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Clinical symptoms of right ventricular failure in experimental chronic pressure load are associated with progressive diastolic dysfunction

ABSTRACT: Right ventricular failure (RVF) due to pressure load is a major cause of death in congenital heart diseases and pulmonary hypertension. The mechanisms of RVF are yet unknown. Research is hampered by the lack of a good RVF model. Our aim was to study the pathophysiology of RVF in a rat model of chronic pressure load. Wistar rats (n=19) were subjected to pulmonary artery banding (PAB, 1.1mm) or sham surgery (CON). All PAB rats developed RVF (reduced cardiac output, RV stroke volume, TAPSE, increased end diastolic pressure, all p<0.05 vs. CON) but clinical symptoms of RVF (inactivity, ruffled fur, dyspnea, ascites) necessitating termination ensued in a subset (5/12) of rats (RVF+) after a period of 52±5 days. Rats with RVF+ had significantly worse RV function and pericardial effusion and liver congestion compared to RVF rats without symptoms (all p<0.05), despite similar pressure load (p=NS RVF vs. RVF+). Chronic pulmonary artery banding invariably leads to RV failure in rats, and a subset transitions to advanced clinical RVF. RVF is characterized by enhanced contractility, progressive diastolic dysfunction and derangement of energy metabolism, thus improving diastolic function and targeting RV metabolism may be the keys to treating RVF.

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE46863 | GEO | 2014/12/08

SECONDARY ACCESSION(S): PRJNA202872

REPOSITORIES: GEO

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Project description:Background: Right ventricular (RV) and left ventricular (LV) myocardium differ in their response to pressure-overload hypertrophy (POH). In this report we use microarray and proteomic analyses to identify pathways modulated by LV-, and RV-POH in the immature heart. Methods: Newborn New Zealand White rabbits underwent banding of the descending thoracic aorta (LV-POH; n=6). RV-POH was achieved by banding the pulmonary artery (n=6). Sham–control animals (SC; n=6 each) were sham-manipulated. Following 4 (LV-POH) and 6 weeks (RV-POH) recovery, the hearts were removed and matched sample RNA and proteins were isolated for microarray and proteomic analysis. Results: There was no difference in body weight in RV-, LV-POH vs. SC but there was a significant increase vs. SC in RV (3.2±0.8g vs. 1.2±0.3g; P<0.01) and LV weight (7.08±0.6g vs. 4.02±0.2g; P<0.01). Fractional area change (RV-POH) and shortening fraction (LV-POH) decreased significantly (23±6 vs. 47±6 and 21±4 vs.44±2, respectively, P<0.01). Microarray analysis demonstrated that LV-POH enriched pathways for oxidative phosphorylation, mitochondria energy pathways, actin, ILK, hypoxia, calcium and protein kinase-A signalling. RV-POH enriched pathways for cardiac oxidative phosphorylation. Proteomic analysis revealed 19 proteins were uniquely expressed in LV-POH vs. SC. Functional annotation clustering analysis indicated significant enrichment for the mitochondrion, cellular macromolecular complex assembly and oxidative phosphorylation. RV-POH had 15 uniquely expressed proteins vs. SC. Functional annotation clustering analysis indicated significant enrichment in structural constituents of muscle, cardiac muscle tissue development and calcium handling. Conclusion: Our results identify unique transcript and protein expression profiles in LV, RV-POH and provide new insight into the biological basis of ventricular specific hypertrophy. 3 different conditions: PAB-RV vs. Sham-control RV, PAB-RV [test] vs. PAB-LV [control], AOB-LV vs. Sham-control LV.

Project description:Abstract: Right ventricular failure (RVF) remains the leading cause of death in pulmonary arterial hypertension (PAH). We investigated the transcriptomic signature of RVF in hemodynamically well-phenotyped monocrotaline (MCT)-treated, male, Sprague-Dawley rats with severe PAH and decompensated RVF (increased right ventricular (RV) end diastolic volume (EDV), decreased cardiac output (CO), tricuspid annular plane systolic excursion (TAPSE) and ventricular-arterial decoupling). RNA sequencing revealed 2547 differentially regulated transcripts in MCT-RVF RVs. Multiple enriched gene ontology (GO) terms converged on mitochondria/metabolism, fibrosis, inflammation, and angiogenesis. The mitochondrial transcriptomic pathway is the most affected in RVF, with 413 dysregulated genes. Downregulated genes included tfam (−0.45-fold), suggesting impaired mitochondrial biogenesis, Cyp2e1 (−3.8-fold), a monooxygenase which when downregulated increases oxidative stress, dehydrogenase/reductase 7C (Dhrs7c) (−2.8-fold), consistent with excessive autonomic activation, and polypeptide N-acetyl-galactose-aminyl-transferase 13 (Galnt13), a known pulmonary hypertension (PH) biomarker (−2.7-fold). The most up-regulated gene encodes Periostin (Postn; 4.5-fold), a matricellular protein relevant to fibrosis. Other dysregulated genes relevant to fibrosis include latent-transforming growth factor beta-binding protein 2 (Ltbp2), thrombospondin4 (Thbs4). We also identified one dysregulated gene relevant to all disordered transcriptomic pathways, Annexin A1. This anti-inflammatory, phospholipid-binding mediator, is a putative target for therapy in RVF-PAH. Comparison of expression profiles in the MCT-RV with published microarray data from the RV of pulmonary artery-banded mice and humans with bone morphogenetic protein receptor type 2 (BMPR2)-mutations PAH reveals substantial conservation of gene dysregulation, which may facilitate clinical translation of preclinical therapeutic and biomarkers studies. Transcriptomics reveals the molecular fingerprint of RVF to be heavily characterized by mitochondrial dysfunction, fibrosis and inflammation.

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Clinical symptoms of right ventricular failure in experimental chronic pressure load are associated with progressive diastolic dysfunction

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