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）：我们每个人都拥有数万亿微生物的独特集合，从而形成“超有机体”，其中微生物细胞的数量超过人类细胞的数量估计数量级。我们的肠道含有绝大多数这些微生物。微生物群落稳定性的来源，以及个体免疫系统和微生物群的共同进化促成共生关系的机制知之甚少：答案应该提供重要线索，说明微生物群如何促进我们的健康，微生物群的扰动如何影响我们的健康。生态学的出现，这种扰动如何产生某些病理状态（例如，感染性腹泻；炎症性肠病），以及如何开发新策略来有意操纵微生物群的成分具有治疗功效。我在无菌 Rag1-/- 小鼠中开发了人类肠道微生物群的简化模型，其中肠道微生物群的多样性被减少到一个物种（Bacteroides thetaiotaomicron，正常人类肠道微生物群的一个重要的测序成员），并且库适应性免疫系统对一种免疫球蛋白的影响。我已经表征了这种独特的免疫球蛋白 A (IgA) 的特异性，这种细菌是通过在无菌小鼠中定植而自然引发的。单克隆抗体 (225.4) 与 B. thetaiotaomicron 的荚膜多糖 4 (CPS4) 基因座的产物发生反应。对具有或不具有产生这种抗体的杂交瘤细胞的无菌 Rag1-/- 小鼠进行定植表明，针对该荚膜表位的工程化 IgA 反应随后减少了促炎信号传导，抑制表位表达并影响细菌竞争力。这些发现表明，肠道的“耐受性”是指尽管免疫识别其微生物群成员，但未能发展出病理性炎症。在目标 1 中，我建议使用无菌小鼠来表征具有与 225.4 不同表位特异性的其他抗体，以及不同同种型的抗体，并使用微生物和宿主的功能基因组分析来定义每种抗体和各种组合的作用抗体影响宿主共生体稳态。在目标 2 中，我将开发一种抗共生 B 细胞受体限生转基因敲入小鼠，以评估特定抗体反应对宿主-共生体稳态的发展和长期影响。 相关性：了解我们如何与消化道中的数万亿细菌共存并从中受益，对于了解我们的健康以及各种疾病（包括感染性腹泻和结肠炎）的起源非常重要。我将评估免疫反应的一部分（称为免疫球蛋白 A）如何预防炎症。了解这种反应通常是如何发生的以及它是如何发挥作用的，将有助于未来诊断测试和炎症介导疾病的治疗的发展。