Browsing by Subject "Cardiac fibrosis"

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    AMPKα1 deletion in myofibroblasts exacerbates post-myocardial infarction fibrosis by a connexin 43 mechanism
    (SpringerLink, 2021-02-09) Dufeys, Cécile; Daskalopoulos, Evangelos-Panagiotis; Castanares-Zapatero, Diego; Conway, Simon J.; Ginion, Audrey; Bouzin, Caroline; Ambroise, Jérôme; Bearzatto, Bertrand; Gala, Jean-Luc; Heymans, Stephane; Papageorgiou, Anna-Pia; Vinckier, Stefan; Cumps, Julien; Balligand, Jean-Luc; Vanhaverbeke, Maarten; Sinnaeve, Peter; Janssens, Stefan; Bertrand, Luc; Beauloye, Christophe; Horman, Sandrine; Pediatrics, School of Medicine
    We have previously demonstrated that systemic AMP-activated protein kinase α1 (AMPKα1) invalidation enhanced adverse LV remodelling by increasing fibroblast proliferation, while myodifferentiation and scar maturation were impaired. We thus hypothesised that fibroblastic AMPKα1 was a key signalling element in regulating fibrosis in the infarcted myocardium and an attractive target for therapeutic intervention. The present study investigates the effects of myofibroblast (MF)-specific deletion of AMPKα1 on left ventricular (LV) adaptation following myocardial infarction (MI), and the underlying molecular mechanisms. MF-restricted AMPKα1 conditional knockout (cKO) mice were subjected to permanent ligation of the left anterior descending coronary artery. cKO hearts exhibit exacerbated post-MI adverse LV remodelling and are characterised by exaggerated fibrotic response, compared to wild-type (WT) hearts. Cardiac fibroblast proliferation and MF content significantly increase in cKO infarcted hearts, coincident with a significant reduction of connexin 43 (Cx43) expression in MFs. Mechanistically, AMPKα1 influences Cx43 expression by both a transcriptional and a post-transcriptional mechanism involving miR-125b-5p. Collectively, our data demonstrate that MF-AMPKα1 functions as a master regulator of cardiac fibrosis and remodelling and might constitute a novel potential target for pharmacological anti-fibrotic applications.
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    Therapeutic Targeting of Vascular Remodeling and Right Heart Failure in Pulmonary Arterial Hypertension with a HIF-2α Inhibitor
    (American Thoracic Society, 2018-12-01) Dai, Zhiyu; Dai, Zhiyu; Zhu, Maggie M.; Peng, Yi; Machireddy, Narsa; Evans, Colin E.; Machado, Roberto; Zhang, Xianming; Zhao, You-Yang; Medicine, School of Medicine
    Rationale: Pulmonary arterial hypertension (PAH) is a devastating disease characterized by progressive vasoconstriction and obliterative vascular remodeling that leads to right heart failure (RHF) and death. Current therapies do not target vascular remodeling and RHF, and result in only modest improvement of morbidity and mortality. Objectives: To determine whether targeting HIF-2α (hypoxia-inducible factor-2α) with a HIF-2α–selective inhibitor could reverse PAH and RHF in various rodent PAH models. Methods: HIF-2α and its downstream genes were evaluated in lung samples and pulmonary arterial endothelial cells and smooth muscle cells from patients with idiopathic PAH as well as various rodent PAH models. A HIF-2α–selective inhibitor was used in human lung microvascular endothelial cells and in Egln1Tie2Cre mice, and in Sugen 5416/hypoxia- or monocrotaline-exposed rats. Measurements and Main Results: Upregulation of HIF-2α and its target genes was observed in lung tissues and isolated pulmonary arterial endothelial cells from patients with idiopathic PAH and three distinct rodent PAH models. Pharmacological inhibition of HIF-2α by the HIF-2α translation inhibitor C76 (compound 76) reduced right ventricular systolic pressure and right ventricular hypertrophy and inhibited RHF and fibrosis as well as obliterative pulmonary vascular remodeling in Egln1Tie2Cre mice and Sugen 5416/hypoxia PAH rats. Treatment of monocrotaline-exposed PAH rats with C76 also reversed right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary vascular remodeling; prevented RHF; and promoted survival. Conclusions: These findings demonstrate that pharmacological inhibition of HIF-2α is a promising novel therapeutic strategy for the treatment of severe vascular remodeling and right heart failure in patients with PAH.