COSTIMULATORY REGULATION OF TH1/TH2 CYTOKINES IN EAE

实验性自身免疫性脑脊髓炎（EAE）是一种炎症性疾病， 由髓鞘抗原引起的中枢神经系统疾病， 特异性致脑炎性CD 4 + Th 1细胞。 有人建议 疾病的恢复或保护由Th 2细胞介导。 然而，在这方面， 负责启动和维持的关键细胞因子 以及那些介导恢复和复发的疾病仍然存在 不确定在免疫反应期间，T细胞需要2个信号， 全面激活。 第一信号由TCR的接合提供 用抗原肽加上抗原呈递细胞上的MHC分子 第二种“共刺激”信号通过与ACP的结合提供，第二种“共刺激”信号通过与ACP的结合提供。 T细胞上的特异性受体及其APC上的配体。 最好的 特征性共刺激途径是由T细胞上的CD 28提供的 结合至专业APC上的B7-1和B7-2。 另一种共刺激 信号通过APC表面上的CD 40与 T细胞表面的CD 40 L。 特异性共刺激分子的作用 Th 1与Th 2细胞分化的分子仍不清楚。 STAT4 敲除小鼠不能响应IL-12信号传导， 无法建立Th 1应答。 STAT 6基因敲除小鼠不能 对IL-4产生应答，因此不能产生Th 2应答。我们有 使用STAT 4和STAT 6敲除小鼠的初步数据表明， Th 1和Th 2细胞受共刺激因子的不同调节 在抗原引发期间激活。 本提案的目的是剖析以下因素之间的相互作用 特异性T细胞共刺激活化途径（CD 28/CTLA 4-B7和 CD 40 L-CD 40）和Th 1和Th 2细胞因子在调节免疫应答中的作用 在临床相关的自身免疫性疾病模型中体内，其特征在于 缓解和复发。 首先，我们将研究Th 1和Th 2的作用 启动疾病、影响恢复或导致复发的细胞因子 使用STAT 4和STAT 6基因敲除小鼠， 与EAE易感菌株回交。 我们还将使用MBP TCR 转基因小鼠与STAT KO小鼠杂交以解决机制。 其次，我们将研究共刺激信号（CD 28，CD 40 L， 和CTLA 4）阻断。 我们还将 确定阻断CD 28-B7或CD 40 L-CD 40在 体内Th 1或Th 2应答的产生。这些研究应 对自身免疫性疾病具有相关的临床意义， 多发性硬化症，并可能提供发展的基本原理， 靶向阻断T细胞共刺激的新疗法 免疫介导的疾病。

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the central nervous system initiated by myelin antigen- specific encephalitogenic CD4+ Th1 cells. It has been suggested that recovery or protection from disease is mediated by Th2 cells. However, the critical cytokines responsible for the initiation and maintenance of disease, as well as those mediating recovery and relapse remain uncertain. During an immune response, the T cell requires 2 signals for full activation. The first signal is provided by engagement of the TCR with the antigenic peptide plus MHC molecule on antigen-presenting cells (ACPs), and the second "costimulatory" signal is provided by binding of specific receptors on T cells with their ligand/s on APCs. The best characterized costimulatory pathway is that provided by CD28 on T cells binding to B7-1 and B7-2 on professional APCs. Another costimulatory signal is provided by interaction of CD40 on the surface of APCs with CD40L on the surface of T cells. The role of specific costimulatory molecules in Th1 versus Th2 cell differentiation remains unclear. STAT4 knockout mice are unable to respond to IL-12 signaling and are thus unable to mount a Th1 response. STAT6 knockout mice are unable to respond to IL-4 and thus cannot mount a Th2 response. We have preliminary data using STAT 4 and STAT 6 knockout mice that suggest that Th1 and Th2 cells are differentially regulated by costimulatory activation during antigen priming. The purpose of this proposal is to dissect the interplay between specific T cell costimulatory activation pathways (CD28/CTLA4-B7 and CD40L-CD40) and Th1 and Th2 cytokines in regulating immune responses in vivo in a clinically relevant autoimmune disease model characterized by remissions and relapses. First, we will study the role of Th1 and Th2 cytokines in initiating disease, effecting recovery, or causing relapses using STAT 4 and STAT 6 knockout mice which have been extensively backcrossed unto EAE susceptible strains. We will also use MBP TCR transgenic mice intercrossed with STAT KO mice to address mechanisms. Second, we will study mechanisms of costimulatory signal (CD28, CD40L, and CTLA4) blockade in STAT 4 and STAT 6 knockout mice. We will also determine the differential effects of blocking CD28-B7 or CD40L-CD40 in the generation of a Th1 or Th2 response in vivo. These studies should have relevant clinical implications for autoimmune diseases such as multiple sclerosis, and may provide the rationale for development of novel therapies targeted at blocking T cell costimulation in immunologically mediated diseases.