title: Aortic valve sclerosis in mice deficient in endothelial nitric oxide synthase.
abstract: Risk factors for fibrocalcific aortic valve disease (FCAVD) are associated with systemic decreases in bioavailability of endothelium-derived nitric oxide (EDNO). In patients with bicuspid aortic valve (BAV), vascular expression of endothelial nitric oxide synthase (eNOS) is decreased, and eNOS(-/-) mice have increased prevalence of BAV. The goal of this study was to test the hypotheses that EDNO attenuates profibrotic actions of valve interstitial cells (VICs) in vitro and that EDNO deficiency accelerates development of FCAVD in vivo. As a result of the study, coculture of VICs with aortic valve endothelial cells (vlvECs) significantly decreased VIC activation, a critical early phase of FCAVD. Inhibition of VIC activation by vlvECs was attenuated by N(G)-nitro-l-arginine methyl ester or indomethacin. Coculture with vlvECs attenuated VIC expression of matrix metalloproteinase-9, which depended on stiffness of the culture matrix. Coculture with vlvECs preferentially inhibited collagen-3, compared with collagen-1, gene expression. BAV occurred in 30% of eNOS(-/-) mice. At age 6 mo, collagen was increased in both bicuspid and trileaflet eNOS(-/-) aortic valves, compared with wild-type valves. At 18 mo, total collagen was similar in eNOS(-/-) and wild-type mice, but collagen-3 was preferentially increased in eNOS(-/-) mice. Calcification and apoptosis were significantly increased in BAV of eNOS(-/-) mice at ages 6 and 18 mo. Remarkably, these histological changes were not accompanied by physiologically significant valve stenosis or regurgitation. In conclusion, coculture with vlvECs inhibits specific profibrotic VIC processes. In vivo, eNOS deficiency produces fibrosis in both trileaflet and BAVs but produces calcification only in BAVs.
authors.affiliation: Division of Cardiovascular Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa;
authors.forename: Ramzi N
authors.initials: RN
authors.lastname: El Accaoui
authors.forename: Sarah T
authors.initials: ST
authors.lastname: Gould
authors.forename: Georges P
authors.initials: GP
authors.lastname: Hajj
authors.forename: Yi
authors.initials: Y
authors.lastname: Chu
authors.forename: Melissa K
authors.initials: MK
authors.lastname: Davis
authors.forename: Diane C
authors.initials: DC
authors.lastname: Kraft
authors.forename: Donald D
authors.initials: DD
authors.lastname: Lund
authors.forename: Robert M
authors.initials: RM
authors.lastname: Brooks
authors.forename: Hardik
authors.initials: H
authors.lastname: Doshi
authors.forename: Kathy A
authors.initials: KA
authors.lastname: Zimmerman
authors.forename: William
authors.initials: W
authors.lastname: Kutschke
authors.forename: Kristi S
authors.initials: KS
authors.lastname: Anseth
authors.forename: Donald D
authors.initials: DD
authors.lastname: Heistad
authors.forename: Robert M
authors.initials: RM
authors.lastname: Weiss
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D017209:Apoptosis; D000082882:Bicuspid Aortic Valve Disease; D002114:Calcinosis / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D002478:Cells, Cultured; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D024061:Collagen Type III / Q000235:genetics / Q000378:metabolism; D006330:Heart Defects, Congenital / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D006349:Heart Valve Diseases / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D056885:Interstitial Cells of Cajal / Q000378:metabolism / Q000473:pathology; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D052250:Nitric Oxide Synthase Type III / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D012598:Sclerosis / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D013552:Swine
chemical_list: D024042:Collagen Type I; D024061:Collagen Type III; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D020780:Matrix Metalloproteinase 9
keywords: aortic valve sclerosis; bicuspid aortic valve; endothelial nitric oxide synthase