Pathogenic Role of Malondialdehyde-Acetaldehyde Adducts in Rheumatoid Arthritis

据估计，风湿病学家诊断的风湿性关节炎（RA）见于高达2%的 使用者保健此外，与女性RA相比，男性RA（主要VA人口统计学） 导致更高的发病率、更高频率的关节外表现和更差的疾病相关性 成果。随着老龄化和主要是男性退伍军人人口，预计 RA将在未来几年在VA急剧增长。鉴于RA与以下疾病的相关性，这是高度相关的; 退伍军人的死亡风险大大增加，除了与工作有关的残疾率高， 仅在美国，社会成本就接近400亿美元。在过去的几年里， 我们对RA发病机制的认识有了新的进展。抗瓜氨酸蛋白抗体（ACPA）具有高度特异性 最近的研究表明，ACPA是致病性的，血清阳性预示着不良的 预后包括更快速的关节破坏。然而，瓜氨酸化蛋白/ 肽在共刺激分子的背景下被识别、加工和呈现仍然不是 很好理解。研究表明，一种独特的蛋白质翻译后修饰， 发生在氧化应激下的丙二醛（MDA）和乙醛（AA），称为MAA，向上- 调节MHC II类，增加共刺激分子，产生细胞毒性和促炎性 在没有外源性佐剂的情况下的反应。这是我们小组第一次证明MAA修饰了 在RA患者的滑膜组织中检测到蛋白质并与瓜氨酸化抗原共定位。此外，本发明还 抗MAA抗体同种型与患者中ACPA浓度独立相关（p < 0.0001） 建立的RA。因此，我们的总体假设是，这两个翻译后 修饰（MAA修饰和瓜氨酸）协同作用，导致耐受性丧失， RA的抗瓜氨酸自身免疫反应特征。为了研究这一假设， 目的1将评价对瓜氨酸和/或瓜氨酸盐的适应性免疫应答（自身抗体和T细胞应答）。 MAA修饰的蛋白质。我们预期，与仅瓜氨酸化或仅MAA的抗原相比， 在免疫后的小鼠中和RA中， 患者先前的数据已经证明，SR介导MAA修饰的蛋白质的生物学效应 Aim 2旨在鉴定介导APC和其他细胞作用的特异性SR， 瓜氨酸化和/或MAA修饰的蛋白。在子目标1中，研究将利用中国的 卵巢（CHO）细胞系，已经在我们的实验室，并已转染 各种SR中的每一个。初始实验的结果将为后续结合研究的设计提供信息 使用人APC（同时表达多种SR）和滑膜组织特有的细胞类型。使用 单独或组合的可用SR抑制剂将有助于确定在每个细胞上发现哪些受体 类型.在子目标2中，将重点关注生物学效应（纤维化、炎症、钙内流、PAD MAA修饰的和/或瓜氨酸化的蛋白质与不同细胞的结合 类型因此，该提议的创新方面是其关注于融合两种天然存在的生物活性物质。 事件（瓜氨酸和氧化应激）共同启动高度特异性的自身免疫反应， 促进RA的发生和发展。

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.