Lactic Acid Bacteria Exert a Hepatoprotective Effect against Ethanol-Induced Liver Injury in HepG2 Cells

Alcoholic liver fatty disease (ALFD) is caused by excessive and chronic alcohol consumption. Alcohol consumption causes an imbalance in the intestinal microflora, leading to liver disease induced by the excessive release of endotoxins into the hepatic portal vein. Therefore, research on the intestinal microflora to identify treatments for ALFD is increasing. In this study, the protective effects of lactic acid bacteria (LAB) strains, including Levilactobacillus brevis, Limosilactobacillus reuteri, and Limosilactobacillus fermentum, were evaluated in ethanol-induced HepG2 cells. Among the evaluated LAB, nine strains increased aldehyde dehydrogenase (ALDH) levels and downregulated lipid peroxidation and liver transferase in the ethanol-induced HepG2 cells. Moreover, L. brevis MG5280 and MG5311, L. reuteri MG5458, and L. fermentum MG4237 and MG4294 protected against ethanol-induced HepG2 cell damage by regulating CYP2E1, antioxidant enzymes (SOD, CAT, and GPX), lipid synthesis factors (SREBP1C and FAS), and lipid oxidation factors (PPARα, ACO, and CPT-1). Moreover, five LAB were confirmed to be safe probiotics based on antibiotic susceptibility and hemolysis assays; their stability and adhesion ability in the gastrointestinal tract were also established. In conclusion, L. brevis MG5280 and MG5311, L. reuteri MG5458, and L. fermentum MG4237 and MG4294 may be useful as new probiotic candidates for ALFD prevention.