Impact of a live yeast strain: Saccharomyces boulardii CNCM I-1079 on intestinal gene expression of piglets at weaning

Saccharomyces cerevisiae boulardii is a probiotic yeast with an established history of use for the prevention and/or treatment of diarrhoea and chronic inflammatory disease in human medicine. More recently, S. boulardii has also been used in the pig industry to increase performance and reduce pathogen burden during vulnerable early life stages such as post-farrowing and weaning. Recent advances in DNA sequencing technology are now able to understand the host response to stress and nutritional intervention: it was the objective of this study.

In a blinded randomised controlled trial, we investigated the effect of a S. cerevisiae boulardii (SCB) strain (CNCM I-1079) on intestinal gene expression in piglets through the weaning transition.Oral supplementation of piglets with SCB (3.3 x 109 CFU/day) started at 7 d of age and continued daily until 35 d. At 21 d of age, piglets were randomly selected to be weaned and mixed with non-littermates or to remain suckling with their dam. Control piglets were subject to the same procedure without SCB. Gene expression analysis at 1, 4 and 14 days post-weaning were performed by qRT-PCR focusing on innate immune genes, and Illumina sequencing was performed on colonic tissue.

Gene expression network and pathway analysis - key targets for the understanding of weaning disorders and the mode of action of SCB - highlighted that weaning in non-supplemented piglets affected the expression of more than 1000 genes in the colon. Genes with the highest fold change were associated with proteolytic degradation of connective tissue, inflammatory responses and epithelium defence against bacterial and viral invasion. In contrast, the number of genes affected by weaning in SCB piglets was reduced by 60% compared to control animals, with the highest fold change genes related to metabolism and transport but none to activation of proteolytic damages, suggesting a possible protective role of SCB on gut barrier function at weaning. Evidence of immunoregulation by SCB in the small intestine, towards an anti-inflammatory profile was associated with the upregulation of Toll-like receptors and Interleukin-10 mRNA levels.

The transcriptomic approach allowed us to generate hypothesis on the mode of action of S. cerevisiae boulardii in the gut during the weaning transition. Our results suggest that weaning is a period of intense stress that profoundly affects gene expression in the gut and that SCB may alleviate the consequences of weaning by promoting regulatory immune responses and maintaining gut barrier integrity. Mechanism underlying these modes of action are under investigation.

Disclosure of Interest: None Declared.