Class III Alcohol Dehydrogenase Plays a Key Role in the Onset of Alcohol-Related/-Associated Liver Disease as an S-Nitrosoglutathione Reductase in Mice

Lipid accumulation in the liver due to chronic alcohol consumption (CAC) is crucial in the development of alcohol liver disease (ALD). It is promoted by the NADH/NAD ratio increase via alcohol dehydrogenase (ADH)-dependent alcohol metabolism and lipogenesis increase via peroxisome proliferator-activated receptor ? (PPAR?) in the liver. The transcriptional activity of PPAR? on lipogenic genes is inhibited by S-nitrosylation but activated by denitrosylation via S-nitrosoglutathione reductase (GSNOR), an enzyme identical to ADH3. Besides ADH1, ADH3 also participates in alcohol metabolism. Therefore, we investigated the specific contribution of ADH3 to ALD onset. ADH3-knockout (Adh3-/-) and wild-type (WT) mice were administered a 10% ethanol solution for 12 months. Adh3-/- exhibited no significant pathological changes in the liver, whereas WT exhibited marked hepatic lipid accumulation (p < 0.005) with increased serum transaminase levels. Adh3-/- exhibited no death during CAC, whereas WT exhibited a 40% death. Liver ADH3 mRNA levels were elevated by CAC in WT (p < 0.01). The alcohol elimination rate measured after injecting 4 g/kg ethanol was not significantly different between two strains, although the rate was increased in both strains by CAC. Thus, ADH3 plays a key role in the ALD onset, likely by acting as GSNOR.