In vitro assessment of Saccharomyces cerevisiae cell fractions (YCF) using bovine epithelial cells and macrophages

Abstract Text: Since yeast Saccharomyces cerevisiae and its cell fractions (yeast cell fractions) are being used for the prevention and treatment of enteric diseases in different species, they may also be useful for preventing Johne’s disease, a chronic inflammatory bowel disease of ruminants caused by Mycobacterium avium spp. paratuberculosis (MAP). In this study, the adhesion of mCherry-labeled MAP to bovine mammary epithelial cells (Mac-T) co-cultured with CFs from two specific yeast strains (A and B)from the Lallemand culture collection was investigated. Additionally, bovine macrophages (BoMacs) were used to assess potential immunomodulatory properties of these yeast CFs by measuring BoMac viability, reactive oxygen species (ROS) production, and phagocytosis of mCherry-MAP. The Mac-T cells were treated for 6 hours with the two CFs at different concentrations (0.25, 0.5, 1, 2, 4, 8, and 16 mg/ml). The highest concentration of CFs that did not affect the Mac-T cell viability was 4 mg/ml for the strain A, and 2 mg/ml for strain B. Non-cytotoxic concentrations of yeast CFs from both strains reduced MAP adhesion to Mac-T cells in a concentration-dependent manner. BoMac cell viability was also assessed after a 6-hour treatment with both yeast CFs, and concentrations ≤ 4 mg/ml were deemed non-cytotoxic. BoMac ROS production was measured at non-cytotoxic yeast CF concentrations, and a dose-dependent increase in ROS production was found for both yeast CFs, with strain A being more potent than strain B. Finally, BoMac phagocytosis of m-Cherry-MAP, assessed after 6 hours, was prevented by co-culture with non-cytotoxic concentrations of yeast CFs. In summary, yeast CFs may be useful for preventing MAP adhesion to the gastrointestinal epithelium and for stimulating macrophage antimicrobial ROS production.  

Keywords: prebiotic, immunomodulation, bovine mammary epithelial cells (Mac-T)