Expression Characteristics Of IL-21 In Psoriasis And Its Effect On The Expression Of Keratin, IL-17 And IL-10

Objective:We aim to investigate the characteristics of interleukin(IL)-21 in psoriatic mice model inducing by imiquimod(IMQ),and investigate the effect of IL-21 on the expression of keratin,IL-17 and IL-10.Method:30 8-week-old BALB/c male mice were randomly divided into 6 groups:blank group,model group,acitretin group,sterilized water(SW)group,IL-21 injection group and SW injection group.After depilation on the back of all mice,the mice in the blank group were smeared with appropriate amount of Vaseline on the back skin every day for 7 days,and the mice in the model group,acitretin group and SW group were smeared with 5%IMQ cream 62.5 mg on the back skin every day for 7 days.At the same time,acitretin group and SW group were intragastrically infused with acitretin and SW for 7 days,respectively.The mice in the IL-21 injection group were subcutaneously injected with IL-21 protein 500ng(50?l)daily,and the mice in the SW injection group were subcutaneously injected with 50?l SW every day for 4 days.The skin lesions of all mice were photographed 24 hours after the last administration,and the psoriasis area and index(PASI)score was calculated.Then the mice were killed and the histopathological manifestations of mice in each group were observed by HE staining.The expressions of IL-21 and keratin K1,K5,K10,K17 were detected by immunofluorescence technique,and the expressions of IL-21,IL-17 A and IL-10 in skin lesions were detected by RT-PCR.Results:In the model group,there were obvious scales,erythema and skin thickening on the back of the mice.PASI score,epidermal thickness,keratin and the expression of IL-17A and IL-21 were significantly increased(P<0.0001),while the expression of IL-10 was down-regulated(P<0.0001).Compared with the SW group,the clinical manifestations of mice in the acitretin group were alleviated.PASI score,epidermal thickness,keratin and the expression of IL-17A and IL-21 were decreased(P<0.0001),and the expression of IL-10 was increased(P<0.0001).There was a positive correlation between IL-21 and the severity of psoriasis(r=0.8200,P<0.0001).The epidermis thickness and the expression of IL-17A and IL-21 in IL-21 injection group were higher than those in SW injection group(P<0.0001),but there was no significant difference in PASI score and IL-10(P>0.05).Conclusion:1.The expression of IL-21 was increased in psoriatic mice,which was positively correlated with the severity of psoriasis.2.IL-21 promotes the proliferation of keratinocytes and up-regulates the expression of IL-17A,which aggravates the inflammatory reaction of psoriasis,but has no significant effect on the expression of keratin and IL-10.