The Pathomechanistic Role of Endothelial IDO in proliferative Retinopathy

描述（由申请人提供）：增殖性视网膜病变（PR），包括早产儿视网膜病变（ROP）和增殖性糖尿病视网膜病变（DR），是儿童和工作年龄成人失明的主要原因。尽管PR以病理性视网膜血管过度增生或新生血管为特征，但针对特异性抑制血管内皮生长因子（VEGF）产生的治疗未能持续改善临床结果。这一观察结果清楚地表明，额外的分子因素/途径有助于PR的病理性视网膜新生血管，因此可能是可行的治疗靶点。在这方面，我们对我们的初步发现很感兴趣，即在DR患者的玻璃体中存在强的吲哚胺-2,3-双加氧酶（IDO）表达，以及在氧诱导视网膜病变（OIR）小鼠幼崽的视网膜新生血管内皮中也存在。此外，在体外实验中，我们发现IDO的上调使血管内皮细胞（ECs）具有独立于VEGF的增殖、迁移和成管能力增强。根据这些新发现，我们假设内皮细胞IDO具有促血管生成活性，并且这种酶的靶向抑制将阻断PR的病理视网膜血管生成/新生血管。为了验证这一假设，我们将使用一些独特的方法。其中包括一个稳定的IDO过表达的视网膜血管EC系和睡美人（SB）为基础的非病毒基因整合策略，能够在体内视网膜EC内长期表达人IDO （hIDO）转基因。在具体目标1中，我们将评估内皮细胞的促血管生成活性

DESCRIPTION (provided by applicant): Proliferative retinopathy (PR), which includes retinopathy of prematurity (ROP) and proliferative diabetic retinopathy (DR), represent a leading cause of blindness in both children and working-age adults. Although PR is characterized by pathological retinal vascular overproliferation or neovascularization, therapies aimed at specifically inhibiting production of vascular endothelial growth factor (VEGF) have failed to consistently improve clinical outcomes. This observation clearly indicates that additional molecular factors/pathways contribute to pathological retinal neovascularization in PR and may thus be viable therapeutic targets. In this regard, we became intrigued by our preliminary finding that strong indoleamine-2,3-dioxygenase (IDO) expression is present in the vitreous of patients with DR as well as in the endothelium of retinal neovessels from mouse pups undergoing oxygen-induced retinopathy (OIR). Further, in in vitro experiments, we found that up-regulation of IDO endows the vascular endothelial cells (ECs) with enhanced capacity for proliferation, migration and tube formation independently of VEGF. In light of these novel findings we hypothesize that that endothelial IDO possesses pro-angiogenic activity, and that targeted inhibition of this enzyme will block the pathological retinal angiogenesis/neovascularization in PR. To test this hypothesis, we will use a number of unique approaches, which include a stable IDO-overexpressing retinal vascular EC line and the Sleeping- Beauty (SB)-based nonviral gene integrating strategy capable of long-lasting human IDO (hIDO) transgene expression within retinal ECs in vivo. In Specific Aim 1, we will evaluate the pro-angiogenic activity of endothelial IDO in vitro and in vivo, with a focus on the the molecular mechanism(s) behind IDO-induced phenotypic switching of retinal ECs from a normal to a pro-angiogenic state. In Specific Aim 2, we will examine the therapeutic potential of pharmacological inhibition of retinal endothelial IDO in the prevention of experimental PR. In these studies, we seek to achieve the therapeutic goal using selective IDO inhibitor 1-metheyl-DL-tryptophan (1-mT), a small molecular chemical (molecular weight 218) that can be orally or intraperitoneally administered and is currently used in anti-cancer clinical trials with satisfactory safety profile. Taken together, this proposal addresses a critical scientific gap in the treatment of PR, and if proven effective, may be fast-tracked to a phase 1 clinical trial.