[Pyroptosis induced by zinc oxide nanoparticles in A549 cells].

OBJECTIVE: To explore whether exposure to zinc oxide nanoparticles (ZnO-NPs) induced pyroptosis in human alveolar type II epithelial cells (A549). METHODS: A549 cells were stimulated with different concentrations of ZnO-NPs (10 and 20 microg/ml) for 8 and 24h, respectively. The activity of lactic dehydrogenase (LDH) and the levels of interleukin-1beta (IL-1beta) in cell culture media were respectively measured by LDH activity kit and human IL-1beta ELISA kit. The activity of caspase-1 in A549 cells was detected by caspase-1 colorimetric assay kit. RESULTS: At 8h exposure to ZnO-NPs, there was no significant difference in the activity of LDH in the cell culture media among the ZnO-NPs-treated and control groups, but the activity of caspase-1 and the levels of IL-1beta in A549 cells were significantly increased in 20 microg/ml ZnO-NPs group compared to that in the control group (P < 0.05). Levels of IL-1beta and activity of LDH in the groups treated with ZnO-NPs (10 or 20 microg/ml) were significantly higher than that in the control group after 24 h exposure to ZnO-NPs, but there was no significant difference in the activity of caspase-1 among ZnO-NPs and control group. CONCLUSION: ZnO-NPs (20 microg/ml) treatment induces early increase in caspase-1 activity followed by the increase in LDH activity and IL-1 levels, indicative of pyroptosis in A549 cells.