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Mechanisms for regulation of excessive host responses to LPS

Research Project

Project/Area Number 17590397
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Bacteriology (including Mycology)
Research InstitutionJichi Medical University

Principal Investigator

MATSUURA Motohiro  Jichi Medical University, School of Medicine, Associate Professor, 医学部, 助教授 (20150089)

Co-Investigator(Kenkyū-buntansha) SAITO Shinji  Jichi Medical University, School of Medicine, Instructor, 医学部, 助手 (50195989)
Project Period (FY) 2005 – 2006
Project Status Completed (Fiscal Year 2006)
Budget Amount *help
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2005: ¥1,900,000 (Direct Cost: ¥1,900,000)
Keywordslipopolysaccharide (LPS) / endotoxin / regulation of IL-12 expression / LPS antagonist
Research Abstract

Lipopolysaccharide (LPS), a cell wall component of gram-negative bacteria, is recognized by TLR4 on host immune cells to activate innate immunity leading to beneficial effects to the host. However, activation of immune reactions by LPS sometimes proceeds so strong that harmful effects are induced to the host. In the present study, regulatory mechanisms to prevent such over-activations were investigated.
Activities of LPS are expressed via actions of various mediators. IL-12 is a representative LPS-mediator and, by itself, it exhibits beneficial effects when produced properly while harmful effects when produced too much. We have found a regulatory mechanism of LPS-induced IL-12 production that activate a repressor element, GA-12, in the promoter region of IL-12p40 gene. It was indicated that hyper-activation of ERK pathway via TLR4 is required prior to activation of GA-12. When mouse peritoneal exudate cells were stimulated with a high dose LPS (1,000 ng/ml), activation of this pathway was observed and production of IL-12p40 decreased from that of optimal LPS (10 ng/ml) stimulation. These results indicated that this regulatory mechanism is functioning generally to control excessive production of IL-12.
We have also found a natural LPS-antagonist. LPS obtained from Yersinia cultured at 27℃ (optimal growth temperature) was active as LPS-agonist but LPS obtained from the bacteria cultured at 37℃ (host body temperature) was not active to human cells and showed strong antagonistic activity. Number of acyl groups in lipid A part of the LPS-37℃ was decreased from that of the LPS-27℃. This antagonistic type of the LPS-37℃ was likely to suppress all the signals downstream of TLR4 by interfering with the dimerization of TLR4.
Investigations of suppressive mechanisms in both initiation steps of LPS signaling and down stream steps for production of each LPS-mediator may be useful for development of preventive measures against harmful LPS actions.

Report

(3 results)
  • 2006 Annual Research Report   Final Research Report Summary
  • 2005 Annual Research Report
  • Research Products

    (7 results)

All 2007 2006 2005

All Journal Article (6 results) Book (1 results)

  • [Journal Article] Regulation of lipopolysaccharide-induced interleukin-12 production by activation of repressor element GA-12 through hyperactivation of the ERK patway2006

    • Author(s)
      S.Saito
    • Journal Title

      Clin. Vaccine Immunol. 13・8

      Pages: 876-883

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Regulation of lipopolysaccharide-induced interleukin-12 production by activation of repressor element GA-12 through hyperactivation of the ERK pathway2006

    • Author(s)
      S.Saito, et al.
    • Journal Title

      Clin.Vaccine Immunol. 13-8

      Pages: 876-883

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Regulation of lipopolysaccharide-induced interleukin-12 production by activation of repressor element GA-12 through hyperactivation of the ERK pathway2006

    • Author(s)
      S.Saito
    • Journal Title

      Clin. Vaccine Immunol. 13・8

      Pages: 876-883

    • Related Report
      2006 Annual Research Report
  • [Journal Article] ERK1/2経路の過剰活性化によるLPS誘導IL-12p40の抑制調節機構2005

    • Author(s)
      斎藤慎二
    • Journal Title

      第52回毒素シンポジウム予稿集 (ISSN-1344-934) 52

      Pages: 140-145

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Hyperactivation of the ERK pathway plays a role in suppressive mechanisms of LPS-induced IL-12p40 production2005

    • Author(s)
      S.Saito, et al.
    • Journal Title

      Proceedings of Toxin Symposium 52

      Pages: 140-145

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] ERK1/2経路の過剰活性化によるLPS誘導IL-12p40の抑制調節機構2005

    • Author(s)
      斎藤慎二, 松浦基博, 平井義一
    • Journal Title

      第52回毒素シンポジウム予稿集(ISSN-1334-934) 52

      Pages: 140-145

    • Related Report
      2005 Annual Research Report
  • [Book] 代謝に関する基本的概念 ブラック微生物学、第2版(林英生ら(監訳))2007

    • Author(s)
      平井義一
    • Total Pages
      32
    • Publisher
      丸善株式会社
    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary

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Published: 2005-04-01   Modified: 2016-04-21  

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