The Role And Mechanism Of Prolactin And CCL20 In The Pathogenesis Of Psoriasis

Research backgroundThe physiological function of skin is regulated by many factors,among which the regulation of neuroendocrine hormones is one of the important factors.Prolactin(PRL)is a polypeptide hormone secreted by anterior pituitary gland,which regulates the growth and development of mammary gland and promotes lactation.PRL is not only an endocrine hormone,but also a cytokine,belonging to the family of prolactin/growth hormone/placental prolactin hormones.Prolactin receptor(PRLR)widely exists in various tissues of the body,and many pituitary tissues including immune cells,hair follicles,sebaceous glands,skin keratinocytes also synthesize prolactin.Therefore,the role of extramammary prolactin has been paid more and more attention[34].Psoriasis is a common autoimmune inflammatory skin disease.Some clinical studies and observations have found that elevated PRL levels can aggravate the development of psoriasis,but the mechanism of prolactin involved in the onset and development of psoriasis remains unclear.Kanda,N.et al.found that prolactin acts on human keratinocytes and increases the production of chemokines CXCL9,CXCL10 and CXCL11 by keratinocytes.These chemokines can attract Thl cells.These results suggest that prolactin can induce the infiltration of Thl cells in psoriatic lesions[35].Compared with Thl cells,Th17 cells and related cytokines such as IL-22 play a more important role in the pathogenesis of psoriasis.Chemokine receptor CCR6 is the marker of Th17 cells.Chemokine CCL20 is the only ligand of CCR6.CCL20 recruits Th17 cells.Whether PRL can promote the secretion of CCL20 by keratinocytes and induce the infiltration of Th17 cells into psoriatic lesions is worth exploring.Objective1.To observe the effect of prolactin(PRL)on the proliferation of human immortalized keratinocytes(HaCaT cells)and the expression of CCL20 induced by IL-22.2.To observe and analyze the serum level of CCL20 in patients with psoriasis and its correlation with the severity of psoriasis.3.Observation of serum prolactin level in patients with psoriasis.Methods1.HaCaT cells were divided into blank control group(without PRL and IL-22);PRL group;IL-22 group;PRL+IL-22 group.The both working concentration of prolactin and IL-22 are 100 ng/ml.2.CCK-8 method was used to observe cell proliferation;ELISA method was used to detect the expression of CCL20 in cell supernatant;Real-time PCR method was used to detect the CCL20 expression of HaCaT cells.3.The expression of CCL20 in serum of patients with psoriasis was detected by ELISA,and the severity of psoriasis was analyzed by PASI.4.The serum PRL level of psoriasis patients was detected by chemiluminescence assay.5.Statistical analysis was performed using SPSS 24.0 software,and P<0.05 was considered significant.Results1.Effects of PRL and IL-22 on the proliferation of HaCaT cellsCompared with untreated group,IL-22 group,PRL group and PRL+IL-22 group showed promoting effects on the proliferation of HaCaT cells after 24-hour treatment(all P<0.05).Compared with IL-22 group and PRL group respectively,the proliferation rate of HaCaT cells were significantly high in PRL+IL-22 group(P<0.05).2.Effects of PRL and IL-22 on CCL20 expression of HaCaT cells2.1 Detection of CCL20 protein expression in HaCaT cell supernatant by ELISAThe expression levels of CCL20 in PRL,IL-22 and both groups were higher than those in blank control group,and the expression levels of CCL20 in HaCaT cells stimulated by PRL and IL-22 were higher than those in PRL or IL-22 alone stimulation group(P<0.05).2.2 Detection of CCL20-related mRNA expression in HaCaT cells stimulated by PRL and IL-22 by Real-Time PCRAccording to the amplification curve,the expression of CCL20 in PRL group,IL-22 group and PRL+IL-22 group was higher than that in blank control group,and the expression level of CCL20 in PRL+IL-22 group was higher than that in PRL or IL-22 alone stimulation group(2-ΔΔCt was greater than 2).3.Detection of serum CCL20 level of psoriasis patients by ELISAThe serum level of CCL20 in patients with psoriasis was higher than that in healthy controls(P<0.05),and the serum level of CCL20 was positively correlated with the severity of psoriasis lesions(P<0.05).4.Only 10 patients were tested for PRL in serum,only one was higher than the normal level,and the others were in the normal range.ConclusionsPRL and IL-22 can promote the proliferation of HaCaT cells and the expression of CCL20 mRNA and protein in HaCaT cells.PRL and IL-22 have synergistic effect.The level of CCL20 in serum of patients with psoriasis is positively correlated with the severity of psoriasis.The relationship between serum PRL level and psoriasis patient’s condition needs to be further studied with expanded samples.