Department of Public Health, Aarhus University, Bartholins Allé 2, DK-8000 Aarhus C, Denmark.
Chem Biol Interact. 2013 Jun 25;204(1):28-38. doi: 10.1016/j.cbi.2013.04.007. Epub 2013 Apr 25.
Much of the concerns regarding engineered nanoparticle (NP) toxicity are based on knowledge from previous studies on particles in ambient air or occupational situations. E.g., the effects of exposure to silica dust particles have been studied intensely due to the carcinogenicity of crystalline silica. However, the increasing usage of engineered amorphous silica NPs has emphasized the need for further mechanistic insight to predict the consequences of exposure to the amorphous type of silica NPs. The present study focused on the in vitro biological effects following exposure to well-dispersed, BSA-stabilized, amorphous silica NPs whereas unmodified silica NPs where included for reasons of comparison. The cytotoxicity of the silica NPs was investigated in six different cell lines (A549, THP-1, CaCo-2, ASB-XIV, J-774A.1, and Colon-26) selected to explore the significance of organ and species sensitivity in vitro. Viability data demonstrated that macrophages were most sensitive to silica NP and interestingly, murine cell lines were generally found to be more sensitive than comparable human cell lines. Further studies were conducted in the human epithelial lung cell line, A549, to explore the molecular mechanism of silica toxicity. Generation of reactive oxygen species, one of the proposed toxicological mechanisms of NPs, was investigated in A549 cells by the dichlorofluorescin (DCF) assay to be significantly induced at NP concentrations above 113 μg/mL. However, induction of oxidative stress related pathways was not found after silica NP exposure for 24 h in gene array studies conducted in A549 cells at a relatively low NP concentration (EC20). Up-regulated genes (more than 2-fold) were primarily related to lipid metabolism and biosynthesis whereas down-regulated genes included several processes such as transcription, cell junction, extra cellular matrix (ECM)-receptor interaction and others. Thus, gene expression data proposes that several cellular processes other than oxidative stress could be affected by exposure to silica NPs.
人们对工程纳米粒子（NP）毒性的担忧主要基于对环境空气中或职业环境中颗粒的先前研究知识。例如，由于结晶二氧化硅的致癌性，人们已经对暴露于二氧化硅粉尘颗粒的影响进行了深入研究。然而，由于工程非晶态二氧化硅 NPs 的使用不断增加，因此需要进一步的机制研究来预测暴露于非晶态二氧化硅 NPs 的后果。本研究重点研究了暴露于分散良好的 BSA 稳定的非晶态二氧化硅 NPs 后体外的生物学效应，同时还包括了未修饰的二氧化硅 NPs 以作比较。选用六种不同的细胞系（A549、THP-1、CaCo-2、ASB-XIV、J-774A.1 和 Colon-26）来研究器官和物种敏感性的体外意义，以研究二氧化硅 NPs 的细胞毒性。存活率数据表明，巨噬细胞对二氧化硅 NPs 最敏感，有趣的是，与相应的人细胞系相比，鼠细胞系通常被发现更敏感。在人上皮肺细胞系 A549 中进行了进一步的研究，以探讨二氧化硅毒性的分子机制。通过二氯荧光素（DCF）测定法研究了 A549 细胞中活性氧的产生，结果表明，当 NP 浓度高于 113μg/mL 时，活性氧的产生会显著增加。然而，在基因芯片研究中，当 A549 细胞以相对较低的 NP 浓度（EC20）暴露于二氧化硅 NP 24 小时后，并未发现与氧化应激相关的途径被诱导。上调基因（超过 2 倍）主要与脂质代谢和生物合成有关，而下调基因包括转录、细胞连接、细胞外基质（ECM）-受体相互作用等多个过程。因此，基因表达数据表明，除了氧化应激之外，暴露于二氧化硅 NPs 还可能影响其他几个细胞过程。
