A new pathogenic mechanism for diabetic retinopathy

项目摘要/摘要 糖尿病引起的视网膜氧化应激和慢性炎症在糖尿病的发病机制中起关键作用 视网膜病变(DR)。线粒体功能障碍和损伤已被确定为主要原因 过氧化体增殖物激活受体α(PPARα)是一种激素- 激活受体和转录因子。已知的是调节脂质代谢，因此，pparα激动剂 临床上用于治疗高脂血症。最近，两项独立的、前瞻性的临床研究报告说 令人惊讶的发现，口服非诺贝特，一种PPARα激动剂，对糖尿病有很强的治疗效果。 在2型糖尿病患者中。在之前的资助期，我们已经成功地证明了治疗 非诺贝特对DR的作用是通过PPARα依赖机制实现的。我们已经表明PPARα已关闭- 在糖尿病人和糖尿病动物模型的视网膜中进行调节，PPARα具有保护作用 我们已经证明，PPARα基因敲除(KO)加剧，而非诺贝特激活PPARα 减轻糖尿病视网膜病变模型中的视网膜氧化应激和视网膜炎症。这项提案将延长这些 研究并阐明PPARα保护作用的机制。我们的初步研究 显示非诺贝特治疗减少糖尿病诱导的无细胞毛细血管形成和周细胞丢失 视网膜。此外，海马分析表明，PPARαKO导致了线粒体功能障碍。 视网膜和初级周细胞。此外，PPARα-/-视网膜显示线粒体DNA(MtDNA)拷贝减少 数字，表明线粒体生物发生和/或DNA修复受损。这个项目将解决一部小说 假设糖尿病引起的PPARα表达下调至少在一定程度上是 糖尿病引起的线粒体功能障碍导致视网膜氧化应激和炎症 将决定是否PPARαKO加重，而PPARα过度表达缓解，线粒体功能障碍 (基础OCR、最大OCR和ATP产生)和线粒体DNA损伤以及视网膜氧化应激， 糖尿病小鼠视网膜白血球淤滞、血管渗漏、无细胞毛细血管形成和周细胞脱落。 我们还将确定周细胞中PPARα缺陷对糖尿病诱导的线粒体的影响 周细胞特异性条件性PPARαKO小鼠和 初级PPARα-/-周细胞。我们还将研究PPARα是否调节线粒体的生物发生和功能 通过SIRT1KO小鼠和原代SIRT1-/-周细胞的SIRT1/PGC-1α途径。 这些研究将阐明导致线粒体损伤的新的致病机制和 DR的氧化应激，并为DR揭示了一种新的治疗策略。这些研究也将有助于 了解非诺贝特治疗视网膜炎症和视网膜病变的机制 DR的周细胞丢失。

PROJECT SUMMARY/ABSTRACT Diabetes-induced oxidative stress and chronic inflammation in the retina play a key pathogenic role in diabetic retinopathy (DR). Mitochondrial dysfunction and impairment have been identified as the major cause of oxidative stress and inflammation in DR. Peroxisome Proliferator-Activated Receptor α (PPARα) is a hormone- activated receptor and transcription factor. It is known to regulate lipid metabolism, and thus, PPARα agonists are used clinically to treat hyperlipidemia. Recently, two independent, prospective clinical studies reported a surprising finding that oral administration of fenofibrate, a PPARα agonist, has robust therapeutic effects on DR in type 2 diabetic patients. In the prior grant period, we have successfully demonstrated that the therapeutic effect of fenofibrate on DR is through a PPARα-dependent mechanism. We have shown that PPARα is down- regulated in the retinas of diabetic humans and diabetic animal models, and PPARα has protective effects against DR. We have shown that PPARα knockout (KO) exacerbated, while activation of PPARα by fenofibrate alleviated retinal oxidative stress and retinal inflammation in DR models. This proposal will extend these studies and elucidate the mechanism responsible for the protective effects of PPARα. Our preliminary studies showed that fenofibrate treatment decreased diabetes-induced acellular capillary formation and pericyte loss in the retina. Further, Seahorse analysis showed that PPARα KO resulted in mitochondrial dysfunction in the retina and primary pericytes. Further, PPARα-/- retina showed decreased mitochondrial DNA (mtDNA) copy numbers, suggesting impaired mitochondrial biogenesis and/or DNA repair. This project will address a novel hypothesis that diabetes-induced down-regulation of PPARα expression is responsible for, at least in part, for diabetes-induced mitochondrial dysfunction, which leads to retinal oxidative stress and inflammation in DR. We will determine if PPARα KO exacerbates, while PPARα over-expression alleviates, mitochondrial dysfunction (basal OCR, maximal OCR and ATP production) and mtDNA damage as well as retinal oxidative stress, leukostasis, vascular leakage, acellular capillary formation and pericyte dropout in the retina of diabetic mice. We will also determine the impacts of PPARα deficiency in pericytes on diabetes-induced mitochondrial damage, oxidative stress and pericyte apoptosis using pericyte-specific conditional PPARα KO mice and primary PPARα-/- pericytes. We will also investigate if PPARα regulates mitochondrial biogenesis and function through the SIRT1/PGC-1α pathway using pericyte-specific SIRT1 KO mice and primary SIRT1-/- pericytes. These studies will elucidate a novel pathogenic mechanism responsible for mitochondrial damage and oxidative stress in DR and reveal a new therapeutic strategy for DR. These studies will also contribute to the understanding of the mechanism underlying therapeutic effects of fenofibrate on retinal inflammation and pericyte loss in DR.