Innate and Adaptive Immune Mechanisms in Arthritis

摘要 类风湿性关节炎是由于宿主免疫失调所致。自从我们最初克隆了 小鼠巨噬细胞移动抑制因子(MIF)，我们重点研究了该介体在MIF中的作用。 类风湿性关节炎的发病机制。我们证明了抗MIF在实验性关节炎中具有保护作用 我们报道了MIF能够推翻糖皮质激素免疫抑制，诱导持续激活 ERK1/2信号转导通路，通过抑制活化诱导的细胞凋亡促进炎症反应。这个 我们发现了高表达的MIF等位基因，证实了MIF在人类疾病中的重要性 它们与类风湿性关节炎的严重程度有关；这些数据最近在一项更大的多项研究中得到证实。 中心研究并扩展到幼年特发性关节炎。在目前的资金支持期间，我们阐明了MIF 通过为MIF(MIF-KO，MIF)的完全和细胞谱系特异性缺失创建遗传模型来发挥作用 FLOX)，我们开发了一种编码突变MIF的“敲入”小鼠，它解决了关于 蛋白质神秘的互变构酶活性。我们还证实，MIF信号转导需要一个 两种蛋白质的复合体：CD74与MIF结合，CD44通过激活Src启动信号传递 家族酪氨酸激酶。 在这一竞争性更新中，我们将重点关注最近阐明的MIF受体的功能。 我们的具体目标是：1.确定MIF受体复合体(CD74/CD44)在血管内皮细胞生长中的作用 适应性免疫反应。我们的工作假设是通过MIF受体的信号维持 活化的T淋巴细胞存活并调节适应性免疫反应。2.定义 MIF信号受体CD44和CD44异构体在血管内皮细胞损伤中的作用 类风湿性关节炎的免疫病理学。CD44剪接变异体在T细胞中的表达 与增强的运输反应有关；以及在基质细胞中，侵袭性增加 表型。我们的工作假设是MIF诱导CD44的选择性剪接，CD44调节 MIF依赖的反应，并在类风湿关节炎的免疫发病机制中起作用。3.识别 MIF结合受体(CD74)的高效小分子拮抗剂。结构-功能 研究表明，MIF的N-末端区域与MIF受体的CD74组分结合。我们会 评估被合理设计为与MIF N-末端区域结合的小分子的能力 抑制MIF与CD74的相互作用，改善实验性关节炎。 将获得的信息将有广泛的应用，因为它将提供机械性的洞察 MIF受体复合体(CD74/CD44)在类风湿免疫病理中的作用 关节炎。这些研究的翻译影响是，对MIF受体作用的更准确定义 将加速小分子MIF抑制剂的开发。这样的抑制剂可能会显示出最大的 具有高表达MIF等位基因并表现为MIF依赖形式的MIF患者的疗效 炎症性疾病。

ABSTRACT Rheumatoid arthritis results from a dysregulation in host immunity. Since our initial cloning of murine macrophage migration inhibitory factor (MIF), we have focused on the role of this mediator in the pathogenesis of rheumatoid arthritis. We showed that anti-MIF is protective in experimental arthritis and we reported on MIF's ability to override glucocorticoid immunosuppression, induce sustained activation of ERK1/2 MAP kinases, and promote inflammation by inhibiting activation-induced apoptosis. The importance of MIF in human disease was validated by our discovery of high-expression MIF alleles and their association with rheumatoid arthritis severity; these data were confirmed recently in a larger multi- center study and extended to juvenile idiopathic arthritis. In the currently funded period, we elucidated MIF function by creating genetic models for the complete and cell-lineage specific deletion of MIF (MIF-KO, mif flox), and we developed a "knock-in" mouse encoding a mutant MIF that resolved questions about the protein's enigmatic tautomerase activity. We also established that MIF signal transduction requires a complex of two proteins: CD74, which binds MIF, and CD44, which initiates signaling by activating Src family tyrosine kinases. In this competitive renewal, we will focus on the function of the recently elucidated MIF receptor. Our Specific Aims are: 1. Define the Role of the MIF Receptor Complex (CD74/CD44) in the Adaptive Immune Response. Our working hypothesis is that signaling through the MIF receptor sustains the survival of activated T lymphocytes and regulates the adaptive immune response. 2. Define the Functional Importance of the MIF Signaling Receptor, CD44, and of CD44 Variant Isoforms in the Immunopathology of Rheumatoid Arthritis. The expression of CD44 splice variants in T cells is associated with an enhanced trafficking response; and in stromal cells, with an increase in invasive phenotype. Our working hypothesis is that MIF induces the alternative splicing of CD44, which regulates MIF-dependent responses and contributes to the immunopathogenesis of rheumatoid arthritis. 3. Identify High-potency, Small Molecule Antagonists of the MIF Binding Receptor (CD74). Structure-function studies indicate that MIF's N-terminal region binds to the CD74 component of the MIF receptor. We will evaluate small molecules that were rationally designed to bind to the MIF N-terminal region for their ability to inhibit MIF interaction with CD74 and ameliorate experimentally-induced arthritis. The information to be gained will have broad application because it will provide mechanistic insight into how the MIF receptor complex (CD74/CD44) contributes to the immunopathology of rheumatoid arthritis. The translational impact of these studies is that a more precise definition of MIF-receptor action will accelerate the development of small molecule MIF inhibitors. Such inhibitors may show greatest efficacy in those patients with high-expression MIF alleles and who manifest an MIF-dependent form of inflammatory disease.