Role of IRGM proteins in immunity to enteric bacteria

IRGM 蛋白在肠道细菌免疫中的作用

• 批准号: 9797779
• 负责人: GREGORY A TAYLOR
• 金额: $ 32.06万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9797779
• 关键词: Address; Affect; Alleles; Apoptotic; Autophagocytosis; Bacteria; Binding Proteins; Biochemical Pathway; Cell Death; Cell Survival; Cell physiology; Cells; Chronic; Citrobacter rodentium; Consequentialism; Crohn' s disease; Data; Defect; Dendritic Cells; Development; Diagnostic; Disease; Disease susceptibility; Enterobacteriaceae; Escherichia coli; Excision; Exhibits; Genes; Genetic; Genetic Polymorphism; Genotype; Goals; Growth; Hematopoietic; Homeostasis; Homologous Gene; Human; Immune; Immune System Diseases; Immune response; Immunity; Impairment; In Vitro; Individual; Inflammation; Inflammatory; Inflammatory Bowel Diseases; Innate Immune Response; Intestines; Knock-out; Knockout Mice; Lamina Propria; Lead; Leukocytes; Link; Lymphoid; Membrane; Metabolic; Metabolism; Microbe; Mitochondria; Modeling; Mus; Myelogenous; Myeloid Cells; Output; Pathogenesis; Pathogenicity; Pathway interactions; Pharmacology; Play; Population; Predisposition; Process; Proteins; Regulation; Resistance; Role; Susceptibility Gene; System; T-Lymphocyte; Testing; Therapeutic; Variant; Vesicle; base; cell type; cohort; disorder risk; glucose metabolism; gut microbiota; immune function; in vivo; macrophage; mortality; mouse model; novel diagnostics; novel therapeutics; protein function; response; risk variant; tool

ABSTRACT IRGM is a gene that regulates autophagy and has been identified as Crohn’s disease susceptibility gene. The proposed studies will define its role in intestinal immunity, which is currently unknown. This will allow a greater understanding of how some individuals acquire Crohn’s disease, as well as identify biochemical pathways that may be targeted for better therapeutics and/or diagnostics. Current dogma suggests that impaired autophagy, through lack of IRGM or other autophagy proteins, undermines intestinal immunity to enteric bacteria by reducing autophagic clearance of those bacteria. However, a distinct hypothesis proposed here is that lack of IRGM or a mouse homologue, Irgm1, leads to decreases in autophagic removal of mitochondria in certain intestinal immune cells. Accumulation of defective mitochondria perturbs cellular homeostasis, particularly in myeloid cells, reducing their ability to drive innate immune responses to enteric bacteria. This will be addressed with the following aims: Aim 1. Determine the immune components regulated by Irgm1 that are required for resistance to pathogenic enteric bacteria. Preliminary studies indicate that resistance to Citrobacter rodentium – a mouse model of adherent invasive Escherichia coli linked to Crohn’s disease – is markedly reduced in mice with a global knock-out of Irgm1. It is not clear which leukocyte populations in the lamina propria are impacted by Irgm1 deficiency. These studies will address the hypothesis that Irgm1 deficiency increases cell death in both macrophages and dendritic cells reducing their availability to drive a robust Th1 response. Conditional Irgm1- deficient mice will be used to identify the primary cell type(s) responsible for Irgm1-dependent susceptibility to C. rodentium and to determine how Irgm1 regulates homeostasis and function of those cells. Aim 2. Determine the mechanism(s) through which Irgm1 modulates myeloid cell function. These studies will address the hypothesis that the impaired autophagy that accompanies Irgm1-deficiency reduces autophagic removal of damaged mitochondria in myeloid cells. The consequential accumulation of damaged mitochondria, as well as the metabolic shifts caused by the damaged mitochondria, increase apoptotic cell death. Comprehensive analyses of macrophages and DC will be performed in vitro and in vivo, using pharmacologic and/or genetic tools to probe autophagy, mitochondrial pathways, metabolism, and cell death. Aim 3. Determine how disease variants of the IRGM gene alter human leukocyte function. The mechanism through which polymorphisms in human IRGM affect immune function and drive Crohn’s disease is unknown. These studies will address the hypothesis that - similar to mouse Irgm1 - perturbations in human IRGM expression alter autophagy, leading to changes in mitophagy and metabolism with downstream impacts on myeloid cell survival and function. This will be tested using leukocytes isolated from individuals carrying the IRGM major allele or disease risk allele, assessing autophagic, mitochondrial, metabolic, and functional outputs.

抽象的 IRGM是调节自噬的基因，并被鉴定为克罗恩病敏感性基因。 拟议的研究将定义其在目前未知的肠道免疫中的作用。这将允许 对某些人如何患上克罗恩病，并识别生化 可能针对更好治疗和/或诊断的途径。 当前的教条表明，由于缺乏IRGM或其他自噬蛋白，自噬受损， 通过降低这些细菌的自噬清除，破坏了肠道免疫进入细菌。然而， 这里提出的一个独特的假设是缺乏IRGM或小鼠同源物IRGM1导致下降 在某些肠道免疫球中自噬去除线粒体。线粒体有缺陷的积累 渗透细胞稳态，尤其是在髓样细胞中，降低了它们驱动先天免疫的能力 进入细菌的反应。这将以以下目的解决： 目标1。确定由IRGM1调节的免疫成分 致病启动子细菌。初步研究表明对柠檬酸啮齿动物的抗性 - 小鼠 与克罗恩病有关的粘附侵入性大肠杆菌模型 - 在全球范围内显着降低 IRGM1的敲除。目前尚不清楚lamina lamina prepriations哪些白细胞受到IRGM1的影响 不足。这些研究将解决以下假设：IRGM1缺乏症会增加两者的细胞死亡 巨噬细胞和树突状细胞降低了其驱动稳健TH1反应的可用性。有条件的IRGM1- 缺乏小鼠将用于识别负责IRGM1依赖性易感性的主要细胞类型 C.啮齿动物并确定IRGM1如何调节这些细胞的稳态和功能。 AIM 2。确定IRGM1调节髓样细胞功能的机制。这些 研究将解决以下假设，即涉及IRGM1缺乏症的自噬受损会降低 自噬去除髓样细胞中受损的线粒体。受损的结果积累 线粒体以及因线粒体受损而引起的代谢转移，增加了凋亡细胞死亡。 对巨噬细胞和直流的全面分析将在体外和体内进行药理。 和/或遗传工具，用于探测自噬，线粒体途径，代谢和细胞死亡。 目标3。确定IRGM基因的疾病变异如何改变人白细胞功能。这 人类IRGM中多态性影响免疫功能和驱动克罗恩病的机制是 未知。这些研究将解决以下假设：与小鼠IRGM1相似 - 人类IRGM的扰动 表达改变自噬，导致线粒体和代谢发生变化，下游影响对 髓样细胞的存活和功能。这将使用从携带的个体中分离出的白细胞进行测试 IRGM主要等位基因或疾病风险等位基因，评估自噬，线粒体，代谢和功能输出。