IL-1[beta] Induces IL-6 production in retinal Müller cells predominantly through the activation of P38 MAPK/NF-[kappa]B signaling pathway

• Published in: Experimental cell research 2015-02, Vol.331 (1), p.223
• Main Authors: Liu, Xiufen, Ye, Fei, Xiong, Huabao, Hu, Dan-Ning, Limb, G. Astrid, Xie, Tian, Peng, Liang, Zhang, Pili, Wei, Yi, Zhang, Wiley, Wang, Juan, Wu, Hongwei, Lee, Peng, Song, E, Zhang, David Y
• Format: Article
• Language: English
• Subjects: Cell culture; Cellular biology; Diabetic retinopathy; Phosphorylation; Retina; Signal transduction
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1016/j.yexcr.2014.08.040

IL-6 plays an important role in various inflammatory ocular diseases, including diabetic retinopathy. Müller cells are the major source of inflammatory mediators, including IL-6, in the retina. However, the mechanism of regulating IL-6 production in these cells remains unclear. Examination of signaling pathways in human retinal Müller cells (MIO-M1 cell line) cultured with IL-1[beta], TNF-α, IL-6, IL-8, VEGF, IFN-[GREEK SMALL LETTER GAMMA], glucose or mannitol showed that IL-1[beta] was the most potent stimulator of IL-6 production. In addition, IL-1 [beta] also increased NF-[kappa]B p50 protein level and phosphorylation of p38 MAPK, ERK1/2 and c-Jun. Induction of IL-6 production by IL-1[beta] was significantly reduced by addition of p38 MAPK (SB203580), MEK1/2 (U0126) or NF-[kappa]B (BAY11-7082) inhibitors, with the highest effect being observed with SB203580. To explore the specific elements in IL-6 promoter responsible for IL-1[beta]-induction of IL-6 expression, a series of plasmids bearing various IL-6 promoter mutations were transiently expressed in MIO-MI cells cultured in the presence or absence of IL-1[beta] (10ng/ml) and/or SB203580 (10µM). Results showed that IL-6 promoter activity of the parent pIL-6-Luc651 was significantly enhanced by IL-1[beta], but the level was significantly attenuated by SB203580. Furthermore, the IL-6 promoter activity was also reduced upon deletion of NF-[kappa]B, AP-1 or C/EBP binding sites, with NF-[kappa]B deletion being the greatest. These results are the first demonstration that IL-1[beta] induces IL-6 production in Müller cells by activation of IL-6 promoter activity predominantly through the p38 MAPK/NF-[kappa]B pathway. * IL-1[beta] is a strong IL-6 inducer in human retinal Müller cells (MIO-M1 cell line). * IL-1[beta] induced IL-6 expression was significantly reduced by p38 MAPK inhibition. * Luciferase activity was reduced by IL-6 promoter without NF-[kappa]B binding site. * IL-1[beta]-induced IL-6 production predominantly through the p38 MAPK/NF-[kappa]B pathway.