A Novel Immune Stimulatory Ligand in Autoimmunity-Associated Angiogenesis

描述（由申请人提供）：“共享表位”（SE）-绝大多数类风湿性关节炎（RA）患者携带的HLA-DRB 1编码的5-氨基酸序列基序-与严重疾病相关。RA-SE关联的机制基础尚不清楚。在先前的研究中，该实验室已经证明SE作为信号转导配体激活其他细胞中的一氧化氮（NO）产生。SE信号由细胞表面钙网蛋白（CRT）转导，钙网蛋白是一种已知的先天免疫受体，以前与免疫调节、自身免疫和血管生成有关。为了更好地理解SE在RA中的致病作用，我们已经开始表征RA相关细胞中的SE信号事件。初步数据表明，在树突状细胞（DC）中，SE是调节性T（Treg）细胞的有效抑制剂和促血管生成、产生IL-17的T（Th 17）细胞的增强剂。在内皮细胞（EC）中，SE触发促血管生成因子IL-8、IL-6和单核细胞趋化蛋白-1（MCP-1）的产生。此外，发现CRT在RA患者的滑膜中过度瓜氨酸化，并且瓜氨酸化的CRT显示出对SE的显著更高的亲和力，并且比未修饰的蛋白质转导更有效的信号。因此，SE触发血管生成相关的功能事件，可以解释其在RA中的作用。本文提出的研究的主要目标是描述SE在血管生成中的作用，这是包括RA在内的几种自身免疫性疾病的关键病理机制。具体而言，我们建议：1.使用耐受性和胶原诱导的关节炎（CIA）的小鼠模型表征SE介导的Th 17极化的功能效应; 2.确定SE-CRT对血管生成和CIA实验小鼠模型EC活化的影响; 3.确定CRT瓜氨酸肽在小鼠EC中SE激活的促血管生成效应中的作用这些研究共同提供了一种新范式的检查，该范式为RA的几个重要机制方面提供了统一的解释。从长远来看，在这个项目中获得的新知识可以为设计新的治疗策略提供基础。

DESCRIPTION (provided by applicant): The "shared epitope" (SE) - a HLA-DRB1-encoded 5-amino acid sequence motif carried by the vast majority of rheumatoid arthritis (RA) patients - is associated with severe disease. The mechanistic basis of RA-SE association is unknown. In prior studies, this laboratory has demonstrated that the SE acts as a signal transduction ligand that activates nitric oxide (NO) production in other cells. SE signaling is transduced by cell surface calreticulin (CRT), a known innate immunity receptor previously implicated in immune regulation, autoimmunity and angiogenesis. To better understand the pathogenic role of the SE in RA, we have begun characterizing SE signaling events in RA-related cells. Preliminary data demonstrate that in dendritic cells (DCs) the SE is a potent inhibitor of regulatory T (Treg) cells and enhancer of pro-angiogenic, IL-17- producing T (Th17) cells. In endothelial cells (ECs), the SE triggers production of the pro-angiogenic factors, IL-8, IL-6 and monocyte chemotactic protein-1 (MCP-1). Additionally, it was found the CRT is over- citrullinated in the synovium of RA patients and citrullinated CRT showed markedly higher affinity to the SE and transduced much more potent signals than the unmodified protein. Thus, the SE triggers angiogenesis- relevant functional events that could account for its effect in RA. The main goal of the research proposed here is to characterize the effect of the SE in angiogenesis, a key pathgenetic mechanism in several autoimmune conditions, including RA. Specifically, we propose to: 1. Characterize the functional effect of SE-mediated Th17 polarization using mouse models of tolerance and collagen-induced arthritis (CIA); 2. Determine the effect of the SE-CRT on EC activation in experimental mouse models of angiogenesis and CIA; 3. Determine the role of CRT citrullination in SE-activated pro- angiogenic effect in mouse ECs Collectively, these studies offer an examination of a novel paradigm that provides a unifying explanation for several important mechanistic aspects of RA. In the long run, the new knowledge gained in this project could provide a basis for designing novel therapeutic strategies.