Food-grade TiO2 is trapped by intestinal mucus in vitro but does not impair mucin O-glycosylation and short-chain fatty acid synthesis in vivo: implications for gut barrier protection

Pauline Talbot (1) , Joanna M. Radziwill-Bienkowska (2) , Jasper B.J. Kamphuis (3) , Karine Steenkeste (4) , Sarah Bettini (3) , Véronique Robert (1) , Marie-Louise Noordine (1) , Camille Mayeur (1) , Eric Gaultier (5) , Philippe Langella (1) , Catherine Robbe-Masselot (6) , Eric Houdeau (5) , Muriel Thomas (1) , Muriel Mercier-Bonin (7)

1 MICALIS - MICrobiologie de l'ALImentation au Service de la Santé
2 Institute of Biochemistry and Biophysics
3 ToxAlim - ToxAlim
4 ISMO - Institut des Sciences Moléculaires d'Orsay
5 ToxAlim-ENTeRisk - Endocrinologie & Toxicologie de la Barrière Intestinale
6 CNRS - Centre National de la Recherche Scientifique
7 ToxAlim-NGN - Neuro-Gastroentérologie & Nutrition

Titanium dioxide (TiO2) particles are commonly used as a food additive (E171 in the EU) for its whitening and opacifying properties. However, the risk of gut barrier disruption is an increasing concern because of the presence of a nano-sized fraction. Food-grade E171 may interact with mucus, a gut barrier protagonist still poorly explored in food nanotoxicology. To test this hypothesis, a comprehensive approach was performed to evaluate in vitro and in vivo interactions between TiO2 and intestinal mucus, by comparing food-grade E171 with NM-105 (Aeroxyde P25) OECD reference nanomaterial. We tested E171-trapping properties of mucus in vitro using HT29-MTX intestinal epithelial cells. Time-lapse confocal laser scanning microscopy was performed without labeling to avoid modification of the particle surface. Near-UV irradiation of E171 TiO2 particles at 364 nm resulted in fluorescence emission in the visible range, with a maximum at 510 nm. The penetration of E171 TiO2 into the mucoid area of HT29-MTX cells was visualized in situ. One hour after exposure, TiO2 particles accumulated inside "patchy" regions 20 mu m above the substratum. The structure of mucus produced by HT29-MTX cells was characterized by MUC5AC immunofluorescence staining. The mucus layer was thin and organized into regular "islands" located approximately 20 mu m above the substratum. The region-specific trapping of food-grade TiO2 particles was attributed to this mucus patchy structure. We compared TiO2-mediated effects in vivo in rats after acute or sub-chronic oral daily administration of food-grade E171 and NM-105 at relevant exposure levels for humans. Cecal short-chain fatty acid profiles and gut mucin O-glycosylation patterns remained unchanged, irrespective of treatment. Food-grade TiO2 is trapped by intestinal mucus in vitro but does not affect mucin O-glycosylation and short-chain fatty acid synthesis in vivo, suggesting the absence of a mucus barrier impairment under "healthy gut" conditions.

Mots clés: Food-grade TiO2; Gut barrier; Mucin O-glycans; Short-chain fatty acids; Mucus

Domaines: Biotechnologies

Pauline Talbot, Joanna M. Radziwill-Bienkowska, Jasper B.J. Kamphuis, Karine Steenkeste, Sarah Bettini, et al.. Food-grade TiO2 is trapped by intestinal mucus in vitro but does not impair mucin O-glycosylation and short-chain fatty acid synthesis in vivo: implications for gut barrier protection. Journal of Nanobiotechnology, 2018, 16 (1), pp.53. ⟨10.1186/s12951-018-0379-5⟩. ⟨hal-02624418⟩