Toxic effects of the food additives titanium dioxide and silica on the murine intestinal tract: Mechanisms related to intestinal barrier dysfunction involved by gut microbiota

[Display omitted] •Food grade TiO2 micro-/nanoparticles and SiO2 nanoparticles can cause toxic effects to the murine intestine.•All three particles caused inflammatory damage to the intestine.•The particles altered the gut microbiota, especially mucus-associated bacteria.•Disruption of the intestinal mucus barrier and increased LPS production are key mechanisms.•Nano-TiO2 activated the intestinal PKC/TLR4/NF-κB signalling pathway. This study aimed to compare the effects of three food-grade particles (micro-TiO2, nano-TiO2, and nano-SiO2) on the murine intestinal tract and to investigate their potential mechanisms of action. A 28-day oral exposure murine model was established. Samples of blood, intestinal tissues and colon contents were collected for detection. The results showed that all three particles could cause inflammatory damage to the intestine, with nano-TiO2 showing the strongest effects. Exposure also led to changes in gut microbiota, especially mucus-associated bacteria. Our results suggest that the toxic effects on the intestine were due to reduced intestinal mucus barrier function and an increase in metabolite lipopolysaccharides which activated the expression of inflammatory factors downstream. In mice exposed to nano-TiO2, the intestinal PKC/TLR4/NF-κB signalling pathway was activated. These findings will raise awareness of toxicities associated with the use of food-grade TiO2 and SiO2.