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Immunoregulatory Defects In Inflammatory Bowel Disease

炎症性肠病的免疫调节缺陷

基本信息

批准号：
10014020
负责人：
Warren Strober
金额：
$ 49.77万
依托单位：
NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10014020
关键词：
Acetylmuramyl-Alanyl-Isoglutamine Affect Alleles Arthritis Binding Blau syndrome Cells Colitis Crohn&apos s disease Defect Development Dimerization Disease Distant Dominant-Negative Mutation Exanthema Exhibits Failure Family Functional disorder Gastrointestinal Diseases Gastrointestinal tract structure Genes Genetic Polymorphism Granulomatous IRF4 gene Immune response Impairment Individual Inflammation Inflammatory Inflammatory Bowel Diseases Innate Immune Response Intestines Knock-in Knock-in Mouse Lead Leucine Ligands Mediating Molecular Molecular Abnormality Mucosal Immune System Mus Mutate Mutation NF-kappa B Nucleotides Organism Patients Procedures RIPK2 gene Regulation Risk Signal Transduction Site Sterility Subfamily lentivirinae Tissues Ubiquitination Ulcerative Colitis Uveitis disease-causing mutation dysbiosis gut microbiota immunoregulation microbiota microorganism overexpression patient subsets prevent response sensor theories

项目摘要

To probe the mechanism of disease caused by mutations in the NBD of NOD2 we first determined the capacity of over-expressed intact NOD2 or NOD2 with a Blau mutation (BS-NOD2) (R314W) to cross (down)-regulate TLR responses underlying TNBS-colitis. Whereas over-expression of intact NOD2 protected mice from TNBS-colitis, over-expression of BS-NOD2 failed to protect. These findings were corroborated by studies of mice bearing a knock-In mutation of NOD2 similar to that in patients with BS in which we showed that such mice were not as protected from DSS-colitis by NOD2-ligand (muramyl dipeptide, MDP) administration as was comparably treated littermate control mice. Importantly, these failure to protect was also noted in heterozygous mice in which the mutation occurred on only one allele; thus the mutated NOD2 exerted a dominant negative effect which explained the fact that the Blau mutation has an autosomal dominant effect. Studies conducted to investigate the molecular basis of these cross-regulatory defects indicated that BS-NOD2 expressed in HEK293T cells exhibit a reduced ability to oligomerize, interact with or activate RIPK2 and activate NF-kappaB. In addition, MDP-stimulated cells from BS-NOD2 KI mice fail to up-regulate expression of IRF4, a factor that has been shown to mediate NOD2 cross-regulation by de-ubiquitination of NF-kappaB signaling components. Indeed, lack of IRF4-mediated cross-regulatory function in KI cells was shown by the fact that enhanced TLR responses exhibited by these cells are suppressed by lentivirus transduction of IRF4. Overall, these studies indicate that NOD2 bearing a BS mutation lacks the ability to cross-regulate TLR responses via its inability to activate IRF4. The mutation thus renders BS patients susceptible to excessive TLR responses that have the potential to support inflammation at sterile tissue sites. Thus, the Blau mutation affecting NOD2 causes inflammatory disease by affecting NOD2 immunoregulatory function.

为了探索由N 0 D2的NBD中的突变引起的疾病的机制，我们首先确定了过表达的完整N 0 D2或具有Blau突变的N 0 D2（BS-N 0 D2）（R314 W）交叉（下调）调节TNBS-结肠炎的TLR应答的能力。而完整NOD 2的过表达保护小鼠免受TNBS结肠炎，BS-NOD 2的过表达未能保护。这些发现得到了携带NOD 2敲入突变的小鼠的研究的证实，这些小鼠与BS患者中的小鼠相似，其中我们表明，NOD 2配体（胞壁酰二肽，MDP）给药对这些小鼠的DSS-结肠炎保护作用不如经LPS处理的同窝对照小鼠。重要的是，在杂合子小鼠中也注意到这些保护失败，其中突变仅发生在一个等位基因上;因此突变的NOD 2产生显性负效应，这解释了Blau突变具有常染色体显性效应的事实。为研究这些交叉调节缺陷的分子基础而进行的研究表明，HEK 293 T细胞中表达的BS-NOD 2表现出寡聚化、与RIPK 2相互作用或激活RIPK 2以及激活NF-κ B的能力降低。此外，来自BS-NOD 2 KI小鼠的MDP刺激的细胞不能上调IRF 4的表达，IRF 4是一种已显示通过NF-κ B信号传导组分的去泛素化介导NOD 2交叉调节的因子。事实上，KI细胞中缺乏IRF 4介导的交叉调节功能，这一事实表明，这些细胞表现出的增强的TLR应答被IRF 4的慢病毒转导抑制。总之，这些研究表明，携带BS突变的NOD 2缺乏通过其不能激活IRF 4来交叉调节TLR应答的能力。因此，该突变使BS患者容易受到过度TLR反应的影响，这些反应有可能支持无菌组织部位的炎症。因此，影响NOD 2的Blau突变通过影响NOD 2免疫调节功能而引起炎性疾病。