2004 Fiscal Year Final Research Report Summary
Essential role of MD-2 in TLR4-dependent signaling during Helicobacter pylori- associated gastritis
| Project/Area Number |
15590647
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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 (2004)
Shimane Medical University (2003) |
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Principal Investigator |
ISHIHARA Shunji Shimane University, School of Medicine, Senior Assistant Professor, 医学部, 講師 (80263531)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIKAZU Kinoshita Shimane University, School of Medicine, Professor, 医学部, 教授 (30243306)
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| Project Period (FY) |
2003 – 2004
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| Keywords | H.pylori / Innate immunity / Toll-like receptor 4 / MD-2 |
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| Research Abstract |
Toll-like receptor 4(TLR4), a member of pattern recognition receptors, is the main receptor of lipopolysaccharide(LPS). MD-2 physically associates with TLR4 on the cell surface and confers LPS responsiveness. H.pylori LPS is one of the major virulence factors for induction of gastritis. We demonstrated here the role of MD-2 in TLR4-dependent signaling in H.pylori-associated gastritis. Gastric biopsy samples collected from patients with and without H.pylori infection and 4 gastric cancer cell lines were used for this study. TLR-4 and MD-2 expression in biopsy specimens and the cell lines was examined by using RT-PCR. Localization of TLR-4 in histological sections was evaluated by immunohistochemistry. For in vitro functional assays, we established stable transfectants of AGS cells expressing TLR4 and MD-2. Cellular distribution of TLR4 was examined by flow cytometry. NF-κB activation and activation of IL-8 and MD-2 promoters were assessed by reporter gene assay. H.pylori infection up-regulated the TLR4 and MD-2 expression in gastric mucosa. TLR4 staining was observed predominantly in epithelial cells, located in both the cytoplasm and at the apical surface. MD-2 transfection in AGS cells markedly increased cell surface expression of TLR4 and augmented the activation of NF-κB and IL-8 promoter upon stimulation with H.pylori LPS. Live H.pylori also stimulated transcriptional activation of MD-2. This study revealed that MD-2 expression is elevated in gastric epithelial cells during H.pylori infection, suggesting that the TLR4/MD-2 system is a potent receptor complex involved in the response to H.pylori LPS in the stomach.
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Research Products
(18 results)
