Singh Seema, Shi Tingming, Duffin Rodger, Albrecht Catrin, van Berlo Damien, Höhr Doris, Fubini Bice, Martra Gianmario, Fenoglio Ivana, Borm Paul J A, Schins Roel P F
Institut für umweltmedizinische Forschung (IUF) an der Heinrich-Heine Universität Düsseldorf gGmbH, Germany.
Toxicol Appl Pharmacol. 2007 Jul 15;222(2):141-51. doi: 10.1016/j.taap.2007.05.001. Epub 2007 May 18.
Inhaled ultrafine particles show considerably stronger pulmonary inflammatory effects when tested at equal mass dose with their fine counterparts. However, the responsible mechanisms are not yet fully understood. We investigated the role of particle size and surface chemistry in initiating pro-inflammatory effects in vitro in A549 human lung epithelial cells on treatment with different model TiO(2) particles. Two samples of TiO(2), i.e. fine (40-300 nm) and ultrafine (20-80 nm) were tested in their native forms as well as upon surface methylation, as was confirmed by Fourier transformed infrared spectroscopy. Radical generation during cell treatment was determined by electron paramagnetic resonance with 5,5-dimethyl-1-pyrroline-N-oxide or 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl. Interleukin-8 mRNA expression/release was determined by RT-PCR and ELISA, whereas particle uptake was evaluated by transmission electron microscopy. TiO(2) particles were rapidly taken up by the cells, generally as membrane bound aggregates and large intracellular aggregates in vesicles, vacuoles and lamellar bodies. Aggregate size tended to be smaller for the ultrafine samples and was also smaller for methylated fine TiO(2) when compared to non-methylated fine TiO(2). No particles were observed inside nuclei or any other vital organelle. Both ultrafine TiO(2) samples but not their fine counterparts elicited significantly stronger oxidant generation and IL-8 release, despite their aggregation state and irrespective of their methylation. The present data indicate that ultrafine TiO(2), even as aggregates/agglomerates, can trigger inflammatory responses that appear to be driven by their large surface area. Furthermore, our results indicate that these effects result from oxidants generated during particle-cell interactions through a yet to be elucidated mechanism(s).
当吸入的超细颗粒与细颗粒以相等质量剂量进行测试时，显示出更强的肺部炎症效应。然而，其作用机制尚未完全明确。我们研究了颗粒大小和表面化学性质在体外对A549人肺上皮细胞产生促炎作用的过程中所起的作用，采用不同的模型TiO₂颗粒进行处理。通过傅里叶变换红外光谱证实，对两种TiO₂样品，即细颗粒（40 - 300nm）和超细颗粒（20 - 80nm），以其天然形式以及表面甲基化形式进行测试。细胞处理过程中的自由基生成通过电子顺磁共振结合5,5 - 二甲基 - 1 - 吡咯啉 - N - 氧化物或4 - 羟基 - 2,2,6,6 - 四甲基哌啶 - 1 - 氧基来测定。白细胞介素 - 8 mRNA表达/释放通过逆转录聚合酶链反应和酶联免疫吸附测定来确定，而颗粒摄取则通过透射电子显微镜进行评估。TiO₂颗粒能迅速被细胞摄取，通常以膜结合聚集体以及在囊泡、液泡和板层小体中的大型细胞内聚集体形式存在。超细颗粒样品的聚集体尺寸往往较小，与未甲基化的细TiO₂相比，甲基化的细TiO₂的聚集体尺寸也较小。在细胞核或任何其他重要细胞器内均未观察到颗粒。尽管其聚集状态以及甲基化情况不同，但两种超细TiO₂样品均能引发比细颗粒更强的氧化剂生成和白细胞介素 - 8释放。目前的数据表明，即使是聚集态/团聚态的超细TiO₂也能引发炎症反应，这似乎是由其大表面积所驱动的。此外，我们的结果表明，这些效应是由颗粒 - 细胞相互作用过程中通过尚未阐明的机制产生的氧化剂所导致的。
