Ann Dermatol.  2014 Dec;26(6):675-680. 10.5021/ad.2014.26.6.675.

The Expression and Role of Kruppel-Like Factor 4 in Psoriasis

• Kim KJ
• Park S
• Park YH
• Ku SH
• Cho EB
• Park EJ
• Kim KH

• KMID: 2264860
• DOI: http://doi.org/10.5021/ad.2014.26.6.675

Abstract

BACKGROUND
Kruppel-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.
OBJECTIVE
We designed this study to investigate epidermal expression levels of KLF4 and the change in KLF4 expression after treatment in patients with psoriasis.
METHODS
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.
RESULTS
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.
CONCLUSION
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.

Keyword

Kruppel-like factor 4; Psoriasis

MeSH Terms

Apoptosis
Epidermis
Humans
Keratinocytes
Polymerase Chain Reaction
Psoriasis*
Reverse Transcription
RNA, Messenger
Skin
Transcription Factors
RNA, Messenger
Transcription Factors

Figure

• 

  Fig. 1 Immunohistochemical staining for KLF4. (A) Normal skin specimen showing KLF4 expression in the basal layer. (B) Non-lesional skin of a patient with psoriasis, showing an increased number of KLF4-positive cells compared to that in a normal skin specimen. (C) Psoriasis plaque showing increased KLF4 expression. KLF4 expression in psoriatic lesional skin was significantly higher compared to that in both non-lesional and normal skin. (D) After treatment, KLF4 expression decreased in suprabasal layer (A, B, D: ×200; C: ×100).

• 

  Fig. 2 (A) Representative RT-PCR analysis of KLF4 and GAPDH (control) before and after treatment. After treatment, the intensity of KLF4 mRNA expression was increased compared to that in the control. (B) The relative intensity of KLF4 mRNA expression was slightly, but not significantly, increased.

• 

  Fig. 3 Reduction in the proliferation of HaCaT cells after KLF4 knockdown. Three siRNA probes (A, B, and C) were evaluated, all of which showed a decreasing tendency in proliferation index (PI); however, this decrease and the margin of decrease between the groups were not statistically significant.

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