Investigation That Interleukin-22(IL-22) Effects On Proliferation, Apoptosis And Secreting HB-EGF Of HaCaT Cells

Psoriasis is a common skin disease recurrence by immune cell-mediated chronic inflammatory, which the incidence rate is about2%-3%all over the world. The main symptoms exhibt excessive proliferation of the epidermis, parakeratosis and a large number of immune cells that around dermal vascular. Psoriasis is caused by keratinocytes cells and disorders of immune cells. So far, the primarily pathogenesis of psoriasis is the immune response mediated by T cells in KC as a target. Th22cells are newly discovered T cell subsets, which despend on IL-22achieve its function. Investigations have shown that there is a positive relevance in plasma IL-22and severity of psoriasis. Our previous studies have shown that heparin-binding EGF-like growth factor (heparin-binding epidermal-growth-factor-like growth factor, HB-EGF) plays an important role in KC abnormal proliferation of psoriatic epidermis and outcome. Therefore, we hypothesized that Th22cells and IL-22secretion may interfere with KC HB-EGF, and then participate in the abnormal proliferation of psoriatic epidermis occurrence and development. The study is to investigate how IL-22infects HaCaT cell function and HB-EGF expression in HaCaT cells, which is significant to reveal the pathogenesis of skin abnormal proliferation in psoriasis.Objective To investigate that interleukin-22(IL-22) and IL-22siRNA effect on proliferation, apoptosis and salivating HB-EGF of HaCaT cells.Methods After being treated with IL-22in different doses (12.5μg/L,25μg/L,50μg/L,100μg/L、200μg/L) and IL-22siRNA, proliferation of HaCaT cell was determined by MTT. Apoptosis rate was assessed with flow cytometry. Expression of HB-EGF by immunohistochemical method、Western blot、ELISA and real-time quantitative RT-PCR.Results1Proliferation of HaCaT cell treated with IL-22increased significantly, compared with that of the control. Proliferation of HaCaT cell treated with IL-22siRNA decreased significantly, compared with that of the control.2The apoptosis rate of HaCaT cell treated with IL-22was lower than that of the control, but treated with IL-22siRNA was higher than that of the control, and the difference werestatistically significant.3The intensity of HB-EGF expression in HaCaT cell is related with the dose of IL-22:compared with the control, the number of HB-EGF secreting is higher treated by different dose IL-22. The bigger dose IL-22, the more HB-EGF secreting. But the number of HB-EGF secreting is higher treated by IL-22siRNA decreased significantly.Conclusions IL-22can promote HaCaT cell proliferation and inhibit its apoptosis, simultaneously increase the secretion of HB-EGF in HaCaT. IL-22siRNA can inhibit HaCaT cell proliferation and promote apoptosis. IL-22can promote HaCaT cell secrete HB-EGF, IL-22siRNA can inhibit HaCaT cell secreting HB-EGF. HaCaT cell secrete HB-EGF increased maybe the reason that IL-22promote HaCaT cell proliferation and inhibit apoptosis effectively.