Initiating Events in AMD: An Animal Model for the Human Disease

描述(由申请人提供)：这项建议的广泛、长期目标是用分子术语定义外层视网膜中蛋白质的氧化修饰、免疫系统识别它们和外层视网膜易受攻击之间的联系，从而导致老年性黄斑变性(AMD)潜在的疾病过程。在上一次赠款期间完成的工作显示，AMD眼组织含有高水平的蛋白质，通过加入长链多不饱和脂肪酸--二十二碳六烯酸(DHA)的氧化片段进行修饰。许多被这种加合物和其他加合物修饰的蛋白质存在于玻璃样变和布鲁赫膜中。此外，抗这些独特的羧乙基吡咯加合物(CEP)的自身抗体在AMD患者的循环(血浆)中比年龄匹配的非AMD患者更丰富。从这些结果中，出现了关于AMD的起始刺激的以下假设：(A)。由于DHA在光感受器-RPE复合体中的高浓度，加上DHA对氧化损伤的脆弱性，CEP-加合物随着时间的推移在外层视网膜中缓慢产生，(B)。这些CEP加合物代表免疫系统外来的新表位，导致产生针对CEP的自身抗体。(C)。抗CEP抗体反过来参与激活Bruch膜-RPE界面的补体攻击途径，以响应外层视网膜组织中CEP表位的持续产生。为了验证这一假设，我们用CEP加成的小鼠血清白蛋白免疫正常小鼠。我们的预测是，CEP的系统免疫将使小鼠对正常衰老过程中外视网膜产生的内源性CEP加成蛋白敏感。反过来，免疫系统会通过攻击最容易产生CEP表位的细胞来做出反应。对这些小鼠的分析显示，RPE和光感受器中的局灶性病变类似于地理萎缩，即与干性AMD相关的致盲终末期萎缩。这一新的AMD小鼠模型将在正常小鼠中进一步表征，CEP免疫将扩展到补体途径分子及其调节基因缺陷的小鼠。一个新的小鼠AMD模型将是一个重要的新资源，用于预防或限制AMD进展的治疗学的临床前测试。

DESCRIPTION (provided by applicant): The broad, long-term objective of this proposal is to define in molecular terms the linkage between the oxidative modifications of proteins in the outer retina, their recognition by the immune system and the vulnerability of the outer retina to attack, leading to the disease processes underlying age-related macular degeneration (AMD). Work completed during the last grant period revealed that AMD eye tissues contain high levels of proteins modified by the adduction of oxidation fragments of the long chain polyunsaturated fatty acid, docosahexaenoic acid (DHA). Many of the proteins modified by this and other adducts are found in drusen and Bruch's membrane. Furthermore, autoantibodies against these unique carboxyethylpyrrole adducts (CEP) are more abundant in the circulation (plasma) of individuals with AMD than are found in age-matched individuals without AMD. From these results the following hypothesis has emerged regarding an initiating stimulus for AMD: (a). Because of the high concentration of DHA in the photoreceptors-RPE complex coupled with the vulnerability of DHA to oxidative damage, CEP-adducts are slowly generated over time in the outer retina, (b). These CEP-adducts represent new epitopes foreign to the immune system resulting in the generation of autoantibodies against CEP. (c). Anti-CEP-antibodies in turn are involved in activation of the complement attack pathway at the Bruch's membrane-RPE interface in response to the continued generation of CEP epitopes in tissues of the outer retina. To test this hypothesis we immunized normal mice with CEP-adducted mouse serum albumin. Our prediction was that systemic immunization with CEP would sensitize mice to endogenous CEP-adducted proteins generated in the outer retina during the normal course of aging. In turn the immune system would respond by attacking the cells where CEP epitopes are most readily generated. Analysis of these mice demonstrated focal lesions in the RPE and photoreceptors that mimic geographic atrophy, the blinding end-stage atrophy associated with dry AMD. This new mouse model for AMD will be further characterized in normal mice and the CEP-immunizations will be extended to mice with genetic defects in complement pathway molecules and their regulators. A new model for AMD in the mouse will be an important a new resource for use in the preclinical testing of therapeutics designed to prevent or limit the progression of AMD.