Molecular Mechanisms of Severe Diabetic Retinopathy

摘要： 糖尿病患者视力丧失的主要原因包括糖尿病黄斑水肿和严重糖尿病 视网膜病变(包括严重的非增殖性糖尿病视网膜病变和增殖性糖尿病视网膜病变) 这与视网膜内皮细胞的广泛损伤有关；然而，其分子机制 糖尿病对血管内皮细胞的进行性损害背后的原因还知之甚少。此外，尽管 可预防的措施，严重的糖尿病视网膜病变最终仍会在大量糖尿病患者中发生 导致失明。因此，寻找新的分子靶点来防止糖尿病视网膜病变的进展 是一种未得到满足的需求。在这个项目中，我们建议测试NADPH氧化酶4(NOX4)在视网膜内皮细胞中的作用 细胞作为防治重症糖尿病视网膜病变的新分子靶点。在最近的研究中， 我们已经证明，NOX4是视网膜内皮细胞中NADPH氧化酶的主要亚型，并且NOX4的表达 在糖尿病视网膜病变动物模型中，在视网膜血管中表达上调。NOX4基因的遗传消融 血管内皮细胞减少糖尿病小鼠视网膜血管通透性并减轻异常新生血管 氧诱导的视网膜病变中的生长。相反，在内皮细胞中过表达NOX4足以 导致视网膜血管渗漏和变性。此外，最近的一项全基因组关联研究(GWAS) 确定NOX4是严重糖尿病视网膜病变的潜在危险基因。总体而言，这些试验性和 临床结果提示NOX4在糖尿病介导的内皮细胞损伤和视网膜中起重要作用 血管病变。然而，NOX4诱导内皮细胞损伤的机制及其与人类的关系 疾病仍然是一个研究不足的领域。在这个项目中，我们将首先研究NOX4在人视网膜中的表达 糖尿病视网膜病变的不同阶段。使用可诱导的内皮细胞特异性条件性基因敲除 小鼠品系，我们将在糖尿病发病后的不同时间点删除NOX4，以建立内皮细胞的作用 NOX4在糖尿病视网膜病变发生发展中的作用我们将研究NOX4的机制- NOX4介导的内皮细胞死亡和衰老及其激活的新信号通路 血管内皮细胞表达上调。最后，我们将测试专门针对NOX4的新型药物抑制剂 对糖尿病视网膜病变的预防和治疗作用。我们预计，在成功完成 提出的研究不仅将提供糖尿病视网膜病变的机制洞察，而且还将开发新的 针对人类基因研究确定的危险基因的治疗，用于预防严重的糖尿病视网膜病变。

Abstract: Major causes of vision loss in people with diabetes include diabetic macular edema and severe diabetic retinopathy (including severe non-proliferative diabetic retinopathy and proliferative diabetic retinopathy), both of which are associated with extensive injury of retinal endothelial cells; however, the molecular mechanisms underlying the progressive damage to endothelial cells in diabetes are poorly understood. Further, despite preventable measures, severe diabetic retinopathy still occurs in a large number of diabetic individuals eventually leading to blindness. Thus, identifying novel molecular targets to prevent the progression of diabetic retinopathy is an unmet need. In this project, we propose to test the role of NADPH oxidase 4 (Nox4) in retinal endothelial cells as a novel molecular target for the prevention and treatment of severe diabetic retinopathy. In recent studies, we have shown that Nox4 is a major isoform of NADPH oxidases in retinal endothelial cells and Nox4 expression is upregulated in retinal blood vessels in animal models of diabetic retinopathy. Genetic ablation of Nox4 gene in endothelial cells reduces retinal vascular permeability in diabetic mice and alleviates aberrant new vessel growth in oxygen-induced retinopathy. In contrast, overexpression of Nox4 in endothelial cells is sufficient to induce retinal vascular leakage and degeneration. Furthermore, a recent genome-wide association study (GWAS) identified Nox4 as a potential risk gene for severe diabetic retinopathy. Collectively, these experimental and clinical findings suggest an important role of Nox4 in diabetes-mediated endothelial cell injury and retinal vasculopathy. However, the mechanisms by which Nox4 induces endothelial injury and its relevance to human disease remain an understudied area. In this project, we will first characterize Nox4 expression in human retinas with different stages of diabetic retinopathy. Using an inducible endothelial cell specific conditional knockout mouse line, we will delete Nox4 at various time points after diabetes onset to establish the role of endothelial Nox4 in the development and progression of diabetic retinopathy. We will investigate the mechanisms of Nox4- mediated endothelial death and senescence and elucidate novel signaling pathways activated by Nox4 upregulation in endothelial cells. Finally, we will test novel pharmacological inhibitor that specifically targets Nox4 for its preventive and therapeutic effects on diabetic retinopathy. We anticipate that the successful completion of the proposed studies will not only provide mechanistic insight of diabetic retinopathy but also develop new treatment that targets a risk gene identified by human genetic study for prevention of severe diabetic retinopathy.