Pulmotoxicological effects caused by long-term titanium dioxide nanoparticles exposure in mice

► Exposure to TiO2 NPs could be significantly accumulated in the lung. ► Exposure to TiO2 NPs caused pulmonary injury in mice. ► Exposure to TiO2 NP promoted the expression of inflammatory cytokines in the lung. ► Exposure to TiO2 NP caused ROS overproduction in the lung. Exposure to titanium dioxide nanoparticles (TiO2 NPs) has been demonstrated to result in pulmonary inflammation in animals; however, very little is known about the molecular mechanisms of pulmonary injury due to TiO2 NPs exposure. The aim of this study was to evaluate the oxidative stress and molecular mechanism associated with pulmonary inflammation in chronic lung toxicity caused by the intratracheal instillation of TiO2 NPs for 90 consecutive days in mice. Our findings suggest that TiO2 NPs are significantly accumulated in the lung, leading to an obvious increase in lung indices, inflammation and bleeding in the lung. Exposure to TiO2 NPs significantly increased the accumulation of reactive oxygen species and the level of lipid peroxidation, and decreased antioxidant capacity in the lung. Furthermore, TiO2 NPs exposure activated nuclear factor-κB, increased the levels of tumor necrosis factor-α, cyclooxygenase-2, heme oxygenase-1, interleukin-2, interleukin-4, interleukin-6, interleukin-8, interleukin-10, interleukin-18, interleukin-1β, and CYP1A1 expression. However, TiO2 NPs exposure decreased NF-κB-inhibiting factor and heat shock protein 70 expression. Our results suggest that the generation of pulmonary inflammation caused by TiO2 NPs in mice is closely related to oxidative stress and the expression of inflammatory cytokines.