The Mechanism of the Outer Blood-Retina Barrier Breakdown

外层血视网膜屏障破坏的机制

• 批准号: 8142792
• 负责人: Zsolt Ablonczy
• 金额: $ 35.4万
• 依托单位: MEDICAL UNIVERSITY OF SOUTH CAROLINA
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-30 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8142792
• 关键词: Advanced Glycosylation End Products; Aging; Alzheimer' s Disease; Angiography; Apical; Biological; Blindness; Blood; Blood Vessels; Choroid; Country; Data; Development; Diabetes Mellitus; Digestion; Disease; Edema; Endogenous Factors; Environment; Environmental Risk Factor; Enzymes; Event; Excision; Extracellular Fluid; Extracellular Space; Extravasation; Eye; Eye diseases; Fluorophotometry; Gel; Growth Factor Interaction; Indium; Inflammation; Lead; Link; Liquid substance; Maintenance; Mass Spectrum Analysis; Mediating; Mitogens; Modeling; Optical Coherence Tomography; Oryctolagus cuniculus; Oxidative Stress; Peptide Hydrolases; Permeability; Physiological; Process; Production; Property; Protease Inhibitor; Proteomics; Resolution; Retina; Retinal; Retinal Diseases; Retinal Edemas; Role; Signal Transduction; Social Impacts; Source; Structure of retinal pigment epithelium; Surface; System; Tissues; Vascular Endothelial Growth Factor Receptor; Vascular Endothelial Growth Factors; base; cytokine; economic impact; in vitro testing; in vivo; neovascularization; pigment epithelium-derived factor; public health relevance; receptor; receptor for advanced glycation endproducts; research study; response; secretase

DESCRIPTION (provided by applicant): A common element in several retinal diseases is the accumulation of fluid within the extracellular space of the neurosensory retina. In its various forms, broadly-termed retinal edema is a leading cause of vision loss in Western countries. Therefore, it has an enormous social and economic impact. Initial studies concluded that the principle source of the extracellular fluid was leakage from inner retina vessels. But subsequent studies have demonstrated that alterations in the retinal pigment epithelium (RPE) also contribute to the development of retinal edema. Despite its origin, the removal of extracellular fluid from the retina is dependent on the RPE. Our long-term objective is to understand how endogenous and environmental factors influence RPE function and contribute to the development and resolution of edematous fluid. Vascular endothelial growth factor (VEGF) is required for normal vascular development in the choroid, but it is also the principle cytokine responsible for neovascularization in many proliferative eye diseases. In addition to its role as an endothelial mitogen, VEGF regulates retinal vasculature and RPE permeability as well. Several studies have shown that anti-VEGF therapies are efficacious in treating not only proliferative disorders within the eye, but also retinal edema. The RPE is a primary source of VEGF in the eye. We and others have shown that oxidative stress not only enhances VEGF secretion, but directs most of this new VEGF toward the apical RPE surface. This increase in VEGF at the apical surface of the RPE can alter the barrier function and secretory properties of the tissue. The actions of VEGF are antagonized by pigment-epithelium-derived factor (PEDF), secreted by the RPE at the apical surface. We have recently shown that a central component of the anti-VEGF actions of PEDF in the RPE is the ectodomain shedding of VEGF-R2 by a mechanism requiring the activation of g- secretase. Based on these data, we hypothesize that oxidative stress suppresses the juxtamembrane protease system required for normal RPE function. This hypothesis links oxidative stress to the early events in the development of retinal edema. When the juxtamembrane proteolytic activity declines (i.e., diabetes, aging, or inflammation) in response to a reduced PEDF to VEGF ratio, VEGF-R2 stability and activity are enhanced, disrupting RPE function and leading to the development of edema and eventual vision loss. This application proposes three Aims to investigate how oxidative stress, receptor dynamics, and specific proteolytic systems interact to modulate RPE function and the development of retinal edema. We will primarily use oxidative stress and PEDF/VEGF interactions to model these events, but a limited number of experiments are proposed to investigate the shedding of the advanced glycation end-product receptor (RAGE). Aim 1 will determine the effects of PEDF on oxidative-stress- and VEGF-mediated RPE breakdown, Aim 2 will characterize the PEDF- stimulated VEGF- and RAGE-receptor processing by juxtamembrane proteases, and Aim 3 will elucidate the consequences of juxtamembrane protease inhibition in vivo. PUBLIC HEALTH RELEVANCE: PEDF antagonizes the oxidative-stress-induced, VEGF-mediated breakdown of the outer blood-retina barrier through the stimulation of juxtamembrane proteases. Therefore, when the PEDF to VEGF ratio is reduced (e.g., in oxidative stress, during diabetes or aging) protease activity declines, enhancing VEGF signaling, which leads to the disruption of RPE function and eventual retinal edema. The involvement of PEDF/juxtamembrane proteases in the maintenance of RPE function is intriguing and can potentially link the vision loss associated with diabetes, aging, AMD, and Alzheimer disease, as well as provide a convenient way to detect and pharmacologically control the development and resolution of retinal edema.

描述（由申请人提供）：几种视网膜疾病中的一个常见元素是流体在神经感觉视网膜的细胞外空间内的积累。以各种形式，广泛的视网膜水肿是西方国家视力丧失的主要原因。因此，它具有巨大的社会和经济影响。初步研究得出的结论是，细胞外液的主要来源是内部视网膜血管泄漏。但是随后的研究表明，视网膜色素上皮（RPE）的改变也有助于视网膜水肿的发展。尽管其起源是从视网膜中去除细胞外流体取决于RPE。我们的长期目标是了解内源性和环境因素如何影响RPE功能，并有助于水肿流体的发展和解决。血管内皮生长因子（VEGF）是正常血管发育所必需的，但它也是许多增殖性眼部疾病中负责新血管化的主要细胞因子。 VEGF除了作为内皮有丝分裂原的作用外，还调节视网膜脉管系统和RPE渗透性。几项研究表明，抗VEGF疗法不仅可以治疗眼睛内的增殖性疾病，而且可以治疗视网膜水肿。 RPE是眼睛中VEGF的主要来源。我们和其他人表明，氧化应激不仅可以增强VEGF的分泌，而且将大部分新VEGF引导到顶端RPE表面。 RPE顶端表面VEGF的增加可以改变组织的屏障功能和分泌特性。 VEGF的作用是由RPE在顶部表面分泌的色素上皮衍生因子（PEDF）的。我们最近表明，PEDF在RPE中的抗VEGF作用的核心部分是通过需要激活G-分泌酶的机制对VEGF-R2的脱落域脱落。基于这些数据，我们假设氧化应激抑制了正常RPE功能所需的近膜蛋白酶系​​统。该假设将氧化应激与视网膜水肿发展的早期事件联系起来。当对PEDF与VEGF比率降低的近去膜蛋白水解活性下降（即糖尿病，衰老或炎症）时，VEGF-R2的稳定性和活性会增强，破坏RPE功能并导致水肿发展和最终视觉丧失。该应用提出三个旨在研究氧化应激，受体动力学和特定蛋白水解系统如何相互作用以调节RPE功能和视网膜水肿的发展。我们将主要使用氧化应激和PEDF/VEGF相互作用来对这些事件进行建模，但是提出了有限的实验来研究晚期糖基化终产物受体（RAGE）的脱落。 AIM 1将确定PEDF对氧化应激和VEGF介导的RPE分解的影响，AIM 2将通过近膜蛋白酶的pEDF刺激的VEGF和愤怒受体的处理来表征PEDF刺激的VEGF和RAGE受体处理，而AIM 3将阐明juxtammbrane蛋白酶蛋白酶蛋白酶抑制InVivo的后果。 公共卫生相关性：PEDF通过刺激叶膜蛋白酶来拮抗氧化压力诱导的，VEGF介导的外部血液 - 逆转录屏障的分解。因此，当PEDF与VEGF比率降低时（例如，在氧化应激，糖尿病或衰老期间）蛋白酶活性下降时，增强了VEGF信号传导，从而导致RPE功能的破坏和最终的视网膜水肿。 PEDF/juxtammbrane蛋白酶参与RPE功能的维持很有趣，并且可以潜在地将与糖尿病，衰老，AMD和阿尔茨海默氏病有关的视力损失联系起来，并提供了一种方便的检测和药理学方法，可以控制和药理控制视网膜水肿的发展和分辨率。