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

肠道微生物群在预防肠道血清型伤寒沙门氏菌（S. Tm）感染中起关键作用。在小鼠中，用抗生素链霉素治疗会短暂地破坏微生物群，使S. Tm在肠道定植、组织入侵和诱导肠道炎症。除了微生物群外，粘膜屏障对s.m m的即时免疫防御也有重要作用。到目前为止，人们对微生物群和先天免疫系统的相互作用知之甚少。我们分析了具有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+/-同窝对照相比，AGR2-/-小鼠对S. Tm诱导的肠道炎症有保护作用。在链霉素的作用下，AGR2-/-小鼠表现出微生物群组成的改变和微生物群密度的增加。因此，我们假设AGR2-/-小鼠的粘膜稳态失衡诱导了微生物群的改变，从而增加了对S. Tm感染的抵抗力。在我们的病例中，肠道微生物群可以弥补粘膜屏障的缺陷。在这一建议中，我们旨在进一步表征改变的粘膜稳态对肠道微生物群的影响，以及这如何与对沙门氏菌感染的抵抗力增加有关。为了分析粘膜稳态和微生物群对链球菌感染结果的影响，我们的目标是产生与特定肠道微生物群相关的无菌和非细菌AGR2-/-小鼠。为此，我们将应用我们实验室开发的新型“Oligo-Mouse-Microbiota”。

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.