Yoshihiro Yamamoto

Kyushu University, Fukuoka-shi, Fukuoka-ken, Japan

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Publications (12)27.83 Total impact

  • Article: Enhanced immunomodulatory activity and stability in simulated digestive juices of Lactobacillus plantarum L-137 by heat treatment.
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    ABSTRACT: This study reports the effect of heat treating Lactobacillus plantarum L-137 on its in vitro cytokine-inducing activity, on the stability of this activity in simulated digestive juices, and on its in vivo immunomodulatory properties. L-137 cells were harvested at the stationary phase with or without the subsequent heat treatment and then lyophilized. Heat-killed L-137 cells stimulated mouse spleen cells to produce more interleukin-12p40 than unheated L-137. The interleukin-12p40-inducing activity of unheated L-137 was significantly lower when incubated with simulated intestinal juice, but the activity of heat-killed L-137 cells was maintained. Furthermore, heat-killed L-137 was more protective than unheated L-137 in a mouse model of dextran sulfate sodium-induced colitis. A heat treatment may therefore be effective for enhancing the immunomodulatory activity of L-137 cells.
    Bioscience Biotechnology and Biochemistry 05/2012; 76(5):918-22. · 1.28 Impact Factor
  • Article: Daily intake of heat-killed Lactobacillus plantarum L-137 enhances type I interferon production in healthy humans and pigs.
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    ABSTRACT: We have previously reported that oral administration of heat-killed Lactobacillus plantarum L-137 (HK L-137) stimulates innate immunity for production of type I interferon (IFN) which subsequently augments host defense against influenza A virus infection in mice. We here examined the effect of HK L-137 intake on type I IFN in humans. Sixteen subjects were randomly assigned to receive a tablet containing 10 mg of HK L-137 or a matching tablet for 8 weeks and the serum levels of type I IFN were examined before and after the first or second dose of the trivalent inactivated influenza vaccine. There were no differences in the seroresponse rate, the seroprotection rate and the geometric mean Ab titers after either the first or second dose of vaccine between the HK L-137 group and the control group. On the other hand, the levels of IFN-β were significantly higher in the HK L-137 group than in the control group before vaccination although the vaccination conferred little additional induction of IFN-β. We further examined IFN-β gene expression in the whole blood cells of pigs fed on a diet containing HK L-137 and found that the IFN-β mRNA levels were significantly higher in the HK L-137 group than in the control group. The finding that daily intake of HK L-137 enhances type I IFN production and host defense against influenza A virus infection in mice may be applied to at least two additional species.
    Immunopharmacology and Immunotoxicology 04/2012; · 1.83 Impact Factor
  • Article: Lipoteichoic acids on Lactobacillus plantarum cell surfaces correlate with induction of interleukin-12p40 production.
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    ABSTRACT: Heat-killed cells of Lactobacillus plantarum L-137 are potent inducers of IL-12 in vitro as well as in vivo and have been shown to have antiallergic, antitumor, and antiviral effects through this induction, which leads to a Th1 type immune response. To determine why L-137 cells induce much greater IL-12 production than the type strain Lactobacillus plantarum JCM1149, we examined the differences in their CW components. The L-137 CW was found to have a higher alanine content and IL-12p40 induction was significantly greater in comparison with JCM1149 CW, whereas peptidoglycans isolated from both strains did not cause IL-12p40 induction. Because in purified CW preparations from gram-positive bacteria, the presence of LTA, the major proinflammatory structure on these bacteria, has been known to have high alanine content, we investigated the responsiveness of both strains to anti-LTA antibody by flow cytometry. L-137 cells reacted more with anti-LTA antibody than did JCM1149 cells. Furthermore, derivative strains of L-137, cured of a specific plasmid pLTK11 of the 15 endogenous plasmids in wild-type L-137, had poor responsiveness to anti-LTA antibody and showed lower IL-12p40 inducing activity than the wild-type L-137 with pLTK11. Our results suggest that LTA expression on the cell surface causes IL-12p40 induction, and that the above internal plasmid of L-137 influences LTA synthesis and expression on the cell surface.
    Microbiology and Immunology 03/2010; 54(3):143-51. · 1.30 Impact Factor
  • Article: Oral administration of heat-killed Lactobacillus plantarum L-137 enhances protection against influenza virus infection by stimulation of type I interferon production in mice.
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    ABSTRACT: We have previously reported that heat-killed Lactobacillus plantarum L-137 (HK-LP) stimulates macrophage/dendritic cells to produce T helper (Th) 1-related cytokines in vitro and in vivo in mice. We here examined the effect of oral administration of HK-LP on protection against influenza virus infection in mice. C57BL/6 mice were orally given HK-LP from day -7 to 7 and intranasally infected with influenza virus A/FM/1/47 (H1N1, a mouse-adapted strain) at 100 pfu on day 0. The survival time was significantly prolonged in mice treated with HK-LP than that in mice treated with PBS as controls. The viral titers in the lung were significantly lower in mice treated with HK-LP than controls at the early stage after influenza virus infection. An appreciable level of interferon (IFN)-beta was detected in the serum of mice treated with HK-LP, while no IFN-beta was detected in controls after influenza infection. Our results suggest that HK-LP, a potent IFN-beta inducer, is useful for prevention against influenza infection.
    International immunopharmacology 06/2009; 9(9):1122-5. · 2.21 Impact Factor
  • Article: A combination of caffeine, arginine, soy isoflavones, and L-carnitine enhances both lipolysis and fatty acid oxidation in 3T3-L1 and HepG2 cells in vitro and in KK mice in vivo.
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    ABSTRACT: To develop an anti-obesity agent containing dietary components, we focused on the mechanisms that enhance both lipolysis and fatty acid oxidation. Caffeine and arginine (CA), a nonselective adenosine-receptor antagonist and an inducer of lipolytic hormone, respectively, were used to stimulate lipolysis. Soy isoflavones and L-carnitine (SL), stimulators of carnitine palmitoyl transferase 1A and a cofactor for beta-oxidation of fatty acids, respectively, were used to enhance fatty acid oxidation. Effects of a combination of CA and SL (CASL) on lipid metabolism were studied in vitro and in vivo. During 3T3-L1 differentiation, lipid accumulation was significantly lower in cells treated with CASL (50 micromol/L, 1 mmol/L, 1 micromol/L, and 1 mmol/L, respectively) compared with each alone. Lipolysis was also significantly greater in 3T3-L1 adipocytes treated with CASL (50 micromol/L, 1 mmol/L, 10 micromol/L and 0.5 mmol/L, respectively) compared with each alone. In addition, treatment with higher concentrations of CASL (2 mmol/L, 1 mmol/L, 10 micromol/L, and 1 mmol/L, respectively) significantly enhanced beta-oxidation in HepG2 cells. The effects of CASL-containing diets (250 mg, 6 g, 200 mg, and 1.5 g/kg diet, respectively) were studied in vivo. When KK mice were food deprived for 48 h and subsequently refed a fat-free diet for 72 h, hepatic triglyceride (TG) accumulation was significantly lower in mice fed CASL compared with the control mice. In addition, after obese KK mice were fed a low-fat diet for 2 wk, adipose tissue weights were significantly lower in those fed CASL, but not CA or SL alone, compared with the control mice. Plasma and liver TG levels were also lower in mice fed CASL than in the control mice. These results suggest that CASL is effective for controlling obesity.
    Journal of Nutrition 11/2007; 137(10):2252-7. · 3.92 Impact Factor
  • Article: Daily intake of heat-killed Lactobacillus plantarum L-137 augments acquired immunity in healthy adults.
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    ABSTRACT: Heat-killed Lactobacillus plantarum strain L-137 (HK-LP) is a potent inducer of IL-12 in vitro as well as in vivo in mice. HK-LP has been shown to suppress IgE production against food allergens, as well as tumor growth in mice, through IL-12 production, which induces the T helper (Th) 1 type immune response. To determine whether the intake of HK-LP influences immune function and the quality of life (QOL), a randomized, double-blind, placebo-controlled, parallel study was conducted in healthy subjects. Sixty subjects (30 men and 30 women, mean age 56.3 y) were randomly assigned to receive a capsule containing 10 mg of HK-LP daily or a matching capsule for 12 wk. Biomarkers for innate immunity such as the natural killer activity of peripheral blood mononuclear cells, neutrophil phagocytosis, and cell surface expression of CD64 on monocytes were measured every 4 wk. Biomarkers for acquired immunity such as concanavalin A (Con A)-induced proliferation, percentages of INF-gamma and IL-4-producing cluster of differentiation (CD)4(+) T cells (Th1:Th2 ratio), and the serum IgG4:IgG ratio were measured every 4 wk or at wk 0 and wk 12. Health-related QOL was assessed using a self-rating questionnaire with 26 items. Among the measured biomarkers, the percent change in Con A-induced proliferation and the Th1:Th2 ratio in the HK-LP group was greater than those in the control group (P = 0.036 and P = 0.002, respectively). The degree of improvement in QOL was higher in the HK-LP group than in the control group at wk 8 (P = 0.049) and tended to be higher at wk 12 (P = 0.092). These results suggest that a daily intake of HK-LP augments acquired immunity, especially Th1-related immune functions in healthy subjects, thereby improving the health-related QOL.
    Journal of Nutrition 01/2007; 136(12):3069-73. · 3.92 Impact Factor
  • Article: A nonradioisotope, enzymatic assay for 2-deoxyglucose uptake in L6 skeletal muscle cells cultured in a 96-well microplate.
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    ABSTRACT: A nonradioisotope, 96-well-microplate assay to evaluate glucose uptake activity in cultured cells has been developed. 2-Deoxyglucose (2DG) was detected by measuring a potent fluorophore, resorufin, generated after incubation with a single assay solution containing hexokinase, adenosine 5'-triphosphate, glucose 6-phosphate dehydrogenase, beta-nicotineamide adenine dinucleotide phosphate, diaphorase, and resazurin. This amplifying detection system could detect the fluorescence intensity induced by uptake of 2DG into L6 skeletal muscle cells, even at the level of cells cultivated in individual wells in a 96-well microplate. Using this assay system, the effects of insulin, cytochalasin B (hexose uptake inhibitor), LY294002 (inhibitor of glucose transporter translocation), and pioglitazone hydrochloride (insulin-sensitizing agent) on 2DG uptake into L6 myotubes could be assessed clearly. Therefore, our simple method may be useful for in vitro high-throughput screening and for evaluating regulators of glucose uptake.
    Analytical Biochemistry 05/2006; 351(1):139-45. · 3.00 Impact Factor
  • Article: Nigerooligosaccharides augments mitogen-induced proliferation and suppresses activation-induced apoptosis of human peripheral blood mononuclear cells.
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    ABSTRACT: Nigerooligosaccharides (NOS), a mixture of nigerose and nigerosylmaltooligosaccharides, consists of immunopotentiating oligosaccharides found in foodstuffs. We have previously reported that activation of peripheral blood mononuclear cells (PBMC) in response to concanavalin A (Con A) or a streptococcal preparation of OK-432 is augmented in healthy young adults and elderly subjects after the intake of NOS-supplemented syrup. A reappraisal of the data suggests that NOS augments proliferation but partly suppresses activation-induced apoptosis of PBMC in response to these mitogens. To confirm this hypothesis, PBMC from healthy male subjects were stimulated with Con A or OK-432 in the presence of nigerose at the concentrations at which it was detected in the blood of subjects who had ingested NOS-supplemented syrup. Cellular activation, specifically metabolic demand, viability and proliferation, was assessed from glucose consumption, by WST-1 colorimetry and by 5-bromo-2'-deoxy-uridine incorporation assay, respectively. The Con A-induced activation of PBMC in each measurement was significantly augmented by nigerose. OK-432-induced decreases in the viability of PBMC were significantly inhibited by nigerose. Stimulation of PBMC with Con A or OK-432 induced apoptosis, but nigerose suppressed such activation-induced cell death. These results indicated that nigerose activated PBMC in vitro in a manner similar to the process observed in vivo, providing further evidence for the effectiveness of consumption of NOS-supplemented syrup.
    Immunopharmacology and Immunotoxicology 09/2004; 26(3):387-99. · 1.83 Impact Factor
  • Article: Effects of intake of a mixture of thiamin, arginine, caffeine, and citric acid on adiposity in healthy subjects with high percent body fat.
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    ABSTRACT: We assessed the effects of intake of thiamin, arginine, caffeine, and citric acid (TACC) on lipid metabolism in healthy subjects. Thirty-one subjects with high percent body fat (> or = 25.0%) were randomly assigned to a 12-wk intervention with daily intake of TACC-supplemented tea (1.1, 1240, 52, and 540 mg, respectively; n=16) or control tea (n=15). The percent body fat decreased significantly during the intervention in both groups, especially in the TACC group. A percentage decrease in triceps skinfold was significantly greater in the TACC group than in the control group. The decrease in abdominal visceral fat in obese subjects was significantly greater in the TACC group than in the control group. Serum triglyceride was significantly lower during intervention than that during the non-intervention period in the TACC group. These results suggest that TACC may be effective in reducing body fat in obese subjects.
    Bioscience Biotechnology and Biochemistry 11/2003; 67(11):2325-33. · 1.28 Impact Factor
  • Article: Anti-obesity effects of a mixture of thiamin, arginine, caffeine, and citric acid in non-insulin dependent diabetic KK mice.
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    ABSTRACT: Anti-obesity effects of a mixture of thiamin, arginine, caffeine, and citric acid (TACC) were investigated in non-insulin dependent diabetic KK mice. Feeding of either arginine or caffeine significantly suppressed an increase in hepatic lipid contents in fasted-refed KK mice. In addition, each component admixed with a low-calorie diet effectively reduced adipose tissue weight in KK mice previously fed a high-calorie diet. The decrease in adipose tissue weight was greater with a mixture of arginine and caffeine, and much greater with TACC than with arginine or caffeine alone. Moreover, plasma insulin concentration was significantly lower in mice fed TACC than in control mice. The anti-obesity effects of TACC were also shown when it was supplemented with a tea beverage. Adipose tissue weight, hepatic triglyceride contents, and plasma insulin concentration were significantly lower in mice given TACC-supplemented tea than in control mice. These results suggest that TACC is effective in reducing adipose tissue mass as well as improving disorders in lipid metabolism.
    Journal of Nutritional Science and Vitaminology 03/2003; 49(1):56-63. · 1.20 Impact Factor
  • Article: Nigerooligosaccharides augments natural killer activity of hepatic mononuclear cells in mice.
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    ABSTRACT: Nigerooligosaccharides (NOS), a mixture of nigerose and nigerosylmaltooligosaccharides, is immunopotentiating oligosaccharides found in foodstuffs. Augmentation of natural killer (NK) activity by NOS was studied in vitro and in vivo in mice. In vitro treatment of hepatic mononuclear cells (MNC) from normal mice with 1 micro/ml NOS 17 h or just prior to the cytotoxicity assay enhanced their cytotoxicity against YAC-1 cells. NK activity of hepatic MNC was also enhanced in mice injected intraperitoneally with 0.4 mg NOS or in mice given 1% NOS solution orally as a drinking fluid. In association with the augmentation of NK activity, increase in the liver weight induced by intravenous inoculation of EL-4 tumor cells was significantly suppressed by intraperitoneal pretreatment with 0.4 mg NOS. Moreover, drinking 1% NOS significantly improved the survival curve of mice intravenously inoculated with EL-4 cells. Our results suggest that the immunopotentiating activity of NOS is exerted partly through the augmentation of NK activity.
    International Immunopharmacology 02/2002; 2(1):151-9. · 2.38 Impact Factor
  • Article: Antitumor effect of heat-killed Lactobacillus plantarum L-137 through restoration of impaired interleukin-12 production in tumor-bearing mice
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    ABSTRACT:  We have previously reported that heat-killed Lactobacillus plantarum L-137 is a potent inducer of interleukin-12 (IL-12) in vivo as well as in vitro in mice. In order to develop effective usage of L. plantarum L-137 for tumor immunotherapy, we examined its antitumor effect against DBA/2 mice inoculated with syngenic P388D1 tumor cells in different treatment schedules. Daily injection of L. plantarum L-137 from the day of tumor inoculation induced a steep increase in plasma IL-12 only after the first injection but not after subsequent injections, and had no effect on tumor growth and survival time. In contrast, daily injection of L. plantarum L-137 from the 7th day after tumor inoculation exerted a marked antitumor effect but such an effect was not evident in mice treated with L. plantarum L-137 twice a week from the 7th day. IL-12 production was considerably impaired at the first injection but steeply increased after the third injection in the mice injected daily with L. plantarum L-137 from the 7th day. Our results suggest that daily administration of L. plantarum L-137 is required to exert an antitumor effect at the late stages of tumor development when IL-12 production is considerably impaired.
    Cancer Immunology and Immunotherapy 04/2000; 49(3):157-164. · 3.70 Impact Factor