PFN1 Prevents Psoriasis Pathogenesis through IκBζ Regulation.

PFN1 is an actin-binding protein that regulates actin polymerization, cell proliferation, apoptosis, angiogenesis, and carcinogenesis. Its dysregulation has been reported in diverse pathologic diseases; however, the role of PFN1 in psoriasis has not yet been elucidated. In this study, we show that PFN1 expression is increased in both skin and serum of patients with psoriasis. PFN1 was markedly expressed in the epidermis of psoriatic lesions, and its expression positively correlated with psoriasis severity. IL-17A treatment of keratinocytes increased PFN1 expression, whereas TNF-α induced PFN1 expression and secretion. In addition, knockdown of PFN1 with short hairpin RNA resulted in an altered expression of psoriasis-associated inflammatory markers, HBD2, S100A7, S100A9, and Ki-67, and recombinant PFN1 suppressed the IL-17A‒induced inflammatory response in keratinocytes. Interestingly, recombinant PFN1 also suppressed IL-17A‒induced IκBζ, an important player in immune response in psoriasis. Collectively, our results show that PFN1 acts as a negative regulator of psoriatic inflammation through the suppression of IκBζ and that the balanced level of PFN1 is important for IκBζ regulation. Thus, the expression of PFN1 can be used as a biomarker for psoriasis severity, and it can be considered as a possible target for the treatment of psoriasis.