Immune modulatory properties of selected bacterial strains on human dendritic cells

Background: Lactic acid bacteria (LAB) are important immune regulatory microorganisms and are considered to entertain health promoting effects which are of special interest in the view of the growing application of LAB in prevention and treatment of diseases. Aim of the study was to investigate the influence of different bacterial strains on the cytokine release by human monocyte-derived dendritic cells (MoDC). Method: Immature MoDC generated from peripheral blood monocytes of healthy non-atopic volunteers were stimulated with different Lactobacillus and Bifidobacterium strains in different concentrations (107- 105 cfu/ml). The cytokine profile (including IL-12p70, IL-10, IL-1β, IL-23, IL-6, TGFb) of stimulated MoDC was analyzed in supernatants after 24 h. Results: Stimulation of MoDC with bacteria revealed a highly strain-dependent induction of antiinflammatory IL-10 and pro-inflammatory cytokines such as IL- 12p70. High amounts of IL-10 produced by selected bacterial strains points to the induction of potentially functional regulatory T cell responses. Conclusion: The tested Lactobacillus and Bifidobacterium strains show specific straindependent immune modulatory capacities inducing a more pro- or antiinflammatory cytokine profile in human MoDC. Experiments of this study and future in vivo research in this field could contribute to the identification of a potential role for specific lactic acid bacteria as immune modulators in the prevention and treatment of several immune regulatory disorders and open new aspects for the application of bacterial strains as health promoting ingredients in food.