Regulation of JAK/STAT pathways in the eye

炎性细胞因子IL-23诱导原始T细胞产生由产生IL-17的T辅助细胞（Th17）主导的免疫应答，所述T辅助细胞与包括葡萄膜炎和巩膜炎的几种人类炎性疾病的病因学有关。IL-23通过激活STAT3途径介导其生物活性。最近的报道还表明，STAT3是幼稚T细胞向Th17发育途径定向所必需的，表明STAT3途径参与CNS炎性疾病。最近在实验性自身免疫性葡萄膜视网膜炎（EAU）中确立了Th17在葡萄膜炎病因学中的作用，EAU是一种T细胞介导的眼内炎性疾病，其与人类葡萄膜炎具有基本的免疫病理学特征。在CD4 + T细胞中靶向缺失STAT3的小鼠不会发展EAU或实验性自身免疫性脑炎或EAE（多发性硬化症的小鼠模型），因为它们不能产生致病性Th17细胞。STAT3也是2 - 4整合素活化和T细胞运输到CNS所必需的：炎性STAT3缺陷型T细胞不会进入眼睛或大脑。αβ因此，STAT3是一个有吸引力的治疗靶点，可用于抑制葡萄膜炎。这项研究的重点是STAT3通路的治疗靶向。已经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蛋白靶向STAT3通路。SOCS3是STAT3通路的有效内源性细胞内抑制剂。我们已经产生了与Karposi FGF4蛋白的信号肽的疏水性12个AA序列融合的重组SOCS3蛋白。这种重组SOCS3蛋白可以穿透细胞膜，我们已经用它来抑制巨噬细胞和T细胞中IL-6诱导的STAT3活化。我们还使用这种蛋白质来抑制体外极化Th17细胞的扩增，我们的下一步是优化它用于EAU的动物研究。(ii)由小化学分子组成的STAT3抑制剂（NCE）最近由Orchid Research Labs Limited，Chennai，India开发。NCE是STAT3的选择性抑制剂，在肿瘤学的临床前模型中有效。通过NEI和Orchid Research Labs之间的MTA协议，我们获得了这种化合物，并评估了其对葡萄膜炎的疗效。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.