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 Ω cm2 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.