Fanizza Carla, Fresegna Anna Maria, Maiello Raffaele, Paba Emilia, Cavallo Delia
DIPIA, ISPESL, National Institute for Occupational Safety and Prevention, Via Urbana 167, 00184 Rome, Italy.
J Appl Toxicol. 2009 Aug;29(6):537-44. doi: 10.1002/jat.1440.
A causal pathway between quartz, silicosis and lung cancer has been postulated. The aim of our study was to assess cytotoxic effects induced in a human lung epithelial cell line (A549) by exposure to alpha-quartz. Cells were exposed to respirable alpha-quartz (SRM1878a, NIST) at 25, 50 or 100 microg ml(-1 )for 24 h and at 50 or 100 microg ml(-1) for 48 h. Cytotoxic effects were analyzed by scanning electron microscopy (SEM), apoptotic morphology analysis with Hoechst staining and lactate dehydrogenase (LDH) release assay. In cells exposed to alpha-quartz for 24 h, a concentration-dependent bleb development and in particular the localization of blebs at the cell edge at higher concentrations were observed. The blebbing phenomenon was more evident after 48 h of exposure to 50 or to 100 microg ml(-1) of alpha-quartz and large blebs were localized at the cell edge. At the same concentrations surface smoothing was also observed. Moreover the presence of holes and tears was detected at the highest concentration both at 24 and 48 h. Results of morphological analysis with Hoechst stain evidenced an increase concentration-time dependent of apoptotic cell percentage that was more marked after 48 h exposure to 100 microg ml(-1) and a prevalence of late apoptosis stage with the increase of exposure time and concentration. Cells exposed to 50 or 100 microg ml(-1) of alpha-quartz for 24 and 48 h produced a significant increase in LDH release. The concentration-time-dependent bleb induction evidenced by SEM correlates with the increase of apoptotic cells and LDH activity release, demonstrating the onset of cytotoxic effects in human lung cells exposed to alpha-quartz.
石英、矽肺和肺癌之间的因果关系已被提出。我们研究的目的是评估人肺上皮细胞系（A549）暴露于α-石英后诱导的细胞毒性作用。将细胞暴露于可吸入的α-石英（SRM1878a，美国国家标准与技术研究院），浓度分别为25、50或100μg/ml，暴露24小时，以及浓度为50或100μg/ml，暴露48小时。通过扫描电子显微镜（SEM）、用Hoechst染色进行凋亡形态分析和乳酸脱氢酶（LDH）释放试验分析细胞毒性作用。在暴露于α-石英24小时的细胞中，观察到浓度依赖性的气泡形成，特别是在较高浓度下气泡在细胞边缘的定位。暴露于50或100μg/ml的α-石英48小时后，气泡形成现象更明显，大的气泡位于细胞边缘。在相同浓度下，还观察到表面平滑。此外，在24小时和48小时的最高浓度下均检测到孔洞和撕裂。Hoechst染色的形态学分析结果表明，凋亡细胞百分比呈浓度-时间依赖性增加，在暴露于100μg/ml 48小时后更为明显，并且随着暴露时间和浓度的增加，晚期凋亡阶段占优势。暴露于50或100μg/ml的α-石英24小时和48小时的细胞导致LDH释放显著增加。SEM显示的浓度-时间依赖性气泡诱导与凋亡细胞增加和LDH活性释放相关，证明暴露于α-石英的人肺细胞中出现了细胞毒性作用。
