Abstract:

Objective To evaluate the in vitro effect of heat shock protein 70 （HSP70） on interleukin-6 （IL-6） expression by cultured fibroblasts from psoriasis vulgaris lesions（PFbs）. Methods Fibroblasts were isolated from the lesions of patients with psoriasis vulgaris and subjected to a primary culture. After 3 to 5 passages of culture, the fibroblasts were collected and used in the next experiment. Some PFbs were cultured with different concentrations （5, 10, 20, 30 mg/L） of HSP70 for 48 hours, or with HSP70 of 30 mg/L for different durations （3, 6, 12, 24, 48, 72 hours）; some PFbs were incubated with HSP70 of 30 mg/L for 24 hours after pretreatment with pyrrolidine dithiocarbamate（PDTC, a specific inhibitor of nuclear factor-kappa B） for 30 minutes. PFbs receiving no treatment served as the control. Enzyme-linked immunosorbent assay （ELISA） and semi-quantitative reverse transcription PCR were performed to measure the IL-6 protein expression in culture supernatant and IL-6 mRNA expression by PFbs, respectively. Differences in the expression of IL-6 protein and mRNA between PFbs receiving different treatment were analyzed by using t test and Dunnett′s t test. Results HSP70 significantly increased both protein production and mRNA expression of IL-6 in a time（0－48 h）- and dose（5－30 mg/L）-dependent manner. The expression levels of supernatant IL-6 protein and IL-6 mRNA were significantly higher in the PFbs treated with HSP70 of 10 mg/L for 48 hours than untreated PFbs （（75.2 ± 15.4） ng/L vs. （47.2 ± 10.6） ng/L, 0.439 ± 0.093 vs. 0.249 ± 0.069, both P ＜ 0.05）. A significant increase was observed as early as 6 hours in the level of IL-6 mRNA after the treatment with HSP70 of 30 mg/L, and 12 hours in the level of supernatant IL-6 protein. Decreased supernatant IL-6 protein and IL-6 mRNA were noted for PFbs treated with PDTC and HSP70 of 30 mg/L compared with untreated PFbs （（42.23 ± 9.41） ng/L vs. （68.40 ± 14.43） ng/L, 0.144 ± 0.048 vs. 0.295 ± 0.081, both P < 0.05）. Conclusion HSP70 may increase the expression of IL-6 mRNA and protein by cultured PFbs via the nuclear factor-kappa B pathway.

Key words: Interleukin-6