ATF4双向调控NLRP3炎症小体和p62-线粒体自噬在糖尿病视网膜炎症反应中的作用及机制

Diabetic retinopathy (DR) is the leading cause of blindness. Our previous studies have demonstrated that activating transcription factor 4 (ATF4) induces the inflammatory response in DR, but the mechanism is poorly understood. ATF4 can promote the activity of NADPH oxidases (NOX) to produce the reactive oxygen species (ROS), which is the critical signal for activating NLRP3 inflammasome. Our preliminary data suggested silenced ATF4 can prevent the activation of NLRP3 inflammasome induced by high glucose, which indicates that ATF4 contributes to retinal inflammation by activation of NLRP3 inflammasome. DR involves a chronic low-grade retinal inflammation, assuming a negative feedback loop to restrict excessive inflammation. The recent study has discovered that p62 restrains NLRP3 inflammasome activation by promoting mitochondrial autophagy. And there is ATF4 binding site in the promoter region of p62. Additionally, our preliminary studies indicated that ATF4 can upregulate the expression of p62. Thus, we hypothesize that ATF4 restrains excessive NLRP3 inflammasome activation by promoting p62-dependent mitophagy. This project intends to investigate whether ATF4 mediates the activation of NLRP3 inflammasome through the NOX pathway, and what is the role of ATF4 in p62 expression and subsequent mitophagy in the process of DR. This project will provide the experimental basis for the bidirectional role of ATF4 on NLRP3 inflammasome, which plays critical role in the persistent and low-grade inflammation in DR. We anticipate that completion of the proposed studies will provide mechanistic insights into ATF4 signaling pathways in retinal inflammation and identify new therapeutic targets for the prevention and treatment of DR.

糖尿病视网膜病变（DR）是致盲性眼病，我们前期研究发现活化转录因子ATF4参与诱导DR炎症反应，但机制未明。ATF4能增强还原型辅酶Ⅱ氧化酶（NOX）活性促进活性氧生成，而活性氧是NLRP3炎症小体激活的关键信号。预实验显示沉默ATF4可阻断高糖激活NLRP3炎症小体的作用，提示ATF4可能通过激活NLRP3炎症小体诱导DR炎症反应。DR炎症反应具有持续慢性低度的特点，理应存在负反馈调控机制。最新研究报道p62能促进线粒体自噬、灭活NLRP3炎症小体，p62启动子区有ATF4结合位点；预实验显示过表达ATF4上调p62，推测ATF4可能通过调控p62表达抑制炎症小体过度激活。本项目拟探讨DR病程中ATF4通过NOX途径激活NLRP3炎症小体的作用，以及ATF4促进p62表达诱导线粒体自噬；从而阐明ATF4双向调控机制在DR慢性低度炎症反应的关键作用，为DR防治提供新的靶点和依据。

糖尿病视网膜病变（DR）已成为全球性的工作年龄段成年人致盲的首要因素。但是DR的致病分子机制仍是有很多未知，并且已有的治疗方案疗效差、费用高。因此需要更加全面的了解DR的发病机制，并寻找可能的更优的治疗靶点。我们的研究证实NLRP3炎症小体在DR微血管病变的起着促进炎症反应的作用，且二甲双胍能通过抑制NLRP3炎症小体的激活从而改善糖尿病诱导的动脉粥样硬化。上述结果表明NLRP3炎症小体是治疗糖尿病并发症的关键靶点。我们进一步揭示了激活NLRP3炎症小体的2个关键分子：ATF4和NOX4。我们证明NOX4能通过ROS来激活视网膜内皮细胞NLRP3炎症小体。上述结果已经发表。我们尚在进行的研究结果则表明ATF4很可能是作为转录因子来调控视网膜内皮细胞NLRP3的表达和活化。因此，我们的成果揭示了DR状态下，ATF4、NOX4和NLRP3炎症小体在视网膜微血管病变的炎症及渗漏的作用和分子机制，更加全面地展示了DR微血管病变过程中的病理变化，并为上述分子成为DR的生物标记分子或者治疗靶点提供了理论依据。.此外，我们的建立了含有12906例2型糖尿病患者信息的大队列，并证实了4个促进DR发病或者疾病进展的高风险因素：超过60岁、患有2型糖尿病时间长度超过10年、来自于中等收入地区、女性和升高的单核细胞/高密度脂蛋白胆固醇比例。我们还证明了血糖波动会引起2型糖尿病患者的冠状动脉粥样硬化和心脏结构及功能，并且提出了优化的“基础胰岛素+口服降糖药”治疗方案来更好地控制血糖波动。