Autophagy and Nod2 Function in Crohn's Disease

克罗恩病中的自噬和 Nod2 功能

基本信息

批准号：
8587008
负责人：
CHRISTINE L MCDONALD
金额：
$ 0.1万
依托单位：
CLEVELAND CLINIC LERNER COM-CWRU
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-07-01 至 2014-04-30
项目状态：
已结题

项目摘要

Crohn's disease (CD) is a chronic and debilitating inflammatory bowel disease with unknown etiology; however, it is clear that there are both genetic components as well as environmental factors that are required for its development. Tremendous advances have been made recently in understanding the genetics of CD. Although several chromosomal loci have been associated with IBD susceptibility, until last year, only one gene had been conclusively identified as a CD susceptibility gene. This gene is NOD2 (nucleotide-binding, oligomerization domain 2), which encodes an intracellular sensor of bacteria in the innate immune system. Recent genome-wide association scans have identified multiple, novel CD susceptibility genes. Many of these new CD susceptibility genes also modulate immune responses, suggesting that dysregulation of an immune pathway rather than a single gene may be important in CD pathogenesis. One of these processes is autophagy. Autophagy (literally "self-eating") is best known as a cell survival mechanism in response to starvation, where organelles are broken down and recycled to provide nutrients. This mechanism also plays a crucial role in the clearance of intracellular bacteria by the innate immune system. Bacteria and bacterial components induce autophagy, linking innate immune microbial sensors to autophagy. One of these microbial sensors is Nod2, which detects a specific component of the bacterial cell wall called muramyl dipeptide (MDP). Our preliminary data demonstrates that stimulation of cells with MDP not only activates autophagy, but suggests autophagy may also be involved in activation of Nod2 by MDP. These results provide a link between two separate classes of molecules mutated in CD and lead us to propose the following central hypothesis: CD- associated mutations in the autophagy genes, ATG16L1 (autophagy related 16-like protein 1) and IRGM (immunity-related GTPase family, M), and NOD2 impair the same critical innate immune pathway and impairment of this pathway contributes to CD pathogenesis. We hypothesize autophagy and Nod2 function together in two non-exclusive ways: (1) MDP stimulation of Nod2 activates autophagy as an essential anti-microbial response, and (2) autophagy is involved in MDP internalization and Nod2 activation. This hypothesis will be tested by the following three specific aims using both primary cells and cell lines: 1) Determine the role of Nod2 in activation of autophagy - is autophagy a component of Nod2 stimulated anti- microbial responses?, 2) Characterize the mechanism of MDP internalization - is it autophagy?, 3) Analyze alterations in autophagy in phagocytic cells of CD patients. The results of our proposed studies may benefit individuals with CD by identifying a crucial processes altered in CD, leading to the design and use of more specific CD therapies targeting this pathway.

克罗恩病 (CD) 是一种慢性且令人衰弱的炎症性肠病，病因不明。然而，很明显，其形成既需要遗传因素，也需要环境因素。发展。最近在了解 CD 遗传学方面取得了巨大进展。尽管多个染色体位点与 IBD 易感性相关，但直到去年，只有一个基因已被最终鉴定为 CD 易感基因。该基因是 NOD2（核苷酸结合，寡聚结构域 2)，编码先天免疫系统中细菌的细胞内传感器。最近的全基因组关联扫描已经鉴定出多个新型 CD 易感基因。其中许多新的CD易感基因也调节免疫反应，这表明免疫调节失调在 CD 发病机制中，可能重要的是信号通路而不是单个基因。这些过程之一是自噬。自噬（字面意思是“自食”）是最有名的细胞生存机制，以响应饥饿，细胞器被分解并回收以提供营养。这个机制还起到了在先天免疫系统清除细胞内细菌方面发挥着至关重要的作用。细菌和细菌成分诱导自噬，将先天免疫微生物传感器与自噬联系起来。这些微生物之一传感器是Nod2，它检测细菌细胞壁的一种特定成分，称为胞壁酰二肽（MDP）。我们的初步数据表明，用 MDP 刺激细胞不仅激活自噬，而且表明自噬也可能参与 MDP 对 Nod2 的激活。这些结果提供了之间的联系 CD 中发生突变的两类不同分子，使我们提出以下中心假设：CD- 自噬基因 ATG16L1（自噬相关 16 样蛋白 1）和 IRGM 的相关突变（免疫相关 GTP 酶家族，M）和 NOD2 损害相同的关键先天免疫途径，并且该途径的损伤导致 CD 发病机制。我们假设自噬和Nod2 以两种非排他性的方式共同发挥作用：(1) MDP 刺激 Nod2 激活自噬作为必需的 (2)自噬参与 MDP 内化和 Nod2 激活。这将使用原代细胞和细胞系通过以下三个具体目标来检验假设：1) 确定 Nod2 在自噬激活中的作用 - 自噬是 Nod2 刺激的抗-自噬的一个组成部分微生物反应？, 2) 描述 MDP 内化机制 - 是自噬吗？, 3) 分析 CD患者吞噬细胞自噬的改变。我们提出的研究结果可能会受益患有 CD 的个体通过识别 CD 中改变的关键流程，导致设计和使用更多针对该途径的特定 CD 疗法。