Lactobacilli and streptococci induce interleukin-12 (IL-12), IL-18, and gamma interferon production in human peripheral blood mononuclear cells

Abstract

Human peripheral blood mononuclear cells (PBMC) were stimulated with three nonpathogenic Lactobacillus strains and with one pathogenic Streptococcus pyogenes strain, and cytokine gene expression and protein production were analyzed. All bacteria strongly induced interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor alpha mRNA expression and protein production. S. pyogenes was the most potent inducer of secretion of IL-12 and gamma interferon (IFN-gamma), and two of three Lactobacillus strains induced IL-12 and IFN-gamma production. All strains induced IL-18 protein production. IL-10 and IL-4 production was induced weakly and not at all, respectively. Our data show that nonpathogenic lactobacilli and pathogenic streptococci can induce Th1 type cytokines IL-12, IL-18, and IFN-gamma in human PBMC.

Figures

FIG. 1

ELISA measurements of cytokine production in PBMC induced by L. rhamnosus E509, L. rhamnosus E522, L. bulgaricus E585, and S. pyogenes IH32030. PBMC (6 × 106/ml) were stimulated with 6 × 106 live bacteria per ml for 6 h (hatched bars) or 16 h (black bars). Results are means of three independent experiments, each done with PBMC from three or four donors. Error bars represent standard deviations of the means.

FIG. 2

Northern blot analysis of cytokine production in PBMC induced by LPS, L. rhamnosus E509, L. rhamnosus E522, L. bulgaricus E585, and S. pyogenes IH32030. PBMC (6 × 106/ml) from four donors were stimulated with 6 × 106 live bacteria per ml or with 100 ng of LPS per ml for 6 or 16 h.

FIG. 3

Kinetics of cytokine production in PBMC induced by S. pyogenes IH32030. PBMC (6 × 106/ml) from four donors were stimulated with 6 × 106 live bacteria per ml or with 100 ng of LPS per ml for 2, 6, or 16 h and then prepared for Northern blot analysis.

FIG. 4

Kinetics of cytokine production in PBMC induced by L. rhamnosus E522. PBMC (6 × 106/ml) from four donors were stimulated with 6 × 106 live bacteria per ml or with 100 ng of LPS per ml for 2, 6, or 16 h and then prepared for Northern blot analysis.