title: Participation of mitochondrial respiratory complex III in neutrophil activation and lung injury.
abstract: Reactive oxygen species (ROS) produced during mitochondrial activity participate in the regulation of intracellular signaling pathways. However, there is only limited information concerning the role that ROS derived from the mitochondrial respiratory chain play in modulating neutrophil activity and participation in acute inflammatory processes. Because mitochondrial complex III is a major site of ROS formation, we examined whether selective complex III inhibition, through exposure of neutrophils to myxothiazol or antimycin A, would affect LPS-induced activation. Culture of neutrophils with antimycin A or myxothiazol resulted in increased intracellular levels of ROS, including superoxide and hydrogen peroxide (H(2)O(2)). Inhibition of complex III activity reduced LPS-induced degradation of IkappaB-alpha, nuclear accumulation of NF-kappaB, and proinflammatory cytokine production. The effects of antimycin A or myxothiazol appeared to be dependent on generation of H(2)O(2) since addition of pegylated catalase to neutrophils restored LPS-mediated IkappaB-alpha degradation and production of proinflammatory cytokines. Administration of myxothiazol to mice resulted in diminished mitochondrial complex III activity in the lungs and decreased severity of LPS-induced lung injury. These results indicate that inhibition of mitochondrial complex III diminishes Toll-like receptor 4-induced neutrophil activation through a mechanism dependent on H(2)O(2) generation and also reduces the severity of lung injury due to LPS exposure, a pathophysiologic process in which neutrophils play a major role.
authors.affiliation: Department of Medicine, University of Alabama at Birmingham School of Medicine, Birmingham, AL 35294-0012, USA.
authors.forename: Jaroslaw W
authors.initials: JW
authors.lastname: Zmijewski
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Lorne
authors.forename: Sami
authors.initials: S
authors.lastname: Banerjee
authors.forename: Edward
authors.initials: E
authors.lastname: Abraham
mesh_terms: D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis; D014450:Electron Transport Complex III / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004996:Ethidium / Q000031:analogs & derivatives / Q000378:metabolism; D005452:Fluoresceins / Q000378:metabolism; D020672:I-kappa B Proteins / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D055370:Lung Injury / Q000276:immunology* / Q000378:metabolism*; D008297:Male; D008689:Methacrylates / Q000494:pharmacology; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D018375:Neutrophil Activation / Q000187:drug effects / Q000276:immunology*; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology
chemical_list: D016207:Cytokines; D005452:Fluoresceins; D020672:I-kappa B Proteins; D008070:Lipopolysaccharides; D008689:Methacrylates; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D017382:Reactive Oxygen Species; D013844:Thiazoles; C067883:dihydroethidium; C065013:2',7'-dichlorodihydrofluorescein; D000072000:NF-KappaB Inhibitor alpha; D000968:Antimycin A; C030517:myxothiazol; D014450:Electron Transport Complex III; D004996:Ethidium