Objective: To study the effects of erythromycin on Hydrogen peroxide (H2O2)-induced interleukin-8 synthesis and regulation of glutathione in human bronchial epithelial cells.
Methods: Human bronchial epithelial (16HBE) growth curve was recorded by MTT, cells were divided into three groups (1) control (incubation for 24, 36, 48) (2) H2O2 (Pre-incubation for 24, 36, 48 h before adding H2O2 (3) H2O2 + EM (Pre-incubation EM for 24, 36, 48 h before adding H2O2). IL-8 levels were measured in culture supernatants by ELISA, activation of transcription factor NF-kappaB and AP-1 in HBE was evaluated by Electrophoretic mobility shift assay (EMSA). Intracellular GSH and Gamma-GCS concentrations were measured by spectrophotometric assay, gamma-GCS-HS protein were determined by Western blot.
Results: Erythromycin (1 microg/ml, 10 microg/ml) and H2O2 (0.01 mM, 0.1 mM) have no effects on cell growth, Preincubation with EM (5 microg/ml) for 36 h and 48 h significantly inhibit H2O2 (0.01 mmol/L) induced increase of IL-8 levels in HBE supernatants, in the mean time decrease the expression of NF-kB and AP-1. Preincubation with EM (5 microg/ml) for 48 h significantly inhibit H2O2 (0.01 mmol/L) induced increase of gamma-GCS levels, gamma-GCS-HS protein expression and AP-1 binding of gamma-GCS-HS promoter in HBE. However GSH and gamma-GCS-HS protein expression in EM + H2O2 group significantly higher than those in control group.
Conclusion: Erythromycin inhibits oxidant-mediated IL-8 levels through down-regulation of NF-kB and AP-1 binding in HBE, which can further influence the synthesis of GSH and expression gamma-GCS in HBE.