Again, St1275 appeared to have stimulated significantly higher concentrations of IL-17 in all GIT co-cultured from buffy coat-derived PBMCs but lower concentrations or no production with CRL9850 or cord blood-derived PBMCs (Figs 1b and 2b). E. coli induced IL-10 secretion poorly from buffy coat PBMC. In contrast LAVRI-A1, B94, BL536,

ST1275 and LGG were found to stimulate high levels of IL-10 (Fig. 1b). From CRL9850 and cord blood-derived PBMCs, only LAVRI-A1, LGG, Bl536 and B94 induced significant (P < 0·05) levels of IL-10 production (Fig. 2a). Killed bacteria were able to induce substantial levels of all cytokines from buffy coat PBMC see more (Fig. 1c). Strikingly, only IL-10 was seen to be induced in significant amounts (P < 0·05) when

killed bacteria were incubated with the other cell types. PBMC incubation with LAB resulted in enhanced expression of CD25 on CD4+ T lymphocytes (Fig. 3), in line with Niers et al. SP600125 nmr [23]. To investigate whether treatment with lactobacilli or bifidobacteria lead to enhanced Th17 or Treg cell differentiation we assessed Th17/Treg populations in PBMC following 72–96 h of treatment with live or heat-killed bacteria. In all cases, following 72–96 h co-culture the number of Treg (CD4+CD25+FoxP3+) cells as a percentage of total PBMC increased substantially compared to untreated control cells, albeit to different levels [Fig. 4a(i) and a(ii)]. BL536 and B94 were found to be the most potent live strains and LAVRI-A1, B94 and St1275 the most potent heat-killed strains at inducing FoxP3 expression. The capacity of Y-27632 2HCl live or killed bacteria to induce IL-17-producing cells from PBMC was also

investigated. As shown in Fig. 4b, the number of IL-17-expressing CD3+CD4+ cells was increased substantially compared to control. Because Th17 cells typically produce IL-17 in culture, it was therefore likely that these cells were of the Th17 lineage. To confirm Th17 cell identity, extracellular marker CCR6 (CD196) and intracellular marker ROR-γt were subsequently used. The proportion of Th17 cells (CD3+CD4+CCR6+ROR-γt+) induced by live and killed bacteria was increased 2·5-fold above control [Fig. 4b(i) and b(ii)], with Bl536 being the most potent strain (P < 0·01). Interestingly, the induction of Th17 cells by the stimulation of PBMCs with E. coli or LPS were similar. Probiotic bacteria are commonly marketed to aid digestion and optimize microbial balance in the GIT. The current studies assessed the capacity of probiotic bacteria to affect the local cytokine production and regulatory cell populations among different cell types.