The molecular mechanism for activating IgA production by Pediococcus acidilactici K15 and the clinical impact in a randomized trial.

IgA secretion at mucosal sites is important for host defence against pathogens as well as maintaining the symbiosis with microorganisms present in the small intestine that affect IgA production. In the present study, we tested the ability of 5 strains of lactic acid bacteria stimulating IgA production, being Pediococcus acidilactici K15 selected as the most effective on inducing this protective immunoglobulin. We found that this response was mainly induced via IL-10, as efficiently as IL-6, secreted by K15-stimulated dendritic cells. Furthermore, bacterial RNA was largely responsible for the induction of these cytokines; double-stranded RNA was a major causative molecule for IL-6 production whereas single-stranded RNA was critical factor for IL-10 production. In a randomized, double-blind, placebo-controlled clinical trial, ingestion of K15 significantly increased the secretory IgA (sIgA) concentration in saliva compared with the basal level observed before this intervention. These results indicate that functional lactic acid bacteria induce IL-6 and IL-10 production by dendritic cells, which contribute to upregulating the sIgA concentration at mucosal sites in humans.

Inhibitory effect of cranberry polyphenol on cariogenic bacteria.

The purpose of this study was to investigate the effect of cranberry polyphenol fraction on mutans streptococci. Hydrophobicity is an important factor in the adherence of bacteria to the tooth surface. We found that cranberry polyphenol fraction significantly decreased the hydrophobicity of Streptococcus sobrinus 6715, Streptococcus mutans MT8148R and JC2 in a dose-dependent manner (p<0.05). Biofilm formation by S. sobrinus 6715 and S. mutans MT8148R was inhibited by 100 microg/ml cranberry polyphenol fraction (p<0.01). When dosage was increased to 500 microg/ml, biofilm formation by S. mutans JC2 was significantly inhibited (p<0.05). Addition of 500 microg/ml cranberry polyphenol fraction to medium inhibited growth of S. mutans MT8148R compared with the control (p<0.05).

Growth inhibitory action of cranberry on Helicobacter pylori.

BACKGROUND AND AIM: Cranberry is a fruit that originated in North America, and it has been used by Native Americans for bacterial infections. Recent studies have revealed it to be effective for preventing refractory urinary infections, while also suggesting that it plays a possible role in the eradication of Helicobacter pylori (H. pylori). METHODS: The H. pylori strains used in the present study were NCTC11637 and 11638. Sugar and organic acid-rich, and polyphenol-rich fractions were obtained from cranberry juice concentrate by Amberlite XAD7HP-column chromatography. The H. pylori growth inhibition was estimated by OD(660) and titration in liquid culture, and by an agar dilution plate method. The shapes of the bacteria were analyzed by scanning electron microscopy. RESULTS: Cranberry extract suppressed bacterial proliferation in a dose-dependent manner. In the comparison with other juices, polyphenol-rich fruits (cranberries, blueberries, and red grapes) showed similar growth inhibitory activity, whereas polyphenol-poor fruits (oranges, pineapples, apples, and white grapes) did not show any activity. The polyphenol-rich fraction of cranberry maintained the H. pylori-growth inhibitory activity. More bacteria in a coccoid form were observed after culture with cranberry. CONCLUSION: Cranberry extract inhibited H. pylori proliferation and it is suggested that polyphenols are responsible for this action. The morphological analysis suggested that cranberry induces H. pylori to develop a coccoid form, thereby inhibiting its growth bacteriostatically. Further basic studies to clarify these mechanisms in combination with in vivo studies are needed.

Anti-allergic activity of naringenin chalcone from a tomato skin extract.

The anti-allergic activity of a tomato extract was studied by using an in vitro histamine-release assay. The tomato skin extract exerted the strongest inhibition of histamine release. Chlorogenic acid, rutin and naringenin were identified in the 60% ethanol extract of tomato skin. However, the extract contained an unknown compound which strongly inhibited histamine release. This active compound in tomato skin was identified as naringenin chalcone (trans-2'4'6'4-tetrahydroxychalcone). Naringenin chalcone inhibited histamine release with an IC(50) value of 68 microg/ml. The anti-allergic activity of the tomato skin extract was next investigated by the in vivo mouse ear-swelling response. We found that naringenin chalcone showed the strongest inhibitory effect of the polyphenols of the tomato skin extract. These results indicate that a tomato skin extract could inhibit allergic reactions.