Regulation of NF-κB and ICAM-1 expression in human airway epithelial cells

The aim of this study was to elucidate the redox regulation of cytokine-induced NF-kappaB activation and NF-kappaB mediated gene induction in A549 cells and primary cultures of human airway epithelial cells. In A549 cells, Western blot analysis showed transient depletion of I kappaB alpha after 15 min IL-1 beta treatment followed by its reappearance after 60 min, indicating efficient NF-kappaB-driven gone induction. A similar pattern was observed in primary epithelial cells however, the kinetics were slower and depletion was less. In primary airway epithelial cells I kappaB alpha levels were 59.8 +/- 8.5% of control following 30 min treatment with IL-1 beta and in A549 cells 29.1 8.5% of control following 15 min IL-1 beta treatment. Cytokine-induced I kappaB alpha depletion was associated with NF-kappaB nuclear accumulation and subsequent resynthesis of I kappaB alpha and upregulation of ICAM-1 in both cell types. The antioxidant, NAC (20 mM) had no effect on the kinetics of cytokine-induced I kappaB alpha depletion or NF-kappaB p65 nuclear translocation in either cell type and failed to influence kappaB dependent I kappaB alpha resynthesis. H2O2 treatment alone or in combination with cytokines had no significant effects on I kappaB alpha depletion, NF-kappaB p65 nuclear translocation or ICAM-1 expression in either cell type but did cause significant activation or p38 MAPK. These results suggest that cytokine-induced NF-kappaB activation in cultured human airway epithelial cells does not involve an NAC-sensitive oxidant stress and that H2O2-induced oxidant stress does not result in effective NF-kappaB activation and NF-kappaB mediated gene induction.