Burvall Karin, Palmberg Lena, Larsson Kjell
The National Institute of Environmental Medicine, Lung and Allergy Research, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
Life Sci. 2004 Oct 22;75(23):2733-49. doi: 10.1016/j.lfs.2004.03.037.
Exposure in a swine confinement building of previously unexposed subjects leads to an intense inflammatory reaction with increased number of inflammatory cells and mediators in the upper and lower respiratory tract. In vitro the organic dust induces cytokine release from respiratory epithelial cells. Whether the dust-induced release of IL-6 and IL-8 protein from A549 lung epithelial cells is a result of sustained mRNA expression during the 24 h exposure generally applied is unknown. Furthermore, it is not known if the previously demonstrated effects on basal and dust-induced IL-6 and IL-8 protein production by 8-bromo-cyclicAMP are time-dependent, since only cumulative effects are observed by measurement of cytokine release. In the present study reverse transcription- (RT-) PCR was applied to investigate expression of IL-6 and IL-8 mRNA in A549 cells exposed to organic dust in a time-kinetic manner. The dust increased IL-6 and IL-8 mRNA expression at all times tested (1 h-48 h). The IL-6 mRNA expression peaked at 1-1.5 h and was reduced with time, whereas the dust-induced IL-8 mRNA expression remained elevated. At 1-1.5 h, 8-bromo-cAMP stimulated basal and dust-induced IL-6 mRNA expression and attenuated dust-induced IL-8 mRNA expression by activation of protein kinase A- (PKA), as assessed with the PKA inhibitor H-89. On prolonged exposure (>3 h), the dust-induced IL-6 mRNA was PKA-dependently decreased, whereas at 17 h and longer the IL-8 mRNA expression induced by a dust-suspension with 8-bromo-cAMP was similar to, or enhanced, relative to the dust-induced IL-8 mRNA. Thus, 8-bromo-cAMP exerted opposite action on dust-induced IL-6 and IL-8 mRNA expression with time.
将先前未接触过的个体置于猪舍中，会引发强烈的炎症反应，导致上、下呼吸道炎症细胞和介质数量增加。在体外，有机粉尘可诱导呼吸道上皮细胞释放细胞因子。一般在24小时暴露期间，有机粉尘诱导A549肺上皮细胞释放白细胞介素-6（IL-6）和白细胞介素-8（IL-8）蛋白是否是持续mRNA表达的结果尚不清楚。此外，此前已证明8-溴环磷酸腺苷（8-bromo-cyclicAMP）对基础和粉尘诱导的IL-6和IL-8蛋白产生有影响，但这种影响是否具有时间依赖性尚不清楚，因为通过测量细胞因子释放仅观察到累积效应。在本研究中，应用逆转录-聚合酶链反应（RT-PCR）以时间动力学方式研究暴露于有机粉尘的A549细胞中IL-6和IL-8 mRNA的表达。在所有测试时间（1小时至48小时），粉尘均增加了IL-6和IL-8 mRNA的表达。IL-6 mRNA表达在1至1.5小时达到峰值，随后随时间降低，而粉尘诱导的IL-8 mRNA表达则持续升高。在1至1.5小时，8-溴环磷酸腺苷通过激活蛋白激酶A（PKA）刺激基础和粉尘诱导的IL-6 mRNA表达，并减弱粉尘诱导的IL-8 mRNA表达，这一作用通过PKA抑制剂H-89进行评估。在长时间暴露（>3小时）时，粉尘诱导的IL-6 mRNA呈PKA依赖性降低，而在17小时及更长时间，8-溴环磷酸腺苷与粉尘悬浮液诱导的IL-8 mRNA表达与粉尘诱导的IL-8 mRNA相似或增强。因此，8-溴环磷酸腺苷随时间对粉尘诱导的IL-6和IL-8 mRNA表达发挥相反作用。
