Features of changes in oxidant/antioxidant system of alveolar macrophages exposed to cigarette smoke

Abstract

Oxidants and reactive oxygen species (ROS), contained in cigarette smoke (CD), can initiate oxidative stress, which results from oxidant/antioxidant imbalance. The aim of this study was to investigate the influence of cigarette smoke extract (CSE) on ROS production, lipid peroxidation (LPO) level and antioxidant enzymes activity in alveolar macrophages (AM) depending on the tar concentration in CSE and the duration of its affection. AM were isolated from bronchoalveolar lavage fluid of rats and incubated for 1 h and 24 h in a medium with the addition of varying concentrations of CSE - 0,7 g/L, 1,4 g/L and 2,1 g/L. The activity of free radical processes was evaluated on the basis of the determination of hydrogen peroxide (H202) concentration and also the concentration of LPO products reacting with thiobarbituric acid (TBA). The status of the enzymatic antioxidant system of AM was assessed by the level of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities. H202 concentration, TBA-active LPO products level and also SOD, CAT and GPx enzyme activities were determined spectrophotometrically. It is found out that with the joint incubation of AM and CSE for 1 h the increase in H202 concentration in cells and in incubation medium occurs due to the increase in its production in AM 2 times, while during incubation for 24 h - 3,4 times. Another reason for the increasing in H202 concentration in AM is the reduction of the activity of the enzymes (CAT and GPx), which carry out the process of H202 decomposition. SOD activity in AM decreases already after the incubation for 1 h in a medium enriched by tar of a tobacco smoke under the concentration of 0,7 g/L by 16%, 1,4 g/L - 24%, 2,1 g/L - 30%. Even more pronounced suppression of SOD activity occurred during incubation for 24 h, which with the increasing tar concentration in CSE-medium was 70%, 80% and 86%, respectively. CSE has also provided the marked inhibitory effect on CAT activity. After the incubation for 1 h CAT activity was significantly reduced compared with control values (by 22%, 51% and 71%, respectively). After the incubation for 24 h CAT activity under the influence of CSE was reduced to zero. The level of GPx activity was reduced after the incubation for 1 h under the tar concentration of 0,7 g/L by 22%, 1,4 g/L - 39% and 2,1 g/L - 64% (p<0.05). After the incubation for 24 h the average inhibition of GPx activity regardless of the tar concentration in CSE medium was 65%. TBA-active LPO products contents in AM increased 2 times during incubation of cells with CSE for 1 h (3,10 nmol/10(6) cells vs 1,54 nmol/10(6) cells, respectively, p<0.05) and 2,7 times during incubation for 24 h (4,25 nmol/10(6) cells vs 1,92 nmol/10(6) cells, respectively, p<0,05). The present findings indicate that cigarette smoke causes the increase in ROS production accompanied by the decrease in the activity of key enzymes of antioxidant protection.