The role of complement citrullination in RA pathogenesis

项目摘要/摘要 了解驱动对自身抗原的免疫反应的机制是非常重要的。在……里面 类风湿关节炎(RA)，蛋白瓜氨酸化是免疫系统的主要靶点。重要数据 抗瓜氨酸蛋白免疫反应在类风湿关节炎发病机制中的作用，最近的证据表明 这种增强瓜氨酸化的机制与最糟糕的疾病结局有关。虽然不同 在RA中可能促进瓜氨酸化的机制，我们公布的和初步数据表明瓜氨酸化 和补体系统是相互放大以增强自身抗原的相互作用的途径 相当大一部分类风湿关节炎患者的产生和免疫介导的损伤。因此，我们发现细胞 补体介导的膜溶解是RA关节蛋白瓜氨酸化的有效诱导剂 这一过程与补体系统的关键调节成分的瓜氨酸化有关 (补体因子H(CFH)和补体C3)，增强补体激活。先前的研究发现，抗CFH 抗体在RA中的流行进一步强调了CFH在这种疾病中的重要性，增加了一个额外的 类风湿关节炎中补体调节失调的机制。综上所述，我们认为瓜氨酸化诱导 补体调节失调和抗CFH抗体是传播损伤和瓜氨酸化的关键放大因子 在RA关节的活动。我们将从三个具体目标来检验这一假设。在目标1中，我们将使用质量 光谱和生化分析以确定瓜氨酸化对CFH和CFH的结构和功能影响 C3，以及这些修饰蛋白对末端补体复合体诱导的影响， 瓜氨酸C3dG介导的中性粒细胞高瓜氨酸化和B细胞活化。AIM 2将使用多个 反应监测(MRM)定量检测RA和其他关节炎关节滑液中瓜氨酸化CFH和C3 以确定它们与补体沉积和关节中的溶解活性之间的关系。目标3将决定 抗CFH抗体是否参与类风湿关节炎补体调节失调 和RA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。 这些研究将定义与持续相关的疾病放大的新的相互作用机制 类风湿关节的炎症和加重损伤。此外，研究将表明，这些 在RA体内，通路是活跃的，识别用于精确治疗干预的标志物和亚组。

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.