Commensal-dependent maturation of the natural IgM repertoire

天然 IgM 库的共生依赖性成熟

• 批准号: 9120659
• 负责人: James Stewart New
• 金额: $ 3.51万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-02 至 2018-07-01
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9120659
• 关键词: Adult; Affect; Allergic Disease; Animal Model; Antibodies; Antibody Repertoire; Antibody Specificity; Antigens; Apoptotic; Autoantigens; Autoimmune Diseases; B cell repertoire; B-Lymphocytes; Bacteria; Bone Marrow; CD15 Antigens; Cell Lineage; Cell Wall; Cells; Development; Disease; Disease model; Engineering; Epitopes; Evaluation; Fluorescence-Activated Cell Sorting; Frequencies; Gastrointestinal tract structure; Generations; Genes; Germ-Free; Glucosamine; Gnotobiotic; Goals; Homeostasis; Humoral Immunities; Hypersensitivity; Immune; Immune system; Immunoglobulin A; Immunoglobulin M; Immunoglobulin Variable Region; Immunotherapy; Intestines; Lamina Propria; Lead; Libraries; Life; Maintenance; Microbe; Modeling; Monitor; Monoclonal Antibodies; Mus; Natural Immunity; Neonatal; Outcome; Peripheral; Phenotype; Phospholipids; Plasma Cells; Play; Polysaccharides; Population; Prevention; Recombinant DNA; Role; Serum; Shapes; Small Intestines; Sorting - Cell Movement; Source; Specificity; Spleen; Structure; System; T-Cell Development; T-Independent Antigens; T-Lymphocyte; Taxon; Testing; Time; Tissues; Work; base; commensal microbes; design; experience; germ free condition; gut microbiota; immunogenic; insight; member; microbial; microbiome; microbiota; microorganism; novel; public health relevance; reconstitution; research study; scaffold

 DESCRIPTION (provided by applicant): This proposal will determine how the intestinal microbiota shapes the development of innate-like B cells and the specificities of antibodies represented in the natural IgM (nIgM) repertoire. nIgM plays significant roles in maintenance of immunological homeostasis and the clearance of potentially immunogenic autoantigens represented on apoptotic cells, suppressing the development of autoimmune and allergic diseases. Innate-like B cells are the source of nIgM, and possess specificities for polysaccharide and phospholipid epitopes that are conserved between mammalian antigens and commensal bacteria harbored within the gut, however little is known regarding the impact of microbiota-derived antigens on the development of this subset of antibodies. Observations that innate-like B cells undergo antigen selection in the small intestine lamina propria leading to the differentiation of IgA secreting plasma cells in those tissues, and observations that mice maintained under germ free conditions experience exacerbated diseases in allergy models and in several autoimmune disease models led us to hypothesize that the microbiota plays a previously unappreciated role in shaping the systemic B cell repertoire and the generation of nIgM. We investigated the distribution of B cells specific for the T cell-independent (TI) antigen N-acetyl-D-Glucosamine (GlcNAc) between specific pathogen free and germ free mice and have found substantial evidence that intestinal colonization increases the numbers of B cells and levels of serum antibody specific for GlcNAc, while inducing shifts in the dominant immunoglobulin V-gene used to generate this specificity. To further dissect these interactions, we developed a novel fluorescence-activated cell sorting approach to study the distribution of TI antigens on species of commensal bacteria. Through simultaneous evaluation of the IgA opsonization status of these antigens, we expect to (i) identify immunologically relevant microorganisms bearing specific TI- antigens that interface with humoral immunity in the gut. Using gnotobiotic animal models, wherein germ free mice are reconstituted with flora enriched for particular antigenic determinants with the platform described above, we plan to test the hypothesis that antigen derived from the commensal micoflora leads to selection of B cell clonotypes into the nIgM-producing niche. We plan to test this hypothesis by (ii) evaluating the frequency and phenotype of splenic GlcNAc and Lewis X antigen-specific B cells following microbial reconstitution with bacteria commensal isolates enriched for these antigens, (iii) monitoring the generation of LP, spleen and bone marrow-localized plasma cells, and (iv) monitoring shifts in the B cell clonotypes composing those specificities. These experiments will demonstrate for the first time that interaction with exogenous antigen at peripheral tissues is required for development of a fully competent nIgM repertoire. This work will lead to the development of novel means of classifying the diversity of the intestinal microbiota, and offer valuable insight to the development of the nIgM repertoire value in designing immunotherapies aimed at boosting natural immunity.

 描述（由申请人提供）：该提案将确定肠道微生物群如何塑造先天类 B 细胞的发育以及天然 IgM (nIgM) 库中代表的抗体的特异性。 nIgM 在维持免疫稳态和清除凋亡细胞上潜在的免疫原性自身抗原、抑制自身免疫性疾病和过敏性疾病的发展方面发挥着重要作用。先天样 B 细胞是 nIgM 的来源，并且对多糖和磷脂表位具有特异性，这些表位在哺乳动物抗原和肠道内共生细菌之间保守，但关于微生物群衍生的抗原对这组抗体发育的影响知之甚少。观察到先天性 B 细胞在小肠固有层中经历抗原选择，导致这些组织中分泌 IgA 的浆细胞分化，并且观察到维持在无菌条件下的小鼠在过敏模型和几种自身免疫性疾病模型中经历了恶化的疾病，这使我们推测微生物群在塑造全身 B 细胞中发挥着以前未被认识到的作用 曲目和 nIgM 的产生。我们研究了对 T 细胞非依赖性 (TI) 抗原 N-乙酰基-D-葡萄糖胺 (GlcNAc) 特异性的 B 细胞在无特定病原体和无菌小鼠之间的分布，并发现大量证据表明肠道定植增加了 B 细胞的数量和对 GlcNAc 特异性的血清抗体水平，同时诱导用于产生这种特异性的显性免疫球蛋白 V 基因的变化。为了进一步剖析这些相互作用，我们开发了一种新型荧光激活细胞分选方法来研究 TI 抗原在共生细菌物种上的分布。通过同时评估这些抗原的 IgA 调理作用状态，我们期望 (i) 鉴定具有与肠道中的体液免疫相互作用的特定 TI 抗原的免疫相关微生物。使用无菌动物模型，其中利用上述平台用富含特定抗原决定簇的菌群重建无菌小鼠，我们计划测试以下假设：源自共生菌群的抗原导致 B 细胞克隆型选择进入产生 nIgM 的生态位。我们计划通过（ii）评估用富含这些抗原的细菌共生分离株进行微生物重建后脾脏 GlcNAc 和 Lewis X 抗原特异性 B 细胞的频率和表型，（iii）监测 LP、脾脏和骨髓局部浆细胞的生成，以及（iv）监测组成这些浆细胞的 B 细胞克隆型的变化来检验这一假设。 特殊性。这些实验将首次证明，在外周组织中与外源抗原的相互作用是开发完全有效的 nIgM 库所必需的。这项工作将导致开发对肠道微生物群多样性进行分类的新方法，并为开发 nIgM 库在设计旨在增强自然免疫力的免疫疗法中的价值提供宝贵的见解。