University of Massachusetts, Amherst,
Keywords: nanoparticles, food safety, titanium dioxide
Summary:Titanium dioxide (TiO2), a commonly used food additive, contains an appreciable fraction of particles in nano-scale. There is increasing concern about the potential health risks associated with foodborne TiO2 nanoparticles (NPs), especially within certain susceptible populations, such as the obese. This study aimed to determine the potential adverse effects of TiO2 NPs in obese individuals and the potential role of gut microbiota in mediating the adverse effects. Two types of TiO2 (30 nm and E171-Food grade TiO2, 0.1% wt%) were fed to two populations of mice (high-fat diet-fed obese mice and low-fat diet-fed non-obese mice). Meanwhile, fecal samples from the above groups were collected for orally transplanting to mice fed a low-fat diet for 10 weeks. Histological analysis, immunohistochemistry, 16s rRNA gene amplicon sequencing and short-chain fatty acid (SCFA) analysis were utilized to characterize inflammation status, the composition of the microbiota and the effects of altered gut microbiota on the inflammation status of mouse colon. The results showed that dietary TiO2 NPs led to a significant dysbiosis of gut microbiota with stronger alterations in the high-fat diet-fed obese mice than the low-fat diet-fed non-obese mice. The abundance of inflammation-related cytokines (e.g., IL-10, IL-12p70, and IL-17) and myeloperoxidase (MPO) in colonic mucosa were significantly altered by TiO2 NPs to produce an inflammatory state. TiO2 NPs decreased the cecal levels of SCFAs such as butyrate. After 10 weeks of microbial transplant, microbiota from the obese mice consuming a high-fat diet with TiO2 NPs led to an increase of pro-inflammatory cytokines and loss of healthy colonic morphology in the colon of the low-fat diet-fed recipient mice, indicating a significant colonic inflammation. Overall, these findings provided a valuable new perspective on the potential adverse effects and underlying mechanisms of foodborne TiO2 NPs among obese vs. non-obese populations.