Nrf2-PGDS正反馈环路在高度近视视网膜萎缩中的作用及机制研究

The pathogenesis of progressive retinal atrophy in high myopia（HM）is still unclear. The levels of prostaglandin -D2 synthase (PGDS)and transferrin (Tf) were found to be decreased in vitreous samples from HM patients by using label-free quantitative proteomics analysis. It is reported that the positive feedback loop of Nrf-2 and PGDS is a major defense mechanism against oxidative damage. Tf, the main iron transporter, is a natural iron chelator essential for iron homeostasis and its down-regulation results in iron overload-mediated oxidative injury.After constructed to PGDS-overexpression and PGDS-knockout status, human retinal pigment epithelium (rRPE) lines and form-deprivation myopia animal models were exposed to iron-induced oxidative damage to investigate the molecular mechanism of Nrf2-PGDS loop in HM and its relationship with iron balance. Specific repressors of MARCKS、PGD2-DP-pERK1and PDJ2-PPARγ pathways were used to find out the specific pathway of Nrf2-PGDS involved in HM，so did co-immunoprecipitation and DNA assay hybridization techniques. The possibility of intravitreal synthetic PGDS injection to treat HM-related retinopathy was evaluated.

高度近视视网膜萎缩的分子发病机制尚不清楚。我们收集三类疾病高度近视及非高度近视患者玻璃体行Label-free蛋白非标定量分析，结果示三组高度近视均出现前列腺素D2合成酶(Prostaglandin -D2 Synthase, PGDS)及转铁蛋白（Transferrin，Tf）表达下调。PGDS与核转录因子2（Nrf2）的正反馈环路，是机体抗氧化应激损伤最重要的防御屏障。Tf影响体内铁代谢平衡，而铁的代谢失衡可造成氧化应激损伤。本课题以人视网膜色素上皮细胞、铁氧化应激损伤联合形觉剥夺近视动物模型为研究对象，造PGDS过表达及基因敲除无表达，加入信号通路阻断剂（MARCKS、PGD2-DP-pERK1及PDJ2-PPARγ），利用免疫共沉淀、基因微阵列杂交等技术，深入研究Nrf2-PGDS在眼内作用机制及其与铁代谢平衡相互关系，并探讨眼内注射PGDS能否作为治疗高度近视视网膜病变的可能性。

本项研究旨在探讨Nrf2-PGDS在高度近视眼内的调控作用及其与铁代谢平衡相互关系，为了解高度近视发病机制提供新思路。本研究内容包含以下内容：1): 探讨人高度近视患者眼内Nrf-2、PGDS及铁含量动态表达情况；2):造PDGS过表达及欠表达模型，比较各组间Nrf2-PGDS动态变化与屈光状态、眼轴长度变化、眼内氧化应激状态、视网膜形态变化的相互关系；3）：体外培养人视网膜色素上皮细胞（ARPE19），造PGDS过表达及PGDS基因沉默稳定细胞系，予氧化应激（H2O2及FeSO4），观察Nrf2、PGDS及其下游产物动态表达情况。迄今我们通过对高度近视及非高度近视患者玻璃体行Label-free蛋白非标定量分析，结果显示病例组出现前列腺素D2合成酶(Prostaglandin -D2 Synthase, PGDS)及转铁蛋白（Transferrin，Tf）表达下调。体外ARPE19细胞实验证实PGDS具有明确的抗氧化应激作用（实验还在进行二次验证）。