The probiotic yeast, Saccharomyces boulardii ameliorates intestinal injury and inflammation caused by a variety of bacterial and viral pathogens.
In this study, researchers from the United States hypothesized that S. boulardii acts by modulating the host's intestinal inflammatory response.
Dr Stavros Sougioultzis's team aimed to identify specific mechanisms for the beneficial effects of S. boulardii. They examined the yeast's ability to influence host cell signaling and pro-inflammatory gene expression.
|The active component in S. boulardii is a small (≤1 kD), heat stable, water soluble molecule.|
|American Gastroenterological Association|
The team stimulated HT-29 human colonocytes and THP-1 human monocytes with interleukin (IL)-1 beta, tumor necrosis factor (TNF)-alpha, ToxA (Clostridium difficile Toxin A) or lipopolysaccharide (LPS). This was performed in the presence or absence of S. boulardii culture supernatant (SbS).
They measured the production of the pro-inflammatory chemokine IL-8 in the condition media by Enzyme-Linked Immunosorbent Assay.
The researchers also evaluated IL-8 mRNA levels by RT-PCR.
They measured the effect of SbS on I-kappa B alpha degradation using Western blotting, and on NF-kappa B-DNA binding using Electrophoretic Mobility Shift Assay (EMSA).
In addition, NF-kappa B-regulated gene expression was evaluated by transient transfection of THP-1 cells with an NF-kappa B-responsive luciferase reporter gene.
The researchers found that SbS inhibited IL-8 protein production in IL-1 beta stimulated HT-29 cells by 75% TNF alpha stimulated HT-29 cells by 85%, and ToxA stimulated HT-29 cells by 90% (<0.001 for each). It also prevented upregulation of IL-8 mRNA, as determined by RT-PCR.
The team observed a similar inhibitory effect in IL-1 beta or LPS-stimulated THP-1 cells.
Furthermore, SbS also prevented I kappa B alpha degradation, NF-kappa B - DNA binding and NF-kappa B-reporter gene up-regulation following THP-1 cell activation.
The research team also performed purification and characterization studies. These included cesium chloride density gradient ultra-centrifugation, gel filtration, and matrix assisted laser desorption time of flight mass spectroscopic examination. This analysis indicated that the active component in SbS is a small (≤1 kD), heat stable, water soluble molecule.
The team concluded that S. boulardii produced a soluble factor that inhibits NF-kappa B activation and NF-kappa B-mediated IL-8 gene expression in cytokine-, ToxA- or LPS-stimulated intestinal epithelial cells and monocytes.
They think that this anti-inflammatory factor may mediate S. boulardii's beneficial effects in intestinal disease.