Leikauf G D, Driscoll K E, Wey H E
Institute of Environmental Medicine, New York University Medical Center, Tuxedo.
Am Rev Respir Dis. 1988 Feb;137(2):435-42. doi: 10.1164/ajrccm/137.2.435.
Epithelial injury and inflammation have been implicated in ozone-induced airway hyperresponsiveness. Because ozone is relatively insoluble and highly reactive, toxicologic effects of this compound may be limited to the plasma membranes of airway epithelium. We hypothesize that oxidant damage to epithelium may result in elaboration of various eicosanoids, which are known to alter airway smooth muscle responsiveness and epithelial cell functions (including ion transport). To examine eicosanoid metabolism after exposure to 0.1 to 10.0 ppm ozone, epithelial cells derived from bovine trachea were isolated and grown to confluency. Bovine tracheal cells in culture expressed differentiated features characteristic of epithelial cells, including a plasma membrane with a specialized polar morphology, an extensive network of filaments that were connected through intercellular junctional complexes, and keratin-containing monofilaments as determined by indirect immunofluorescent localization. Monolayers were alternately exposed to ozone and culture medium for 2 h in a specially designed in vitro chamber using a rotating inclined platform. Eicosanoid products were measured by the release of [3H]-labeled products from cells incubated with [3H]-arachidonic acid for 24 h before exposure and by the release of immunoreactive products into the cell supernatant. Both methods revealed ozone-induced increases in cyclooxygenase and lipoxygenase product formation with significant increases in prostaglandins E2, F2 alpha, 6-keto F1 alpha, and leukotriene B4. Release rates of immunoreactive products were dose-dependent, and ozone concentrations as low as 0.1 ppm produced an increase in prostaglandin F2 alpha. These findings are consistent with the hypothesis that ozone can augment eicosanoid metabolism in airway epithelial cells.
上皮损伤和炎症与臭氧诱导的气道高反应性有关。由于臭氧相对不溶且反应性高，该化合物的毒理学效应可能仅限于气道上皮的质膜。我们假设上皮的氧化损伤可能导致各种类花生酸的产生，已知这些类花生酸会改变气道平滑肌反应性和上皮细胞功能（包括离子转运）。为了研究暴露于0.1至10.0 ppm臭氧后的类花生酸代谢，分离了源自牛气管的上皮细胞并培养至汇合。培养的牛气管细胞表现出上皮细胞特有的分化特征，包括具有特殊极性形态的质膜、通过细胞间连接复合物连接的广泛细丝网络以及通过间接免疫荧光定位确定的含角蛋白的单丝。使用旋转倾斜平台在专门设计的体外培养箱中，将单层细胞交替暴露于臭氧和培养基中2小时。通过在暴露前用[3H]-花生四烯酸孵育细胞24小时后释放[3H]标记产物以及将免疫反应性产物释放到细胞上清液中来测量类花生酸产物。两种方法均显示臭氧诱导环氧化酶和脂氧化酶产物形成增加，前列腺素E2、F2α、6-酮F1α和白三烯B4显著增加。免疫反应性产物的释放速率呈剂量依赖性，低至0.1 ppm的臭氧浓度即可使前列腺素F2α增加。这些发现与臭氧可增强气道上皮细胞类花生酸代谢的假设一致。
