| Budget Amount *help |
¥6,400,000 (Direct Cost: ¥6,400,000)
Fiscal Year 2002: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2001: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Research Abstract |
Green tea polyphenol blocks H_2O_2-induced IL-8 production and mRNA expression from A549 cells: Production of IL-8 from A549 cells was increased by H_2O_2-stimulation in a dose-dependent manner during 6 h of incubation period. Cells were pre-treated with various concentrations of polyphenol (0-0.2 mg/ml) for 2 h and then challenged with H_2O_2 (400 μM) for 1 h, 3 h, or 6 h in the presence of polyphenol, which reduced IL-8 production in a time- and dose-dependent fashion, with the maximal inhibition at 6 h as 76.1 %. H_2O_2 also increased IL-8 mRNA expression, which was also reduced by polyphenol pre-treatment at each time point we studied. However, when green tea polyphenol was added together with H_2O_2 for 6 h, the maximal inhibitory effect on IL-8 release was only 43.0 %. Green tea polyphenol (0.05-0.2mg/ml) and H_2O_2 (400μM) did not affect the viability of A549 cells.
Scavenging action against H_2O_2 by Green tea polyphenol: We measured the concentration of H_2O_2 in the cell-free medium after incubation of H_2O_2 (400μM) with various concentrations of polyphenol, which reduced H_2O_2 in a dose-dependent manner with the maximal reduction of 39.0 %.
Green tea polyphenol blocks H_2O_2-induced JNK and p38 activation in A549 cells: To investigate the mechanism of the inhibition of H_2O_2-induced IL-8 production in A549 cells by green tea polyphenol, we studied the effect of green tea polyphenol on H_2O_2-induced activation of three MAP kinases, JNK, p38 and p44/42. Green tea polyphenol inhibited phosphorylation of JNK and p38 at each time point. However, p44/42 was phosphorylated under control condition, and H_2O_2 stimulation increased p44/42 phosphorylation, but green tea polyphenol did not affect the phosphorylation of p44/42.
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