Resveratrol Inhibits Secretion of Interleukin 8 by Regulation of Autophagic Flux in Ultraviolet B-stimulated Keratinocytes

Abstract

Abstract. Objective:. The plant polyphenol resveratrol (3,4′,5-trihydroxystilbene) (RSV) has been proposed for use because of its protective effect on ultraviolet (UV)-induced skin disorders. In UVB-induced skin damage, cell autophagy and apoptosis have been approved to prevent the damage and to contribute to the cytoprotective role of RSV; however, the detailed mechanism remains unknown. So, we conducted this study to investigate the cytoprotective effects of RSV on UVB-irradiated human epidermal keratinocytes (HEKs) and its undergoing mechanisms. Methods:. Secretion of thirty-six inflammatory cytokines of HEKs induced by 50 mJ/cm2 UVB at 0, 12, 24, and 48 hours were detected by a human cytokine assay and the interleukin (IL)-8 protein level in the culture media were determined by ELISA. Next, HEKs were treated with or without 100 μmol/L RSV in the presence or absence of 50 mJ/cm2 UVB, and activator protein 1 and NF-κB-related proteins were measured by Western blot. Furthermore, cells exposed to UVB radiation were treated with apoptosis activators procaspase-activating compound 1 (PAC-1), apoptosis activator 2 (AA2) or RSV to investigate the effect of RSV on the percentage of apoptotic cells by flow cytometry. Then cells were treated with autophagy inhibitors LY294002, 3-methyladenine (3-MA) or RSV in the presence of UVB and chloroquine (CQ) to investigate the effect of RSV on autophagy through detecting microtubule-associated protein 1 light chain 3 (LC3) expression by western blot. Finally, the effect of LY294002, 3-MA, ATG5 siRNA, PAC-1, and AA2 on RSV-mediated reduction of IL-8 expression was determined by ELISA assay. Results:. RSV treatment decreased the secretion of IL-8 (UVB vs. UVB + RSV: [1454.05 pg/mL ± 52.95 pg/mL] vs. [553.68 pg/mL ± 206.03 pg/mL], P 0.05), whereas neither PAC-1 nor AA2 exerted similar effects. Conclusion:. RSV may regulate autophagic flux to inhibit IL-8 expression in UVB-challenged keratinocytes.