title: Comparison of UVA-induced ROS and sunscreen nanoparticle-generated ROS in human immune cells.
abstract: Oxidative damage to cells and tissues from free radicals induced by ultraviolet (UV) irradiation can be attenuated by sunscreen components, such as ZnO and TiO2 nanoparticles (NPs). Although it is known that reactive oxygen species (ROS) are generated by cells upon exposure to ZnO and TiO2 NPs, it is unknown to what extent the amount generated is altered with UV co-exposure. As it is a critical component for determining the relative risk of these NPs when used in sunscreen formulations, we have investigated ROS generation by these NPs in human THP-1 monocyte immune cells following UVA co-exposure. Whilst the applied UVA dose (6.7 J cm(-2)) did not alter cell viability after 24 h, it induced significant ROS production - causing a 7-fold increase in intracellular peroxide and 3.3-fold increase in mitochondrial superoxide levels after 1 h. However, co-exposure to NPs and UVA generated the same or less ROS than with UVA exposure alone, with the exception of anatase TiO2, which showed significantly increased levels. These findings indicate that ROS generation from nanosunscreens is, in most cases, an insignificant contributor to the overall risk associated with oxidative stress from UVA exposure itself.
authors.affiliation: School of Medical Sciences, and NanoSafe Australia, RMIT University, Bundoora, VIC 3083, Australia. paul.wright@rmit.edu.au.
authors.forename: Cenchao
authors.initials: C
authors.lastname: Shen
authors.forename: Terence W
authors.initials: TW
authors.lastname: Turney
authors.forename: Terrence J
authors.initials: TJ
authors.lastname: Piva
authors.forename: Bryce N
authors.initials: BN
authors.lastname: Feltis
authors.forename: Paul F A
authors.initials: PF
authors.lastname: Wright
mesh_terms: D002470:Cell Survival; D006801:Humans; D009000:Monocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000528:radiation effects; D053758:Nanoparticles / Q000737:chemistry*; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism* / Q000528:radiation effects; D013473:Sunscreening Agents / Q000737:chemistry* / Q000494:pharmacology*; D014025:Titanium / Q000737:chemistry / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014466:Ultraviolet Rays; D015034:Zinc Oxide / Q000737:chemistry / Q000494:pharmacology
chemical_list: D017382:Reactive Oxygen Species; D013473:Sunscreening Agents; C009495:titanium dioxide; D014025:Titanium; D015034:Zinc Oxide