The role and mechanisms of lipofuscin formation in macular degeneration

描述(申请人提供)：这项研究的总体目标是更好地了解眼部脂褐素在黄斑变性中的作用。为此，我们开发了临床上相关的方法来抑制脂褐素的形成(作为对黄斑变性的可能干预)，并建立了脂褐素诱导的黄斑变性的动物模型。这一应用的具体目的是：1)阐明脂褐素与视网膜健康的关系和脂褐素形成的机制：a)确定减缓脂褐素生物合成是否可以防止黄斑变性啮齿动物模型的眼睛衰老和视力丧失；b)确定增加RPE中维生素A二聚体的浓度是否会导致脂褐素颗粒和玻璃体的形成；以及c)确定是否可以通过迅速增加脂褐素色素来产生黄斑变性动物模型；以及目的2)阐明眼睛中维生素A和维生素A二聚体的药代动力学：a)确定维生素A在外节中交换为维生素A D3-A所需的时间；B)确定维生素A二聚体的RPE半衰期；c)确定脂褐素色素的生物合成速率是否随年龄增加或脂褐素色素本身是否随年龄“积累”；以及d)比较维生素A和D3-维生素A的视觉循环动力学。我们将通过使用我们实验室开发的新方法减缓或加快动物体内脂褐素的形成来实现这些特定目标，并将眼睛健康与脂褐素浓度相关联。在评估眼部对脂褐素变化的反应时，我们使用标准方法，如组织组织学、眼底自发荧光、视网膜电信号测量、炎症状态和维生素A二聚体的定量。为了阐明维生素A及其二聚体的眼部药代动力学，我们使用氚或氚标记物种来跟踪它们的命运和/或生物合成。我们打算证明，维生素A二聚体(也称为脂褐素色素或A2E和ATR-二聚体)的生物合成是眼睛RPE细胞层中脂褐素颗粒(或沉积)形成的早期和关键步骤；脂褐素颗粒导致玻璃体(或玻璃体样物质)的形成，最终导致细胞死亡和视力损害。我们打算证明，停止维生素A二聚体的生物合成是阻止脂褐素和玻璃体形成的有效临床策略，作为阻止最常见形式的黄斑变性进展的一种方法。我们打算收集证据表明，服用D3-维生素A是一种安全、实用的方法，可以防止几种形式的黄斑变性的进展。

DESCRIPTION (provided by applicant): The overall goal of this research is to better understand the role of ocular lipofuscin in macular degeneration. In doing so we develop clinically relevant ways to inhibit lipofuscin formation (as possible interventions for macular degeneration) and develop animal models of lipofuscin-induced macular degeneration. The specific aims of this application are: AIM 1) elucidate the relationship between lipofuscin and retinal health and the mechanism of lipofuscin formation: a) determine whether slowing lipofuscin biosynthesis can prevent ocular aging and vision loss in rodent models of macular degeneration; b) determine whether increasing the concentration of vitamin A dimers in the RPE leads to the formation of lipofuscin granules and drusen; and c) determine whether animals models of macular degeneration can be generated by rapidly increasing lipofuscin pigments; and AIM 2) elucidate pharmacokinetics vitamin A and vitamin A dimers in the eye: a) determine the time it takes to swap vitamin A for D3-vitamin A in the outer segments; b) establish the RPE half life of vitamin A dimers; c) determine whether the rate of lipofuscin pigment biosynthesis increases with age or whether lipofuscin pigments themselves "accumulate" with age, and; d) compare visual cycle kinetics of vitamin A vs. D3-vitamin A. We will achieve these specific aims by slowing down or speeding up lipofuscin formation in animals, using novel methods developed in our lab, and correlating eye health to lipofuscin concentration. In evaluating eye health in response to changes in lipofuscin we employ standard methods such as, tissue histology, fundus autofluorescence, electroretinogram measurements, inflammatory status and quantification of vitamin A dimers. For the elucidation of the ocular pharmacokinetics of vitamin A and its dimers we track their fate and/or biosynthesis using deuterium or tritium labeled species. We intend to show that the biosynthesis of vitamin A dimers (also called or lipofuscin pigments or A2E and ATR-dimer) is an early and critical step in the formation of lipofuscin granules (or deposits) in the RPE cell layer of the eye; that lipofuscin granules lead to the formation of drusen (or drusen like material) and ultimately cell death and vision impairment. We intend to show that stopping the biosynthesis of vitamin A dimers is an effective clinical strategy to stopping the formation of lipofuscin and drusen, as a method to stop the progression of the most prevalent forms of macular degeneration. We intend to gather evidence to show that the administration of D3-vitamin A is a safe, practical, method to prevent the progression of several forms of macular degeneration.