title: An investigation into the interactions of gold nanoparticles and anti-arthritic drugs with macrophages, and their reactivity towards thioredoxin reductase.
abstract: Gold(I) complexes are an important tool in the arsenal of established approaches for treating rheumatoid arthritis (RA), while some recent studies have suggested that gold nanoparticles (Au NPs) may also be therapeutically efficacious. These observations prompted the current biological studies involving gold(I) anti-RA agents and Au NPs, which are aimed towards improving our knowledge of how they work. The cytotoxicity of auranofin, aurothiomalate, aurothiosulfate and Au NPs towards RAW264.7 macrophages was evaluated using the MTT assay, with the former compound proving to be the most toxic. The extent of cellular uptake of the various gold agents was determined using graphite furnace atomic absorption spectrometry, while their distribution within macrophages was examined using microprobe synchrotron radiation X-ray fluorescence spectroscopy. The latter technique showed accumulation of gold in discrete regions of the cell, and co-localisation with sulfur in the case of cells treated with aurothiomalate or auranofin. Electrospray ionization mass spectrometry was used to characterize thioredoxin reductase (TrxR) in which the penultimate selenocysteine residue was replaced by cysteine. Mass spectra of solutions of TrxR and aurothiomalate, aurothiosulfate or auranofin showed complexes containing bare gold atoms bound to the protein, or protein adducts containing gold atoms retaining some of their initial ligands. These results support TrxR being an important target of gold(I) drugs used to treat RA, while the finding that Au NPs are incorporated into macrophages, but elicit little toxicity, indicates further exploration of their potential for treatment of RA is warranted.
authors.affiliation: Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Lloyd R A
authors.initials: LR
authors.lastname: James
authors.affiliation: Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Zhi-Qiang
authors.initials: ZQ
authors.lastname: Xu
authors.affiliation: Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; School of Biological Sciences, University of Wollongong, Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
authors.forename: Ronald
authors.initials: R
authors.lastname: Sluyter
authors.affiliation: Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Emma L
authors.initials: EL
authors.lastname: Hawksworth
authors.affiliation: Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Celine
authors.initials: C
authors.lastname: Kelso
authors.affiliation: X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
authors.forename: Barry
authors.initials: B
authors.lastname: Lai
authors.affiliation: Australian Synchrotron, Clayton, VIC 3168, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Paterson
authors.affiliation: Australian Synchrotron, Clayton, VIC 3168, Australia.
authors.forename: Martin D
authors.initials: MD
authors.lastname: de Jonge
authors.affiliation: Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Dixon
authors.affiliation: Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Beck
authors.affiliation: Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Ralph
authors.affiliation: Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia; School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia. Electronic address: carolynd@uow.edu.au.
authors.forename: Carolyn T
authors.initials: CT
authors.lastname: Dillon
mesh_terms: D001310:Auranofin / Q000378:metabolism / Q000633:toxicity; D006046:Gold / Q000032:analysis; D006052:Gold Sodium Thiomalate / Q000378:metabolism / Q000633:toxicity; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D053768:Metal Nanoparticles / Q000633:toxicity*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013052:Spectrometry, X-Ray Emission / Q000379:methods; D013054:Spectrophotometry, Atomic / Q000379:methods; D013880:Thioredoxin-Disulfide Reductase / Q000737:chemistry / Q000378:metabolism*
chemical_list: D006052:Gold Sodium Thiomalate; D001310:Auranofin; D006046:Gold; D013880:Thioredoxin-Disulfide Reductase
keywords: Gold complexes; Gold nanoparticles; Macrophages; Rheumatoid arthritis; Thioredoxin reductase