Pathogenic Role of Malondialdehyde-Acetaldehyde Adducts in Rheumatoid Arthritis

据估计，风湿科医生诊断的类风湿性关节炎(RA)在多达2%的 退伍军人管理局医疗保健的用户。此外，与女性类风湿性关节炎相比，男性类风湿性关节炎(退伍军人管理局的主要人口统计) 导致更高的发病率，更高频率的关节外表现，以及更糟糕的疾病相关 结果。随着人口老龄化和以男性为主的退伍军人人口，预计 RA在未来几年将在退伍军人管理局戏剧性地增长。这是高度相关的，因为类风湿关节炎与； 退伍军人的死亡风险大大增加，此外还有与工作有关的高伤残率，以及每年 仅在美国，社会成本就接近400亿美元。在过去的几年里，有大量的 类风湿关节炎发病机制的研究进展。抗瓜氨酸蛋白抗体(ACPA)具有高度特异性 最近的研究表明，ACPA是致病的，血清阳性预示着一种较差的 预后包括更快的关节破坏。然而，瓜氨酸蛋白/的机制(S) 多肽是在协同刺激分子的背景下被识别和处理并呈现的，目前还不是 很好理解。研究表明，蛋白质的一种独特的翻译后修饰 在丙二醛(MDA)和乙醛(AA)的氧化应激下发生，称为MAA，UP- 调节MHC II类，增加共刺激分子，产生细胞毒性和促炎作用 在没有外源佐剂的情况下的反应。我们的小组第一次证明了MAA可以改变 在RA患者的滑膜组织中检测到蛋白质，并与瓜氨酸抗原共定位。另外， 抗MAA抗体亚型与患者的ACPA浓度(p&lt；0.0001)独立相关 与已建立的RA合作。因此，我们的首要假设是，这两个后翻译 修饰(MAA修饰和瓜氨酸化)协同作用，导致耐受性丧失 类风湿性关节炎特有的抗瓜氨酸自身免疫反应。为了研究这一假说，在 目标1将评估对瓜氨酸和/或 MAA修饰的蛋白质。我们预计，与仅含有瓜氨酸或MAA的抗原相比， 在免疫后的小鼠和RA中，对共修饰蛋白的修饰的免疫应答将更高 病人。先前的数据已经证明，SRS介导MAA修饰的蛋白质的生物学效应 在APC和其他细胞上，AIM 2旨在识别介导APC效应的特定SRs 类风湿关节炎中的瓜氨酸和/或MAA修饰蛋白。在次级目标#1中，研究将利用中国仓鼠 本实验室已有的卵巢(CHO)细胞系 各种SR中的每一个。初步实验的结果将为后续结合研究的设计提供信息 使用人类APC(同时表达多个SR)和滑膜组织特有的细胞类型。vbl.使用 可用的SR抑制剂单独或联合使用将有助于确定每个细胞上发现的受体 打字。在次级目标2中，将重点关注生物效应(纤维化、炎症、钙内流、PAD MAA修饰和/或瓜氨酸蛋白与不同细胞结合的表达和瓜氨酸化 类型。因此，这项提议的创新方面是它的重点是将两种自然发生的生物 共同启动高度特异的自身免疫反应的事件(瓜氨酸和氧化应激)， 促进类风湿关节炎的发展和进步。

It has been estimated that rheumatologist-diagnosed Rheumatoid arthritis (RA) is seen in up to 2% of the users of VA healthcare. Moreover, compared to RA in women, RA in men (the primary VA demographic) leads to greater morbidity, a higher frequency of extra-articular manifestations, and worse disease-related outcomes. With an aging and predominantly male veteran population, it is anticipated that the burden posed by RA will grow dramatically in the VA in coming years. This is highly relevant given the association of RA with; substantially higher mortality risk among veterans, in addition to high rates of work-related disability, and annual societal costs approaching $40 billion in the US alone. Over the past few years, there have been substantial advances in our understanding of RA pathogenesis. Anti-citrullinated protein antibody (ACPA) is highly specific to RA with recent studies suggesting that ACPA are pathogenic with seropositivity portending a poor prognosis including more rapid joint destruction. However, the mechanism(s) by which citrullinated proteins/ peptides are recognized and processed and presented in the context of co-stimulatory molecules is still not well understood. Studies have shown that a unique post-translational modification of proteins that occurs under oxidative stress by malondialdehyde (MDA) and acetaldehyde (AA), termed MAA, up- regulates MHC Class II, increases co-stimulatory molecules and generates cytotoxic and pro-inflammatory responses in the absence of exogenous adjuvant. For the first time, our group has shown that MAA modified proteins are detected in synovial tissues of RA patients and co-localize with citrullinated antigen. Additionally, anti-MAA antibody isotypes are independently associated with ACPA concentration (p < 0.0001) in patients with established RA. Therefore, our overarching hypothesis is that these two post-translational modifications (MAA modification and citrullination) act in concert to drive tolerance loss resulting in the anti-citrulline autoimmune responses characteristic of RA. To investigate this hypothesis, studies in Aim 1 will evaluate adaptive immune responses (autoantibody and T cell responses) to citrullinated and/or MAA-modified proteins. We anticipate that compared to antigens that are only citrullinated or only MAA modified, immune responses to co-modified proteins will be higher in mice following immunization and in RA patients. As prior data has demonstrated that SRs mediate the biological effects of MAA-modified proteins on APCs and other cells, Aim 2 is designed to identify the specific SRs that mediate the effects of citrullinated and/or MAA-modified proteins in RA. In Sub-Aim #1, studies will leverage Chinese Hamster Ovary (CHO) cell lines that are already available in our laboratory and that have been transfected with each of the various SRs. Results of initial experiments will inform the design of subsequent binding studies using human APCs (that simultaneously express multiple SRs) and cell types unique to synovial tissue. Using available SR inhibitors alone or in combination will aid in defining which receptors are found on each cell type. In Sub-Aim #2, will focus on the biological effects (fibrosis, inflammation, calcium influx, PAD expression and citrullination) of the binding of MAA modified and/or citrullinated proteins to the different cell types. Thus, the innovative aspect of this proposal is its focus on the melding of two naturally occurring biological events (citrullination and oxidative stress) that conspire to initiate highly specific autoimmune responses, promoting the development and progression of RA.