Figure 4: Transepithelial electric resistance (TEER) values of the ABB coculture of NCI-H441 (treated at day 3 with Dexamethasone 1 μM) and HPMEC-ST1.6R. The ABB has been apically treated with PM10 (Figure 4(a)) and metal oxide NPs (Figure 4(b)). TEER values are expressed as Ωcm2 and show no significant differences between control and PM10 and TiO2-treated cells. Cells treated with CuO NPs showed a significant reduction in TEER values. ↑ indicates the day of apical treatment with particles. Gelatine-coated inserts without cells were used as blanks. Data are expressed as means ± SE of 3 different experiments. *Statistically different from control , ANOVA.