Abstract:

Objective To explore the role of IL-18 in the pathogenesis of chronic eczema. Methods Twenty-seven patients with chronic eczema were enrolled into this study along with 12 normal human controls. The severity of eczema was evaluated by eczema area and severity index （EASI） in patients. Skin specimens and vein blood samples were obtained from all the subjects. Reverse-transcription PCR was performed to detect the mRNA expression of IL-18 and IFN-γ in the skin tissue, and enzyme linked immunosorbent assay （ELISA） to measure the protein expression of IL-18 and IFN-γ in the sera of these subjects. Results The mRNA expression level in patients and controls was 1.04 ± 0.29 pg/mL and 0.52 ± 0.15 pg/mL for IL-18, respectively, 0.96 ± 0.34 pg/mL and 0.47 ± 0.12 pg/mL for IFN-γ, respectively; a significant increase was observed in the mRNA expression level of both IFN-γ and IL-18 in the patients than in the controls （both P < 0.01）. Moreover, the mRNA expression level of both IFN-γ and IL-18 positively correlated with the severity of eczema in patients （r = 0.737, 0.883, both P < 0.01）. The protein expression level of IL-18 and IFN-γ was 475.8 ± 59.4 pg/mL and 10.1 ± 7.0 pg/mL, respectively, in the patients, 123.6 ± 29.5 pg/mL and 11.1 ± 3.4 pg/mL, respectively, in the controls; a statistical difference was observed in the protein expression level of IL-18 （P < 0.01）, but not in that of IFN-γ （P > 0.01）, between the patients and controls. No significant correlation was observed between the serum level of IL-18 or IFN-γ and sererity of eczema in the patients （both P > 0.01）. Conclusions IL-18 may be involved in the pathogenesis of chronic eczema. Also, in local lesions, IL-18 seems to correlate with the induction of production of Th1 type cytokines, such as IFN-γ, which could subsequently mediate hypersensitivity response.

Key words: Chronic eczema;Interleukin 18;Interferon γ