Autophagy and Nod2 Function in Crohn's Disease

克罗恩病中的自噬和 Nod2 功能

• 批准号: 7845615
• 负责人: CHRISTINE L MCDONALD
• 金额: $ 38.86万
• 依托单位: CLEVELAND CLINIC LERNER COM-CWRU
• 依托单位国家: 美国
• 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
• 来源: https://reporter.nih.gov/project-details/7845615
• 关键词: Acetylmuramyl-Alanyl-Isoglutamine; Anti-Bacterial Agents; Autophagocytosis; Bacteria; Binding; Cell Line; Cell Survival; Cell Wall; Cells; Chronic; Crohn' s disease; Data; Defect; Development; Disease; Disease susceptibility; Eating; Environmental Risk Factor; Etiology; Family; Figs - dietary; Genes; Genetic; Guanosine Triphosphate Phosphohydrolases; Immune; Immune response; Immune system; Immunity; Impairment; Individual; Inflammation Mediators; Inflammatory; Inflammatory Bowel Diseases; Lead; Link; Lysosomes; Modeling; Mutate; Mutation; Nucleotides; Nutrient; Organelles; Pathogenesis; Pathway interactions; Patients; Phagocytes; Play; Process; Production; Proteins; Recycling; Role; Signal Pathway; Signal Transduction; Starvation; Susceptibility Gene; Testing; Vacuole; antimicrobial; design; genome wide association study; microbial; novel; public health relevance; response; sensor

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: Recent advances in the genetics of Crohn's disease (CD) indicate that alterations in an immune pathway rather than a single gene may be important in CD pathogenesis. We propose to study the interactions of three genes associated with CD susceptibility and define if they are a part of the same innate immune system pathway. The results of our proposed studies may benefit individuals with CD by identifying a crucial process altered in the disease, leading to the design and use of more specific therapies targeting this pathway.

描述（由申请人提供）：克罗恩病（CD）是一种慢性且令人衰弱的炎症性肠病，病因未知；但是，很明显，其发展所需的遗传成分以及环境因素。最近在理解CD的遗传学方面已取得了巨大进步。尽管几个染色体基因座与IBD易感性有关，但直到去年，只有一个基因被最终被鉴定为CD易感基因。该基因是NOD2（核苷酸结合，寡聚结构域2），它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鉴定出多个新型CD易感基因。这些新的CD敏感性基因中的许多也调节免疫反应，表明免疫途径的失调而不是单个基因可能在CD发病机理中很重要。这些过程之一是自噬。自噬（实际上是“自我进食”）是响应饥饿的细胞存活机制，其中细胞器被分解并回收以提供营养。这种机制在通过先天免疫系统清除细胞内细菌中也起着至关重要的作用。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。这些微生物传感器之一是NOD2，它检测到称为Muramyl二肽（MDP）的细菌细胞壁的特定成分。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激活NOD2。这些结果提供了在CD中突变的两种单独的分子之间的联系，并导致我们提出以下中心假设：自噬基因中的CD相关突变，ATG16L1（自噬相关16类蛋白1）和IRGM（IRGM）和IRGM（免疫相关的GTPase家族，M），以及NOD2损害了与Indate Insune patherate Pathere pathere pathere patherate pathere pathere pathere pathere and Impair and Impair。我们以两种非排他性的方式将自噬和NOD2合作假设：（1）MDP刺激NOD2激活自噬是必不可少的抗微生物反应，并且（2）自噬参与MDP内在化和NOD2激活。 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.我们提出的研究的结果可以通过确定CD中发生的关键过程来使CD的个体受益，从而导致针对该途径的更具体的CD疗法的设计和使用。公共卫生相关性：克罗恩病（CD）的遗传学的最新进展表明，免疫途径而不是单个基因的改变可能在CD发病机理中很重要。我们建议研究与CD敏感性相关的三个基因的相互作用，并定义它们是否是同一先天免疫系统途径的一部分。我们提出的研究的结果可以通过确定疾病中的关键过程来使CD患者受益，从而导致针对该途径的更具体的疗法的设计和使用。