Generation of gnotobiotic mice to investigate the role of the intestinal microbiota in Salmonella enterica spp. I serovar Typhimurium colitis in AGR2-deficient mice

肠道微生物区系在预防肠道沙门氏菌群伤寒沙门氏菌(S.TM)感染中起着关键作用。在小鼠中，用抗生素链霉素治疗会暂时扰乱微生物区系，使S.TM能够在肠道内定植，组织侵袭，并诱导肠道炎症。除微生物区系外，粘膜屏障还可显著促进对S.TM的即时免疫隔离。到目前为止，人们对微生物区系和先天免疫系统的相互作用还知之甚少。我们分析了存在严重粘膜屏障缺陷的前梯度2(AGR2)缺陷小鼠的S.TM感染情况。然而，与我们的预测相反，与AGR2+/-对照相比，AGR2-/-小鼠对S.TM诱导的肠道炎症具有保护作用。AGR2-/-小鼠对链霉素的反应表现出微生物区系组成的改变和微生物区系密度的增加。因此，我们假设AGR2-/-小鼠粘膜内环境失衡导致微生物区系改变，从而增加了对S.TM感染的抵抗力。在我们的案例中，肠道微生物群可以弥补粘膜屏障的缺陷。在这项建议中，我们的目标是进一步描述粘膜稳态改变对肠道微生物区系的影响，以及这与增加对S.TM感染的抵抗力之间的关系。为了剖析粘膜动态平衡和微生物区系对S.TM感染结局的影响，我们的目标是产生与特定肠道微生物区系相关的无菌和诺生菌AGR2-/-小鼠。为此，我们将应用我们实验室开发的一种新颖的“寡鼠-微生物区系”。

The intestinal microbiota plays a pivotal role in protection against the enteric Salmonella serovar Typhi-murium (S. Tm) infection. In mice, treatment with the antibiotic streptomycin transiently disrupts the microbiota and enables S. Tm colonization of the gut, tissue invasion and induction of intestinal inflam-mation. Besides the microbiota, the mucosal barrier significantly contributes to immediate immune de-fence against S. Tm. So far, the interplay of the microbiota and the innate immune system is poorly un-derstood. We analyzed S. Tm infection in mice deficient in anterior gradient 2 (AGR2), which have se-vere mucosal barrier defects. Yet, in opposition to our prediction, AGR2-/- mice were protected against S. Tm induced gut inflammation, in contrast to AGR2+/- littermate controls. AGR2-/- mice exhibited altered microbiota composition and increased microbiota density in response to streptomycin. Thus, we hypothe-size that imbalanced mucosal homeostasis in AGR2-/- mice induced microbiota alterations which provided increased resistance against S. Tm infection. In our case, the intestinal microbiota could compensate for mucosal barrier defects. In this proposal we aim at further characterizing the influence of altered mucosal homeostasis on the intestinal microbiota and how this is related to increased resistance against S. Tm in-fection. To dissect the effect of mucosal homeostasis and the microbiota on the outcome of S. Tm infec-tion, we aim to generate germfree and gnotobiotic AGR2-/- mice associated with a defined gut microbiota. To this end, we will apply a novel “Oligo-Mouse-Microbiota” developed in our laboratory.