Vitamin C forestalls cigarette smoke induced NF-κB activation in alveolar epithelial cells

Cigarette smoking causes cellular oxidative stress resulting in inflammatory diseases of lung wherein transcription factor NF-kappa B plays an important role. It is possible that vitamin C, an antioxidant, may prevent cigarette smoke (CS)-induced NF-kappa B activation that involves degradation of I-kappa B epsilon and nuclear translocation of c-Rel/p50 in alveolar epithelial cells. Therefore, to examine the hypothesis, we verified the effect of vitamin C on CS-induced expression of NF-kappa B driven luciferase reporter and NF-kappa B binding at its target DNA by EMSA in alveolar epithelial A549 cells. We also examined the level of I-kappa B epsilon and sub-cellular distribution of c-Rel by western blotting and immunofluorescence respectively in CSE-treated A549 cells with or without vitamin C pretreatment. We observed a significant reduction in CSE induced luciferase expression, NF-kappa B DNA binding, I-kappa B epsilon degradation and c-Rel nuclear translocation in cells pretreated with vitamin C. To further validate the result, we examined sub-cellular distribution of c-Rel in lungs of CS-exposed guinea pigs treated or untreated with vitamin C. Result showed that vitamin C treatment resulted in markedly reduced c-Rel nuclear translocation. All these results demonstrate that vitamin C prevents CS(E)-induced NF-kappa B activation and thus it could be used for the prevention of CS-induced inflammatory diseases. (c) 2013 Elsevier Ireland Ltd. All rights reserved.