Defining the role of Nod2 and bacteria in Atg16L1-dependent intestinal disease.

描述(由申请人提供)：我们的长期目标是了解遗传易感性和环境因素是如何结合在一起来调节炎症性肠病的。Atg16L1和NOD2是两个克罗恩病的易感基因，因其在细菌天然免疫防御中的重要作用而备受关注。虽然Atg16L1在自噬和NOD2在细菌识别中的重要作用已经被证明，但现在很明显，这些分子的突变在细胞和整个生物体水平上都会产生复杂和意想不到的后果。因此，我们在肠道疾病的背景下检查这些易感基因，以解释最近揭示新的下游功能和途径的研究，这是至关重要的。我们先前证明了Atg16L1突变小鼠(Atg16L1HM)在感染小鼠诺如病毒MNV时会出现肠道异常。这些异常包括当感染MNV的Atg16L1HM小鼠被化学物质DSS损伤时产生类似克罗恩的病理。值得注意的是，我们现在发现这些病理的发展取决于共生细菌和NOD2。当Atg16L1HM小鼠接受抗生素治疗或与NOD2基因敲除小鼠杂交时，它们可以免受MNV和DSS治疗引起的肠道疾病的影响。鉴于目前该领域在定义NOD2功能方面的挑战以及人们对了解共生细菌的极大兴趣，我们将利用这些观察结果来深入了解粘膜免疫和克罗恩病的发病机制。在这项提议中，我们将测试一个模型，在该模型中，NOD2感应特定的肠道细菌来介导Atg16L1HM小鼠的炎症。我们还将确定与克罗恩病相关的NOD2移码突变(Nod2f)是否与存在Atg16L1突变的NOD2缺失相似或不同，因为这一信息将对炎症性疾病中的基因-基因相互作用具有重要意义。我们将以以下具体目标来解决这些问题：(1)确定导致Atg16L1HM小鼠克罗恩样病理的NOD2信号通路，(2)确定Atg16L1HM小鼠疾病所需的特定细菌种群，以及(3)比较NOD2缺失和Nod2fs表达在肠道炎症中的作用。我们有一个独特的机会来表征两个非常感兴趣的易感基因，以及在一个多次打击的疾病模型中的共生细菌菌群，该模型重建了类似于在患者中观察到的病理。

DESCRIPTION (provided by applicant): Our long-term goal is to understand how genetic susceptibility and environmental factors combine to mediate inflammatory bowel disease. Atg16L1 and Nod2 are two Crohn's disease susceptibility genes that have received much attention because of their critical function in innate immune defense against bacteria. While an essential role for Atg16L1 in autophagy and Nod2 in bacterial recognition have been demonstrated, it is now clear that mutating these molecules have complex and unanticipated consequences at both the cellular and whole organism level. Therefore, it is critical that we examine these susceptibility genes in the context of intestinal disease to interpret the recent studies that are revealing new downstream functions and pathways. We previously demonstrated that Atg16L1 mutant mice (Atg16L1HM) develop intestinal abnormalities when infected with the mouse norovirus MNV. These abnormalities include the generation of Crohn's-like pathologies when MNV-infected Atg16L1HM mice are injured with the chemical DSS. Remarkably, we have now found that development of these pathologies depends on both commensal bacteria and Nod2. When Atg16L1HM mice are treated with antibiotics or crosed to Nod2 knockout mice, they are protected from intestinal disease induced by MNV and DSS treatment. Given the current challenge in the field in defining Nod2 function and the great interest in understanding commensal bacteria, we will take advantage of these observations to gain insight into mucosal immunity and Crohn's disease pathogenesis. In this proposal, we will test a model in which Nod2 senses specific intestinal bacteria to mediate inflammation in Atg16L1HM mice. We will also determine if the Nod2 frameshift mutation (Nod2fs) associated with Crohn's disease is similar or distinct to Nod2 deletion in the presence of Atg16L1 mutation since this information will have important implications for gene-gene interactions in inflammatory diseases. We will address these issues with the following specific aims: (1) Identify the Nod2 signaling pathway that is responsible for Crohn's-like pathologies in Atg16L1HM mice, (2) Define the specific bacterial population required for disease in Atg16L1HM mice, and (3) Compare the effect of Nod2 deletion and Nod2fs expression in intestinal inflammation. We have a unique opportunity to characterize two susceptibility genes of great interest and the commensal bacterial flora in a multi-hit disease model that recreates pathologies similar to those observed in patients.