Department of Environmental and Occupational Health Sciences, School of Public Health and Information Sciences, University of Louisville, 485 E. Gray Street, Louisville, KY 40209, USA.
Toxicol Lett. 2010 May 19;195(1):82-9. doi: 10.1016/j.toxlet.2010.02.010. Epub 2010 Feb 18.
Recent studies demonstrated that exposure to nanoparticles could enhance the adhesion of endothelial cells and modify the membrane structure of vascular endothelium. The endothelium plays an important role in the regulation of fibrinolysis, and imbalance of the fibrinolysis system potential contributes to the development of thrombosis. Plasminogen activator inhibitor-1 (PAI-1) is the most potent endogenous inhibitor of fibrinolysis and is involved in the pathogenesis of several cardiovascular diseases. The aim of this study was to investigate the alteration of PAI-1 expression in mouse pulmonary microvascular endothelial cells (MPMVEC) exposed to the metal nanoparticles that are known to be reactive, and the potential underlying mechanisms. We compared the alteration of PAI-1 expression in MPMVEC exposed to non-toxic doses of nano-size copper (II) oxide (Nano-CuO) and nano-size titanium dioxide (Nano-TiO(2)). Our results showed that Nano-CuO caused a dose- and time-dependent increase in PAI-1 expression. Moreover, exposure of MPMVEC to Nano-CuO caused reactive oxygen species (ROS) generation that was abolished by pre-treatment of cells with ROS scavengers or inhibitors, DPI, NAC and catalase. Exposure of MPMVEC to Nano-CuO also caused a dose- and time-dependent increase in p38 phosphorylation by Western blot. These effects were significantly attenuated when MPMVEC were pre-treated with DPI, NAC and catalase. To further investigate the role of p38 phosphorylation in Nano-CuO-induced PAI-1 overexpression, the p38 inhibitor, SB203580, was used to pre-treat cells prior to Nano-CuO exposure. We found that Nano-CuO-induced overexpression of PAI-1 was attenuated by p38 inhibitor pre-treatment. However, Nano-TiO(2) did not show the same results. Our results suggest that Nano-CuO caused up-regulation of PAI-1 in endothelial cells is mediated by p38 phosphorylation due to oxidative stress. These findings have important implications for understanding the potential health effects of metal nanoparticle exposure.
最近的研究表明，纳米颗粒的暴露可以增强内皮细胞的黏附，并改变血管内皮的膜结构。内皮在纤溶调节中起着重要作用，纤溶系统平衡的潜在失衡可能导致血栓形成。纤溶酶原激活物抑制剂-1（PAI-1）是最有效的内源性纤溶抑制物，参与多种心血管疾病的发病机制。本研究旨在探讨已知具有反应性的金属纳米颗粒暴露对小鼠肺微血管内皮细胞（MPMVEC）中 PAI-1 表达的改变及其潜在机制。我们比较了无毒剂量的纳米尺寸氧化铜（Nano-CuO）和纳米尺寸二氧化钛（Nano-TiO2）暴露对 MPMVEC 中 PAI-1 表达的改变。结果表明，Nano-CuO 引起 PAI-1 表达的剂量和时间依赖性增加。此外，Nano-CuO 暴露引起活性氧（ROS）的产生，该产生可被细胞用 ROS 清除剂或抑制剂 DPI、NAC 和过氧化氢酶预处理所消除。Nano-CuO 暴露还引起 MPMVEC 中 p38 磷酸化的剂量和时间依赖性增加。当 MPMVEC 用 DPI、NAC 和过氧化氢酶预处理时，这些作用明显减弱。为了进一步研究 p38 磷酸化在 Nano-CuO 诱导的 PAI-1 过表达中的作用，用 p38 抑制剂 SB203580 预处理细胞，然后用 Nano-CuO 暴露。结果发现，p38 抑制剂预处理可减弱 Nano-CuO 诱导的 PAI-1 过表达。然而，Nano-TiO2 则没有表现出相同的结果。研究结果表明，由于氧化应激，Nano-CuO 引起的内皮细胞中 PAI-1 的上调是通过 p38 磷酸化介导的。这些发现对理解金属纳米颗粒暴露的潜在健康影响具有重要意义。
