B Cell Development Defects in Murine Lupus

描述（由申请人提供）：本提案的目的是更好地了解自身反应性B细胞被激活、分化为抗原产生细胞并通过激活自身反应性T细胞参与自身免疫应答的机制。我们将使用NZM 2410衍生的B6.NZMSle1/Sle 2/Sle 3狼疮易感菌株（B6.TC），由于其简化的遗传学（仅占NZM 2410基因组的约6%），该菌株构成了分析狼疮发病机制的免疫缺陷的理想模型。这使得B6和B6.TC之间的共培养和过继转移实验能够在真正的遗传控制背景下测试单细胞区室的贡献，这在其他狼疮实验模型中尚未实现。我们将使用免疫球蛋白HC转基因、类风湿因子（RF）AM 14、抗DNA 56 R和抗磷酸胆碱（PC）M167作为对照，以追踪B6. TC模型中自身反应性B细胞的命运。我们对AM 14模型的主要关注源于其作为抗核自身反应性的广义模型的新兴意义，其中自身抗原的存在可以被控制。为了实现这些目标，我们有两个具体目标：1。确定边缘区B细胞对B6.TC模型中自身免疫的贡献。体外和体内实验将确定B6. TC B细胞被选择至MZ亚群并参与自身免疫病理学的机制，并将确定MZ B细胞滤泡排斥破坏与自身抗体产生之间是否存在因果关系。2.确定B6.TC模型中RF AM 14 B细胞耐受性丧失的功能机制。B6.TC RF AM 14 B细胞被激活并通过与Fas缺陷型菌株中所述不同的机制分化为抗体产生细胞，包括多克隆激活的更大作用。这些机制的详细分析将利用我们的同源系统，系统地定义沿着整个B细胞发育过程中的各种细胞室的作用。总的来说，这些结果将提供一个更好的了解如何自身反应性B细胞的发展和促进自身免疫发病机制，也应该提供策略，以更好地针对这些细胞。 公共卫生相关性：B细胞耗竭是自身免疫性疾病（包括狼疮）最有前途的治疗策略之一。本项目拟通过自发性狼疮小鼠模型，研究B细胞参与疾病过程的机制。我们建议集中在两个主题：1）一个专门的B细胞亚群，称为边缘区B细胞，如何有助于自身免疫，和2）表征机制负责B细胞失去对自身的耐受性。这些研究的结果将提供对自身反应性B细胞的定义特征的更好理解，并将有助于针对这些自身反应性B细胞的靶向治疗。

DESCRIPTION (provided by applicant): The goal of this proposal is to better understand the mechanisms by which autoreactive B cells get activated, differentiate into antigen producing cells, and participate into the autoimmune response by activating autoreactive T cells. We will use the NZM2410-derived B6.NZMSle1/Sle2/Sle3 lupus-prone strain (B6.TC), which constitutes an ideal model to analyze the immune defects responsible for lupus pathogenesis because of its simplified genetics (only ~ 6% of the NZM2410 genome). This allows co-cultures and adoptive transfer experiments between B6 and B6.TC to test the contribution of a single cell compartment in the context of a true genetic control, which has not been achieved in other lupus experimental models. We will use immunoglobulin HC transgenes, rheumatoid factor (RF) AM14, anti-DNA 56R, and anti-phosphorycholine (PC) M167 as a control, to track the fate of autoreactive B cells in the B6.TC model. Our primary focus on the AM14 model stems from its emerging significance as a generalized model for anti-nuclear autoreactivity in which the presence of the autoantigen can be controlled. To achieve these goals, we have two specific aims: 1. To define the contribution of the marginal zone B cells to autoimmunity in the B6.TC model. In vitro and in vivo experiments will define the mechanisms by which B6.TC B cells are selected to the MZ subset and participate in autoimmune pathology, and will establish whether there is a causal relationship between breach in MZB cell follicular exclusion and production of autoantibodies. 2. To define the functional mechanisms responsible for the loss of tolerance of RF AM14 B cells in the B6.TC model. B6.TC RF AM14 B cells are activated and differentiate into antibody producing cells by mechanisms that differ to what has been described in Fas-deficient strains, including a much greater role for polyclonal activation. A detailed analysis of these mechanisms will take advantage of our congenic system to systematically define the role of various cell compartments along the entire B cell developmental process. Overall, these results will provide a better understanding of how autoreactive B cells develop and contribute to autoimmune pathogenesis, and should also provide strategies to better target these cells. PUBLIC HEALTH RELEVANCE: B-cell depletion is the one of the most promising therapeutic strategies in autoimmune diseases, including lupus. This project proposes to investigate the mechanisms by which B cells contribute to the disease process by using a mouse model that spontaneously develops lupus. We propose to focus on two topics: 1) how a specialized subset of B cells, called marginal zone B cells, contributes to autoimmunity, and 2) to characterize the mechanism responsible for B cells to lose to tolerance to self. The results from these studies will provide a better understanding of the defining features of autoreactive B cells and will help to target therapies toward these autoreactive B cells.