Impact of tannins in presence or absence of saliva on the mucus layer of intestinal cells.

OBJECTIVE

Dietary tannins may interact with host proteins such as mucins of the oral cavity, other salivary proteins or digestive enzymes, but less is known about their interaction with intestinal mucins. The purpose of this study was to document the impact that digested apple tannins, in absence or presence of saliva, have on the intestinal mucus layer.

DESIGN

The study was performed using a mucin-secreting mixed culture Caco-2/HT29-MTX. Mucins were revealed through staining of GlcNAc and sialic acid using WGA-Alexa488 after exposure to the digestive medium, digested polyphenols or digested polyphenols in presence of pooled human saliva. Three-dimensional characterization of the mucus layer was performed by confocal microscopy coupled to machine learning-based image analysis.

RESULTS

Overall, digested tannins increased the height of the pseudo villi observed on the cell culture. Tannins alone also reduced significantly the proportion of the dense adherent mucus on cells, and this effect was not retained when tannins had been mixed with saliva prior to digestion.

CONCLUSIONS

The results suggest that interaction of polyphenols with saliva may have digestive consequences as far as in the intestine.