Loss of B cell tolerance in rheumatoid arthritis

描述（由申请人提供）：自身抗体是包括类风湿性关节炎（RA）在内的大多数自身免疫性疾病的特征，并且在临床疾病发病前多年出现在血清中，提示RA中B细胞耐受性的早期中断。B细胞在RA中的重要作用已被成功治疗RA患者的抗cd20单克隆抗体所支持，该抗体可消除B细胞。RA中自身反应性B细胞和自身抗体产生的潜在机制尚不清楚。我们最近通过检测从单个新迁移B细胞和成熟幼稚B细胞克隆的重组抗体的特异性，分析了未经治疗的活动性RA患者的B细胞耐受性。RA患者表现出有缺陷的中央和外周B细胞耐受检查点，导致自身反应性成熟幼稚B细胞的积累，可能导致RA发病。此外，大约一半的RA患者出现新的移入性B细胞，其受体编辑存在缺陷，这是通常确保B细胞耐受的3种机制之一。另一半患者显示新的迁移B细胞具有异常长的（11个或更多氨基酸）互补决定区3 (cdrs)，与自身反应性相关，并在RA滑膜中富集。拟议研究的长期目标是确定在健康人群中调节B细胞耐受性但在RA患者中存在缺陷的机制。目前的假设是RA B细胞存在内在的BCR信号缺陷，影响了发育中的自身反应性B细胞的正确反选择，导致外周自身反应性B细胞异常募集和激活滑膜。该项目的第一个目标将包括通过比较来自对照和RA B细胞亚群的微阵列基因表达谱（无论是否由其BCR触发）来表征RA B细胞耐受检查点早期缺陷的分子基础，这些基因表达谱可能揭示RA患者不同亚群的特定BCR信号缺陷。该项目的第二部分将确定替代B细胞耐受机制，例如可以替代人类有缺陷的受体编辑的能量。该项目的第三部分将分析RA患者滑膜中B细胞耐受性是如何被破坏的。这些研究对于了解自身免疫性疾病患者如何产生攻击身体的抗体具有重要意义，并可能为开发新药物提供线索。

DESCRIPTION (provided by applicant): Autoantibodies are a characteristic of most autoimmune diseases including rheumatoid arthritis (RA) and appear in the serum many years before the onset of clinical disease, suggesting an early break in B cell tolerance in RA. An important role for B cells in RA has been supported by successful treatment of RA patients with anti-CD20 monoclonal antibodies that eliminate B cells. The underlying mechanisms that account for autoreactive B cell and autoantibody production in RA are poorly defined. We recently analyzed B cell tolerance in untreated active RA patients by testing the specificity of recombinant antibodies cloned from single new emigrant and mature naive B cells. RA patients exhibit defective central and peripheral B cell tolerance checkpoints that result in the accumulation of serf-reactive mature naive B cells, likely contributing to RA pathogenesis. In addition, about half of RA patients showed new emigrant B cells with defective receptor editing, one of the 3 mechanisms that normally ensure B cell tolerance. The other half of the patients displayed new emigrant B cells with unusually long (11 or more amino acids) complementarity determining region 3 (CDRSs) associated to self-reactivity and found enriched in the RA synovium. The long range goal of the proposed research is to determine the mechanisms that regulate B cell tolerance in healthy humans but are defective in RA patients. The working hypothesis is that RA B cells suffer from intrinsic BCR signaling defects that impinge on the proper counterselection of developing autoreactive B cells, and result in the abnormal recruitment and activation of peripheral self-reactive B cells into the synovium. The first aim of the project will consist of characterizing the molecular basis for early defects in B cell tolerance checkpoints in RA by comparing microarray gene expression profiles from control and RA B cell subpopulations (whether or not triggered by their BCR) that may reveal specific BCR signaling defects for the different subgroups of RA patients. The second part of the project will identify alternative B cell tolerance mechanisms such as anergy that can substitute for defective receptor editing in humans. The third part of the project will analyze how B cell tolerance is broken in the synovium of RA patients. These studies have significant implications for understanding how people with autoimmune diseases produce antibodies that attack their body and may provide clues for development of new medications.