Investigation of the effects of dexamethasone on STAT1 in monocytes of patients with SLE
Objective To explore the effects of dexamethasone on the DNA-binding activity of signal transducer and activator of transcription 1(STAT1)in the nuclear extracts derived from peripheral monocytes of patients with systemic lupus erythematosus(SLE). Methods Five patients were included. After separated from peripheral bloods,monocytes were treated with dexamethasone(10 -6 mol/L) for 24 hours,and then the nuclear proteins were isolated. The DNA binding activity of STAT1 was examined by electrophoretic mobility shift assays (EMSA). Results Dexamethasone significantly inhibited the DNA-binding activity of STAT1 in peripheral blood monocytes from patients with SLE,and the DNA-binding activity of STAT1 was suppressed 60% at the dexamethasone concentration of 10 -6 mol/L(P0.05). The inhibitory effects could be detected at 8 hours,became significant at 12 hours and lasted longer than 48 hours after the addition of dexamethasone. Conclusion Dexamethasone significantly inhibites the DNA-binding activity of transcription factor STAT1,which may explain immune suppressive function of dexamethasone.