The treatment of uveitic cystoid macular edema with topical Interferon gamma

我们假设适当的视网膜水合作用是由干扰素γ在视网膜色素上皮上的双峰功能的平衡维持的。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、TNFa和IL-1b是眼部炎性疾病发病的主要细胞因子，并在RPE上有受体。tnf、IL-6和IL-1b被认为是促血管生成因子。然而，IFNg被广泛认为是一种抗血管生成的细胞因子，因为它对其他器官系统的内皮细胞生长和毛细血管形成有抑制作用。我们已经评估了干扰素γ对JAK/STAT通路的影响，这是一种同样存在于人RPE细胞中的信号转导通路。进行了流体输送试验，以检查IFN是否诱导了hfRPE单层间流体输送的变化。基础液中添加IFNg （10 ng/ml）可使JV增加8.6 ulcm-2hr-1，反映了从视网膜到组织脉络膜侧的液体吸收增加。经上皮电位（TEP）和总组织阻力（RT）测定细胞活力无明显变化。10个实验中，平均JV由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）。采用先前测试过的视网膜脱离啮齿动物体内模型来测量INFg对视网膜脱离后再吸收的影响。通过向视网膜下间隙（SRS）注射约1ul渗透压平衡的改性磷酸盐缓冲盐水（MPBS）溶液，形成初始脱离。在前30分钟内体积变化不超过10%的分离体被用来测试INFg效应。在OCT成像测量脱离稳定体积后，通过滴眼液（Celluvisc）将40ul / 100ng/ml的INFg加入眼前表面。记录不同时间点的一系列三维OCT图像。在观察的第一个小时内，在眼前表面添加INFg导致视网膜脱离体积显著迅速减少50%。这一结果与体外观察到的RPE细胞液体转运增加一致。我们假设在正常的RPE细胞中，这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通路的其他调控靶点包括微RNA 155（miR-155）、炎性体和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，这有助于构成炎性体的激活。调节IL-18和IFNg水平可能导致逆转葡萄膜炎相关病理改变的治疗效果。

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.