Beryllium-stimulated reactive oxygen species and macrophage apoptosis

• Published in: Free radical biology & medicine 2005-04, Vol.38 (7), p.928-937
• Main Authors: Sawyer, Richard T., Dobis, David R., Goldstein, Mark, Velsor, Leonard, Maier, Lisa A., Fontenot, Andrew P., Silveira, Lori, Newman, Lee S., Day, Brian J.
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis; Beryllium - pharmacology; Caspase 8; Caspases - metabolism; Free Radical Scavengers - pharmacology; Free radicals; Inflammation; Macrophage; Macrophages - drug effects; Macrophages - metabolism; Metalloporphyrins - pharmacology; Mice; Reactive oxygen species; Reactive Oxygen Species - metabolism
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2004.12.014

Beryllium (Be), the etiologic agent of chronic beryllium disease, is a toxic metal that induces apoptosis in human alveolar macrophages. We tested the hypothesis that Be stimulates the formation of reactive oxygen species (ROS) which plays a role in Be-induced macrophage apoptosis. Mouse macrophages were exposed to 100 μM BeSO 4 in the absence and presence of the catalytic antioxidant MnTBAP (100 μM). Apoptosis was measured as the percentage of TUNEL + and caspase-8 + cells. ROS production was measured by flow cytometry using the fluorescence probes, dihydroethidine (DHE) and dichlorofluorescein diacetate (DCFH-DA). Be-exposed macrophages had increased TUNEL + cells (15 ± 1% versus controls 1 ± 0.2%, P < 0.05) and increased caspase-8 + cells (18.7 ± 2% versus controls 1.8 ± 0.4%, P < 0.05). Be-induced caspase-8 activation, and a 4-fold increase in ROS formation, was ameliorated by exposure to MnTBAP. Hydrogen peroxide (30 μM) exposure potentiated Be-induced caspase-8 activation, and was also attenuated by MnTBAP. Our data are the first to demonstrate that Be stimulates macrophage ROS formation which plays an important role in Be-induced macrophage apoptosis.