The role of complement citrullination in RA pathogenesis

项目总结/摘要 理解驱动对自身抗原的免疫应答的机制是高度优先的。在 在类风湿性关节炎（RA）中，蛋白质瓜氨酸是免疫系统的主要靶标。重要数据 提示抗瓜氨酸化蛋白免疫应答参与RA发病机制，最近的证据表明 增强瓜氨酸的机制与最严重的疾病结果有关。虽然不同 虽然我们的研究结果表明，瓜氨酸可能是促进类风湿关节炎的一种机制，但我们发表的初步数据表明， 和补体系统是相互作用的途径， 产生和免疫介导的损害在一个相当大的子集的RA患者。因此，我们发现， 补体介导的膜溶解是RA关节中瓜氨酸蛋白的有效诱导物， 该过程与补体系统的关键调节成分瓜氨酸有关 （补体因子H（CFH）和C3），增强补体激活。之前的研究发现， 抗体在RA中普遍存在进一步强调了CFH在这种疾病中的重要性，增加了额外的 RA中补体失调的机制。总之，我们认为瓜氨酸诱导的 补体失调和抗CFH抗体是传播损伤和瓜氨酸的关键放大器 在RA关节活动。我们将在三个具体目标中检验这个假设。在目标1中，我们将使用质量 光谱分析和生化测定，以确定瓜氨酸对CFH的结构和功能影响， C3，以及这些修饰的蛋白质对诱导末端补体复合物的作用， 瓜氨酸化C3 dg介导的中性粒细胞高瓜氨酸血症和B细胞活化。目标2将使用多个 反应监测（MRM），以定量RA和其他关节炎患者滑液中的瓜氨酸化CFH和C3 以确定它们与关节中补体沉积和溶解活性的关联。目标3将决定 通过定义抗CFH抗体的患病率， 在RA中的临床意义，它们与补体激活的关系，以及它们对CFH功能的影响。 这些研究将定义与维持健康相关的疾病放大的新的相互作用机制。 炎症和加重类风湿关节的损伤。此外，研究表明，这些 在RA中，这些通路在体内是活跃的，从而鉴定用于精确治疗干预的标记物和亚组。

PROJECT SUMMARY/ABSTRACT Understanding the mechanisms which drive immune responses to autoantigens is of high priority. In rheumatoid arthritis (RA), protein citrullination is a major target of the immune system. Significant data implicates the anti-citrullinated protein immune response in RA pathogenesis, with recent evidence suggesting that mechanisms which enhance citrullination are associated with the worst disease outcome. While different mechanisms likely promote citrullination in RA, our published and preliminary data suggest that citrullination and the complement system are interacting pathways that amplify each other to enhance autoantigen production and immune-mediated damage in a sizable subset of RA patients. Thus, we have found that cellular membranolysis mediated by complement is a potent inducer of protein citrullination in the RA joint, and that this process is associated with citrullination of critical regulatory components of the complement system (complement factor H (CFH), and C3), enhancing complement activation. The previous finding that anti-CFH antibodies are prevalent in RA further highlights the importance of CFH in this disease, adding an extra mechanism that may dysregulate complement in RA. Taken together, we propose that citrullination-induced complement dysregulation and anti-CFH antibodies are key amplifiers that propagate damage and citrullination activity in the RA joint. We will examine this hypothesis in 3 Specific Aims. In Aim 1, we will use mass spectrometry and biochemical assays to define the structural and functional effects of citrullination on CFH and C3, as well as the effect of these modified proteins on the induction of the terminal complement complex, neutrophil hypercitrullination and B cell activation mediated by citrullinated C3dg. Aim 2 will use multiple reaction monitoring (MRM) to quantify citrullinated CFH and C3 in synovial fluid from RA and other arthritides to define their association with complement deposition and lytic activity in the joint. Aim 3 will determine whether anti-CFH antibodies participate in the dysregulation of complement in RA by defining their prevalence and clinical significance in RA, their association with complement activation, and their effect on CFH function. These studies will define novel interacting mechanisms of disease amplification relevant to sustain inflammation and aggravate damage in the rheumatoid joint. Furthermore, the studies will show that these pathways are active in vivo in RA, identifying markers and subgroups for precise therapeutic intervention.