Fig 8. Effects on the airway epithelial cell barrier formed by Calu-3 cells.

Evaluation of TEER during the exposure to TiO2 NM-103 (A) and NM-104 (B), ZnO NM-110 (C) and NM-111 (D) and SiO2 NM-200 (E) and NM-203 (F). Calu-3 epithelial cells were grown for 10 days in a double-chamber culture system to form a tight monolayer. The epithelial monolayer was then exposed at the apical side to different concentrations of NMs: 128 μg/ml (80 μg/cm²) of TiO2 and SiO2, 32 μg/ml (20 μg/cm²) and 64 μg/ml (40 μg/cm²) of ZnO. The trans-epithelial electrical resistance (TEER) was measured at the indicated times with a voltohmeter. Data are values obtained from 12 monolayers used in three separate experiments and are expressed as % of the initial value ± SD (see Methods). Statistical analysis was performed using two-way ANOVA followed by Bonferroni post-hoc test. **p< 0.01, ***p< 0.001.