Combined effects of TiO₂ nanoparticle and fipronil co-exposure on microbiota in mouse intestine

Oral exposure to nanoparticles (NPs) may affect intestinal microbiota, and this effect may be further changed by co-contaminates. In the present study, we investigated the combined effects of TiO₂ NPs and fipronil (FPN) on microbiota in mouse intestines. Mice were intragastric exposed to 5.74 mg/kg TiO₂ NPs, 2.5 mg/kg FPN, or both of them, once a day, for 30 days. The results showed that individual exposure to TiO₂ NPs or FPN decreased body weight and induced pathological changes in intestines. The exposure was also associated with increased cleaved caspase-3 protein, oxidative stress and decreased tight junction protein expression. Furthermore, the levels of diamine oxidase (DAO), lipopolysaccharide (LPS) and inflammatory cytokines in serum were also elevated, indicating increased intestinal barrier permeability. As expected, both TiO₂ NPs and FPN decreased the diversity and altered the composition of microbiota. However, the observed effects were not further enhanced after the co-exposure to TiO₂ NPs and FPN, except that Romboutsia was only significantly increased after the co-exposure to TiO₂ NPs + FPN. We concluded that oral exposure to TiO₂ NPs and FPN showed minimal synergistic effects on microbiota in mouse intestine.