title: Selective depletion of vascular EC-SOD augments chronic hypoxic pulmonary hypertension.
abstract: Excess superoxide has been implicated in pulmonary hypertension (PH). We previously found lung overexpression of the antioxidant extracellular superoxide dismutase (EC-SOD) attenuates PH and pulmonary artery (PA) remodeling. Although comprising a small fraction of total SOD activity in most tissues, EC-SOD is abundant in arteries. We hypothesize that the selective loss of vascular EC-SOD promotes hypoxia-induced PH through redox-sensitive signaling pathways. EC-SOD(loxp/loxp) × Tg(cre/SMMHC) mice (SMC EC-SOD KO) received tamoxifen to conditionally deplete smooth muscle cell (SMC)-derived EC-SOD. Mice were exposed to hypobaric hypoxia for 35 days, and PH was assessed by right ventricular systolic pressure measurements and right ventricle hypertrophy. Vascular remodeling was evaluated by morphometric analysis and two-photon microscopy for collagen. We examined cGMP content and soluble guanylate cyclase expression and activity in lung, lung phosphodiesterase 5 (PDE5) expression and activity, and expression of endothelial nitric oxide synthase and GTP cyclohydrolase-1 (GTPCH-1), the rate-limiting enzyme in tetrahydrobiopterin synthesis. Knockout of SMC EC-SOD selectively decreased PA EC-SOD without altering total lung EC-SOD. PH and vascular remodeling induced by chronic hypoxia was augmented in SMC EC-SOD KO. Depletion of SMC EC-SOD did not impact content or activity of lung soluble guanylate cyclase or PDE5, yet it blunted the hypoxia-induced increase in cGMP. Although total eNOS was not altered, active eNOS and GTPCH-1 decreased with hypoxia only in SMC EC-SOD KO. We conclude that the localized loss of PA EC-SOD augments chronic hypoxic PH. In addition to oxidative inactivation of NO, deletion of EC-SOD seems to reduce eNOS activity, further compromising pulmonary vascular function.
authors.affiliation: Department of Pediatrics, University of Colorado, Aurora, Colorado; Department of Cardiovascular Pulmonary Research, University of Colorado, Aurora, Colorado; eva.grayck@ucdenver.edu.
authors.forename: Eva
authors.initials: E
authors.lastname: Nozik-Grayck
authors.affiliation: Department of Pediatrics, University of Colorado, Aurora, Colorado;
authors.forename: Crystal
authors.initials: C
authors.lastname: Woods
authors.affiliation: Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois; and.
authors.forename: Joann M
authors.initials: JM
authors.lastname: Taylor
authors.affiliation: Department of Pediatrics, University of Colorado, Aurora, Colorado; Department of Bioengineering, University of Colorado, Aurora, Colorado;
authors.forename: Richard K P
authors.initials: RK
authors.lastname: Benninger
authors.affiliation: Department of Pediatrics, University of Colorado, Aurora, Colorado;
authors.forename: Richard D
authors.initials: RD
authors.lastname: Johnson
authors.affiliation: Department of Pediatrics, University of Colorado, Aurora, Colorado; Department of Cardiovascular Pulmonary Research, University of Colorado, Aurora, Colorado;
authors.forename: Leah R
authors.initials: LR
authors.lastname: Villegas
authors.affiliation: Department of Pediatrics, University of Colorado, Aurora, Colorado; Department of Cardiovascular Pulmonary Research, University of Colorado, Aurora, Colorado;
authors.forename: Kurt R
authors.initials: KR
authors.lastname: Stenmark
authors.affiliation: Department of Medicine, Vanderbilt University, Nashville, Tennessee.
authors.forename: David G
authors.initials: DG
authors.lastname: Harrison
authors.affiliation: Department of Medicine, Vanderbilt University, Nashville, Tennessee.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Majka
authors.affiliation: Department of Cardiovascular Pulmonary Research, University of Colorado, Aurora, Colorado;
authors.forename: David
authors.initials: D
authors.lastname: Irwin
authors.affiliation: Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois; and.
authors.forename: Kathryn N
authors.identifier: http://orcid.org/0000-0002-8604-7023
authors.initials: KN
authors.lastname: Farrow
mesh_terms: D000818:Animals; D001794:Blood Pressure; D006152:Cyclic GMP / Q000096:biosynthesis; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5 / Q000096:biosynthesis; D004965:Estrogen Antagonists / Q000494:pharmacology; D006136:GTP Cyclohydrolase / Q000096:biosynthesis; D006162:Guanylate Cyclase / Q000096:biosynthesis; D006976:Hypertension, Pulmonary / Q000628:therapy*; D017380:Hypertrophy, Right Ventricular / Q000503:physiopathology; D000860:Hypoxia / Q000628:therapy*; D008168:Lung / Q000378:metabolism / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D052250:Nitric Oxide Synthase Type III / Q000096:biosynthesis; D011651:Pulmonary Artery / Q000473:pathology; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis; D015398:Signal Transduction; D000071756:Soluble Guanylyl Cyclase; D013482:Superoxide Dismutase / Q000235:genetics*; D013629:Tamoxifen / Q000494:pharmacology
chemical_list: D004965:Estrogen Antagonists; D018160:Receptors, Cytoplasmic and Nuclear; D013629:Tamoxifen; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; C499090:Sod3 protein, mouse; D013482:Superoxide Dismutase; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; C517382:Pde5a protein, mouse; D006136:GTP Cyclohydrolase; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase; D006152:Cyclic GMP
keywords: endothelial nitric oxide synthase; extracellular superoxide dismutase; guanosine 3′,5′-cyclic monophosphate; guanylate cyclase; hypoxia; nitric oxide synthase; phosphodiesterase; pulmonary vascular remodeling