characterization of gut microbiota profiles in nod2-/- and nod2+/+ mice and effect of genotype and environment on severity of colitis

In order to evaluate the effect of Nod2 genotype and environmental factors, such as gut microbiota composition in the previously observed response to experimental induced-colitis, we performed meta-taxonomic analysis of gut microbiota in Nod2-/- and Nod2+/+ mice from faeces collected at different time points: (i) at 4 weeks of age (at weaning, before the housing conditions were established); (ii) 8 weeks of age (before TNBS-colitis induction), and (iii) at day 3 after TNBS colitis induction. We compared the gut microbial profiles in both cohousing and no-cohousing conditions and after colitis induction by TNBS, through the pyrosequencing of the V3-V5 hypervariable region of 16S rRNA gene. The taxonomic distribution in the Nod2-/- and Nod2+/+ mice showed variations in gut microbiota composition in the different experimental time points. Microbial profiles correlated with cytokines production and CD4+LAP+ cells induction and severity of colitis.

为评估Nod2基因型与环境因素（如肠道菌群组成）对此前观测到的实验性结肠炎应答的影响，我们针对不同时间点采集的粪便样本，对Nod2基因敲除（Nod2-/-）与野生型（Nod2+/+）小鼠的肠道菌群开展了宏分类学分析（meta-taxonomic analysis）：(i) 4周龄时（断奶阶段，饲养条件尚未确立前）；(ii) 8周龄时（三硝基苯磺酸[TNBS]结肠炎造模前）；(iii) TNBS结肠炎造模后第3天。我们通过对16S rRNA基因（16S rRNA gene）的V3-V5高变区（V3-V5 hypervariable region）进行焦磷酸测序（pyrosequencing），比较了同笼饲养与非同笼饲养条件下，以及TNBS结肠炎造模前后的肠道微生物群落特征。Nod2-/-与Nod2+/+小鼠的菌群分类分布结果显示，不同实验时间点的肠道菌群组成存在显著差异。微生物群落特征与细胞因子产生、CD4+LAP+细胞诱导以及结肠炎严重程度密切相关。