| Project/Area Number |
17590643
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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 |
Gastroenterology
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| Research Institution | Shimane University |
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Principal Investigator |
ISHIHARA Shunji Shimane University, medicine, Associate professor, 医学部, 講師 (80263531)
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| Co-Investigator(Kenkyū-buntansha) |
OSHIMA Naoki Shimane University, medicine, Student of Graduate School, Resident, 医学部, 医員 (10403461)
モハマド ルミ 島根大学, 医学部, 助手 (00379687)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Keywords | innate immunity / negative feedback system / Toll-like receptor / MyD88 / A20 / Tollip / IRAK-M / ネガティブフィードバック調整 |
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| Research Abstract |
Stimulation of Toll-like receptors (TLRs) by microbial components induces inflammatory responses, and excess and uncontrolled inflammation may lead to local tissue damage or systemic diseases. Several negative regulatory mechanisms control TLR-mediated inflammatory responses and restore the immune balance. In this study, we invested role of TLR signaling-related negative regulators including Toll-interacting protein (Tollip), IL-1-receptor-assoiated kinase (IRAK) and A20 in gut innate immune system.
For several in vitro experiments of this study, colonic epithelial cell lines, HCT-15 and HT-29 were used. Initially, TLR ligands (LPS; ligand for TLR4, flagellin; ligand for TLR5)-mediated expression of Tollip, IRAK-M and A20 in colonic epithelial cells were examined by RNase protection assay. Stimulation with TLR ligands significantly induced gene expression of Tollip, IRAK-M and A20 in HCT-15 and HT-29 cells. Next, we hypothesized that these negative regulators may be associated with development of TLR ligand-induced tolerance in colonic epithelial cells. Development of TLR ligand-induced tolerance was assessed by reporter gene assay for NF-κB and production of IL-8 in HCT-15 and HT-29 cells. NF-κB activation and production of IL-8 after restimulation with LPS as well-as flagellin were significantly decreased. To evaluate precise role of negative regulators on the development of TLR ligand-induced tolerance, we established gene knock-down systems using each vector expressing siRNA targeting for Tollip, IRAK-M and A20 gene. Down-regulation of IRAK-M expression by siRNA specific for IRAK-.M gene reinstated NF-κB activation and production of IL-8 after re-stimulation with TLR ligands. However, treatment of siRNA targeting for Tollip and A20 gene did not reinstate TLR ligand-induced tolerance. These findings suggest that IRAK-M is a key molecule to induce TLR ligand-induced tolerance and may regulate innate immune balance in gut inflammatory conditions.
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