B Cell Tolerance in Lupus

描述(申请人提供)：有大量证据表明，自身抗体(AutoAbbs)是通过体细胞超突变产生的，在系统性红斑狼疮(SLE)中，通过这一过程获得自我反应的B细胞的耐受性受到损害。尽管最近的研究对发生体细胞高突变(SHM)的生发中心(GC)反应的参与者和细胞动力学提供了相当大的见解，但在理解新产生的自身反应性B细胞维持耐受的机制方面进展甚微，这主要是因为缺乏合适的模型。我们最近与其他研究人员合作，使用了一种新型的32a-大自身抗原(Ag)转基因(TG)系统，表明Fas缺陷小鼠在审查对表面结合的Ag具有自身反应性的B细胞方面存在缺陷。然而，这个模型使用了一种人造银，其特征与SLE中声称的AutoAgs有很大不同。为了解决这些局限性，我们建立了一个新的B细胞受体TG模型，该模型将允许在经历类切换重组(CSR)/SHM的B细胞中用DNA结合受体替换无害的抗原受体，并试图发展这个模型并用它来研究正常和自身免疫小鼠SHM后的耐受机制。为此，我们提出了三个目标：1)建立FLEX-AutoAb模型系统；2)研究CSR/SHM后B细胞在非自身免疫小鼠中的耐受性；3)研究狼疮易感B6-Faslpr小鼠对CSR/SHM后B细胞的耐受性。这种新的方法有可能显著提高我们研究在外围获得自身反应性的B细胞的耐受性的能力，对这一过程产生新的和重要的见解，并显著推进这一与SLE和其他自身抗体介导的疾病高度相关的研究领域。 公共卫生相关性：B细胞对自身的缺陷耐受性被认为是系统性红斑狼疮(SLE)产生有害自身抗体的主要原因之一；然而，这一过程的许多方面仍然知之甚少，特别是抑制在体细胞高突变期间获得自我反应的B细胞的耐受机制。目前，没有一个现有的动物模型能够直接研究成熟的B细胞，这些细胞对SLE中通常靶向的自身抗原具有自身反应性。为了解决这个问题，我们建议使用一种新的方法来生成一个新的、更相关的模型，称为FLEX-AutoAb。

DESCRIPTION (provided by applicant): There is abundant evidence that autoantibodies (autoAbs) are generated through somatic hypermutation and that tolerance of B cells that acquire self-reactivity through this process is impaired in systemic lupus erythematosus (SLE). Although recent studies have provided considerable insights into the participants and cellular dynamics in germinal center (GC) reactions where somatic hypermutation (SHM) takes place, there has been little progress in understanding the mechanisms for maintaining tolerance of newly generated self- reactive B cells, largely because of the absence of an appropriate model. We, in collaboration with other investigators, have recently used a novel 32a-macroself antigen (Ag) transgenic (Tg) system to show that Fas- deficient mice are defective in censoring B cells that have acquired autoreactivity to a surface-bound Ag. This model, however, utilizes an artificial Ag with characteristics that differ substantially from the purported autoAgs in SLE. To address these limitations, we have formulated a new B cell receptor Tg model that will allow replacement of an innocuous antigen-receptor with a DNA-binding receptor in B cells undergoing class switch recombination (CSR)/SHM, and seek to develop this model and use it to investigate post-SHM tolerance mechanisms in normal and autoimmune mice. To accomplish this, three aims are proposed that will: 1) generate the FLEx-autoAb model system, 2) characterize tolerance of post-CSR/SHM B cells in non- autoimmune mice, and 3) characterize tolerance of post-CSR/SHM in lupus-prone B6-Faslpr mice. This novel approach has the potential for significantly improving our ability to study tolerance of B cells that acquire autoreactivity in the periphery, to generate new and important insights into this process, and to substantially advance this area of investigation, which is highly relevant to SLE and other autoAb-mediated diseases. PUBLIC HEALTH RELEVANCE: Defective tolerance of B cells to self is considered to be one of the major causes of systemic lupus erythematosus (SLE) responsible for the production of harmful autoantibodies; yet many aspects of this process remain poorly understood particularly tolerance mechanisms that keep in check B cells that acquire self-reactivity during somatic hypermutation. Currently none of the existing animal models are able to directly study mature B cells that acquire autoreactivity to self-antigens commonly targeted in SLE. To address this issue, we proposed to generate a new and more relevant model, called FLEx-autoAb, using a novel approach.