Effects of specific lactic acid bacteria on the intestinal permeability to macromolecules and the inflammatory condition

Non-live probiotic bacteria and their fermentation products can be used in milk-based formula intended for healthy infants. The effects of a milk formula fermented with Bifidobacterium breve and Streptococcus thermophilus and heated/dehydrated to inactivate the micro-organisms have been reported over the last few years to decrease the intestinal permeability to macromolecules in experimental animals in vivo and more recently to down-regulate inflammatory condition in vitro. Feeding guinea-pigs with such dehydrated fermented milk reinforced the intestinal barrier resistance to food proteins (HRP, beta-lactoglobulin). In addition, the products secreted by bacteria were capable of inhibiting the lipopolysaccharide (LPS)-induced TNF-alpha secretion by human peripheral mononuclear blood cells. The active secretion products were resistant to digestive enzymes and their anti-inflammatory properties were preserved after transepithelial transport across the filter-grown intestinal epithelial cell line, especially in inflammatory conditions. The binding of LPS to monocytes as well as NF kappa B nuclear translocation leading to pro-inflammatory cytokine transcription were inhibited by bacteria-culture supernatants. Conclusion: B. breve and S. thermophilus used as non-live micro-organisms in fermented infant formula seem to induce a reduction in macromolecular absorption and release metabolites exerting an anti-TNF-alpha effect, which persists after intestinal transport. Thus, specific lactic acid bacteria and their metabolites seem to affect positively the intestinal function.