Chronic ethanol exposure induces cardiac fibroblast transdifferentiation via ceramide accumulation and oxidative stress

Excessive alcohol consumption is associated with cardiac dysfunction and the development of myocardial fibrosis. In this study, we aimed to investigate the direct impacts of ethanol on myocardial fibroblasts and elucidate the underlying mechanism responsible for chronic ethanol-induced myocardial fibrosis. Rat primary cardiac fibroblasts exposed to ethanol for 24 h and C57BL/6J mice fed on Lieber–DeCarli diet to establish an ethanol intoxication model in vitro and in vivo, respectively. Histological analyses, molecular biology techniques, and analytical chemistry methods were then conducted. In vivo and vitro experiments revealed that chronic ethanol exposure induced increased myocardial fibrosis and augmented the transdifferentiation of myocardial fibroblasts. Simultaneously, it elicited an upregulation in the production of long-chain and very-long-chain ceramides in cardiac fibroblasts. The excessive accumulation of ceramide leads to elevated levels of intracellular oxidative stress, culminating in the activation of TGF-β-SMAD3 signaling and the development of fibrosis. Intervention of these pathways with pharmacological inhibitors in vitro or in vivo inhibited fibrosis. In conclusion, ethanol increased ceramides and reactive oxygen species (ROS) in cardiac fibroblasts, resulting in the activation of TGF-β-SMAD3 signaling, transdifferentiation of fibroblasts, and myocardial fibrosis.