Saccharomyces Cerevisiae Var Boulardii CNCM I–1079 Reduces Expression of Genes Involved in Inflammatory Response in Porcine Cells Challenged by Enterotoxigenic E. Coli and Influences Bacterial Communities in an In Vitro Model of the Weaning Piglet Colon

International audienceEnterotoxigenic Escherichia coli (ETEC) is the main infectious agent responsible for pigletpost-weaning diarrhea with high mortality rates. Antimicrobials represent the current principal strategy for treating ETEC infections in pig farms, but the occurrence of multi-resistant bacterial strainshas considerably increased in the last decades. Thus, finding non-antibiotic alternatives becomes areal emergency. In this context, we investigated the effect of a live yeast strain, Saccharomyces cerevisiaevar boulardii CNCM I-1079 (SB) in an in vitro model of the weaning piglet colon implemented witha mucus phase (MPigut-IVM) inoculated with ETEC and coupled with an intestinal porcine cellline IPI-2I. We showed that SB was able to modulate the in vitro microbiota through an increasein Bacteroidiaceae and a decrease in Prevotellaceae families. Effluents collected from the SB treatedbioreactors were able to mitigate the expression level of genes encoding non-gel forming mucins, tightjunction proteins, innate immune pathway, and pro-inflammatory response in IPI-2I cells. Furthermore, SB exerted a significant protective effect against ETEC adhesion on porcine IPEC-J2 intestinalcells in a dose-dependent manner and showed a positive effect on ETEC-challenged IPEC-J2 bylowering expression of genes involved in pro-inflammatory immune responses. Our results showedthat the strain SB CNCM I-1079 could prevent microbiota dysbiosis associated with weaning andprotect porcine enterocytes from ETEC infections by reducing bacterial adhesion and modulating theinflammatory respons