JEADV ISSN 1468-3083 72 JEADV 2007, 21, 72–78 © 2006 European Academy of Dermatology and Venereology Blackwell Publishing Ltd ORIGINAL ARTICLE Vascular adhesion protein-1 (VAP-1) is overexpressed in psoriatic patients A Madej,† A Reich,*† A Orda,‡ JC Szepietowski† †Department of Dermatology, Venereology and Allergology, University of Medicine, Wroc¬aw, ‡Radioimmunology Laboratory, Department of Cardiology, University of Medicine, Wroc¬aw, Poland Keywords adhesion molecules, inflammation, leucocytes, psoriasis, vascular adhesion protein-1 *Corresponding author, Department of Dermatology, Venereology and Allergology, University of Medicine, Ul, Chalubinskiego 1, 50-368 Wroc¬aw, Poland, tel. +48 71 7842288; fax +48 71 3270942; E-mail: adi_medicalis@go2.pl Received: 23 September 2005, accepted 27 January 2006 DOI: 10.1111/j.1468-3083.2006.01869.x Abstract Background Vascular adhesion protein (VAP)-1 is an adhesion molecule with an enzymatic activity that partakes in the migration process of lymphocytes. Objectives The aim of this study was to investigate the expression of VAP-1 in the skin and serum of psoriatic patients. Material and methods Seventy-one patients suffering from psoriasis aged between 23 and 89 years were included in the study. The mean psoriasis severity assessed according to the psoriasis area and severity index was 14.2 ± 9.6 points. The soluble VAP-1 serum concentration was evaluated by ELISA and VAP-1 expression in the skin (nine patients) immunohistochemically. Results The serum concentration of soluble VAP-1 was significantly higher in psoriatic patients than in healthy controls (403.4 ± 130.8 ng/mL vs. 246.4 ± 68.0 ng/mL; P < 0.0001). No significant relationships were found between sVAP-1 concentration and studied clinical parameters, except the presence of pruritus. Mean number of VAP-1 positive vessels in psoriatic skin, both lesional (19.8 ± 1.4) and non-lesional (9.4 ± 1.4), was significantly higher than in healthy skin (5.4 ± 1.5; P < 0.005). Lesional psoriatic skin demonstrated significantly more VAP-1 positive vessels than non-lesional skin (P < 0.01). Conclusions Significant overexpression of VAP-1 in both lesional and non- lesional psoriatic skin and higher serum level of soluble VAP-1 in psoriatic patients may indicate the role of VAP-1 in chronic inflammation occurring in psoriasis. However, because of lack of correlation between soluble VAP-1 serum levels and psoriasis severity this hypothesis needs further investigation. Introduction Psoriasis is a chronic, inflammatory skin disorder with a shortening of keratinocyte turn-over time and with dermal infiltrations composed of lymphocytes and neutro- phils. 1 The first critical step in lymphocyte migration from the circulation to peripheral tissue is the adhesion of lymphocytes to vascular endothelium. Migration of lymphocytes to the skin is mediated by several adhesion molecules on the endothelial cells and leucocytes. 2 In the late 1980s vascular adhesion protein (VAP)-1 was found to be an adhesion molecule that takes part in the inflammatory process of arthritis. 3 VAP-1 was also proved to be important for lymphocyte adherence to vessels in inflamed skin and gut, and in heart during ischaemia reperfusion. 2,4,5 VAP-1 is a heavily sialylated glycoprotein which consists of two identical monomeric subunits of 90 kDa. 6 It is a type-2 membrane protein consisting of 764 amino acids, with a short cytoplasmatic N-terminus, a single transmembrane domain and a large extracellular domain. 7 The VAP-1 sequence has significant identity to semicarbazide-sensitive amine oxidases (SSAO), which catalyse oxidative deamination of primary amines, 7,8 and it has been clearly demonstrated that VAP-1 displays SSAO activity. 9 The enzymatic activity is probably responsible for the close adherence of lymphocytes to the epithelium. 7 Animal studies have demonstrated that VAP-1 expression on cell membrane is induced only by inflammation. 7,10 There