Microbiomal Mediators of TL1A-induced-Fibrosis

摘要 炎症性肠病(IBD)是易感性和易感性之间一系列复杂相互作用的结果。 严重程度基因、环境和粘膜免疫系统，表现为临床疾病。胆量 微生物群与IBD有关；肠道微生物组成已被证明在肠道中发生改变 炎症，但很少有研究研究肠道纤维化。大量潜在的遗传、表观遗传 微生物变量对IBD表型的严重程度也有影响。其中，相对清晰的，临床上- 可识别的表型是那些具有明显的、严重的、纤维性克罗恩病表现的表型。这个 肿瘤坏死因子超家族成员15和肿瘤坏死因子的基因/蛋白组合 类(TL)细胞因子1A(简称：TNFSF15/TL1A)影响炎症和纤维化的严重程度 动物模型和人类疾病。我最近发表的研究结果表明，肠道微生物群与 肠纤维化，以及TL1a发挥其促纤维化作用所依赖的。精确的机械装置和 然而，肠道纤维化的特定微生物因素尚未阐明。因为成纤维细胞是 纤维化的主要细胞类型，TL1a和微生物区系驱动肠道的机制 正如我的初步数据显示的那样，纤维化可能涉及直接诱导成纤维细胞激活。我假设 TNFSF15/TL1A通过改变微生物组在纤维化的诱导和放大中发挥中心作用 增强促纤维化微生物种群并通过直接激活成纤维细胞表达 纤维化相关因素和/或变得更容易受到微生物刺激的影响。在目标1中，我将确定 无论是TL1A诱导的小鼠模型纤维化，还是患有克罗恩病的退伍军人中TNFSF15的遗传风险 与微生物群的变化有关。我将用16S rRNA对肠道微生物组进行鉴定 具有和不具有TNFSF15遗传风险的患者的粪便和组织样本的测序。要确认 这些相关生物、WT和TL1A转基因无菌C57/BL6小鼠的因果效应将是 与候选细菌联合定植以评估体内纤维化的发展。这些微生物区系 也将使用代谢组学方法来表征它们，以便更具体地了解它们在疾病中的作用 发病机制。在目标2中，我将描述DIRECT的TL1a反应效应和分子机制 利用原代分离的成纤维细胞在体外成纤维细胞上鉴定AIM 1中鉴定的细菌产物和代谢物。在……里面 目的3，我将确定特定的细菌代谢产物是否可以在体内引起肠道纤维化。 转基因小鼠模型中的选择性给药。这项拟议研究的结果将提供对 与TL1A共同推动肠道纤维化的特定微生物或其产物。如果寄主-微生物组 通过操纵TL1a或TL1a可以减轻相互作用和由此导致的促纤维化成纤维细胞表型 微生物组/代谢组，在遗传易感个体中，肠纤维化可以先发制人。这些 因此，研究可能会揭示更多的下游途径、分子和潜在的治疗靶点。

ABSTRACT Inflammatory Bowel Disease (IBD) results from a series of complex interactions between susceptibility and severity genes, the environment and the mucosal immune system, presenting as clinical disease. The gut microbiome contributes to IBD; altered gut microbial composition has been demonstrated in intestinal inflammation, but few studies have examined intestinal fibrosis. A vast number of potential genetic, epigenetic and microbiotic variables contribute to the severity of IBD phenotypes. Among these, relatively clear, clinically- identifiable phenotypes are those with a distinct, severe, fibrosing Crohn’s disease presentation. The gene/protein combination of tumor necrosis factor superfamily (TNFSF) member 15 and tumor necrosis factor- like (TL) cytokine 1A (referred to as: TNFSF15/TL1A) influences the severity of inflammation and fibrosis in both animal models and human disease. My recently published findings have implicated the gut microbiome in intestinal fibrosis, and on which TL1A depends to exert its pro-fibrotic effects. The precise mechanisms and specific microbial contributors to intestinal fibrosis have yet to be elucidated, however. As fibroblasts are a predominant cell type responsible for fibrosis, the mechanisms by which TL1A and microbiota drive intestinal fibrosis likely involve direct induction of fibroblast activation, as my preliminary data demonstrates. I hypothesize that TNFSF15/TL1A plays a central role in the induction and amplification of fibrosis by altering the microbiome to enhance fibrosis-promoting microbial populations and through the direct activation of fibroblasts to express fibrosis-related factors and/or to become more susceptible to microbial stimulation. In Aim 1, I will determine whether TL1A-induced fibrosis in mouse models or TNFSF15-genetic risk in Veterans with Crohn’s disease is associated with alterations in the microbiome. I will characterize the gut microbiome as assessed by 16S rRNA sequencing of stool and tissue specimens from patients with and without TNFSF15-genetic risk. To confirm the causal efficacy of these correlated organisms, WT and TL1A-transgenic germ-free C57/BL6 mice will be colonized with the candidate bacterial consortia to evaluate for development of fibrosis in vivo. These microbiota will also be characterized using metabolomic methods to allow more specific insight into their role in disease pathogenesis. In Aim 2, I will characterize the TL1A-responsive effects and molecular mechanisms of direct bacterial products and metabolites identified in Aim 1 on fibroblasts using primary isolated fibroblasts in vitro. In Aim 3, I will determine if specific bacterial metabolites can causally mediate intestinal fibrosis in vivo using selective administration in engineered mouse models. The results of this proposed study will provide insight into the specific microbes, or their products, that drive intestinal fibrosis in concert with TL1A. If host-microbiome interactions and resulting pro-fibrotic fibroblast phenotypes can be mitigated by manipulation of TL1A or the microbiome/metabolome, intestinal fibrosis may be pre-empted in genetically susceptible individuals. These investigations may thus reveal additional downstream pathways, molecules, and potential targets for therapy.