Gene expression of cytokines in atopic eczema before and after ultraviolet A1 phototherapy

Summary Background Atopic eczema (AE) is a common pruritic and chronically relapsing inflammatory skin disease in which cytokines seem to represent important factors in the pathogenesis. Objectives We aimed to investigate cytokine mRNA expression in the skin of patients with AE who underwent a course of ultraviolet A1 (UVA1) phototherapy. Methods We studied 21 patients diagnosed with extrinsic AE who were treated with a 6‐week course of UVA1 phototherapy. Skin biopsies were taken from healthy controls (n = 18) and patients with AE at baseline and after the last UVA1 exposure. Quantitative real‐time reverse transcriptase‐polymerase chain reaction was performed for interleukin (IL)‐4, IL‐5, IL‐10, IL‐13 and IL‐31. Results A significant reduction of the clinical scores was observed after treatment with UVA1. Except for IL‐4, cytokine mRNA expression was significantly increased prior to phototherapy when compared with controls. mRNA levels of IL‐4 and IL‐10 before UVA1 did not significantly differ from levels observed after UVA1. However, a significant decrease of IL‐5, IL‐13 and IL‐31 mRNA expression was observed following UVA1 treatment. IL‐31 mRNA levels were even adjusted to the levels of healthy controls. Conclusions We have shown that the resolution of extrinsic AE lesions following phototherapy is accompanied by significant reduction of mRNA expression of IL‐5, IL‐13 and IL‐31, supporting current concepts that these cytokines play a crucial role in the pathogenesis of extrinsic AE and possibly represent targets for phototherapy.