| Research Abstract |
Neutrophil elastase (NE) is known to be one of the most potent proteases capable of deforming and detaching human bronchial epithelial cells (BECs) and inducing interleukin-8 (IL-8) gene expression. However, mechanisms of NE-induced IL-8 gene expression are unclear, especially with respect to how they relate to cellular detachment. In order to elucidate these mechanisms, effects of cell detachment and deformation following mechanical injury or pharmacological stimuli on IL-8 gene expression were examined by Northern analyzes. When BET-1A cells from a human bronchial epithelial cell line were incubated with NE (100nM), trypsin (0.5mg/ml), EGTA (7mM) or EDTA (0.7mM) to induce deformation and detachment, IL-8 mRNA transcript levels were upregulated as demonstrated in a case of mechanical detachment from the culture plate using a cell scraper. These IL-8 gene expression was inhibited by pretreatment with 5mM taxol, a microtubule stabilizing agent. Colchicine or vinblastine, microtubule disrupting agents, induced IL-8 gene expression, which was also inhibited by taxol treatment. These data suggest that structural changes, including deformation of the cytoskeleton, especially microtubules, may contribute to IL-8 gene expression in human BECs. Since detachment and cellular deformation of BECs caused by proteases have been frequently observed in a variety of inflammatory airway diseases, our findings provide evidence that detached or deformed BECs potentially enhance production of inflammatory mediators in the pathogenesis of airway inflammation.
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