Expression of Krox‐20 is Increased in Psoriasis

Abstract

Psoriasis is a common and chronic inflammatory skin disease that afflicts 2–3% of the world population. There is no cure and the precise cause of psoriasis is unknown. Cytokines however, have been established as critical mediators in the immunopathogenesis of psoriasis. EGR‐2 is an immediate early serum response gene that codes for Krox‐20, a zinc finger transcription factors that is important in resisting TGF‐? mediated apoptosis. The aim of this study was to evaluate Krox‐20 expression in epidermal keratinocytes in psoriasis where aberrant response to TGF‐? signaling has been shown to occur. Formalin‐fixed paraffin‐embedded tissue (N = 38) including nine psoriatic plaques (PP), nine lichen planus (LP), ten lichen simplex chronicus (LSC), and ten normal skin (NS) were evaluated for expression of Krox‐20 by immunohistochemistry. Frequency and relative intensity of nuclear labeling were evaluated. Strong and diffuse nuclear labeling of keratinocytes was observed in all PP and LSC. The frequency of labeling was significantly greater (p < 0.05) in PP and LSC compared to NS. Lichen planus tended toward absent to weak nuclear labeling of keratinocytes. The increased frequency of Krox‐20 expression in PP and LSC may lead to resistance of TGF‐? mediated apoptosis and contribute to epidermal hyperplasia common to these disorders.