The treatment of uveitic cystoid macular edema with topical Interferon gamma

我们推测，适当的视网膜水合作用是由干扰素γ对视网膜色素上皮细胞的双峰功能平衡维持的。越来越多的证据有力地表明，免疫系统在血管生成中起着重要作用。促炎细胞因子如IFNg、IL-6、TNF α和IL-1b是眼部炎性疾病发病机制中的主要细胞因子，并且已被证明在RPE上具有受体。TNF α、IL-6和IL-1b被认为是促血管生成因子。然而，IFNg由于其对其他器官系统中的内皮细胞生长和毛细血管形成的抑制作用而被广泛接受为抗血管生成细胞因子。我们已经评估了干扰素γ对JAK/STAT途径的影响，JAK/STAT途径是一种也存在于人RPE细胞中的信号转导途径。进行流体转运测定以检查IFN是否诱导跨hfRPE单层的流体转运的变化。 将IFNg（10 ng/ml）添加到基础浴中使JV增加8.6 ulcm-2 hr-1，反映了从组织的视网膜侧到脉络膜侧的流体吸收的增加。通过跨上皮电位（TEP）和总组织电阻（RT）测量，细胞活力无明显变化。在10个实验中，平均JV从12.9 +/- 1.6增加到20.5 +/- 3.1 uL*cm-2*hr-1（平均值+/- s.e.m.，P< 0.01）。 使用先前测试的视网膜脱离的体内啮齿动物模型来测量INFg对视网膜脱离后再吸收的影响。通过将大约1 ul渗透平衡的改良磷酸盐缓冲盐水（MPBS）溶液注射到视网膜下间隙（SRS）中来产生初始脱离。使用在前30分钟内体积变化不超过10%的脱附物来测试INFg效应。 在通过OCT成像测量脱离稳定体积后，通过滴眼剂（Celluvisc）将INFg（40 μ l，100 ng/ml）添加到眼睛的前表面。在不同时间点记录一系列3D OCT图像。在观察的第一个小时内，将INFg添加到前眼表面引起视网膜脱离体积显著快速减少50%。该结果与体外观察到的RPE细胞中的液体转运增加一致。 我们假设在正常的RPE细胞中，两种途径同时起作用以维持正常的视网膜水合作用。如果从基底侧刺激Jak/Stat通路，将诱导液体吸收以解决水肿的异常积聚。Jak/Stat途径的其他调节靶点包括微小RNA 155（miR-155）、炎性小体和IL-18分泌。我们还假设RPE中稳态miR-155水平的单调升高随着年龄的增长而发生，有助于组成性炎性小体激活。IL-18和IFNg水平的调节可能导致逆转与葡萄膜炎相关的病理变化的治疗效果。

We hypothesize that proper retinal hydration is maintained by a balance of the bimodal functions of interferon gamma on the retinal pigment epithelium. Mounting evidence strongly suggests that the immune system plays an important role in angiogenesis. Pro-inflammatory cytokines, such as IFNg, IL-6, TNFa and IL-1b are the major cytokines in the pathogenesis of ocular inflammatory diseases and been shown to have receptors on RPE. TNFa, IL-6 and IL-1b are regarded as pro-angiogenic factors. However, IFNg is widely accepted as an anti-angiogenic cytokine due to its inhibitory effect on endothelial cell growth and capillary formation in other organ systems. We have evaluated the effect of interferon gamma on the JAK/STAT pathway, a signal transduction pathway also present in Human RPE cells. Fluid transport assays were performed to examine whether IFN induced changes in fluid transport across hfRPE monolayers. IFNg (10 ng/ml) addition to the basal bath increased JV by 8.6 ulcm-2hr-1, reflecting an increase in fluid absorption from the retinal to the choroidal side of the tissue. There were no apparent changes in cell viability as measured by transepithelial potential (TEP) and total tissue resistance (RT). In 10 experiments, the mean JV increased from 12.9 +/- 1.6 to 20.5 +/- 3.1 uL*cm-2*hr-1 (mean +/- s.e.m., P< 0.01). A previously tested in vivo rodent model of retinal detachment was used to measure the effect of INFg on re-absorption following retinal detachment. Initial detachment was created by injecting approximately 1ul of osmotically-balanced, modified phosphate-buffered saline (MPBS) solution into the sub-retinal space (SRS). Detachments that did not change in volume more than 10% in the first 30 minutes were used to test INFg effects. After detachment stabilization volume was measured by OCT imaging, INFg (40ul of 100ng/ml) was added to the anterior surface of the eye via eye drops (Celluvisc). A series of 3D OCT images were recorded at different time point. Addition of INFg to the anterior eye surface caused a significant, rapid 50% decrease in retinal detachment volume in the first hour of observation. This result is consistent with the observed fluid transport increase in RPE cells in vitro. We hypothesize that in the normal RPE cell, both pathways are functioning simultaneously to maintain the normal retinal hydration. The Jak/Stat pathway, if stimulated from basal side, will induce fluid absorption to resolve the abnormal accumulation of edema. Other regulatory targets of Jak/Stat pathway include micro RNA 155(miR-155), inflammasome, and IL-18 secretion. We also hypothesize that monotonic elevation of steady-state miR-155 levels in RPE occur with age, contributing to constitutive inflammasome activation. Modulation of IL-18 and IFNg levels may lead to therapeutic effect to reverse pathological changes associated with uveitis.