Probiotic yeasts: anti-inflammatory potential of various non-pathogenic strains in experimental colitis in mice.

Aim: To evaluate the in vitro immunomodulation capacity of various non-pathogenic yeast strains and to investigate the ability of some of these food grade yeasts to prevent experimental colitis in mice.

Methods: In vitro immunomodulation was assessed by measuring cytokines [interleukin (IL)-12p70, IL-10, tumor necrosis factor and interferon gamma] released by human peripheral blood mononuclear cells after 24 h stimulation with 6 live yeast strains (Saccharomyces ssp.) and with bacterial reference strains. A murine model of acute 2-4-6-trinitrobenzene sulfonic acid (TNBS)-colitis was next used to evaluate the distinct prophylactic protective capacities of three yeast strains compared with the performance of prednisolone treatment.

Results: The six yeast strains all showed similar non-discriminating anti-inflammatory potential when tested on immunocompetent cells in vitro. However, although they exhibited similar colonization patterns in vivo, some yeast strains showed significant anti-inflammatory activities in the TNBS-induced colitis model, whereas others had weaker or no preventive effect at all, as evidenced by colitis markers (body-weight loss, macroscopic and histological scores, myeloperoxidase activities and blood inflammatory markers).

Conclusion: A careful selection of strains is required among the biodiversity of yeasts for specific clinical studies, including applications in inflammatory bowel disease and other therapeutic uses.