Effects of interleukin-22 on the expression of CC chemokine ligand 27 in human epidermal keratinocytes

Objective To evaluate the effects of interleukin-22 (IL-22) on the expression of CC chemokine ligand 27 (CCL27) in human epidermal keratinocytes, and to explore its mechanism. Methods Immunohistochemical study was performed to determine the expression of CCL27 in skin lesions of 10 patients with psoriasis and skin tissues of 5 healthy controls. Cultured HaCaT cells were divided into 8 groups: control group treated with PBS, 5 IL-22 groups treated with 12.5, 25, 50, 100 and 200 μg/L IL-22 respectively, 2 signaling pathway inhibition groups treated with 50 μmol/L AG490 (JAK2/STAT3 signaling pathway inhibitor) or PD98059 (MAPK-ERK1/2 signaling pathway inhibitor) for 2 hours followed by the treatment with 50 μg/L IL-22 in the 5% CO2 incubator at 37 ℃. After 24-hour cultivation, total proteins were extracted, and culture supernatants were collected, and both Western blot analysis and enzyme-linked immunosorbent assay (ELISA) were performed to determine the expression of CCL27. Results Immunohistochemical study showed that the expression of CCL27 was significantly higher in the skin lesions of the patients with psoriasis than in the skin tissues of the healthy controls. Western blot analysis revealed that the protein expression of CCL27 in the 12.5-, 25-, 50-, 100- and 200-μg/L IL-22 groups was 0.491 ± 0.013, 0.620 ± 0.019, 0.623 ± 0.014, 0.802 ± 0.052 and 1.138 ± 0.013 respectively, which were all higher than that in the control group (0.413 ± 0.013, all P < 0.01) . The expression of CCL27 was significantly lower in the IL-22 + AG490 group (0.411 ± 0.019) and IL-22 + PD98059 group (0.280 ± 0.012) than in the 50-μg/L IL-22 group (both P < 0.01) . ELISA also showed the same trend of changes in the level of CCL27 in the above groups as Western blot showed. Conclusion IL-22 can promote the expression of CCL27 in HaCaT cells, which may be associated with the MAPK-ERK1/2 and JAK2/STAT3 signaling pathways. Key words: Psoriasis; Interleukins; Keratinocytes; Chemokine CCL27; Janus kinase 2; Mitogen-activated protein kinases; Interleukin-22