Sialyllactose Enhances the Short-Chain Fatty Acid Production and Barrier Function of Gut Epithelial Cells via Nonbifidogenic Modification of the Fecal Microbiome in Human Adults.

Although various benefits of human milk oligosaccharides (HMOs) have been reported, such as promoting Bifidobacterium growth in the infant gut, their effects on adults have not been fully studied. This study investigated the effects of two types of sialyllactose, 3'-sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL), on the adult intestinal microbiome using the simulator of human intestinal microbial ecosystem (SHIME®), which can simulate human gastrointestinal conditions. HPLC metabolite analysis showed that sialyllactose (SL) supplementation increased the short-chain fatty acid content of SHIME culture broth. Moreover, 16S rRNA gene sequencing analysis revealed that SL promoted the growth of Phascolarctobacterium and Lachnospiraceae, short-chain fatty acid-producing bacteria, but not the growth of Bifidobacterium. Altogether, both types of SL stimulated an increase in short-chain fatty acids, including propionate and butyrate. Additionally, SHIME culture supernatant supplemented with SL improved the intestinal barrier function in Caco-2 cell monolayers. These results suggest that SL could act as a unique prebiotic among other HMOs with a nonbifidogenic effect, resulting in intestinal barrier protection.

Enhancement of immunomodulative effect of lactic acid bacteria on plasmacytoid dendritic cells with sucrose palmitate.

Plasmacytoid dendritic cells (pDCs) play a key role in the immune response against viruses. In addition, recent research has suggested that pDCs possess direct and indirect tumoricidal activities. We previously found that a lactic acid bacteria strain, Lactococcus lactis JCM 5805 (LC-Plasma), stimulated pDCs and prevented viral infection in mouse and human studies. Meanwhile, emulsifiers have recently been highlighted as candidate adjuvants for some viral vaccines and cancer immunotherapies. In this study, we discovered some specific emulsifiers, mainly consisting of sucrose fatty acid esters, that drastically enhance the potency of LC-Plasma to activate pDCs in vitro. The emulsifiers promoted the efficient uptake of LC-Plasma by pDCs and the ratio of pDCs that took up LC-Plasma correlated with the activity of pDCs. In addition, an in vivo study showed that oral treatment with LC-Plasma mixed with an emulsifier induced a higher expression of genes related to anti-viral immunity in the lung compared to treatment with LC-Plasma alone. Both LC-Plasma and the emulsifiers used in this study have been confirmed to be safe for human use. Therefore, LC-Plasma mixed with an emulsifier might be a useful tool for certain anti-cancer and anti-viral therapies.

Effects of oral intake of plasmacytoid dendritic cells-stimulative lactic acid bacterial strain on pathogenesis of influenza-like illness and immunological response to influenza virus.

Lactococcus lactis ssp. lactis JCM5805 has been shown to be a rare lactic acid bacterium that can activate plasmacytoid dendritic cells in both murine and human species. In this study, we carried out a randomised placebo-controlled double-blind experiment to evaluate its effect on the pathogenesis of influenza-like illness during the winter season. A total of 213 volunteers were divided into two groups, which received either yogurt made with L. lactis JCM5805 or a placebo beverage daily for 10 weeks. In the JCM5805 group, the cumulative incidence days of 'cough' and 'feverishness', which are defined as major symptoms of an influenza-like illness, were significantly decreased compared with the placebo group. In addition, peripheral blood mononuclear cells prepared from volunteers were cultured in the presence of inactivated human influenza virus A/H1N1 (A/PR/8/34). IFN-α elicited by A/H1N1 tended to be higher in the JCM5805 group compared with the placebo group, and an IFN-α-inducible antiviral factor, interferon-stimulated gene 15 (ISG15), elicited by A/H1N1 was significantly higher in the JCM5805 group compared with the placebo group after the intake period. These results suggest that intake of JCM5805 is able to prevent the pathogenesis of an influenza-like illness via enhancement of an IFN-α-mediated response to the influenza virus.

The combined effect of caffeine and ornithine on the mood of healthy office workers.

Caffeine is widely consumed and well known for stimulating the central nervous system. When developing new foods and beverages that contain caffeine, it is important to explore the potential synergistic effects of consuming amino acids and other food ingredients with caffeine on humans. Given the physiological pathways affected by the amino acid ornithine, consumption of ornithine with caffeine may have synergistic effects. The purpose of the present study was to examine the effect of consuming caffeine with ornithine in humans. The study used a randomized, placebo-controlled, double-blinded crossover design. The subjects were all healthy office workers who ingested the placebo, 100 mg caffeine, or 100 mg caffeine plus 200 mg ornithine in the morning and completed questionnaires about their mood. Office workers who consumed the combination of caffeine and ornithine had higher mood ratings 8 h after consumption than office workers who consumed caffeine alone. The results of the present study suggest that there is a unique synergistic effect between caffeine and ornithine on the mood of healthy office workers and that ornithine may potentiate the effects of caffeine.

Optimized mounting of a polyethylene naphthalate scintillation material in a radiation detector.

Polyethylene naphthalate (PEN) has great potential as a scintillation material for radiation detection. Here the optimum mounting conditions to maximize the light collection efficiency from PEN in a radiation detector are discussed. To this end, we have determined light yields emitted from irradiated PEN for various optical couplings between the substrate and the photodetector, and for various substrate surface treatments. The results demonstrate that light extraction from PEN is more sensitive to the optical couplings due to its high refractive index. We also assessed the extent of radioactive impurities in PEN as background sources and found that the impurities are equivalent to the environmental background level.

Nrf2 regulates ferroportin 1-mediated iron efflux and counteracts lipopolysaccharide-induced ferroportin 1 mRNA suppression in macrophages.

Iron is an essential element of hemoglobin, and efficient iron recycling from senescent erythrocytes by splenic macrophages is required for erythrocyte hemoglobin synthesis during erythropoiesis. Ferroportin 1 (Fpn1) is the sole iron exporter in mammals, and it also regulates iron reutilization. In this study, we demonstrated genetically that a redox-sensitive transcription factor, Nrf2, regulates Fpn1 mRNA expression in macrophages. Nrf2 activation by several electrophilic compounds commonly resulted in the upregulation of Fpn1 mRNA in bone marrow-derived and peritoneal macrophages obtained from wild-type mice but not from Nrf2 knockout mice. Further, Nrf2 activation enhanced iron release from the J774.1 murine macrophage cell line. Previous studies showed that inflammatory stimuli, such as LPS, downregulates macrophage Fpn1 by transcriptional and hepcidin-mediated post-translational mechanisms leading to iron sequestration by macrophages. We showed that two Nrf2 activators, diethyl maleate and sulforaphane (SFN; a natural Nrf2 activator found in broccoli), restored the LPS-induced suppression of Fpn1 mRNA in human and mouse macrophages, respectively. Furthermore, SFN counteracted the LPS-induced increase of Hepcidin mRNA by an Nrf2-independent mechanism in mouse peritoneal macrophages. These results demonstrate that Nrf2 regulates iron efflux from macrophages through Fpn1 gene transcription and suggest that Nrf2 may control iron metabolism during inflammation.

Macrophage as a target of quercetin glucuronides in human atherosclerotic arteries: implication in the anti-atherosclerotic mechanism of dietary flavonoids.

Epidemiological studies suggest that the consumption of flavonoid-rich diets decreases the risk of cardiovascular diseases. However, the target sites of flavonoids underlying the protective mechanism in vivo are not known. Quercetin represents antioxidative/anti-inflammatory flavonoids widely distributed in the human diet. In this study, we raised a novel monoclonal antibody 14A2 targeting the quercetin-3-glucuronide (Q3GA), a major antioxidative quercetin metabolite in human plasma, and found that the activated macrophage might be a potential target of dietary flavonoids in the aorta. Immunohistochemical studies with monoclonal antibody 14A2 demonstrated that the positive staining specifically accumulates in human atherosclerotic lesions, but not in the normal aorta, and that the intense staining was primarily associated with the macrophage-derived foam cells. In vitro experiments with murine macrophage cell lines showed that the Q3GA was significantly taken up and deconjugated into the much more active aglycone, a part of which was further converted to the methylated form, in the activated macrophages. In addition, the mRNA expression of the class A scavenger receptor and CD36, which play an important role for the formation of foam cells, was suppressed by the treatment of Q3GA. These results suggest that injured/inflamed arteries with activated macrophages are the potential targets of the metabolites of dietary quercetin. Our data provide a new insight into the bioavailability of dietary flavonoids and the mechanism for the prevention of cardiovascular diseases.

Identification of a serum component that regulates cyclooxygenase-2 gene expression in cooperation with 4-hydroxy-2-nonenal.

Atherosclerosis is a disorder of lipid metabolism as well as a chronic inflammatory disease. Cyclooxygenase-2 (COX-2), an inducible isoform responsible for high levels of prostaglandin production during inflammation and immune responses, mediates a variety of biological actions involved in vascular pathophysiology. We have previously shown that COX-2 gene expression is dramatically induced by a lipid-derived endogenous electrophile, 4-hydroxy-2-nonenal (HNE) (Kumagai, T., Matsukawa, N., Kaneko, Y., Kusumi, Y., Mitsumata, M., and Uchida, K. (2004) J. Biol. Chem. 279, 48389-48396). In the present study, based on the finding that HNE induced COX-2 expression only in the serum-containing media, we characterized a serum component essential for the HNE-induced COX-2 induction and found that low density lipoprotein (LDL) that had been denatured by freeze-thawing or oxidized LDL might be involved in the COX-2 induction. Moreover, we characterized the cellular events triggered by the combined stimulus of HNE and oxidized LDL and established that COX-2 induction is regulated by two sets of signaling mechanisms, one for the up-regulation of the scavenger receptor CD36 by HNE and one for the CD36-mediated COX induction by oxidized LDL. These findings represent a demonstration of a link between lipoprotein modification and activation of the inflammatory potential of macrophages.

Ebselen, a seleno-organic antioxidant, as an electrophile.

Ebselen [2-phenyl-1,2-benzisoselenazol-3(2H)-one], a seleno-organic compound showing glutathione peroxidase-like activity, is one of the promising synthetic antioxidants. In the present study, we investigated the electrophilic potential of this antioxidant and established the mechanism of the cysteine-targeted oxidation of protein. In addition, using ebselen as an electrophilic probe, we characterized the cysteine residues required for posttranslational modification into an electrophile sensor protein in the phase 2 detoxification response. Ebselen showed a potent antioxidant effect against the spontaneous and 4-hydroxy-2-nonenal-stimulated production of intracellular reactive oxygen species in rat liver epithelial RL34 cells. Meanwhile, upon in vitro incubation with a redox-active sulfhydryl protein (thioredoxin), ebselen showed a strong electrophilic potential of mediating the formation of selenenylsulfide and intra- and intermolecular disulfide linkages within the protein. By taking advantage of this antioxidant and electrophilic property of ebselen, we characterized posttranslational modification of Kelch-like ECH-associated protein 1 (Keap1), an electrophile sensor protein, which represses the ability of the transcription factor NF-E2-related factor 2 (Nrf2) upon induction of the phase 2 detoxification response. Ebselen potently induced the gene expression of a series of phase 2 enzymes in rat liver epithelial RL34 cells, which was associated with the formation of a high molecular weight complex of Keap1. Furthermore, a cysteine residue in Keap1, C151, was found to be uniquely required not only for the formation of the complex but also for the induction of the phase 2 response by ebselen. Thus, this unique antioxidant and electrophilic property of ebselen giving rise to the cysteine-targeted oxidation enabled us to evaluate the role of sensor cysteines in redox regulation of protein function under electrophile stress.