title: Targeting mitochondrial reactive oxygen species to modulate hypoxia-induced pulmonary hypertension.
abstract: Pulmonary hypertension (PH) is characterized by increased pulmonary vascular remodeling, resistance, and pressures. Reactive oxygen species (ROS) contribute to PH-associated vascular dysfunction. NADPH oxidases (Nox) and mitochondria are major sources of superoxide (O(2)(•-)) and hydrogen peroxide (H(2)O(2)) in pulmonary vascular cells. Hypoxia, a common stimulus of PH, increases Nox expression and mitochondrial ROS (mtROS) production. The interactions between these two sources of ROS generation continue to be defined. We hypothesized that mitochondria-derived O(2)(•-) (mtO(2)(•-)) and H(2)O(2) (mtH(2)O(2)) increase Nox expression to promote PH pathogenesis and that mitochondria-targeted antioxidants can reduce mtROS, Nox expression, and hypoxia-induced PH. Exposure of human pulmonary artery endothelial cells to hypoxia for 72 h increased mtO(2)(•-) and mtH(2)O(2). To assess the contribution of mtO(2)(•-) and mtH(2)O(2) to hypoxia-induced PH, mice that overexpress superoxide dismutase 2 (Tg(hSOD2)) or mitochondria-targeted catalase (MCAT) were exposed to normoxia (21% O(2)) or hypoxia (10% O(2)) for three weeks. Compared with hypoxic control mice, MCAT mice developed smaller hypoxia-induced increases in RVSP, α-SMA staining, extracellular H(2)O(2) (Amplex Red), Nox2 and Nox4 (qRT-PCR and Western blot), or cyclinD1 and PCNA (Western blot). In contrast, Tg(hSOD2) mice experienced exacerbated responses to hypoxia. These studies demonstrate that hypoxia increases mtO(2)(•-) and mtH(2)O(2). Targeting mtH(2)O(2) attenuates PH pathogenesis, whereas targeting mtO(2)(•-) exacerbates PH. These differences in PH pathogenesis were mirrored by RVSP, vessel muscularization, levels of Nox2 and Nox4, proliferation, and H(2)O(2) release. These studies suggest that targeted reductions in mtH(2)O(2) generation may be particularly effective in preventing hypoxia-induced PH.
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Atlanta Veterans Affairs and Emory University Medical Centers, Atlanta, GA 30033, USA.
authors.forename: Sherry E
authors.initials: SE
authors.lastname: Adesina
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Atlanta Veterans Affairs and Emory University Medical Centers, Atlanta, GA 30033, USA.
authors.forename: Bum-Yong
authors.initials: BY
authors.lastname: Kang
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Atlanta Veterans Affairs and Emory University Medical Centers, Atlanta, GA 30033, USA.
authors.forename: Kaiser M
authors.initials: KM
authors.lastname: Bijli
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Atlanta Veterans Affairs and Emory University Medical Centers, Atlanta, GA 30033, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Ma
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Atlanta Veterans Affairs and Emory University Medical Centers, Atlanta, GA 30033, USA.
authors.forename: Juan
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Atlanta Veterans Affairs and Emory University Medical Centers, Atlanta, GA 30033, USA.
authors.forename: Tamara C
authors.initials: TC
authors.lastname: Murphy
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Atlanta Veterans Affairs and Emory University Medical Centers, Atlanta, GA 30033, USA.
authors.forename: C
authors.initials: C
authors.lastname: Michael Hart
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Atlanta Veterans Affairs and Emory University Medical Centers, Atlanta, GA 30033, USA. Electronic address: rsutlif@emory.edu.
authors.forename: Roy L
authors.initials: RL
authors.lastname: Sutliff
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology; D015687:Cell Hypoxia; D049109:Cell Proliferation; D042783:Endothelial Cells / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D006976:Hypertension, Pulmonary / Q000378:metabolism* / Q000473:pathology; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000378:metabolism* / Q000473:pathology; D000074662:NADPH Oxidase 2; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000378:metabolism; D010672:Phenytoin / Q000031:analogs & derivatives / Q000378:metabolism; D011651:Pulmonary Artery / Q000378:metabolism / Q000473:pathology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D000099156:Superoxide Dismutase 2
chemical_list: D000975:Antioxidants; D008562:Membrane Glycoproteins; D000074662:NADPH Oxidase 2; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; D010672:Phenytoin; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D000099156:Superoxide Dismutase 2; C057787:5-(4-hydroxy-3-methoxyphenyl)-5-phenylhydantoin; C488842:Cybb protein, mouse; C422943:Nox4 protein, mouse
keywords: Catalase; Hydrogen peroxide; Mitochondria; NADPH oxidase; Pulmonary hypertension; ROS; SOD2; Superoxide