4-HYDROXY-2-NONENAL-PROTEIN ADDUCTS AND APOPTOSIS IN MURINE LUNG-CELLS AFTER ACUTE OZONE EXPOSURE

Ozone is a photochemically generated pollutant that can cause acute pu lmonary inflammation and induce cellular injury and may contribute to the development or exacerbation of chronic lung diseases. Despite exte nsive investigation, the mechanisms of ozone and oxidant-induced cellu lar injury are still uncertain. Ozone has been reported to cause the f ormation of aldehydes in biological fluids that could explain many of the cellular effects caused by ozone. One of the most toxic aldehydes formed during oxidant-induced lipid peroxidation is 4-hydroxy-2-nonena l (HNE). HNE reacts primarily with Cys and secondarily with Lys and Hi s amino acids, altering protein function and forming protein adducts t hat can be detected using specific adducts. In this study, we investig ated whether ozone could cause the formation of HNE by assaying for HN E-protein adducts in cells isolated by lung lavage from C3H/HeJ mice e xposed to 2.0 and 0.25 ppm ozone for 3 hr. Since oxidative stress and HNE have been shown to cause apoptosis are also examined the lung lava ge cells for evidence of apoptosis following ozone exposure, Using a s pecific polyclonal antibody against HNE-amino acid adducts, two princi ple HNE-protein adducts were detected by Western analysis in cells obt ained after ozone exposure at approximately 86-90 and 32 kDa. In addit ion to cell necrosis, apoptosis of lung cells was significant 3 hr aft er ozone exposure as detected using a Cell Death ELISA procedure and c onfirmed with DNA ladder and morphological analysis. The apoptotic cel l injury peaked at 6 hr postexposure and decreased by 24 hr. Taken tog ether, these results demonstrate that HNE is formed in vivo following ozone exposure and HNE appears to form specific protein adducts in lun g cells. Furthermore, ozone can cause lung cell injury by an apoptotic mechanism in addition to a necrotic mechanism, Since HNE is toxic to cells and is formed as a result of ozone exposure, it may contribute t o the lung cell injury following, ozone exposure. (C) 1996 Academic Pr ess, Inc.