Humoral immunodeficiency disrupts bile-acid-induced immune tolerance in the small intestine

项目摘要 体液免疫缺陷是人类原发性免疫缺陷最常见的诊断形式。 常见变异型免疫缺陷（CVID）是临床上最严重的形式，慢性胃肠道免疫缺陷（CVID）是一种常见的免疫缺陷。 并发症在CVID患者中是常见的，并且对静脉内IG疗法的治疗是难治的。严重 胃肠道疾病被称为“CVID肠病”;一种小肠（SI）特异性肠病，临床表现为 慢性腹泻和吸收不良。胆汁酸（BA）是由肝脏产生并分泌到肝脏中的乳化剂。 促进膳食脂质和脂溶性维生素溶解和吸收的肠道。他们也可以服务于 作为能够在组织驻留免疫细胞中诱导致耐受性应答的信号分子。粘膜 抗体缺乏会改变微生物群的组成。鉴于微生物群深刻地影响了管腔BA 生物化学，总体假设，这R 01建议将解决的是，粘膜抗体- 缺乏导致异常的细菌BA代谢，其破坏BA诱导的免疫应答。 对SI的宽容。在这个建议中，我们提供的证据支持粘膜抗体缺乏的结果， 在与SI肠病的发展相关的异常炎性免疫应答中; 可能由引起BA吸收不良（BAM）的细菌胆盐水解酶（bsh）活性升高驱动。 我们还发现，bsh消融或口服BA补充剂可加重BAM并抑制炎症反应。 疾病具体目标#1的目的是确定体液免疫如何影响BA稳态， 这如何协调SI中致耐受性免疫表型的建立。几种互补模式 将用于解决这一基本问题，并将采用先进的超纯技术， 液相色谱质谱法（UPLC-MS）以全面表征BA合并液组成， 并配对高参数流式细胞术和单细胞RNA测序来表征SI驻留免疫 细胞表型具体目标#2的目的是证明粘膜抗体缺乏如何影响 SI驻留微生物群落的组成和BA代谢能力。一些小说和 互补的微生物定植模型、过继转移模型和下一代测序方法 将被用来解决这个问题。具体目标#3的目的是测试两种候选方法的有效性 减轻炎性SI肠病，并涉及口服BA补充或药物敲低 细菌的BSH活性。这项研究的创新包括首次分析了体液免疫的作用 发挥调节BA代谢、综合评价粘膜伊加和IgM抗体的作用 反应在SI稳态中起作用，表征了生态失调驱动疾病的新机制， 和表征bsh消融和口服BA补充在耐受性重编程中的作用。 慢性疾病背景下的SI驻留免疫细胞。除此之外，CVID，这项工作的结果与 人类的其他SI肠病，包括克罗恩病、乳糜泻和热带口炎性腹泻。

Project Summary Humoral immunodeficiency is the most frequently diagnosed form of primary immunodeficiency in humans. Common variable immunodeficiency (CVID) is the most clinically severe form, and chronic gastrointestinal complications are both common in CVID patients and refractory to treatment by intravenous Ig therapy. A severe GI disorder is termed 'CVID enteropathy'; a small intestine (SI)-specific enteropathy that presents clinically as chronic diarrhea and malabsorption. Bile acids (BAs) are emulsifiers produced by the liver and secreted into the gut that promote the solubilization and absorption of dietary lipids and lipid-soluble vitamins. They may also serve as signaling molecules capable of inducing tolerogenic responses in tissue-resident immune cells. Mucosal antibody deficiency alters microbiota composition. Given that the microbiota profoundly influence luminal BA biochemistry, the overarching hypothesis this R01 proposal will address is that mucosal antibody- deficiency results in aberrant bacterial BA metabolism that abolishes BA-induced immunological tolerance in the SI. In this proposal, we provide evidence supporting that mucosal antibody-deficiency results in aberrant inflammatory immune responses that are associated with the development of SI enteropathy; potentially driven by elevated bacterial bile salt hydrolase (bsh) activity that causes BA malabsorption (BAM). We also identify that bsh ablation or oral BA supplementation alleviates BAM and suppresses inflammatory disease. The objective of Specific Aim #1 is to define how humoral immunity influences BA homeostasis, and how this coordinates establishment of a tolerogenic immune phenotype in the SI. Several complementary models will be utilized to address this fundamental question and will incorporate the advanced techniques of ultra-purity liquid chromatography mass spectrometry (UPLC-MS) to comprehensively characterize BA pool composition, and paired high-parameter flow cytometry and single cell RNA sequencing to characterize SI-resident immune cell phenotypes. The objective of Specific Aim #2 is to demonstrate how mucosal antibody deficiency influences the composition and BA-metabolizing capacity of the SI-resident microbial community. Several novel and complementary microbial colonization models, adoptive transfer models, and next-gen sequencing approaches will be utilized to address this. The objective of Specific Aim #3 is to test the efficacy of two candidate approaches to alleviate inflammatory SI enteropathies and involve oral BA supplementation or pharmacological knockdown of bacterial bsh activity. Innovations from this research include the first analysis of the role of humoral immunity plays in regulating BA metabolism, a comprehensive assessment of the role mucosal IgA and IgM antibody responses play in SI homeostasis, characterization of a novel mechanism by which dysbiosis drives disease, and characterization of the role bsh ablation and oral BA supplementation play in tolerogenic re-programming of SI-resident immune cells in the setting of chronic disease. Beyond, CVID, results of this work are relevant to other SI enteropathies in humans including Crohn's disease, celiac disease, and tropical sprue.