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）：肠道性菌群的肠道发育和脊椎动物中的粘膜免疫需要。但是，对于这些过程发生的机制知之甚少。兔子的先前工作表明，在免疫前抗体库发展过程中，Ig基因的体细胞超突变（SHM）和基因转化率（GC）也需要肠道分子菌群，而B细胞的选择也需要B细胞的选择，这两者都发生在肠肠gut菌相关的淋巴机（GALT）中。通过将精选细菌菌株引入无菌galt，我们发现某些但并非所有共生生物具有诱导Ig基因的Galt发育以及SHM和GC的能力。我们确定了两种共同的微生物，分布氏芽孢杆菌和枯草芽孢杆菌，它们共同诱导了这些过程。但是，单独提出，两种生物都没有诱导这些过程。这项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。第一个具体目的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属于它们在Galt上皮上所吸收的方式。测试此测试的实验包括将细菌引入无收获的附录中，然后进行原位杂交和免疫荧光，以确定细菌在哪些细胞局部定位。下一个特定目标是使用在重组腺病毒中表达的可溶受体，将研究树突状细胞（DC）是通过分泌B细胞生长因子，BAFF还是抑制DC的transepithelial transepithelial in Vivo的分泌来促进GALT发育和Ig基因多样化。在AIM 3中，将通过抑制可溶性CTLA4和B-T细胞与可溶性CD40的T细胞的激活来研究T细胞帮助的需求，这均在重组腺病毒中产生。在AIM 4中，实验旨在寻找B细胞超抗原，该B细胞超抗原可引起galt的发育和主要抗体库的躯体多样化。这些实验很重要，因为肠道的腔含有比人体的所有其他细胞多的细菌细胞更多的细菌细胞，但是我们对这些生物的贡献对人类健康和疾病（例如过敏和炎症性肠病）的贡献知之甚少。