Effect of ozone oxidative stress on chloride current in human lung cells: Chemical mediators and protective role of catalase

In this work we have investigated the effects of ozone (O3), one of the most noxious pollutants to which respiratory tract is organ most exposed, on Cl currents in human cultured lung epithelial cells (A549 line). Biological and electrophysiological technique was applied to study the action of O3 and its main bio-products (4HNE and H2O2) on Cl currents in A549 cells, which simulates the first barrier encountered by oxidants. O3 exposure (0.1 ppm, 30’) significantly affects Cl current inducing a large outward rectifier component. While 4HNE (up to 25 mM) was not able to reproduce the effect, H2O2 produced by the cell (Glucose Oxidase 10mU) mimicked O3 damage. Then we analyzed the effect of G.O. treatment on ORCC gene expression, the two Cl channels mainly involved in current alteration. RT-PCR showed the ability of oxidative stress due to H2O2 to modulate the gene expression of these channels. Eventually, we verified the protective effect of catalase (1 mM, 1.30 h). The results showed the ability of catalase in suppressing the outward rectifier component activated by O3, bringing back the current values to the control level. This study brings new insights on the mechanisms involved in O3 induced lung tissue damage, confirming its ability to modify the cellular redox homeostasis, and to highlight a new aspect such as the alteration of Cl channel functionality via H2O2 formation.