Biomedical subjects

Osamu Takeuchi

Publications and source records attributed to Osamu Takeuchi.

80 records · Page 5Linked to original sources

PubMed2002

Human gingival CD14(+) fibroblasts primed with gamma interferon increase production of interleukin-8 in response to lipopolysaccharide through up-regulation of membrane CD14 and MyD88 mRNA expression.

Gamma interferon (IFN-gamma)-primed human gingival fibroblasts (HGF) have been shown to produce higher levels of interleukin-8 (IL-8) upon stimulation with bacterial products and inflammatory cytokines than nonprimed controls. In this study, we examined whether priming of HGF with IFN-gamma up-regulates IL-8 production by the cells in response to purified lipopolysaccharide (LPS). The priming effect of IFN-gamma was clearly observed in the high-CD14-expressing (CD14(high)) HGF but not in the low-CD14-expressing (CD14(low)) HGF. The CD14(high) HGF were most effectively primed with IFN-gamma (1,000 IU/ml) for 72 h. To elucidate the mechanism of the priming effects of IFN-gamma for the LPS response by HGF, we examined whether IFN-gamma regulated expression of CD14, Toll-like receptor 2 (TLR2), TLR4, MD-2, and MyD88, all of which are molecules suggested to be associated with LPS signaling. In CD14(high) HGF, IFN-gamma markedly up-regulated CD14 and MyD88 but not TLR4 protein and MD-2 mRNA expression, while in CD14(low) HGF, IFN-gamma slightly increased MyD88 and scarcely affected CD14, TLR4 protein, and MD-2 mRNA levels. LPS-induced IL-8 production by IFN-gamma-primed CD14(high) HGF was significantly inhibited by monoclonal antibodies (MAbs) against CD14 and TLR4, but not by an anti-TLR2 MAb. These findings suggested that IFN-gamma primed CD14(high) HGF to enhance production of IL-8 in response to LPS through augmentation of the CD14-TLR system, where the presence of membrane CD14 was indispensable for the response of HGF to LPS.

Adaptor Proteins, Signal Transducing↗

PubMed2002

Recognition of lipopeptides by Toll-like receptors.

Toll-like receptors (TLRs) recognize specific molecular patterns present only in micro-organisms and thereby activate innate immune cells. TLR2 is essential for the recognition of peptidoglycan and lipoprotein/lipopeptides. Lipoprotein/lipopeptides are observed in cell walls of a variety of micro-organisms. Host immune cells recognize the specific patterns of lipoprotein/lipopeptides through the association of TLR2 with other TLRs. TLR1 and TLR6 are highly homologous to TLR2 in structure. TLR6-deficient mice showed an impaired response to mycoplasmal lipopeptides that are diacylated, whereas TLR1-deficient mice were defective in their response to bacterial lipopeptides that are triacylated. TLR2-deficient mice did not show any inflammatory response to either type of lipopeptide. The functional association of TLR2 with TLR1 or TLR6 has been demonstrated. Thus, TLR1 and TLR6 are involved in the discrimination of a subtle difference between triacyl and diacyl lipopeptides through interaction with TLR2.

Animals↗

PubMed2002

Toxoplasma gondii-derived heat shock protein HSP70 functions as a B cell mitogen.

We have investigated the role of Toxoplasma gondii-derived heat shock protein 70 (TgHSP70) as a B cell mitogen by measuring proliferative responses in vitro. TgHSP70 induced prominent proliferative responses in murine B cells derived not only from T gondii-infected but also from uninfected mice. Nude mice responded to TgHSP70; however, severe combined immunodeficiency, RAG1-/- B6, and microMT mice failed to respond. B220+ spleen cells showed marked proliferation after stimulation with TgHSP70, but neither CD4+ nor CD8+ population responded. This unresponsiveness of CD4+ and CD8- T cells to TgHSP70 was antigen presenting cells independent. These data indicate that TgHSP70 induced the proliferation of B cells but not T cells. Polymyxin B, a potent inhibitor of lipopolysaccharide (LPS), did not eliminate TgHSP70-induced proliferation. C3H/HeN mice responded well to TgHSP70 stimulation; however, C3H/HeJ mice carrying a point mutation in the Toll-like receptor (TLR) 4 failed to respond. This indicates that TLR4 is required for TgHSP70-induced B cell activation. The involvement of TLR4 in the TgHSP70-induced proliferative responses of spleen cells was also shown by the use of TLR4-/- mice. But TgHSP70-induced, but not LPS-induced, spleen cell proliferation was observed in MyD88-/- mice, indicating that the MyD88 molecule was involved in LPS-induced proliferation but not in TgHSP70-induced proliferation.

Adaptor Proteins, Signal Transducing↗

PubMed2002

Glycosylphosphatidylinositol-anchored mucin-like glycoproteins isolated from Trypanosoma cruzi trypomastigotes induce in vivo leukocyte recruitment dependent on MCP-1 production by IFN-gamma-primed-macrophages.

Glycosylphosphatidylinositol-anchored mucin-like glycoproteins from Trypanosoma cruzi trypomastigotes (tGPI-mucins) activate macrophages in vitro to produce proinflammatory cytokines, chemokines, and nitric oxide. These effects of tGPI-mucins may be important in the ensuing immune response to T. cruzi. Here, we have sought evidence for a role of tGPI-mucins in mediating leukocyte recruitment in vivo. tGPI-mucins are highly effective in promoting cell recruitment in the pleural cavity of mice primed with IFN-gamma-inducing agents but not in naïve mice. Maximal recruitment was observed at a dose between 250 and 1250 ng tGPI-mucins. There was a significant elevation in the levels of MCP-1 in the pleural cavity of primed animals injected with tGPI-mucins, and in vivo neutralization of MCP-1 abolished leukocyte recruitment. Pretreatment with anti-MIP-1alpha or anti-RANTES had no effect on the recruitment induced by tGPI-mucins. MCP-1 immunoreactivity was detected in pleural macrophages, and macrophages produced MCP-1 in vitro, especially after priming with IFN-gamma. Finally, tGPI-mucins induced significant leukocyte recruitment in primed C3H/HeJ but not in TLR2-deficient mice. Together, our results suggest that T. cruzi-derived GPI-mucins in conjunction with IFN-gamma may drive tissue chemokine production and inflammation and bear a significant role in the pathogenesis of Chagas disease.

Animals↗

PubMed2001

Recombinant human interleukin-11 improved carboplatin-induced thrombocytopenia without affecting antitumor activities in mice bearing Lewis lung carcinoma cells.

PURPOSE: Interleukin-11 (IL-11) is a stromal cell derived multifunctional cytokine, which plays important roles in the hematopoietic and nonhematopoietic systems. Recombinant human IL-11 (rhIL-11) is used in the treatment of chemotherapy-induced thrombocytopenia. We have investigated the effects of rhIL-11 on the antitumor activity of chemotherapeutic agents and on thrombocytopenia in myelosuppressed mice bearing tumor cells. METHODS: We tested the effect of rhIL-11 on Lewis lung carcinoma (LLC) cell proliferation when used alone or in combination with three antitumor agents in vitro. Also, a newly developed chemotherapy-induced myelosuppressed mice model bearing LLC cells was used to study the effects of rhIL-11 on the antitumor activity and on thrombocytopenia. RESULTS: On its own, rhIL-11 (1-100 ng/ml) did not stimulate cell proliferation, and did not alter the antitumor activities of carboplatin, mitomycin C, or etoposide in vitro. In mice implanted with LLC cells (1 x 10(4)), carboplatin (50 mg/kg/day for 2 consecutive days, i.p.) inhibited tumor growth and caused thrombocytopenia. Treatment with rhIL-11 (500 microg/kg/day, from the day following the last dosing with carboplatin for 14 days, s.c.) successfully prevented thrombocytopenia without affecting the antitumor activity of carboplatin. With rhIL-11 there was no obvious effect on the red blood cell count, white blood cell count, or body weight. CONCLUSION: These results support the assertion that rhIL-11 may be a significant therapeutic agent for thrombocytopenia following cancer chemotherapy, and that it need be associated with little fear of tumor proliferation.

Animals↗

PubMedDate not supplied

Hepatic resection under in situ hypothermic hepatic perfusion.

BACKGROUND/AIMS: Temporary inflow occlusion of the portal triad has been used frequently in hepatectomy to minimize bleeding. On the other hand, Pringle's maneuver produces ischemic-reperfusion injury especially in patients with underlying liver disease. METHODOLOGY: Thirty-seven cases of hepatic resections were performed with intermittent Pringle's maneuver (IP group; n = 17) and in situ hypothermic perfusion (CP group; n = 20). In the CP group, hepatic inflow was continuously occluded, and 4-degree Centigrade Ringer's lactate was administered by drip during resection. Hepatic outflow occlusion was not performed. RESULTS: All patients tolerated the procedures well. Cold perfusion technique significantly decreased both the times required and the blood loss in hepatectomy (p < 0.05). Serum hyaluronic acid levels gradually increased after the induction of hepatectomy and peaked 10 minutes after reperfusion in the both groups. Thereafter, it decreased and showed a significantly lower level in the CP group until 60 minutes after reperfusion (p < 0.05). Hepaplastin levels remained significantly higher in the CP group one week after operation (p < 0.05). CONCLUSIONS: Using the technique of in situ hypothermic perfusion, we can prolong the ischemic time safely with minimal systemic influence even in cases with underlying liver diseases. This may compare favorably with intermittent Pringle's maneuver in terms of reducing hepatic sinusoidal endothelial cell damage during hepatectomy and reperfusion.

Adult↗

PubMedDate not supplied

Effect of the herbal medicine Dai-kenchu-to for serum ammonia in hepatectomized patients.

BACKGROUND/AIMS: Prolonged paralytic ileus occurring in hepatectomized patients may induce hyperammonemia or bacterial translocation, which injures the remnant liver function and sometimes causes post-resection liver failure. We examined the effectiveness of the herbal medicine, Dai-kenchu-to (DKT), on postoperative serum ammonia levels in patients with liver resection and compared it with lactulose. METHODOLOGY: Patients with liver resection were divided into three groups. Lactulose group (n=31), 16g of lactulose was administered orally three times a day from the first postoperative day. DKT group (n=27), 5g of DKT was administered in the same fashion. Control group (n=26), neither lactulose nor DKT was administered. In all three groups, 16g of lactulose was administered three times a day for three days preoperatively. RESULTS: There was no significant difference among the groups in age, gender and preoperative hepatic functional values, such as ICG-R15 or galactose tolerance test. There was also no difference in parenchymal hepatic resection rate, operative time and amount of intraoperative bleeding volume. Postoperative serum ammonia levels were significantly lower in the DKT group than control and lactulose groups. Instances of delayed flatulence and occurrence of diarrhea were also fewer in the DKT group. CONCLUSIONS: DKT may become a more effective and safe agent than lactulose in postoperative management of liver resection.

Aged↗

PubMedDate not supplied

A case of small cell carcinoma of the common bile duct.

Small cell carcinoma occasionally occurs in the gastrointestinal tract, but rarely in the biliary tract. We report a case of small cell carcinoma which occurred in the common bile duct. A 66-year-old female complained of epigastralgia and weight loss. Computed tomography and ultrasonography showed a mass near the pancreas head and dilatation of the intrahepatic bile ducts. Endoscopic nasobiliary drainage was undertaken, and it revealed obstruction of the common bile duct. The patient was diagnosed preoperatively as having extrahepatic bile duct cancer. Upon laparotomy, a tumor was found to be located in the middle common bile duct. Pylorus-preserving pancreaticoduodenectomy was performed. The main trunk of the portal vein and the right hepatic artery were resected concomitantly because of tumor involvement. Postoperative pathological examination revealed well-differentiated papillary adenocarcinoma on the surface of the bile duct lumen, but a large part of the extraductal component was small cell carcinoma. Upon immunohistochemical examination, synaptophysin and chromogranin A were found to be focally positive in small cell carcinoma, but negative for L-26 and CEA. The patient then underwent two postoperative courses of systemic chemotherapy. Nevertheless, she died of cancer recurrence eight months after the operation, which showed that the tumor had a highly lethal nature, with rapid and widespread dissemination. Further therapeutic trials are needed to improve survival in such cases.

Aged↗