Immunocompetent cell targeting by food-additive titanium dioxide
- John W. Wills
- Alicja Dabrowska
- Jack Robertson
- Michelle Miniter
- Sebastian Riedle
- Huw D. Summers
- Rachel E. Hewitt
- Adeeba Fathima
- Alessandra Barreto da Silva
- Carlos A. P. Bastos
- Stuart Micklethwaite
- Åsa V. Keita
- Johan D. Söderholm
- Nicole C. Roy
- Don Otter
- Ravin Jugdaohsingh
- Pietro Mastroeni
- Andy P. Brown
- Paul Rees
- Jonathan J. Powell
2025-07-04
Food-grade titanium dioxide (fgTiO 2 ) is a bio-persistent particle under intense regulatory scrutiny. Yet paradoxically, the only known cell reservoirs for fgTiO 2 are graveyard intestinal pigment cells which are metabolically and immunologically quiescent. Here we identify immunocompetent cell targets of fgTiO 2 in humans, most notably in the subepithelial dome region of intestinal Peyer’s patches. Using multimodal microscopies with single-particle detection and per-cell / vesicle image analysis we achieve correlative dosimetry, quantitatively recapitulating human cellular exposures in the ileum of mice fed a fgTiO 2 -containing diet. Epithelial microfold cells selectively funnel fgTiO 2 into LysoMac and LysoDC cells with ensuing accumulation. Notwithstanding, proximity extension analyses for 92 protein targets reveal no measureable perturbation of cell signalling pathways. When chased with oral ΔaroA - Salmonella , pro-inflammatory signalling is confirmed, but no augmentation by fgTiO 2 is revealed despite marked same-cell loading. Interestingly, Salmonella causes the fgTiO 2 -recipient cells to migrate within the patch and, sporadically, to be identified in the lamina propria, thereby fully recreating the intestinal tissue distribution of fgTiO 2 in humans. Immunocompetent cells that accumulate fgTiO 2 in vivo are now identified and we demonstrate a mouse model that finally enables human-relevant risk assessments of ingested, bio-persistent (nano)particles.