Regulation and Function of Immunoglobulin D in Mucosal Immune Defense

描述（由申请人提供）：本申请由RFA授权用于U01，这将使我们能够与其他杰出的粘膜免疫学家协同合作，共同发现和利用IgD（一种进化上保守但神秘的抗体）被忽视的粘膜保护功能。人上呼吸道粘膜含有丰富的产生IgD的B细胞，其将IgD释放到鼻、泪管、唾液、乳房和支气管分泌物中。近50年来对IgD的大量临床和免疫学观察表明，IgD在呼吸道粘膜免疫防御中具有重要作用。该项目的广泛、长期目标是阐明IgD产生的调节以及IgD在呼吸道免疫中的机制和功能，以开发利用IgD功能对抗呼吸道感染的疫苗和治疗与IgD过度产生相关的免疫病理学的疗法。本研究假设来自上呼吸道粘膜的B细胞经历由维生素D3控制的IgD产生和多样化，并且产生的IgD通过与肝素、嗜酸性粒细胞阳离子蛋白和炎性小体相互作用激活局部和全身先天性免疫细胞如嗜碱性粒细胞和肥大细胞来对抗呼吸道病原体并有助于粘膜免疫。提出了三个目标。目的1：阐明呼吸道粘膜中IgD类转换和产生的调节。目的2：研究粘膜IgD的反应性、克隆多样性、进化和保护功能。目的3：探讨IgD激活粘膜和全身免疫应答的机制。这项研究将利用来自健康供体和高lgD综合征（一种自身炎症性周期性发热综合征）患者的细胞和组织作为疾病模型。将通过生物化学、分子和细胞生物学技术研究维生素D3对IgD产生的调节以及IgD触发免疫激活的机制。将通过单B细胞分选、克隆和表达、高通量下一代测序和基于体外细胞培养的方法来研究呼吸道病原体暴露后和接种后粘膜和全身IgD应答的反应性和保护功能。 相关性：该项目将建立免疫接种后IgD反应的临床相关信息，并导致可用于临床对抗呼吸道感染的保护性IgD克隆的分离。它还将支持在治疗免疫病理学中使用维生素D修饰方案，并建立针对呼吸道病原体的更有效的疫苗接种策略，积极促进IgD反应。

DESCRIPTION (provided by applicant): This application is mandated by the RFA for U01, which will allow us to synergize with other outstanding mucosal immunologists and cooperatively uncover and harness the neglected mucosal protective functions of IgD, an evolutionarily conserved yet mysterious class of antibody. Human upper respiratory mucosa contains abundant IgD-producing B cells that release IgD into nasal, lachrymal, salivary, mammary and bronchial secretions. Numerous clinical and immunological observations of IgD in the past 50 years strongly suggest that IgD has important functions in respiratory mucosal immune defense. The broad, long-term objectives of this project are to elucidate the regulation of IgD production as well as the mechanism and function of IgD in respiratory immunity in order to develop vaccines that harness the functions of IgD to combat respiratory infections and therapies to treat immunopathologies associated with IgD hyperproduction. This study hypothesizes that B cells from upper respiratory mucosa undergo IgD production and diversification controlled by vitamin D3 and that IgD produced reacts against respiratory pathogens and contributes to mucosal immunity by activating local and systemic innate immune cells such as basophils and mast cells through interaction with heparin, eosinophil cationic protein and inflammasomes. Three aims are proposed. Aim 1: To elucidate the regulation of IgD class switching and production in the respiratory mucosa. Aim 2: To determine the reactivity, clonal diversity, evolution and protective function of mucosal IgD. Aim 3: To dissect the mechanisms by which IgD activates mucosal and systemic immune responses. This study will take advantage of cells and tissues from healthy donors and patients with hyper-lgD syndrome, an autoinflammatory periodic fever syndrome, as a disease model. The regulation of IgD production by vitamin D3 and the mechanism by which IgD triggers immune activation will be investigated by biochemical, molecular and cellular biology techniques. The reactivity and protective functions of mucosal and systemic IgD responses upon respiratory pathogen exposure and after vaccination will by studied by single B cell sorting, cloning and expression, high-throughput next-generation sequencing and in vitro cell culture-based methods. RELEVANCE: This project will establish clinically relevant information on IgD responses after vaccination and lead to the isolation of protective IgD clones that may be used clinically to combat respiratory infections. It will also support the use of vitamin D modifying regimens in treating immunopathologies and establish that more effective vaccination strategies against respiratory pathogens should actively boost IgD responses.