| Project/Area Number |
11670283
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Bacteriology (including Mycology)
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| Research Institution | NATIONAL INSTITUTE OF HEALTH SCIENCES |
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Principal Investigator |
TANAMOTO Ken-ichi National Institute of Health Sciences, Bacteriology, Head, 衛生微生物部, 部長 (60107430)
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| Co-Investigator(Kenkyū-buntansha) |
MUROI Masasi National Institute of Health Sciences, Bacteriology,, 衛生微生物部, 室長 (70311389)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2000: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1999: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | endotoxin / lipid A / CD14 / species specificity / Toll-like receptors / MD-2 / Salmonella lipid A |
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| Research Abstract |
The stimulation of both THP-1 and U937 human-derived cells by Salmonella lipid A preparations from various strains as well as hexaacylated lipid A (506) and Salmonella-type hepataacylated lipid A (516), as assessed by TNF-α induction and NF-κB activation, was found to be inactive compared to Escherichia coli lipid A, but all of the lipid As exerted strongactivity on mouse cells and on Limulus gelation activity. Both lipid A preparations strongly induced TNF-α release and activated NF-κB in mouse peritoneal macrophages and mouse macrophage-like cell line J7741 and induced Limulus gelation activity. In addition, both 516 and lipid A from Salmonella were found to antagonize the 506 and E.coli, LPS action that induced TNF-α release and NF-κB activation in THP-1 cells. The mechanism of the species specificity exhibited by Salmonslla lipid A was elucidated on molecular basis. Salmonella lipid A was revealed to act as an agonist on human macrophages when mouse (m)TLR2 and mMD-2 was transfecte
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d. However, when the mMD-2 was replaced with human (h)MD-2 in the same experiment, the activity reduced drastically. The results show that MD-2 plays a predominant role for the species specificity of Salmonella lipid A.In the course of the study we also found that lipid A preparations from E.coli Salmonella abortus equi and Salmonella minnesota failed to activate NF-κB-dependent luciferase activity in 293 cells transiently expressing TLR2 and CD14, although all of these preparations strongly induced the degradation of IκB- NF-κB α in a mouse macrophage cell line J7741. Both of synthetic lipid A compounds, 506 and 516, also failed to activate NF-κB-dependent luciferase activity and to induce the translocation of NF-κB p65 subunit into nuclei in 293 cells transiently as well as stably expressing TLR2 and CD14 of both human or mouse origin. These results indicate that TLR2/CD14 complex does not recognize E.coli and Salmonella lipid A molecules and support the notion that TLR2 is not an essential molecule for endotoxin signaling. Less
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