title: A commercial mixture of the brominated flame retardant pentabrominated diphenyl ether (DE-71) induces respiratory burst in human neutrophil granulocytes in vitro.
abstract: Polybrominated diphenyl ethers (PBDEs) are widely used brominated flame retardants (BFRs), which have become ubiquitous in the environment. This study investigates the effects of the pentabrominated diphenyl ether mixture, DE-71, on human neutrophil granulocytes in vitro. DE-71 enhanced production of reactive oxygen species (ROS) in a concentration-dependent manner measured as lucigenin-amplified chemiluminescence. Octabrominated diphenyl ether (OBDE), decabrominated diphenyl ether (DBDE), and the non-brominated diphenyl ether did not induce ROS formation at the concentrations tested. DPI (4 microM), an inhibitor of the NADPH oxidase completely inhibited DE-71 induced ROS formation, highlighting a role for NADPH oxidase activation. The protein kinase C inhibitor BIM (0.25 microM) and the selective chelator of intracellular calcium, BAPTA-AM (5 microM), also inhibited NADPH oxidase activation, indicating a calcium-dependent activation of PKC. ROS formation was also inhibited by the tyrosine kinase inhibitor tyrphostin (1 microM), the phospholipase C inhibitor ET-18-OCH3 (5 microM), and the phosphatidylinositol-3 kinase inhibitor LY294002 (25 microM). Alterations in intracellular calcium were measured using fura-2/AM, and a significant increase was measured after exposure to DE-71 both with and without extracellular calcium. The tetra brominated compound BDE-47 also enhanced ROS formation in a concentration dependent manner. The combination of DE-71 with the bacteria-derived N-formyl peptide fMLP and PCB153 induced an additive effect in the lucigenin assay. We suggest that tyrosine kinase mediated activation of PI3K could result in enhanced activation of calcium-dependent PKC by enhanced PLC activity, followed by intracellular calcium release leading to ROS formation in neutrophil granulocytes.
authors.affiliation: Norwegian Defence Research Establishment, Division for Protection, P. O. Box 25, N-2027 Kjeller, Norway. Trine.Reistad@ffi.no
authors.forename: Trine
authors.initials: T
authors.lastname: Reistad
authors.forename: Espen
authors.initials: E
authors.lastname: Mariussen
mesh_terms: D000328:Adult; D002118:Calcium / Q000378:metabolism; D005411:Flame Retardants / Q000633:toxicity*; D055768:Halogenated Diphenyl Ethers; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D019255:NADPH Oxidases / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D010647:Phenyl Ethers / Q000633:toxicity*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D011075:Polybrominated Biphenyls / Q000633:toxicity*; D017382:Reactive Oxygen Species; D016897:Respiratory Burst / Q000187:drug effects*; D015398:Signal Transduction
chemical_list: D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D010647:Phenyl Ethers; D011075:Polybrominated Biphenyls; D017382:Reactive Oxygen Species; D009240:N-Formylmethionine Leucyl-Phenylalanine; C086401:pentabromodiphenyl ether; D019255:NADPH Oxidases; D019869:Phosphatidylinositol 3-Kinases; D002118:Calcium