Bacteroides fragilis prevents Salmonella Heidelberg translocation in co-culture model mimicking intestinal epithelium
Résumé
<i>Salmonella</i> Heidelberg is one of the most common serovar causing foodborne illnesses. To limit the development of digestive bacterial infection, food supplements containing probiotic bacteria can be proposed. Commensal non-toxigenic <i>Bacteroides fragilis</i> has recently been suggested as a next-generation probiotic candidate. By using an original triple co-culture model including Caco-2 cells (representing human enterocytes), HT29-MTX (representing mucus-secreting goblet cells), and M cells differentiated from Caco-2 by addition of Raji B lymphocytes, bacterial translocation was evaluated. The data showed that <i>S.</i> Heidelberg could translocate in the triple co-culture model with high efficiency, whereas for <i>B. fragilis</i> a weak translocation was obtained. When cells were exposed to both bacteria, <i>S.</i> Heidelberg translocation was inhibited. The cell-free supernatant of <i>B. fragilis</i> also inhibited <i>S.</i> Heidelberg translocation without impacting epithelial barrier integrity. This supernatant did not affect the growth of <i>S.</i> Heidelberg. The non-toxigenic <i>B. fragilis</i> confers health benefits to the host by reducting bacterial translocation. These results suggested that the multicellular model provides an efficient <i>in vitro</i> model to evaluate the translocation of pathogens and to screen for probiotics that have a potential inhibitory effect on this translocation.