Knaapen Ad M, Albrecht Catrin, Becker Andrea, Höhr Doris, Winzer Astrid, Haenen Guido R, Borm Paul J A, Schins Roel P F
Institut für umweltmedizinische Forschung at the University of Düsseldorf, Department of Particle Toxicology, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany.
Carcinogenesis. 2002 Jul;23(7):1111-20. doi: 10.1093/carcin/23.7.1111.
Respirable quartz has been classified as a human lung carcinogen (IARC, 1997). However, the mechanisms involved in quartz-induced carcinogenesis remain unclear. The aim of the present study was to investigate acute DNA damage in epithelial lung cells from rats exposed to quartz. Since surface reactivity is considered to play a crucial role in the toxicity of quartz, the effect of surface modifying agents polyvinylpyridine-N-oxide (PVNO) and aluminium lactate (AL) was evaluated. Therefore, rats were instilled with quartz (DQ12, 2 mg/rat) or quartz treated with PVNO or AL. After 3 days animals were killed and brochoalveolar lavage (BAL) was performed to evaluate inflammatory cell influx. BAL-fluid levels of lactate dehydrogenase (LDH), alkaline phosphatase (AP) and total protein were used as lung damage markers. Neutrophil activation was assessed by myeloperoxidase (MPO) measurement, and total antioxidant capacity of the BAL-fluid was determined using the TEAC (trolox equivalent antioxidant capacity) assay. Lung epithelial cells were isolated and DNA strand breakage was determined by single cell gel electrophoresis (comet assay). DNA damage was significantly increased in epithelial cells from rats instilled with DQ12, whereas no enhanced DNA strand breakage was observed when quartz was treated with PVNO or AL. Total protein, LDH and TEAC were increased in rats treated with native quartz, and this was inhibited by both coatings. A significant correlation between neutrophil numbers and MPO levels was observed, indicating neutrophil activation. Inhibition of DNA damage by both coatings was paralleled by a reduction of neutrophil influx as well as MPO activity. In this study we provide evidence that modification of the particle surface prevents DNA strand breakage in epithelial lung cells from quartz-exposed rats. Furthermore, the present data show the feasibility of our in vivo model to evaluate the role of inflammation, antioxidant status, and cytotoxicity in particle-induced DNA damage.
可吸入性石英已被列为人类肺癌致癌物（国际癌症研究机构，1997年）。然而，石英诱导致癌作用的机制仍不清楚。本研究的目的是调查暴露于石英的大鼠肺上皮细胞中的急性DNA损伤。由于表面反应性被认为在石英的毒性中起关键作用，因此评估了表面改性剂聚乙烯吡啶-N-氧化物（PVNO）和乳酸铝（AL）的作用。因此，给大鼠滴注石英（DQ12，2mg/只大鼠）或用PVNO或AL处理过的石英。3天后处死动物并进行支气管肺泡灌洗（BAL）以评估炎症细胞流入。BAL液中乳酸脱氢酶（LDH）、碱性磷酸酶（AP）和总蛋白水平用作肺损伤标志物。通过髓过氧化物酶（MPO）测量评估中性粒细胞活化，并使用TEAC（trolox等效抗氧化能力）测定法测定BAL液的总抗氧化能力。分离肺上皮细胞并通过单细胞凝胶电泳（彗星试验）测定DNA链断裂。滴注DQ12的大鼠上皮细胞中的DNA损伤显著增加，而用PVNO或AL处理石英时未观察到DNA链断裂增强。天然石英处理的大鼠中总蛋白、LDH和TEAC增加，并且两种涂层均抑制了这种增加。观察到中性粒细胞数量与MPO水平之间存在显著相关性，表明中性粒细胞活化。两种涂层对DNA损伤的抑制与中性粒细胞流入以及MPO活性的降低同时发生。在本研究中，我们提供证据表明颗粒表面的改性可防止暴露于石英的大鼠肺上皮细胞中的DNA链断裂。此外，目前的数据表明我们的体内模型在评估炎症、抗氧化状态和细胞毒性在颗粒诱导的DNA损伤中的作用方面是可行的。
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