Multi-omic and multispecies analysis of right ventricular dysfunction.

BACKGROUND: Right ventricular failure (RVF) is a leading cause of morbidity and mortality in multiple cardiovascular diseases, but there are no treatments for RVF as therapeutic targets are not clearly defined. Contemporary transcriptomic/proteomic evaluations of RVF are predominately conducted in small animal studies, and data from large animal models are sparse. Moreover, a comparison of the molecular mediators of RVF across species is lacking. METHODS: Transcriptomics and proteomics analyses defined the pathways associated with cardiac magnetic resonance imaging (MRI)-derived values of RV hypertrophy, dilation, and dysfunction in control and pulmonary artery banded (PAB) pigs. Publicly available data from rat monocrotaline-induced RVF and pulmonary arterial hypertension patients with preserved or impaired RV function were used to compare molecular responses across species. RESULTS: PAB pigs displayed significant right ventricle/ventricular (RV) hypertrophy, dilation, and dysfunction as quantified by cardiac magnetic resonance imaging. Transcriptomic and proteomic analyses identified pathways associated with RV dysfunction and remodeling in PAB pigs. Surprisingly, disruptions in fatty acid oxidation (FAO) and electron transport chain (ETC) proteins were different across the 3 species. FAO and ETC proteins and transcripts were mostly downregulated in rats but were predominately upregulated in PAB pigs, which more closely matched the human response. All species exhibited similar dysregulation of the dilated cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy pathways. CONCLUSIONS: The porcine metabolic molecular signature was more similar to human RVF than rodents. These data suggest there may be divergent molecular responses of RVF across species, and pigs may more accurately recapitulate metabolic aspects of human RVF.

Ketone bodies in right ventricular failure: A unique therapeutic opportunity.

Background: Ketone bodies are pleotropic metabolites that play important roles in multiple biological processes ranging from bioenergetics to inflammation regulation via suppression of the NLRP3 inflammasome, and epigenetic modifications. Ketone bodies are elevated in left ventricular failure (LVF) and multiple approaches that increase ketone concentrations exert advantageous cardiac effects in rodents and humans. However, the relationships between ketone bodies and right ventricular failure (RVF) are relatively unexplored. Methods: 51 PAH patients were dichotomized into preserved or impaired RV function based on a cardiac index of 2.2 L/min/m2. Impaired RV function patients were further segmented into intermediate or severe RV dysfunction based on a right atrial pressure of 8 mm Hg. Serum ketone bodies acetoacetate (AcAc) and beta-hydroxybutyrate (ßOHB) were quantified using ultra performance liquid chromatography and mass spectrometry. In rodent studies, male Sprague Dawley rats were assigned to three groups: control (saline injection), monocrotaline (MCT) standard chow diet (MCT-Standard), and MCT ketogenic diet (MCT-Keto). Immunoblots and confocal microscopy probed macrophage NLRP3 activation in RV extracts and sections. RV fibrosis was determined by Picrosirus Red. Echocardiography evaluated RV function. Pulmonary arteriole remodeling was assessed from histological specimens. Results: Human RVF patients lacked a compensatory ketosis as serum AcAc and ßOHB levels were not associated with hemodynamic, echocardiographic, or biochemical measures of RV dysfunction. In rodent studies, AcAc and ßOHB levels were also not elevated in MCT-mediated RVF, but the ketogenic diet significantly increased AcAc and ßOHB levels. MCT-Keto exhibited suppressed NLRP3 activation with a reduction in NLRP3, ASC (apoptosis-associated speck-like protein), pro-caspase-1, and interleukin-1 beta on immunoblots. Moreover, the number of ASC-positive macrophage in RV sections was reduced, RV fibrosis was blunted, and RV function was augmented in MCT-Keto rats. Conclusion: The ketogenic response is blunted in pulmonary arterial hypertension (PAH) patients with RVF. In the MCT rat model of PAH-mediated RVF, a dietary-induced ketosis improves RV function, suppresses NLRP3 inflammasome activation, and combats RV fibrosis. The summation of these data suggest ketogenic therapies may be particularly efficacious in RVF, and therefore future studies evaluating ketogenic interventions in human RVF are warranted.

Sex differences in right ventricular function between Groups 1 and 3 pulmonary hypertension.

Group 3 pulmonary hypertension (PH) patients have disproportionate right ventricular dysfunction (RVD) compared to pulmonary arterial hypertension. We evaluated how sex and PH etiology modulated RVD. Strain echocardiography showed no intrasex differences between PH types. Heightened RVD in Group 3 PH may be due to a greater male proportion.

Effect of Combination of Balloon Pulmonary Angioplasty and Medical Therapy on Reverse Right Ventricular Remodeling and Hemodynamics in Chronic Thromboembolic Pulmonary Hypertension.

INTRODUCTION: Chronic thromboembolic pulmonary hypertension (CTEPH) is a progressive and debilitating disorder that results from incomplete resolution of vascular obstructions resulting in pulmonary hypertension. Surgical pulmonary thromboendarterectomy (PTE) is the treatment of choice for CTEPH. Unfortunately, many CTEPH patients are ineligible for PTE or do not have access to an expert surgical center. Medical therapy imparts important symptomatic and exercise benefits for CTEPH patients, but it does not extend survival. Balloon pulmonary angioplasty (BPA) is an emerging transcatheter approach that is both safe and efficacious. However, the potential synergy between upfront BPA and medical therapy treatment approaches in patients with inoperable CTEPH is unknown. Here, we evaluated how the combination of BPA and medical therapy compared to medical therapy alone in a newly established BPA program. METHODS: Twenty-one patients with inoperable or residual CTEPH were evaluated in this single-center observational study. Ten patients underwent upfront BPA and medical therapy while 11 patients were treated with medical therapy alone. Hemodynamic and echocardiographic assessments were performed at baseline and at least 1 month after completion of therapy. Continuous variables were compared using t-test or Mann-Whitney U-test. Categorical variables were analyzed with Chi squared and Fisher's exact test where appropriate. RESULTS: Combination therapy significantly reduced mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR), but medical therapy only significantly lowered PVR. Comprehensive echocardiographic analysis revealed a more robust reverse right ventricular (RV) remodeling effect and augmentation of RV function with combination therapy. At the end of study, the combination therapy group had lower mPAP and PVR and better RV function. Importantly, there were no significant adverse effects in patients treated with BPA. CONCLUSION: Combination therapy significantly improves hemodynamics and RV function in inoperable CTEPH while carrying an acceptable risk profile, even in a newly developed program. Further studies comparing upfront combination therapy to medical therapy with larger, long-term, and randomized approaches should be considered.

Ketone Bodies in Right Ventricular Failure: A Unique Therapeutic Opportunity.

Ketone bodies are pleotropic metabolites that play important roles in multiple biological processes ranging from bioenergetics to inflammation regulation via suppression of the NLRP3 inflammasome, and epigenetic modifications. Ketone bodies are elevated in left ventricular failure (LVF) and multiple approaches that increase ketone concentrations exert advantageous cardiac effects in rodents and humans. However, the relationships between ketone bodies and right ventricular failure (RVF) are relatively unexplored. Moreover, the cardioprotective properties of ketones in preclinical RVF are unknown. Here, we show a compensatory ketosis is absent in pulmonary arterial hypertension (PAH) patients with RVF. In the monocrotaline (MCT) rat model of PAH-mediated RVF, a dietary-induced ketosis improves RV function, suppresses NLRP3 inflammasome activation, and combats RV fibrosis. The summation of these data suggest ketogenic therapies may be particularly efficacious in RVF, and therefore future studies evaluating ketogenic interventions in human RVF are warranted.

Intermittent Fasting Activates AMP-Kinase to Restructure Right Ventricular Lipid Metabolism and Microtubules.

Intermittent fasting (IF) extends life span via pleotropic mechanisms, but one important molecular mediator is adenosine monophosphate-activated protein kinase (AMPK). AMPK enhances lipid metabolism and modulates microtubule dynamics. Dysregulation of these molecular pathways causes right ventricular (RV) failure in patients with pulmonary arterial hypertension. In rodent pulmonary arterial hypertension, IF activates RV AMPK, which restores mitochondrial and peroxisomal morphology and restructures mitochondrial and peroxisomal lipid metabolism protein regulation. In addition, IF increases electron transport chain protein abundance and activity in the right ventricle. Echocardiographic and hemodynamic measures of RV function are positively associated with fatty acid oxidation and electron transport chain protein levels. IF also combats heightened microtubule density, which normalizes transverse tubule structure.

A Multi-omic and Multi-Species Analysis of Right Ventricular Failure.

Right ventricular failure (RVF) is a leading cause of morbidity and mortality in multiple cardiovascular diseases, but there are no approved treatments for RVF as therapeutic targets are not clearly defined. Contemporary transcriptomic/proteomic evaluations of RVF are predominately conducted in small animal studies, and data from large animal models are sparse. Moreover, a comparison of the molecular mediators of RVF across species is lacking. Here, we used transcriptomics and proteomics analyses to define the molecular pathways associated with cardiac MRI-derived values of RV hypertrophy, dilation, and dysfunction in pulmonary artery banded (PAB) piglets. Publicly available data from rat monocrotaline-induced RVF and pulmonary arterial hypertension patients with preserved or impaired RV function were used to compare the three species. Transcriptomic and proteomic analyses identified multiple pathways that were associated with RV dysfunction and remodeling in PAB pigs. Surprisingly, disruptions in fatty acid oxidation (FAO) and electron transport chain (ETC) proteins were different across the three species. FAO and ETC proteins and transcripts were mostly downregulated in rats, but were predominately upregulated in PAB pigs, which more closely matched the human data. Thus, the pig PAB metabolic molecular signature was more similar to human RVF than rodents. These data suggest there may be divergent molecular responses of RVF across species, and that pigs more accurately recapitulate the metabolic aspects of human RVF.

Junctophilin-2 Regulates Mitochondrial Metabolism.

Right ventricular dysfunction (RVD) is a risk factor for mortality in multiple cardiovascular diseases, but approaches to combat RVD are lacking. Therapies used for left heart failure are largely ineffective in RVD, and thus the identification of molecules that augment RV function could improve outcomes in a wide-array of cardiac limitations. Junctophilin-2 (JPH2) is an essential protein that plays important roles in cardiomyocytes, including calcium handling/maintenance of t-tubule structure and gene transcription. Additionally, JPH2 may regulate mitochondrial function as Jph2 knockout mice exhibit cardiomyocyte mitochondrial swelling and cristae derangements. Moreover, JPH2 knockdown in embryonic stem cell-derived cardiomyocytes induces downregulation of the mitochondrial protein mitofusin-2 (MFN2), which disrupts mitochondrial cristae structure and transmembrane potential. Impaired mitochondrial metabolism drives RVD, and here we evaluated the mitochondrial role of JPH2. We showed JPH2 directly interacts with MFN2, ablation of JPH2 suppresses mitochondrial biogenesis, oxidative capacity, and impairs lipid handling in iPSC-CM. Gene therapy with AAV9-JPH2 corrects RV mitochondrial morphological defects, mitochondrial fatty acid metabolism enzyme regulation, and restores the RV lipidomic signature in the monocrotaline rat model of RVD. Finally, AAV-JPH2 improves RV function without altering PAH severity, showing JPH2 provides an inotropic effect to the dysfunction RV.

Ferroptosis Promotes Pulmonary Hypertension.

Background: Mitochondrial dysfunction, characterized by impaired lipid metabolism and heightened reactive oxygen species (ROS) generation, results in lipid peroxidation-induced ferroptosis. Ferroptosis is an inflammatory mode of cell death as it both promotes complement activation and recruits macrophages. In pulmonary arterial hypertension (PAH), pulmonary arterial endothelial cells exhibit disrupted lipid metabolism and increased ROS production, and there is ectopic complement deposition and inflammatory macrophage accrual in the surrounding vasculature. However, the integrative effects of ferroptosis on metabolism, cellular landscape changes in the lung, complement induction, and pulmonary vascular remodeling are unknown. Methods: Multi-omics analyses in rodents and a genetic association study in humans evaluated the role of ferroptosis in PAH. Results: Ferrostatin-1, a small-molecule ferroptosis inhibitor, mitigated PAH severity and improved right ventricular function in monocrotaline rats. RNA-seq and proteomics analyses demonstrated ferroptosis was induced with increasingly severe PAH. Metabolomics and proteomics data showed ferroptosis inhibition restructured lung metabolism and altered phosphatidylcholine and phosphatidylethanolamine levels. RNA-seq, proteomics, and confocal microscopy revealed complement activation and pro-inflammatory cytokines/chemokines were suppressed by ferrostatin-1. Additionally, ferrostatin-1 combatted changes in endothelial, smooth muscle, and interstitial macrophage abundances and gene activation patterns in the lungs as revealed by deconvolution RNA-seq. Finally, the presence of six single-nucleotide polymorphisms in ferroptosis genes were independently associated with pulmonary hypertension severity in the Vanderbilt BioVU repository. Conclusions: Rodent and human data nominate ferroptosis as a PAH regulating pathway via its ability to modulate lung lipid metabolism, repress pathogenic complement activation, dampen interstitial macrophage infiltration, and restore the lung cellular environment.

Pulmonary Arterial Hypertension Patients Have a Proinflammatory Gut Microbiome and Altered Circulating Microbial Metabolites.

Rationale: Inflammation drives pulmonary arterial hypertension (PAH). Gut dysbiosis causes immune dysregulation and systemic inflammation by altering circulating microbial metabolites; however, little is known about gut dysbiosis and microbial metabolites in PAH. Objectives: To characterize the gut microbiome and microbial metabolites in patients with PAH. Methods: We performed 16S ribosomal RNA gene and shotgun metagenomics sequencing on stool from patients with PAH, family control subjects, and healthy control subjects. We measured markers of inflammation, gut permeability, and microbial metabolites in plasma from patients with PAH, family control subjects, and healthy control subjects. Measurements and Main Results: The gut microbiome was less diverse in patients with PAH. Shannon diversity index correlated with measures of pulmonary vascular disease but not with right ventricular function. Patients with PAH had a distinct gut microbial signature at the phylogenetic level, with fewer copies of gut microbial genes that produce antiinflammatory short-chain fatty acids (SCFAs) and secondary bile acids and lower relative abundances of species encoding these genes. Consistent with the gut microbial changes, patients with PAH had relatively lower plasma concentrations of SCFAs and secondary bile acids. Patients with PAH also had enrichment of species with the microbial genes that encoded the proinflammatory microbial metabolite trimethylamine. The changes in the gut microbiome and circulating microbial metabolites between patients with PAH and family control subjects were not as substantial as the differences between patients with PAH and healthy control subjects. Conclusions: Patients with PAH have proinflammatory gut dysbiosis, in which lower circulating SCFAs and secondary bile acids may facilitate pulmonary vascular disease. These findings support investigating modulation of the gut microbiome as a potential treatment for PAH.

Cardiovascular Magnetic Resonance Imaging Phenotypes and Long-term Outcomes in Patients With Suspected Cardiac Sarcoidosis.

Importance: In patients with sarcoidosis with suspected cardiac involvement, late gadolinium enhancement (LGE) on cardiovascular magnetic resonance imaging (CMR) identifies those with an increased risk of adverse outcomes. However, these outcomes are experienced by only a minority of patients with LGE, and identifying this subgroup may improve treatment and outcomes in these patients. Objective: To assess whether CMR phenotypes based on left ventricular ejection fraction (LVEF) and LGE in patients with suspected cardiac sarcoidosis (CS) are associated with adverse outcomes during follow-up. Design, Setting, and Participants: This cohort study included consecutive patients with histologically proven sarcoidosis who underwent CMR for the evaluation of suspected CS from 2004 to 2020 with a median follow-up of 4.3 years at an academic medical center in Minnesota. Demographic data, medical history, comorbidities, medications, and outcome data were collected blinded to CMR data. Exposures: CMR phenotypes were identified based on LVEF and LGE presence and features. LGE was classified as pathology-frequent or pathology-rare based on the frequency of cardiac damage features on gross pathology assessment of the hearts of patients with CS who had sudden cardiac death or cardiac transplant. Main Outcomes and Measures: Composite of ventricular arrhythmic events and composite of heart failure events. Results: Among 504 patients (mean [SD] age, 54.1 [12.5] years; 242 [48.0%] female and 262 [52.0%] male; 2 [0.4%] American Indian or Alaska Native, 6 [1.2%] Asian, 90 [17.9%] Black or African American, 399 [79.2%] White, 5 [1.0%] of 2 or more races (including the above-mentioned categories and Native Hawaiian or Other Pacific Islander), and 2 [0.4%] of unknown race; 4 [0.8%] Hispanic or Latino, 498 [98.8%] not Hispanic or Latino, and 2 [0.4%] of unknown ethnicity), 4 distinct CMR phenotypes were identified: normal LVEF and no LGE (n = 290; 57.5%), abnormal LVEF and no LGE (n = 53; 10.5%), pathology-frequent LGE (n = 103; 20.4%), and pathology-rare LGE (n = 58; 11.5%). The phenotype with pathology-frequent LGE was associated with a high risk of arrhythmic events (hazard ratio [HR], 12.12; 95% CI, 3.62-40.57; P < .001) independent of LVEF and extent of left ventricular late gadolinium enhancement (LVLGE). It was also associated with a high risk of heart failure events (HR, 2.49; 95% CI, 1.19-5.22; P = .02) independent of age, pulmonary hypertension, LVEF, right ventricular ejection fraction, and LVLGE extent. Risk of arrhythmic events was greater with an increasing number of pathology-frequent LGE features. The absence of the pathology-frequent LGE phenotype was associated with a low risk of arrhythmic events, even in the presence of LGE or abnormal LVEF. Conclusions and Relevance: This cohort study found that a CMR phenotype involving pathology-frequent LGE features was associated with a high risk of arrhythmic and heart failure events in patients with sarcoidosis. The findings indicate that CMR phenotypes could be used to optimize clinical decision-making for treatment options, such as implantable cardioverter-defibrillators.

Glyoxylase-1 combats dicarbonyl stress and right ventricular dysfunction in rodent pulmonary arterial hypertension.

Background: Heightened glycolytic flux is associated with right ventricular (RV) dysfunction in pulmonary arterial hypertension (PAH). Methylglyoxal, a glycolysis byproduct, is a highly reactive dicarbonyl that has toxic effects via non-enzymatic post-translational modifications (protein glycation). Methylglyoxal is degraded by the glyoxylase system, which includes the rate-limiting enzyme glyoxylase-1 (GLO1), to combat dicarbonyl stress. However, the potential consequences of excess protein glycation on RV function are unknown. Methods: Bioinformatics analysis of previously identified glycated proteins predicted how protein glycation regulated cardiac biology. Methylglyoxal treatment of H9c2 cardiomyocytes evaluated the consequences of excess protein glycation on mitochondrial respiration. The effects of adeno-associated virus serotype 9-mediated (AAV9) GLO1 expression on RV function in monocrotaline rats were quantified with echocardiography and hemodynamic studies. Immunoblots and immunofluorescence were implemented to probe the effects of AAV-Glo1 on total protein glycation and fatty acid oxidation (FAO) and fatty acid binding protein levels. Results: In silico analyses highlighted multiple mitochondrial metabolic pathways may be affected by protein glycation. Exogenous methylglyoxal minimally altered mitochondrial respiration when cells metabolized glucose, however methylglyoxal depressed FAO. AAV9-Glo1 increased RV cardiomyocyte GLO1 expression, reduced total protein glycation, partially restored mitochondrial density, and decreased lipid accumulation. In addition, AAV9-Glo1 increased RV levels of FABP4, a fatty acid binding protein, and hydroxyacyl-CoA dehydrogenase trifunctional multienzyme complex subunits alpha and beta (HADHA and HADHB), the two subunits of the mitochondrial trifunctional protein for FAO. Finally, AAV9-Glo1 blunted RV fibrosis and improved RV systolic and diastolic function. Conclusion: Excess protein glycation promotes RV dysfunction in preclinical PAH, potentially through suppression of FAO.

Ingenuity pathway analysis of the human cardiac cell Atlas identifies differences between right and left ventricular cardiomyocytes.

Pharmaceuticals for left ventricular (LV) dysfunction do not have similar success in right ventricular (RV) failure, which may reflect biological differences between the ventricles. In this study, we performed Ingenuity Pathway Analysis of the Human Cell Atlas to understand how the transcriptomic signatures of the RV and LV differ.

Prognostic impact of identifying etiology of prosthetic valve dysfunction with CT.

BACKGROUND: In patients with prosthetic heart valves (PHV), there are distinct treatment implications based on prosthetic valve dysfunction (PVD) etiology. We investigated whether evaluation for PVD etiology on computed tomography (CT) has prognostic value for adverse clinical outcomes. METHODS: Consecutive patients with suspected PVD that had a clinically indicated contrast chest CT and echocardiogram done within 1 year of each other were identified retrospectively from the Prosthetic Heart Valve CT Registry at the University of Minnesota. CTs and echocardiograms were assessed for potential PVD etiologies of pannus, structural valve degeneration (SVD) and thrombus, as per standard guidelines. Kaplan-Meier and Cox regression analyses were performed to assess association with a composite outcome of reoperation and all-cause mortality. RESULTS: 132 patients (51.5% male, mean age 62.1 â€‹± â€‹19.3 years) with suspected PVD were included. There were 97 tissue valves, 31 mechanical valves and 4 transcatheter valves. The location of the valve was as follows: 72 aortic, 45 mitral, 8 tricuspid, and 7 pulmonic. A PVD etiology was diagnosed on CT in 80 (60.6%) patients, and on echocardiography in 45 (34.1%) patients, largely driven by a diagnosis of SVD on both modalities. Significant univariate predictors of the composite outcome included CT diagnosis of SVD (P â€‹< â€‹0.001), echocardiography diagnosis of SVD (P â€‹< â€‹0.001), degree of prosthetic stenosis (P â€‹< â€‹0.001) and degree of prosthetic regurgitation (P â€‹< â€‹0.001). On multivariable analyses adjusted for age, sex, left ventricular function, degree of prosthetic stenosis and degree of prosthetic regurgitation, CT diagnosis of SVD was significantly associated with the composite outcome (HR: 1.79, 1.09-2.95) whereas echocardiography diagnosis of SVD was not (HR: 1.56, 0.98-2.46). CONCLUSION: In patients with suspected PVD, CT assessment of SVD had prognostic significance for hard outcomes. CT should be considered in the diagnostic evaluation of patients with suspected PVD.

Right Ventricular Abnormalities on Cardiovascular Magnetic Resonance Imaging in Patients With Sarcoidosis.

OBJECTIVES: This study aimed to determine the prevalence on cardiac magnetic resonance (CMR) of right ventricular (RV) systolic dysfunction and RV late gadolinium enhancement (LGE), their determinants, and their influences on long-term adverse outcomes in patients with sarcoidosis. BACKGROUND: In patients with sarcoidosis, RV abnormalities have been described on many imaging modalities. On CMR, RV abnormalities include RV systolic dysfunction quantified as an abnormal right ventricular ejection fraction (RVEF), and RV LGE. METHODS: Consecutive patients with biopsy-proven sarcoidosis who underwent CMR for suspected cardiac involvement were studied. They were followed for 2 endpoints: all-cause death, and a composite arrhythmic endpoint of sudden cardiac death or significant ventricular arrhythmia. RESULTS: Among 290 patients, RV systolic dysfunction (RVEF <40% in men and <45% in women) and RV LGE were present in 35 (12.1%) and 16 (5.5%), respectively. The median follow-up time was 3.2 years (interquartile range [IQR]: 1.6 to 5.7 years) for all-cause death and 3.0 years (IQR: 1.4 to 5.5 years) for the arrhythmic endpoint. On Cox proportional hazards regression multivariable analyses, only RVEF was independently associated with all-cause death (hazard ratio [HR]: 1.05 for every 1% decrease; 95% confidence interval [CI]: 1.01 to 1.09; p = 0.022) after adjustment for left ventricular EF, left ventricular LGE extent, and the presence of RV LGE. RVEF was not associated with the arrhythmic endpoint (HR: 1.01; 95% CI: 0.96 to 1.06; p = 0.67). Conversely, RV LGE was not associated with all-cause death (HR: 2.78; 95% CI: 0.36 to 21.66; p = 0.33), while it was independently associated with the arrhythmic endpoint (HR: 5.43; 95% CI: 1.25 to 23.47; p = 0.024). CONCLUSIONS: In this study of patients with sarcoidosis, RV systolic dysfunction and RV LGE had distinct prognostic associations; RV systolic dysfunction but not RV LGE was independently associated with all-cause death, whereas RV LGE but not RV systolic dysfunction was independently associated with sudden cardiac death or significant ventricular arrhythmia. These findings may indicate distinct implications for the management of RV abnormalities in sarcoidosis.