Zhao H W, Yin X J, Frazer D, Barger M W, Siegel P D, Millecchia L, Zhong B Z, Tomblyn S, Stone S, Ma J K H, Castranova V, Ma J Y C
Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA.
Mutat Res. 2004 Feb 14;557(2):137-49. doi: 10.1016/j.mrgentox.2003.10.006.
Asphalt fumes are complex mixtures of aerosols and vapors containing various organic compounds, including polycyclic aromatic hydrocarbons (PAHs). Previously, we have demonstrated that inhalation exposure of rats to asphalt fumes resulted in dose-dependent induction of CYP1A1 with concomitant down-regulation of CYP2B1 and increased phase II enzyme quinone reductase activity in the rat lung. In the present study, the potential genotoxic effects of asphalt fume exposure due to altered lung microsomal enzymes were studied. Rats were exposed to air or asphalt fume generated under road paving conditions at various concentrations and sacrificed the next day. Alveolar macrophages (AM) were obtained by bronchoalveolar lavage and examined for DNA damage using the comet assay. To evaluate the systemic genotoxic effect of asphalt fume, micronuclei formation in bone marrow polychromatic erythrocytes (PCEs) was monitored. Lung S9 from various exposure groups was isolated from tissue homogenates and characterized for metabolic activity in activating 2-aminoanthracene (2-AA) and benzo[a]pyrene (BaP) mutagenicity using the Ames test with Salmonella typhimurium YG1024 and YG1029. This study showed that the paving asphalt fumes significantly induced DNA damage in AM, as revealed by DNA migration in the comet assay, in a dose-dependent manner, whereas the micronuclei formation in bone marrow PCEs was not detected even at a very high exposure level (1733 mg h/m3). The conversion of 2-AA to mutagens in the Ames test required lung S9-mediated metabolic activation in a dose-dependent manner. In comparison to the controls, lung S9 from rats exposed to asphalt fume at a total exposure level of 479+/-33 mg h/m3 did not significantly enhance 2-AA mutagenicity with either S. typhimurium YG1024 or YG1029. At a higher total asphalt fume exposure level (1150+/-63 mg h/m3), S9 significantly increased the mutagenicity of 2-AA as compared to the control. However, S9 from asphalt fume-exposed rats did not significantly activate the mutagenicity of BaP in the Ames test. These results show that asphalt fume exposure, which significantly altered both phases I and II metabolic enzymes in lung microsomes, is genotoxic to AM and enhances the metabolic activation of certain mutagens through altered S9 content.
沥青烟是气溶胶和蒸汽的复杂混合物，含有各种有机化合物，包括多环芳烃（PAHs）。此前，我们已经证明，将大鼠吸入沥青烟会导致CYP1A1的剂量依赖性诱导，同时大鼠肺中CYP2B1下调，II相酶醌还原酶活性增加。在本研究中，研究了由于肺微粒体酶改变而导致的沥青烟暴露的潜在遗传毒性作用。将大鼠暴露于铺路条件下产生的不同浓度的空气或沥青烟中，并于次日处死。通过支气管肺泡灌洗获得肺泡巨噬细胞（AM），并使用彗星试验检测DNA损伤。为了评估沥青烟的全身遗传毒性作用，监测骨髓多色红细胞（PCE）中的微核形成。从各种暴露组的组织匀浆中分离出肺S9，并使用鼠伤寒沙门氏菌YG1024和YG1029的Ames试验来表征其在激活2-氨基蒽（2-AA）和苯并[a]芘（BaP）致突变性方面的代谢活性。本研究表明，铺路沥青烟以剂量依赖性方式显著诱导AM中的DNA损伤，如彗星试验中的DNA迁移所示，而即使在非常高的暴露水平（1733 mg h/m3）下也未检测到骨髓PCE中的微核形成。在Ames试验中，2-AA向致突变物的转化需要肺S9介导的代谢激活，且呈剂量依赖性。与对照组相比，总暴露水平为479±33 mg h/m3的暴露于沥青烟的大鼠的肺S9，无论是对鼠伤寒沙门氏菌YG1024还是YG1029，均未显著增强2-AA的致突变性。在更高的总沥青烟暴露水平（1150±63 mg h/m3）下，与对照组相比，S9显著增加了2-AA的致突变性。然而，在Ames试验中，暴露于沥青烟的大鼠的S9并未显著激活BaP的致突变性。这些结果表明，沥青烟暴露显著改变了肺微粒体中的I相和II相代谢酶，对AM具有遗传毒性，并通过改变S9含量增强了某些致突变物的代谢激活。
