ANTIOXIDANT SYSTEMS AND AGE RELATED MACULAR DEGENERATION

视网膜相关性黄斑变性（ARMD）是视力的主要原因 美国老年人的损失光感受器损伤导致 ARMD患者的失明通常继发于视网膜色素损伤 上皮（RPE）细胞。 有大量的间接数据， 支持ARMD可能与氧化损伤有关的假设， 视网膜色素上皮细胞表现出疾病的早期迹象。 我们现在有数据 直接表明谷胱甘肽（GSH）是一种重要的抗氧化剂， 保护培养的人RPE细胞免受氧化损伤。此外，本发明还提供了一种方法， 初步研究表明，血浆GSH水平随着 ARMD患者可能存在较低的血浆GSH水平。 在本申请中，我们建议进一步定义GSH在以下方面的作用： 保护RPE免受氧化损伤。 两组研究将 进行评估老化和ARMD对GSH的影响：1）血液 将在没有ARMD的患者队列中测量GSH水平， 以及那些具有良好特征的ARMD的人，包括 未服用微量营养素抗氧化剂补充剂的患者，以及2）GSH 将在不同年龄的供体的眼睛中测定合成能力， 通过测量GSH合成速率和活性， γ-谷氨酰半胱氨酸合成酶 (GCS)在培养的RPE细胞中，通过测量新鲜的 尸检眼的视网膜色素上皮细胞。 将进行进一步的研究，以确定 GSH合成能力是否可以通过使用 不同的谷胱甘肽前体，激素诱导剂，或酚类抗氧化剂， 可以诱导GCS活性。 最后，机理研究将建立l） 细胞内GSH维持的改善是否导致 过氧化物消除和更好地维持细胞内 抗氧化剂、抗坏血酸盐和α-生育酚，以及2）是否外源GSH 可以通过防止破坏两个关键的质膜运输来保护 Na ~+，K ~+-ATP酶和Ca ~（2+）-ATP酶。 这些研究的结果将提供关键数据，以帮助我们 了解ARMD的发病机制，并提供平台 用于未来的治疗。

Age-related macular degeneration (ARMD) is the leading cause of vision loss in elderly Americans. The photoreceptor damage that results in blindness in ARMD is usually secondary to injured retinal pigment epithelial (RPE) cells. There is substantial circumstantial data to support the hypothesis that ARMD may be related to oxidative injury and that RPE cells exhibit early signs of the disease. We now have data directly showing glutathione (GSH) to be an important antioxidant capable of protecting cultured human RPE cells from oxidative injury. In addition, preliminary studies demonstrate that plasma levels of GSH decrease with age and that there may be lower plasma GSH levels in ARMD patients. In this application, we propose to further define the role of GSH in protection of the RPE from oxidative injury. Two groups of studies will be performed to evaluate the effects of aging and ARMD on GSH: l) blood levels of GSH will be measured in a cohort of patients without ARMD as well as those with well characterized ARMD, including a sub-population of patients not taking micronutrient antioxidant supplementation, and 2) GSH synthetic capacity will be determined in eyes of donors of varying ages, with and without ARMD by measuring the rate of GSH synthesis and activity of the enzyme catalyzing GSH synthesis, gamma-glutamycysteine synthetase (GCS), in cultured RPE cells, and by measurement of mRNA for GCS in fresh RPE from autopsy eyes. Further studies will be performed to determine whether GSH synthetic capacity can be manipulated therapeutically using different GSH precursors, hormonal inducers, or phenolic antioxidants that may induce GCS activity. Finally, mechanistic studies will establish l) whether improved maintenance of intracellular GSH leads to increased peroxide elimination and better maintenance of the intracellular antioxidants, ascorbate and alpha-tocopherol, and 2) whether exogenous GSH can protect by preventing damage to two critical plasma membrane transport systems, Na+,K+ATPase and Ca2+-ATPase. The results of these studies will provide critical data to help in our understanding of the pathogenesis of ARMD and could provide the platform for future therapies.