A Novel Immune Stimulatory Ligand in Autoimmunity-Associated Angiogenesis

描述（由申请人提供）：“共享表位”（SE）是绝大多数类风湿关节炎（RA）患者携带的hla - drb1编码的5个氨基酸序列基序，与严重疾病相关。RA-SE关联的机制基础尚不清楚。在之前的研究中，本实验室已经证明SE作为一种信号转导配体，在其他细胞中激活一氧化氮（NO）的产生。SE信号是由细胞表面钙调蛋白（CRT）转导的，CRT是一种已知的先天免疫受体，先前与免疫调节、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是一种有效的调节性T细胞（Treg）抑制剂和促血管生成、产生IL-17的T细胞（Th17）增强剂。在内皮细胞（ECs）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，在RA患者的滑膜中发现了瓜氨酸化的CRT，瓜氨酸化的CRT对SE的亲和力明显高于未修饰的蛋白，并且转导了更强的信号。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。本研究的主要目的是表征SE在血管生成中的作用，血管生成是包括RA在内的几种自身免疫性疾病的关键发病机制。具体而言，我们建议：1。利用小鼠耐受性和胶原诱导关节炎（CIA）模型表征se介导的Th17极化的功能效应；2. 测定SE-CRT对实验性小鼠血管生成和CIA模型EC活化的影响；3. 确定CRT瓜氨酸化在小鼠ECs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个新的范式，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. PUBLIC HEALTH RELEVANCE: This project will investigate a novel hypothesis regarding the mechanism of rheumatoid arthritis (RA). At the center on this project is a process called "angiogenesis" (new blood vessel formation). It has been previously noted that angiogenesis plays a central role in RA. The project proposed here will examine the hypothesis that certain gene products that are known to characterize RA, but their mechanism of action is unknown, are directly involved in promoting angiogenesis. If confirmed, the studies proposed here could improved understanding of RA and other autoimmune conditions, and may open the door to the design of new anti- angiogenesis treatment strategies.