Titanium dioxide E171 consumption exacerbates Listeria monocytogenes infection in mice

The food additive titanium dioxide is commonly utilized to enhance the appearance and flavor of food products. However, this substance has been linked to gastrointestinal disorders. The aim of this study was to investigate the impact of dietary exposure of titanium dioxide E171 on Listeria monocytogenes infection in mice. Mice were mainly divided into the control, LM group (L. monocytogenes infection), and E171+LM groups (E171 supplementation before L. monocytogenes infection). Pre-exposure to E171 resulted in increased bacterial counts in the liver, spleen, ileum, colon, mesenteric lymph nodes, and feces of mice after L. monocytogenes infection. Moreover, E171 exposure increased the levels of pro-inflammatory cytokines while attenuating the levels of anti-inflammatory cytokines in mice infected with L. monocytogenes. Meanwhile, mice in the E171+LM group exhibited considerably more severe colonic inflammation and worse intestinal barrier function than mice in the LM group. The 16S rRNA gene sequencing revealed a shift in the composition of the gut microbiota of mice in the E171+LM group, characterized by a decrease in the relative abundance of Firmicutes and a decrease in the Firmicutes-to-Bacteroidetes ratio. The levels of acetate, butyrate, and isobutyrate were markedly decreased within the cecum of mice in the E171+LM group in comparison to mice in the LM group. In conclusion, these results suggest that E171 exposure could exacerbate L. monocytogenes infection in mice, which may provide useful information for future risk assessment of this commonly used food additive.