Prevention of Retinal Degeneration by Crystallins in Experimental Uveitis

晶状体蛋白预防实验性葡萄膜炎中的视网膜变性

基本信息

批准号：
8128483
负责人：
NARSING A RAO
金额：
$ 37.04万
依托单位：
DOHENY EYE INSTITUTE
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-09-01 至 2014-08-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by principal investigator): Intraocular inflammation, commonly referred to as uveitis, is a leading cause of blindness from retinal photoreceptor cell apoptosis. A robust animal model of uveitis that closely resembles human uveitis is experimental autoimmune uveoretinitis (EAU). It is characterized by two phases: the early phase, 5-7 days postimmunization (p.i.) with an uveitogenic antigen, and the late/amplification phase, 12-14 days p.i. During the late phase, macrophages/neutrophils infiltrate the retina, and photoreceptor damage is noted histologically. The early phase, preceding the leukocyte infiltration, reveals Th1- and Th17-driven cytokines in the retina, nitration of cytochrome c (cyto c) in the photoreceptors from mitochondrial oxidative stress, and the release of nitrated cyto c into the cytosol. Such cyto c release is known to cause apoptosis. However, apoptosis is not a feature of early EAU, suggesting the presence of a protective mechanism(s) in the EAU retina that prevents photoreceptor apoptosis. Current preliminary studies suggest that the protection is offered by 1A crystallin upregulation and that this is unique to the photoreceptors and are not mediated by well-recognized anti-apoptotic proteins, including 1B crystallin, heat shock protein 27 and other heat shock proteins. Significantly, 1A crystallin knockout mice with early EAU show prominent apoptosis in the retina; such apoptosis is totally absent in the wild type mice with EAU. The data reveal the significance of 1A crystallin in preventing apoptosis in the retina. Moreover, it indicates that unlike other tissues, the photoreceptors utilize 1A crystallins selectively in the prevention of oxidative stress-mediated damage in early EAU, a novel protective mechanism observed in the photoreceptors. Based on our preliminary studies we hypothesize that 1) upregulation of 1A crystallin is a feature of the photoreceptors in response to mitochondrial oxidative stress; 2) upregulated 1A crystallin interacts with the oxidative stress-induced nitrated cyto c, blocking the activation of caspases, and preventing apoptosis of photoreceptors. These hypotheses will be tested by three specific aims: 1) Determine the immune mechanism of 1A crystallin upregulation in the retina during EAU; 2) Determine prevention of photoreceptor apoptosis by 1A crystallin in EAU and 3) Determine photoreceptor oxidative stress induction by iNOS in EAU. In-depth analysis of the immune mechanism(s) of 1A crystallin upregulation in EAU and its protective anti- apoptotic function will enhance our understanding, by clarifying the importance of crystallin upregulation in photoreceptor protection not only in uveitis, but in other oxidative stress-mediated retinal degenerations as well. Moreover the current proposal suggests that 1A crystallin can be a promising therapeutic agent for preventing oxidative stress-mediated photoreceptor damage. Such oxidative damage has been implicated in various blinding diseases, including age-related macular degeneration, retinal vein occlusion, and glaucoma. PUBLIC HEALTH RELEVANCE AlphaA crystallin is a unique protein present in the eye and other tissues. Lack of this protein can cause blindness, and supplement of this protein can prevent several blinding diseases.

描述（由主要研究者提供）：眼内炎症，通常称为葡萄膜炎，是视网膜感光细胞凋亡导致失明的主要原因。实验性自身免疫性葡萄膜视网膜炎（EAU）是一种与人类葡萄膜炎非常相似的强大葡萄膜炎动物模型。其特征为两个阶段：早期阶段，即用致葡萄膜抗原进行免疫后 5-7 天，以及晚期/扩增阶段，即接种后 12-14 天。在后期，巨噬细胞/中性粒细胞浸润视网膜，并在组织学上观察到光感受器损伤。在白细胞浸润之前的早期阶段，揭示了视网膜中 Th1 和 Th17 驱动的细胞因子、线粒体氧化应激导致光感受器中细胞色素 c (cyto c) 的硝化，以及硝化细胞 c 释放到细胞质中。已知这种细胞c释放会引起细胞凋亡。然而，细胞凋亡并不是早期 EAU 的一个特征，这表明 EAU 视网膜中存在防止光感受器细胞凋亡的保护机制。目前的初步研究表明，这种保护是由 1A 晶状体蛋白上调提供的，这是光感受器所独有的，并且不是由公认的抗凋亡蛋白（包括 1B 晶状体蛋白、热休克蛋白 27 和其他热休克蛋白）介导的。值得注意的是，早期 EAU 的 1A 晶状体蛋白基因敲除小鼠在视网膜中表现出显着的细胞凋亡。这种细胞凋亡在患有 EAU 的野生型小鼠中完全不存在。这些数据揭示了 1A 晶状体蛋白在预防视网膜细胞凋亡方面的重要性。此外，它表明与其他组织不同，光感受器选择性地利用 1A 晶状体蛋白来预防早期 EAU 中氧化应激介导的损伤，这是在光感受器中观察到的一种新的保护机制。根据我们的初步研究，我们假设 1) 1A 晶状体蛋白上调是光感受器响应线粒体氧化应激的一个特征； 2）上调的1A晶状体蛋白与氧化应激诱导的硝化细胞c相互作用，阻断半胱天冬酶的激活，防止光感受器凋亡。这些假设将通过三个具体目标进行检验：1）确定EAU期间视网膜中1A晶状体蛋白上调的免疫机制； 2) 确定 EAU 中 1A 晶状体蛋白对光感受器凋亡的预防作用，以及 3) 确定 EAU 中 iNOS 诱导光感受器氧化应激的作用。深入分析 EAU 中 1A 晶状体蛋白上调的免疫机制及其保护性抗凋亡功能，将通过阐明晶状体蛋白上调不仅在葡萄膜炎中而且在其他氧化应激中对光感受器保护的重要性来增强我们的理解。介导的视网膜变性也是如此。此外，目前的提议表明，1A 晶状体蛋白可以成为预防氧化应激介导的光感受器损伤的有前途的治疗剂。这种氧化损伤与多种致盲疾病有关，包括年龄相关性黄斑变性、视网膜静脉阻塞和青光眼。公共健康相关性 AlphaA 晶状体蛋白是一种存在于眼睛和其他组织中的独特蛋白质。缺乏这种蛋白质会导致失明，补充这种蛋白质可以预防多种致盲性疾病。