促炎因子Nogo-B在糖尿病性视网膜病变中的作用和机制

Diabetic retinopathy (DR) is a microvascular complication of diabetes and a leading cause of vision loss in working-age adults. DR is also known as a chronic inflammatory disorder. During the early stage of DR, proinlfammatory proteins, such as intercellular adhesion molecule-1 (ICAM-1) and tumor necrosis factor-α (TNF-α), are upregulated, and increased leukostasis is observed. These early pathologic changes are associated with upregulation of vascular endothelial growth factor (VEGF). Since VEGF may be required for the maintenance and survival of retinal neurons, revealing cellular mechanism of VEGF actions and looking for novel targets for the safety and effectiveness of DR therapies become necessary. Our previous work has demonstrated that Müller cell-derived VEGF contributes significantly to ischemia-induced retinal neovascularization and diabetes-induced retinal inflammation. .Nogo isoforms which include Nogo-A, B and C, are part of a superfamily of proteins called reticulons. Nogo-A and Nogo-C are highly expressed in the central nervous system, whereas Nogo-B is found in most tissues. Nogo-B is mainly expressed in vascular endothelial cells and cardiac myocytes. Many studies have shown that Nogo-B plays important roles in apoptosis inducing, vascular remodeling, angiogenesis and neovascularization. Recently, Nogo-B is identified as a novel proinflammatory factor and a significant contributor to inflammation. In the animal model of inflammation, endothelial Nogo-B regulates leukocyte transmigration. Nogo-/- mice showed a marked decrease in the expression of inflammatory factors. However, the role of Nogo-B in retinopathy has never been reported at home and abroad. Our preliminary data showed that Nogo-B was expressed in human retinal capillary endothelial cells (HRCECs), and was significantly upregulated under hypoxia and high glucose. Thus we hypothesize that Nogo-B contributes to the initiation and development of DR, which is associated with PI3K-Akt-NF-κB pathway. To confirm our hypotheses, we will generate a mouse model of diabetic retinopathy and use different experimental technology,such as transfection of samll-interfering RNA, RT-PCR, Western blot analysis, immunofluorescent staining and so on, to investigate the expression and localization of Nogo-B in mice retina, the effect and mechanism of Nogo-B on diabetes-induced retinal vascular inflammation. And we will also use the Cre/lox-based conditional VEGF knockout mice and examine the effect of Nogo-B on diabetes-induced retinal inflammation without VEGF, revealing the relationship between Nogo-B and VEGF during development of DR. Our study will further reveal the pathogenesis of DR, and provide new insights and a novel target for prevention and treatment of DR.

糖尿病视网膜病变（DR）是危害中老年患者视力的重要眼病，目前认为炎症反应在DR发病过程中起了重要的作用。我们以往的研究发现Müller细胞来源的VEGF是糖尿病诱导的视网膜炎症反应中的关键因子。Nogo-B是近几年新发现的在炎症反应中起重要作用的促炎因子，但是Nogo-B与视网膜疾病的关系，迄今国内外尚无报道。在前期研究中，我们发现人视网膜血管内皮细胞有Nogo-B表达，且在缺氧和高糖状态下，Nogo-B表达明显升高。我们推测Nogo-B通过炎症反应参与DR的发生发展，且可能与PI3K-Akt-NF-κB信号转导途径有关。为证实该假说，我们将复制小鼠DR模型，采用分子生物学等技术，观察DR小鼠视网膜上Nogo-B的表达和定位，Nogo-B对视网膜血管炎症反应的影响及其信号转导途径，以及Nogo-B与VEGF在DR中的关系。本课题将进一步揭示DR的发病机制，并为DR的防治提供新思路和新靶点。

糖尿病视网膜病变（DR）是危害中老年患者视力的重要眼病，目前认为炎症反应在DR发病过程中起了重要的作用。Nogo-B是近几年新发现的在炎症反应中起重要作用的促炎因子，但是Nogo-B与视网膜疾病的关系，迄今国内外尚无报道。在前期研究中，我们发现人视网膜血管内皮细胞有Nogo-B表达，且在缺氧和高糖状态下，Nogo-B表达明显升高。因此我们通过建立小鼠DR模型，深入探讨炎症反应在Nogo-B与DR发生发展的关系中的作用，及可能的信号转导途径。我们采用分子生物学等技术，观察DR小鼠视网膜上Nogo-B的表达和定位，通过转染针对Nogo-B的siRNA，沉默小鼠视网膜上Nogo-B的表达，从而观察Nogo-B对视网膜血管炎症反应的影响及其信号转导途径。实验结果显示，Nogo-B在小鼠视网膜上各层组织中均有表达，其中以神经节细胞层、内丛状层和内核层上表达最为显著。在糖尿病状态下，小鼠视网膜上Nogo-B的表达明显上调。同时在糖尿病状态下，沉默视网膜上Nogo-B的表达，可以抑制糖尿病诱导的TNF-α，ICAM-1和p-p65表达的上调，使视网膜血管壁上粘附的白细胞数减少，并改善视网膜血管内白蛋白的渗漏。我们的结果提示Nogo-B通过参与炎症反应，在糖尿病视网膜病变的发病过程中起了重要作用。因此本课题在一定程度上，进一步揭示了DR的发病机制，并为DR的防治提供了新思路和新靶点。