Lee I-Ta, Liu Shiau-Wen, Chi Pei-Ling, Lin Chih-Chung, Hsiao Li-Der, Yang Chuen-Mao
Department of Physiology and Pharmacology and Health Ageing Research Center, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan.
Department of Anesthetics, Chang Gung Memorial Hospital at Lin-Kou and College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan.
PLoS One. 2015 Feb 12;10(2):e0117911. doi: 10.1371/journal.pone.0117911. eCollection 2015.
Retinal inflammatory diseases induced by cytokines, such as tumor necrosis factor-α (TNF-α) are associated with an up-regulation of intercellular adhesion molecule-1 (ICAM-1) in the retinal pigment epithelial cells (RPECs). Retinal pigment epithelium (RPE) is a monolayer of epithelial cells that forms the outer blood-retinal barrier in the posterior segment of the eye, and is also implicated in the pathology of, such as neovascularization in age-related macular degeneration (AMD). However, the detailed mechanisms of TNF-α-induced ICAM-1 expression are largely unclear in human RPECs. We demonstrated that in RPECs, TNF-α could induce ICAM-1 protein and mRNA expression and promoter activity, and monocyte adhesion. TNF-α-mediated responses were attenuated by pretreatment with the inhibitor of PKCs (Ro318220), PKCδ (Rottlerin), MEK1/2 (U0126), JNK1/2 (SP600125), or AP-1 (Tanshinone IIA) and transfection with siRNA of TNFR1, TRAF2, JNK2, p42, or c-Jun. We showed that TNF-α could stimulate the TNFR1 and TRAF2 complex formation. TNF-α-stimulated JNK1/2 was also reduced by Rottlerin or SP600125. However, Rottlerin had no effect on TNF-α-induced p42/p44 MAPK phosphorylation. We observed that TNF-α induced c-Jun phosphorylation which was inhibited by Rottlerin or SP600125. On the other hand, TNF-α-stimulated ICAM-1 promoter activity was prominently lost in RPECs transfected with the point-mutated AP-1 ICAM-1 promoter plasmid. These results suggest that TNF-α-induced ICAM-1 expression and monocyte adhesion is mediated through a TNFR1/TRAF2/PKCδ/JNK1/2/c-Jun pathway in RPECs. These findings concerning TNF-α-induced ICAM-1 expression in RPECs imply that TNF-α might play an important role in ocular inflammation and diseases.
由细胞因子（如肿瘤坏死因子-α，TNF-α）诱导的视网膜炎症性疾病与视网膜色素上皮细胞（RPECs）中细胞间黏附分子-1（ICAM-1）的上调有关。视网膜色素上皮（RPE）是一层上皮细胞，在眼后段形成外血视网膜屏障，并且也与诸如年龄相关性黄斑变性（AMD）中的新生血管形成等病理过程有关。然而，在人RPECs中，TNF-α诱导ICAM-1表达的详细机制在很大程度上尚不清楚。我们证明，在RPECs中，TNF-α可诱导ICAM-1蛋白、mRNA表达及启动子活性，并诱导单核细胞黏附。用蛋白激酶C（PKC）抑制剂（Ro318220）、PKCδ（罗特列素）、MEK1/2（U0126）、JNK1/2（SP600125）或AP-1（丹参酮IIA）预处理以及用TNFR1、TRAF2、JNK2、p42或c-Jun的小干扰RNA（siRNA）转染可减弱TNF-α介导的反应。我们表明，TNF-α可刺激TNFR1和TRAF2复合物形成。罗特列素或SP600125也可降低TNF-α刺激的JNK1/2。然而，罗特列素对TNF-α诱导的p42/p44丝裂原活化蛋白激酶（MAPK）磷酸化无影响。我们观察到TNF-α诱导c-Jun磷酸化，而罗特列素或SP600125可抑制该磷酸化。另一方面，在用点突变的AP-1 ICAM-1启动子质粒转染的RPECs中，TNF-α刺激的ICAM-1启动子活性显著丧失。这些结果表明，TNF-α诱导的ICAM-1表达及单核细胞黏附是通过RPECs中的TNFR1/TRAF2/PKCδ/JNK1/2/c-Jun途径介导的。这些关于TNF-α诱导RPECs中ICAM-1表达的发现意味着TNF-α可能在眼部炎症和疾病中起重要作用。
