Citrullinated Antigens Bridge Innate and Adaptive Immunity in RA

瓜氨酸抗原桥接 RA 中的先天免疫和适应性免疫

• 批准号: 8243081
• 负责人: Jeremy B Sokolove
• 金额: --
• 依托单位: VETERANS ADMIN PALO ALTO HEALTH CARE SYS
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8243081
• 关键词: Adjuvant; Affect; Antibodies; Antibody Formation; Antibody-Producing Cells; Antigen-Antibody Complex; Antigen-Presenting Cells; Antigens; Arterial Fatty Streak; Arthritis; Autoantibodies; Autoantigens; Autoimmune Process; Autoimmunity; Automobile Driving; B Cell Proliferation; B-Cell Activation; B-Lymphocytes; Biological Markers; Blood; CD80 gene; Cardiovascular system; Cell Culture Techniques; Cell physiology; Chromatin; Chronic; Clinical; Clonal Expansion; Complement Factor B; Development; Disease; Etiology; Fc Receptor; Fibrinogen; Health Expenditures; Human; Immune response; Immune system; Immunization; Immunoglobulin Class Switching; Immunoglobulin G; Immunologic Receptors; In Vitro; Inflammation; Inflammation Mediators; Inflammatory; Joints; Lead; Legal patent; Life; Ligation; Lupus; MS4A1 gene; Mediating; Modeling; Modification; Morbidity - disease rate; Mus; Natural Immunity; Pathogenesis; Pathway interactions; Patients; Peripheral; Plasma Cells; Plasmablast; Play; Population; Production; Proliferating; Proteins; Receptors, Antigen, B-Cell; Refractory; Rheumatoid Arthritis; Rheumatoid Factor; Role; Serum; Signal Transduction; Site; Source; Synovial Fluid; Systemic Lupus Erythematosus; T-Cell Activation; TNF gene; TNFRSF5 gene; Therapeutic Intervention; Tissues; Toll-like receptors; Transgenic Organisms; United States; Veterans; adaptive immunity; arthritis therapy; arthropathies; autoimmune arthritis; autoreactive B cell; base; bone; cyclic citrullinated peptide; cytokine; disability; improved; insight; macrophage; mortality; novel; novel therapeutic intervention; precursor cell; receptor; research study; response; rituximab; success; toll-like receptor 4; tositumomab

DESCRIPTION (provided by applicant): Rheumatoid arthritis (RA), the most common inflammatory joint disease of autoimmune etiology, affects nearly 1% of the population. It is clear that the adaptive and innate immune systems are important in the pathogenesis of RA. Autoantibodies that target citrullinated proteins are specific to RA, and innate immune receptors such as Toll-like receptors (TLRs) play important roles in the induction of both inflammation and adaptive immunity (e.g. B- and T-cell activation). A recently identified target of the anti-citrullinated protein antibody (ACPA) response in RA is citrullinated fibrinogen (cFb). We demonstrated that immune complexes (ICs) containing cFb (cFb-IC) are present in the blood and synovial tissue of patients with RA, and that immunization of mice with cFb induces inflammatory arthritis. Why cFb-specific autoimmunity should mediate inflammatory arthritis remains unclear. Investigating the mechanisms by which immunization with cFb evokes inflammatory arthritis, we observed that cFb itself is a powerful innate adjuvant that signals through TLR4, and that cFb-IC can synergize to augment macrophage TNF production by co-ligating TLR4 and the Fc3 receptor (Fc3R). Our preliminary studies also indicate that cFb can stimulate proliferation of B cells in a TLR4- dependent manner. In addition, we identified significantly elevated levels of plasmablasts-the early, activated B cells-in the blood of ACPA-positive RA patients. These circulating plasmablasts produce large amounts of ACPA, including anti-cFb antibodies, suggesting that ACPA-positive RA is associated with ongoing, antigen- driven activation of peripheral B cells. Finally, we detected the presence of citrullinated proteins, including citrullinated fibrinogen, not only in the inflamed joint, but also within the atherosclerotic plaque of RA and non- RA subjects. Our overriding hypothesis is that inflammation in RA is mediated by cFb-IC, which drive proinflammatory responses by augmenting macrophage TNF production, and adaptive immune responses by activating B cells specific for cFb; and that the innate and adaptive immune response induced by cFb-IC together propagate the synovial and extra-articular manifestations of RA. We aim to demonstrate 1) that antigen-driven B-cell activation results in plasmablast formation, and that these plasmablasts are a major source of ACPA and 2) that TLR4 is upregulated on B cells at sites of chronic inflammation and that cFb-IC can co-stimulate these B cells via co-ligation of TLR4 and the B-cell receptor. To achieve these aims we will use novel and established models of immune complex arthritis, in vitro cell culture and flow-cytometric analysis,and a novel bead-based antigen microarrayfor profiling of RA patients' autoantibodies as well as antibodies produced by cultured plasmablast. Success of these studies will provide insight into the pathways mediating inflammation in RA, as well as further evidence of autoantigen-driven clonal expansion of self- reactive B cells. Proinflammatory cytokines and B cells are both targeted by current RA therapies, and an improved understanding of the mechanisms of innate and adaptive immune responses in RA could yield new and potentially better targets for disease prognostication as well as therapeutic intervention. PUBLIC HEALTH RELEVANCE: Rheumatoid arthritis (RA) is a chronic autoimmune arthritis that affects nearly 1% of the United States population and is a leading cause of disability and health-care expenditures among veterans. Success of the proposed experiments would demonstrate that citrullination-a specific modification of the body's proteins- and the development of autoantibodies that target citrullinated proteins are crucial not only to morbidity caused by inflammation of the joints, but potentially also to the increased cardiovascular mortality associated with RA. The proposed experiments will provide insights into diseaes pathogenesis that could lead to development of new therapeutic approaches for RA and its associated disability.

描述（由申请人提供）： 类风湿性关节炎 (RA) 是最常见的自身免疫性炎症性关节疾病，影响着近 1% 的人口。很明显，适应性和先天免疫系统在 RA 的发病机制中很重要。靶向瓜氨酸蛋白的自身抗体对 RA 具有特异性，而 Toll 样受体 (TLR) 等先天免疫受体在炎症和适应性免疫（例如 B 细胞和 T 细胞激活）的诱导中发挥着重要作用。最近确定的 RA 中抗瓜氨酸蛋白抗体 (ACPA) 反应的靶标是瓜氨酸纤维蛋白原 (cFb)。我们证明，RA 患者的血液和滑膜组织中存在含有 cFb (cFb-IC) 的免疫复合物 (IC)，并且用 cFb 免疫小鼠会诱导炎症性关节炎。为什么 cFb 特异性自身免疫会介导炎症性关节炎仍不清楚。在研究 cFb 免疫诱发炎症性关节炎的机制时，我们观察到 cFb 本身是一种强大的先天佐剂，通过 TLR4 发出信号，并且 cFb-IC 可以通过共连接​​ TLR4 和 Fc3 受体 (Fc3R) 协同增强巨噬细胞 TNF 的产生。我们的初步研究还表明，cFb 可以以 TLR4 依赖性方式刺激 B 细胞增殖。此外，我们还发现 ACPA 阳性 RA 患者血液中浆母细胞（早期活化的 B 细胞）水平显着升高。这些循环浆母细胞产生大量 ACPA，包括抗 cFb 抗体，表明 ACPA 阳性 RA 与抗原驱动的外周 B 细胞持续激活有关。最后，我们检测到瓜氨酸蛋白（包括瓜氨酸纤维蛋白原）的存在，不仅存在于发炎关节中，而且存在于 RA 和非 RA 受试者的动脉粥样硬化斑块中。我们最重要的假设是，RA 炎症是由 cFb-IC 介导的，cFb-IC 通过增加巨噬细胞 TNF 的产生来驱动促炎反应，并通过激活 cFb 特异性的 B 细胞来驱动适应性免疫反应； cFb-IC 诱导的先天性和适应性免疫反应共同传播 RA 的滑膜和关节外表现。我们的目标是证明 1) 抗原驱动的 B 细胞激活导致浆母细胞形成，并且这些浆母细胞是 ACPA 的主要来源；2) TLR4 在慢性炎症部位的 B 细胞上表达上调，并且 cFb-IC 可以通过 TLR4 和 B 细胞受体的共连接来共同刺激这些 B 细胞。为了实现这些目标，我们将使用新型和已建立的免疫复合物关节炎模型、体外细胞培养和流式细胞术分析，以及新型基于珠子的抗原微阵列来分析 RA 患者的自身抗体以及培养的浆母细胞产生的抗体。这些研究的成功将提供对 RA 炎症介导途径的深入了解，以及自身抗原驱动的自身反应性 B 细胞克隆扩张的进一步证据。促炎细胞因子和 B 细胞都是当前 RA 治疗的目标，更好地了解 RA 中先天性和适应性免疫反应的机制可能会为疾病预测和治疗干预产生新的、可能更好的目标。 公共卫生相关性： 类风湿性关节炎 (RA) 是一种慢性自身免疫性关节炎，影响着近 1% 的美国人口，是退伍军人残疾和医疗保健支出的主要原因。拟议实验的成功将证明瓜氨酸化（人体蛋白质的一种特定修饰）和针对瓜氨酸化蛋白质的自身抗体的开发不仅对于关节炎症引起的发病至关重要，而且还可能对于与 RA 相关的心血管死亡率增加至关重要。拟议的实验将提供对疾病发病机制的深入了解，从而可能导致开发治疗 RA 及其相关残疾的新治疗方法。