AGE-induced Phenotype of the Retinal Pigment Epithelium

描述(由申请人提供)：老年性黄斑变性(AMD)是美国后天性失明的主要原因。早期疾病患者的预防和治疗选择有限且无效。为了解决这一缺陷，这项建议将重点放在早期疾病的机制上。有证据表明，视网膜色素上皮(RPE)和Bruch膜的老化是遗传和环境影响累积的结果。这些变化有助于为AMD的发展奠定基础。在从“正常”衰老过渡到AMD的许多细胞和生化变化中，关键因素包括：i)RPE的凋亡，ii)载脂蛋白B100脂蛋白的积聚和Bruch膜的基底沉积，以及iii)补体介导的炎症。更透彻地了解这些过程的生物学和相互关系，不仅将为早期AMD的发病机制提供洞察力，也将为治疗干预提供靶点。我们之前的资助阶段专注于晚期糖基化终产物(AGEP)，它是由基质中一系列非酶糖基化反应形成的交联链，如何改变RPE-Bruch膜的表型。这些研究的信息帮助我们形成了下列相互关联的假说：i)与衰老相关的脂在RPE中的积聚刺激脂蛋白的分泌，如果过度的话，细胞凋亡，ii)与衰老相关的改变(即AGEP交链)到Bruch膜促进脂蛋白的保留和修饰，以及iii)修饰的脂蛋白诱导补体激活，这反过来又有助于细胞凋亡和基础沉积。我们的总体战略是利用多学科方法产生的协同效应，该方法将使用体外实验、转基因小鼠和人类组织病理学相关性来解决我们的假设，具体目标如下：1)确定脂肪酸堆积是否刺激RPE的脂蛋白分泌，以及如果分泌途径超载，脂肪酸堆积是否导致RPE细胞凋亡。2.)确定i)Bruch膜中脂蛋白的来源，以及ii)Bruch膜与晚期糖基化终产物(AGEP)相关的变化是否促进脂蛋白保留。3.)确定滞留的脂蛋白是否诱导补体介导的炎症，以及这是否与RPE细胞凋亡和基底沉积形成有关。

DESCRIPTION (provided by applicant): Age-related macular degeneration (AMD) is the leading cause of acquired blindness in the United States. Patients with early disease suffer from limited and ineffective options for prevention and treatment. To address this shortcoming, this proposal focuses on the mechanisms underlying early disease. Evidence suggests that aging of the retinal pigmented epithelium (RPE) and Bruch membrane is the result of accumulated genetic and environmental influences. These changes help to set the stage for the development of AMD. Among the many cellular and biochemical changes associated with the transition from "normal" aging to AMD, critical factors include i) apoptosis of the RPE, ii) accumulation of apolipoprotein B100 lipoproteins and basal deposits in Bruch membrane, and iii) complement-mediated inflammation. A more thorough understanding of the biology and relationship between these processes will not only provide insights into the mechanisms of early AMD, but also targets for therapeutic intervention. Our previous funding period focused on how advanced glycation endproducts (AGEP), cross-links formed by a series of nonenzymatic glycation reactions in the matrix, altered the RPE-Bruch membrane phenotype. Information from these investigations has helped us formulate the following inter-related hypotheses: i) aging-related lipid accumulation in the RPE stimulates lipoprotein secretion, and if excessive, apoptosis, ii) aging-related changes (i.e. AGEP cross-links) to Bruch membrane promote lipoprotein retention and modification, and iii) modified lipoproteins induce complement activation which in turn, contributes to apoptosis and basal deposits. Our overall strategy is to take advantage of the synergy that results from a multidisciplinary approach that will use in vitro experiments, genetically modified mice, and human histopathologic correlation to address our hypotheses with the following specific aims: 1.) Determine whether fatty acid accumulation stimulates lipoprotein secretion by the RPE, and if the secretion pathway is overloaded, whether fatty acid accumulation leads to RPE apoptosis. 2.) Determine i) the origin of lipoproteins in Bruch membrane, and ii) whether advanced glycation endproduct (AGEP)-related changes to Bruch membrane promote lipoprotein retention. 3.) Determine whether retained lipoproteins induce complement mediated inflammation and whether this is linked to RPE apoptosis and basal deposit formation.