title: Silver nanowire interactions with primary human alveolar type-II epithelial cell secretions: contrasting bioreactivity with human alveolar type-I and type-II epithelial cells.
abstract: Inhaled nanoparticles have a high deposition rate in the alveolar units of the deep lung. The alveolar epithelium is composed of type-I and type-II epithelial cells (ATI and ATII respectively) and is bathed in pulmonary surfactant. The effect of native human ATII cell secretions on nanoparticle toxicity is not known. We investigated the cellular uptake and toxicity of silver nanowires (AgNWs; 70 nm diameter, 1.5 μm length) with human ATI-like cells (TT1), in the absence or presence of Curosurf® (a natural porcine pulmonary surfactant with a low amount of protein) or harvested primary human ATII cell secretions (HAS; containing both the complete lipid as well as the full protein complement of human pulmonary surfactant i.e. SP-A, SP-B, SP-C and SP-D). We hypothesised that Curosurf® or HAS would confer improved protection for TT1 cells, limiting the toxicity of AgNWs. In agreement with our hypothesis, HAS reduced the inflammatory and reactive oxygen species (ROS)-generating potential of AgNWs with exposed TT1 cells. For example, IL-8 release and ROS generation was reduced by 38% and 29%, respectively, resulting in similar levels to that of the non-treated controls. However in contrast to our hypothesis, Curosurf® had no effect. We found a significant reduction in AgNW uptake by TT1 cells in the presence of HAS but not Curosurf. Furthermore, we show that the SP-A and SP-D are likely to be involved in this process as they were found to be specifically bound to the AgNWs. While ATI cells appear to be protected by HAS, evidence suggested that ATII cells, despite no uptake, were vulnerable to AgNW exposure (indicated by increased IL-8 release and ROS generation and decreased intracellular SP-A levels one day post-exposure). This study provides unique findings that may be important for the study of lung epithelial-endothelial translocation of nanoparticles in general and associated toxicity within the alveolar unit.
authors.affiliation: Lung Cell Biology, Section of Pharmacology and Toxicology, Airways Disease, National Heart & Lung Institute, Imperial College London, London, UK. t.tetley@imperial.ac.uk.
authors.forename: Sinbad
authors.initials: S
authors.lastname: Sweeney
authors.forename: Ioannis G
authors.initials: IG
authors.lastname: Theodorou
authors.forename: Marta
authors.initials: M
authors.lastname: Zambianchi
authors.forename: Shu
authors.initials: S
authors.lastname: Chen
authors.forename: Andrew
authors.initials: A
authors.lastname: Gow
authors.forename: Stephan
authors.initials: S
authors.lastname: Schwander
authors.forename: Junfeng Jim
authors.initials: JJ
authors.lastname: Zhang
authors.forename: Kian Fan
authors.initials: KF
authors.lastname: Chung
authors.forename: Milo S P
authors.initials: MS
authors.lastname: Shaffer
authors.forename: Mary P
authors.initials: MP
authors.lastname: Ryan
authors.forename: Alexandra E
authors.initials: AE
authors.lastname: Porter
authors.forename: Teresa D
authors.initials: TD
authors.lastname: Tetley
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D016207:Cytokines / Q000276:immunology*; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D006801:Humans; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity; D053770:Nanowires / Q000737:chemistry / Q000633:toxicity*; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D011663:Pulmonary Surfactants / Q000737:chemistry*; D012834:Silver / Q000737:chemistry / Q000633:toxicity*
chemical_list: D016207:Cytokines; D011663:Pulmonary Surfactants; D012834:Silver