Functional effects of carbon nanotubes on airway epithelial cells

Carbon nanotubes (CNTs) are a group of widely produced nanomaterials, the potential biological effects of which have aroused occupational and environmental concerns. We hypothesized epithelial cell exposure to unpurified, as manufactured CNT (single walled nanotubes and multi walled nanotubes) may alter their barrier function. The effect of CNT exposure was studied in air‐interface cultured Calu‐3 cells in log unit concentrations over 7 orders of magnitude (4 μg/cm 2 ‐ 4 pg/cm 2 ). Transepithelial ion transport and the barrier function expressed as transepithelial electrical resistance (TEER) were studied using electrophysiology. 24 or 48 h exposure to both types of nanotubes decreased TEER and depressed epinephrine‐stimulated Cl − secretion. The most pronounced effects on both TEER and epinephrine stimulated ion secretion were manifested at and above 4 ng/cm 2 . The cAMP levels for the exposed vs control cells were not different suggesting an effect manifested after the epinephrine‐induced increase in cAMP. These results suggest that nanotube exposures at very low levels have adverse effects on barrier epithelial cell permeability (TEER) and the secretion of ions (and compensatory water movement) in airway epithelia. To our knowledge, this is the first demonstration of effects on physiological function at very low nanotube concentrations that mimic potential in vivo exposures. Funding: NIGMS RO1GM085218.