Saccharomyces boulardii inhibits inflammatory bowel disease by trapping T cells in mesenteric lymph nodes

Background & Aims: Saccharomyces boulardii is a nonpathogenic yeast used for treatment of diarrhea. We used a mice model of inflammatory bowel disease (IBD) to analyze the effects of S boulardii on inflammation. Methods: Lymphocyte-transferred SCID mice, displaying IBD, were fed daily with S boulardii. Weight loss and inflammatory status of the colon were monitored. Nuclear factor-kappa B activity was assessed in the colon. The CD4(+) T-cell production of interferon (IFN) gamma was evaluated by enzyme-linked immunosorbent assay, and a comprehensive reverse- transcription polymerase chain reaction (RT-PCR) analysis for both colon and mesenteric lymph nodes was performed. Finally, we analyzed cell migration mechanisms in vitro and in vivo. Results: S boulardii treatment inhibits IBD. S boulardii induces an accumulation of IFN-gamma-producing T-helper I cells within the mesenteric lymph nodes correlated with a diminution of CD4(+) T-cell number and IFN-gamma production by CD4+ T cells within the colon. The influence of S boulardii treatment on cell accumulation in mesenteric lymph nodes was also observed in normal BALB/c mice and involves modifications of lymph node endothelial cell adhesiveness by a yeast secretion product. Conclusions: S boulardii has a unique action on inflammation by a specific alteration of the migratory behavior of T cells, which accumulate in mesenteric lymph nodes. Therefore, S boulardii treatment limits the infiltration of T-helper I cells in the inflammed colon and the amplification of inflammation induced by proinflammatory cytokines production. These results suggest that S boulardii administration may have a beneficial effect in the treatment of IBD.