A new pathogenic mechanism for diabetic retinopathy

项目总结/摘要 糖尿病引起的视网膜氧化应激和慢性炎症在糖尿病视网膜病变中起着重要的致病作用 视网膜病变（DR）。线粒体功能障碍和损伤已被确定为 过氧化物酶体激活受体α（过氧化物酶体激活受体α）是一种激素， 激活受体和转录因子。已知其可调节脂质代谢，因此， 临床上用于治疗高脂血症。最近，两项独立的前瞻性临床研究报告称， 令人惊讶的发现是，口服给予非诺贝特（一种PPARα激动剂）对DR具有稳健的治疗效果， 在2型糖尿病患者中。在前一个赠款期间，我们已经成功地证明， 非诺贝特对DR的作用是通过依赖于PPARα的机制实现的。我们已经证明，PPARα是下降的- 在糖尿病人类和糖尿病动物模型的视网膜中调节，并且PPARα具有保护作用 我们已经证明，当非诺贝特激活PPARα时， 减轻DR模型中的视网膜氧化应激和视网膜炎症。这项提案将扩大这些 研究并阐明了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非细胞毛细血管形成和周细胞损失， 视网膜此外，Seahorse分析表明，PPARα KO导致线粒体功能障碍， 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，表明受损的线粒体生物合成和/或DNA修复。这个项目将解决一个小说 假设糖尿病诱导的PPARα表达下调至少部分地导致了 糖尿病诱导的线粒体功能障碍，导致视网膜氧化应激和DR炎症。 将确定当PPARα过度表达加重线粒体功能障碍时， （基础OCR，最大OCR和ATP产生）和mtDNA损伤以及视网膜氧化应激， 糖尿病小鼠视网膜中的白细胞停滞、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的PPARα缺乏对糖尿病诱导的线粒体损伤的影响。 损伤、氧化应激和周细胞凋亡，使用周细胞特异性条件性PPARα KO小鼠， 原代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 使用周细胞特异性SIRT 1 KO小鼠和原代SIRT 1-/-周细胞通过SIRT 1/PGC-1α途径。 这些研究将阐明一种新的致病机制，负责线粒体损伤， 氧化应激在DR中的作用，并揭示了DR的新治疗策略。这些研究也将有助于 了解非诺贝特对视网膜炎症的治疗作用机制， DR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.