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

描述（由申请人提供）：本申请的广泛、长期目标是从分子角度定义外视网膜中蛋白质氧化修饰、免疫系统识别和外视网膜易受攻击之间的联系，从而导致潜在的年龄相关性黄斑变性（AMD）的疾病过程。在上一个资助期间完成的工作表明，AMD眼部组织含有高水平的蛋白质，这些蛋白质被长链多不饱和脂肪酸二十二碳六烯酸（DHA）的氧化片段内聚修饰。许多被这种和其他加合物修饰的蛋白质在drusen和Bruch膜中被发现。此外，针对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）中比在年龄匹配的非AMD患者中更丰富。根据这些结果，出现了以下关于AMD的初始刺激的假设：(a)。由于光感受器- rpe复合物中含有高浓度的DHA，再加上DHA易受氧化损伤，cep -加合物随着时间的推移在外层视网膜中缓慢生成，(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Bruch膜- rpe界面补体攻击途径的激活，以响应外视网膜组织中CEP表位的持续生成。为了验证这一假设，我们用cep内聚的小鼠血清白蛋白免疫正常小鼠。我们的预测是，CEP系统免疫会使小鼠对正常衰老过程中外视网膜产生的内源性CEP内聚蛋白敏感。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。对这些小鼠的分析表明，RPE和光感受器的局灶性病变类似于地理萎缩，这是与干性AMD相关的致盲终末期萎缩。这种新的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因子遗传缺陷的小鼠。一种新的小鼠AMD模型将为用于预防或限制AMD进展的治疗方法的临床前测试提供重要的新资源。

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.