| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2003: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2002: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
We determined the role of EGFR in pathogenesis of asthma both in vivo and in vitro. Brown Norway rats were sensitized (day 0, day 7) and challenged (days 14, 15 and 16) with ovalbumin (OVA). Morphological analysis (Alcian blue/PAS staining, immunohistochemistry for MUC5AC and EGFR), measurement of airway hyperreactivity (penH) and cell analysis (BAL) were performed on days 14 (before OVA challenge), 17, 24, 31 and day 38. On day 17, OVA-sensitized and challenged rats showed a marked increase in both MUC5AC and EGFR immunoreactivity in airway epithelium. Without additional OVA challenge, spontaneous resolution of both inflammatory cell infiltration and goblet cell hyperplasia were observed simultaneously with the reduction of EGFR expression on day 38. In contrast, AHR persisted for three weeks. Intratracheal instillation of the selective EGFR tyrosine kinase inhibitor AG1478 induced a significant reduction in all established asthma phenotypes, which was accompanied by apoptosis of airway epithelial cells. In in vitro studies, incubation of NCI-H292 cells with TGFα for 24h increased Bcl-2, MUC5AC and mucous glycoconjugates production, effects that were inhibited by pretreatment of AG1478. AG1478 also induced apoptosis in mucous producing cells, but a MEK inhibitor PD98059 had no effect on apoptosis. Z-VAD-fmk, a caspase inhibitor reduced AG1478-induced apoptosis. From these results, we concluded that the expression and activation of EGFR may play a crucial role in the development of asthma phenotypes and that a tyrosine kinase inhibitor of EGFR may be a useful therapeutic candidate for the restoration of airway remodeling in patients with asthma.
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