Regulation of JAK/STAT pathways in the eye

炎性细胞因子IL-23诱导NAVE T细胞启动以IL-17产生的T辅助细胞(Th17)为主的免疫反应，Th17与多种人类炎症性疾病的病因有关，包括葡萄膜炎和巩膜炎。IL-23通过激活STAT3通路介导其生物学活性。最近的报道也表明，STAT3是幼稚T细胞向Th17发育途径承诺所必需的，提示STAT3途径参与了中枢神经系统炎症性疾病。Th17在葡萄膜炎病因中的作用最近在实验性自身免疫性葡萄膜视网膜炎(EAU)中得到证实，EAU是一种T细胞介导的眼内炎症性疾病，具有与人类葡萄膜炎相同的基本免疫病理特征。靶向缺失CD4+T细胞中STAT3的小鼠不会发展为EAU或实验性自身免疫性脑炎或EAE(多发性硬化症小鼠模型)，因为它们无法产生致病的Th17细胞。STAT3也是整合素激活和T细胞转运到中枢神经系统所必需的：炎性STAT3缺陷的T细胞不会进入眼睛或大脑。因此，STAT3是一个有吸引力的治疗靶点，可用于抑制葡萄膜炎。本研究主要针对STAT3信号转导通路进行靶向治疗。我们使用了两种实验方法。(I)在第一组研究中，通过使用膜穿透SOCS3蛋白来靶向STAT3通路。SOCS3是STAT3途径的内源性细胞内抑制物。我们已经产生了一个重组的SOCS3蛋白，它与Karposi FGF4蛋白的信号肽的疏水12个氨基酸序列融合在一起。这种重组的SOCS3蛋白可以穿透细胞膜，我们已经用它来抑制IL-6诱导的巨噬细胞和T细胞中STAT3的激活。我们还使用这种蛋白来抑制体外极化的Th17细胞的扩张，我们的下一步是优化它，用于EAU的动物研究。(2)印度金奈的兰花研究实验室有限公司最近开发了一种由小化学分子组成的STAT3抑制剂(NCE)。NCE是STAT3的选择性抑制剂，在肿瘤学的临床前模型中一直有效。通过NEI和兰花研究实验室之间的MTA协议，我们获得了这种化合物，并评估了它对葡萄膜炎的疗效。我们在实验性自身免疫性葡萄膜炎模型中的研究表明，它可以抑制后葡萄膜炎的进展。我们还用其他STAT3抑制剂验证了这些结果。

The inflammatory cytokine, IL-23, induces nave T cells to mount immune responses dominated by IL-17 producing T-helper cells (Th17) that have been implicated in the etiology of several human inflammatory diseases, including uveitis and scleritis. IL-23 mediates its biological activities through activation of STAT3 pathways. Recent reports have also indicated that STAT3 is required for commitment of naive T cells towards the Th17 developmental pathway, suggesting involvement of STAT3 pathway in CNS inflammatory diseases. The role of Th17 in etiology of uveitis was recently established in experimental autoimmune uveoretinitis (EAU), a T cell-mediated intraocular inflammatory disease that shares essential immunopathologic features with human uveitis. Mice with targeted deletion of STAT3 in CD4+ T-cells do not develop EAU or experimental autoimmune encephalitis or EAE (mouse model of multiple sclerosis) because of their inability to generate pathogenic Th17 cells. STAT3 is also required for α2β4 integrin activation and T cell trafficking into CNS: inflammatory STAT3-deficient T cells do not enter the eye or brain. STAT3 is therefore an attractive therapeutic target that can be used to inhibit uveitis. This study focuses on therapeutic targeting of STAT3 pathways. Two experimental approaches have been used. (i) In the first set of studies, STAT3 pathways were targeted by using a membrane-penetrating SOCS3 proteins. SOCS3 is a potent endogenous intracellular inhibitor of STAT3 pathways. We have generated a recombinant SOCS3 protein that is fused to a hydrophobic 12 AA sequence of the signal peptide of the Karposi FGF4 protein. This recombinant SOCS3 protein can penetrate the cell membrane and we have used it to inhibit IL-6-induced STAT3 activation in macrophages and T cells. We have also used this protein to inhibit the expansion of polarized Th17 cells in vitro and our next step is to optimize it for use in animal studies of EAU. (ii) A STAT3 inhibitor (NCE) comprised of a small chemical molecule was recently developed by Orchid Research Labs Limited, Chennai, India. NCE is a selective inhibitor of STAT3 and has been effective in pre-clinical models of oncology. Through an MTA agreement between the NEI and Orchid Research Labs we obtained this compound and have evaluated its efficacy against uveitis. Our studies in the experimental autoimmune uveitis model reveal that it inhibits the progression of posterior uveitis. We have also validated these results with other STAT3 inhibitors.