A Transgenic Model for B Cell Tolerance and Autoimmunity

描述(由申请人提供)：这项申请的长期目标是了解如何在健康个体中阻止自身反应性B细胞反应，以及它们如何在自身免疫性疾病中启动和维持。具体地说，研究了产生抗dsDNA抗体(Abs)的B细胞。这些抗体具有很高的临床意义；它们是自身免疫性疾病系统性红斑狼疮(SLE)的诊断标准之一，并参与了组织病理学的调节。该方法是利用仅含重链的TG(VH3H9)与内源性轻链配对来建立转基因(TG)模型，以产生抗DNA和非DNA抗体。在这里，抗dsDNA B细胞的发展可以在非自身免疫和倾向于自身免疫的背景下的不同B细胞谱系的背景下进行跟踪。采用这一策略，在BALB/c小鼠的血清中检测不到抗dsDNA抗体，但自身反应性B细胞持续存在于骨髓和外周，其表型表明抗原介导的发育停滞。相比之下，在自身免疫的动物中，它们是成熟的，在10周大的时候，可以在血清中检测到自身抗体。这种竞争性更新的特定目的是比较和对比来自非自身免疫和自身免疫小鼠的抗dsDNA B细胞的分化和激活潜力。信号强度对B细胞分化途径的影响将使用低亲和力的NAIVE、TH1和TH2效应器进行研究。旁观者T细胞激活影响抗dsDNA B细胞命运的能力将被探索。在证明了T调节细胞可以抑制T细胞帮助体内产生自身抗体的能力后，这种抑制背后的机制将被研究。T非依赖性刺激后抗dsDNA B细胞的激活和分化程度也将在体外和体内进行评估。具体地说，将研究暴露于TLR4和TLR9配体的B细胞的功能能力。希望通过更好地了解自身反应性B细胞的激活阈值，以及这种激活所导致的分化途径，将开发出更合理的治疗自身免疫性疾病的策略。

DESCRIPTION (provided by applicant): The long-term goal of this application has been to understand how autoreactive B cell responses are prevented in healthy individuals and how they are initiated and sustained in autoimmune disease. Specifically, B cells that produce anti-dsDNA antibodies (Abs) are studied. These Abs are highly significant clinically; they are one of the diagnostic criteria of the autoimmune disease Systemic Lupus Erythematosus (SLE), and they have been implicated in mediating tissue pathology. The approach has been to develop a transgenic (Tg) model using a heavy chain-only Tg (VH3H9) that can pair with endogenous light chains to generate both anti-DNA and non-DNA Abs. Here, the development of anti-dsDNA B cells can be tracked in the context of a diverse B cell repertoire in non-autoimmune and autoimmune-prone backgrounds. Taking this strategy, anti-dsDNA Abs are undetectable in the serum of BALB/c mice, yet the autoreactive B cells persist in the bone marrow and periphery with a phenotype indicative of antigen-mediated developmental arrest. In contrast, in autoimmune animals they are mature and by ten weeks of age autoAbs are detectable in the serum. Specific aims of this competitive renewal are to compare and contrast the differentiation and activation potential of anti-dsDNA B cells from non-autoimmune and autoimmune mice. The impact of signal strength on B cell differentiation pathways will be investigated using low avidity naive, TH1 and TH2 effectors. The ability of bystander T cell activation to influence anti-dsDNA B cell fate will be explored. Having demonstrated that T regulatory cells can suppress the ability of T cell help to drive autoAb production in vivo, the mechanism behind this suppression will be investigated. The extent of anti-dsDNA B cell activation and differentiation following T-independent stimulation will also be assessed both in vitro and in vivo. Specifically, the functional capabilities of B cells exposed to TLR4 and TLR9 ligands will be investigated. It is hoped that through a better understanding of autoreactive B cell activation thresholds, and the differentiation pathways that ensue as a consequence of this activation, that more rational therapeutic strategies for treating autoimmune diseases will be developed.