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最常见的原发免疫缺陷诊断形式。 常见变异性免疫缺陷(CVID)是临床上最严重的形式，慢性胃肠道 并发症在CVID患者中是常见的，也是静脉注射Ig治疗难以治疗的。一场严重的 胃肠道疾病被称为“CVID肠病”；这是一种特定于小肠(SI)的肠病，临床表现为 慢性腹泻和吸收不良。胆汁酸(BAS)是一种乳化剂，由肝脏产生并分泌到肝脏 促进膳食脂肪和脂溶维生素的溶解和吸收的肠道。他们还可以服务于 作为能够在组织驻留免疫细胞中诱导耐受性反应的信号分子。粘膜 抗体缺乏会改变微生物群的组成。鉴于微生物区系对鲁米纳BA有着深远的影响 生物化学，这个R01提案将解决的首要假设是粘膜抗体- 缺乏导致细菌BA代谢异常，从而取消BA诱导的免疫 SI中的公差。在这项提案中，我们提供了支持粘膜抗体缺乏结果的证据 在与SI肠病发展相关的异常炎性免疫反应中； 可能是由于细菌胆盐水解酶(BSH)活性升高而导致BA吸收不良(BAM)。 我们还发现，BSH消融或口服BA补充可以减轻BAM并抑制炎症 疾病。具体目标#1的目标是定义体液免疫如何影响BA动态平衡，以及 这如何协调在SI中建立耐受性免疫表型。几种互补模型 将被用来解决这一根本问题，并将结合先进的超纯技术 液-质联用(UPLC-MS)综合表征BA池组成， 并配对高参数流式细胞术和单细胞RNA测序以表征SI驻留免疫 细胞表型。具体目标#2的目标是演示粘膜抗体缺乏如何影响 驻留在SI上的微生物群落的组成和BA代谢能力。几部小说和 互补微生物定植模型、采用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的目标是测试两种候选方法的有效性 减轻炎症性肠病，包括口服BA补充剂或药物击倒 细菌促性腺激素活性。这项研究的创新之处包括首次分析了体液免疫的作用 在调节BA代谢中的作用，综合评价黏膜中IgA和IgM抗体的作用 反应在SI动态平衡中发挥作用，描述了一种新的生物失调驱动疾病的机制， 以及BSH消融和口服BA补充在耐受性重新编程中所起作用的特征 硅居留的免疫细胞在慢性疾病中的设置。Beyond，CVID，这项工作的结果与 人类的其他SI肠病包括克罗恩病、乳糜泻和热带主干。

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.