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Reduced endoglin activity limits cardiac fibrosis and improves survival in heart failure.

ABSTRACT: Heart failure is a major cause of morbidity and mortality worldwide. The ubiquitously expressed cytokine transforming growth factor-?1 (TGF?1) promotes cardiac fibrosis, an important component of progressive heart failure. Membrane-associated endoglin is a coreceptor for TGF?1 signaling and has been studied in vascular remodeling and preeclampsia. We hypothesized that reduced endoglin expression may limit cardiac fibrosis in heart failure.We first report that endoglin expression is increased in the left ventricle of human subjects with heart failure and determined that endoglin is required for TGF?1 signaling in human cardiac fibroblasts using neutralizing antibodies and an siRNA approach. We further identified that reduced endoglin expression attenuates cardiac fibrosis, preserves left ventricular function, and improves survival in a mouse model of pressure-overload-induced heart failure. Prior studies have shown that the extracellular domain of endoglin can be cleaved and released into the circulation as soluble endoglin, which disrupts TGF?1 signaling in endothelium. We now demonstrate that soluble endoglin limits TGF?1 signaling and type I collagen synthesis in cardiac fibroblasts and further show that soluble endoglin treatment attenuates cardiac fibrosis in an in vivo model of heart failure.Our results identify endoglin as a critical component of TGF?1 signaling in the cardiac fibroblast and show that targeting endoglin attenuates cardiac fibrosis, thereby providing a potentially novel therapeutic approach for individuals with heart failure.

SUBMITTER: Kapur NK

PROVIDER: S-EPMC4774533 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

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Reduced endoglin activity limits cardiac fibrosis and improves survival in heart failure.

Kapur Navin K NK Wilson Szuhuei S Yunis Adil A AA Qiao Xiaoying X Mackey Emily E Paruchuri Vikram V Baker Corey C Aronovitz Mark J MJ Karumanchi S Ananth SA Letarte Michelle M Kass David A DA Mendelsohn Michael E ME Karas Richard H RH

Circulation 20120516 22

<h4>Background</h4>Heart failure is a major cause of morbidity and mortality worldwide. The ubiquitously expressed cytokine transforming growth factor-β1 (TGFβ1) promotes cardiac fibrosis, an important component of progressive heart failure. Membrane-associated endoglin is a coreceptor for TGFβ1 signaling and has been studied in vascular remodeling and preeclampsia. We hypothesized that reduced endoglin expression may limit cardiac fibrosis in heart failure.<h4>Methods and results</h4>We first r ...[more]

PMID: 22592898

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Project description:BACKGROUND:Heart failure is a growing cause of morbidity and mortality worldwide. Transforming growth factor beta (TGF-?1) promotes cardiac fibrosis, but also activates counterregulatory pathways that serve to regulate TGF-?1 activity in heart failure. Bone morphogenetic protein 9 (BMP9) is a member of the TGF? family of cytokines and signals via the downstream effector protein Smad1. Endoglin is a TGF? coreceptor that promotes TGF-?1 signaling via Smad3 and binds BMP9 with high affinity. We hypothesized that BMP9 limits cardiac fibrosis by activating Smad1 and attenuating Smad3, and, furthermore, that neutralizing endoglin activity promotes BMP9 activity. METHODS:We examined BMP9 expression and signaling in human cardiac fibroblasts and human subjects with heart failure. We used the transverse aortic constriction-induced model of heart failure to evaluate the functional effect of BMP9 signaling on cardiac remodeling. RESULTS:BMP9 expression is increased in the circulation and left ventricle (LV) of human subjects with heart failure and is expressed by cardiac fibroblasts. Next, we observed that BMP9 attenuates type I collagen synthesis in human cardiac fibroblasts using recombinant human BMP9 and a small interfering RNA approach. In BMP9-/- mice subjected to transverse aortic constriction, loss of BMP9 activity promotes cardiac fibrosis, impairs LV function, and increases LV levels of phosphorylated Smad3 (pSmad3), not pSmad1. In contrast, treatment of wild-type mice subjected to transverse aortic constriction with recombinant BMP9 limits progression of cardiac fibrosis, improves LV function, enhances myocardial capillary density, and increases LV levels of pSmad1, not pSmad3 in comparison with vehicle-treated controls. Because endoglin binds BMP9 with high affinity, we explored the effect of reduced endoglin activity on BMP9 activity. Neutralizing endoglin activity in human cardiac fibroblasts or in wild-type mice subjected to transverse aortic constriction-induced heart failure limits collagen production, increases BMP9 protein levels, and increases levels of pSmad1, not pSmad3. CONCLUSIONS:Our results identify a novel functional role for BMP9 as an endogenous inhibitor of cardiac fibrosis attributable to LV pressure overload and further show that treatment with either recombinant BMP9 or disruption of endoglin activity promotes BMP9 activity and limits cardiac fibrosis in heart failure, thereby providing potentially novel therapeutic approaches for patients with heart failure.

Project description:BACKGROUND:Fibronectin (FN) polymerization is necessary for collagen matrix deposition and is a key contributor to increased abundance of cardiac myofibroblasts (MFs) after cardiac injury. We hypothesized that interfering with FN polymerization or its genetic ablation in fibroblasts would attenuate MF and fibrosis and improve cardiac function after ischemia/reperfusion (I/R) injury. METHODS:Mouse and human MFs were used to assess the impact of the FN polymerization inhibitor (pUR4) in attenuating pathological cellular features such as proliferation, migration, extracellular matrix deposition, and associated mechanisms. To evaluate the therapeutic potential of inhibiting FN polymerization in vivo, wild-type mice received daily intraperitoneal injections of either pUR4 or control peptide (III-11C) immediately after cardiac surgery for 7 consecutive days. Mice were analyzed 7 days after I/R to assess MF markers and inflammatory cell infiltration or 4 weeks after I/R to evaluate long-term effects of FN inhibition on cardiac function and fibrosis. Furthermore, inducible, fibroblast-restricted, FN gene-ablated (Tcf21MerCreMer; Fnflox) mice were used to evaluate cell specificity of FN expression and polymerization in the heart. RESULTS:pUR4 administration on activated MFs reduced FN and collagen deposition into the extracellular matrix and attenuated cell proliferation, likely mediated through decreased c-myc signaling. pUR4 also ameliorated fibroblast migration accompanied by increased ?1 integrin internalization and reduced levels of phosphorylated focal adhesion kinase protein. In vivo, daily administration of pUR4 for 7 days after I/R significantly reduced MF markers and neutrophil infiltration. This treatment regimen also significantly attenuated myocardial dysfunction, pathological cardiac remodeling, and fibrosis up to 4 weeks after I/R. Last, inducible ablation of FN in fibroblasts after I/R resulted in significant functional cardioprotection with reduced hypertrophy and fibrosis. The addition of pUR4 to the FN-ablated mice did not confer further cardioprotection, suggesting that the salutary effects of inhibiting FN polymerization may be mediated largely through effects on FN secreted from the cardiac fibroblast lineage. CONCLUSIONS:Inhibiting FN polymerization or cardiac fibroblast gene expression attenuates pathological properties of MFs in vitro and ameliorates adverse cardiac remodeling and fibrosis in an in vivo model of heart failure. Interfering with FN polymerization may be a new therapeutic strategy for treating cardiac fibrosis and heart failure.

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Reduced endoglin activity limits cardiac fibrosis and improves survival in heart failure.

Publications

Reduced endoglin activity limits cardiac fibrosis and improves survival in heart failure.

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