The Regulation And Mechanism Of FXYD3 In Keratinocytes On Psoriasis

Psoriasis is a chronic inflammatory disease of the skin caused by excessive activation of the immune system.Inflammatory factors in the skin act on keratinocytes and immune cells,leading to inflammatory cell infiltration and sustained inflammatory response.Although the IL-23-IL-17A axis is considered as one of the main pathogenesis of psoriasis,psoriasis is a multi-factor,multi-step and multi-link disease,and its specific pathogenesis remains unclear.Keratinocytes are the mainly constituent cells in the epidermis.Through the various pattern recognition receptors expressed on the surface,keratinocytes sense various stimuli of the external environment,and then produce a mass of cytokines and chemokines to regulate the immune response in the skin,playing an important role in skin immune surveillance and the development of skin-related diseases.FXYD3,a specific auxiliary subunit of Na,K-ATPase,is mainly expressed in various types of epithelial cells.Studies have shown that FXYD3 has a high expression in skin tissue,but its role in skin immunity has never been reported.In this study,we aimed to investigate the regulation of FXYD3 on inflammation in keratinocytes and its mechanism.We found a significant upregulation of FXYD3 in psoriasis skin of human and mice,especially in the epidermis,so we constructed keratinocyte-specific FXYD3 deficient(K14creFXYD3f/f)C57BL/6 mice and built psoriasis mouse model by daily apply mouse skin with imiquimod cream(5%)to investigate the regulation of FXYD3 in keratinocytes on the pathogenesis and development of psoriasis.Specific knockout of FXYD3 in keratinocytes has no effect in the development of immune cells in mice,but can significantly alleviate the psoriasis-like skin inflammation,which is manifested as decreased epidermal thickness,cytokines,chemokines and less infiltration of inflammatory cells.After stimulating vitro cultured mouse primary keratinocytes and human keratinocytes NHEK cell lines with IL-17A and TNF-a,we found the absence of FXYD3 has no influence on the proliferation effect in keratinocytes induced by IL-17A,but can reduce the activation of keratinocytes and expression of antimicrobial peptides such as S100A8 and S100A9,and further reduce the expression of chemokines such as CXCL1,CXCL2,CXCL8,CXCL10 and CCL20 upon IL-17A and TNF-a stimulation.In terms of molecular mechanism,interfering the expression of FXYD3 in NHEK cell line can inhibit the activation of the NF-?B ? MAPK pathway including P3 8,ERK and JNK,which are induced by IL-17A and TNF-?.Immunoprecipitation revealed that in the NHEK cell lines,FXYD3 binds to both IL-17A receptor and TNF-a receptor.Furthermore,IL-17A and TNF-? stimulation can increase the binding of FXYD3 to the corresponding receptor.Thus,FXYD3 may regulate keratinocytes by binding to the receptor complex on the cell membrane.The above results show that FXYD3 can regulate the expression of chemokines in keratinocytes,which plays an important role in the development of psoriasis in mice.Our research has added a new understanding of the role of FXYD3 in skin innate immunity,providing a new perspective for the functional study of FXYD3 as well as a new potential target for the diagnosis and treatment of psoriasis.