Epigallocatechin gallate inhibits the proliferation and apoptosis of keratinocytes induced by interleukin-17 / 中华皮肤科杂志

ABSTRACT

Objective To evaluate the protective effect of epigallocatechin gallate (EGCG) against interleukin (IL)-17-induced injury to keratinocytes,and to explore its mechanism.Methods Some cultured HaCaT cells were divided into 3 groups to be treated with IL-17 alone at concentrations of 50,70,90 μg/L,respectively,with those receiving no treatment as the blank control group.Some HaCaT cells were divided into 5 groups:IL-17 group treated with 90 μg/L IL-17 alone,IL-17 + EGCG group treated with 90 μg/L IL-17 and 60 μmol/L EGCG,IL-17 + SP600125 group treated with 90 μg/L IL-17 and SP600125 (a JAK signaling pathway inhibitor),IL-17+ EGCG + anisomycin group treated with 90μg/L IL-17,60xmol/L EGCG and anisomycin (a Janus kinase signaling pathway activator),and blank control group receiving no treatment.After different durations of treatment,CCK-8 assay was performed to evaluate cellular proliferative activity,flow cytometry to detect cell apoptosis,enzyme-linked immunosorbent assay (ELISA) to measure expression levels of IL-6,IL-23 and IL-8,and Western-blot analysis to determine protein expressions of c-Jun N-terminal kinase (JNK) and phosphorylated JNK (P-JNK).Results IL-17 promoted cellular proliferation of HaCaT cells,and the proliferation rate,which was correlated with the concentration of IL-17,reached the maximum in the 90-μg/L IL-17 group (P ＜ 0.05).EGCG at 60 μmol/L significantly inhibited cellular proliferation of,promoted apoptosis in,and reduced IL-6,IL-23 and IL-8 expressions in,HaCaT cells induced by 90 μg/L IL-17 (all P ＜ 0.05).Compared with the IL-17 group,the IL-17 + EGCG group and IL-17 + SP600125 group both showed significantly decreased P-JNK expression,cell proliferation rate and IL-6,IL-23 and IL-8 expression levels (all P ＜ 0.05).However,compared with the IL-17 + EGCG group,the IL-17 + EGCG + anisomycin group showed significantly increased protein expression of P-JNK,cell proliferation rate and IL-6,IL-23 and IL-8 expression levels (all P ＜ 0.05).Conclusion EGCG protected against IL-17-induced injury to HaCaT cells,such as abnormal cell proliferation,apoptosis and inflammatory response,likely by inhibiting the JNK signaling pathway.