligation induced neointimal formation and accumulation of myoendothelial cells indicative of EndMT. Daily moderate-dose ethanol significantly attenuated neointimal hyperplasia and diminished the myoendothelial cell population, whereas in contrast, episodic binge ethanol exposure increased pathologic remodeling and myoendothelial cell abundance. Alcohol modulates endothelial transdifferentiation in a biphasic manner. Low-to-moderate-dose alcohol exposure suppresses EndMT and limits pathological remodeling, whereas higher level binge exposure promotes these processes. These findings identify regulation of endothelial plasticity as a potential novel mechanism linking alcohol consumption patterns to vascular disease risk.NEW & NOTEWORTHY We identify a previously unrecognized biphasic effect of alcohol on endothelial phenotypic plasticity. Low-to-moderate-dose alcohol suppresses endothelial-to-mesenchymal transition (EndMT), whereas high-level (binge) exposure promotes this proatherogenic process. Given the central role of EndMT in vascular remodeling and atherosclerosis, these findings provide a mechanistic framework linking alcohol consumption and cardiovascular disease risk - potentially explaining both the protective effect at low-to-moderate levels, and the detrimental impact of heavy alcohol use.