Phosphodiesterase-5 Is Elevated in Failing Single Ventricle Myocardium and Affects Cardiomyocyte Remodeling In Vitro

Abstract

Background: Single ventricle congenital heart disease (SV) is fatal without intervention and eventual heart failure (HF) is a major cause of morbidity and mortality. While there are no proven medical therapies for the treatment or prevention of HF in the SV population, phosphodiesterase-5 inhibitors (PDE5i), such as sildenafil, are increasingly utilized. While the pulmonary vasculature is the primary target of PDE5i therapy in patients with SV, the effects of PDE5i on the SV myocardium remain largely unknown. We sought to determine PDE5 expression and activity in the single right ventricle (RV) of SV patients relative to non-failing (NF) controls, and to determine if PDE5 impacts cardiomyocyte remodeling using a novel serum based in vitro model. Methods and Results: PDE5 expression (n=9 NF, n=7 SV), activity (n=8 NF, n=9 SV) and localization (n=3 SV) were determined in explanted human RV myocardium. PDE5 is expressed in SV cardiomyocytes and PDE5 protein expression and activity are increased in SV RV compared to NF RV. Isolated neonatal rat ventricular myocytes (NRVMs) were treated for 72 hours with NF or SV patient serum ± sildenafil. RT-qPCR (n=5 NF, n=12 SV) and RNAseq (n=3 NF, n=3 SV) were performed on serum-treated NRVMs and demonstrated that treatment with SV sera results in pathological gene expression changes which are attenuated with PDE5i. Conclusions: PDE5 is increased in failing SV myocardium and pathologic gene expression changes in SV serum-treated NRVMs are abrogated by PDE5i. These results suggest that PDE5 represents an intriguing myocardial therapeutic target in this population.

Mitochondrial Respiration Defects in Single-Ventricle Congenital Heart Disease

“…Interestingly, an increase in mitochondrial reserve and maximal capacity has also been reported in the platelets of adults with pulmonary hypertension ( 18 ), a common comorbidity in CHD patients. We noted a previous study that showed that serum from SV-CHD patients ( 5 ) can cause pathological remodeling with the reactivation of fetal gene programs in neonatal rat cardiomyocytes. The expression of HF markers, such as BNP ( 19 ) and atrial natriuretic factor ( 20 ) were observed, with transcriptome profiling showing metabolic process as one of the top enriched pathways.…”

“…Consistent with this, transcriptome profiling of the HLHS mouse heart tissue yielded metabolic pathways among the top pathways impacted ( 4 ). Supporting clinical evidence has come from a recent study showing that serum isolated from SV-CHD patients can induce pathological changes in neonatal rat cardiomyocytes ( 5 ). Transcriptome profiling of the treated cardiomyocytes showed that 23% of the genes impacted were related to metabolic processes ( 5 ).…”

Primary Human Cardiomyocytes and Cardiofibroblasts Treated with Sera from Myocarditis Patients Exhibit an Increased Iron Demand and Complex Changes in the Gene Expression

“…Treatment with sera from patients with various cardiac diseases has been shown to induce changes in many different processes in cultured cells. Recently, Garcia et al showed that the treatment with single ventricle heart disease sera results in detrimental gene expression changes in cultured neonatal rat ventricular myocytes [ 29 ]. Furthermore, treatment with serum from heart failure (HF) patients or acute myocardial infraction (MI) has been shown to induce apoptosis and enhanced sprouting angiogenesis of cultured endothelial cells [ 30 , 31 ].…”

Physiology of the Right Ventricle Across the Lifespan

“…There is an interesting contrast in therapies such as phosphodiesterase inhibitors (PDEi) that have been found to be effective and safe in pediatric patients with heart failure but not as safe in adults (reviewed; Miyamoto et al, 2018 ). Moreover, PDE5i may be beneficial in improving RV function but it difficult to determine if this improvement is due to direct cardiomyocyte effects or simply improvement in pulmonary vascular function ( Nagendran et al, 2007 ; Garcia et al, 2018 ). It is not clear if PDEi are beneficial in RV function in adults.…”