Purpose

To investigate the expression of pigment epithelium-derived factor (PEDF) in ocular surface in dry eye disease (DED) and its anti-inflammatory roles and mechanisms, clinically and by experiments in vivo and in vitro.

Methods

A cross-sectional study was conducted to detect the expression of PEDF in tears of dry eye patients by enzyme-linked immunosorbent assay (ELISA). Using dry eye mouse model and human corneal epithelial cells (hCECs) stimulated by hyperosmolarity or inflammatory cytokines, expression of PEDF in corneal epithelial cells, stroma and conjunctiva was quantified by real-time polymerase chain reaction, ELISA and Western blot. Next, either dry eye mice or hyperosmotic hCECs were treated with recombinant PEDF or neutralizing antibodies, and the expressions of inflammatory cytokines and immune cells were detected. Finally, Western blot was performed on MAPK and NF-κB to investigate the signaling pathways by which PEDF played its roles.

Results

Concentrations of PEDF were increased in tears of dry eye patients. Increased PEDF was observed in corneal epithelial cells (CECs) rather than corneal stroma or conjunctiva in dry eye mice. Furthermore, hCECs exposed to hyperosmolarity showed upregulation of PEDF. In vivo and in vitro studies showed that PEDF suppressed the expression of inflammatory cytokines including IL-1β, IL-6, TNF-α and IL-17A, as well as the percentage of Th17 cells in DED. Further investigation showed that PEDF inhibited the phosphorylation of MAPK p38 and JNK in hyperosmotic hCECs.

Conclusions

CECs derived PEDF is increased in DED. PEDF plays anti-inflammatory and immunoregulatory roles in the pathogenesis of DED.

中文翻译：

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色素上皮衍生因子 (PEDF) 在干眼症的发病机制中发挥抗炎作用

目的

通过体内外实验研究干眼病（DED）眼表色素上皮衍生因子（PEDF）的表达及其抗炎作用和机制。

方法

横断面研究采用酶联免疫吸附试验（ELISA）检测干眼患者泪液中PEDF的表达。使用干眼小鼠模型和由高渗性或炎性细胞因子刺激的人角膜上皮细胞 (hCEC)，通过实时聚合酶链反应、ELISA 和蛋白质印迹定量 PEDF 在角膜上皮细胞、基质和结膜中的表达。接下来，用重组PEDF或中和抗体处理干眼小鼠或高渗hCEC，并检测炎性细胞因子和免疫细胞的表达。最后，对 MAPK 和 NF-κB 进行蛋白质印迹以研究 PEDF 发挥作用的信号通路。

结果

干眼症患者泪液中PEDF的浓度增加。在干眼小鼠的角膜上皮细胞 (CEC) 而非角膜基质或结膜中观察到 PEDF 增加。此外，暴露于高渗透压的 hCEC 显示出 PEDF 的上调。体内和体外研究表明，PEDF 抑制了包括 IL-1β、IL-6、TNF-α 和 IL-17A 在内的炎性细胞因子的表达，以及 DED 中 Th17 细胞的百分比。进一步研究表明，PEDF 抑制高渗 hCEC 中 MAPK p38 和 JNK 的磷酸化。

结论

CEC 衍生的 PEDF 在 DED 中增加。PEDF 在 DED 的发病机制中起抗炎和免疫调节作用。