Regulation of the intestinal colonization niche by epithelial cell death

项目摘要 肠道微生物组由栖息在胃肠道中的数万亿微生物组成。 由微生物组产生的代谢物到达肠外组织，并且可以在血液中发现， 因此能够影响身体的几乎所有组织。有趣的是，一些基因的表达 胃肠道的功能取决于微生物组的定植。在这个项目中，我们将探索 肠道微生物组控制肠上皮细胞（IEC）基因调控的机制， 通过研究参与IEC细胞死亡的微生物组调节基因。肠道沙门氏菌伤寒血清变型 鼠伤寒（STm）是一种善于克服宿主防御以引起疾病的病原体。STM 通过利用宿主反应引发有利于病原体生长的炎症反应 感染我们的初步研究结果表明，STm能够从稳态微生物组中获益- 介导的细胞死亡途径尚未被描述。在稳态条件下，产生的代谢物 由微生物组引起的肠上皮细胞的焦亡，这有助于维持正常的上皮更新。可是 STm感染时，病原体利用这一途径引起IEC焦亡增加，导致STm增加 胃肠道中的数字。我们的早期结果表明，IEC焦亡途径的组成部分的损失 导致较低的STm管腔生长和传播到肠外器官，然而，目前还不清楚STm如何 激活IEC焦亡，以及该途径是否确实导致肠上皮细胞焦亡增加， 感染时的上皮细胞。因此，我假设在胃肠道感染期间，STm 这是微生物组控制的稳态IEC特异性细胞死亡途径的优势，以大量繁殖。 为了阐明微生物组和STm如何激活IEC焦亡，以及这种激活如何导致 细胞死亡和下游病原体在胃肠道内和肠外部位的扩张， 我们提出两个具体目标。在AIM 1中，我们将评估肠道微生物组对诱导IEC的贡献。 焦亡，通过使用测序和体内小鼠模型的组合，使用常规和gnotobiotic 小鼠在AIM 2中，我们将使用小鼠感染模型来确定STm如何在感染期间引起IEC焦亡， 并定义上游激活途径。我们的机械方法将提供一个因果关系之间的联系 微生物组、宿主细胞死亡途径和病原体扩张。成功完成此提案将 确定了一个以前未定义的IEC细胞死亡途径，该途径在稳态和感染性条件下起着至关重要的作用。 条件这个项目还将扩大我的培训，包括IEC生物学的关键方法和概念 以及微生物组的研究。总之，拟议的研究和培训计划将有助于更好地 了解IEC及其在宿主免疫中的作用，同时为我未来的独立职业生涯做好准备。 宿主-微生物相互作用领域的研究者。

Project Summary The intestinal microbiome is made up of trillions of microorganisms that inhabit the gastrointestinal tract. Metabolites produced by the microbiome reach extraintestinal tissues, and can be found in the bloodstream, and are thereby able to influence almost all tissues of the body. Interestingly, the expression of a number of genes of the gastrointestinal tract is dependent on colonization by the microbiome. In this project, we will explore the mechanisms through which the gut microbiome controls gene regulation of intestinal epithelial cells (IECs), through the study of a microbiome-modulated gene involved in IEC cell death. Salmonella enterica serovar Typhimurium (STm) is a pathogen that is adept at overcoming host defenses in order to cause disease. STm triggers an inflammatory response that benefits growth of the pathogen by taking advantage of the host response to infection. Our preliminary findings suggest that STm is able to benefit from a homeostatic microbiome- mediated cell death pathway that has yet to be described. Under steady state conditions, metabolites produced by the microbiome lead to pyroptosis of IECs, which helps maintain normal epithelial turnover. However, upon STm infection, the pathogen harnesses this pathway to elicit increased IEC pyroptosis, leading to increased STm numbers in the gastrointestinal tract. Our early results indicate loss of components of the IEC pyroptosis pathway led to lower STm luminal outgrowth and dissemination to extraintestinal organs, yet, it is unclear how STm activates IEC pyroptosis, and whether this pathway indeed leads to an increase in pyroptosis of intestinal epithelial cells during infection. Thus, I hypothesize that during infection of the gastrointestinal tract, STm takes advantage of a microbiome-controlled homeostatic IEC-specific cell death pathway to bloom to high numbers. In order to elucidate how the microbiome and STm activate IEC pyroptosis, and how this activation leads to cell death and downstream pathogen expansion within the gastrointestinal tract and in extraintestinal sites, we propose two specific aims. In AIM 1 we will assess the contribution of the gut microbiome to induction of IEC pyroptosis, by using a combination of sequencing and in vivo mouse models using conventional and gnotobiotic mice. In AIM 2 we will use mouse infection models to determine how STm elicits IEC pyroptosis during infection, and define the upstream activation pathway. Our mechanistic approach will provide a causal link between the microbiome, a host cell death pathway, and pathogen expansion. Successful completion of this proposal will identify a previously undefined IEC cell death pathway that plays a crucial role under steady state and infectious conditions. This project will additionally expand my training to include key methods and concepts in IEC biology and in the study of the microbiome. Altogether, the research and training plan proposed will facilitate a better understanding of IECs and their role in host immunity, while preparing me for a future career as an independent investigator in the field of host-microbe interactions.