Nanosized TiO₂ is internalized by dorsal root ganglion cells and causes damage via apoptosis

Titanium dioxide (TiO₂) is widely used as ingredient in several products in the nanoform. TiO₂-nanoparticles (NPs) are also currently studied for different medical applications. A large debate exists on possible adverse health effects related to their exposure. While there is some evidence of TiO₂-NP central nervous system toxicity, their effects on peripheral neurons have been poorly explored. In this study we investigated the effects of TiO₂-NPs on dorsal root ganglion (DRG) sensory neurons and satellite glial cells that may be reached by nanoparticles from the bloodstream. We found that TiO₂-NPs are internalized in DRG cells and induce apoptosis in a dose dependent manner in both types of cells, ROS production and changes in expression of proinflammatory cytokine IL-1β. Furthermore, we found that the axonal retrograde transport is altered in neurons upon exposure to TiO₂-NPs. Overall, the results indicate a potential neurotoxic effect of TiO₂-NPs on DRG cells. From the Clinical Editor: Exposure to titanium dioxide nanoparticles is increasing in medical practice. Little is known about their potential toxic effects on the peripheral nervous system. The authors studied this aspect and showed that titanium nanoparticles might potentially cause toxicity over long term.