INNATE AND ADAPTIVE MECHANISMS IN ARTHRITIS

描述（由申请人提供）：类风湿关节炎会导致严重的残疾和死亡率增加。目前对其发病机制的研究主要集中在宿主免疫失调产生病理改变的机制上。巨噬细胞迁移抑制因子（MIF）是先天（单核细胞/巨噬细胞）和适应性（T细胞）免疫细胞产生的免疫反应的上游调节剂。我们已经发现人类MIF基因（MIF）是由功能不同的等位基因编码的，并且高表达的MIF等位基因在类风湿关节炎患者中被过度代表。我们还发现细胞表面蛋白CD74是MIF的细胞受体。我们认为，先天或适应性免疫反应产生的MIF过量及其与CD74的结合在类风湿关节炎的发病机制中发挥了内在作用。本应用程序的目的是确定炎症性关节炎中MIF产生和作用的细胞基础。核心假设是炎症性关节炎是由单核细胞/巨噬细胞或T细胞过量产生MIF引起的，同时MIF通过与CD74结合激活靶细胞。这项研究的基本原理是，一旦知道炎症性关节炎中MIF产生和作用的分子基础，那么就可以更精确地了解这种疾病的免疫失调。我们将通过以下三个具体目标来验证我们的假设并实现这一应用的目标：1)通过研究单核细胞特异性和T细胞特异性MIF敲除小鼠来确定MIF在炎性关节炎中的作用。我们将在单核细胞来源的MIF或T细胞来源的MIF基因缺陷的MIF -floxed小鼠中检查关节炎的发展。2)在体内建立MIF/CD74相互作用的病理作用。我们将通过给予具有实验性关节炎的野生型小鼠中和性抗CD74单抗或可溶性CD74蛋白（sCD74）来确定MIF/CD74相互作用的病理重要性。3)确定高表达与低表达的Mif等位基因在Mif产生、细胞激活和人类单核细胞和T细胞下游细胞因子表达中的作用我们将从类风湿关节炎患者身上获得单核细胞和T细胞，分析Mif基因型，研究Mif的产生、细胞活化和下游细胞因子的表达。这些结果将具有重要意义，因为它们将提供对MIF在连接先天免疫和适应性免疫的途径中的作用的更精确的理解，并使其变得失调以产生炎症性关节炎。此外，它们将根据Mif等位基因为识别严重类风湿关节炎高风险人群提供科学依据，从而采取措施更好地治疗他们的糜烂性疾病。

DESCRIPTION (provided by applicant): Rheumatoid arthritis causes significant disability and increased mortality. Research into its pathogenesis currently focuses on the mechanisms by which host immunity becomes dysregulated to produce pathologic changes. Macrophage migration inhibitory factor (MIF) is an upstream regulator of the immune response that is produced both by innate (monocyte/macrophage) and adaptive (T cell) immune cells. We have discovered that the human MIF gene (Mif) is encoded by functionally distinct alleles, and that high-expression Mif alleles are over-represented in patients with rheumatoid arthritis. We also have identified the cell surface protein, CD74, to be a cellular receptor for MIF. We suggest that MIF overproduction by the innate or the adaptive immune response and its binding to CD74 play an intrinsic role in the pathogenesis of rheumatoid arthritis. The objective of this application is to define the cellular basis of MIF production and action in inflammatory arthritis. The central hypothesis is that inflammatory arthritis results from an overproduction of MIF by monocytes/macrophages or by T cells, coupled with MIF activation of target cells by binding to CD74. The rationale for this proposed research is that once the molecular basis for MIF production and action in inflammatory arthritis is known, then a more precise understanding of immune dysregulation in this disease will have been achieved. We will test our hypothesis and accomplish the objective of this application by pursuing three specific aims: 1) Define MIF's Role in Inflammatory Arthritis by Studying Monocyte-specific and T cell-specific Mif-Knockout Mice. We will examine arthritis development in Mif-floxed mice made genetically-deficient either for monocyte-derived MIF, or for T cell-derived MIF. 2) Establish the Pathologic Role of the MIF/CD74 Interaction In Vivo. We will establish the pathologic importance of the MIF/CD74 interaction by administering a neutralizing anti- CD74 mAb, or a soluble CD74 protein (sCD74), to wild-type mice with experimental arthritis. 3) Define the Role of High- versus Low-expression Mif alleles in MIF Production, Cellular Activation, and Downstream Cytokine Expression by Human Monocytes and T Cells. We will obtain monocytes and T cells from patients with rheumatoid arthritis, analyze the Mif genotype, and study MIF production, cellular activation, and downstream cytokine expression. These results will be significant because they will provide a more precise understanding of MIF's role in the pathways that link innate and adaptive immunity, and which become dysregulated to produce inflammatory arthritis. Moreover, they will provide a scientific rationale for identifying individuals who may be a high risk for severe rheumatoid arthritis - based on their Mif alleles, so that steps can be taken to better treat their erosive disease.