Initiating Events in AMD: a mouse model for the human disease

描述（由申请人提供）：视网膜相关性黄斑变性（AMD）是老年人的一种祸害，在美国，大约三分之一的75岁以上的人患有这种可能致盲的疾病。有大量证据表明AMD是一种涉及补体途径失调的炎性疾病。我们发现，半抗原，CEP（羧乙基吡咯），产生的氧化损伤二十二碳六烯酸（DHA），是目前作为一个加合物的玻璃疣蛋白在AMD供体的眼睛。此外，抗CEP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。由于DHA在视网膜外层丰富，在那里光和高氧水平为氧化损伤提供了允许的环境，该组织可能是CEP加合物的来源。由于CEP加合物是抗原性的，我们推测，当外层视网膜产生这些加合物时，免疫系统对这些新的表位产生反应，并随着时间的推移开始攻击作为该片段来源的细胞。为了验证这一假设，我们用CEP加合的小鼠血清白蛋白（CEP-MSA）免疫正常小鼠。我们的预测是，全身免疫与CEP会敏感的小鼠内源性CEP加合物产生的外视网膜在正常的过程中的老化。反过来，免疫系统将通过攻击最容易产生CEP表位的细胞来做出反应。我们发现，免疫小鼠产生CEP抗体，将补体成分-3固定在布鲁赫膜上，在衰老过程中在RPE下方积累玻璃疣，并在RPE中产生类似地图状萎缩的病变，这是干性AMD的终末期特征。本文提出的研究使用该小鼠模型对补体激活途径在产生病理中的作用、抗体在引起观察到的病变中的作用以及通过操纵补体激活或口服耐受抑制病理来预防病变的可能性进行机制研究。这些研究的结果有可能导致识别新的治疗途径来预防AMD。

DESCRIPTION (provided by applicant): Age-related macular degeneration (AMD) is a scourge of the elderly, with some stage of this potentially blinding disease present in approximately a third of individuals over 75 years of age in the US. There is substantial evidence that AMD is an inflammatory disease involving dysregulation of the complement pathway. We found that the hapten, CEP (carboxyethylpyrrole), generated by oxidative damage to docosahexaenoic acid (DHA), is present as an adduct on drusen proteins in AMD donor eyes. In addition, autoantibodies against CEP were more abundant in the circulation (plasma) of individuals with AMD than in age-matched individuals without AMD. Because DHA is abundant in the outer retina where light and high oxygen levels provide a permissive environment for oxidative damage, this tissue is a likely source of CEP-adducts. Since CEP-adducts is antigenic, we speculated that as the outer retina generates these adducts, the immune system becomes responsive to these new epitopes and over time begins to attack the cells that are the source of this fragment. To test this hypothesis we immunized normal mice with CEP-adducted mouse serum albumin (CEP-MSA). Our prediction was that systemic immunization with CEP would sensitize mice to endogenous CEP-adducts 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. We found that immunized mice develop antibodies to CEP, fix complement component-3 in Bruch's membrane, accumulate drusen below the RPE during aging, and develop lesions in the RPE mimicking geographic atrophy, the end-stage condition characteristic of dry AMD. The research proposed here uses this mouse model for mechanistic studies on the role of complement activation pathways in producing the pathology, the role of antibody in causing the lesions observed, and the possibility of prevention of the lesions through manipulation of complement activation or suppression of the pathology with oral tolerance. Outcomes from these studies have the potential to lead to the identification of new therapeutic pathways to prevent AMD.