Interleukin-17 and interleukin-23 mRNA expressions in peripheral blood of patients with psoriasis vulgaris and their correlations with disease severity

Abstract

Objective To compare the mRNA expressions of interleukin (IL)-17 and IL-23 in peripheral blood of patients with psoriasis vulgaris versus healthy individuals,assess the relationship of these parameters with psoriasis area and severity index (PASI) score,and to investigate the therapeutic mechanisms of total glucosides of peony (TGP) for psoriasis vulgaris.Methods Fifty patients with psoriasis vulgaris and 40 healthy individuals were enrolled in this study.Of these patients,42 were treated with TGP of 600-900 mg twice a day for 8 weeks.Blood samples were obtained from all the healthy individuals,50 patients before treatment,42 patients after 4-week treatment,and 23 patients after 8-week treatment.Real-time fluorescence-based quantitative reverse transcription PCR (RT-PCR) was used to determine the mRNA expression levels of IL-17 and IL-23 in the blood samples.The severity of psoriasis was evaluated using PASI score before and after the treatment.Statistical analysis was done by t test,rank sum test,and Pearson correlation analysis using the SPSS16.0 software.Results The IL-17 and IL-23 mRNA expression levels (given in △Ct value) in the patients before treatment were significantly higher than those in the healthy controls (IL-17,-5.32 ± 0.80 vs.2.79 ± 0.76,t =47.71,P ＜ 0.05; IL-23,-5.43 ± 0.68 vs.-3.77 ± 0.86,t =10.38,P ＜ 0.05),and positively correlated with the PASI score (r =0.61,0.52 respectively,both P ＜ 0.05).A significant decrease was observed in the mRNA expression levels of IL-17 and IL-23 as well as PASI score in the 42 patients after 4-week treatment with TGP compared with those before treatment(IL-17,-2.24 ± 0.61 vs.-5.30 ± 0.78,t =20.40,P ＜ 0.05; IL-23,-1.97 ± 0.74 vs.-5.44 ± 0.68,t =21.69,P ＜ 0.05; PASI,5.8 ± 2.7 vs.9.4 ± 4.2,t =4.68,P ＜ 0.05),and in the 23 patients after 8-week treatment compared with those after 4-wek treatment(IL-17,-1.51 ± 0.78 vs.-2.21 ± 0.59,t =3.50,P ＜ 0.05; IL-23,-1.27 ± 0.81 vs.-1.89 ± 0.72,t =2.70,P＜ 0.05; PASI,3.8 ± 1.8 vs.7.3 ± 2.5,t =5.47,P＜ 0.05).Conclusions It seems that both IL-17 and IL-23 are involved in the pathogenesis of psoriasis vulgaris,and TGP treatment can reduce the mRNA expression levels of IL-17 and IL-23 as well as PASI score in patients with psoriasis vulgaris. Key words: Psoriasis; Interleukin-17; Interleukin-23; Psoriasis area and severity index