1. ^*Department of Dermatology, Marselisborg Hospital, University of Aarhus, Aarhus C, Denmark
2. ^†Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M, Denmark

Correspondence: Claus Johansen, PhD, Department of Dermatology, Aarhus University Hospital, University of Aarhus, P. P. Orumsgade 11, DK-8000 Aarhus C, Denmark. Email: clausoglotte@hotmail.com

Received 7 September 2004; Revised 23 December 2004; Accepted 30 January 2005; Published online 3 June 2005.

Abstract

Nuclear factor-B (NF-B) is an inducible nuclear transcription factor regulating a range of cellular processes. An imbalance of the DNA binding activity of NF-B may, therefore, be part of the pathophysiological mechanisms in psoriasis. The purpose of this study was to determine the NF-B DNA binding activity in psoriatic skin using three different B sites and to determine how DNA binding activity was modulated by the anti-psoriatic drug calcipotriol. By electrophoretic mobility shift assay, we demonstrated that the NF-B DNA binding to the p53 B site was decreased, whereas the NF-B DNA binding to the interleukin-8 (IL-8) B site was increased in lesional psoriatic skin compared with non-lesional psoriatic skin. No regulation was seen on the NF-B DNA binding to the major histocompatibility complex class I B site. These changes were paralleled by a similar decrease in p53 expression and an increase in IL-8 expression in involved psoriatic skin compared with uninvolved skin as determined by quantitative RT-PCR. The alteration in NF-B DNA binding activity was neither accompanied by any change in the expression of the inhibitor B (IB) kinases, IKK, IKK, and IKK nor in the expression of the NF-B inhibitor proteins, IB and IB. Immunofluorescence analysis revealed that p65 was sequestered in the cytoplasm of keratinocytes, whereas p50 exhibited a cytoplasmic as well as a nuclear localization. Interestingly, this distribution of p50 and p65 was similar in lesional and non-lesional psoriatic skin. Topical application of calcipotriol to lesional psoriatic skin for 4 d resulted in increased NF-B binding to the p53 B site and decreased NF-B binding to the IL-8 B site. Taken together, our data demonstrate that the NF-B DNA binding activity is regulated in a specific manner in psoriatic skin depending on the B sites investigated, and that topical treatment of psoriatic skin normalizes the abnormal NF-B binding activity seen in lesional psoriatic skin.