Fig. 2.

Titanium dioxide nanoparticles (TiO₂-NP) induce disassembly of epithelial tight junctions. 16HBE cells were exposed to 10–100 μg/mL TiO₂. Cells were immunofluorescently labeled for TiO₂-NP apical junctional complex (AJC) proteins zonula occludens-1 (ZO-1), occludin, β-catenin, and E-cadherin (A). Arrows indicate areas of disruption. Permeability of the barrier was examined by transepithelial electrical resistance (TEER) at 48 h reading after exposure to TiO₂-NP, and changes were normalized to the time zero for each group (B). Human primary epithelial cells were exposed to 10–100 μg/mL TiO₂. Cells were immunofluorescently labeled for AJC proteins ZO-1, E-cadherin, β-catenin, and occludin (C). Permeability of the barrier was examined by TEER 96 h after exposure to TiO₂-NP, and changes were normalized to the time zero for each group (D). Scale bar = 20 μm. Data are presented as means ± SE; n ≥ 3, *P < 0.05, **P < 0.01.