The School of Public Health, University of South China, Hengyang, China.
The First Affiliated Hospital, University of South China, Hengyang, China.
Environ Toxicol. 2019 Nov;34(11):1199-1207. doi: 10.1002/tox.22821. Epub 2019 Jul 11.
Despite intensive research activities, there are still many major knowledge gaps over the potential adverse effects of titanium dioxide nanoparticles (TiO -NPs), one of the most widely produced and used nanoparticles, on human cardiovascular health and the underlying mechanisms. In the present study, alkaline comet assay and cytokinesis-block micronucleus test were employed to determine the genotoxic potentials of four sizes (100, 50, 30, and 10 nm) of anatase TiO -NPs to human umbilical vein endothelial cells (HUVECs) in culture. Also, the intracellular redox statuses were explored through the measurement of the levels of reactive oxygen species (ROS) and reduced glutathione (GSH) with kits, respectively. Meanwhile, the protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2) were also detected by western blot. The results showed that at the exposed levels (1, 5, and 25 μg/mL), all the four sizes of TiO -NPs could elicit an increase of both DNA damage and MN frequency in HUVECs in culture, with a positive dose-dependent and negative size-dependent effect relationship (T100 < T50 < T30 < T10). Also, increased levels of intracellular ROS, but decreased levels of GSH, were found in all the TiO -NP-treated groups. Intriguingly, a very similar manner of dose-dependent and size-dependent effect relationship was observed between the ROS test and both comet assay and MN test, but contrary to that of GSH assay. Correspondingly, the levels of Nrf2 protein were also elevated in the TiO -NP-exposed HUVECs, with an inversely size-dependent effect relationship. These findings indicated that induction of oxidative stress and subsequent genotoxicity might be an important biological mechanism by which TiO -NP exposure would cause detrimental effects to human cardiovascular health.
尽管研究活动十分密集，但对于二氧化钛纳米粒子（TiO 2 -NPs）——这一应用最广泛的纳米粒子之一——对人类心血管健康的潜在不良影响及其潜在机制，我们仍知之甚少。在本研究中，采用碱性彗星试验和胞质分裂阻断微核试验，检测了四种不同粒径（100、50、30 和 10nm）锐钛矿 TiO 2 -NPs 对人脐静脉内皮细胞（HUVECs）的遗传毒性。同时，通过试剂盒分别检测活性氧（ROS）和还原型谷胱甘肽（GSH）的水平来探讨细胞内氧化还原状态。此外，通过 Western blot 检测核因子红细胞 2 相关因子 2（Nrf2）的蛋白水平。结果表明，在暴露水平（1、5 和 25μg/mL）下，四种粒径的 TiO 2 -NPs 均可引起 HUVECs 中 DNA 损伤和微核频率增加，呈正剂量-负粒径的剂量-反应关系（T100 ＜ T50 ＜ T30 ＜ T10）。同时，在所有 TiO 2 -NP 处理组中，细胞内 ROS 水平升高，GSH 水平降低。有趣的是，ROS 试验与彗星试验和微核试验之间观察到了非常相似的剂量-反应关系和粒径-反应关系，但与 GSH 试验相反。相应地，在 TiO 2 -NP 暴露的 HUVECs 中，Nrf2 蛋白水平也升高，呈反粒径依赖性效应关系。这些发现表明，氧化应激的诱导及其随后的遗传毒性可能是 TiO 2 -NP 暴露对人类心血管健康造成有害影响的重要生物学机制。
