Effects Of Interleukin-22 On The Expression Of CCL27 In Human Keratinocytes

Psoriasis is one of the most chronic diseases in dermatology,accounting for 2-3% of the population of the world.The pathogenesis of psoriasis is unclear and it is idifficult to cure at present.So it brings a heavy economic and spiritual burden to patients.Current studies suggest that the pathogenesis of psoriasis is a immune response which is mainly mediated by T-cell on its target——KC.Studies have found that there are a lot of abnormal expressions of chemokines and their receptors systems in psoriasis patients.With the combination of chemokines into their receptors,it attracts leukocytes into the skin and participate in the development of psoriasis.IL-22 is a major cytokine of Th22 cells.The expression of IL-22 in peripheral blood and skin lesions of psoriasis patients is positively correlated with the condition of patients with psoriasis.Our previous studies showed that IL-22 can promote the proliferation of HaCaT cells and inhibit the apoptosis and differentiation of HaCaT cells.In addition,IL-22 can induce the expression of heparin-binding epidermal-growth-factor-like growth factor(HB-EGF)and inhibit the expression of tazarotene-induced gene 3 through the signaling pathways of MAPK-ERK1/2 and JAK2/STAT3.All above indicate that IL-22 plays an important role in the pathogenesis of psoriasis.CCL27,which is known as the cutaneous T cell-attracting chemokine(CTACK),is mainly produced by epidermal keratinocytes of the skin and is one of the important factors in the regulation of skin development and differentiation of keratinocytes.The combination of CCL27 and CCR10 attract lymphocytes into the skin,which plays an important role in immune responses mediated by T cells.CCL27 and CCR10 are considered to be the migration and maintenance factors of the skin T cell in healthy skin and psoriasis and maybe the target factors of psoriasis treatment[6].CCL27 and its receptor-CCR10 have many functions such as recruiting T lymphocytes to the skin in normal skin or inflammatory condition.In early inflammation,CCL27 and CCL17 in the superficial dermal endothelial cells can mediate adhesion and transmembrane migration of lymphocyte.The combination of CCL27 with the dermal extracellular matrix,together with other inflammatory factors such as CCL5,CCL20,CXCL9,and CXCL10 can promote T cell to migrate from the perivascular to the subepidermal.Therefore,CCL27 and CCR10 are regarded as chemokines that migrate and maintain T cells in normal skin or psoriasis patients.Studies of cutaneous T-cell lymphomas show that IL-22 levels in serum are related to LDH,sIL-2R and CCL27.Studies have shown that the T-cell-derived TNF-α can form a positive feedback loop on the induction of CCL27,thereby maintaining inflammatory infiltration and chronic rash.IL-1β can induce the expression of CCL27,while IL-17 can inhibit the expression of CCL27 in the KC.These inflammatory factors are all important factors in the pathogenesis of psoriasis,and IL-22 is another important inflammatory factor in the pathogenesis of psoriasis.On the basis of research we did before,we speculate that IL-22 may interfere the expression of CCL27 in the epidermis of patients with psoriasis through MAPK-ERK1/2 and JAK2/STAT3 signaling pathways,thereby stimulating abnormal proliferation,differentiation,and inflammatory infiltration of epidermal keratinocytes.Object: To study the effects of interleukin-22(IL-22)on the expression of cutaneous T cell-attracting chemokine(CTACK/ CCL27)in human keratinocytes.Methods: 1.HaCaT cells were cultured and divided into eight groups:control group treated with PBS,groups treated by different concentrations of IL-22(12.5、25、50、100、200ug/L)alone,groups treated with the combination of 50ug/LIL-22 with the JAK/STAT inhibitor AG490 or the MAPK-ERK1/2 inhibitor PD98059.After 24-hour culture,total proteins and supernatant were extracted from HaCaT cells.Western blot and enzyme-linked immunosorbent assay(ELISA)were performed to determine the protein level of CCL27.2.Selecting 10 histopathologic paraffin block of vulgaris psoriasis patients from surgery in department of Dermatology of Tianjin Medical University General Hospital and 5 normal skin specimens from surgery in department of Cosmetic surgery branch of Tianjin Medical University General Hospital.Immunohistochemistr-y was performed to observe the expression of CCL27 by the way of hypersensitive two-step immunohistochemical detection.Results: 1.Western blot showed that the protein level of CCL27 was 1.16、1.50、1.52、2.02、4.81 in HaCaT cells treated with IL-22 of 12.5μg/L,25μg/L,50μg/L,100μg/L and 200μg/L respectively,which was 1.16、1.50、1.52、2.02、4.81 times the amount of the control group(1.00).(P<0.05).After the addition of signal pathway inhibitor,the protein level of CCL27 in 50ug/L IL-22+AG490 group(1.02)and 50ug/L IL-22+PD98059 group(0.69)was lower than 50ug/L IL-22 group(1.52).ELISA also showed the same trend in the protein level of CCL27 in HaCaT cells treated by IL-22,which was consistent with Western blot results.The difference was significant.2.In lesions of psoriasis patients,CCL27 is expressed in the cytoplasm of keratinocytes in the entire epidermis.However,CCL27 is mainly expressed in the cytoplasm of keratinocytes which are in the basal layer of the epidermis and less expressed above the basal layer from the normal skin.The expression of CCL27 in psoriasis patients was significantly higher than that in the normal skin.This difference is statistically significant.Conclusions:1.The results of the treatment with 12.5ug/L,25ug/L,50ug/L,100ug/L,and 200ug/L IL-22 can dose-dependently promote the production of CCL27 in HaCaT cells.2.The expression of CCL27 after the addition of a signal pathway blocker was decreased.It is indicated that IL-22 promotes the synthesis and secretion of CCL27 through signaling pathways of MAPK-ERK1/2 and JAK2/STAT3.3.Immunohistochemistry showed a high level of CCL27 in lesions of psoriasis patients.The results above may make CCL27 be the possible targets to develop novel therapies for psoriasis.