The ability of oxidative stress to mimic quartz-induced chemokine responses is lung cell line-dependent

Oxidative stress induced by surface-generated radicals has been a dominating hypothesis to explain how mineral particles and fibers trigger cellular responses. However, conflicting studies suggest that the importance of particle-derived formation of reactive oxygen species (ROS) requires further examination. The present study focuses on whether oxidative stress in the form of H2O2-exposure may mimic the effects of quartz particles on chemokine responses in epithelial lung cells. The results show that H2O2 and quartz exposure induced almost identical levels of CXCL8 (interleukin-8) release in the alveolar epithelial cell line A549, but in the bronchial epithelial cell line BEAS-2B, H2O2-exposure did not affect CXCL8 release significantly, whereas quartz induced a 16-fold increase. Among 17 different cytokine and chemokine genes H2O2 induced up-regulation of only IL-5 in BEAS-2B cells, while quartz increased the expression of 8 different cytokines and chemokines. In A549 cells, however, there was a moderate but significant correlation between the cytokine/chemokine gene-expression profiles induced by the two agents. Thus, the response to oxidative stress may vary considerably between different lung cell lines. Moreover, the results from the BEAS-2B cells strengthen the notion that non-oxidant initiation mechanisms may also be important to the effects of mineral particles and fibers.