Department of Ophthalmology, Tianjin Orbit Research Institute, the Second Hospital of Tianjin Medical University, Tianjin, China.
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
Sci Rep. 2017 Sep 5;7(1):10421. doi: 10.1038/s41598-017-09636-w.
This study was to explore the mechanism by which reactive oxygen species (ROS)-induced oxidative stress involved in the pathogenesis of fungal keratitis using an in vivo experimental keratitis mouse model and an in vitro culture model of human corneal epithelial cells (HCECs). Compared to normal control mice and HCECs, ROS production was markedly increased in fungal corneas and HCECs exposed to Candida albicans, accompanied by p38 mitogen-activated protein kinases (MAPK) activation. Increased products of oxidative markers, malondialdehyde (MDA), 4-hydroxynonenal (HNE), mitochondria DNA 8-OHdG and aconitase-2 were observed in fungal infected corneas and HCECs. Fungal infection also increased the mRNA expression and protein production of heme oxygenase-1 (HMOX1) and cyclooxygenase-2 (COX2), with suppressed levels of antioxidant enzymes, superoxide dismutase-1 (SOD1), glutathione peroxidase-1 (GPx1) and peroxiredoxin-4 (PRDX4). Interestingly, the levels of ROS, oxidative markers and oxygenases were significantly reduced by co-cultured p38 inhibitor SB203580. Furthermore, SB203580 restored the levels of antioxidant enzymes suppressed by fungus. Our findings demonstrated for the first time that ROS-induced oxidative injury is involved in pathogenesis of fungal keratitis via p38 MAPK pathway, suggesting the novel therapeutic targets for the potential treatment of fungal keratitis.
本研究通过体内实验性角膜炎小鼠模型和体外培养的人角膜上皮细胞（HCEC）模型，探讨活性氧（ROS）诱导的氧化应激在真菌性角膜炎发病机制中的作用机制。与正常对照组小鼠和 HCEC 相比，白色念珠菌感染的真菌角膜和 HCEC 中 ROS 生成明显增加，同时伴有 p38 丝裂原活化蛋白激酶（MAPK）激活。在真菌感染的角膜和 HCEC 中观察到氧化标志物丙二醛（MDA）、4-羟基壬烯醛（HNE）、线粒体 DNA 8-OHdG 和 aconitase-2 的产物增加。真菌感染还增加了血红素加氧酶-1（HMOX1）和环氧化酶-2（COX2）的 mRNA 表达和蛋白产生，同时抗氧化酶超氧化物歧化酶-1（SOD1）、谷胱甘肽过氧化物酶-1（GPx1）和过氧化物酶 4（PRDX4）的水平受到抑制。有趣的是，共培养 p38 抑制剂 SB203580 可显著降低 ROS、氧化标志物和加氧酶的水平。此外，SB203580 恢复了真菌抑制的抗氧化酶水平。我们的研究结果首次表明，ROS 诱导的氧化损伤通过 p38 MAPK 途径参与真菌性角膜炎的发病机制，提示了治疗真菌性角膜炎的潜在新治疗靶点。
