大肠杆菌感染对小鼠肠道微生物群变化及抗微生物肽表达的影响

Effects of E.coli Infection on Changes of Intestinal Microbiota and Expression of Antimicrobial Peptides in Mice

目的:探讨大肠杆菌感染对小鼠肠道微生物群变化及抗微生物肽表达的影响。方法:6-8周龄SPF级健康雄性C57BL/6小鼠20只,随机分为E.coli O_(1)组和对照组,每组10只。收集小鼠盲肠内容物,进行16S rRNA测序,采用OTU聚类分析、Alpha多样性分析、门水平差异分析等方法分别对两组小鼠肠道菌群的多样性、丰度和物种组成进行研究;HE染色观察小鼠空肠、回肠和十二指肠组织病理学变化;采用Western blotting和RT-PCR检测回肠内容物Reg3γ和S100A8、脂质运载蛋白-2蛋白和mRNA表达水平。结果:与对照组比较,E.coli O_(1)组OUT、Chao1及ACE-指数均明显降低(P<0.05);在门水平上,E.coli O_(1)组的拟杆菌门丰度降低(P<0.05),变形菌门的丰度升高(P<0.05);E.coli O_(1)组回肠内容物Reg3γ、S100A8、脂质运载蛋白-2水平较对照组显著升高(P<0.05);E.coli O_(1)感染导致小鼠肠组织显著病理损伤。结论:大肠杆菌(E.coli O_(1))感染能显著降低盲肠内菌群多样性,刺激小鼠肠道抗微生物肽的表达。

Objective:To investigate the effects of Escherichia coli infection on intestinal microbiota and antimicrobial peptide expression in mice.Methods:Twenty healthy SPF male C57BL/6 mice aged 6-8 weeks were randomly divided into E.coli O1 group and control group,with 10 mice in each group.The cecum contents of mice were collected for 16S rRNA sequencing.OTU cluster analysis,Alpha diversity analysis and gate level difference analysis were used to study the diversity,abundance and species composition of intestinal microflora in the two groups.The histopathological changes of jejunum,ileum and duodenum were observed by HE staining.Western blotting and RT-PCR were used to detect the expression levels of Reg3γ,S100A8,lipid carrier protein-2 protein and mRNA in ileal contents.Results:Compared with control group,the OUT,Chao1 and ACE-indices of E.coli O_(1) group were significantly decreased(P<0.05).At the phylum level,the abundance of Bacteroidetes in E.coli O_(1) group was decreased(P<0.05),while the abundance of Proteobacteria was increased(P<0.05).The levels of Reg3γ,S100A8 and lipid carrier protein-2 of ileal contents in E.coli O1 group were significantly increased compared with those in control group(P<0.05).E.coli O_(1) infection caused significant pathological damage to normal tissue in mice.Conclusion:E.coli O_(1) infection can significantly reduce the diversity of cecum flora and stimulate the expression of intestinal antimicrobial peptides in mice.