GOS/FOS supplementation in suckling rats improves rv diarrhoea by changing the intestinal expression of toll-like receptors and the microbiota composition

Introduction: The addition of a mixture of short-chain galacto-oligosaccharides (scGOS) and long-chain fructo-oligosaccharides (lcFOS) at a 9:1 ratio in infant formulas has demonstrated multiple health-promoting effects, including the modulation of the immune response, microbiota composition and infections. We have previously reported that scGOS/lcFOS ameliorates RV diarrhoea, but little is known about its mechanism of action. Objectives: To investigate whether the amelioration of RV diarrhoea observed after the supplementation with scGOS/lcFOS was linked to changes in the intestinal innate receptors and microbiota composition. Methods: Lewis rats were daily administered either scGOS/ lcFOS or a vehicle from days 2-8 of life. On day 5, RV was administered intragastrically. The RV group received only the infection and the REF group the vehicle. Faecal samples were collected daily for the clinical evaluation. On day 8, the animals were sacrificed to obtain the small intestine and assess the Toll-like receptor (TLR) expression by real-time PCR. The faecal microbiota composition was studied by Illumina sequencing of V3-V4 16S rRNA. Results: The RV induced moderate diarrhoea with an increase in TLR2 expression and affected gut microbiota composition, which was characterized by loss of bacterial groups, such as Streptococcus and Staphylococcus, and colonization by many bacteria from the Proteobacteria phylum. The supplementation with the mixture of oligosaccharides ameliorated the RV diarrhoea in terms of severity, incidence and duration and enhanced gene expression of TLR5 and TLR9. Finally, the changes in the microbiota composition due to the challenge by RV were prevented by the supplementation with scGOS/lcFOS. Conclusions: These results evidence that supplementation with scGOS/lcFOS ameliorates the diarrhoea induced by RV, an effect that could be mediated by the prevention of changes in the microbiota composition and the crosstalk between the microbiota and immune system. Conflict of interest: ST, KK and JG declare that they are employees of Danone Nutricia Research.