Analysis of Human B Cell Tolerance in Humanized Mice

描述(由申请人提供)：自身免疫性疾病可以在耐受过程中的缺陷上发展，这是一个消除和控制自我反应淋巴细胞的过程。以特异性抗体耗尽B细胞为目标的新型实验疗法强调了B淋巴细胞在自身免疫发病机制中的重要作用。然而，我们对人类B细胞耐受和B细胞选择过程的大部分知识来自于对小鼠免疫系统的研究，特别是对免疫球蛋白转基因小鼠的免疫系统的研究，因为在这些系统中，我们可以在有或没有自身抗原的情况下跟踪自身抗原特异性B细胞的发育。控制自身反应性B细胞的机制对自身免疫性疾病的病因学有一定的意义，到目前为止，大多数对自身免疫性疾病患者的研究都无法重建最初导致疾病的原始缺陷。这些研究揭示了研究人员在分析健康人和患病人的免疫耐受过程方面的方法学上的差距，并指出建立一个体内系统来机械地描述人类B细胞如何经历耐受将是有用的。重要的是，这样的系统还将使我们能够在未来确定自身免疫性疾病患者是否在特定的耐受机制中表现出缺陷，并测试可能的治疗方法来预防和/或纠正此类缺陷的病理表现。过去，抗免疫球蛋白抗体治疗一直被用于小鼠和其他动物，作为一种测试B细胞在抗原受体连接后是否经历耐受的方法。最近，表达抗原受体恒定区超抗原的转基因小鼠被用来了解多克隆免疫系统中正常B细胞如何获得耐受。此外，最近在产生人/鼠嵌合体(人源化小鼠)的方法学上取得了相当令人印象深刻的进展，在这些嵌合体中，人类造血干细胞重建了严重的联合免疫缺陷小鼠。这一系统为包括人类B细胞在内的人类免疫系统的更详细研究带来了巨大的希望。在这里，我们提出了利用人源化小鼠来研究B细胞发育的可行性。此外，我们建议将抗免疫球蛋白治疗和超抗原转基因技术与人/鼠嵌合体方法学相结合，建立一种新的系统来分析体内人类B细胞的中枢和外周免疫耐受。一旦这个新的系统被完全开发和表征，我们的目标是在未来的研究中确定来自健康和疾病个体的人类B细胞的耐受机制。 与公共卫生相关的系统性自身免疫性疾病，如红斑狼疮和类风湿性关节炎，是由B细胞和其他血细胞类型缺陷引起的复杂疾病，继续导致显著的发病率和死亡率。尽管对这些疾病已经有了大量的了解，但要充分了解这些疾病的病因和发病机制，以及开发新的和更有针对性的治疗方法，仍有大量的工作要做。我们的研究旨在开发和表征新的研究系统，这些系统可能有助于我们在机制水平上了解在健康和疾病个体中管理B细胞选择和调节的过程。这些新系统还将适用于在患者细胞上测试新的潜在疗法。

DESCRIPTION (provided by applicant): Autoimmune diseases can develop upon defects in the process of tolerance, a process that eliminates and control self-reactive lymphocytes. Novel experimental therapies that aim at depleting B cells with specific antibodies have emphasized the important role that B lymphocytes play in the pathogenesis of autoimmunity. However, most of our knowledge of the process of B cell tolerance and B cell selection in humans originates from studies of the mouse immune system and, in particular, of the immune system of immunoglobulin transgenic mice, because in these systems we can follow the development of self-antigen-specific B cells in the presence or absence of self-antigen. Which mechanisms control autoreactive human B cells has implication on the etiology of autoimmune diseases and, so far, most studies of autoimmune patients were unable to reconstruct the primary defects that have originally led to illness. These studies reveal gaps in the methodology available to investigators for the analysis of the immune tolerance process in healthy and diseased human individuals, and that it would be useful to have an in vivo system in which to characterize mechanistically how human B cells undergo tolerance. Importantly, such system would also allow us in the future to determine whether patients with autoimmune diseases manifest defects in specific tolerance mechanisms and to test possible therapies to prevent and/or correct the pathological manifestations of such defects. In the past, anti-immunoglobulin antibody treatment has been used in mice and other animals as a way to test whether B cells undergo tolerance upon antigen receptor ligation. Recently, transgenic mice expressing superantigens reactive to antigen receptor constant regions have been used to understand how tolerance is attained in normal B cells of polyclonal immune systems. Moreover, there has been quite impressive recent progress in the methodology to generate human/mouse chimeras (humanized mice) in which human hematopoietic stem cells reconstitute severe combined immunodeficient mice. This system holds tremendous promises for more detailed studies of the human immune system, including human B cells. Here we propose to characterize the feasibility of using humanized mice for the study of B cell development. Furthermore, we propose to combine the anti-immunoglobulin treatment and the superantigen transgenic technology with the human/mouse chimera methodology to generate a novel system to analyze human B cell central and peripheral tolerance in vivo. Once this novel system has been fully developed and characterized, we aim in future studies to determine the mechanisms of tolerance of human B cells from healthy and diseased individuals. PUBLIC HEALTH RELEVANCE Systemic autoimmune diseases such as lupus erythematosus and rheumatoid arthritis are complex disorders caused by defects in B and other blood cell types and that continue to cause significant morbidity and mortality. Although significant knowledge on these conditions has been achieved, substantial work remains to be done to fully understand the etiology and pathogenesis of these diseases and that will allow the development of novel and more targeted therapeutics. Our studies aim at developing and characterize novel research systems that may help us to understand at the mechanistic level the process that governs selection and regulation of B cells in healthy and diseased individuals. These novel systems will also be amenable for testing novel potential therapeutics on patient cells.