The Survival of and Cytokine Induction by Lactic Acid Bacteria after Passage Through a Gastrointestinal Model

The immunostimulatory properties of lactic acid bacteria which have been subjected to ecological conditions of the gut have not previously been studied. We analyzed the survival of three different Lactobacillus strains and of one Bifidobacterium strain in an in 6itro gastrointestinal model consisting of compartments corresponding to the human stomach and small intestine. Human peripheral blood mononuclear cells (PBMC) were stimulated with bacteria recovered from the stomach and the production of tumor necrosis factor alpha (TNF- α ), interleukin-6 (IL-6) and IL-10 in PBMC was measured. While the viability of all the strains in the stomach was similar during the measured 3 h, there were considerable differences in the ileum delivery. Despite the poor viability of the strains in the stomach, they still had a detectable ability to induce production of TNF- α and IL-6. Our results suggest that lactobacilli and bifidobacteria not even viable after passage through the stomach can influence the immune system. Keywords: lactobacilli, bifidobacteria, gastrointestinal model, cytokine induction.