The Role Of Keratin 17 In Imiquimod-Induced Psoriasis-Like Mouse Model

Psoriasis is a common chronic skin disease typically characterized by sharply erythematous plaques in different sizes and shapes with silvery scales.The recurrence of the disease brings great trouble to patients physically and mentally.Years of substantial advances have been made to elucidating its molecular pathogenesis.However,the major parts remain unsolved.Recent studies believe that disorder of local microenvironment,setting by genetic and environmental factors along with innate and adaptive immune system,plays an important role in the pathogenesis of psoriasis.This complex interplay initiates a cascade of the disease event and induces intricate cross-talk between keratinocytes and immune cells,the process of which finally maintains the inflammatory milieu and aggravates the disease condition.Hence,great significance will be made to explore the intercellular interactions in psoriatic lesions for revealing the mechanisms of psoriasis.Keratin 17(K17)is a cytoskeletal protein,maintaining the framework of keratinocytes.K17 is highly expressed in psoriatic epidermis and its high-expressing levelis positively related to the severity of psoriasis.Based on our previous work,our group firstly brought forward K17/T-cell/cytokines autoimmune positive feedback loop,indicating that keratinocytes can be activated and highly express K17 under the circumstances of stress,infection or injury.In turn,K17 regulates keratinocytes in secreting of CXCL1 which recruits neutrophils to migrate to the lesions,then the migrated neutrophils help to expose epitopes of K17 that activate T cells to release cytokines such as IFN-?,IL-17 A and IL-22.These cytokines could then induce high expression of K17 in keratinocytes and the cascade goes on to become a vicious loop.As K17 playing such a vital role in the pathogenesis of psoriasis,our group decided to employ K17-knockout mice to testify the effect of K17 and finally clarify its significance.ObjectiveTo explore the role of K17 in the pathogenesis of psoriasis and its immune-molecular mechanism by employing the imiquimod-induced psoriasis-like K17-knockout mice model and to testify the effect of K17-si RNA as a treatment in dealing with psoriasis.Method1.The imiquimod-induced psoriasis-like mice model was established with K17-knockout mice.Appearance was observed and H&E staining was performed to evaluate the severity of the disease induced by imiquimod;Real-time PCR and flow cytometry were applied to test the expression of cytokines and chemokines in keratinocytes and the infiltration of neutrophils respectively.2.K17 si RNA were designed to down-regulate the expression of K17 in the epidermis of mice before applying the imiquimod for the establishment of imiquimod-induced psoriasis-like mice model.Appearance was observed and H&E staining was performed to evaluate the severity of the disease;Real-time PCR and flow cytometry were applied to test the expression of cytokines and chemokines in keratinocytes and the infiltration of neutrophils respectively.Res?lts1.Appearance and H&E staining showed an obvious relief of psoriatic lesions,decreased thickness of epidermis and blood capillaries shrinking in numbers in K17-knockout mice group.2.Real-time PCR revealed that the expression of cytokines(IL-6,IL-8,IL-22,VEGF)and chemokines(CXCL-1,CXCR-3,CCR-4 CCL-20,CCL-22,CCR-10)were significantly down-regulated in K17-knockout mice group.3.Flow cytometry showed less neutrophil infiltration in K17-knockout mice group.4.After topical application of K17 si RNA,the results from the imiquimod-induced psoriasis-like mice model group coincided with that from the K17-knockout mice group,all of which were the obvious relief of psoriatic lesions,decreased thickness of epidermis,less blood capillaries,down-regulated cytokines(IL-6,IL-8,IL-22,VEGF)and chemokines(CXCL-1,CXCR-3,CCR-4 CCL-20,CCL-22,CCR-10)and less neutrophil infiltration after the inhibition of K17 expression.Concl?sionWith the help of K17-knockout mice,we testified that aberrantly highly expressed K17 in the psoriatic lesions may manipulate the pathogenesis of psoriasis by regulating the keratinocytes in expressing various cytokines and chemokines,and also by promoting the local angiogenesis and neutrophil infiltration.Meanwhile,the results firstly demonstrated the significant importance of K17 as a therapeutic target in dealing with psoriasis.