Oxidative stress in alcoholic liver disease

A large body of clinical and experimental studies implicates free radical mechanisms in the pathogenesis of alcoholic liver disease (ALD). Ethanol-induced oxidative stress is the results of the combined impairment of antioxidant defenses and the stimulation of reac¬tive oxygen species (ROS) production by the mitochondrial electron transport chain, the alcohol-inducible cytochrome P4502E1 (CYP2E1) and activated phagocytes. Furthermore, hydroxyethyl free radicals (HER) are also generated during ethanol metabolism by CYP2E1. The mechanisms by which oxidative stress contributes to alcohol toxicity involve mitochondrial permeability transition, endoplasmic reticulum stress and impairment of hepatocyte pro-survival signals. Moreover, oxidative mechanisms contribute to the stimulation of hepatic inflammation by directly stimulating phagocyte activation and by promoting adaptive immune responses. Finally. oxidative stress favors the evolution of ALD to liver fibrosis by promoting the release of pro-fibrotic cytokines and the activation of hepatic stellate cells. Altogether these observations give a rationale to the possible clinical application of antioxidants in the therapy of ALD.