Immunomodulatory Effects of Bifidobacterium longum W11 Produced Exopolysaccharide on Cytokine Production

Background: Health benefits, including immune modulating capability, exerted by Bifidobacterium strains have been attributed to their exopolysaccharides (EPSs). Objective: The effects of the purified EPS from B. longum W11 on cytokine production by peripheral blood mononuclear cells (PBMCs) alone or ConA-stimulated were investigated. Method: The production of IFN-gamma, IL-1 beta, IL-6 and IL-10 by PBMCs from healthy adult donors was analysed using purified EPS at two different concentrations (100 mu g/mL and 200 mu g/mL) and ConA, as an immunopotentiating marker. Moreover, the monosaccharide composition of the EPS from B. longum W11 was detected using HPLC analysis. Results: The results demonstrated the ability of purified EPS to increase the production of the tested cytokines, except IL-10, in ConA-stimulated PBMCs. In not-stimulated-PBMCs, EPS increased the production of IL-6 (at 200 mu g/mL) and IL-10 (at 100 mu g/mL). The HPLC analysis showed the presence of main monomers, galactose and glucose (ratio 1:1 wt/wt), and small amount of rhamnose. Conclusion: The results of this study demonstrate the ability of the EPS produced by B. longum W11 to interact in vitro with the human PBMCs, showing an immune-regulatory profile alone and an immune stimulatory profile in ConA-stimulated PBMCs. This suggests putative applications for the EPS from B. longum W11 in different pathological conditions.