Tumor necrosis factor-α-converting enzyme as a potential mediator of the influence of smoking on the response to treatment with narrowband ultraviolet B in psoriasis patients

Purpose The aim of the study was to analyze the relationship between smoking and the treatment with narrowband ultraviolet B (NB-UVB) in psoriasis patients and to examine the role of the soluble tumor necrosis factor-alpha receptor type one (sTNF-R1) in plasma and that of TNF-alpha-converting enzyme (TACE) released from peripheral blood mononuclear cells (PBMC) in this relationship. Methods The study has been conducted among 45 inpatients with plaque-type psoriasis vulgaris and 36 inpatients with other chronic inflammatory skin disorders from similar social background (controls). Taking into account the number of cigarettes smoked daily and the duration of smoking, subjects were classified as mild, moderate and heavy smokers. The severity of psoriasis was assessed using psoriasis area and severity index (PASI) score, concentrations of sTNF-R1 and TACE (expressed in ng/ml) - with quantitative sandwich enzyme immunoassays before (T-0) and after 20 NB-UVB irradiations (T-20). Results The pretreatment concentration of sTNF-R1 was 2.55 +/- 0.17 in patients and 1.79 +/- 0.13 in controls (P < 0.05) and that of TACE - 2.62 +/- 0.34 and 1.29 +/- 0.25, P < 0.05, respectively. PASI score correlated with sTNF-R1 and with TACE concentrations (R=0.40 and R=0.38, P < 0.05, respectively). PASI score, sTNF-R1 and TACE concentrations were similar in mild, moderate and in heavy smokers. PASI score and TACE concentration declined significantly after treatment in three groups; the lowest TACE concentration at T-20 was noticed in mild smokers, the highest in heavy smokers (0.86 +/- 0.26 and 1.91 +/- 0.20, P < 0.05, respectively). The post-treatment PASI score correlated with the intensity of smoking and with TACE concentration (R=0.50 and R=0.47, P < 0.05, respectively). The strong correlation between the pretreatment TACE concentration and the treatment outcome was observed in heavy smokers (R=0.63, P < 0.05). Conclusions The baseline TACE concentration in PBMC may be of value in predicting the response to the treatment with NB-UVB in smoking psoriasis patients. Smoking may adversely influence this treatment and TACE may be one of mediators in this influence.