Role of B cells in pathogenesis of Collagen-induced Arthritis in Humanized Mice

描述（由申请人提供）： 已知类风湿性关节炎（RA）及其动物模型胶原诱导的关节炎（CIA）是T和B细胞依赖性疾病。HLA-DQ 8和DRB 1 *0401分子使人类和小鼠易于发展关节炎，而DQ 6和DRB 1 *0402提供保护。CIA易感HLA转基因小鼠产生类风湿因子和抗环瓜氨酸肽（CCP）抗体类似于患者。在B细胞敲除小鼠中缺乏CIA和低细胞应答表明，自身反应性B细胞除了产生抗体之外，还可能参与向T细胞呈递自身抗原。患者中B细胞耗竭后ACR反应标准的改善进一步强调了B细胞在关节炎中的作用。然而，B细胞在抗原呈递中的确切作用及其在转基因小鼠的敏感品系与抗性品系中的调节仍不清楚。B细胞功能受B细胞受体BCR以及其它B细胞特异性受体如BAFF-R调节。我们的假设是，携带RA易感HLA基因的转基因小鼠中的B细胞存在调节缺陷，这种缺陷通过B细胞受体发生，导致自身反应性B细胞的过度活跃和存活增加。雌性具有过度活跃的B细胞，其有助于自身抗体的形成和抗原向T细胞的呈递，导致雌性的发病率增加。我们的初步数据与这一观点一致。最近的研究表明，B细胞的反应是由TLR控制的。在这项研究中，我们将解决的机制，B细胞对胶原诱导的关节炎的发病机制，在转基因小鼠使用小鼠表达CIA敏感和耐HLA基因。在aim 1中，我们将明确CIA发病机制中对B细胞作为抗原呈递细胞的需求。在目标2中，我们将检验我们的假设，如果B细胞反应的过度活跃和遗传易感小鼠中的表位扩散导致致病性反应。此外，由于并非所有RA易感等位基因阳性的转基因小鼠都发生关节炎，因此将确定发生关节炎的小鼠与未发生关节炎的小鼠中B细胞活化状态的潜在差异。在目的3中，我们将在该模型中确定Toll样受体，特别是TLR 4对B细胞应答的控制。本文提出的这些转基因小鼠和实验应该提供B细胞背景下的发病机制，并缩小B细胞定向治疗的焦点。 公共卫生相关性：风湿性关节炎是一种致残性疾病，女性比男性更常见。B细胞产生类风湿因子和其他自身抗体。在这项研究中，我们将使用表达人类关节炎相关基因的小鼠来描述B细胞在类风湿性关节炎患者中的作用。这些人源化小鼠在病理学和性别偏倚方面模拟类风湿性关节炎。关节炎小鼠产生自身抗体，如类风湿因子和抗环瓜氨酸肽抗体，用于诊断类风湿关节炎。我们将确定B细胞是否可以呈递致病性抗原，以及关节炎易感小鼠中B细胞的调节是否存在缺陷。使用这种独特的模型获得的信息可能是有益的，在发展中的关节炎，特别是在妇女的预防性免疫干预。

DESCRIPTION (provided by applicant): Rheumatoid arthritis (RA) and its animal model collagen-induced arthritis (CIA) are known to be T and B cell dependent diseases. HLA-DQ8 and DRB1*0401 molecules render humans and mice susceptible to develop arthritis while DQ6 and DRB1*0402 provide protection. CIA susceptible HLA transgenic mice produce rheumatoid factor and anti-cyclic citrullinated peptide (CCP) antibodies similar to that in patients. Absence of CIA and low cellular responses in B cell knockout mice suggests that the autoreactive B cells, in addition to producing antibodies may also be involved in presenting auto antigens to T cells. Improvement in ACR response criteria after depletion of B cells in patients further underscores the role of B cells in arthritis. However, the exact role of B cells in antigen presentation and their regulation in susceptible versus resistant strains of transgenic mice remains unclear. B cell function is regulated by B cell receptor, BCR, as well as other B cell specific receptors like BAFF-R. Our hypothesis is that B cells in transgenic mice carrying RA susceptible HLA gene have a defect in regulation which occurs through B cell receptor leading to hyperactivity and increased survival of autoreactive B cells. Females have hyperactive B cells which contribute towards the development of autoantibodies and presentation of antigens to T cells leading to increased incidence in females. Our preliminary data is consistent with this notion. Recent studies have shown that B cell responses are controlled by TLRs. In this study we will address the mechanism by which B cells contribute towards pathogenesis of collagen-induced arthritis in transgenic mice using mice expressing both CIA-susceptible and resistant HLA genes. In aim1, we will define the requirement of B cells as antigen presenting cells in pathogenesis of CIA. In aim 2 we will test our hypothesis if hyperactivity of B cell responses and epitope spreading in genetically susceptible mice leads to pathogenic response. Also, since not all transgenic mice positive for RA susceptible allele develop arthritis, potential differences in B cell activation status in those that develop arthritis versus that do not will be determined. In aim 3, we will determine the control of B cell responses by Toll like receptors, especially, TLR4 in this model. These transgenic mice and experiments proposed here should provide a mechanism of pathogenesis in context of B cells and narrow the focus of B cell-directed therapy. PUBLIC HEALTH RELEVANCE: Rheumatoid arthritis is a disabling disease, affecting women more often than men. B cells produce rheumatoid factor and other autoantibodies. In this study we will use mice that express human arthritis associated genes to delineate the role of B cells in rheumatoid arthritis patients. These humanized mice mimic rheumatoid arthritis in pathology and sex-bias. Arthritic mice produce autoantibodies like rheumatoid factor and anti-cyclic citrullinated peptide antibodies that are used for diagnosis of rheumatoid arthritis. We will determine if B cells can present pathogenic antigen and if there is a defect in regulation of B cells in arthritis susceptible mice. The information gained using this unique model may be instructive in developing preventive immunointervention for ongoing arthritis especially in women.