Study On The Dysbiosis Of Intestinal Microbiota In Mice With D-galactosamine-induced Acute Liver Failure

Objective: To investigate the alterations of intestinal microbial flora in mice with acute liver failure,and to find out the characteristic differential bacteria,and thus to provide the basis for diagnosis and treatment of intestinal microecological disorders in acute liver failure.Methods: thirty male BALB/c mice with 25 in model group and 5 in the control group,were enrolled in this study.Acute liver failure was induced by D-galactosamine in model group.The microbial DNA extracted from intestinal contents and feces taken from different segments(ileum,colon)of BALB/c mouse's lower digestive tract was amplified by PCR.The sequences of regions 16 S V3-V4 were sequenced and analyzed using bioinformatical techniques including OTU hierarchical clustering,species annotation,alpha-diversity analysis,and LEfSe(LDA Effect Size)analysis,in order to find out the characteristic differential bacteria in model group.Results: A total of 10 mice survived in the two groups,with the mortality rate of the model group being 80%.30 samples were obtained from the contents and feces of ileum and colon.The sequencing coverage depth is over 97%.Alpha-diversity analysis revealed increased bacterial diversity(shannon index2.5±0.1vs2.8±0.8,P<0.05)and decresed bacterial abundance(chao1 index105.7±18.4vs149.3±55,P<0.01)in the ileum;decreased bacteial diversity and increased bacterial abundance(chao1 index 285.4±46.1vs276.98±46.7,P<0.05)in the colon while decreased bacterial diversity(shannon index 4.9±0.3vs5.65±0.39,P<0.01 Shannon index,P<0.01);decreased bacteial diversity(shannon index5.1±0.3vs4.87±0.29,P<0.01)and non statistical differente bacterial abundance(chao1index 270.1±53.7vs250.2±54.4,P=0.067)in the feces,in acute liver failure mice.We got 10 phylum in the end.The intestinal flora of mice was mainly composed of Firmicutes,Bacteroidetes and Proteobacteria,but in mice with acute liver failure,there was no statistically significant difference in the ileum.Results showed that the proportion of Bacteroidetes markedly increased(9.3%±7.9%vs33.8%±18.2%,t=-2.768,P=0.024<0.05),and the proportion of TM7 phylum was revealed enhanced(0.2%±0.3%vs2.2%±1.6%,t=-2.657,P=0.029<0.05);in the colon of mice with acute liver failure.Meanwhile,the proportion of Firmicutes in the feces decreased(32.8%±20.5%vs10.2%±5.5%,t=2.381,P=0.05),while the proportion of Bacteroidetes increased without significant difference(57.3%±23.4%?86.1%±67.2%,P=0.07).Based on the optimized classification level,the abundance of Clostridaceae(44.95%±19.28%?7.51%±16.57%,P <0.05)in the ileum decreased,but the abundance of Rikenellaceae(1.08%±1.01%?4.18%±2.39%,P <0.05),S24-7(4.75%±4.87%?22.77%±13.05%,P <0.05),and F16(0.24%±0.28%?2.18%±1.61%,P <0.05)in the colon increased,with markedly statistical significance.LEfSe(LDA Effect Size)analysis demonstrated that there were significant differences in Staphylococcaceae and S24-7 between the two groups,and S24-7 could be defined as the characteristic differential bacteria.Conclusion: Different segments of the intestine have different intestinal flora structure.Intestinal microecological disorders,especially the excessive growth of microbes in the ileum.Acute liver failure was closely associated with the excessive growth of S24-7.