NRF2 activation is involved in preventing oxidative stress (OS) induced chloride current alteration in human lung cells

The lung tissue is one of the main targets of OS due to external sources and respiratory activity. Thus, we were interest to understand if the alteration of lung epithelial cells redox homeostasis affected Cl current and if NRF2, which transcribes for the phase 2 “antioxidants” enzymes, modulated it. We demonstrated, by patch clamp technique applied to A549 cells, that O3 exposure alters the Cl current-voltage relation, with the appearance of a large outward rectifier component. Experiments with activators/inhibitors of specific Cl-channels, showed ORCC (Outward Rectifier Chloride Channel) as the most involved channel. Being H2O2 one of the main mediators of O3 induced cellular damage, we verified if catalase (CAT) treatment prevented this effect. Indeed CAT was able to rescue OS induced Cl current alteration. Preliminary RT-PCR showed a decrease of Ano6 (integral part of ORCC) gene expression with H2O2 treatment and a recovery to control level with CAT pre-incubation. Since CAT is regulated by NRF2, we pre-treat the cells with the NRF2 activators, Resveratrol and tBHQ. Immunochemical and immunocytochemical results showed its significant activation in both cases. By the functional point of view these products were able to suppress the OS effect on Cl current. These data brings new insights on the mechanisms involved in OS induced lung tissue damage, pointing out the ability of the cell to modulate the membrane currents by the antioxidant response due to Resveratrol and tBHQ.