Increased expression of interleukin-23 p19 mRNA in erythema nodosum-like lesions of Behçet's disease.

BACKGROUND: Behçet's disease (BD) is a multisystemic chronic inflammatory disease with unknown aetiology. Interleukin (IL)-12, which is involved in the pathogenesis of BD, is a 70-kDa cytokine made of p35 and p40 subunits. Recently, IL-23, which is composed of a p19 subunit and a shared p40 subunit of IL-12, was discovered; as a consequence, this raises the need to re-examine previous IL-12 reports to determine whether IL-23 is also involved in BD pathogenesis.

OBJECTIVES: To determine whether there are changes in IL-23 in skin lesions and sera of patients with BD.

METHODS: For quantitative reverse transcription-polymerase chain reaction, the total cellular RNA of erythema nodosum (EN)-like skin lesions from patients with BD, psoriasis skin lesions and skin biopsy samples from normal individuals was analysed. To determine cytokine levels, sera from patients with BD and normal individuals were analysed.

RESULTS: Increased IL-23 p19 mRNA levels were observed for both EN-like lesions of patients with BD and skin lesions of patients with psoriasis compared with normal individuals. Although we observed an elevation of IL-12/23 p40 mRNA expression in the BD lesions, this was not significant. Moreover, the levels of IL-12 p35 mRNA in BD lesions were also not significantly different from the levels in normal control skin. In addition, no significant changes were detected in serum IL-12 and IL-23 levels between patients with BD and normal control individuals, or in patients with BD before and after treatment.

CONCLUSIONS: Increased expression of IL-23 p19 mRNA in BD lesions suggests that IL-23 may be associated with the development of the EN-like lesions in patients with active BD.