Tolerance in Polyclonal and Oligoclonal Immune Systems

描述（由申请人提供）：B细胞是自身免疫的重要致病成分，但我们目前对这些疾病中致病B细胞表型的了解有限。虽然大多数B细胞仅表达一种类型的抗体并且对一种抗原具有特异性，但是共表达两种不同抗体（即，双反应性B细胞）存在于小鼠中并且存在于人类中。我们的目标是了解双重反应性B细胞是否代表自身免疫中的相关B细胞亚群，并描述其生物学特征。我们的新发现表明，自身免疫小鼠比非自身免疫小鼠更频繁地产生双反应性B细胞。这些细胞中的大多数与自身抗原反应，并且它们在自身免疫小鼠的抗原活化的B细胞亚群中高度富集。此外，我们已经确定了一个分子途径，驱动非自身反应性未成熟B细胞分化为过渡和成熟B细胞，我们建议，也用于产生共表达自身反应性和非自身反应性抗体的B细胞。 在上一个资助周期中，我们通过生成我们新假设所依据的数据，并通过创建突变小鼠和方法来跟踪自身免疫和非自身免疫小鼠中双反应性B细胞的开发和选择，为拟议的研究奠定了基础。因此，我们认为，我们有独特的条件进行拟议的研究。 我们的假设是，双反应性B细胞逃避中枢和外周B细胞耐受机制，成为自身免疫性疾病的重要组成部分。该研究的目的是加深我们对小鼠双反应性B细胞与自身免疫之间关系的理解。我们将研究导致自身免疫易感小鼠中双重反应性B细胞产生、选择和富集增加的机制，以及这些B细胞是否有助于自身免疫的发展，或者是一种诊断标记物。我们还将通过检查具有自身免疫性的人类中双反应性B细胞的流行率来翻译我们的小鼠研究。 为了实现我们的目标，我们将开发以下具体目标：1）确定Ras和/或紧张性BCR信号传导的激活是否抑制自身反应性未成熟B细胞的负选择和促进正选择; 2）建立驱动自身免疫小鼠中双B细胞的增加的激活和正选择的B细胞外部信号; 3）确定双反应性B细胞是否有助于小鼠中的自身免疫，以及是否在自身免疫患者中富集。 提出的研究将建立双反应性B细胞作为自身免疫中的诊断和/或致病性B细胞亚群，并且将对开发鉴定和靶向这些B细胞同时保留抗感染的那些的方法具有价值。总之，这些研究对于理解B细胞介导的自身免疫发展机制和发现治疗干预的新靶点是重要的。

DESCRIPTION (provided by applicant): B cells are an important pathogenic component of autoimmunity, but our current knowledge of the phenotype of pathogenic B cells in these diseases is limited. While most B cells express only one type of antibody and are specific for one antigen, rare B cells co-expressing two different antibodies (i.e., dual-reactive B cells) exis in mice and are present in humans. Our goal is to understand whether dual-reactive B cells represent a relevant B cell subset in autoimmunity and to characterize their biology. Our novel findings demonstrate that autoimmune mice generate dual-reactive B cells more frequently than nonautoimmune mice. The majority of these cells react with self-antigens and they are highly enriched in the antigen-activated B cell subsets of autoimmune mice. Furthermore, we have identified a molecular pathway that drive the differentiation of nonautoreactive immature B cells into transitional and mature B cells and that, we propose, is also used for the generation of B cells that co-express autoreactive and nonautoreactive antibodies. In the previous grant cycle we laid the foundation for the proposed research by generating the data on which we base our new hypotheses and by creating the mutant mice and methodologies with which to follow development and selection of dual-reactive B cells in autoimmune and nonautoimmune mice. We believe, therefore, that we are uniquely poised to carry out the proposed studies. Our hypothesis is that dual-reactive B cells evade mechanisms of central and peripheral B cell tolerance to become an important component of autoimmune diseases. The goal of the proposed research is to deepen our understanding of the relationship between dual-reactive B cells and autoimmunity in mice. We will investigate the mechanisms that cause increased generation, selection and enrichment of dual-reactive B cells in autoimmune-prone mice and whether these B cells contribute to the development of autoimmunity or are rather a diagnostic marker. We will also translate our mouse studies by examining the prevalence of dual-reactive B cells in humans with autoimmunity. To achieve our goals we will develop the following specific aims: 1) to determine whether activation of Ras and/or of tonic BCR signaling inhibits negative selection and promotes positive selection of autoreactive immature B cells; 2) to establish the B cell-extrinsic signals that drive the increased activation and positive selection o dual-¿ B cells in autoimmune mice; 3) to determine whether dual-reactive B cells contribute to autoimmunity in mice and are enriched in autoimmune patients. The studies proposed will establish dual-reactive B cells as a diagnostic and/or pathogenic B cell subset in autoimmunity and will be of value for the development of methods that identify and target these B cells while preserving those that fight infections. Overall, these studies are important for understanding B cell-mediated mechanisms of autoimmune development and to uncover novel targets for therapeutic intervention.