COSTIMULATORY REGULATION OF TH1/TH2 CYTOKINES IN EAE

实验性自身免疫性脑脊髓炎是一种炎症性疾病 由髓鞘抗原引发的中枢神经系统疾病- 特异性脑源性CD4Th1细胞。有人建议， 疾病的恢复或保护是由Th2细胞介导的。然而， 负责启动和维持的关键细胞因子 疾病，以及那些调解康复和复发的人仍然存在 不确定。在免疫反应过程中，T细胞需要2个信号 完全激活。第一个信号通过TCR的接合来提供 抗原肽加MHC分子在抗原提呈细胞上的作用 (ACPs)，第二个“共刺激”信号通过结合 T细胞上的特异性受体及其配体/APC上的S。最好的 特征性的共刺激途径是CD28在T细胞上提供的途径 与专业APC上的B7-1和B7-2结合。另一种共刺激 信号是通过APC表面CD40与APC相互作用而提供的 T细胞表面CD40L。特异性共刺激分子的作用 Th1和Th2细胞分化中的分子尚不清楚。状态4 基因敲除的小鼠不能对IL-12信号产生反应，因此 无法装载Th1响应。STAT6基因敲除小鼠不能 对IL-4产生应答，因此不能产生Th2应答。我们有 使用STAT4和STAT6基因敲除小鼠的初步数据表明 共刺激分子对Th1和Th2细胞的差异性调节 在抗原启动过程中的激活。 这项建议的目的是剖析 特异性T细胞共刺激激活通路(CD28/CTLA4-B7和 CD40L-CD40)和Th1、Th2细胞因子在免疫调节中的作用 在临床上相关的自身免疫性疾病模型中的活体 缓解和复发。首先，我们将研究Th1和Th2的作用 细胞因子在引发疾病、影响康复或导致复发中的作用 使用STAT4和STAT6基因敲除小鼠，这些小鼠已经被广泛 回交到EAE敏感品系。我们还将使用MBP TCR 转基因小鼠与STAT KO小鼠杂交以研究机制。 第二，我们将研究共刺激信号(CD28，CD40L， 和CTLA4)阻断STAT4和STAT6基因敲除小鼠。我们还将 确定封闭CD28-B7或CD40L-CD40的不同效应 在体内产生Th1或Th2反应。这些研究应该 对自身免疫性疾病有相关的临床意义，如 多发性硬化症，并可能提供发展的理论基础 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.