title: Mechanism of neutrophil activation and toxicity elicited by engineered nanomaterials.
abstract: The effects of nanomaterials (NMs) on biological systems, especially their ability to stimulate inflammatory responses requires urgent investigation. We evaluated the response of the human differentiated HL60 neutrophil-like cell line to NMs. It was hypothesised that NM physico-chemical characteristics would influence cell responsiveness by altering intracellular Ca2+ concentration [Ca2+]i and reactive oxygen species production. Cells were exposed (1.95-125 μg/ml, 24 h) to silver (Ag), zinc oxide (ZnO), titanium dioxide (TiO2), multi-walled carbon nanotubes (MWCNTs) or ultrafine carbon black (ufCB) and cytotoxicity assessed (alamar blue assay). Relatively low (TiO2, MWCNTs, ufCB) or high (Ag, ZnO) cytotoxicity NMs were identified. Sub-lethal impacts of NMs on cell function were investigated for selected NMs only, namely TiO2, Ag and ufCB. Only Ag stimulated cell activation. Within minutes, Ag stimulated an increase in [Ca2+]i (in Fura-2 loaded cells), and a prominent inward ion current (assessed by electrophysiology). Within 2-4 h, Ag increased superoxide anion release and stimulated cytokine production (MCP-1, IL-8) that was diminished by Ca2+ inhibitors or trolox. Light microscopy demonstrated that cells had an activated phenotype. In conclusion NM toxicity was ranked; Ag>ufCB>TiO2, and the battery of tests used provided insight into the mechanism of action of NM toxicity to guide future testing strategies.
authors.affiliation: School of Life Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom. Electronic address: h.johnston@hw.ac.uk.
authors.forename: Helinor
authors.initials: H
authors.lastname: Johnston
authors.affiliation: School of Life Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
authors.forename: David M
authors.initials: DM
authors.lastname: Brown
authors.affiliation: School of Life Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
authors.forename: Nilesh
authors.initials: N
authors.lastname: Kanase
authors.affiliation: Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
authors.forename: Matthew
authors.initials: M
authors.lastname: Euston
authors.affiliation: School of Life Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
authors.forename: Birgit K
authors.initials: BK
authors.lastname: Gaiser
authors.affiliation: School of Life Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom; MRC Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom.
authors.forename: Calum T
authors.initials: CT
authors.lastname: Robb
authors.affiliation: School of Life Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Dyrynda
authors.affiliation: MRC Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom.
authors.forename: Adriano G
authors.initials: AG
authors.lastname: Rossi
authors.affiliation: Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
authors.forename: Euan R
authors.initials: ER
authors.lastname: Brown
authors.affiliation: School of Life Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
authors.forename: Vicki
authors.initials: V
authors.lastname: Stone
mesh_terms: D002118:Calcium / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D016207:Cytokines / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D049329:Nanostructures / Q000633:toxicity*; D037742:Nanotubes, Carbon / Q000633:toxicity; D018375:Neutrophil Activation / Q000187:drug effects*; D012834:Silver / Q000633:toxicity; D053260:Soot / Q000633:toxicity; D013481:Superoxides / Q000378:metabolism; D014025:Titanium / Q000633:toxicity; D015034:Zinc Oxide / Q000633:toxicity
chemical_list: D016207:Cytokines; D037742:Nanotubes, Carbon; D053260:Soot; D013481:Superoxides; C009495:titanium dioxide; D012834:Silver; D014025:Titanium; D015034:Zinc Oxide; D002118:Calcium
keywords: Ca(2+); Mechanism; Nanomaterial; Neutrophil; Toxicity