IRGM proteins as regulators of inflammation

IRGM 蛋白作为炎症调节因子

• 批准号: 10549864
• 负责人: Joern Coers
• 金额: $ 47.63万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-02-07 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10549864
• 关键词: Address; Affect; Ankylosing spondylitis; Autophagocytosis; Bacteria; Binding; Binding Proteins; CASP4 gene; Cell Line; Cells; Collection; Crohn' s disease; Cytoplasm; Data; Development; Disease; Dynamin; Endogenous Factors; Endosomes; Etiology; Event; Excision; Genes; Goals; Golgi Apparatus; Guanosine Triphosphate Phosphohydrolases; Host Defense; Human; Immune; Immune System Diseases; Immune response; Immunity; In Vitro; Infection; Inflammasome; Inflammation; Inflammatory; Ingestion; Interferons; Intestinal Perforation; Intracellular Membranes; Knock-out; Knockout Mice; Knowledge; Lead; Link; Macrophage; Mediating; Membrane; Messenger RNA; Metabolic; Metabolic Pathway; Metabolism; Microbe; Mitochondria; Modeling; Molecular; Molecular Target; Morbidity - disease rate; Mus; Outcome; Pathway interactions; Predisposition; Process; Production; Protein Isoforms; Proteins; Publishing; RNA Splicing; Regulation; Resistance; Role; Sepsis; Series; Shapes; Signal Pathway; Signal Transduction; System; TLR4 gene; Testing; Tuberculosis; Variant; Work; antimicrobial; clinically relevant; cytokine; extracellular; gastrointestinal; gene therapy; glucose metabolism; human model; immunoregulation; improved; in vivo; inflammatory modulation; inhibitor; molecular diagnostics; mortality; mouse model; non-alcoholic fatty liver disease; novel; novel diagnostics; novel therapeutics; pathogen; pathogenic bacteria; pharmacologic; polymicrobial sepsis; protein function; response; sensor; septic patients; trafficking; translational impact; uptake

ABSTRACT Hypomorphic variants of the Immunity Related GTPase (IRG) M gene are associated with poor outcomes for sepsis patients; however, the underlying mechanism is not known. IRGM and its mouse orthologues are produced at high levels in response to LPS and/or interferons, particularly in macrophages. Although prior work has shown that IRGM proteins bind intracellular membranes and modulate immune responses that restrict survival of intracellular pathogens, their primary roles in inflammation - independent of their roles in cell- autonomous host defense - are mostly unexplored. As instructed by extensive preliminary data, this proposal will address the novel hypothesis that IRGM proteins directly downmodulate the production of inflammatory cytokines in response to LPS, and that they do so through at least two distinct mechanisms: (1) by shaping metabolic pathways that regulate activation of the extracellular LPS sensor TLR4, and (2) by modulating intracellular processing of ingested LPS to limit activation of the cytosolic LPS sensor Casp11 (CASP4). We will test these two non-exclusive mechanisms by which IRGM proteins dampen pro-inflammatory signaling in mouse and human macrophages in vitro, as well as define the roles of IRGM proteins in sepsis and antimicrobial inflammation in vivo. Aim1 will determine the impact of IRGM proteins on mitochondrial function, metabolite levels, glucose metabolism, and cytokine production in response to TLR4 activation. Causation between altered metabolism and/or mitochondrial function and altered cytokine expression will be established through pharmacological and genetic interventions. Aim2 will explore the role of IRGM proteins in the processing and sensing of cytoplasmic LPS and define the mechanism(s) by which IRGM deficiencies lead to LPS-triggered Casp11 hyperactivation. Aim3 will determine how changes in IRGM protein function impact TLR4- and /or Casp11-dependent sepsis in vivo. Instructed by our finding that IRGM insufficiency leads to excessive inflammatory cytokine production to LPS in vivo, we will define the consequences of IRGM protein insufficiencies on morbidity and survival in clinically relevant sepsis mouse models. Newly generated conditional Irgm knockout models and a pan-Irgm knockout mouse will be used to determine cell-specific roles for Irgm proteins and the interdependent functions of Irgm isoforms. Collectively, our studies will not only provide a mechanistic understanding of IRGM proteins as negative regulators of LPS-activated proinflammatory signaling pathways but also define the relevance of these regulatory processes in determining the outcome of different sepsis subtypes.

抽象的 免疫相关 GTP 酶 (IRG) M 基因的亚形变体与不良预后相关 败血症患者；然而，根本机制尚不清楚。 IRGM 及其小鼠直系同源物是 对 LPS 和/或干扰素产生高水平的反应，特别是在巨噬细胞中。虽然之前的工作 已经表明 IRGM 蛋白结合细胞内膜并调节免疫反应，限制 细胞内病原体的存活，它们在炎症中的主要作用 - 独立于它们在细胞中的作用 - 自主宿主防御——大多尚未探索。根据大量初步数据的指示，该提案 将解决 IRGM 蛋白直接下调炎症产生的新假设 细胞因子对 LPS 做出反应，并且它们通过至少两种不同的机制来做到这一点：（1）通过塑造 调节细胞外 LPS 传感器 TLR4 激活的代谢途径，以及 (2) 通过调节 对摄入的 LPS 进行细胞内处理，以限制胞质 LPS 传感器 Casp11 (CASP4) 的激活。我们将 测试 IRGM 蛋白抑制小鼠促炎信号传导的这两种非排他性机制 和体外人类巨噬细胞，以及定义 IRGM 蛋白在脓毒症和抗菌中的作用 体内有炎症。 Aim1 将确定 IRGM 蛋白对线粒体功能、代谢物的影响 水平、葡萄糖代谢和细胞因子产生响应 TLR4 激活。改变之间的因果关系 代谢和/或线粒体功能以及细胞因子表达的改变将通过 药理学和遗传干预。 Aim2 将探索 IRGM 蛋白在加工和 细胞质 LPS 的传感并定义 IRGM 缺陷导致 LPS 触发的机制 Casp11 过度激活。 Aim3 将确定 IRGM 蛋白功能的变化如何影响 TLR4-和/或 体内 Casp11 依赖性败血症。根据我们的发现，IRGM 不足会导致过度 体内炎症细胞因子产生 LPS，我们将定义 IRGM 蛋白不足的后果 临床相关脓毒症小鼠模型的发病率和生存率。新生成的条件性 Irgm 敲除 模型和泛 Irgm 敲除小鼠将用于确定 Irgm 蛋白的细胞特异性作用和 Irgm 同种型的相互依赖的功能。总的来说，我们的研究不仅提供了一个机制 了解 IRGM 蛋白作为 LPS 激活的促炎信号通路的负调节因子 还定义了这些监管过程在确定不同脓毒症结果方面的相关性 亚型。