Titanium dioxide nanoparticles impair lung mitochondrial function

Titanium dioxide nanoparticles (TiO2 NPs) are used in an increasing number of human products such as cosmetics, sunscreen, toothpaste and paints. However, there is clear evidence about effects associated to TiO2 NPs exposure, which include lung inflammation and tumor formation and these effects are related to reactive oxygen species (ROS) formation. The ROS generation could be attributed to a mitochondrial dysfunction. Even though, it has been shown that TiO2 NPs exposure can induce some alterations in mitochondria including cytochrome c release to cytosol, change in mitochondrial permeability and decrease of mitochondrial membrane potential (ΔΨm), there is no information about the changes in mitochondrial function induced by TiO2 NPs. We hypothesized that TiO2 NPs effects are associated with mitochondrial dysfunction and redox unbalance. To test our hypothesis we isolated mitochondria from lung tissue of rats and exposed them to 10 (g TiO2 NPs (particle size < 25 nm)/mg protein for 1 h. Our results showed that TiO2 NPs decreases NADH levels and impairs ΔΨm and mitochondrial function accompanied by ROS generation during mitochondrial respiration.