Therapeutic Effect of a Novel Antioxidant on Degenerative Eye Disorders

描述（由申请人提供）：拟议的研究将在相关动物模型中测试一种新型巯基抗氧化剂N-乙酰半胱氨酸酰胺（NACA）滴眼液配方在预防和治疗白内障和视网膜变性方面的有效性。本申请的广泛、长期目标是开发一种用于治疗与年龄有关的眼病（AREDs）的NACA滴眼液配方，并为进一步探索治疗各种与年龄有关的疾病的药理学抗氧化方法提供动力。氧化应激损伤在AREDs发病机制中的重要性已经在白内障和干型老年性黄斑变性（AMD）中得到证实。晶状体和黄斑都受到明显的光氧化应激，而黄斑是代谢活性高和存在多不饱和脂肪浓度的部位。晶状体和视网膜细胞通过产生足够的抗氧化酶或像谷胱甘肽（GSH）这样的小分子抗氧化剂来对抗氧化应激。它们产生这种抗氧化剂的能力随着年龄的增长而下降，导致氧化损伤增加。在晶状体中，其结果是晶体蛋白溶解度逐渐降低，表现为晶状体混浊。在视网膜中，它导致线粒体损伤和干性AMD特征的积水。抗氧化剂如N-乙酰半胱氨酸（NAC）已显示出改善氧化应激损伤的希望。我们的数据表明，作为一种稳定的NAC药物类似物，NACA在降低氧化应激方面的效果比NAC好得多。初步的动物研究表明，腹腔内注射NACA可减少白内障的形成，而将NACA应用于视网膜上皮细胞可防止细胞活力丧失。建议的具体目的

DESCRIPTION (provided by applicant): The proposed research will test the effectiveness of an eye drop formulation of a new thiol antioxidant, N- acetylcysteine amide (NACA), in preventing and treating cataracts and retinal degeneration in relevant animal models. This application's broad, long-term objectives are to develop an eye drop formulation of NACA for treatment of age-related eye diseases (AREDs) and to provide impetus for greater exploration of pharmacologic antioxidant approaches to the treatment of a variety of age-related diseases. The importance of oxidative stress damage in the pathogenesis of AREDs has been established for cataracts and the dry form of age-related macular degeneration (AMD). The lens and macula are both subjected to significant photo-oxidative stress, while the macula is the site of high rate of metabolic activity and the presence of concentrations of polyunsaturated fats. Lens and retinal cells combat oxidative stress by generating sufficient antioxidant enzymes or small molecular weight antioxidants like glutathione (GSH). Their ability to produce such antioxidants decreases with age, leading to increased oxidative damage. In the lens, the result is a progressive reduction in solubility of crystalline proteins that manifests in an opacification of te lens. In the retina, it results in mitochondrial damage and the accumulation of drusen that characterizes dry AMD. Antioxidants like N- acetyl cysteine (NAC) have shown promise in ameliorating oxidative stress damage. Our data indicates that a stable pharmaceutical analogue of NAC, NACA works much better than NAC in reducing oxidative stress. Preliminary animal studies have shown that intraperitoneal NACA reduces cataract formation while application of NACA to retinal epithelial cells prevents loss of cell viability. The Specific Aims of the proposed research are to evaluate 1) cataract formation in male Wistar rat pups receiving selenite injections and 2) retinal degeneration in rd10+/+ and Ccl2-/- mice that spontaneously develop progressive photoreceptor cell death either early (rd10+/+) or later (Ccl2-/-). We will also use a chemically-induced model, in which sodium iodate will be injected into C57/BL6 mice to induce RPE degeneration. The protective effects of NACA will be assessed in animal models by staging cataracts and measuring opacity indices in various experimental groups, while in the rd10+/+ and Ccl2-/- mice the protective effects of NACA will be assessed by measuring the visual potential and photoreceptor function based on measurements of outer nuclear layer (ONL) density and rod and cone electroretinograms (ERGs). In all animal models, we will assess the antioxidant effects of NACA by removing the target tissue (lens or retina) and measuring a number of oxidative stress parameters, the activities of antioxidant enzymes, and the expression of pro-apoptotic and apoptotic proteins such as cytochrome c and caspases. We will also study protein oxidation of crystallins, lipid peroxidation, and protein bound GSH and cysteine. PUBLIC HEALTH RELEVANCE: The loss of vision from age-related eye diseases now affects over 30 million people in the United States-a number that is expected to double in the coming decades. Diseases such as cataracts and age-related macular degeneration significantly affect quality of life and represent sizable medical costs. The annual total outlay for cataract surgery each year in the U.S. is over $9 billion while the total costs of all services related to such visin problems is over $20 billion. Several experiments show that an antioxidant called N-acetylcysteine amide (NACA) may delay the onset or halt the progression of these types of diseases. This research will test whether NACA in eye drop form can prevent and treat eye diseases such as cataracts and macular degeneration in animal models. Successful results from this study will support the advance of this medication into human use. NACA eye drops would represent an alternative to costly cataract surgery, reduce health care costs related to age-related eye diseases and greatly improve the quality of life of people affected by these diseases.