The role of IL-1?-inducing pathobionts in the pathogenesis of Crohn?s disease

项目摘要/摘要： 克罗恩病(CD)是一种慢性胃肠道炎症性疾病，影响70万人 在美国的人们。白介素1β是一种重要的促炎介质，被认为是 与CD的肠炎症相关，因为IL-1β在CD的肠粘膜中的表达升高 CD患者。同样，NLRP3的遗传变异，炎症体蛋白在 IL-1β的产生与CD的风险增加有关。此外，Atg16l1基因缺陷小鼠，以及 自噬基因与CD连锁，表现为增加依赖NLRP3的IL-1β的产生和对结肠炎的敏感性。 因此，IL-1β似乎对CD有贡献，但CD中诱导IL-1β的机制以及IL-1β如何 促进CD的发病机制尚不清楚。鉴于我们最近的发现，肠道微生物区系对 诱导黏膜IL-1β，本研究的长期目标是揭示肠道微生物区系如何 可能通过诱导IL-1β参与CD的发病机制。为此，我们已经产生了 一种人源化GnotoBiotic小鼠(HGB)模型，其中无菌(GF)小鼠与人类(健康)共同定居 个人和CD患者)微生物。利用这一模型，我们发现GF小鼠的定植通过 CD微生物可诱导结肠粘膜中包括IL-1β在内的促炎因子显著升高， 而健康的微生物并没有引起这些反应。令人惊讶的是，CD的殖民，但不健康， 在两种不同的小鼠结肠炎模型(硫酸葡聚糖)中，微生物导致严重结肠炎的发生 钠诱导的结肠炎和生长因子IL-10缺乏的小鼠(人类微生物群定居)。IL-1β的诱导 这是镉微生物群产肠能力所必需的。此外，我们已经确定了IL-1β的候选者- 诱导病原体，选择性地积聚在CD患者体内。根据这些结果，我们的中央 假说认为CD患者体内IL-1β诱导的致病因子丰富，从而导致CD的发生 和/或肠炎的进展。具体目标是：1.澄清CD-1的机制 相关的致病因子激活了炎症体。我们将确定哪些CD关联以及如何关联 病原体激活了炎症体。2.识别CD相关免疫途径 病毒肽诱导的IL-1β。我们将分析CD-1诱导的IL-1β下游T细胞反应。 相关的病态生物。3.确定Cd相关致病基因诱导IL-1β的机制 会导致结肠炎。我们将确定CD选择性成员诱导IL-1β的机制。 相关的致病因素会导致结肠炎的发生。因此，拟议的研究将阐明这种联系。 肠道微生物区系诱导的IL-1β与CD发病机制的关系

Project Summary/Abstract: Crohn's disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract that affects 0.7 million people in the United States. Interleukin (IL)-1β is an important pro-inflammatory mediator that is believed to be associated with intestinal inflammation in CD, as the IL-1β expression is elevated in the intestinal mucosa of patients with CD. Likewise, genetic variation in NLRP3, the inflammasome protein which plays a pivotal role in the production of IL-1β, is associated with increased risk for CD. Furthermore, mice deficient in Atg16l1, an autophagy gene linked to CD, display increased NLRP3-dependent IL-1β production and sensitivity to colitis. Thus, IL-1β appears to contribute to CD, yet the mechanisms by which IL-1β is induced in CD and how IL-1β promotes CD pathogenesis remain uncertain. Given our recent findings that the gut microbiota is essential for the induction of mucosal IL-1β, the long-term objective of this study is to unravel how the gut microbiota contributes to disease pathogenesis in CD likely through the induction of IL-1β. To this end, we have generated a humanized gnotobiotic mouse (hGB) model, in which germ-free (GF) mice are colonized with human (healthy individuals and CD patients) microbiotas. Utilizing this model, we have found that GF mice colonization by the CD microbiotas induces a marked elevation of pro-inflammatory factors, including IL-1β, in colonic mucosa, while healthy microbiotas did not elicit these responses. Strikingly, colonization of CD, but not healthy, microbiotas led to the development of severe colitis in two different mouse models of colitis (dextran sulfate sodium-induced colitis and GF IL-10-deficient mice colonized with human microbiotas). Induction of IL-1β is required for the colitogenic capacity of the CD microbiota. Furthermore, We have identified candidates of IL-1β- inducing pathobionts, which selectively accumulated in CD patients. Based on these results, our central hypothesis is that IL-1β-inducing pathobionts are enriched in CD patients, which leads to the development and/or progression of intestinal inflammation. Specific aims are: 1. Clarify the mechanism by which CD- associated pathobionts activate the inflammasome. We will identify which and how the CD-associated pathobionts activate the inflammasome. 2. Identify the immune pathways elicited by CD-associated pathobiont-induced IL-1β. We will analyze the T cell responses downstream of IL-1β that are induced by CD- associated pathobionts. 3. Determine the mechanism by which CD-associated pathobiont-induced IL-1β leads to colitis. We will determine the mechanisms by which IL-1β induced by selective members of CD- associated pathobionts leads to the development of colitis. Thus, the proposed study will shed light on the link between the microbiota-induced IL-1β in the intestine and the pathogenesis of CD.