Mechanisms of Chronic Nod2-mediated Effects in Human Macrophages

Nod2 介导的人巨噬细胞慢性作用的机制

• 批准号: 7850040
• 负责人: CLARA ABRAHAM
• 金额: $ 3.58万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-17 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7850040
• 关键词: Abbreviations; Acetylmuramyl-Alanyl-Isoglutamine; Acute; Address; Affect; Antigen-Presenting Cells; Arrestins; Bacteria; Boxing; Caspase; Cell Nucleus; Cell Wall; Cells; Chronic; Crohn' s disease; Cytoplasm; Defect; Dendritic Cells; Development; Down-Regulation; Environment; Equilibrium; Exhibits; Exposure to; Figs - dietary; Functional disorder; Genetic Polymorphism; Hand; Heterogeneity; Human; Hydrochloride Salt; IRAK1 gene; IRAK3 gene; Immune system; Individual; Individual Differences; Inflammatory; Inflammatory Bowel Diseases; Intestines; Lead; Leucine-Rich Repeat; Ligands; MAP Kinase Gene; MAP3K7 gene; MAPK14 gene; MAPK8 gene; Mediating; Mitogen-Activated Protein Kinases; Mutation; Nucleotides; Organism; Outcome; Pathway interactions; Pattern recognition receptor; Peptidoglycan; Peripheral; Production; Proteins; RIPK2 gene; Role; Signal Pathway; Signal Transduction; TLR2 gene; TLR4 gene; TNFRSF5 gene; TOLLIP gene; TRAF6 gene; Testing; Tissues; Toll-Like Receptor 2; Toll-Like Receptor Pathway; Toll-like receptors; Transcriptional Activation; Ulcerative Colitis; Up-Regulation; base; comparative; cytokine; gastrointestinal; human IRAK1 protein; human disease; innovation; insight; loss of function; macrophage; microbial; monocyte; peptidoglycan receptor; public health relevance; receptor; response

DESCRIPTION (provided by applicant): A unique challenge faced by the intestinal immune system is the requirement for tolerance to luminal bacteria while simultaneously defending against pathogenic organisms. The dysregulation of this balance can lead to uncontrolled activation of the gastrointestinal immune system, a feature of Crohn's disease and ulcerative colitis. The recognition and response to microbial organisms is mediated in part by pattern recognition receptors (PRR), which include nucleotide oligomerization domain 2 (NOD2), an intracellular bacterial recognition receptor for peptidoglycan (PGN), a component of both gram positive and gram negative cell walls. Crohn's disease is associated with loss-of-function polymorphisms in NOD2 (CARD15). However, the specific NOD2 dysfunction(s) leading to the development of Crohn's disease is not yet understood. Upon acute stimulation of NOD2, either alone or in combination with other bacterial receptors, peripherally-derived antigen presenting cells (APC) secrete proinflammatory cytokines. Intestinal macrophages and dendritic cells (DC) are in large part derived from circulating monocytes that migrate into the intestinal tissues and undergo differentiation based on the intestinal environment. The intestinal immune system is an environment which results in chronic stimulation. Therefore, it is critical to understand the consequences of chronic stimulation through NOD2. We have recently found that chronic stimulation through NOD2 in primary peripheral monocyte-derived human macrophages results in reduced production of pro- inflammatory cytokines upon restimulation either through NOD2 or through other PRR. This downregulation in production of pro-inflammatory cytokine secretion is similar to the tolerance, or significantly reduced secretion of pro-inflammatory cytokines, exhibited by intestinal macrophages stimulated with bacterial products. On the other hand, intestinal APC from individuals with inflammatory bowel disease (IBD) have excess production of pro-inflammatory cytokines. We hypothesize that the tolerance induced in primary human APC upon stimulation through NOD2 is mediated by a combination of mechanisms that selectively affect specific signaling pathways (e.g. pro-inflammatory cytokines), and that some of these mechanisms are different than those mediated by chronic stimulation of Toll like receptors (TLR). This proprosal will define the tolerance defects in human peripheral macrophages expressing the various Crohn's disease- associated NOD2 mutations, the mechanisms mediating peripheral macrophage tolerance through chronic NOD2 versus TLR stimulation, and then extend these findings directly into human intestinal macrophages. PUBLIC HEALTH RELEVANCE We have recently found that chronic stimulation through NOD2 in primary peripheral monocyte-derived human macrophages results in reduced production of proinflammatory cytokines upon restimulation either through NOD2 or through other pattern recognition receptors. We seek to define the combination of NOD2-mediated mechanisms that selectively affect the downregulation of these pro-inflammatory cytokines, and determine if these mechanisms are different from those induced upon chronic stimulation of Toll like receptors. We will then extend these findings directly into human intestinal macrophages and determine if individuals harboring Crohn's disease associated NOD2 mutations are defective in these mechanisms.

描述（由申请人提供）：肠道免疫系统面临的一个独特挑战是需要对肠腔细菌具有耐受性，同时防御病原微生物。这种平衡的失调会导致胃肠道免疫系统不受控制地激活，这是克罗恩病和溃疡性结肠炎的一个特征。对微生物的识别和反应部分由模式识别受体 (PRR) 介导，其中包括核苷酸寡聚结构域 2 (NOD2)，肽聚糖 (PGN) 是细胞内细菌识别受体，肽聚糖是革兰氏阳性细胞和革兰氏阴性细胞的组成部分墙壁。克罗恩病与 NOD2 (CARD15) 功能丧失多态性有关。然而，导致克罗恩病发生的具体 NOD2 功能障碍尚不清楚。当 NOD2 单独或与其他细菌受体联合急性刺激时，外周源性抗原呈递细胞 (APC) 会分泌促炎细胞因子。肠道巨噬细胞和树突状细胞（DC）很大程度上来源于循环单核细胞，它们迁移到肠道组织中并根据肠道环境进行分化。肠道免疫系统是一个导致慢性刺激的环境。因此，了解 NOD2 慢性刺激的后果至关重要。我们最近发现，在原代外周单核细胞衍生的人巨噬细胞中，通过NOD2进行慢性刺激，在通过NOD2或通过其他PRR再刺激时，会导致促炎细胞因子的产生减少。这种促炎细胞因子分泌产生的下调类似于细菌产物刺激的肠道巨噬细胞所表现出的耐受性或促炎细胞因子分泌的显着减少。另一方面，炎症性肠病 (IBD) 患者的肠道 APC 会产生过量的促炎细胞因子。我们假设原代人 APC 在通过 NOD2 刺激后诱导的耐受性是由选择性影响特定信号通路（例如促炎细胞因子）的机制组合介导的，并且其中一些机制与慢性刺激介导的机制不同。 Toll 样受体 (TLR)。该提案将定义表达各种克罗恩病相关 NOD2 突变的人外周巨噬细胞的耐受缺陷，通过慢性 NOD2 与 TLR 刺激介导外周巨噬细胞耐受的机制，然后将这些发现直接扩展到人肠道巨噬细胞。 公共健康相关性我们最近发现，在原代外周单核细胞衍生的人巨噬细胞中通过NOD2进行慢性刺激会导致在通过NOD2或通过其他模式识别受体再刺激时促炎细胞因子的产生减少。我们试图定义 NOD2 介导的选择性影响这些促炎细胞因子下调的机制的组合，并确定这些机制是否与慢性刺激 Toll 样受体所诱导的机制不同。然后，我们将这些发现直接扩展到人类肠道巨噬细胞，并确定携带克罗恩病相关 NOD2 突变的个体在这些机制中是否存在缺陷。