Soluble tumour necrosis factor-alpha receptor type 1 as a biomarker of response to phototherapy in patients with psoriasis

The purpose of the study was to analyze the relationship between the serum concentration of soluble tumour necrosis factor-alpha type 1 (sTNF-R1), the severity of plaque-type psoriasis and therapeutic response. We compared sTNF-R1 in 25 patients treated with narrowband ultraviolet B (NB-UVB) radiation and 25 patients treated with systemic photochemotherapy (psoralen plus UVA-PUVA). The pretreatment Psoriasis Area and Severity Index (PASI) score and sTNF-R1 concentration were 16.32 +/- 5.26 and 1.99 +/- 0.40 ng ml(-1), respectively, in the group treated with NB-UVB, and 17.22 +/- 3.48 and 2.07 +/- 0.31 ng ml(-1), respectively, in the group treated with PUVA. The concentration of sTNF-R1 in healthy controls was 1.49 +/- 0.34 ng ml(-1) (p < 0.05 compared with patients with psoriasis). The pretreatment PASI score correlated with sTNF-R1 in both treatment groups (r = 0.46 and r = 0.44, p<0.05). NB-UVB and PUVA gave similar therapeutic effects (the PASI score after 20 treatments was 4.42 +/- 1.67 in the NB-UVB-treated group and 5.55 +/- 2.10 in PUVA-treated patients); however, the sTNF-R1 concentration at the same time differed significantly: 1.52 +/- 0.37 ng ml(-1) and 1.98 +/- 0.39 ng ml(-1) (p<0.001), respectively. Moreover, the decline in sTNF-R1 in both treatment groups was significant only in patients in whom the duration of skin lesions was less than 3 months. The results suggest that the value of serum sTNF-R1 concentration as a marker of response to phototherapy may depend on duration of skin lesions and the treatment method.