P218 : The effects of (-)-epigallocatechin-3-gallate on the production of cytokines and cell viability in keratinocytes irradiated with ultraviolet B = P218 : The effects of (-)-epigallocatechin-3-gallate on the production of cytokines and cell viability in keratinocytes irradiated with ultraviolet B

다국어 초록 (Multilingual Abstract)

Background: Ultraviolet rays attacks keratinocytes directly provoking inflammation and cell death. Green tea polyphenols have been known to have photo-protective, antiinflammatory, and anti-oxidant effects. EGCG, the major component in the green tea polyphenol, is known to induce or suppress apoptosis on cells and modulates the secretion of cytokines/chemokines. Objectives: Aim of the study was to investigate the effects of EGCG on UVB-irradiated human keratinocyte HaCaT cells in terms of regulation of proinflammatory cytokines production and cell viability. Methods: The HaCaT cells were cultured and pretreated by EGCG of 5, 50 uM concentration for 6 hours before irradiation of broadband UVB to provoke cell death and cytokine releases. The treated cells were irradiated by 50 mJ/cm2 of UVB and then incubated with EGCG for 24 hours. Cell viability was measured using 3-(4, 5- Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and cytokines were analyzed through enzyme-linked immunosorbent assay (ELISA). Results: UVB irradiation induced marked secretion of IL-6 and TNF-α and secretion of the MCP-1 was moderately increased. Increased levels of IL-6 and MCP-1 after UVB irradiation were markedly suppressed by 50 uM EGCG pretreatment. Secretions of TNF-α was decreased by EGCG pretreatment. EGCG post-treatment after UVB irradiation generally suppressed production of all three tested inflammatory mediators. Comparing with control group, 50 uM EGCG pretreatment inhibited growth of serum starved HaCaT cells independently of UVB irradiation. EGCG showed dual action, i.e. pretreatment before UVB irradiation caused a decrease in cell viability, but post-treatment after UVB irradiation showed photo-protective effects. Conclusion: EGCG modulated the production of cytokines/chemokines and cell viability by the order of EGCG treatment sequence (before/after UVB irradiation), concentration, and kinds of proinflammatory cytokines.