| Project/Area Number |
11670273
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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 | Showa University |
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Principal Investigator |
OKUBO Sachie Showa University School of Medicine, Lecturer, 医学部, 講師 (40053938)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAGUCHI Koushi Showa University School of Medicine, Lecturer, 医学部, 講師 (70210359)
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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 |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2000: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1999: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | S.Enteritidis / catechin / EGCg / THP-1 / streptomycin / bactericidal activity / epithelial cell / macropage / Senteritidis |
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| Research Abstract |
One of the major causative agents for bacterial food poisoning is Salmanella, the pathogenicity of which is mainly caused by the cell invasive ability in the intestinal canal. Green tea extracts and catechin are known to have antibacterial action against Salmonella Enteritidis (SE). To elucidate the effects of catechin on the bacteria-host cell interaction, we investigated such a relationship using various cultured cell lines and macrophages (M φ) collected form the intraperitoneal cells of BALB/c mice.
1. Cultured cells were exposed to SE that was treated with less than the MIC of catechin (12.5-100μg/ml, epigallocatechin gallate : EGCg) for 1-2 hours. There were no differences in intracellular invation and proliferation between treated and untreated THP-1 cells (human monocyte cell line). However, the intracellular proliferation of SE was suppressed using peritoneal macrophage (resident M φ).
2. Cultured cells pretreated with catechin (25-50μg/ml) for a certain length of time were expo
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sed to SE.There was a clear increase in phagocytosis for THP-1 cells, but the intracellular proliferation of SE in these cells could not be suppressed.
3. Peritoneal macrophages from mice pre-treated with catechin (P-100 500μg/mouse×3ip) were exposed to SE.Phagocytic and bactericidal activity were observed to increase.
4. GSM 06 cell (mouse mucosal epithelial cell line) per-treated with exposed to SE.Changes in the number of intracellular viable cell counts determined by CFU were compared with those of untreated GSM 06 cells. The results showed that the intracellular invasion and proliferation of SE could not be prevented.
As a result, epithelial cells (Hep-2 and intestine 407) were pretreated with EGCg (0.5-50μg/ml) for a certain length of time and then exposed to SE for 1-2 hours. After there incubation under 5% CO, at 37℃, the cells were stained using either a Giemsa or Gram stain before being examined under a microscope ot determine intracellular invasion and proliferation. The results showed that SE invaded these cells and proliferated in the cytoplasm of many of these. The above findings suggest that catechin directly and indirectly stimulates the activation of macrophages. However, catechin did not inhibit the intracellular invation and proliferation of SE in mucosal epithelial cells, which are non-phagocytic cells.
Furthermore, the direct bactericidal activity of catechin on highly streptomycin (SM)-resistant SE (clinical isolates : MIC>50μg/ml) was weaker than that on SE-sensitive strains. Less
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