Effects Of IL-24 On The Expression Ofkeratin 17 And The Proliferative Activityof HaCaT Cells

Background: The inflammatory environment of psoriasis skin lesions is the basis for pathological changes in psoriasis.It is theoretically recognized that IL-17 A and TNF-α are important inflammatory mediators that cause pathological changes in psoriasis.However,based on clinical sample research,many literatures believe that IL-24 also plays an important role in the occurrence and development of psoriasis.For this reason,many scholars of psoriasis research believe that the pathological changes of psoriasis are caused by the coordination of multiple inflammatory factors,rather than simple linear addition.For a better understanding of the effects of "IL-24" on the pathological changes of psoriasis,and to confirm whether "IL-24" and "IL-17A+TNF-α" are interdependent on the pathological changes of psoriasis,the HaCaT model was used in this study.Does IL-24 affect the pathological parameters(K17 and Ki67)of HaCaT in the context of "IL-17A+TNF-α" or not? We recognize that there is a certain gap between the research results of the cell model and the real pathological basis of psoriasis,but the results from the cell model may inspire us to better understand the basis of the real pathology of psoriasis.Objective: To investigate the effect of IL-24 on the expression of keratin 17 and proliferative activity of HaCaT cells under the background of IL-17A+TNF-α.Methods:(1)The expressions of IL-24,K17 and Ki67 in psoriasis were detected.The skin lesions of the trunk or limbs of fifteen patients with progressive and quiescent lesions of psoriasis vulgaris who were treated in the Dermatology Clinic of Wuhan Tongji Hospital and the skin tissues of the trunk or limbs of fifteen healthy people who underwent plastic surgery in Wuhan Tongji Hospital were collected.Immunohistochemistry was used to detect the expression of IL-24,K17,Ki67 in psoriasis vulgaris and normal skin tissues.And analyze the correlation between IL-24,K17 and Ki67(proliferation index).(2)RT-q PCR and Western blot were used to detect the m RNA and protein expression of K17 in HaCaT cells treated with 0ng/ml,10ng/ml,25ng/ml and 100ng/ml IL-24 for 48 hours.Among them,HaCaT cells cultured with IL-24 at 0ng/ml were used as the normal control group.(3)The m RNA and protein expression levels of K17 in HaCaT cells cultured with 100ng/ml IL-24(group A/Study Group one),50ng/ml IL-17A+100ng/ml TNF-α(group B/Consensus of psoriasis inflammation environment group)and 100ng/ml IL-24+50ng/ml IL-17A+100ng/ml TNF-α(group C/Study Group two)for 48 h were evaluated by RT-q PCR and Western Blot,respectively.(4)HaCaT cells were cultured in the medium containing group A,group B and group C(group the same as before)for 24 h,48h and 72 h respectively by CCK8 technique.The proliferation activity of HaCaT cells was evaluated by OD450 value.Results:(1)The results of immunohistochemistry showed that the expression levels of IL-24,K17 and Ki67 in psoriatic lesions were significantly higher than those in healthy skin.Correlation analysis of IL-24,K17 and Ki67: IL-24 and Ki67 or K17 and Ki67 or IL-24 and K17 are all positively correlated,that is,the higher the expression of IL-24 and K17,the stronger the proliferation activity of keratinocytes.(2)The results of RT-q PCR and Western blot showed that,compared with the normal control group,the expression of K17 m RNA and protein in the culture group with10ng/ml and 25ng/ml IL-24 medium had no significant difference,but the expression of K17 m RNA and protein in the culture group with 100ng/ml IL-24 medium were not increased.(3)The results of RT-q PCR and Western blot showed that compared with the normal control group,the expression of K17 m RNA and protein in group A were not increased,the expression of K17 m RNA in group B increased,and the expression of K17 protein in group B was not increased,while the expression of K17 m RNA and protein in group C were significantly increased.(4)The results of CCK8 showed that compared with the normal control group,the OD450 value of HaCaT cells was not increased after culturing HaCaT cells in group A medium for 48 h and72h.After culturing HaCaT cells in group B medium for 48 h and 72 h,the OD450 value increased.After culturing HaCaT cells in group C medium for 48 h and 72 h,the OD450 value increased significantly.Conclusions: Stimulating HaCaT cells with IL-24 alone can not up-regulate the expression of keratin 17,but IL-24 can significantly promote the expression of keratin17 in HaCaT cells and enhance the proliferation activity of HaCaT cells under the background of IL-17A+TNF-α.