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Comparison of Macitentan and Bosentan on Right Ventricular Remodeling in a Rat Model of Non-vasoreactive Pulmonary Hypertension.

ABSTRACT: We compared the efficacy of macitentan, a novel dual endothelin A/endothelin B receptor antagonist, with that of another dual endothelin receptor antagonist, bosentan, in a rat model of non-vasoreactive pulmonary hypertension (PH) with particular emphasis on right ventricular (RV) remodeling.Unlike monocrotaline or hypoxic/sugen rats, bleomycin-treated rats presented a non-vasoreactive PH characterized by the absence of pulmonary dilatation to adenosine. We therefore chose the bleomycin rat model to compare the effects of the maximally effective doses of macitentan and bosentan on pulmonary vascular and RV remodeling. Macitentan (100 mg·kg(-1)·d(-1)), but not bosentan (300 mg·kg(-1)·d(-1)), significantly prevented pulmonary vascular remodeling, RV hypertrophy, and cardiomyocyte diameter increase. Cardiac protection by macitentan was associated with a significant attenuation of genes related to cell hypertrophy and extracellular matrix remodeling. Microautoradiography and high performance liquid chromatography analysis showed greater distribution of macitentan than bosentan in the RV and pulmonary tissue.Macitentan was more efficacious than bosentan in preventing the development of pulmonary and RV hypertrophies in a model of non-vasoreactive PH. Greater ability to distribute into the tissue could contribute to the greater structural improvement by macitentan compared with bosentan.

SUBMITTER: Iglarz M

PROVIDER: S-EPMC4632117 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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Comparison of Macitentan and Bosentan on Right Ventricular Remodeling in a Rat Model of Non-vasoreactive Pulmonary Hypertension.

Iglarz Marc M Landskroner Kyle K Bauer Yasmina Y Vercauteren Magali M Rey Markus M Renault Berengère B Studer Rolf R Vezzali Enrico E Freti Diego D Hadana Hakim H Schläpfer Manuela M Cattaneo Christophe C Bortolamiol Céline C Weber Edgar E Whitby Brian R BR Delahaye Stéphane S Wanner Daniel D Steiner Pauline P Nayler Oliver O Hess Patrick P Clozel Martine M

Journal of cardiovascular pharmacology 20151101 5

<h4>Aims</h4>We compared the efficacy of macitentan, a novel dual endothelin A/endothelin B receptor antagonist, with that of another dual endothelin receptor antagonist, bosentan, in a rat model of non-vasoreactive pulmonary hypertension (PH) with particular emphasis on right ventricular (RV) remodeling.<h4>Methods and results</h4>Unlike monocrotaline or hypoxic/sugen rats, bleomycin-treated rats presented a non-vasoreactive PH characterized by the absence of pulmonary dilatation to adenosine. ...[more]

PMID: 26230396

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Project description:Even though pulmonary arterial hypertension (PAH) remains an incurable disease, the combination of PAH-specific therapies allowed evolving from symptom-based strategies to others aiming to move patients to low-risk conditions. Endothelin-1 (ET-1) receptor antagonists emerged as specific-PAH drugs that can be used in combination with other specific therapies. This work aimed to perform a prospective clinical assessment of patients with PAH that switched from bosentan to macitentan (POTENT), due to inadequate response. POTENT is a prospective, open-label, single-arm, uncontrolled study including PAH patients from our ongoing SAUDIPH registry. It enrolled 50 PAH patients divided as follows: idiopathic/heritable pulmonary arterial hypertension (I/HPAH); n = 24; PAH associated with congenital heart disease, n = 19; PAH associated with connective tissue diseases, n = 5; and pulmonary veno-occlusive disease and/or pulmonary capillary haemangiomatosis (PVOD/PCH), n = 2. At baseline, most patients were in World Health Organization Functional Class (WHO FC) II/III (52.0%). After switching to macitentan, patients were more likely to be in WHO FC I/II (78%) and 22% of the overall cohort moved to a lower risk condition, with three low risk stratification parameters. Mean 6-min walking distance increased about 34 m after 12 months, with a significant mean change over time (12.63 ± 11.69 at month 3 vs. 40.75 ± 12.57 at month 12, p = 0.002). Most haemodynamic parameters decreased over time, with corresponding negative mean changes (p < 0.001). The safety of macitentan was confirmed by the absence of anaemia and liver injury; clinical worsening was observed only in a small group of patients. In general, macitentan might be a valid alternative to bosentan in PAH stable patients on combination therapy with insufficient clinical response, and presenting intermediate and high-risk parameters. We anticipate that studying this strategy in PAH subgroups would further clarify its potential and limitations.

Project description:Pulmonary arterial hypertension (PAH) imposes substantial pressure overload on the right ventricular free wall (RVFW), leading to myofiber hypertrophy and remodeling of its collagen fiber architecture. The transmural nature of these adaptations and their effects on the macroscopic mechanical behavior of the RVFW remain largely unexplored. In the present work, we extended our constitutive model for RVFW myocardium to investigate the transmural mechanical and structural remodeling post-PAH. Recent murine experimental studies provided us with comprehensive histomorphological and biaxial mechanical data for viable, passive myocardium for normal and post hypertensive cases. Multiple fiber-level remodeling events were found to be localized in the midwall region (40% < depth < 60%): (i) reorientation and alignment of both myo- and collagen fibers towards longitudinal (apex-to-outflow tract) direction, (ii) substantial increase in the rate of the recruitment of collagen fibers with strain, and (iii) a corresponding increase in the mechanical interactions between the collagen and myofibers. These adaptations suggest a denser and more fibrous connective tissue in the midwall region, and led to a substantially stiffer mechanical response along the longitudinal direction in post-PAH tissues. Moreover, using a Laplace-type mechanical equilibrium analysis of the right ventricle to approximate the wall stress state, we estimated that the longitudinal component of stress remained higher in the hypertensive state while the circumferential component approximately maintained homeostasis values. This result was consistent with our observation from the fiber- and tissue-level remodeling that longitudinally oriented collagen fibers, localized in the midwall region, dominated the remodeling process. The findings of this study highlight the need for more integrated cellular-tissue-organ analysis to better understand the remodeling events during PAH and design interventions.

Project description:BackgroundRight ventricular (RV) dysfunction is a significant prognostic determinant of morbidity and mortality in pulmonary arterial hypertension (PAH). Despite the importance of RV function in PAH, the underlying molecular mechanisms of RV dysfunction secondary to PAH remain unclear. We aim to identify and compare molecular determinants of RV failure using RNA sequencing of RV tissue from 2 clinically relevant animal models of PAH.MethodsWe performed RNA sequencing on RV from rats treated with monocrotaline or Sugen with hypoxia/normoxia. PAH and RV failure were confirmed by catheterization and echocardiography. We validated the RV transcriptome results using quantitative real-time polymerase chain reaction, immunofluorescence, and Western blot. Immunohistochemistry and immunofluorescence were performed on human RV tissue from control (n=3) and PAH-induced RV failure patients (n=5).ResultsWe identified similar transcriptomic profiles of RV from monocrotaline- and Sugen with hypoxia-induced RV failure. Pathway analysis showed genes enriched in epithelial-to-mesenchymal transition, inflammation, and metabolism. Histological staining of human RV tissue from patients with RV failure secondary to PAH revealed significant RV fibrosis and endothelial-to-mesenchymal transition, as well as elevated cellular communication network factor 2 (top gene implicated in epithelial-to-mesenchymal transition/endothelial-to-mesenchymal transition) expression in perivascular areas compared with normal RV.ConclusionsTranscriptomic signature of RV failure in monocrotaline and Sugen with hypoxia models showed similar gene expressions and biological pathways. We provide translational relevance of this transcriptomic signature using RV from patients with PAH to demonstrate evidence of epithelial-to-mesenchymal transition/endothelial-to-mesenchymal transition and protein expression of cellular communication network factor 2 (CTGF [connective tissue growth factor]). Targeting specific molecular mechanisms responsible for RV failure in monocrotaline and Sugen with hypoxia models may identify novel therapeutic strategies for PAH-associated RV failure.

Project description:BackgroundThe cardioprotective properties of sevoflurane have been reported in studies of the left ventricle. However, whether this volatile anesthetic would also be beneficial for pulmonary vascular remodeling and associated right ventricular hypertrophy (RVH) remained to be explored. Here, we investigated the potential benefit of sevoflurane to right heart function in experimental pulmonary arterial hypertension (PAH).MethodsAdult Wistar rats received one dose peritoneal injection of monocrotaline (MCT, 60 mg/kg) or the equal volume of normal saline. Two weeks later, rats were treated with sevoflurane or sham exposure. PAH status and cardiac function were assessed by echocardiography weekly, and the body weight (BW) was monitored every week. After 6 weeks of exercise, Fulton's index calculation, histological observation, IL-6 and TNF-α immunohistochemical analyses, evaluation of MDA, SOD and GSH-Px levels and NF-κB and MAPK active determination were performed in lung and RV tissue samples.ResultsMCT induced pulmonary vascular remodeling, RVH, increased Fulton's index (P<0.01), and right ventricular failure (RVF) in rats. Animals inhaled sevoflurane had an increased cardiac output (P<0.05) and lower incidence of RVF (P<0.05). Also, these animals had a reduced RVEDD, RVWTd and PAID (P<0.05), increased PV (P<0.05), reduced wall thickness and vascular wall area of pulmonary small vascular (vascular external diameter 50-150 um) (P<0.01), reduced RV fibrosis, and increased RV cardiomyocyte area (P<0.01). Furthermore, sevoflurane reduced IL-6 and TNF-α expression in lungs and heart (P<0.01), decreased level of MDA (P<0.01) and increased activity of SOD and GSH-Px (P<0.01). In addition, it decreased the activities of NF-κB and MAPK pathways (P<0.01).ConclusionSevoflurane reduces pulmonary vascular remodeling and RVH in PAH induced by MCT in rats. This effect is likely due to down-regulation of inflammatory factors IL-6 and TNF-α, reduced level of oxidative stress and the inhibition of NF-κB and MAPK pathways.

Dataset Information

Comparison of Macitentan and Bosentan on Right Ventricular Remodeling in a Rat Model of Non-vasoreactive Pulmonary Hypertension.

Publications

Comparison of Macitentan and Bosentan on Right Ventricular Remodeling in a Rat Model of Non-vasoreactive Pulmonary Hypertension.

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