Objective To examine the effect of nuclear factor E2-related factor 2 (Nrf-2) on silica nanoparticle (nano-SiO2)-induced oxidative damage to human bronchial epithelial cells.
Methods Human bronchial epithelial cells (16HBE) were exposed to 1.0, 2.5, 5.0, 10.0, 25.0, and 50.0 μg/mL nano-SiO2 for 24 h to determine cell viability. According to the results of cell viability assay, the cells in the following tests were then exposed to 2.5, 5.0, and 10.0 μg/mL nano-SiO2 (low, medium, and high dose groups, respectively), and the tests included cellular reactive oxygen species (ROS), malondialdehyde (MDA), total superoxide dismutase (T-SOD), and glutathione peroxidase (GSH-Px). Western Blotting was used to estimate the expression levels of Nrf-2 in total and nuclear proteins, and real-time quantitative polymerase chain reaction was used to assess the mRNA expression level of Nrf-2.
Results The cellular ROS level significantly increased (P<0.01), while T-SOD and GSH-Px levels decreased (P<0.05) in the medium and the high dose groups. The MDA contents significantly increased in the low, medium, and high dose groups (P<0.05). The total Nrf-2 protein and the Nrf-2 mRNA expression levels increased in the low dose group, while decreased in the medium and the high dose groups; and the nuclear Nrf-2 protein expression level significantly increased in the low, medium, and high dose groups.
Conclusion In the current study settings, nano-SiO2 with 15 nm in size can induce oxidative damage in human bronchial epithelial cells, and Nrf-2 activation and nuclear translocation play important roles in the regulation of intracellular oxidative-antioxidative system.
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