title: Intravenous administration of silver nanoparticles causes organ toxicity through intracellular ROS-related loss of inter-endothelial junction.
abstract: BACKGROUND
  Administration of silver nanoparticles (AgNPs) to mice could result in their distribution and accumulation in multiple organs, with notable prominence in liver, lungs, and kidneys. However, how AgNPs transport through blood vesicular system to reach the target organs is unclear, and the precise differences in the mechanisms of toxicity between AgNPs and silver ions still remain elusive. In the present research, the pathological changes on these target organs with a focus on inter-endothelial junction was investigated to gain a new insight of AgNPs toxicity by comparing the mechanisms of action of AgNPs and AgNO3.
  
  
  METHODS
  We investigated the in vitro cytotoxicity of either citrated-coated AgNPs (10, 75, and 110 nm) or silver nitrate (AgNO3) following 24 h incubations (1-40 μg/mL) in the presence of primary human umbilical vein endothelial cells (HUVEC). Meanwhile, we detected the effects of AgNPs on intercellular conjunction and intracellular ROS by VE-cadherin staining and 2', 7'-dichlorodihydrofluorescein diacetate (DCFH-DA) assay, respectively. To assess in vivo toxicity, we administered single or multiple intravenous injections (25 μg Ag for AgNPs and 2.5 μg Ag for AgNO3 per dose) to mice.
  
  
  RESULTS
  In the in vitro study, the TEM observation showed that AgNPs were taken up by endothelial cells while AgNO3 was taken up little. Meanwhile AgNPs incubation induced the elevation of intracellular ROS and down-regulation of VE-cadherin between the endothelial cells and affected the cytoskeleton actin reorganization, which could be rescued by antioxidant N-acetylcysteine. In contrast, AgNO3 caused direct cell death when the concentration was higher than 20 μg/mL and without ROS induction at lower concentration. The release of AgNPs from leaking vessels induced peripheral inflammation in the liver, lungs, and kidneys, and the severity increased in proportion to the diameter of the AgNPs used.
  
  
  CONCLUSIONS
  It is AgNPs but not AgNO3 that were taken up by vascular endothelial cells and induced intracellular ROS elevated, which was closely related to disruption of the integrity of endothelial layer. The AgNPs-induced leakiness of endothelial cells could mediate the common peripheral inflammation in liver, kidney and lung through intravenous exposure.
authors.affiliation: Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Guo
authors.affiliation: Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR, 72079, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Boudreau
authors.affiliation: Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Meng
authors.affiliation: Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, MD, 20740, USA.
authors.forename: Jun-jie
authors.initials: JJ
authors.lastname: Yin
authors.affiliation: Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China. liujian@ibms.pumc.edu.cn.
authors.forename: Jian
authors.initials: J
authors.lastname: Liu
authors.affiliation: Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China. xuhy@pumc.edu.cn.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Xu
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D000975:Antioxidants / Q000494:pharmacology; D015820:Cadherins / Q000378:metabolism; D002478:Cells, Cultured; D056486:Chemical and Drug Induced Liver Injury / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D005260:Female; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007275:Injections, Intravenous; D007365:Intercellular Junctions / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D007668:Kidney / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism; D008168:Lung / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism; D053768:Metal Nanoparticles; D008807:Mice, Inbred BALB C; D009393:Nephritis / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects*; D010539:Permeability; D011014:Pneumonia / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018570:Risk Assessment; D012834:Silver / Q000008:administration & dosage / Q000633:toxicity*; D012835:Silver Nitrate / Q000633:toxicity; D013997:Time Factors; D000099152:Cadherin 5
chemical_list: D015703:Antigens, CD; D000975:Antioxidants; D015820:Cadherins; D017382:Reactive Oxygen Species; D012834:Silver; D012835:Silver Nitrate; D000099152:Cadherin 5
keywords: Inter-endothelial junctions; Peripheral inflammation; ROS; Silver nanoparticles; Silver nitrate