Biomedical subjects

Kiyoshi Takeda

Publications and source records attributed to Kiyoshi Takeda.

At least 109 records · Page 6Linked to original sources

PubMed2003

Immunogenicity of Peptide-25 of Ag85B in Th1 development: role of IFN-gamma.

Ag85B (also known as alpha antigen or MPT59) is immunogenic, and induces expansion and differentiation of TCRVbeta11(+)CD4(+) T cells to IFN-gamma-producing cells in C57BL/6 (I-A(b)) mice. We reported that Peptide-25 (amino acids 240-254) of Ag85B is a major T cell epitope, and its amino acid residues at position 244, 247, 249 and 252 are I-A(b) contact residues. Here we examined roles of IFN-gamma in the generation of Peptide-25-reactive CD4(+) TCRVbeta11(+) T cells and the efficacy of mutant peptides of Peptide-25 for T(h)1 development in mice other than C57BL/6 mice. Immunization of C57BL/6 mice with Peptide-25 included in incomplete Freund's adjuvant led to preferential induction of CD4(+) TCRVbeta11(+) IFN-gamma- and tumor necrosis factor-alpha-producing T cells. Compared with other I-A(b)-binding peptides such as Peptide-9 of Ag85B, 50V of pigeon cytochrome c and ovalbumin (OVA)(265-280) peptide, only Peptide-25 was capable of inducing enormous expansion of TCRVbeta11(+) IFN-gamma-producing T cells. Treatment of C57BL/6 mice with anti-Vbeta11 antibody before Peptide-25 immunization reduced the development of CD4(+) IFN-gamma-producing T cells. Furthermore, B10.A(3R) mice, I-A(b)-positive and TCRVbeta11(-) strain, showed remarkably lower response to Peptide-25 immunization than C57BL/6 mice. Peptide-25-primed IFN-gamma(-/-) cells showed significantly decreased expansion of CD4(+) TCRVbeta11(+) T cells as compared with wild-type cells. Interestingly, Peptide-25-primed cells from MyD88-deficient mice responded to Peptide-25 and differentiated into IFN-gamma-producing cells to a similar extent as wild-type mice, indicating Toll-like receptor-independent IFN-gamma production. These results imply that IFN-gamma plays important roles for the generation and expansion of CD4(+) TCRVbeta11(+) T cells in response to Peptide-25. Although Peptide-25 was non-immunogenic in C3H/HeN mice, a substituted mutant of Peptide-25, 244D247V, capable of binding to I-A(k), induced T(h)1 development. These results clearly demonstrate important roles of IFN-gamma in the expansion of CD4(+) TCRVbeta11(+) T cells, and will provide useful information for delineating the regulatory mechanisms of T(h)1-cell development and for analyzing mechanisms on T(h)1-dominant immune responses.

Amino Acid Sequence↗

PubMed2003

No role for interleukin-18 in acute murine stroke-induced brain injury.

There is now extensive evidence to show that the cytokine interleukin-1 (IL-1) contributes directly to reversible and permanent ischemic brain damage in rodents. Because interleukin-18 (IL-18) shares many structural and functional similarities with IL-1, the authors tested the hypothesis that IL-18 contributes directly to ischemic brain damage in mice exposed to focal, reversible (15-minute or 30-minute) middle cerebral artery occlusion. IL-18 expression was not induced acutely by middle cerebral artery occlusion, and deletion of the IL-18 gene (IL-18 knockout mice) did not affect infarct volume. The present results suggest that IL-18 does not contribute to acute ischemic brain damage.

Acute Disease↗

PubMed2003

Mycobacterial infection in MyD88-deficient mice.

MyD88 is an adaptor protein that plays a major role in TLR/IL-1 receptor family signaling. To understand the role of MyD88 in the development of murine tuberculosis in vivo, MyD88 knockout (KO) mice aerially were infected with Mycobacterium tuberculosis. Infected MyD88 mice were not highly susceptible to M. tuberculosis infection, but they developed granulomatous pulmonary lesions with neutrophil infiltration which were larger than those in wild-type (WT) mice (P < 0.01). The pulmonary tissue levels of mRNA for iNOS and IL-18 were slightly lower, but levels of mRNA for IL-1 beta, IL-2, IL-4, IL-6, IL-10, IFN-gamma, and TGF-beta were higher in MyD88 KO mice. IFN-gamma, TNF-alpha, IL-1 beta, and IL-12 also were high in the sera of MyD88 KO mice. There were no statistically significant differences in the expression of TNF-alpha, IL-12, and ICAM-1 mRNA between MyD88 KO and WT mice. Thus, MyD88 deficiency did not influence the development of murine tuberculosis. NF-kappa B activity was similar in the alveolar macrophages from the lung tissues of MyD88 KO and WT mice. Also, there may be a TLR2-specific, MyD88-independent IL-1 receptor/TLR-mediated pathway to activate NF-kappa B in the host defense against mycobacterial infection.

Adaptor Proteins, Signal Transducing↗

PubMed2003

Interleukin-18 facilitates the early antimicrobial host response to Escherichia coli peritonitis.

To determine the role of endogenous interleukin-18 (IL-18) during peritonitis, IL-18 gene-deficient (IL-18 KO) mice and wild-type mice were intraperitoneally (i.p.) infected with Escherichia coli, the most common causative agent found in septic peritonitis. Peritonitis was associated with a bacterial dose-dependent increase in IL-18 concentrations in peritoneal fluid and plasma. After infection, IL-18 KO mice had significantly more bacteria in the peritoneal lavage fluid and were more susceptible for progression to systemic infection at 6 and 20 h postinoculation than wild-type mice. The relative inability of IL-18 KO mice to clear E. coli from the abdominal cavity was not due to an intrinsic defect in the phagocytosing capacity of their peritoneal macrophages or neutrophils. IL-18 KO mice displayed an increased neutrophil influx into the peritoneal cavity, but these migratory neutrophils were less activate, as reflected by a reduced CD11b surface expression. These data suggest that endogenous IL-18 plays an important role in the early antibacterial host response during E. coli-induced peritonitis.

Animals↗

PubMed2003

Interleukin-18 impairs the pulmonary host response to Pseudomonas aeruginosa.

Interleukin-18 (IL-18) is a potent cytokine with many different proinflammatory activities. To study the role of IL-18 in the pathogenesis of Pseudomonas pneumonia, IL-18-deficient (IL-18(-/-)) and wild-type mice were intranasally inoculated with Pseudomonas aeruginosa. IL-18 deficiency was associated with reduced outgrowth of Pseudomonas in the lungs and diminished dissemination of the infection. In addition, pulmonary inflammation (histopathology) and levels of tumor necrosis factor alpha, IL-6, and macrophage inflammatory protein-2 in lungs and plasma were lower in IL-18(-/-) mice. Consistent with results obtained for IL-18(-/-) mice, treatment of wild-type mice with a neutralizing IL-18 binding protein-immunoglobulin G Fc fusion construct also attenuated outgrowth of Pseudomonas compared with that for mice treated with a control protein. These results demonstrate that the presence of endogenous IL-18 activity facilitates inflammatory responses in the lung during Pseudomonas pneumonia, concurrently impairing bacterial clearance.

Animals↗

PubMed2003

TAB2 is essential for prevention of apoptosis in fetal liver but not for interleukin-1 signaling.

The proinflammatory cytokine interleukin-1 (IL-1) transmits a signal via several critical cytoplasmic proteins such as MyD88, IRAKs and TRAF6. Recently, serine/threonine kinase TAK1 and TAK1 binding protein 1 and 2 (TAB1/2) have been identified as molecules involved in IL-1-induced TRAF6-mediated activation of AP-1 and NF-kappa B via mitogen-activated protein (MAP) kinases and I kappa B kinases, respectively. However, their physiological functions remain to be clarified. To elucidate their roles in vivo, we generated TAB2-deficient mice. The TAB2 deficiency was embryonic lethal due to liver degeneration and apoptosis. This phenotype was similar to that of NF-kappa B p65-, IKK beta-, and NEMO/IKK gamma-deficient mice. However, the IL-1-induced activation of NF-kappa B and MAP kinases was not impaired in TAB2-deficient embryonic fibroblasts. These findings demonstrate that TAB2 is essential for embryonic development through prevention of liver apoptosis but not for the IL-1 receptor-mediated signaling pathway.

Adaptor Proteins, Signal Transducing↗

PubMed2003

Toll-like receptor-dependent production of IL-12p40 causes chronic enterocolitis in myeloid cell-specific Stat3-deficient mice.

Stat3 plays an essential role in IL-10 signaling pathways. A myeloid cell-specific deletion of Stat3 resulted in inflammatory cytokine production and development of chronic enterocolitis with enhanced Th1 responses in mice. In this study, we analyzed the mechanism by which a Stat3 deficiency in myeloid cells led to the induction of chronic enterocolitis in vivo. Even in the absence of Stat1, which is essential for IFN-gamma signaling pathways, Stat3 mutant mice developed chronic enterocolitis. TNF-alpha/Stat3 double-mutant mice developed severe chronic enterocolitis with enhanced Th1 cell development. IL-12p40/Stat3 double-mutant mice, however, showed normal Th1 responses and no inflammatory change in the colon. RAG2/Stat3 double-mutant mice did not develop enterocolitis, either. These findings indicate that overproduction of IL-12p40, which induces potent Th1 responses, is essential for the development of chronic enterocolitis in Stat3 mutant mice. Furthermore, enterocolitis was significantly improved and IFN-gamma production by T cells was reduced in TLR4/Stat3 double-mutant mice, indicating that TLR4-mediated recognition of microbial components triggers aberrant IL-12p40 production by myeloid cells, leading to the development of enterocolitis. Thus, this study clearly established a sequential innate and acquired immune mechanism for the development of Th1-dependent enterocolitis.

Animals↗

PubMed2003

Stat3 protects against Fas-induced liver injury by redox-dependent and -independent mechanisms.

Signal transducer and activator of transcription-3 (Stat3) is one of the most important molecules involved in the initiation of liver development and regeneration. In order to investigate the hepatoprotective effects of Stat3, we examined whether Stat3 protects against Fas-mediated liver injury in the mouse. A constitutively activated form of Stat3 (Stat3-C) was adenovirally overexpressed in mouse liver by intravenous injection, and then a nonlethal dose of Fas agonist (Jo2) was injected intraperitoneally into the mouse (0.3 microg/g body wt). Stat3-C dramatically suppressed both apoptosis and necrosis induced by Jo2. In contrast, liver-specific Stat3-knockout mice failed to survive following Jo2 injection. Stat3-C upregulated expression of FLICE inhibitor protein (FLIP), Bcl-xL, and Bcl-2, and accordingly downregulated activities of FLICE and caspase-3 that were redox-independent. Interestingly, Stat3-C also upregulated the redox-associated protein redox factor-1 (Ref-1) and reduced apoptosis in liver following Jo2 injection by suppressing oxidative stress and redox-sensitive caspase-3 activity. These findings indicate that Stat3 activation protects against Fas-mediated liver injury by inhibiting caspase activities in redox-dependent and -independent mechanisms.

Animals↗

PubMed2003

A small preoperative test dose of intravenous fentanyl can predict subsequent analgesic efficacy and incidence of side effects in patients due to receive epidural fentanyl.

UNLABELLED: Because individual variation is a likely factor affecting both the incidence and severity of side effects and the analgesic efficacy of epidural opioids, assessment of individual variation could be useful in deciding optimal dosage. By evaluating the response to a small test dose of IV fentanyl, we designed this study to predict the degree of pain relief and the incidence of side effects in patients who would be receiving postoperative epidural fentanyl. Before the induction of anesthesia, 50 micro g of fentanyl was administered IV, and 2 min after fentanyl, the patient response was evaluated. Twenty-three patients, who reported nausea, sleepiness, dizziness, sensation of warmth, and other symptoms, were categorized as responders (Group R); the remaining 20 patients were categorized as nonresponders (Group NR). At the completion of surgery, infusion of epidural fentanyl was administered (0.3 mg/d in 0.25% bupivacaine) for 96 h. At postoperative Hours 6 and 24, Group R had significantly lower visual analog scale scores for postoperative pain intensity and required fewer analgesics than Group NR. The incidence of side effects, however, was 74% for Group R and 10% for Group NR (P < 0.05), and side effects were more serious in Group R. This study demonstrates that preoperative administration of a small dose of fentanyl during the induction of anesthesia enables prediction of the analgesic efficacy of postoperative epidural fentanyl and the incidence and severity of side effects. IMPLICATIONS: Preoperative administration of a small dose of fentanyl during the induction of anesthesia enables prediction of the analgesic efficacy of postoperative epidural fentanyl and the incidence and severity of side effects.

Aged↗

PubMed2003

Characteristics of an anaerobic, syntrophic, butyrate-degrading bacterium in paddy field soil.

The number of syntrophic butyrate-degrading bacteria in a flooded paddy field soil was 1.7 x 10(3) MPN/g dry soil. Butyrate was degraded to acetate and methane when paddy soils were incubated anaerobically with the addition of butyrate. However, butyrate degradation was completely suppressed by the addition of the specific inhibitor of methanogenesis, 2-bromoethanesulfonate (BES) to the soil. A hydrogen-using methanogen, strain TM-8, was isolated from flooded paddy field soil. Strain TM-8 was identified as Methanobacterium formicicum based on its physiology and phylogeny. Syntrophic butyrate-degrading bacteria were enumerated and isolated using strain TM-8. A syntrophic butyrate-degrading bacterium, strain TB-6, was isolated in coculture with strain TM-8 from paddy soil. The strain was Gram-negative, had curved rods, and grew on crotonate. Sulfate was not used as an electron acceptor. Strain TB-6 was closely related to S. wolfei subsp. wolfei. The relation between strain TB-6 and the members of Syntrophomonas are discussed.

Bacteria, Anaerobic↗

PubMed2002

Cutting edge: a novel Toll/IL-1 receptor domain-containing adapter that preferentially activates the IFN-beta promoter in the Toll-like receptor signaling.

MyD88 is a Toll/IL-1 receptor (TIR) domain-containing adapter common to signaling pathways via Toll-like receptor (TLR) family. However, accumulating evidence demonstrates the existence of a MyD88-independent pathway, which may explain unique biological responses of individual TLRs, particularly TLR3 and TLR4. TIR domain-containing adapter protein (TIRAP)/MyD88 adapter-like, a second adapter harboring the TIR domain, is essential for MyD88-dependent TLR2 and TLR4 signaling pathways, but not for MyD88-independent pathways. Here, we identified a novel TIR domain-containing molecule, named TIR domain-containing adapter inducing IFN-beta (TRIF). As is the case in MyD88 and TIRAP, overexpression of TRIF activated the NF-kappaB-dependent promoter. A dominant-negative form of TRIF inhibited TLR2-, TLR4-, and TLR7-dependent NF-kappaB activation. Furthermore, TRIF, but neither MyD88 nor TIRAP, activated the IFN-beta promoter. Dominant-negative TRIF inhibited TLR3-dependent activation of both the NF-kappaB-dependent and IFN-beta promoters. TRIF associated with TLR3 and IFN regulatory factor 3. These findings suggest that TRIF is involved in the TLR signaling, particularly in the MyD88-independent pathway.

Adaptor Proteins, Vesicular Transport↗

PubMed2002

Essential role for TIRAP in activation of the signalling cascade shared by TLR2 and TLR4.

Signal transduction through Toll-like receptors (TLRs) originates from their intracellular Toll/interleukin-1 receptor (TIR) domain, which binds to MyD88, a common adaptor protein containing a TIR domain. Although cytokine production is completely abolished in MyD88-deficient mice, some responses to lipopolysaccharide (LPS), including the induction of interferon-inducible genes and the maturation of dendritic cells, are still observed. Another adaptor, TIRAP (also known as Mal), has been cloned as a molecule that specifically associates with TLR4 and thus may be responsible for the MyD88-independent response. Here we report that LPS-induced splenocyte proliferation and cytokine production are abolished in mice lacking TIRAP. As in MyD88-deficient mice, LPS activation of the nuclear factor NF-kappaB and mitogen-activated protein kinases is induced with delayed kinetics in TIRAP-deficient mice. Expression of interferon-inducible genes and the maturation of dendritic cells is observed in these mice; they also show defective response to TLR2 ligands, but not to stimuli that activate TLR3, TLR7 or TLR9. In contrast to previous suggestions, our results show that TIRAP is not specific to TLR4 signalling and does not participate in the MyD88-independent pathway. Instead, TIRAP has a crucial role in the MyD88-dependent signalling pathway shared by TLR2 and TLR4.

Adaptor Proteins, Signal Transducing↗

PubMed2002

Negative regulation of platelet clearance and of the macrophage phagocytic response by the transmembrane glycoprotein SHPS-1.

SHPS-1 is a receptor-type glycoprotein that binds and activates the protein-tyrosine phosphatases SHP-1 and SHP-2, and thereby negatively modulates intracellular signaling initiated by various cell surface receptors coupled to tyrosine kinases. SHPS-1 also regulates intercellular communication in the neural and immune systems through its association with CD47 (integrin-associated protein) on adjacent cells. Furthermore, recent studies with fibroblasts derived from mice expressing an SHPS-1 mutant that lacks most of the cytoplasmic region suggested that the intact protein contributes to cytoskeletal function. Mice homozygous for this SHPS-1 mutation have now been shown to manifest thrombocytopenia. These animals did not exhibit a defect in megakaryocytopoiesis or in platelet production. However, platelets were cleared from the bloodstream more rapidly in the mutant mice than in wild-type animals. Furthermore, peritoneal macrophages from the mutant mice phagocytosed red blood cells more effectively than did those from wild-type mice; in addition, they exhibited an increase both in the rate of cell spreading and in the formation of filopodia-like structures at the cell periphery. These results indicate that SHPS-1 both contributes to the survival of circulating platelets and down-regulates the macrophage phagocytic response.

Animals↗

PubMed2002

IL-18 contributes to the spontaneous development of atopic dermatitis-like inflammatory skin lesion independently of IgE/stat6 under specific pathogen-free conditions.

Atopic dermatitis (AD) is a pruritic inflammatory skin disease. Because IL-18 directly stimulates T cells and mast cells to release AD-associated molecules, Th2 cytokines, and histamine, we investigated the capacity of IL-18 to induce AD-like inflammatory skin disease by analyzing KIL-18Tg and KCASP1Tg, which skin-specifically overexpress IL-18 and caspase-1, respectively. They spontaneously developed relapsing dermatitis with mastocytosis and Th2 cytokine accumulation accompanied by systemic elevation of IgE and histamine. Stat6-deficient KCASP1Tg displayed undetectable levels of IgE but manifested the same degree of cutaneous changes, whereas IL-18-deficient KCASP1Tg evaded the dermatitis, suggesting that IL-18 causes the skin changes in the absence of IgE/stat6. KIL-18Tg and IL-1-deficient KCASP1Tg took longer to display the lesion than KCASP1Tg. Thus, AD-like inflammation is initiated by overrelease of IL-18 and accelerated by IL-1. Our present study might provide insight into understanding the pathogenesis of and establishing therapeutics for chronic inflammatory skin diseases including AD.

Animals↗

PubMed2002

Rapid chromatin remodeling of Toll-like receptor 2 promoter during infection of macrophages with Mycobacterium avium.

We have previously reported that NF-kappa B and stimulating factor 1 elements within the proximal mouse Toll-like receptor 2 (TLR2) promoter region are required for the transcriptional activation of TLR2 expression following infection with Mycobacterium avium. In the present study, we found that a rapid increase in both DNase I sensitivity and restriction enzyme accessibility at the TLR2 promoter region occurred following infection with M. avium. Increase in restriction enzyme accessibility at the TLR2 promoter region covering the NF-kappa B and stimulating factor 1 elements was associated with the induction of TLR2 expression at the mRNA level. Furthermore, the increase in restriction enzyme accessibility at the TLR2 promoter region did not appear to result from binding of NF-kappa B, but rather depended on a TLR2-myeloid differentiation factor 88 signaling pathway. Together our results indicate that chromatin remodeling occurs at TLR2 promoter region following infection with M. avium, allowing the access of transcription factors to initiate the transcription of TLR2.

Adaptor Proteins, Signal Transducing↗

PubMed2002

Proteolytic processing of Stat6 signaling in mast cells as a negative regulatory mechanism.

Accumulating evidence has shown the importance of Stat6-mediated signaling in allergic diseases. In this study, we show a novel regulatory mechanism of Stat6-mediated signaling in mast cells. When Stat6 is activated by interleukin (IL)-4 and translocated to the nucleus, Stat6 is cleaved by a nucleus-associated protease in mast cells. The cleaved 65-kD Stat6 lacks the COOH-terminal transactivation domain and functions as a dominant-negative molecule to Stat6-mediated transcription. The retrovirus-mediated expression of cleavage-resistant Stat6 mutants prolongs the nuclear accumulation of Stat6 upon IL-4 stimulation and enhances IL-4-induced gene expression and growth inhibition in mast cells. These results indicate that the proteolytic processing of Stat6 functions as a lineage-specific negative regulator of Stat6-dependent signaling in mast cells, and thus suggest that it may account for the limited role of Stat6 in IL-4 signaling in mast cells.

Animals↗

PubMed2002

Cutting edge: role of Toll-like receptor 1 in mediating immune response to microbial lipoproteins.

The Toll-like receptor (TLR) family acts as pattern recognition receptors for pathogen-specific molecular patterns (PAMPs). TLR2 is essential for the signaling of a variety of PAMPs, including bacterial lipoprotein/lipopeptides, peptidoglycan, and GPI anchors. TLR6 associates with TLR2 and recognizes diacylated mycoplasmal lipopeptide along with TLR2. We report here that TLR1 associates with TLR2 and recognizes the native mycobacterial 19-kDa lipoprotein along with TLR2. Macrophages from TLR1-deficient (TLR1(-/-)) mice showed impaired proinflammatory cytokine production in response to the 19-kDa lipoprotein and a synthetic triacylated lipopeptide. In contrast, TLR1(-/-) cells responded normally to diacylated lipopeptide. TLR1 interacts with TLR2 and coexpression of TLR1 and TLR2 enhanced the NF-kappaB activation in response to a synthetic lipopeptide. Furthermore, lipoprotein analogs whose acylation was modified were preferentially recognized by TLR1. Taken together, TLR1 interacts with TLR2 to recognize the lipid configuration of the native mycobacterial lipoprotein as well as several triacylated lipopeptides.

Acylation↗

PubMed2002

Contribution of IL-18 to Th1 response and host defense against infection by Mycobacterium tuberculosis: a comparative study with IL-12p40.

The present study was conducted to critically determine the protective role of IL-18 in host response to Mycobacterium tuberculosis infection. IL-18-deficient (knockout (KO)) mice were slightly more prone to this infection than wild-type (WT) mice. Sensitivity of IL-12p40KO mice was lower than that of IL-12p40/IL-18 double KO mice. IFN-gamma production caused by the infection was significantly attenuated in IL-18KO mice compared with WT mice, as indicated by reduction in the levels of this cytokine in sera, spleen, lung, and liver, and its synthesis by spleen cells restimulated with purified protein derivatives. Serum IL-12p40 level postinfection and its production by peritoneal exudate cells stimulated with live bacilli were also significantly lower in IL-18KO mice than WT mice, suggesting that attenuated production of IFN-gamma was secondary to reduction of IL-12 synthesis. However, this was not likely the case, because administration of excess IL-12 did not restore the reduced IFN-gamma production in IL-18KO mice. In further studies, IL-18 transgenic mice were more resistant to the infection than control littermate mice, and serum IFN-gamma level and its production by restimulated spleen cells were increased in the former mice. Taken together, our results indicate that IL-18 plays an important role in Th1 response and host defense against M. tuberculosis infection although the contribution was not as profound as that of IL-12p40.

Animals↗