Adaptive Immune Response to Symbiotic Bacteria as a Mediator of Gut Homeostasis

对共生细菌的适应性免疫反应作为肠道稳态的调节剂

• 批准号: 7532192
• 负责人: DANIEL A PETERSON
• 金额: $ 12.66万
• 依托单位: UNIVERSITY OF NEBRASKA LINCOLN
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-03 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7532192
• 关键词: Antibodies; Antibody Formation; Antibody Repertoire; Antibody-Producing Cells; B-Cell Development; B-Lymphocytes; Bacteria; Bacterial Physiology; Bacteroides thetaiotaomicron; Bacteroidetes; Binding; Carbohydrates; Cells; Colitis; Collection; Communities; Depth; Development; Diagnostic tests; Diarrhea; Disease; Down-Regulation; Ecology; Engineering; Epithelium; Epitopes; Evolution; Failure; Flow Cytometry; Future; Gastrointestinal tract structure; Generations; Genes; Genome; Germ-Free; Gnotobiotic; Health; Homeostasis; Human; Hybridomas; Immune; Immune response; Immune system; Immunocompetent; Immunoglobulin A; Immunoglobulin Class Switching; Immunoglobulin M; Immunoglobulin Somatic Hypermutation; Immunoglobulins; Immunohistochemistry; In Situ; Individual; Inflammation; Inflammatory; Inflammatory Bowel Diseases; Intravenous; Investigation; Knock-in Mouse; Light; Location; Mediating; Mediator of activation protein; Microbe; Mind; Modeling; Monoclonal Antibodies; Mucous Membrane; Mus; Natural History; Numbers; Oral; Pathologic; Phenotype; Play; Polysaccharides; Population; Rag1 Mouse; Receptor Gene; Receptors, Antigen, B-Cell; Recording of previous events; Representation Component; Research Personnel; Reverse Transcriptase Polymerase Chain Reaction; Role; Route; Secretory Component; Series; Signal Transduction; Source; Specificity; Staging; System; T-Lymphocyte; Testing; Therapeutic; Time; Time Study; Transgenic Organisms; Tumor Burden; Week; antimicrobial; base; forging; functional genomics; in vivo; in vivo Model; member; microbial; microbial community; microbial host; microorganism interaction; pressure; prevent; programs; research study; response; tumor

DESCRIPTION (provided by applicant): Each of us harbors a distinct collection of trillions of microbes resulting in a 'supraorganism' where the number of microbial cells exceeds the number of human cells by an estimated order of magnitude. Our gut contains the vast majority of these microbes. The sources of microbial community stability, and the mechanisms by which co-evolution of an individual's immune system and microbiota contributes to the symbiotic relationship are poorly understand: the answers should provide important clues about how the microbiota contributes to our health, how perturbations in microbial ecology arise, how such perturbations produce certain pathologic states (e.g., infectious diarrheas; inflammatory bowel diseases) and how new strategies can be developed for intentionally manipulating the representation of components of the microbiota for therapeutic benefit. I have developed a simplified model of the human gut microbiota in gnotobiotic Rag1-/- mice, where the diversity of the gut microbiota is reduced to one species (Bacteroides thetaiotaomicron, a prominent sequenced member of the normal human gut microbiota), and the repertoire of the adaptive immune system to one immunoglobulin. I have characterized the specificity of this unique immunoglobulin A (IgA), which was naturally primed by colonization of germfree mice with this bacterium. The monoclonal antibody (225.4) reacts with the product of capsular polysaccharide 4 (CPS4) locus of B. thetaiotaomicron. Colonization of germfree Rag1-/- mice, with and without hydridoma cells that produce this antibody revealed that an engineered IgA response to this capsular epitope subsequently reduces pro-inflammatory signaling, suppresses epitope expression and impacts bacterial competitiveness. These finding indicate that 'tolerance' in the gut is a failure to develop pathological inflammation despite immune recognition of members of its microbiota. In Aim 1, I propose to use gnotobiotic mice to characterize additional antibodies with different epitope specificities than 225.4, as well as antibodies of different isotypes, and define, using functional genomic analyses of both the microbe and host, how each antibody, and various combinations of antibodies impact host-symbiont homeostasis. In Aim 2, I will develop an anti-symbiotic B cell receptor gnotobiotic transgenic-knock-in mouse to evaluate the development and long-term impact of a defined antibody response on host-symbiont homeostasis. Relevance: Understanding how we can co-exist with and benefit from the trillions of bacteria that reside in our digestive tract is important for understanding our health, and the origins of various diseases, including infectious diarrheas and colitis. I will evaluate how a part of the immune response, called immunoglobulin A, prevents inflammation. Understanding how this response is normally mounted and how it functions will allow the development of diagnostic test and treatments of inflammation mediated diseases in the future.

描述（由申请人提供）：我们每个人都有一个明显的数万亿微生物的集合，导致“超生物”，其中微生物细胞的数量超过了人类细胞数量的数量级。我们的肠道包含这些微生物的绝大多数。 The sources of microbial community stability, and the mechanisms by which co-evolution of an individual's immune system and microbiota contributes to the symbiotic relationship are poorly understand: the answers should provide important clues about how the microbiota contributes to our health, how perturbations in microbial ecology arise, how such perturbations produce certain pathologic states (e.g., infectious diarrheas; inflammatory bowel diseases) and如何制定新策略来有意操纵微生物群的组成部分以获得治疗益处。我已经开发了人类肠道菌群的简化模型，在gnotobiotic rag1 - / - 小鼠中，肠道菌群的多样性还原为一种物种（细菌thetaiotaomicron，thetaiotaomicron，thetaiotaomicron，正常人类肠道微生物群的著名序列成员），以及适应性免疫系统的依存量。我已经表征了这种独特的免疫球蛋白A（IgA）的特异性，该特异性是通过使用该细菌的无毛小鼠定殖的。单克隆抗体（225.4）与B. thetaiotaomicron的囊囊多糖4（CPS4）基因座的产物反应。带有和没有液化瘤细胞的无毛Rag1 - / - 小鼠的定殖表明，对该囊膜表位的工程IgA反应随后降低了促炎的信号，可抑制表位表达并影响细菌竞争力。这些发现表明，肠道中的“耐受性”是尽管对其微生物群的成员进行了免疫识别，但仍无法发展病理炎症。在AIM 1中，我建议使用gnotobirotic小鼠表征具有不同表位特异性不同的其他抗体，以及不同同型不同的抗体，并使用微微生物和宿主的功能基因组分析来定义，每种抗体和各种抗体的组合都如何影响宿主 - 抗体的组合。在AIM 2中，我将开发一种抗传染性B细胞受体gnotobiotic转基因敲击小鼠，以评估定义的抗体反应对宿主 - 共生型稳态的发育和长期影响。 相关性：了解我们如何与消化道中存在的数万亿个细菌并存并受益，这对于了解我们的健康以及包括感染性腹泻和结肠炎在内的各种疾病的起源很重要。我将评估一种称为免疫球蛋白A的免疫反应的一部分如何防止炎症。了解通常如何安装此反应以及它的功能将如何发展诊断测试和将来炎症介导的疾病的治疗。