Somatic Diversification of Immunoglobulin Genes in Galt

Galt 免疫球蛋白基因的体细胞多样化

• 批准号: 8321129
• 负责人: Katherine L. Knight
• 金额: $ 31.32万
• 依托单位: LOYOLA UNIVERSITY CHICAGO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8321129
• 关键词: Address; Adenoviruses; Agonist; Antibody Repertoire; Antigens; B-Lymphocytes; Bacteria; Bacteroides fragilis; Birth; CD28 gene; CTLA4 gene; Cell Communication; Cells; Dendritic Cells; Development; Disease; Epithelium; Gene Conversion; Generations; Goals; Gut associated lymphoid tissue; Health; Human; Human body; Hypersensitivity; Immunofluorescence Immunologic; Immunoglobulin Genes; Immunoglobulin Somatic Hypermutation; In Situ Hybridization; Inflammatory Bowel Diseases; Interleukin-4; Intestines; Kinetics; Lymphoid Tissue; Mucosal Immunity; Nature; Organism; Oryctolagus cuniculus; Pattern recognition receptor; Process; Recombinants; Site; Sterility; Superantigens; T-Cell Activation; T-Lymphocyte; TNFRSF5 gene; Testing; Up-Regulation; Vertebrates; Work; activation-induced cytidine deaminase; base; commensal microbes; cytokine; design; in vivo; microorganism; migration; mutant; prevent; receptor; research study; uptake

DESCRIPTION (provided by applicant): The intestinal commensal microbiota is required for development of lymphoid tissues and mucosal immunity in vertebrates. However, little is known of the mechanism by which these processes occur. Previous work in rabbits has demonstrated that the intestinal commensal microbiota is also required for somatic hypermutation (SHM) and gene conversion (GC) of Ig genes during development of the preimmune antibody repertoire, and for B cell selection, both of which occur in gut-associated lymphoid tissues (GALT). By introducing select bacterial strains into sterile GALT, we found that some but not all commensal organisms have the capacity to induce GALT development and SHM and GC of Ig genes. We identified two commensal microorganisms, B. fragilis and B. subtilis, that together, induced these processes; however, introduced singly, neither organism induced these processes. The goal of this study is to determine the mechanism by which these bacteria induce GALT development and SHM and GC of Ig genes, and why two bacteria are required. The first specific aim is to determine how bacteria enter the host, and if the difference in follicle-inducing bacteria and non-follicle-inducing bacteria resides in how they are taken up across the epithelium of GALT. Experiments to test this include introducing bacteria into germfree appendix and then performing in situ hybridization and immunofluorescence to determine in which cells the bacteria are localized. The next specific aim, by using soluble receptors expressed in recombinant adenovirus, will investigate whether dendritic cells (DC) contribute to GALT development and Ig gene diversification by secretion of the B cell growth factor, BAFF, or by inhibiting the transepithelial migration of DC in vivo. In Aim 3, the requirement for T cell help will be investigated by inhibiting the activation of T cells with soluble CTLA4 and B-T cell interactions with soluble CD40, both produced in recombinant adenovirus. In Aim 4, experiments are designed to search for a B cell superantigen that induces GALT development and somatic diversification of the primary antibody repertoire. These experiments are important because the lumen of the intestine contains 10X more bacterial cells than all other cells of the human body combined, and yet we know little about how these organisms contribute to human health and diseases such as allergy and inflammatory bowel disease.

描述（由申请人提供）：肠道共生微生物群是脊椎动物淋巴组织和粘膜免疫发育所必需的。然而，人们对这些过程发生的机制知之甚少。先前对兔子的研究表明，肠道共生微生物群也是免疫前抗体库发育过程中 Ig 基因的体细胞超突变 (SHM) 和基因转换 (GC) 以及 B 细胞选择所必需的，这两者都发生在肠道中。相关淋巴组织（GALT）。通过将选定的细菌菌株引入无菌 GALT，我们发现一些但并非所有共生生物具有诱导 GALT 发育以及 Ig 基因的 SHM 和 GC 的能力。我们鉴定了两种共生微生物，脆弱芽孢杆菌和枯草芽孢杆菌，它们共同诱导了这些过程。然而，单独引入时，这两种生物体都不会诱导这些过程。本研究的目的是确定这些细菌诱导 GALT 发育以及 Ig 基因的 SHM 和 GC 的机制，以及为什么需要两种细菌。第一个具体目标是确定细菌如何进入宿主，以及卵泡诱导细菌和非卵泡诱导细菌的差异是否在于它们如何被 GALT 上皮吸收。测试这一点的实验包括将细菌引入无菌阑尾，然后进行原位杂交和免疫荧光以确定细菌位于哪些细胞中。下一个具体目标是通过使用重组腺病毒中表达的可溶性受体，研究树突状细胞 (DC) 是否通过分泌 B 细胞生长因子 BAFF 或通过抑制 DC 的跨上皮迁移来促进 GALT 发育和 Ig 基因多样化。体内。在目标 3 中，将通过可溶性 CTLA4 抑制 T 细胞的活化以及 B-T 细胞与可溶性 CD40 的相互作用（两者均由重组腺病毒产生）来研究对 T 细胞帮助的需求。在目标 4 中，实验旨在寻找诱导 GALT 发育和一抗库体细胞多样化的 B 细胞超抗原。这些实验很重要，因为肠腔中的细菌细胞数量比人体所有其他细胞的总和多 10 倍，但我们对这些生物体如何影响人类健康和过敏和炎症性肠病等疾病知之甚少。