Bacteria may get most of the attention in the probiotic space, but yeasts can also be powerful in their benefits.
Saccharomyces boulardii and the gut
One well-characterized yeast called Saccharomyces boulardii (S. boulardii) can be beneficial in gut disorders. Several pre-clinical and clinical trials in animal models and humans respectively have demonstrated its efficacy as a probiotic.
In recent years, probiotics have been used as supplements in ulcerative colitis (UC) to help maintain a healthy microbiota. In addition to fighting pathogens such as Clostridium difficile and in temperance of Crohn’s disease, the probiotic S. boulardii has shown high efficacy in the treatment of UC.
Unfortunately, ulcerative colitis can set the stage for carcinogenesis. It does this by disrupting the microbiome and increasing inflammation. In one new study researchers explored the mechanism by which a probiotic yeast may inhibit that process. Saccharomyces boulardii alleviates ulcerative colitis carcinogenesis in mice by reducing TNF-α and IL-6 levels and functions and by rebalancing intestinal microbiota appeared in BMC Microbiology
Ulcerative colitis carcinogenesis
The cancerous process begins with inflammation which leads to dysplasia and tumors. Thus, chronic inflammation is a key factor of carcinogenesis in UC patients.Two pro-inflammatory cytokines abet the cascade: Tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6). And yes, studies have shown increased levels of TNF-α and IL-6 in UC patients.
Mice were treated with chemicals to induce carcinogenesis. The treatment group was lavaged with S. boulardii (5 × 107 CFU/d) for 12 weeks.
As expected, mice initially developed multiple colorectal tumors in the colon tissues, suggesting that TNF-α and IL-6 may be associated with tumor formation.
But after S. boulardii treatment, reduced carcinogenesis was observed in the mice i.e. reduced tumor load, reduced TNF-α and IL-6 levels in vivo, as well its effects on TNF-α and IL-6 activities in vitro.
In addition, changes in both fecal and mucosal microbiota were observed among the control, the chemically-treated, and the chemically-treated plus S. boulardii groups. See the study for specifics on microbial changes.
S. boulardii effectively reduced UC carcinogenesis in an AOM/DSS induced mice model. This positive result can likely be attributed to the reduction of TNF-α and IL-6 levels or the blockade of their function combined with alterations to the intestinal microbiota.
Saccharomyces boulardii is expanding its role in gut health. It is a reminder that yeasts may be valuable preventive and treatment probiotics. Improvement on probiotic function using engineered yeast is an attractive future direction.