Crystalline silica Min-U-Sil 5 induces oxidative stress in human bronchial epithelial cells BEAS-2B by reducing the efficiency of antiglycation and antioxidant enzymatic defenses

Reactive oxygen species (ROS) play an important role as mediators of pulmonary damage in mineral dust-induced diseases. Studies carried out to date have largely focused on silica-induced production of ROS by lung phagocytes. In this study we investigated the hypothesis that crystalline silica Min-U-Sil 5 can induce elevations in intracellular ROS in human bronchial epithelial cells BEAS-2B, via an indirect mechanism that involves ROS-inducing intracellular factors, through a reduction of antiglycation (glyoxalase enzymes) and antioxidant (paraoxonase 1 and glutathione-S-transferases) enzymatic defenses. The results show that crystalline silica Min-U-Sil 5 causes a significant reduction in the efficiency of antiglycation and antioxidant enzymatic defenses, paralleled by an early and extensive ROS generation, thus preventing the cells from an efficient scavenging action, and eliciting oxidative damage. These results confirm the importance of ROS in development of crystalline silica-induced oxidative stress and emphasize the pivotal role of antiglycation/antioxidant and detoxifying systems in determining the level of protection from free radicals-induced injury for cells exposed to crystalline silica Min-U-Sil 5.