TGF-β signalling and reactive oxygen species drive fibrosis and matrix remodelling in myxomatous mitral valves

Michael A. Hagler, Thomas M. Hadley, Heyu Zhang, Kashish Mehra, Carolyn M. Roos, Hartzell V Schaff, Rakesh M. Suri, Jordan D Miller

Research output: Contribution to journalArticle

65 Citations (Scopus)

Abstract

AimsMyxomatous mitral valve disease (MMVD) is associated with leaflet thickening, fibrosis, matrix remodelling, and leaflet prolapse. Molecular mechanisms contributing to MMVD, however, remain poorly understood. We tested the hypothesis that increased transforming growth factor-β (TGF-β) signalling and reactive oxygen species (ROS) are major contributors to pro-fibrotic gene expression in human and mouse mitral valves.Methods and resultsUsing qRT-PCR, we found that increased expression of TGF-β1 in mitral valves from humans with MMVD (n = 24) was associated with increased expression of connective tissue growth factor (CTGF) and matrix metalloproteinase 2 (MMP2). Increased levels of phospho-SMAD2/3 (western blotting) and expression of SMAD-specific E3 ubiquitin-protein ligases (SMURF) 1 and 2 (qRT-PCR) suggested that TGF-β1 signalling occurred through canonical signalling cascades. Oxidative stress (dihydroethidium staining) was increased in human MMVD tissue and associated with increases in NAD(P)H oxidase catalytic subunits (Nox) 2 and 4, occurring despite increases in superoxide dismutase 1 (SOD1). In mitral valves from SOD1-deficient mice, expression of CTGF, MMP2, Nox2, and Nox4 was significantly increased, suggesting that ROS can independently activate pro-fibrotic and matrix remodelling gene expression patterns. Furthermore, treatment of mouse mitral valve interstitial cells with cell permeable antioxidants attenuated TGF-β1-induced pro-fibrotic and matrix remodelling gene expression in vitro.ConclusionActivation of canonical TGF-β signalling is a major contributor to fibrosis and matrix remodelling in MMVD, and is amplified by increases in oxidative stress. Treatments aimed at reducing TGF-β activation and oxidative stress in early MMVD may slow progression of MMVD.

Original languageEnglish (US)
Pages (from-to)175-184
Number of pages10
JournalCardiovascular Research
Volume99
Issue number1
DOIs
StatePublished - Jul 1 2013

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Transforming Growth Factors
Mitral Valve
Reactive Oxygen Species
Fibrosis
Oxidative Stress
Matrix Metalloproteinase 2
Gene Expression
Connective Tissue Growth Factor
Polymerase Chain Reaction
Ubiquitin-Protein Ligases
NADPH Oxidase
Prolapse
Catalytic Domain
Antioxidants
Western Blotting
Staining and Labeling

Keywords

  • Antioxidants
  • Cardiovascular surgery
  • Mitral valve
  • Regurgitation
  • Valves

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)
  • Physiology

Cite this

TGF-β signalling and reactive oxygen species drive fibrosis and matrix remodelling in myxomatous mitral valves. / Hagler, Michael A.; Hadley, Thomas M.; Zhang, Heyu; Mehra, Kashish; Roos, Carolyn M.; Schaff, Hartzell V; Suri, Rakesh M.; Miller, Jordan D.

In: Cardiovascular Research, Vol. 99, No. 1, 01.07.2013, p. 175-184.

Research output: Contribution to journalArticle

Hagler, Michael A. ; Hadley, Thomas M. ; Zhang, Heyu ; Mehra, Kashish ; Roos, Carolyn M. ; Schaff, Hartzell V ; Suri, Rakesh M. ; Miller, Jordan D. / TGF-β signalling and reactive oxygen species drive fibrosis and matrix remodelling in myxomatous mitral valves. In: Cardiovascular Research. 2013 ; Vol. 99, No. 1. pp. 175-184.
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T1 - TGF-β signalling and reactive oxygen species drive fibrosis and matrix remodelling in myxomatous mitral valves

AU - Hagler, Michael A.

AU - Hadley, Thomas M.

AU - Zhang, Heyu

AU - Mehra, Kashish

AU - Roos, Carolyn M.

AU - Schaff, Hartzell V

AU - Suri, Rakesh M.

AU - Miller, Jordan D

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N2 - AimsMyxomatous mitral valve disease (MMVD) is associated with leaflet thickening, fibrosis, matrix remodelling, and leaflet prolapse. Molecular mechanisms contributing to MMVD, however, remain poorly understood. We tested the hypothesis that increased transforming growth factor-β (TGF-β) signalling and reactive oxygen species (ROS) are major contributors to pro-fibrotic gene expression in human and mouse mitral valves.Methods and resultsUsing qRT-PCR, we found that increased expression of TGF-β1 in mitral valves from humans with MMVD (n = 24) was associated with increased expression of connective tissue growth factor (CTGF) and matrix metalloproteinase 2 (MMP2). Increased levels of phospho-SMAD2/3 (western blotting) and expression of SMAD-specific E3 ubiquitin-protein ligases (SMURF) 1 and 2 (qRT-PCR) suggested that TGF-β1 signalling occurred through canonical signalling cascades. Oxidative stress (dihydroethidium staining) was increased in human MMVD tissue and associated with increases in NAD(P)H oxidase catalytic subunits (Nox) 2 and 4, occurring despite increases in superoxide dismutase 1 (SOD1). In mitral valves from SOD1-deficient mice, expression of CTGF, MMP2, Nox2, and Nox4 was significantly increased, suggesting that ROS can independently activate pro-fibrotic and matrix remodelling gene expression patterns. Furthermore, treatment of mouse mitral valve interstitial cells with cell permeable antioxidants attenuated TGF-β1-induced pro-fibrotic and matrix remodelling gene expression in vitro.ConclusionActivation of canonical TGF-β signalling is a major contributor to fibrosis and matrix remodelling in MMVD, and is amplified by increases in oxidative stress. Treatments aimed at reducing TGF-β activation and oxidative stress in early MMVD may slow progression of MMVD.

AB - AimsMyxomatous mitral valve disease (MMVD) is associated with leaflet thickening, fibrosis, matrix remodelling, and leaflet prolapse. Molecular mechanisms contributing to MMVD, however, remain poorly understood. We tested the hypothesis that increased transforming growth factor-β (TGF-β) signalling and reactive oxygen species (ROS) are major contributors to pro-fibrotic gene expression in human and mouse mitral valves.Methods and resultsUsing qRT-PCR, we found that increased expression of TGF-β1 in mitral valves from humans with MMVD (n = 24) was associated with increased expression of connective tissue growth factor (CTGF) and matrix metalloproteinase 2 (MMP2). Increased levels of phospho-SMAD2/3 (western blotting) and expression of SMAD-specific E3 ubiquitin-protein ligases (SMURF) 1 and 2 (qRT-PCR) suggested that TGF-β1 signalling occurred through canonical signalling cascades. Oxidative stress (dihydroethidium staining) was increased in human MMVD tissue and associated with increases in NAD(P)H oxidase catalytic subunits (Nox) 2 and 4, occurring despite increases in superoxide dismutase 1 (SOD1). In mitral valves from SOD1-deficient mice, expression of CTGF, MMP2, Nox2, and Nox4 was significantly increased, suggesting that ROS can independently activate pro-fibrotic and matrix remodelling gene expression patterns. Furthermore, treatment of mouse mitral valve interstitial cells with cell permeable antioxidants attenuated TGF-β1-induced pro-fibrotic and matrix remodelling gene expression in vitro.ConclusionActivation of canonical TGF-β signalling is a major contributor to fibrosis and matrix remodelling in MMVD, and is amplified by increases in oxidative stress. Treatments aimed at reducing TGF-β activation and oxidative stress in early MMVD may slow progression of MMVD.

KW - Antioxidants

KW - Cardiovascular surgery

KW - Mitral valve

KW - Regurgitation

KW - Valves

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