Abstract

Nanomaterials (NMs) with tubular structures, such as halloysite nanotubes (HNTs), have potential applications in biomedicine. Although the biocompatibility of HNTs has been investigated before, the toxicity of HNTs to blood vessels is rarely systemically evaluated. Herein, we compared the toxicity of HNTs and multi-walled carbon nanotubes (MWCNTs) to human umbilical vein endothelial cells (HUVECs) in vitro and blood vessels of mice in vivo. HUVECs internalized HNTs and MWCNTs, but the uptake of HNTs was not obviously changed by clathrin inhibitor. Exposure to NMs decreased cellular viability, activated apoptotic proteins and up-regulated adhesion molecules, including soluble vascular cell adhesion molecule 1 (sVCAM-1) and VCAM-1. As the mechanisms, NMs decreased NO levels, eNOS mRNA and eNOS/p-eNOS proteins. Meanwhile, NMs promoted intracellular ROS and autophagy dysfunction, shown as decreased protein levels of LC3, beclin-1 and ATG5. The eNOS regulator Kruppel-like factor 4 (KLF4) was inhibited, but another eNOS regulator KLF4 was surprisingly up-regulated. Under in vivo conditions, ICR mice intravenously injected with NMs (50 μg/mouse, once a day for 5 days) showed an increased percentage of neutrophils, monocytes and basophils. Meanwhile, autophagy dysfunction, eNOS uncoupling, activation of apoptotic proteins and alteration of KLF proteins were also observed in mouse aortas. All of the toxic effects were more pronounced for MWCNTs in comparison with HNTs based on the same mass concentrations. Our results may provide novel insights about the toxicity of NMs with tubular structures to blood vessels. Considering the toxicological data reported here, HNTs are probably safer nanocarriers compared with MWCNTs.

摘要

具有管状结构的纳米材料（NM），例如埃洛石纳米管（HNT），在生物医学中具有潜在的应用。尽管以前已经研究了HNT的生物相容性，但很少系统评估HNT对血管的毒性。在本文中，我们比较了HNT和多壁碳纳米管（MWCNT）对体外人脐静脉内皮细胞（HUVEC）和体内小鼠血管的毒性。HUVEC内化了HNT和MWCNT，但是网格蛋白抑制剂对HNT的吸收没有明显改变。暴露于NMs会降低细胞活力，激活的凋亡蛋白和粘附分子上调，包括可溶性血管细胞粘附分子1（sVCAM-1）和VCAM-1。作为机制，NMs降低了NO含量，eNOS mRNA和eNOS / p-eNOS蛋白。同时，NMs促进细胞内ROS和自噬功能障碍，表现为LC3，beclin-1和ATG5的蛋白质​​水平降低。eNOS调节剂Kruppel样因子4（KLF4）被抑制，但是另一个eNOS调节剂KLF4却被意外地上调。在体内在条件下，静脉内注射NMs（50μg/小鼠，每天一次，连续5天）的ICR小鼠显示出中性粒细胞，单核细胞和嗜碱性粒细胞的百分比增加。同时，在小鼠主动脉中也观察到自噬功能障碍，eNOS解偶联，凋亡蛋白活化和KLF蛋白改变。与基于相同质量浓度的HNT相比，MWCNT的所有毒性作用都更加明显。我们的结果可能提供有关具有管状结构的NMs对血管毒性的新颖见解。考虑到此处报道的毒理学数据，与MWCNT相比，HNTs可能是更安全的纳米载体。