急性肝衰竭小鼠肠道微生态的变化

Changes in the composition of intestinal microbiota in mice with acute liver failure induced by D-galactosamine

目的探讨急性肝衰竭小鼠肠道微生态菌群的变化情况，寻找特征性差异菌，为急性肝衰竭肠道微生态紊乱的诊治提供依据。方法BALB／c无特殊病原级雄鼠30只（空白组5只，模型组25只），D-氨基半乳糖制备小鼠急性肝衰竭模型。提取小鼠下消化道不同节段（回肠、结肠）内容物及粪便的微生物DNA，进行PCR扩增，对16SV3-V4区进行高通量测序，用生物信息学分析技术对测序结果进行OTU聚类、物种注释、α多样性分析、LEfSe（LDA Effect Size）分析，最终找到模型组特征性差异菌。两组间计量资料采用t检验。结果两组小鼠，共存活10只，其中模型组病死率为80％。与对照组比较，α多样性分析显示急性肝衰竭小鼠回肠中细菌丰度和多样性增加；结肠中细菌丰度减低但多样性增加；粪便中细菌多样性降低，丰度差异无统计学意义。在最佳分类水平上，回肠梭菌科丰度减少（44．95％±19．28％与7．51％±16．57％，t=3．293），而结肠理研菌科（1．08％±1．01％与4．18％±2．39％，t=-2．669）、S24-7（4．75％±4．87％与22．77％±13．05％，t=-2．890）、F16（0．24％±0．28％与2．19％±1．61％，t=-2．656）等丰度增加，P值均〈0．05。LEfSe（LDA Effect Size）分析显示两组在葡萄球菌科、S24-7方面差异有统计学意义，其中S24-7可定义为特征性差异菌群。结论急性肝衰竭小鼠肠道微生态紊乱，回肠菌群过度生长。急性肝衰竭与S24-7过度生长相关。

Objective To investigate the changes in the composition of intestinal microbiota in mice with acute liver failure and identify characteristic bacteria, and to provide a basis for the diagnosis and treatment of acute liver failure with intestinal microbiota disorders. Methods A total of 30 specific pathogen- free male BALB/c mice were used in this study, including 25 mice in the model group and 5 mice in the control group. An acute liver failure model was induced by D-galactosamine. Microbial DNA was extracted from intestinal contents in different segments of the lower digestive tract （ileum and colon） and feces and then were amplified using PCR. The regions of 16S V3-V4 were subjected to high-throughput sequencing, followed by bioinformaties analyses, including OTU hierarchical clustering, species annotation, alpha- diversity analysis, and LEfSe （LDA Effect Size） analysis. Comparison of continuous data was made using t-test, while comparison of categorical data was made using Z2 test. Results A total of 10 mice survived in the two groups, with 80% mortality rate in the model group. The alpha-diversity analysis revealed increased bacterial diversity and abundance in the ileum, increased bacterial diversity and reduced bacterial abundance in the colon, and reduced bacterial diversity and insignificantly changed bacterial abundance in feces in the model group compared with the control group. Based on the optimized classification level, significantlyreduced abundance of Clostridiaceae （44.95% ± 19.28% vs 7.51% ± 16.57%, P = 0.011） in the ileum, whereas significantly increased abundance of Rikenellaceae （1.08% ± 1.01% vs 4.18% ± 2.39%, P = 0.028）, S24-7 （4.75% ± 4.87% vs 22.77% ± 13.05%,P = 0.020）, and F16 （0.24% ± 0.28% vs 2.18% ± 1.61%,P = 0.029） in the colon were found in model group compared with the control group. The LEfSe 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 bacteria. Conelnsion Intestinal microbiota disorders, especially the excessive growth of microbes in the ileum, are observed in mice with acute liver failure. Moreover, acute liver failure may be closely associated with the excessive growth of S24-7.