Tracking Extracellular Vesicles Derived From B Cells in Autoimmunity

项目摘要 免疫复合物（IC）引起炎症反应，是系统性狼疮多器官损害的关键 红斑性狼疮（SLE）。尽管有明确的证据将IC与SLE的发病机制联系起来， 形式和影响IC在组织中定位和致病性的因素仍然难以捉摸。我们 初步研究表明，活化的B细胞分泌表达抗原的细胞外囊泡（EV）， 特异性表面IgG和结合抗原。此外，我们已经从狼疮易感小鼠中鉴定出了循环IgG + EV 结合核抗原，被中性粒细胞吸收，并定位于肾脏。最近对系统性红斑狼疮患者的研究 还鉴定了在其表面上共表达IgG和核抗原的循环EV， 整个血浆中抗核抗体滴度增加。基于这些数据，我们提出了一个新的假设， 由活化的B细胞释放的表达IgG的EV直接上调炎症途径（即，作为 IC），或间接地通过与先天免疫系统的各种细胞相互作用，这些细胞随后有助于免疫应答。 狼疮的发病机制我们将使用一种新的报告小鼠品系来测试这一假设，该小鼠品系允许在体内 对来源于类别转换IgG + B细胞的EV的追踪、分离和功能询问。因为利特尔是 了解了IC如何在体内形成以及它们如何在自身免疫中促进炎症免疫应答，我们 提出了一系列探索性实验来评估B细胞衍生的EV的固有生物物理性质， 以及B细胞衍生的EV对IC形成和对炎症反应的控制的作用。 健康和自身免疫性疾病状态下的先天免疫细胞（单核吞噬细胞;中性粒细胞）。我们将 使用尖端技术严格分析单个B细胞衍生的EV，并从分子上定义 产生表达IgG的EV的B细胞亚群。这些实验将提供一个重要的框架， 确定这种潜在的新型IC形成模式的功能和疾病相关功能障碍。我们长久以来- 长期目标是研究B细胞衍生的EV在介导细胞间通讯、调节有害细胞因子和细胞因子中的作用。 SLE中的宿主免疫反应，这可能提供新的治疗策略，以减少炎症和组织 损伤

PROJECT ABSTRACT Immune complexes (ICs) cause inflammation and are critical for the damage of multiple organs in systemic lupus erythematosus (SLE). Despite clear evidence linking ICs to the pathogenesis of SLE, identification of how ICs form and the factors that influence IC localization and pathogenicity in tissues has remained elusive. Our preliminary studies demonstrate that activated B cells secrete extracellular vesicles (EVs) that express antigen- specific surface IgG and bind antigen. Moreover, we have identified circulating IgG+ EVs from lupus-prone mice that bind nuclear antigens, are taken up by neutrophils, and localize to the kidney. Recent studies of SLE patients have also identified circulating EVs that co-express IgG and nuclear antigens on their surface which correlate with increased antinuclear antibody titers in whole plasma. Based on these data, we propose a novel hypothesis that IgG-expressing EVs released by activated B cells upregulate inflammatory pathways either directly (i.e., as an IC), or indirectly by interacting with a variety of cells of the innate immune system that then contribute to the pathogenesis of lupus. We will test this hypothesis using a novel reporter mouse strain that allows for the in vivo tracking, isolation, and functional interrogation of EVs derived from class-switched IgG+ B cells. Since little is known about how ICs form in vivo and how they promote inflammatory immune responses in autoimmunity, we propose a series of exploratory experiments to evaluate the intrinsic biophysical properties of B cell-derived EVs, and the effect of B cell-derived EVs on the formation of ICs and on the control of inflammatory responses of innate immune cells (mononuclear phagocytes; neutrophils) in healthy and autoimmune disease states. We will use cutting-edge technologies to rigorously analyze individual B cell-derived EVs and to molecularly define the B cell subsets that produce IgG-expressing EVs. These experiments will provide an important framework for determining the function and disease-related dysfunction of this potentially novel mode of IC formation. Our long- term goal is to investigate B cell-derived EVs in mediating intercellular communication, regulating deleterious host immune responses in SLE, which may provide new therapeutic strategies to reduce inflammation and tissue injury.