Study On The Protective Effect And Mechanism Of Gluconobacter Xylinum On Alcoholic Liver Injury

Alcoholic liver disease(ALD)is caused by alcohol abuse and occurs after years of excessive drinking.Oxidative stress and ALD induced by long-term intake of alcohol are serious public health concerns.No current drug therapy provides the ideal effects of preventing liver fibrosis while simultaneously treating ALD.Potentiality of probiotics for exploitation as functional foods has also been reported.The probiotics and probiotic products are widely used in promoting human health and adjunctive therapy of ALD.Therefore,this study was to investgate antioxidant activity of Komagataeibacter hansenii CGMCC 3917 in vitro and a mouse model of chronic alcohol consumption in vivo was employed.Correlative biochemical parameters of hepatic inflammatory cytokines and intestinal flora changes were measured to investigate the protective effects of K.hansenii CGMCC 3917 against oxidative stress and chronic alcohol-induced liver injury in mice.The main findings are as follows.1.The antioxidant properties of K.hansenii CGMCC 3917 intact and fragmented bacteria cells were determined in vitro.K.hansenii CGMCC 3917 were cultured in fermentation medium and subcultured to insure the identity of bacterial growth.The antioxidant activities of bacteria cells were determined by measuring scavenging activities against DPPH,ABTS and hydroxyl free radicals and total reducing power,where both the intact and fragmented bacteria cells were prepared for comparison.The antioxidant activity of acetic acid bacteria CGMCC 3917 in vitro was higher than that of physically broken bacteria cells.Results of in vitro measurement revealed that CGMCC 3917 exhibited powerful antioxidant abilities and the intact cells showed higher effect than that of fragmented bacteria(p<0.05).2.The animal experiments showed that 28%ethanol exerted severe liver injury in mice which was prevented by CGMCC 3917.In vivo supplementation of mice with CGMCC 3917 bacteria suspension at a dose of 10 mL/kg(108 or 106 CFUs/mL)dramatically decreased the elevated serum activities of aspartate aminotransferase(AST)and alanine aminotransferase(ALT)induced by alcohol treatment in mice(p<0.01),and also significantly decreased the elevated levels of alkaline phosphatase(ALP).Meanwhile,CGMCC 3917 was effective to mitigate oxidativess and liver inflammation by increasing SOD GSH-Px activities,and reducing MDA concentration,while inhibiting inflammatory cytokine such as IL-1,IL-6 and TNF-a expressing in ethanol-treated mice.Liver histopathological examination using H&E and Oil red O staining method was consistent with the biochemical results suggesting that CGMCC 3917 could significantly mitigate severe pathological liver damage induced by ethanol.3.The results showed that ehanol-induced metabolic disorders of fatty acid in mice were effectively attenuated by intervention of CGMCC 3917.CGMCC 3917 treated mice showed the lower activities of FAS,ACC and SCD-1,and higher levels of HDL-C when compared with ethanol mice.Meanwhile,administration of CGMCC 3917 effectively reduced the serum TC,TG and LDL-C levels in mice treated 28%ethanol,suggesting that CGMCC 3917 could alleviate the dyslipidemia induced by ethanol.4.High-throughput sequencing based on 16S rRNA was used to investigate the structural changes of intestinal flora.Results revealed that 28%ethanol could disrupt the ecological balance of the normal microflora and gut epithelial barrier function in mice,leading to transferation of endotoxin(LPS)into the blood circulation.Results revealed that 28%ethanol induced a significant increase in proportions of the phylum Proteobacteria,phylum Actinobacteria,phylum Firmicutes and genus Helicobactor,but decreased numbers of the phylum Bacteroidetes with reduced proportion of genus Lactobicillus.Interestingly,CGMCC 3917 treatment reduced the relative abundance of phylum Bacteroidetes,Proteobacteria and Actinobacteria,and increased the relative abundance of Lactobicillus.All these results indicated that CGMCC 391 7 could reverse the ethanol-induced changes of intestinal microflora in mice,and adjust the composition of intestinal flora of the mice treated with 28%ethanol similar to that of the normal mice.All these findings suggest that Komagataeibacter hansenii CGMCC 3917 may be a great potential natural food resource against chronic alcohol-induced liver injury in mice.Furthermore,this study will provide experimental evidence for the exploitation of liver protective functional foods containing acetic acid bacteria.