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An osteoblastic protein, osteocalcin (OC), exists in vivo in two forms: carboxylated OC, and uncarboxylated or low-carboxylated OC (ucOC). ucOC acts as a hormone to regulate carbon and energy metabolism. Recent studies demonstrated that ucOC exerts insulinotropic effects, mainly through the glucagon-like peptide 1 (GLP-1) pathway. GLP-1 is an insulinotropic hormone secreted by enteroendocrine L cells in the small intestine. Thus, efficient delivery of ucOC to the small intestine may be a new therapeutic option for metabolic diseases such as diabetes and obesity. Here, we genetically engineered a lactic acid bacterium, Lactococcus lactis, to produce recombinant mouse ucOC. Western blotting showed that the engineered strain (designated NZ-OC) produces and secretes the designed peptide (rOC) in the presence of nisin, an inducer of the recombinant gene. Highly-purified rOC was obtained from the culture supernatants of NZ-OC using immobilized metal affinity chromatography. An in vitro assay showed that purified rOC promotes GLP-1 secretion in a mouse intestinal neuroendocrine cell line, STC-1, in a dose-dependent manner. These results clearly demonstrate that NZ-OC secretes rOC, and that rOC can promote GLP-1 secretion by STC-1 cells. Genetically modified lactic acid bacteria (gmLAB) have been proposed over the last two decades as an effective and low-cost mucosal delivery vehicle for biomedical proteins. NZ-OC may be an attractive tool for the delivery of rOC to trigger GLP-1 secretion in the small intestine to treat diabetes and obesity. [ABSTRACT FROM AUTHOR]

The effects of Streptococcus thermophilus ST28 on cytokine production bymurine splenocytes stimulated with transforming growth factor-β plus interleukin- (IL-) 6 were evaluated. The addition of ST28 significantly repressed IL-17 production compared to ATCC 19258 (type strain). ST28 also decreased the number of Th17 cells in the stimulated splenocytes. The anti-inflammatory effects of ST28 administration were evaluated in mice with colitis induced by dextran sodium sulphate (DSS). Oral treatment of mice with ST28 ameliorated the intestinal lesions by DSS. Upon DSS treatment, IL-17 production in lamina propria lymphocytes (LPLs) was induced, but ST28 significantly decreased its production. ST28 also decreased the percentage of Th17 cells in LPL from DSSinduced colitis. The present results imply that ST28 suppresses the Th17 response in inflamed intestines and would be useful in the treatment of Th17-mediated diseases, such as inflammatory bowel disease. [ABSTRACT FROM AUTHOR]

Although some bacterial strains show potential to prevent colitis, their mechanisms are not fully understood. Here, we investigated the anti-colitic mechanisms of Bifidobacterium longum subsp. infantis JCM 1222T, focusing on the relationship between interleukin (IL)-17A secreting CD4+ T cells and intestinal epithelial costimulatory molecules in mice. Oral administration of JCM 1222T to mice alleviated dextran sulfate sodium (DSS)-induced acute colitis. The expression of type 1 helper T (Th1)- and IL-17 producing helper T (Th17)-specific cytokines and transcriptional factors was suppressed by JCM 1222T treatment. Intestinal epithelial cells (IECs) from colitic mice induced IL-17A production from CD4+ T cells in a cell-cell contact-dependent manner, and this was suppressed by oral treatment with JCM 1222T. Using blocking antibodies for costimulatory molecules, we revealed that epithelial costimulatory molecules including CD80 and CD40, which were highly expressed in IECs from colitic mice, were involved in IEC-induced IL-17A response. Treatment of mice and intestinal epithelial cell line Colon-26 cells with JCM 1222T decreased the expression of CD80 and CD40. Collectively, these data indicate that JCM 1222T negatively regulate epithelial costimulatory molecules, and this effect might be attributed, at least in part, to suppression of IL-17A in DSS-induced colitis. [ABSTRACT FROM AUTHOR]

The proinflammatory cytokine interleukin (IL)-17 plays important roles in various inflammatory diseases, and IL-17-producing T helper 17 cells (Th17) have received much attention. For therapy of Th17-mediated diseases, some reports have indicated the clinical efficacy of lactic acid bacteria, including Streptococcus thermophilus. In this study, we examined the mechanism for the suppressive effects of S. thermophilus ST28 on the Th17 response in murine splenocytes stimulated with transforming growth factor (TGF)-β plus IL-6. Stimulation with TGF-β plus IL-6 increased mRNA expression of IL-17 and its production in the splenocytes, but ST28 markedly suppressed both. Meanwhile, ST28 increased the mRNA expression of interferon (IFN)-γ as well as its production. Anti-IFN-γ completely cancelled the suppressive effect of ST28 on IL-17 production. From these data, it was concluded that IFN-γ induced by ST28 had an important role on the effect. A genomic DNA (10 µg/ml) from ST28 effectively suppressed IL-17 production, probably via the Toll-like receptor 9. Therefore, modulation of Th1/Th17 balance would be one of the mechanisms under which S. thermophilus ST28 exerts an anti-inflammatory effect.