Cardiomyocyte Metabolic Remodeling in Single Ventricle Heart Disease is Abrogated with Phosphodiesterase-5 Inhibitor Therapy

Abstract

Background: While operative and perioperative care continues to improve for single ventricle congenital heart disease (SV), long-term morbidities and mortality remain high. Importantly, phosphodiesterase-5 inhibitor therapies (PDE5i) are increasingly used, however, little is known regarding the direct myocardial effects of PDE5i therapy in the SV population.

Objectives: Our group has previously demonstrated that the failing SV myocardium is characterized by increased PDE5 activity and impaired mitochondrial bioenergetics. Here we sought to determine whether serum circulating factors contribute to pathological metabolic remodeling in SV, and whether PDE5i therapy abrogates these changes.

Methods: Using an established in vitro model whereby primary cardiomyocytes are treated with patient sera +/- PDE5i, we assessed the impact of circulating factors on cardiomyocyte metabolism. Mass spectrometry-based lipidomics and metabolomics were performed to identify phospholipid and metabolite changes. Mitochondrial bioenergetics were assessed using the Seahorse Bioanalyzer and a stable isotope based mitochondrial enzyme activity assay. Relative mitochondrial copy number was quantified using RT-qPCR.

Results: Our data suggest that serum circulating factors contribute to fundamental changes in cardiomyocyte bioenergetics, including decreased mitochondrial cardiolipin together with decreases in several other phospholipid species, increased reactive oxygen species (ROS) generation, impaired mitochondrial function, and altered metabolite profiles. Treatment with PDE5i therapy was sufficient to abrogate a number of these metabolic changes, including a rescue of phosphatidylglycerol levels, a reduction in ROS, improved energy production, and normalization of several key metabolic intermediates.

Conclusions: Together, these data suggest PDE5i therapy has direct cardiomyocyte effects and contributes to beneficial cardiomyocyte metabolic remodeling in SV failure.

Note:
Funding Information: This work was supported by the Nair Family, the Rose Foundation, the Jack Cooper Millisor Chair in Pediatric Heart Disease, and the National Heart, Lung, and Blood Institute (NHLBI) 3R01HL156670 to S.D. Miyamoto, C.C. Sucharov, and B.L. Stauffer. A.M. Garcia was supported by NHLBI 3R01HL156670-S1 and by the Colorado Nutrition and Obesity Research Center (NORC) pilot and feasibility award (P30 DK048520). The Additional Ventures Foundation Tools and Technology award to A.M Garcia and S.D. Miyamoto enabled the purchase of the Agilent Seahorse XFe Bioanalyzer.

Declaration of Interests: C.C Sucharov: Equity in miRagen, Inc. All other authors have declared that no conflict of interest exists.

Ethics Approval Statement: The studies performed were conducted according to Declaration of Helsinki principles and subjects or guardians of subjects under the age of 18 years gave written informed consent prior to inclusion in the study. The study was approved by the University of Colorado Anschutz Medical Campus Institutional Review Board.

Keywords: congenital heart disease, single ventricle, metabolism, phosphodiesterase-5, mitochondria