Expression of activator protein-1 in peripheral blood mononuclear cells (PBMCs) from patients with dermatomyositis and glucocorticoid effect on the expression

Abstract

Objective To investigate the expression of activator protein-1 (AP-1) in PBMCs from patients with dermatomyositis (DM) and glucocorticoid effect on the expression.Methods PBMCs were isolated from 15 normal human controls and 20 patients (including 12 patients with primary DM who had never received glucocorticoid treatment and 8 patients with recurrent DM who had stopped glucocorticoid treatment for more than 1 month),and classified into two parts:one was cultured in RPMI 1640 medium with dexamethasone of 80 μmol/L and 10％ calf serum for 48 hours,and the other was frozen at -80 ℃ and reserved.Electrophoretic mobility shift assay (EMSA) was carried out to detect the activity of AP-1 in these cells.Results The expression (grayscale area) of AP-1 in the PBMCs from the normal controls was 4.93 ± 0.15 mm2.A significant decrease was induced by the treatment with dexamethasone in the expression (grayscale area) of AP-1 from PBMCs of patients with primary DM and those with recurrent DM (5.59 ± 0.39 vs.30.23 ± 0.49 mm2,5.69 ± 0.39 vs.34.79 ± 0.61 mm2,F =13812.64,P ＜ 0.01 ).The activity of AP-1 was statistically higher in the PBMCs from patients with recurrent DM than in those from patients with primary DM before the treatment with dexamethasone (P ＜ 0.01 ).Conclusions The enhanced activity of AP-1 may be an important factor inducing the inflammatory reaction in and recurrence of DM.Glucocorticoids may suppress the AP-1 activity to a certain degree.