Immune Modulating HLA-Coded Ligands in Rheumatoid Arthritis

摘要 共有表位(SE)是严重类风湿性关节炎(RA)的唯一最重要的危险因素，但其 其作用机制尚不完全清楚。在这个R01项目的01-05预算年度，我们确定了 SE作为信号转导配体与细胞表面明确的结合部位特异性地相互作用 钙网蛋白(CRT)并激活细胞内信号事件，导致Th17极化和破骨细胞 激活。当给予胶原性关节炎小鼠时，合成的SE配体增强了 侵蚀性节理破坏的严重性。此外，根据SE-CRT的结构和功能特点， 通过相互作用，我们已经用CRT结合的小分子有效地治疗了这一途径 抑制关节形成途径，从而改善小鼠实验性关节炎。 根据本项目本轮筹资周期取得的初步成果，我们将在06-10年度开展 实验将促进我们对分子机制和功能结果的理解 SE激活的途径。此外，我们还将阐明保护性信号的信号和功能效应 我们最近发现的表位(PE)配体。这种配体似乎能中和SE途径，并可能 解释特定的人类白细胞抗原-DRB1之间存在已久但知之甚少的流行病学联系 等位基因与类风湿关节炎的防护 该项目的假说表明，在RA：A.促进疾病和保护疾病的人类白细胞抗原- DRB1等位基因编码不同的配体，传递相互的细胞激活和分化信号； SE途径激活蛋白质的瓜氨酸化作用。未来5年的研究计划将解决这一问题 假说的具体目的如下：1.描绘各自的信号通路激活 SE和PE配体及其在细胞分化中的功能作用；2.分析标志性的人类白细胞抗原- 用RNA-seq方法研究DRB1编码的配体激活转录本；3.研究其作用机制 最近发现的SE激活的蛋白瓜氨酸化途径，并确定其在体内的作用。 拟议研究的成功完成将阐明有关人类白细胞抗原疾病的基本问题 协会，为RA的发病机制和病因提供了重要的新见解，并为 设计新的治疗策略。

ABSTRACT The shared epitope (SE) is the single most significant risk factor for severe rheumatoid arthritis (RA), yet its mechanism of action is not completely understood. During budget years 01-05 of this R01 project, we identified the SE as a signal transduction ligand that specifically interacts with a well-defined binding site on cell surface calreticulin (CRT) and activates intracellular signaling events that lead to Th17 polarization and osteoclast activation. When administered to mice with collagen-induced arthritis, a synthetic SE ligand enhanced the severity of erosive joint destruction. Furthermore, based on structure-function characteristics of SE-CRT interaction, we have therapeutically targeted the pathway with CRT-binding small molecules that potently inhibited the arthritogenic pathway with resultant amelioration of experimental arthritis in mice. Based on preliminary results obtained in the current funding cycle of this project, in years 06 – 10 we will carry out experiments that will advance our understanding of the molecular mechanisms and functional outcomes of the SE-activated pathway. Additionally, we will elucidate the signaling and functional effects of a protective epitope (PE) ligand that we recently discovered. This ligand appears to counteract the SE pathway and may explain a long-established but poorly understood epidemiologic association between particular HLA-DRB1 alleles and protection against RA. The hypothesis of this project states that in RA: A. Disease-facilitating and disease-protective HLA- DRB1alleles code for distinct ligands, which transduce reciprocal cell activation and differentiation signals; B. The SE pathway activates protein citrullination. The research plan in the coming 5 years will address this hypothesis with the following specific aims: 1. To delineate the respective signaling pathways activated by the SE and PE ligands and determine their functional effects on cell differentiation; 2. To analyze signature HLA- DRB1-coded ligand-activated transcriptomes using an RNA-seq approach; 3. To characterize the mechanism of a recently discovered SE-activated protein citrullination pathway, and determine its in vivo effects. Successful completion of the proposed research will illuminate fundamental questions concerning HLA-disease association, provide important new insights into the pathogenesis and etiology of RA, and set the stage for designing novel therapeutic strategies.