Genes Mediating Innate Immune Suppression by Hypercapnia in Mammals and Flies

哺乳动物和果蝇高碳酸血症介导先天免疫抑制的基因

• 批准号: 8392235
• 负责人: GREG J BEITEL
• 金额: $ 35.52万
• 依托单位: NORTHWESTERN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-12-15 至 2015-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8392235
• 关键词: Acute; Adult; Adverse effects; Bacterial Infections; Binding; Blood; CCL2 gene; Candidate Disease Gene; Carbon Dioxide; Cause of Death; Cells; ChIP-seq; Chromatin; Chronic; Chronic Obstructive Airway Disease; Clinical; Communities; Complex; Data; Defect; Drosophila genus; Foundations; Future; Gene Components; Gene Expression; Gene Targeting; Genes; Genetic Transcription; Histones; Homologous Gene; Host Defense; Human; Hypercapnia; Immune; Immune Response Genes; Immunosuppression; Immunosuppressive Agents; In Vitro; Individual; Infection; Inflammatory; Interleukin-6; Lung; Lung diseases; Mammals; Mediating; Mediator of activation protein; Molecular; Mus; Mutation; Natural Immunity; Orthologous Gene; Outcome; Pathway interactions; Patients; Phagocytes; Play; Pneumonia; Predisposition; Proteins; Pseudomonas aeruginosa; RNA Interference; Regulator Genes; Risk; Risk Factors; Role; System; TNFRSF5 gene; Testing; Time; Tissues; Validation; Zinc Fingers; antimicrobial peptide; bacterial resistance; base; fly; genome-wide; histone methyltransferase; homeodomain; in vivo; macrophage; mortality; mouse model; p65; prevent; promoter; response; transcription factor

DESCRIPTION (provided by applicant): Hypercapnia, elevation of PCO2 in blood and tissue, commonly occurs in severe acute and chronic lung disorders, such as chronic obstructive pulmonary disease (COPD). Patients with advanced COPD frequently develop bacterial lung infections, and hypercapnia is a risk factor for mortality in such individuals, as in those with community-acquired pneumonia. We have shown that hypercapnia suppresses transcription of innate immune response genes required for host defense in human, mouse and Drosophila cells, and increases mortality due to bacterial infections in mice and Drosophila. These findings suggest that hypercapnia is not simply a marker of advanced lung disease, but plays a causal role in poor clinical outcomes by increasing susceptibility to infection. Our data also strongly suggest that hypercapnia inhibits innate immunity and host defense by pathway(s) conserved from Drosophila to mammals. Because the molecular mediator(s) of hypercapnic immune suppression are undefined, we conducted a genome-wide RNAi screen in cultured Drosophila cells, which identified ~140 genes required for hypercapnic suppression of antimicrobial peptide (AMP) genes. The 5 most potent of these candidate CO2-mediators encode the zinc finger homeodomain transcription factor, Zfh2; a histone deactylase; a histone methyltransferase; a chromatin-associated Ig-repeat protein; and a Rac-interacting protein. None of these genes were previously known to have immunoregulatory function. Exciting new data indicate that mutations in zfh2 protect adult Drosophila against CO2-induced host defense defects. Thus, we hypothesize that Zfh2 and the proteins encoded by the other 4 candidate genes are components of pathway(s) by which hypercapnia suppresses innate immune gene expression and host defense in Drosophila, and that the mammalian orthologs of these genes mediate hypercapnic suppression of innate immune/host defense genes in mouse and human phagocytes. In the case of Zfh2 and its mammalian orthologs, ZFHX3 and ZFHX4, we further hypothesize that hypercapnia alters their abilities to bind target gene promoters or components of the NF-:B transcriptional complex, or modifies the transcriptional activity of these factors, thereby decreasing expression of specific innate immune/host defense genes. In the proposed studies, we will test these hypotheses in vitro using cultured fly, mouse and human macrophages, and in vivo using adult Drosophila and lung inflammatory cells obtained from mice with Pseudomonas aeruginosa pneumonia. These studies will for the first time define components of conserved pathway(s) by which hypercapnia impairs innate immunity and host defense, and determine their mechanisms of action. The results should lay the basis for future studies aimed at preventing hypercapnic immune suppression in patients with advanced lung disease.

描述（由申请人提供）：高碳酸血症，即血液和组织中 PCO2 升高，通常发生在严重的急性和慢性肺部疾病中，例如慢性阻塞性肺病 (COPD)。晚期慢性阻塞性肺病患者经常出现细菌性肺部感染，高碳酸血症是此类患者死亡的危险因素，就像社区获得性肺炎患者一样。我们已经证明，高碳酸血症会抑制人类、小鼠和果蝇细胞中宿主防御所需的先天免疫反应基因的转录，并增加小鼠和果蝇因细菌感染而导致的死亡率。这些发现表明，高碳酸血症不仅仅是晚期肺部疾病的一个标志，而且通过增加感染的易感性，在不良的临床结果中发挥着因果作用。我们的数据还强烈表明，高碳酸血症通过从果蝇到哺乳动物保守的途径抑制先天免疫和宿主防御。由于高碳酸血症免疫抑制的分子介质尚不清楚，我们在培养的果蝇细胞中进行了全基因组 RNAi 筛选，确定了抗菌肽 (AMP) 基因高碳酸血症抑制所需的约 140 个基因。这些候选 CO2 介体中 5 个最有效的编码锌指同源域转录因子 Zfh2；组蛋白脱乙酰酶；组蛋白甲基转移酶；染色质相关 Ig 重复蛋白；和 Rac 相互作用蛋白。以前不知道这些基因具有免疫调节功能。令人兴奋的新数据表明，zfh2 的突变可以保护成年果蝇免受二氧化碳诱导的宿主防御缺陷的影响。因此，我们假设 Zfh2 和其他 4 个候选基因编码的蛋白质是高碳酸血症抑制果蝇先天免疫基因表达和宿主防御的途径的组成部分，并且这些基因的哺乳动物直系同源物介导高碳酸血症抑制先天免疫基因表达和宿主防御。小鼠和人类吞噬细胞中的免疫/宿主防御基因。就 Zfh2 及其哺乳动物直系同源物 ZFHX3 和 ZFHX4 而言，我们进一步假设高碳酸血症改变了它们结合靶基因启动子或 NF-:B 转录复合物成分的能力，或改变了这些因子的转录活性，从而降低了表达特定的先天免疫/宿主防御基因。在拟议的研究中，我们将使用培养的果蝇、小鼠和人类巨噬细胞在体外测试这些假设，并使用从患有铜绿假单胞菌肺炎的小鼠获得的成年果蝇和肺部炎症细胞在体内测试这些假设。这些研究将首次定义高碳酸血症损害先天免疫和宿主防御的保守途径的组成部分，并确定其作用机制。这些结果应该为未来旨在预防晚期肺病患者高碳酸血症免疫抑制的研究奠定基础。