具核梭杆菌灌胃对大鼠肠道菌群的影响

Effects of Fusobacterium nucleatum gavage on the intestinal microbiota of rats

目的探究具核梭杆菌(Fusobacterium nucleatum)灌胃对健康大鼠肠道菌群的影响。方法将16只SD雄性大鼠随机分为2组(每组8只),处理组在大鼠第4、5、6、7、8周龄分别用具核梭杆菌灌胃1次,对照组在相同时间点以等量生理盐水灌胃。在大鼠第3、8、12周末收集粪便,提取DNA后通过Illumina Miseq平台进行16S rRNA基因高通量测序。应用蛋白印迹法检测大鼠粪便中针对具核梭杆菌的特异性IgA。结果第3周时,两组在菌群多样性、主要菌门水平方面的差异无统计学意义。第8周时,处理组菌群多样性明显低于对照组(P=0.009);处理组的厚壁菌门、变形菌门含量低于对照组,拟杆菌门含量高于对照组,差异均有统计学意义(P<0.05)。第12周时,处理组菌群多样性明显高于对照组(P=0.021),两组大鼠肠道菌群的主要菌门水平差异无统计学意义。同时,具核梭杆菌灌胃刺激机体产生了特异性IgA。结论具核梭杆菌通过未定植方式,对肠道菌群产生了影响,并可持续一定时间。具核梭杆菌刺激产生的特异性IgA可能是其不能在肠道定植的原因之一。

Objective To investigate the effects of Fusobacterium nucleatum（ F. nucleatum） gavage on the intestinal microbiota of rats. Methods A total of 16 male SD rats were randomly divided into 2 groups： intervention group（ n =8） and control group（ n = 8）. The intervention group was treated with F. nucleatum when the rats were 4,5,6,7 and8 weeks old. The control group was treated with the same dosage of normal saline at the same time. Feces was collected at the end of week 3,8 and 12 to extract DNA,and then Illumina Miseq platform was used for 16 S rRNA gene sequencing.Specific IgA against F. nucleatum in stool was detected with Western blotting. Results There were no significant differences between the two groups in terms of fecal microbial diversity and relative abundance of main phyla in week 3.The microbial diversity of the intervention group was significantly lower than that of the control group in week 8（ P =0.009）. The relative abundances of Firmicutes and Proteobacteriodes in the intervention group were significantly less than those in the control group（ P〈0.05）,while the relative abundance of Bacteriodes in the intervention group was significantly higher than that in the control group in week 8（ P〈0.05）. In week 12,the intervention group showed higher diversity（ P= 0.021）,and there was no significant difference in the relative abundance of main phyla. Moreover,the treatment of F. nucleatum stimulated the production of specific IgA. Conclusion The F. nucleatum can interfere with intestinal microbiota independent on colonization,and this effect can last for some time. The production of specific IgA induced by F. nucleatum may explain why this bacterium does not colonize in the intestine.