Absolute quantitative lipidomics reveals the disturbance of lipid metabolism induced by oral exposure of titanium dioxide nanoparticles

Abstract

The widespread use of titanium dioxide nanoparticles (TiO₂ NPs) as a white pigment in consumer goods increases the possibility of its release into the environment, which poses a great health risk to human beings. Many studies have proved the liver damage caused by TiO₂ NPs, but the research about the potential effects of TiO₂ NPs on liver lipid metabolism has been limited. Therefore, we selected Sprague-Dawley (SD) rats to explore the effects of long-term exposure to TiO₂ NPs on lipid metabolism. Rats were exposed to TiO₂ NPs at 0, 2, 10, 50 mg/kg body weight daily for 90 consecutive days. Subsequently, absolute quantitative lipidomics was used to ascertain variation of differential lipid metabolites in rat liver and serum. The results showed that TiO₂ NPs (50 mg/kg) changed 22 lipid metabolites such as DAG (18:2/20:5) and TAG (58:10/FA18:2) in rat liver. In the serum, the alteration of 119 lipid metabolites such as DAG (18:0/18:2) were more significant. There was a significant correlation between the different lipid metabolites in liver and serum. At the same time, it was observed that the relative expression levels of oxidative stress-related genes Nrf-2 and Ho-1 changed significantly, and they were closely related to differential metabolites. In conclusion, oral exposure of TiO₂ NPs has changed the lipid metabolomics of liver and serum, and the strong induction of oxidative stress may be related to it. TAG and DAG are key metabolites and metabolic pathways in two distinct biological samples, serving as potential indicators of liver injury to a certain extent.