N-acetylcysteine prevents cytotoxic effects induced by man-made mineral fibers in a human bronchial epithelial cell line

Man-made mineral fibres (MMMFs) such as glass wool (GW), rock wool (RW) and refractory ceramic fibres (RCFs) are widely used as substitutes of asbestos. The present study aimed to investigate the cytotoxic effects on human bronchial epithelial cells (BEAS-2B) exposed to GW1, RW1 and RCF2, considering their properties similar to that of asbestos. We assessed cell viability; cell morphological changes; apoptotic rate; DNA damage; reactive oxygen species (ROS) generation; activities of caspase-3, caspase-8 and caspase-9; and expression levels of FasL, phosphorylated p38, and total p38 MAPK proteins. N-acetyl-l-cysteine (NAC) was used as an ROS scavenger. We observed that MMMFs, especially RCF2, evidently changed cellular morphology, promoted DNA damage, and induced apoptosis. In addition, the cytotoxicities of MMMFs were dependent on ROS generation, and NAC could decrease their toxicity. Furthermore, our results showed that apoptosis induced by MMMFs was mediated by the mitochondrial apoptotic pathway and Fas death receptor pathway. Moreover, the p38 MAPK signalling pathway was also involved in the cytotoxicities of MMMFs. NAC exerts a protective effect against apoptosis and DNA damage induced by GW1, RW1 and RCF2. This study provides important implications for understanding the potential toxic effects of GW1, RW1 and RCF2 exposure; it also indicates that NAC may prevent respiratory diseases induced by exposure to MMMFs.