Project 4 Alteration of Mouse Maternal Gut Microbiota Alters Metabolic Profiles and Immune Phenotype in Offspring

在我们最初的P01中，我们发现口服来自狗之家的灰尘的小鼠对 与补充没有宠物的家庭粉尘的小鼠相比，诱发过敏性肺部炎症。 对添加狗舍尘小鼠的盲肠毒素进行检测，鉴定出一种关键物种--乳杆菌 约翰松二世。口服补充存活但未灭活的约翰逊乳杆菌可降低小鼠对诱导的敏感性 过敏性和呼吸道合胞病毒(RSV)引起的肺部炎症。肺部的这些减少 炎症似乎与骨髓来源的树突状细胞功能活性的改变有关。 (DC)。初步数据表明，补充动物血液循环中的微生物代谢物不同。 不同于那些未补充的动物。有限的数据表明，循环代谢产物的差异 是DC功能改变的原因。我们纳入RSV研究的理由是流行病学 研究表明，人类婴儿感染RSV会增加随后患哮喘的风险。我们的老鼠 模型反映了这种关系，因为新生儿感染RSV导致更大的病理当小鼠 4周后对变应原致敏。有趣的是，我们的初步研究表明，补充 交配前携带约翰逊乳杆菌的雌性小鼠减少后代对过敏原和RSV挑战的反应 与在直接补充的小鼠中观察到的水平相似。在这一观察提出的问题中 母体补充剂对后代的影响是发生在子宫内发育期间还是 产后由母乳成分制成的。这个问题导致了交叉培养实验。在这些 实验用添加或不添加的小鼠的后代分别用添加的或不添加的饲料喂养。 补充的母亲透露母乳喂养可以部分保护没有补充的母亲的幼崽 来自RSV。基于我们的发现，我们在这个项目中提出的研究是基于这样的假设： 微生物区系通过改变新生儿免疫平衡机制来形成发育中的新生儿免疫平衡机制 导致免疫应答差异的子代肠道微生物区系和相关微生物代谢物 以及致病性过敏反应的风险。不过，我们的研究将继续研究这些机制。 哪些微生物变化会影响对过敏原和RSV的病理反应。这些研究将包括进一步的 研究区分子宫内效应和母乳对后代的影响。最后，我们将检查这些影响 补充项目3中选定的细菌群对后代对变应原和 RSV挑战。这些研究将为项目中的人体研究结果提供更好的洞察力 1和2，特别是关于何时可以最安全地采取有效干预措施的问题。

In our initial P01, we found that mice orally supplemented with dust from homes with dogs were resistant to induction of allergic lung inflammation compared to mice supplemented with dust from homes without pets. Examination of ceca from mice supplemented dog-home dust identified a keystone species, Lactobacillus johnsonii. Oral supplementation of mice with viable but not killed L. johnsonii reduced susceptibility to induction of both allergic and respiratory syncytial virus (RSV) induced lung inflammation. These reductions in lung inflammation appear to be related to alterations in the functional activity of bone marrow-derived dendritic cells (DC). Preliminary data suggests that microbial metabolites in the circulation of supplemented animals differ from those of un-supplemented animals. Limited data suggests that the differences in circulating metabolites are responsible for the alterations in DC function. Our rationale for including studies of RSV are epidemiologic studies showing that RSV infections in human infants increase the risk of subsequent asthma. Our mouse models mirror this relationship since neonatal infection with RSV leads to greater pathology when the mice are sensitized to allergen 4 weeks later. Interestingly our preliminary studies have shown that supplementation of female mice with L. johnsonii prior to mating reduces responses to allergen and RSV challenges in offspring to a level similar to that observed in directly supplemented mice. Among the questions raised by this observation was whether the effects of maternal supplementation on offspring occurred during in utero development or post-partum from components of breast milk. This question led to cross-fostering experiments. In these experiments offspring of supplemented or un-supplemented mice were nursed by either supplemented or un- supplemented mothers revealing that breast feeding can partially protect pups of un-supplemented mothers from RSV. Based on our findings we propose studies in this Project based on the hypothesis that the maternal microbiota shapes the developing neonatal immune homeostatic mechanisms through alteration of the offspring gut microbiota and related microbial metabolites which lead to differences in immune responsiveness and the risk of pathogenic allergic responses. Our studies will continue to examine the mechanisms though which microbial changes affect pathologic responses to allergens and RSV. These studies will include further studies to differentiate in utero effects and breast milk effects on offspring. Finally, we will examine the effects of supplementation with consortia of bacteria selected in Project 3 on the response of offspring to allergen and RSV challenges. These studies will provide greater insight into the findings from the human studies in Projects 1 & 2, especially questions concerning when effective interventions might be most safely instituted.