Biomedical subjects

Y Yoshikai

Publications and source records attributed to Y Yoshikai.

At least 19 recordsLinked to original sources

PubMed2006

Levan (beta-2, 6-fructan), a major fraction of fermented soybean mucilage, displays immunostimulating properties via Toll-like receptor 4 signalling: induction of interleukin-12 production and suppression of T-helper type 2 response and immunoglobulin E production.

BACKGROUND: Products from the fermentation process of soybeans by Bacillus subtilis (natto) have been shown to possess anti-tumour and immunomodulatory activities. However, the formulations previously examined were not chemically pure, and this is a major limitation for elucidation of the molecular mechanisms for their activities. OBJECTIVE: In order to determine which components in soybean mucilage exert immunostimulatory activities, we examined the activities of their purified forms in vitro and in vivo in mice. METHODS: B. subtilis (natto) and fractions including levan and poly-gamma-glutamic acid (gamma-PGA) from fermented soybean mucilage were prepared. Levels of cytokine production by mouse macrophage cells after treatment with the fractions were measured by means of ELISA. In vivo effect of levan delivered intragastrically on ovalbumin (OVA)-specific T-helper type 2 (Th2) response with IgE production was examined in BALB/c mice that had been immunized intraperitoneally with OVA. Results Levan but neither gamma-PGA nor killed B. subtilis (natto) was found to exert strong activity to induce production of IL-12 p40 and TNF-alpha by macrophage cell lines in vitro. RESULTS: of experiments using Toll-like receptor (TLR) 4-deficient mice and TLR4-transfected human cell line indicated that TLR4 is involved in pattern recognition of levan. Oral administration of levan in vivo significantly reduced the serum levels of OVA-specific IgE and Th2 response to OVA in mice immunized with OVA. CONCLUSION: Levan is an immunostimulatory moiety in products from the fermentation process of B. subtilis (natto) and may be useful for prevention of allergic disorders with IgE production.

Adjuvants, Immunologic↗

PubMed2006

Novel roles of osteopontin and CXC chemokine ligand 7 in the defence against mycobacterial infection.

Granulocyte-macrophage colony-stimulating factor (GM-CSF)-induced human monocyte-derived macrophage (GM-Mphi) or macrophage CSF (M-CSF)-induced human monocyte-derived Mphi (M-Mphi) are distinct in terms of the resistance to Mycobacterium tuberculosis. To elucidate the role of molecules involved in the functional differences between these Mphis, we investigated the gene expression profiles using microarray. After culture of CD14+ monocytes with CSFs, Mphis were cultured with or without bacillus Calmette-Guérin (BCG) (GM-Mphi-BCG and M-Mphi-BCG). The gene expression profiles from these cells were compared. Chemokines highly expressed in M-Mphis were selected and evaluated for anti-mycobacterial activity and superoxide production. FN1 and FCGR2B were the most up-regulated genes in GM-Mphi and M-Mphi, respectively. After stimulation with BCG, three chemokine genes (Osteopontin (SPP1), CXC chemokine ligand 7 (CXCL7) and CC chemokine ligand 11 (CCL11)) were highly expressed in M-Mphi-BCG when compared to those in GM-Mphi-BCG. A significantly increased resistance to M. tuberculosis H37Ra was observed after the stimulation of GM-Mphi with SPP1 or CXCL7. Superoxide production levels of SPP1- or CXCL7-stimulated GM-Mphis were higher than those of GM-Mphis without stimulation. These results indicate that both SPP1 and CXCL7 might have a role in the resistance against mycobacteria, at least in part, through augmenting reactive oxygen intermediate production in Mphis.

BCG Vaccine↗

PubMed2005

Role of interleukin 15 in colitis induced by dextran sulphate sodium in mice.

BACKGROUND AND AIMS: Interleukin (IL)-15 is a member of the IL-2 family, stimulating dendritic cells, natural killer (NK) cells, NK T cells and memory CD8+ T cells. IL-15 levels were elevated in the intestinal mucosa of inflammatory bowel diseases. Here we investigated the involvement of IL-15 in the pathogenesis of acute and chronic dextran sulphate sodium (DSS) induced colitis. METHODS: IL-15 knockout (KO) mice and control C57BL/6 mice were used to induce colitis with DSS in their drinking water. Survival rate, clinical activity of diseases, extent of tissue damage, leucocyte population, and cytokine production of lamina propria (LP) cells of the large intestines were assessed. RESULTS: IL-15 KO mice exhibited resistance to DSS induced acute colitis, as reflected by lower lethality, weight loss, clinical scores, and histological scores compared with those in control mice (p<0.05). The proportions of CD44(high) CD8+ T cells and NK cells in LP cells and levels of interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha, and IL-12p40 in culture supernatants of LP cells were reduced in IL-15 KO mice (p<0.05). In vivo depletion of CD8+ T cells and NK cells decreased levels of IFN-gamma, TNF-alpha, and IL-12p40 in culture supernatants of LP cells in C57BL/6 mice (p<0.01). In chronic colitis, weight loss and clinical scores were improved and levels of IFN-gamma, TNF-alpha, and IL-12p40 in culture supernatants of LP cells were also reduced in IL-15 KO mice (p<0.05). CONCLUSIONS: IL-15 plays an important role in the pathogenesis of both acute and chronic colitis induced by DSS in mice.

Acute Disease↗

PubMed2005

Toll-like receptors 2 and 4 are differentially involved in Fas dependent apoptosis in Peyer's patch and the liver at an early stage after bile duct ligation in mice.

BACKGROUND AND AIMS: Surgical management of extrahepatic cholestasis is frequently complicated by bacterial translocation and severe liver injury. The aim of this study was to clarify the involvement of Toll-like receptors (TLRs) in the pathogenesis of bacterial translocation and liver injury in obstructive cholestasis. METHODS: TLR2 deficient (TLR2(-/-)), MyD88(-/-), Jalpha281(-/-), gld/gld, and lpr/lpr mice, all of which have a C57BL/6 background, and C3H/HeN and TLR4 mutated C3H/HeJ mice were subjected to bile duct ligation (BDL). Faecal IgA and serum alanine aminotransferase levels were determined after BDL. Apoptosis was examined by histological and flow cytometric analyses of cells from Peyer's patches and the liver. RESULTS: The size and number of B cells in Peyer's patches markedly decreased on day 3 after BDL. Increased apoptosis in Peyer's patch B cells was evident on day 1 after BDL in control mice but not in lpr/lpr, MyD88(-/-), or C3H/HeJ mice. On the other hand, TLR2 and Fas ligand expression on intrahepatic NK1.1(+) T cells increased on day 1 after BDL in C57BL/6 mice. Liver injury and apoptosis were evident on day 1 after BDL in control and C3H/HeJ mice but were significantly reduced in TLR2(-/-), Jalpha281(-/-), gld/gld, and lpr/lpr mice. CONCLUSIONS: TLR4 and TLR2 may play important roles in Fas dependent apoptosis in Peyer's patch B cells and hepatocytes, respectively, at an early stage after BDL in mice.

Alanine Transaminase↗

PubMed2003

Cot/Tpl2 is essential for RANKL induction by lipid A in osteoblasts.

Lipopolysaccharide (LPS) is a pathogenic factor that increases bone resorption in periodontal diseases. LPS treatment of osteoblasts was shown to induce the receptor activator of NF-kappa B ligand (RANKL), an essential secretory or membrane-bound factor for osteoclast function, in a manner dependent on extracellular signal-regulated kinase (ERK) activation. However, the mechanisms regulating this process remained unknown. Here, we show that RANKL mRNA induction and ERK activation, when treated with synthetic lipid A (an active center of LPS), were markedly reduced in mouse osteoblasts lacking Cot/Tpl2, which was recently recognized as an essential kinase for the induction of TNF-alpha by LPS in macrophages. In contrast, c-Jun N-terminal kinase (JNK), p38 kinase, Raf-1, and NF-kappa B were normally activated in cot/tpl2-/- osteoblasts. These findings indicate that Cot/Tpl2 is essential for LPS-induced ERK activation and RANKL induction in osteoblasts.

Animals↗

PubMed2001

Syndecan-4 deficiency leads to high mortality of lipopolysaccharide-injected mice.

Syndecan-4 is a transmembrane heparan sulfate proteoglycan belonging to the syndecan family. Following intraperitoneal injection of lipopolysaccharide (LPS), syndecan-4-deficient mice exhibited high mortality compared with wild-type controls. Severe endotoxin shock was observed in the deficient mice: systolic blood pressure and left ventricular fractional shortening were lower in the deficient mice than in the wild-type controls 9 h after LPS injection. Although histological examinations revealed no apparent differences between two groups, the plasma level of interleukin (IL)-1beta was higher in the deficient mice than in the wild-type controls 9 h after LPS injection. Consistent with the regulatory roles of syndecan-4, its expression in monocytes and endothelial cells of microvasculature increased in the wild-type mice after LPS administration. Although IL-1beta was produced to the same extent by macrophages from syndecan-4-deficient and wild-type mice after LPS stimulation, inhibition of its production by transforming growth factor-beta1 was impaired in the syndecan-4-deficient macrophages. These results indicate that syndecan-4 could be involved in prevention of endotoxin shock, at least partly through the inhibitory action of transforming growth factor-beta1 on IL-1beta production.

Animals↗

PubMed2001

Overexpression of IL-15 in vivo enhances protection against Mycobacterium bovis bacillus Calmette-Guérin infection via augmentation of NK and T cytotoxic 1 responses.

To investigate the immunomodulating effects of IL-15 in vivo on mycobacterial infection, we used IL-15-transgenic (Tg) mice, which were recently constructed with cDNA-encoding secretable isoform of IL-15 precursor protein under the control of a MHC class I promoter. The IL-15-Tg mice exhibited resistance against infection with Mycobacterium bovis bacillus Calmette-Guérin (BCG), as assessed by bacteria growth. IFN-gamma level in serum was significantly higher in IL-15-Tg mice than in non-Tg mice after BCG infection. NK cells were remarkably increased, and Ag-specific T cytotoxic 1 response mediated by CD8+ T cells producing IFN-gamma was significantly augmented in the IL-15-Tg mice following BCG infection. Neutralization of endogenous IFN-gamma by in vivo administration of anti-IFN-gamma mAb deteriorated the clearance of the bacteria. Depletion of of NK cells or CD8+ T cells by in vivo administration of anti-asialo-GM(1) Ab or anti-CD8 mAb hampered the exclusion of bacteria. Thus, overexpression of IL-15 in vivo enhanced protection against BCG infection via augmentation of NK and T cytotoxic 1 responses.

Adjuvants, Immunologic↗

PubMed2001

Interleukin-15 prevents mouse mast cell apoptosis through STAT6-mediated Bcl-xL expression.

Interleukin (IL)-15 is a member of the cytokine family with T and natural killer (NK) cell growth-promoting activity. In mast cells, however, IL-15 uses a distinct receptor system different from that used in T and NK cells. We recently reported that IL-15 induces STAT6 activation and IL-4 production in a mouse mast cell line (MC/9) and bone marrow-derived mast cells. In the present study, we have demonstrated that IL-15 prevents MC/9 and bone marrow-derived mast cell apoptosis induced by factor withdrawal or anti-Fas antibody treatment. IL-15 increased mRNA and protein levels of an anti-apoptotic protein (Bcl-x(L)) in these cells, whereas bcl-2 mRNA remained unchanged. In addition, the transcriptional activity of the bcl-x(L) promoter was increased by IL-15 in MC/9 cells. In an electrophoretic mobility shift assay, IL-15 induced STAT6 binding to the STAT recognition site in the bcl-x(L) gene promoter. Furthermore, the expression of a dominant-negative form of STAT6 abrogated the effects of IL-15 on both bcl-x(L) mRNA up-regulation and prevention of apoptosis in mast cells. Altogether, our results suggest that IL-15 plays an important role in maintaining the number of mast cells through Bcl-x(L) expression mediated by STAT6.

Animals↗

PubMed2001

NF-kappa B and STAT5 play important roles in the regulation of mouse Toll-like receptor 2 gene expression.

Toll-like receptor 2 (TLR2) is involved in the innate immunity by recognizing various bacterial components. We have previously reported that TLR2 gene expression is rapidly induced by LPS or inflammatory cytokines in macrophages, and by TCR engagement or IL-2/IL-15 stimulation in T cells. Here, to investigate the mechanisms governing TLR2 transcription, we cloned the 5' upstream region of the mouse TLR2 (mTLR2) gene and mapped its transcriptional start site. The 5' upstream region of the mTLR2 gene contains two NF-kappa B, two CCAAT/enhancer binding protein, one cAMP response element-binding protein, and one STAT consensus sequences. In mouse macrophage cell lines, deletion of both NF-kappa B sites caused the complete loss of mTLR2 promoter responsiveness to TNF-alpha. NF-kappa B sites were also important but not absolutely necessary for LPS-mediated mTLR2 promoter activation. In T cell lines, mTLR2 responsiveness to IL-15 was abrogated by the 3' NF-kappa B mutation, whereas 5' NF-kappa B showed no functional significance. The STAT binding site also seemed to contribute, as the deletion of this sequence significantly reduced the IL-15-mediated mTLR2 promoter activation. EMSAs confirmed nuclear protein binding to both NF-kappa B sites in macrophages following LPS and TNF-alpha stimulation and to the 3' NF-kappa B site in T cells after IL-15 treatment. Thus, NF-kappa B activation is important but differently involved in the regulation of mTLR2 gene expression in macrophages and T cells following LPS or cytokine stimulation.

5' Untranslated Regions↗

PubMed2001

Gene expression of osteoclast differentiation factor is induced by lipopolysaccharide in mouse osteoblasts via Toll-like receptors.

Osteoclast differentiation factor (ODF), a recently identified cytokine of the TNF family, is expressed as a membrane-associated protein in osteoblasts and stromal cells. ODF stimulates the differentiation of osteoclast precursors into osteoclasts in the presence of M-CSF. Here we investigated the effects of LPS on the gene expression of ODF in mouse osteoblasts and an osteoblast cell line and found that LPS increased the ODF mRNA level. A specific inhibitor of extracellular signal-regulated kinase or protein kinase C inhibited this up-regulation, indicating that extracellular signal-regulated kinase and protein kinase C activation was involved. A protein synthesis inhibitor, cycloheximide, rather enhanced the LPS-mediated increase of ODF mRNA, and both a neutralizing Ab of TNF-alpha and a specific inhibitor of PGE synthesis failed to block the ODF mRNA increase by native LPS. Thus, LPS directly induced ODF mRNA. Mouse osteoblasts and an osteoblast cell line constitutively expressed Toll-like receptor (TLR) 2 and 4, which are known as putative LPS receptors. ODF mRNA increases in response to synthetic lipid A were defective in primary osteoblasts from C3H/HeJ mice that contain a nonfunctional mutation in the TLR4 gene, suggesting that TLR4 plays an essential role in the process. Altogether, our results indicate that ODF gene expression is directly increased in osteoblasts by LPS treatment via TLR, and this pathway may play an important role in the pathogenesis of LPS-mediated bone disorders, such as periodontitis.

Animals↗

PubMed2001

Overexpression of IL-15 in vivo enhances Tc1 response, which inhibits allergic inflammation in a murine model of asthma.

IL-15, a pleiotropic cytokine, is involved in the inflammatory responses in various infectious and autoimmune diseases. We have recently constructed IL-15-transgenic (Tg) mice, which have an increased number of memory-type CD8+ T cells in the peripheral lymphoid tissues. In the present study, we found that eosinophilia and Th2-type cytokine production in the airway were severely attenuated in OVA-sensitized IL-15-Tg mice following OVA inhalation. IL-15-Tg mice preferentially developed Tc1 responses mediated by CD8+ T cells after OVA sensitization, and in vivo depletion of CD8+ T cells by anti-CD8 mAb aggravated the allergic airway inflammation in IL-15-Tg mice following OVA inhalation. Adoptive transfer of CD8+ T cells from OVA-sensitized IL-15-Tg mice into normal mice before OVA sensitization suppressed Th2 response to OVA in the normal mice. These results suggest that overexpression of IL-15 in vivo suppresses Th2-mediated-allergic airway response via induction of CD8+ T cell-mediated Tc1 response.

Adoptive Transfer↗

PubMed2001

Memory phenotype CD8(+) T cells in IL-15 transgenic mice are involved in early protection against a primary infection with Listeria monocytogenes.

We recently constructed IL-15 transgenic (Tg) mice using cDNA encoding a secretable isoform of the IL-15 precursor protein under the control of an MHC class I promoter. The IL-15 Tg mice exhibited resistance against a primary infection with Listeria monocytogenes. The numbers of memory CD8(+) T cells were markedly increased in the IL-15 Tg mice following Listeria infection accompanied by sustained IL-15 production. The increased CD44(+)CD8(+) T cells in the infected IL-15 Tg mice were not specialized to recognize Listeria-specific antigen but produced a large amount of IFN-gamma in response to bystander stimulation exogenous IL-15 in combination with IL-12. Furthermore, Listeria-specific Th1 response by CD4(+) T cells was significantly augmented in the IL-15 Tg mice compared with control mice following Listeria infection. In vivo depletion of the CD8(+) T cells by anti-CD8 monoclonal antibody and adoptive transfer of the T cells from naive IL-15 Tg mice indicated that the CD8(+) T cells functioned not only to eliminate bacteria at the early stage of infection but also to promote Th1 response to L. monocytogenes. Overexpression of IL-15 shed light on a novel role of memory CD8(+) T cells in early protection and promotion of Th1 response against a primary infection with L. monocytogenes.

Adoptive Transfer↗

PubMed2001

Bilirubin impairs bactericidal activity of neutrophils through an antioxidant mechanism in vitro.

BACKGROUND: Liver failure accompanied by hyperbilirubinemia after major hepatic resection is profoundly associated with septic complications. Although the immune dysfunction in cholestasis has been intensively investigated, the contribution of increased serum bilirubin to the impaired resistance to bacterial infection remains to be elucidated. Because bilirubin possesses an antioxidant activity, we hypothesized that bilirubin may scavenge reactive oxygen species (ROS) produced by neutrophils and consequently impair neutrophil bacterial killing. To address this, we evaluated the effects of bilirubin on the bactericidal activity of ROS or of neutrophils in vitro. MATERIALS AND METHODS: The antioxidant activity of bilirubin was determined using an ROS-sensitive fluorophore, dichlorofluorescin diacetate (DCFH-DA). Bilirubin concentration in the buffer solution was monitored spectorophotometrically after incubation with ROS. The effect of bilirubin on killing of Escherichia coli by ROS or by isolated human neutrophils was determined by counting the viable E. coli after incubation on nutrient agar. RESULTS: The bilirubin concentration in the buffer solution was decreased by the addition of hydrogen peroxide, especially in the presence of peroxidase or ferrous iron. DCFH-DA oxidation by ROS or activated neutrophils was inhibited by bilirubin in a dose-dependent manner. The bactericidal activity of ROS or of isolated neutrophils was significantly attenuated by bilirubin. CONCLUSIONS: Bilirubin impairs bactericidal activity of neutrophils through scavenging ROS. Increased levels of serum bilirubin may well be responsible for the impaired bacterial clearance in patients with hyperbilirubinemia.

Antioxidants↗

PubMed2001

Characterization of CD28(-)CD4(+) T cells in living kidney transplant patients with long-term allograft acceptance.

CD28(-)CD4(+) T-cell subpopulation is expanded in kidney allograft patients with long graft survival. To seek for the roles of CD28(-)CD4(+) T cells in the long-term acceptance of kidney allografts, we characterized this population by analyzing cell surface molecules, TCR V(beta) repertoire, mixed lymphocyte reaction (MLR), and cytokine production. The number of CD28(-)CD4(+) T cells increased correlatively with time after transplantation in this group of patients. The CD28(-)CD4(+) T cells did not express detectable levels of CD25, CD69, V(alpha)24, or CTLA-4 but expressed heterogeneous amounts of CD45 RA on the surface. Freshly sorted CD28(-)CD4(+) T cells revealed a restricted V(beta) repertoire, whereas the V(beta) usage of CD28(+)CD4(+) T cells from the same patients was much diversified. Expression levels of TGF-beta and IFNgamma gene were significantly higher in the CD28(-) CD4(+) T cells than in the CD28(+)CD4(+) T cells from the kidney allograft patients. These findings suggest that an oligoclonal CD28(-) CD4(+) T-cell population is continuously activated in patients with long allograft survival, which may be linked with the long-term acceptance.

Adult↗

PubMed2001

Dichotomous effect of a traditional Japanese medicine, bu-zhong-yi-qi-tang on allergic asthma in mice.

To determine the potentiality of prophylactic and/or therapeutic approaches using a traditional herbal medicine, Bu-zhong-yi-qi-tang (Japanese name: Hochu-ekki-to, HOT), for the control of allergic disease, we examined the effects of oral administration of HOT on a murine model of asthma allergic responses. When oral administration of HOT was begun at the induction phase immediately after OVA sensitization, eosinophilia and Th2-type cytokine production in the airway were reduced in OVA-sensitized mice following OVA inhalation. The serum levels of OVA-specific immunoglobulin (Ig)E and IgG1 were significantly decreased, whereas the level of OVA-specific IgG2a was increased. Interleukin (IL)-4 production by spleen T cells in response to OVA was significantly suppressed, while Interferon (IFN)-gamma production was increased in mice treated with HOT in the induction phase. On the other hand, HOT given in the eliciting phase induced a predominant Th2 response with increased IgE production in OVA-sensitized mice following OVA inhalation. These results suggest that the oral administration of HOT dichotomously modulates allergic inflammation in a murine model for asthma, thus offering a different approach for the treatment of allergic disorders.

Administration, Oral↗

PubMed2001

Thymus-dependent modulation of Ly49 inhibitory receptor expression on NK1.1+gamma/delta T cells.

Major histocompatibility complex (MHC) class I-specific inhibitory receptors are expressed not only on natural killer (NK) cells but also on some subsets of T cells. We here show Ly49 expression on gamma/delta T cells in the thymus and liver of beta2-microglobulin-deficient (beta2m-/-) and C57BL/6 (beta2m+/+) mice. Ly49C/I or Ly49A receptor was expressed on NK1.1+gamma/delta T cells but not on NK1.1-gamma/delta T cells. The numbers of NK1.1+gamma/delta T cells were significantly smaller in beta2m+/+ mice than in beta2m-/- mice with the same H-2b genetic background. Among NK1.1+gamma/delta T cells, the proportions of Ly49C/I+ cells but not of Ly49A+ cells, were decreased in beta2m+/+ mice, suggesting that cognate interaction between Ly49C/I and H-2Kb is involved in the reduction of the number of Ly49C/I+ gamma/delta T cells in beta2m+/+ mice. The frequency of Ly49C/I+ cells in NK1.1+gamma/delta T cells was lower in both lethally irradiated beta2m+/+ mice transplanted with bone marrow (BM) from beta2m-/- mice and lethally irradiated beta2m-/- mice transplanted with BM from beta2m+/+ mice than those in adult thymectomized BM-transplanted chimera mice. These results suggest that reduction of Ly49C/I+ NK1.1+gamma/delta T cells in beta2m+/+ mice is at least partly due to the down-modulation by MHC class I molecules on BM-derived haematopoietic cells or radioresistant cells in the thymus.

Animals↗

PubMed2001

Roles of prostaglandins and leukotrienes in acute inflammation caused by bacterial infection.

Prostanoids, including prostaglandins and thromboxanes, are generated by the phospholipase A2/cyclooxygenase pathway, and leukotrienes are generated by the 5-lipoxygenase pathway from arachidonic acid. At physiological concentrations, vasodilator prostaglandins enhance the vascular permeability effects of histamine and bradykinin, and leukotrienes are important mediators of leukocyte accumulation during acute inflammation. On the other hand, prostaglandin metabolites such as cyclopentenone prostaglandins contribute to the resolution of acute inflammation through inhibition of nuclear factor-kappaB activation. Thus, arachidonic acid oxygenation products mediate diverse effects that induce and resolve acute inflammation caused by bacterial infection.

Acute Disease↗

PubMed2001

Mice lacking interleukin-2 (IL-2)/IL-15 receptor beta chain are susceptible to infection with avirulent Salmonella enterica subsp. enterica serovar choleraesuis but mice lacking IL-2 are resistant.

Interleukin-2 (IL-2)/IL-15 receptor beta (IL-15R beta)(-/-) mice were susceptible to infection with avirulent Salmonella enterica subsp. enterica serovar Choleraesuis, whereas IL-2(-/-) mice were resistant. A natural killer cell response was not evident for both types of deficient mice. A Th1 response was detected in IL-2(-/-) but not in IL-2/IL-15R beta(-/-) mice infected with Salmonella, suggesting that IL-2/IL-15R beta signaling is important for the generation of protective Th1 cells.

Animals↗