The expression and role of krüppel-like factor 4 in psoriasis

Krüppel-like factor 4 (KLF4) is a transcription factor that regulates a diverse array of cellular processes, including development, differentiation, proliferation, and apoptosis. Although its function in keratinocytes has been widely studied, its exact role in psoriasis has not been elucidated. We designed this study to investigate epidermal expression levels of KLF4 and the change in KLF4 expression after treatment in patients with psoriasis. We compared the expression levels of KLF4 in the basal, suprabasal, and superficial epidermal layers, in psoriatic lesional, non-lesional, and normal skin, using an immunoreactivity intensity distribution index (IRIDI). In addition, we measured the change in KLF4 expression on the basis of the IRIDI and by reverse transcription polymerase chain reaction (RT-PCR) analysis after treatment. The combined IRIDI scores in psoriatic lesional skin were significantly higher than the scores in both non-lesional and normal skin. The psoriatic epidermis, particularly the suprabasal layer, showed a significantly increased IRIDI score compared to that of non-lesional and normal skin, which was significantly decreased after treatment. RT-PCR analysis exhibited a slight increase in KLF4 mRNA expression level after treatment; however, this increase was not significant. These data indicate that KLF4 could regulate epidermal proliferation and differentiation. Moreover, we believe that KLF4 may play an important role in the physiological reaction to counteract abnormal differentiation and proliferation of keratinocytes.