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This manuscript on real-world evidence (RWE) in pulmonary hypertension (PH) incorporates the broad experience of members of the Pulmonary Vascular Research Institute's Innovative Drug Development Initiative Real-World Evidence Working Group. We aim to strengthen the research community's understanding of RWE in PH to facilitate clinical research advances and ultimately improve patient care. Herein, we review real-world data (RWD) sources, discuss challenges and opportunities when using RWD sources to study PH populations, and identify resources needed to support the generation of meaningful RWE for the global PH community., Competing Interests: Boucly reports consulting fees from AOP Orphan; payment, honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from AOP Orphan, MSD, and Janssen; and support for attending meetings/travel from MSD and Janssen. Moles reports grants or contracts from Acceleron Pharma, Janssen, and CVS Caremark; and leadership or fiduciary role in other board, society, committee, or advocacy group, paid or unpaid, for Gossamer Bio. Elwing reports grants or contracts from United Therapeutics Corporation, Gossamer Bio, Bayer, Acceleron/Merck, Altavant, Aerovate, Tenax, Pharmosa, Actelion/Janssen, Arena, Lung, Liquidia, and Phase Bio; consulting fees for United Therapeutics Corporation; support for attending meetings and/or travel for United Therapeutics, Altavant, Aerovate, Bayer, Gossamer Bio, Liquida, Acceleron/Merck, Janssen/Actelion, and Insmed; and other financial or nonfinancial interests from Bayer as a grant reviewer. Jose reports grants or contracts from Team Phenomenal Hope Charity, Francis Family Foundation, United Therapeutics, and Janssen/Johnson & Johnson. Alves Jr. reports payment or honoraria from Bayer and Janssen; and support for attending meetings and/or travel from Janssen. Minty reports consulting fees from Janssen Pharmaceuticals and Orpyx Medical Technologies; and stock or stock options from Orpyx Medical Technologies. Weatherald reports grants or contracts from Janssen, Bayer, Merck, Canadian Institutes for Health Research, and the Heart & Stroke Foundation of Canada; consulting fees from Janssen and Merck; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Janssen and Merck; payment for expert testimony from Sprigings Intellectual Property Law; support for attending meetings and/or travel from Janssen; participation on a data safety monitoring board or advisory board from Janssen, Acceleron, and Université Laval; and leadership or fiduciary role in other board, society, committee or advocacy group, paid or unpaid, from the Pulmonary Hypertension Association of Canada. Mathai reports grants or contracts from NIH/NHLBI (HL125175) and DOD (W81XWH‐20‐1‐0768); consulting fees from Actelion/Janssen, Aerovate, Merck, United Therapeutics Corporation, and Theravance; and participation on a data safety monitoring board or advisory board from Bayer. Sahay reports grants or contracts from United Therapeutics Corporation, Janssen, Bayer, Merck, Liquidia, and Gossamer; consulting fees from Merck, Liquidia, and Gossamer; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from United Therapeutics Corporation (received by hospital rather than self); patents planned, issued, or pending with Janssen; and participation on a data safety monitoring board or advisory board with GSK, Bayer, United Therapeutics, and Janssen. Pulido reports grants or contracts from Janssen, MSD, and United Therapeutics; consulting fees from Janssen, Bayer, Gossamer, and MSD; and payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Bayer, Janssen, and Pfizer. Badagliacca reports grants or contracts from United Therapeutics Corporation, Ferrer, and Janssen; consulting fees from MSD, United Therapeutics Corporation, Ferrer, Janssen, and AOP; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from MSD, United Therapeutics Corporation, Ferrer, Janssen, and AOP; and support for attending meetings and/or travel from MSD, United Therapeutics Corporation, Ferrer, Janssen, and AOP. Cirulis reports grants or contracts from Entelligence (now ATS); and leadership or fiduciary role in other board, society, committee or advocacy group, paid or unpaid, with ATS Web Committee Co‐Director and ATS Program Committee. Gerges reports grants or contracts from AOP Health; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from AOP Health, Actelion/Janssen, and Ferrer; and support for attending meetings and/or travel from AOP Health, Actelion/Janssen, Ferrer, Daiichi Sankyo, and MSD. Gillmeyer reports grants or contracts from Parker B. Francis Fellowship Award, Doris Duke Charitable Foundation Award, and National Center for Advancing Translational Sciences, National Institutes of Health (BU‐CTSI Grant Number 1UL1TR001430); and leadership or fiduciary role in other board, society, committee or advocacy group, paid or unpaid, for the American Thoracic Society Program Committee (unpaid). Hobohm reports consulting fees for Janssen, Boston Consulting, and MSD. Lau reports grants or contracts from Janssen and GSK; consulting fees for Janssen; and payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Janssen. Morland reports grants or contracts from United Therapeutics Corporation; leadership or fiduciary role in other board, society, committee or advocacy group, paid or unpaid, from the PVRI Innovative Drug Development Initiative (unpaid); and stock or stock options from United Therapeutics Corporation. Nikkho reports grants or contracts from Bayer AG; and leadership or fiduciary role in other board, society, committee or advocacy group, paid or unpaid, from the PVRI Innovative Drug Development Initiative (unpaid). The remaining authors declare no conflict of interest., (© 2023 The Authors. Pulmonary Circulation published by John Wiley & Sons Ltd on behalf of Pulmonary Vascular Research Institute.)

Background Pulmonary vascular distensibility associates with right ventricular function and clinical outcomes in patients with unexplained dyspnea and pulmonary hypertension. Alpha distensibility coefficient is determined from a nonlinear fit to multipoint pressure-flow plots. Study aims were to (1) create and test a user-friendly tool to standardize analysis of exercise hemodynamics including distensibility, and (2) investigate changes in distensibility following treatment in patients with pulmonary arterial hypertension. Methods and Results Participants with an exercise right heart catherization were retrospectively identified from the University of Arizona Pulmonary Hypertension (UA PH) registry and split into a pulmonary arterial hypertension group, a comparator group, and a control group. Right ventricular function was quantified using the coupling ratio and diastolic stiffness. Prototypes of the invasive cardiopulmonary exercise testing (iCPET) calculator were developed using Matlab, Python, and RShiny to analyze exercise hemodynamics and alpha distensibility coefficient, α (%/mm Hg) from multipoint pressure flow plots. Interclass correlation coefficients were calculated for interplatform and interobserver variability in alpha. No significant bias in the intraplatform (Matlab versus RShiny; intraclass correlation coefficient: 0.996) or interobserver (intraclass correlation coefficient: 0.982) comparison of alpha values. Afterload significantly decreased ( P <0.05) with no change in alpha distensibility in the pulmonary arterial hypertension group at follow-up. The comparator group had no change in pressure, resistance or alpha distensibility. There were no significant changes in RV diastolic stiffness at follow-up. Conclusions The interactive user interface in the iCPET calculator allows exploration of alpha distensibility using standardized methods. No significant change in alpha distensibility at follow-up suggests that alpha may be less modifiable in patients with long-standing pulmonary arterial hypertension.

Background: Normative changes in right ventricular (RV) structure and function have not been characterized in the context of treatment-associated functional recovery (RV functional recovery [RVFnRec]). The aim of this study is to assess the clinical relevance of a proposed RVFnRec definition., Methods: We evaluated 63 incident patients with pulmonary arterial hypertension by right heart catheterization and cardiac magnetic resonance imaging at diagnosis and cardiac magnetic resonance imaging and invasive cardiopulmonary exercise testing following treatment (≈11 months). Sex, age, ethnicity matched healthy control subjects (n=62) with 1-time cardiac magnetic resonance imaging and noninvasive cardiopulmonary exercise testing were recruited from the PVDOMICS (Redefining Pulmonary Hypertension through Pulmonary Vascular Disease Phenomics) project. We examined therapeutic cardiac magnetic resonance imaging changes relative to the evidence-based peak oxygen consumption (VO 2peak )>15 mL/(kg·min) to define RVFnRec by receiver operating curve analysis. Afterload was measured as mean pulmonary artery pressure, resistance, compliance, and elastance., Results: A drop in RV end-diastolic volume of -15 mL best defined RVFnRec (area under the curve, 0.87; P =0.0001) and neared upper 95% CI RV end-diastolic volume of controls. This cutoff was met by 22 out of 63 (35%) patients which was reinforced by freedom from clinical worsening, RVFnRec 1 out of 21 (5%) versus no RVFnRec 17 out of 42, 40% (log-rank P =0.006). A therapy-associated increase of 0.8 mL/mm Hg in compliance had the best predictive value of RVFnRec (area under the curve, 0.76; [95% CI, 0.64-0.88]; P =0.001). RVFnRec patients had greater increases in stroke volume, and cardiac output at exercise., Conclusions: RVFnRec defined by RV end-diastolic volume therapeutic decrease of -15 mL predicts exercise capacity, freedom from clinical worsening, and nears normalization. A therapeutic improvement of compliance is superior to other measures of afterload in predicting RVFnRec. RVFnRec is also associated with increased RV output reserve at exercise., Competing Interests: Disclosures Dr Rischard has consulting relationships with Bayer and receives research support from Ismed, United Therapeutics, Bayer, Acceleron, Merck, and Janssen. Dr Naeije reports relationships including consultancies, speakers fees, and membership of advisory boards with AOP Orphan Pharmaceuticals, Johnson & Johnson, Lung Biotechnology Corporation, and United Therapeutics. Dr Garcia is Chief Executive Officer and founder of Aqualung Therapeutics Corporation. Dr Frantz has consulting, steering committee, and advisory board relationships with Altavant Sciences, Bayer, Gossamer Bio, Janssen, Shouti, France Foundation, IQVIA, Tenax, UpToDate, and United Therapeutics. Dr Hassoun has served as consultant for Merck. Dr Hemnes has consulting relationships with Janssen, Merck, Gossamer, Bio, United Therapeutics, Bayer, Tenax. She owns stock in Tenax therapeutics and she has received research support from National Heart, Lung, and Blood Institute and Cardiovascular Medical Research and Education Fund. Dr Hill is the chair for an Aerovate steering committee. He is a consultant for Bellerophon and Liquidia and Merck. Dr Horn has consulting relationships with Biotronik and AADI biosciences. She serves on the DSMB for SoniVie and V-waves Ltd. She receives research support from Merck and Cereno. Dr Leopold Abbott has served as a consultant for Aria. She has research support from Astellas Pharma and United Therapeutics. Dr Rosenzweig has received consulting fees from Acceleron for a scientific advisory board meeting; and her institution receives grant support from Bayer, United Therapeutics, Janssen, and SonVie. Dr Tang served as consultant for Sequana Medical, Cardiol Therapeutics, Genomics plc, Zehna Therapeutics, Renovacor, WhiteSwell, Kiniksa, Boston Scientific, and CardiaTec Biosciences and has received honorarium from Springer Nature and American Board of Internal Medicine. The other authors report no conflicts.

Cardiomyopathy is a progressive disease of the myocardium leading to impaired contractility. Genotoxic cancer therapies are known to be potent drivers of cardiomyopathy, whereas causes of spontaneous disease remain unclear. To test the hypothesis that endogenous genotoxic stress contributes to cardiomyopathy, we deleted the DNA repair gene Ercc1 specifically in striated muscle using a floxed allele of Ercc1 and mice expressing Cre under control of the muscle-specific creatinine kinase (Ckmm) promoter or depleted systemically (Ercc1 -/D mice). Ckmm-Cre +/- ;Ercc1 -/fl mice expired suddenly of heart disease by 7 months of age. As young adults, the hearts of Ckmm-Cre +/- ;Ercc1 -/fl mice were structurally and functionally normal, but by 6-months-of-age, there was significant ventricular dilation, wall thinning, interstitial fibrosis, and systolic dysfunction indicative of dilated cardiomyopathy. Cardiac tissue from the tissue-specific or systemic model showed increased apoptosis and cardiac myocytes from Ckmm-Cre +/- ;Ercc1 -/fl mice were hypersensitive to genotoxins, resulting in apoptosis. p53 levels and target gene expression, including several antioxidants, were increased in cardiac tissue from Ckmm-Cre +/- ;Ercc1 -/fl and Ercc1 -/D mice. Despite this, cardiac tissue from older mutant mice showed evidence of increased oxidative stress. Genetic or pharmacologic inhibition of p53 attenuated apoptosis and improved disease markers. Similarly, overexpression of mitochondrial-targeted catalase improved disease markers. Together, these data support the conclusion that DNA damage produced endogenously can drive cardiac disease and does so mechanistically via chronic activation of p53 and increased oxidative stress, driving cardiac myocyte apoptosis, dilated cardiomyopathy, and sudden death., (© 2023 The Authors. Aging Cell published by Anatomical Society and John Wiley & Sons Ltd.)

Background: PVDOMICS (Pulmonary Vascular Disease Phenomics) is a precision medicine initiative to characterize pulmonary vascular disease (PVD) using deep phenotyping. PVDOMICS tests the hypothesis that integration of clinical metrics with omic measures will enhance understanding of PVD and facilitate an updated PVD classification., Objectives: The purpose of this study was to describe clinical characteristics and transplant-free survival in the PVDOMICS cohort., Methods: Subjects with World Symposium Pulmonary Hypertension (WSPH) group 1-5 PH, disease comparators with similar underlying diseases and mild or no PH and healthy control subjects enrolled in a cross-sectional study. PH groups, comparators were compared using standard statistical tests including log-rank tests for comparing time to transplant or death., Results: A total of 1,193 subjects were included. Multiple WSPH groups were identified in 38.9% of PH subjects. Nocturnal desaturation was more frequently observed in groups 1, 3, and 4 PH vs comparators. A total of 50.2% of group 1 PH subjects had ground glass opacities on chest computed tomography. Diffusing capacity for carbon monoxide was significantly lower in groups 1-3 PH than their respective comparators. Right atrial volume index was higher in WSPH groups 1-4 than comparators. A total of 110 participants had a mean pulmonary artery pressure of 21-24 mm Hg. Transplant-free survival was poorest in group 3 PH., Conclusions: PVDOMICS enrolled subjects across the spectrum of PVD, including mild and mixed etiology PH. Novel findings include low diffusing capacity for carbon monoxide and enlarged right atrial volume index as shared features of groups 1-3 and 1-4 PH, respectively; unexpected, frequent presence of ground glass opacities on computed tomography; and sleep alterations in group 1 PH, and poorest survival in group 3 PH. PVDOMICS will facilitate a new understanding of PVD and refine the current PVD classification. (Pulmonary Vascular Disease Phenomics Program PVDOMICS [PVDOMICS]; NCT02980887)., Competing Interests: Funding Support and Author Disclosures The study received grants U01 HL125218 (Principal Investigator: Dr Rosenzweig), U01 HL125205 (Principal Investigator: Dr Frantz), U01 HL125212 (Principal Investigator: Dr Hemnes), U01 HL125208 (Principal Investigator: Dr Rischard), U01 HL125175 (Principal Investigator: Dr Hassoun), U01 HL125215 (Principal Investigator: Dr Leopold), and U01 HL125177 (Principal Investigator: Dr Beck) and was supported by the Pulmonary Hypertension Association. Dr Hemnes has served as a consultant for Bayer, United Therapeutics, Janssen, GossamerBio, and Tenax Therapeutics; holds stock in Tenax Therapeutics; and has received grants from the National Institutes of Health, CMREF, and Imara. Dr Leopold is supported by the National Institutes of Health grant U01 125215 and the American Heart Association 19AIML34980000; receives salary support from the Massachusetts Medical Society; has received research funding (to her institution) from Astellas; has served as a consultant for Abbott Vascular and United Therapeutics; and has served as a site principal investigator for a study sponsored by Aria CV. Dr Abidov is supported by research grants from Astellas Pharma, Boehringer Ingelheim, and Kiniksa outside of the submitted work. Dr Rosenzweig has received consulting fees from Acceleron for a scientific advisory board meeting; and her institution receives grant support from Bayer, United Therapeutics, Janssen, and SonVie. Dr Borlaug has received research grants from National Institutes of Health/NHLBI, AstraZeneca, Medtronic, GlaxoSmithKline, Mesoblast, Novartis, and Tenax Therapeutics; and has received consulting fees from Actelion, Amgen, Aria, Axon Therapies, Boehringer Ingelheim, Edwards Lifesciences, Eli Lilly, Imbria, Janssen, Merck, Novo Nordisk, and VADovations. Dr Dubrock has received consulting fees from Janssen Pharmaceuticals; and has served on advisory boards for Janssen Pharmaceuticals and United Therapeutics. Dr Finet is a consultant to Wolters Kluwer Health, Clinical Drug Information Ad Honorem. Dr Frantz has consulting, steering committee, and advisory board relationships with Altavant Sciences, Bayer, Gossamer Bio, Janssen, Shouti, France Foundation, IQVIA, Tenax, UpToDate, and United Therapeutics. Dr Garcia is CEO and founder of Aqualing Therapeutics. Dr Hassoun has served as scientific advisor for Merck Sharp & Dohme, an activity unrelated to the current work. Dr Highland has grants/contracts with Acceleron Pharmaceuticals, Actelion Pharmaceuticals (Janssen), Bayer Healthcare, Boehringer Ingelheim, Eiger Pharmaceuticals, Eli Lilly, Gossamer Bio, United Therapeutics, and Viela Bio (Horizon); has served as a consultant and/or member of a steering or advisory committee with Acceleron Pharmaceuticals, Actelion Pharmaceuticals (Janssen), Boehringer Ingelheim, Forsee, Genentech, Gossamer Bio, and United Therapeutics; and has served on the Speakers Bureau for Actelion Pharmaceuticals (Janssen), Bayer Healthcare, Boehringer Ingelheim, and United Therapeutics. Dr Hill has received research grants for Acceleron, Aerovate. Altavant, Gossamer. Liquidia, Merck, and United Therapeutics; and has served on advisory boards for Acceleron, Aerovate, Altavant, Gossamer, and Liquidia. Dr Maron has relationships with Deerfield Corporation, Actelion Sciences, and Tenax Therapeutics; and has U.S. Patent #9,605,047, Patent pending PCT/US2019/059890, Patent application 2021/133937. Dr Mathai has served as a consultant for Acceleron, Actelion, Bayer, and United Therapeutics. Dr Mehra is supported by National Institutes of Health grants U01HL125177 and UH3HL140144 and the American Heart Association AHA 18SFRN34170013; has received royalties from Up to Date; has received compensation from the American Board of Internal Medicine; and has received an honorarium from the American Academy of Sleep Medicine. M.M. Park has served on the Speakers Bureau of Lantheus Medical Imaging (Definity contrast). Dr Rischard has consulting relationships with Acceleron and United Therapeutics; is on a Steering Committee for Acceleron; and receives research support from Ismed, United Therapeutics, Bayer, Acceleron, Janssen, and AADI. Dr Thomas has served as a consultant for GE, Abbott, egnite, EchoIQ, and Caption Health; as well as spouse employment for Caption Health. Dr Horn has served on the Data and Safety Monitoring Board of AADi Biosciences and SoniVie; has served on the Clinical Events Committee for V-wave; and has served as a consultant for Biotronik. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2022 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Prostacyclin analogs are among the most effective and widely used therapies for pulmonary arterial hypertension (PAH). However, it is unknown whether they also confer protection through right ventricle (RV) myocardio-specific mechanisms. Moreover, the use of prostacyclin analogs in severe models of PAH has not been adequately tested. To further identify underlying responses to prostacyclin, a prostacyclin analogue, treprostinil, was used in a preclinical rat Sugen-chronic hypoxia (SuCH) model of severe PAH that closely resembles the human disease. Male Sprague-Dawley rats were implanted with osmotic pumps containing vehicle or treprostinil, injected concurrently with a bolus of Sugen (SU5416) and exposed to 3-week hypoxia followed by 3-week normoxia. RV function was assessed using pressure-volume loops and hypertrophy by weight assessed. To identify altered mechanisms within the RV, tissue samples were used to perform a custom RNA array analysis, histological staining, and protein and transcript level confirmatory analyses. Treprostinil significantly reduced SuCH-associated RV hypertrophy and decreased the rise in RV systolic pressure, mean pulmonary arterial (mPAP), and right atrial (RAP) pressure. Prostacyclin treatment was associated with improvements in RV stroke work, maximum rate of ventricular pressure change (max dP/dt) and the contractile index, and almost a complete reversal of SuCH-associated increase in RV end-systolic elastance, suggesting the involvement of load-independent improvements in intrinsic RV systolic contractility by prostacyclin treatment. An analysis of the RV tissues showed no changes in cardiac mitochondrial respiration and ATP generation. However, custom RNA array analysis revealed amelioration of SuCH-associated increases in newly identified TBX20 as well as the fibrotic markers collagen1α1 and collagen 3α1 upon treprostinil treatment. Taken together, our data support decreased afterload and load-independent improvements in RV function following prostacyclin administration in severe PAH, and these changes appear to associate with improvements in RV fibrotic responses.

Background: Right ventricular (RV) dilation has been used to predict adverse outcomes in acute pulmonary conditions. It has been used to categorize the severity of novel coronavirus infection (COVID-19) infection. Our study aimed to use chest CT-angiogram (CTA) to assess if increased RV dilation, quantified as an increased RV:LV (left ventricle) ratio, is associated with adverse outcomes in the COVID-19 infection, and if it occurs out of proportion to lung parenchymal disease., Results: We reviewed clinical, laboratory, and chest CTA findings in COVID-19 patients (n = 100), and two control groups: normal subjects (n = 10) and subjects with organizing pneumonia (n = 10). On a chest CTA, we measured basal dimensions of the RV and LV in a focused 4-chamber view, and dimensions of pulmonary artery (PA) and aorta (AO) at the PA bifurcation level. Among the COVID-19 cohort, a higher RV:LV ratio was correlated with adverse outcomes, defined as ICU admission, intubation, or death. In patients with adverse outcomes, the RV:LV ratio was 1.06 ± 0.10, versus 0.95 ± 0.15 in patients without adverse outcomes. Among the adverse outcomes group, compared to the control subjects with organizing pneumonia, the lung parenchymal damage was lower (22.6 ± 9.0 vs. 32.7 ± 6.6), yet the RV:LV ratio was higher (1.06 ± 0.14 vs. 0.89 ± 0.07). In ROC analysis, RV:LV ratio had an AUC = 0.707 with an optimal cutoff of RV:LV ≥ 1.1 as a predictor of adverse outcomes. In a validation cohort (n = 25), an RV:LV ≥ 1.1 as a cutoff predicted adverse outcomes with an odds ratio of 76:1., Conclusions: In COVID-19 patients, RV:LV ratio ≥ 1.1 on CTA chest is correlated with adverse outcomes. RV dilation in COVID-19 is out of proportion to parenchymal lung damage, pointing toward a vascular and/or thrombotic injury in the lungs., (© 2022. The Author(s).)

Treatment with mineralocorticoid receptor (MR) antagonists beginning at the outset of disease, or early thereafter, prevents pulmonary vascular remodeling in preclinical models of pulmonary arterial hypertension (PAH). However, the efficacy of MR blockade in established disease, a more clinically relevant condition, remains unknown. Therefore, we investigated the effectiveness of two MR antagonists, eplerenone (EPL) and spironolactone (SPL), after the development of severe right ventricular (RV) dysfunction in the rat SU5416-hypoxia (SuHx) PAH model. Cardiac magnetic resonance imaging (MRI) in SuHx rats at the end of week 5 , before study treatment, confirmed features of established disease including reduced RV ejection fraction and RV hypertrophy, pronounced septal flattening with impaired left ventricular filling and reduced cardiac index. Five weeks of treatment with either EPL or SPL improved left ventricular filling and prevented the further decline in cardiac index compared with placebo. Interventricular septal displacement was reduced by EPL whereas SPL effects were similar, but not significant. Although MR antagonists did not significantly reduce pulmonary artery pressure or vessel remodeling in SuHx rats with established disease, animals with higher drug levels had lower pulmonary pressures. Consistent with effects on cardiac function, EPL treatment tended to suppress MR and proinflammatory gene induction in the RV. In conclusion, MR antagonist treatment led to modest, but consistent beneficial effects on interventricular dependence after the onset of significant RV dysfunction in the SuHx PAH model. These results suggest that measures of RV structure and/or function may be useful endpoints in clinical trials of MR antagonists in patients with PAH.

Pulmonary arterial hypertension (PAH) leads to right ventricular cardiomyopathy and cardiac dysfunctions where in the clinical setting, cardiac arrest is the likely cause of death, in ~70% of PAH patients. We investigated the cardiac phenotype of PAH hearts and tested the hypothesis that the insulin-like hormone, Relaxin could prevent maladaptive cardiac remodeling and protect against cardiac dysfunctions in a PAH animal model. PAH was induced in rats with sugen (20 mg/kg), hypoxia then normoxia (3-weeks/each); relaxin (RLX = 0, 30 or 400 μg/kg/day, n ≥ 6/group) was delivered subcutaneously (6-weeks) with implanted osmotic mini-pumps. Right ventricle (RV) hemodynamics and Doppler-flow measurements were followed by cardiac isolation, optical mapping, and arrhythmia phenotype. Sugen-hypoxia (SuHx) treated rats developed PAH characterized by higher RV systolic pressures (50 ± 19 vs. 22 ± 5 mmHg), hypertrophy, reduced stroke volume, ventricular fibrillation (VF) ( n = 6/11) and bradycardia/arrest ( n = 5/11); both cardiac phenotypes were suppressed with dithiothreitol (DTT = 1 mM) ( n = 0/2/group) or RLX (low or high dose, n = 0/6/group). PAH hearts developed increased fibrosis that was reversed by RLX-HD, but not RLX-LD. Relaxin decreased Nrf2 and glutathione transferases but not glutathione-reductase. High-dose RLX improved pulmonary arterial compliance (measured by Doppler flow), suppressed VF even after burst-pacing, n = 2/6). Relaxin suppressed VF and asystole through electrical remodeling and by reversing thiol oxidative stress. For the first time, we showed two cardiac phenotypes in PAH animals and their prevention by RLX. Relaxin may modulate maladaptive cardiac remodeling in PAH and protect against arrhythmia and cardiac arrest., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Martin, Vanderpool, Henry, Palma, Gabris, Lai, Hu, Tofovic, Reddy, Mora, Gladwin, Romero and Salama.)

The National Heart, Lung, and Blood Institute and the Cardiovascular Medical Research and Education Fund held a workshop on the application of pulmonary vascular disease omics data to the understanding, prevention, and treatment of pulmonary vascular disease. Experts in pulmonary vascular disease, omics, and data analytics met to identify knowledge gaps and formulate ideas for future research priorities in pulmonary vascular disease in line with National Heart, Lung, and Blood Institute Strategic Vision goals. The group identified opportunities to develop analytic approaches to multiomic datasets, to identify molecular pathways in pulmonary vascular disease pathobiology, and to link novel phenotypes to meaningful clinical outcomes. The committee suggested support for interdisciplinary research teams to develop and validate analytic methods, a national effort to coordinate biosamples and data, a consortium of preclinical investigators to expedite target evaluation and drug development, longitudinal assessment of molecular biomarkers in clinical trials, and a task force to develop a master clinical trials protocol for pulmonary vascular disease., Competing Interests: Funding Support and Author Disclosures Several authors report funding support from the National Institutes of Health/National Heart, Lung, and Blood Institute (K08HL128802 to Dr. Oldham; R35HL140019 to Dr. Aldred; R01HL146588 to Dr. Brittain; R01HL135142, R01HL137927, R01HL089856, and R01HL147148 to Dr. Cho; R01HL136603 to Dr. Desai; K01HL146980 to Dr. Kelly; U01HL125215 to Dr. Leopold; and K23HL144418 to Dr. Modena). Dr. Oldham has received a research grant from the Cardiovascular Medical Research and Education Fund. Dr. Leopold was supported by grants from the American Heart Association. Dr. Wilkins was supported by the British Heart Foundation (RE/18/4/34215 and SP/18/10/33975). Dr. Hemnes has served as a consultant for Actelion, Bayer, Complexa, and United Therapeutics; and owns shares in PHPrecisionMed, all outside of the submitted work. Dr. Chan has served as a consultant for Zogenix, Aerpio, and United Therapeutics; is a director, officer, and shareholder in Synhale Therapeutics; has held research grants from Actelion and Pfizer; and has filed patent applications regarding the targeting of BMP signaling and metabolic pathways in pulmonary hypertension, all outside of the submitted work. Dr. Cho has received grant support from Bayer and GlaxoSmithKline; and served as a consultant for Genentech, AstraZeneca, and Illumina, all outside of the submitted work. Dr. Desai has served as a consultant for Novartis, outside of the submitted work. Dr. Modena has received honoraria from AstraZeneca, Genentech, GlaxoSmithKline, Regeneron, Sanofi, and Teva for consulting or lectures in the past; and has current research funding from Genentech and GlaxoSmithKline, all outside of the submitted work. Dr. Rhodes has received personal advisory board fees from Janssen and United Therapeutics, outside of the submitted work. Dr. Wilkins has consulted with Actelion, Novartis, GlaxoSmithKline, and MorphogenIX in the development of biomarkers for pulmonary hypertension, all outside of the submitted work. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2021 American College of Cardiology Foundation. All rights reserved.)

Background: People living with human immunodeficiency virus (PLWH) are at risk of developing pulmonary hypertension (PH) and right ventricular (RV) dysfunction, but understanding of the relationship of RV function to afterload (RV-PA coupling) is limited. We evaluated the clinical and hemodynamic characteristics of human immunodeficiency virus (HIV)-associated PH., Methods: We performed a retrospective review of patients with a diagnosis of HIV undergoing right heart catheterization (RHC) from 2000-2016 in a tertiary care center. Inclusion criteria were diagnosis of HIV, age ≥ 18 years and availability of RHC data. PH was classified as either pulmonary arterial hypertension (PAH; mean pulmonary arterial pressure [mPAP] ≥ 25mmHg with pulmonary artery wedge pressure [PAWP] ≤ 15mmHg) or pulmonary venous hypertension (PVH; mPAP ≥ 25mmHg with PAWP > 15). We collected demographics, CD4 cell count, HIV viral load, RHC and echocardiographic data. The single beat method was used to calculate RV-PA coupling from RHC., Results: Sixty-two PLWH with a clinical likelihood for PH underwent RHC. Thirty-two (52%) met PH criteria (15 with PAH, 17 with PVH). Average time from diagnosis of HIV to diagnosis of PH was 11 years. Eleven of 15 individuals with PAH were on antiretroviral therapy (ART) while all 17 patients with PVH were on ART. Compared to PLWH without PH, those with PH had an increased likelihood of having a detectable HIV viral load and lower CD4 cell counts. PLWH with PAH or PVH had increased RV afterload with normal RV contractility, and preserved RV-PA coupling., Conclusion: PLWH with PH (PAH or PVH) were more likely to have a detectable HIV viral load and lower CD4 count at the time of RHC. PLWH with PAH or PVH had increased RV afterload, normal RV contractility, with preserved RV-PA coupling suggestive of an early onset, mild, and compensated form of PH. These results should be confirmed in larger studies., Competing Interests: The authors have read the journal’s policy, and the authors of the study have the following competing interests to declare: Outside of the present study, MAS received research support from Novartis and Aadi and consultancy fees from Complexa, Actelion, United Therapeutics. AM received support for this study in the form of a grant (number IN-US-300-4452) from Gilead. There are no patents, products in development or marketed products associated with this research to declare. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Using RNAseq, we identified a 61 gene-based circulating transcriptomic profile most correlated with four indices of pulmonary arterial hypertension severity. In an independent dataset, 13/61 (21%) genes were differentially expressed in lung tissues of pulmonary arterial hypertension cases versus controls, highlighting potentially novel candidate genes involved in pulmonary arterial hypertension development., (© The Author(s) 2020.)

Background and Purpose: Tetramethylpyrazine (TMP) was originally isolated from the traditional Chinese herb ligusticum and the fermented Japanese food natto and has since been synthesized. TMP has a long history of beneficial effects in the treatment of many cardiovascular diseases. Here we have evaluated the therapeutic effects of TMP on pulmonary hypertension (PH) in animal models and in patients with pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension (CTEPH)., Experimental Approach: Three well-defined models of PH -chronic hypoxia (10% O 2 )-induced PH (HPH), monocrotaline-induced PH (MCT-PH) and Sugen 5416/hypoxia-induced PH (SuHx-PH) - were used in Sprague-Dawley rats, and assessed by echocardiography, along with haemodynamic and histological techniques. Primary cultures of rat distal pulmonary arterial smooth muscle cells (PASMCs) were used to study intracellular calcium levels. Western blots and RT-qPCR assays were also used. In the clinical cohort, patients with PAH or CTEPH were recruited. The effects of TMP were evaluated in all systems., Key Results: TMP (100 mg·kg -1 ·day -1 ) prevented rats from developing experimental PH and ameliorated three models of established PH: HPH, MCT-PH and SuHx-PH. The therapeutic effects of TMP were accompanied by inhibition of intracellular calcium homeostasis in PASMCs. In a small cohort of patients with PAH or CTEPH, oral administration of TMP (100 mg, t.i.d. for 16 weeks) increased the 6-min walk distance and improved the 1-min heart rate recovery., Conclusion and Implications: Our results suggest that TMP is a novel and inexpensive medication for treatment of PH. Clinical trial is registered with www.chictr.org.cn (ChiCTR-IPR-14005379)., (© 2020 The British Pharmacological Society.)

Objective: Pulmonary hypertension (PH) due to left heart disease (group 2), especially in the setting of heart failure with preserved ejection fraction (HFpEF), is the most common cause of PH worldwide; however, at present, there is no proven effective therapy available for its treatment. PH-HFpEF is associated with insulin resistance and features of metabolic syndrome. The stable prostacyclin analog, treprostinil, is an effective and widely used Food and Drug Administration-approved drug for the treatment of pulmonary arterial hypertension. While the effect of treprostinil on metabolic syndrome is unknown, a recent study suggests that the prostacyclin analog beraprost can improve glucose intolerance and insulin sensitivity. We sought to evaluate the effectiveness of treprostinil in the treatment of metabolic syndrome-associated PH-HFpEF. Approach and Results: Treprostinil treatment was given to mice with mild metabolic syndrome-associated PH-HFpEF induced by high-fat diet and to SU5416/obese ZSF1 rats, a model created by the treatment of rats with a more profound metabolic syndrome due to double leptin receptor defect (obese ZSF1) with a vascular endothelial growth factor receptor blocker SU5416. In high-fat diet-exposed mice, chronic treatment with treprostinil reduced hyperglycemia and pulmonary hypertension. In SU5416/Obese ZSF1 rats, treprostinil improved hyperglycemia with similar efficacy to that of metformin (a first-line drug for type 2 diabetes mellitus); the glucose-lowering effect of treprostinil was further potentiated by the combined treatment with metformin. Early treatment with treprostinil in SU5416/Obese ZSF1 rats lowered pulmonary pressures, and a late treatment with treprostinil together with metformin improved pulmonary artery acceleration time to ejection time ratio and tricuspid annular plane systolic excursion with AMPK (AMP-activated protein kinase) activation in skeletal muscle and the right ventricle., Conclusions: Our data suggest a potential use of treprostinil as an early treatment for mild metabolic syndrome-associated PH-HFpEF and that combined treatment with treprostinil and metformin may improve hyperglycemia and cardiac function in a more severe disease.

Background: Invasive hemodynamic evaluation through right heart catheterization plays an essential role in the diagnosis, categorization, and risk stratification of patients with pulmonary hypertension., Methods: Subjects enrolled in the PVDOMICS (Redefining Pulmonary Hypertension through Pulmonary Vascular Disease Phenomics) program undergo an extensive invasive hemodynamic evaluation that includes repeated measurements at rest and during several provocative physiological challenges. It is a National Institutes of Health/National Heart, Lung, and Blood Institute initiative to reclassify pulmonary hypertension groups based on clustered phenotypic and phenomic characteristics. At a subset of centers, participants also undergo an invasive cardiopulmonary exercise test to assess changes in hemodynamics and gas exchange during exercise., Conclusions: When coupled with other physiological testing and blood -omic analyses involved in the PVDOMICS study, the comprehensive right heart catheterization protocol described here holds promise to clarify the diagnosis and clustering of pulmonary hypertension patients into cohorts beyond the traditional 5 World Symposium on Pulmonary Hypertension groups. This article will describe the methods applied for invasive hemodynamic characterization in the PVDOMICS program. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02980887.

Downregulated expression of K + channels and decreased K + currents in pulmonary artery smooth muscle cells (PASMC) have been implicated in the development of sustained pulmonary vasoconstriction and vascular remodeling in patients with idiopathic pulmonary arterial hypertension (IPAH). However, it is unclear exactly how K + channels are downregulated in IPAH-PASMC. MicroRNAs (miRNAs) are small non-coding RNAs that are capable of posttranscriptionally regulating gene expression by binding to the 3'-untranslated regions of their targeted mRNAs. Here, we report that specific miRNAs are responsible for the decreased K + channel expression and function in IPAH-PASMC. We identified 3 miRNAs (miR-29b, miR-138, and miR-222) that were highly expressed in IPAH-PASMC in comparison to normal PASMC (>2.5-fold difference). Selectively upregulated miRNAs are correlated with the decreased expression and attenuated activity of K + channels. Overexpression of miR-29b, miR-138, or miR-222 in normal PASMC significantly decreased whole cell K + currents and downregulated voltage-gated K + channel 1.5 (K V 1.5/KCNA5) in normal PASMC. Inhibition of miR-29b in IPAH-PASMC completely recovered K + channel function and K V 1.5 expression, while miR-138 and miR-222 had a partial or no effect. Luciferase assays further revealed that K V 1.5 is a direct target of miR-29b. Additionally, overexpression of miR-29b in normal PASMC decreased large-conductance Ca 2+ -activated K + (BK Ca ) channel currents and downregulated BK Ca channel β1 subunit (BK Ca β1 or KCNMB1) expression, while inhibition of miR-29b in IPAH-PASMC increased BK Ca channel activity and BK Ca β1 levels. These data indicate upregulated miR-29b contributes at least partially to the attenuated function and expression of K V and BK Ca channels in PASMC from patients with IPAH.

Despite recent advances, the prognosis of pulmonary hypertension (PH) remains poor. While the initial insult in PH implicates the pulmonary vasculature, the functional state, exercise capacity, and survival of such patients are closely linked to right ventricular (RV) function. In the current study, we sought to investigate the effects of maximum incremental exercise on the matching of RV contractility and afterload (i.e. right ventricular-pulmonary arterial [RV-PA] coupling) in patients with exercise PH (ePH) and pulmonary arterial hypertension (PAH). End-systolic elastance (Ees), pulmonary arterial elastance (Ea), and RV-PA coupling (Ees/Ea) were determined using single-beat pressure-volume loop analysis in 40 patients that underwent maximum invasive cardiopulmonary exercise testing. Eleven patients had ePH, nine had PAH, and 20 were age-matched controls. During exercise, the impaired exertional contractile reserve in PAH was associated with blunted stroke volume index (SVI) augmentation and reduced peak oxygen consumption (peak VO 2 %predicted). Compared to PAH, ePH demonstrated increased RV contractility in response to increasing RV afterload during exercise; however, this was insufficient and resulted in reduced peak RV-PA coupling. The dynamic RV-PA uncoupling in ePH was associated with similarly blunted SVI augmentation and peak VO 2 as PAH. In conclusion, dynamic rest-to-peak exercise RV-PA uncoupling during maximum exercise blunts SV increase and reduces exercise capacity in exercise PH and PAH. In ePH, the insufficient increase in RV contractility to compensate for increasing RV afterload during maximum exercise leads to deterioration of RV-PA coupling. These data provide evidence that even in the early stages of PH, RV function is compromised.

Pulmonary arterial hypertension (PAH) is a life-threatening disease with higher incidence in HIV-infected compared with noninfected patients. SIV-infected NHP develop clinical manifestations of HIV infection, including PAH. To understand the pathogenesis of PAH and determine the relationship between hemodynamic changes and clinical characteristics associated with SIV infection, we performed right heart catheterization and echocardiographic imaging of 21 rhesus macaques before and after SIV infection. Between 6 and 12 mo after infection, 11 of the 21 animals had elevated mean pulmonary arterial pressure (mPAP; greater than 25 mm Hg). RV involvement was evident as increased RV glucose uptake in PAH + macaques on positron emission tomography-coupled CT compared with uninfected animals. RV and pulmonary vascular collagen deposition were elevated in PAH + animals. At 12 mo after infection, 6 of the 21 macaques (28.6%) exhibited continued increase in mPAP (progressive PAH), whereas 5 animals (23.8%) had reduced pressure (transient PAH). SIV infection of rhesus macaques led to 3 distinct outcomes with regard to hemodynamic function. Hemodynamic alterations correlated with specific inflammatory profiles and increased RV and pulmonary arterial fibrosis but not with viral load, sex, or CD4 + T-cell levels. This model of a natural cause of PAH provides insight into disease pathways that are important for the development of novel therapeutic targets.

Despite the increasing trends, reports on long-term follow-up are limited on transitioning from parenteral to oral treprostinil therapy in patients with pulmonary arterial hypertension (PAH). We investigated both the effectiveness of parenteral to oral treprostinil transition and the characteristics associated with transition failure over a duration of two years. The study included 37 Group I functional class I and II patients with PAH on combination therapy. Patients were excluded if cardiac index ≤2.2 L/min/m 2 , right atrial pressure ≥11 mmHg, or 6-min walk distance ≤250 m. Patients were categorized as successful ( S Transition) or unsuccessful ( U Transition) transition based on clinical stability, or a parenteral comparator ( C Parenteral) if they remained on parenteral therapy (no transition). All patients underwent two right heart catheterizations, one at enrollment and a second post transition. Of 24 total transition patients, 46% were classified as U Transition. U Transition occurred on average 577 days post transition. Both U Transition and S Transition had similar hemodynamics at diagnosis and treprostinil dose before and after transition. Before transition, the pulmonary vascular resistance (PVR) was significantly higher in the U Transition (6.7 ± 2 WU) vs. S Transition group (3.5 ± 1.5 WU). At follow-up catheterization, the U Transition group demonstrated further increases in PVR, greater than the C Parenteral group, without recovery despite "rescue" therapy in the U Transition group. A pre-transition PVR of 4.16 WU discriminated the U Transition from the S Transition group. While a subset of PAH patients on combination therapy may be safely transitioned from parenteral to oral treprostinil, caution should be exercised in patients with elevated baseline PVR to avoid irreversible destabilization.

Sickle cell disease (SCD) is associated with intravascular hemolysis and oxidative inhibition of nitric oxide (NO) signaling. BAY 54-6544 is a small-molecule activator of oxidized soluble guanylate cyclase (sGC), which, unlike endogenous NO and the sGC stimulator, BAY 41-8543, preferentially binds and activates heme-free, NO-insensitive sGC to restore enzymatic cGMP production. We tested orally delivered sGC activator, BAY 54-6544 (17 mg/kg/d), sGC stimulator, BAY 41-8543, sildenafil, and placebo for 4-12 weeks in the Berkeley transgenic mouse model of SCD (BERK-SCD) and their hemizygous (Hemi) littermate controls (BERK-Hemi). Right ventricular (RV) maximum systolic pressure (RVmaxSP) was measured using micro right-heart catheterization. RV hypertrophy (RVH) was determined using Fulton's index and RV corrected weight (ratio of RV to tibia). Pulmonary artery vasoreactivity was tested for endothelium-dependent and -independent vessel relaxation. Right-heart catheterization revealed higher RVmaxSP and RVH in BERK-SCD versus BERK-Hemi, which worsened with age. Treatment with the sGC activator more effectively lowered RVmaxSP and RVH, with 90-day treatment delivering superior results, when compared with other treatments and placebo groups. In myography experiments, acetylcholine-induced (endothelium-dependent) and sodium-nitroprusside-induced (endothelium-independent NO donor) relaxation of the pulmonary artery harvested from placebo-treated BERK-SCD was impaired relative to BERK-Hemi but improved after therapy with sGC activator. By contrast, no significant effect for sGC stimulator or sildenafil was observed in BERK-SCD. These findings suggest that sGC is oxidized in the pulmonary arteries of transgenic SCD mice, leading to blunted responses to NO, and that the sGC activator, BAY 54-6544, may represent a novel therapy for SCD-associated pulmonary arterial hypertension and cardiac remodeling.

Background: Right ventricular (RV) diastolic function has been associated with outcomes for patients with pulmonary hypertension; however, the relationship between biomechanics and hemodynamics in the right ventricle has not been studied., Methods and Results: Rat models of RV pressure overload were obtained via pulmonary artery banding (PAB; control, n=7; PAB, n=5). At 3 weeks after banding, RV hemodynamics were measured using a conductance catheter. Biaxial mechanical properties of the RV free wall myocardium were obtained to extrapolate longitudinal and circumferential elastic modulus in low and high strain regions (E 1 and E 2 , respectively). Hemodynamic analysis revealed significantly increased end-diastolic elastance (E ed ) in PAB (control: 55.1 mm Hg/mL [interquartile range: 44.7-85.4 mm Hg/mL]; PAB: 146.6 mm Hg/mL [interquartile range: 105.8-155.0 mm Hg/mL]; P =0.010). Longitudinal E 1 was increased in PAB (control: 7.2 kPa [interquartile range: 6.7-18.1 kPa]; PAB: 34.2 kPa [interquartile range: 18.1-44.6 kPa]; P =0.018), whereas there were no significant changes in longitudinal E 2 or circumferential E 1 and E 2 . Last, wall stress was calculated from hemodynamic data by modeling the right ventricle as a sphere: stress=Pressure×radius2×thickness., Conclusions: RV pressure overload in PAB rats resulted in an increase in diastolic myocardial stiffness reflected both hemodynamically, by an increase in E ed , and biomechanically, by an increase in longitudinal E 1 . Modest increases in tissue biomechanical stiffness are associated with large increases in E ed . Hemodynamic measurements of RV diastolic function can be used to predict biomechanical changes in the myocardium., (© 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.)

Pulmonary hypertension (PH) associated with heart failure with preserved ejection fraction (PH-HFpEF; World Health Organization Group II) secondary to left ventricular (LV) diastolic dysfunction is the most frequent cause of PH. It is an increasingly recognized clinical complication of the metabolic syndrome. To date, no effective treatment has been identified, and no genetically modifiable mouse model is available for advancing our understanding for PH-HFpEF. To develop a mouse model of PH-HFpEF, we exposed 36 mouse strains to 20 weeks of high-fat diet (HFD), followed by systematic evaluation of right ventricular (RV) and LV pressure-volume analysis. The HFD induces obesity, glucose intolerance, insulin resistance, hyperlipidemia, as well as PH, in susceptible strains. We observed that certain mouse strains, such as AKR/J, NON/shiLtJ, and WSB/EiJ, developed hemodynamic signs of PH-HFpEF. Of the strains that develop PH-HFpEF, we selected AKR/J for further model validation, as it is known to be prone to HFD-induced metabolic syndrome and had low variability in hemodynamics. HFD-treated AKR/J mice demonstrate reproducibly higher RV systolic pressure compared with mice fed with regular diet, along with increased LV end-diastolic pressure, both RV and LV hypertrophy, glucose intolerance, and elevated HbA1c levels. Time course assessments showed that HFD significantly increased body weight, RV systolic pressure, LV end-diastolic pressure, biventricular hypertrophy, and HbA1c throughout the treatment period. Moreover, we also identified and validated 129S1/SvlmJ as a resistant mouse strain to HFD-induced PH-HFpEF. These studies validate an HFD/AKR/J mouse model of PH-HFpEF, which may offer a new avenue for testing potential mechanisms and treatments for this disease.

Pulmonary hypertension (PH) is associated with features of obesity and metabolic syndrome that translate to the induction of PH by chronic high-fat diet (HFD) in some inbred mouse strains. We conducted a genome-wide association study (GWAS) to identify candidate genes associated with susceptibility to HFD-induced PH. Mice from 36 inbred and wild-derived strains were fed with regular diet or HFD for 20 weeks beginning at 6-12 weeks of age, after which right ventricular (RV) and left ventricular (LV) end-systolic pressure (ESP) and maximum pressure (MaxP) were measured by cardiac catheterization. We tested for association of RV MaxP and RV ESP and identified genomic regions enriched with nominal associations to both of these phenotypes. We excluded genomic regions if they were also associated with LV MaxP, LV ESP, or body weight. Genes within significant regions were scored based on the shortest-path betweenness centrality, a measure of network connectivity, of their human orthologs in a gene interaction network of human PH-related genes. WSB/EiJ, NON/ShiLtJ, and AKR/J mice had the largest increases in RV MaxP after high-fat feeding. Network-based scoring of GWAS candidates identified epidermal growth factor receptor (Egfr) as having the highest shortest-path betweenness centrality of GWAS candidates. Expression studies of lung homogenate showed that EGFR expression is increased in the AKR/J strain, which developed a significant increase in RV MaxP after high-fat feeding as compared with C57BL/6J, which did not. Our combined GWAS and network-based approach adds evidence for a role for Egfr in murine PH.

Aims: Thrombospondin-1 (TSP1) is a ligand for CD47 and TSP1 -/- mice are protected from pulmonary hypertension (PH). We hypothesized the TSP1-CD47 axis is upregulated in human PH and promotes pulmonary arterial vasculopathy., Methods and Results: We analyzed the molecular signature and functional response of lung tissue and distal pulmonary arteries (PAs) from individuals with (n = 23) and without (n = 16) PH. Compared with controls, lungs and distal PAs from PH patients showed induction of TSP1-CD47 and endothelin-1/endothelin A receptor (ET-1/ETA) protein and mRNA. In control PAs, treatment with exogenous TSP1 inhibited vasodilation and potentiated vasoconstriction to ET-1. Treatment of diseased PAs from PH patients with a CD47 blocking antibody improved sensitivity to vasodilators. Hypoxic wild type (WT) mice developed PH and displayed upregulation of pulmonary TSP1, CD47, and ET-1/ETA concurrent with down regulation of the transcription factor cell homolog of the v-myc oncogene (cMyc). In contrast, PH was attenuated in hypoxic CD47 -/- mice while pulmonary TSP1 and ET-1/ETA were unchanged and cMyc was overexpressed. In CD47 -/- pulmonary endothelial cells cMyc was increased and ET-1 decreased. In CD47 +/+  cells, forced induction of cMyc suppressed ET-1 transcript, whereas suppression of cMyc increased ET-1 signaling. Furthermore, disrupting TSP1-CD47 signaling in pulmonary smooth muscle cells abrogated ET-1-stimulated hypertrophy. Finally, a CD47 antibody given 2 weeks after monocrotaline challenge in rats upregulated pulmonary cMyc and improved aberrations in PH-associated cardiopulmonary parameters., Conclusions: In pre-clinical models of PH CD47 targets cMyc to increase ET-1 signaling. In clinical PH TSP1-CD47 is upregulated, and in both, contributes to pulmonary arterial vasculopathy and dysfunction., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For Permissions, please email: journals.permissions@oup.com.)

Background: Pulmonary hypertension (PH) is associated with poor outcomes, yet specific treatments only exist for a small subset of patients. The most common form of PH is that associated with left heart disease (Group 2), for which there is no approved therapy. Nitrite has shown efficacy in preclinical animal models of Group 1 and 2 PH, as well as in patients with left heart failure with preserved ejection fraction (HFpEF). We evaluated the safety and efficacy of a potentially novel inhaled formulation of nitrite in PH-HFpEF patients as compared with Group 1 and 3 PH., Methods: Cardiopulmonary hemodynamics were recorded after acute administration of inhaled nitrite at 2 doses, 45 and 90 mg. Safety endpoints included change in systemic blood pressure and methemoglobin levels. Responses were also compared with those administered inhaled nitric oxide., Results: Thirty-six patients were enrolled (10 PH-HFpEF, 20 Group 1 pulmonary arterial hypertension patients on background PH-specific therapy, and 6 Group 3 PH). Drug administration was well tolerated. Nitrite inhalation significantly lowered pulmonary, right atrial, and pulmonary capillary wedge pressures, most pronounced in patients with PH-HFpEF. There was a modest decrease in cardiac output and systemic blood pressure. Pulmonary vascular resistance decreased only in Group 3 PH patients. There was substantial increase in pulmonary artery compliance, most pronounced in patients with PH-HFpEF., Conclusions: Inhaled nitrite is safe in PH patients and may be efficacious in PH-HFpEF and Group 3 PH primarily via improvements in left and right ventricular filling pressures and pulmonary artery compliance. The lack of change in pulmonary vascular resistance likely may limit efficacy for Group 1 patients., Trial Registration: ClinicalTrials.gov NCT01431313 FUNDING. This work was supported in part by the NIH grants P01HL103455 (to MAS and MTG), R01HL098032 (to MTG), and R01HL096973 (to MTG), and Mast Therapeutics, Inc., Competing Interests: M.A. Simon has received consultancy fees from United Therapeutics and Gilead. E.L. Parsley is an employee of Mast Therapeutics, Inc. M.T. Gladwin is a coinventor of awarded patent (number 9,387,224) for nitrite therapy for cardiovascular indications. M.T. Gladwin receives sponsored research support for the inhaled nitrite clinical trial (note: M.T.G. does not receive consulting fees from Mast Therapeutics).

Dysregulation of vascular stiffness and cellular metabolism occurs early in pulmonary hypertension (PH). However, the mechanisms by which biophysical properties of the vascular extracellular matrix (ECM) relate to metabolic processes important in PH remain undefined. In this work, we examined cultured pulmonary vascular cells and various types of PH-diseased lung tissue and determined that ECM stiffening resulted in mechanoactivation of the transcriptional coactivators YAP and TAZ (WWTR1). YAP/TAZ activation modulated metabolic enzymes, including glutaminase (GLS1), to coordinate glutaminolysis and glycolysis. Glutaminolysis, an anaplerotic pathway, replenished aspartate for anabolic biosynthesis, which was critical for sustaining proliferation and migration within stiff ECM. In vitro, GLS1 inhibition blocked aspartate production and reprogrammed cellular proliferation pathways, while application of aspartate restored proliferation. In the monocrotaline rat model of PH, pharmacologic modulation of pulmonary vascular stiffness and YAP-dependent mechanotransduction altered glutaminolysis, pulmonary vascular proliferation, and manifestations of PH. Additionally, pharmacologic targeting of GLS1 in this model ameliorated disease progression. Notably, evaluation of simian immunodeficiency virus-infected nonhuman primates and HIV-infected subjects revealed a correlation between YAP/TAZ-GLS activation and PH. These results indicate that ECM stiffening sustains vascular cell growth and migration through YAP/TAZ-dependent glutaminolysis and anaplerosis, and thereby link mechanical stimuli to dysregulated vascular metabolism. Furthermore, this study identifies potential metabolic drug targets for therapeutic development in PH.

Background: Pulmonary hypertension associated with heart failure with preserved ejection fraction (PH-HFpEF) is an increasingly recognized clinical complication of metabolic syndrome. No adequate animal model of PH-HFpEF is available, and no effective therapies have been identified to date. A recent study suggested that dietary nitrate improves insulin resistance in endothelial nitric oxide synthase null mice, and multiple studies have reported that both nitrate and its active metabolite, nitrite, have therapeutic activity in preclinical models of pulmonary hypertension., Methods and Results: To evaluate the efficacy and mechanism of nitrite in metabolic syndrome associated with PH-HFpEF, we developed a 2-hit PH-HFpEF model in rats with multiple features of metabolic syndrome attributable to double-leptin receptor defect (obese ZSF1) with the combined treatment of vascular endothelial growth factor receptor blocker SU5416. Chronic oral nitrite treatment improved hyperglycemia in obese ZSF1 rats by a process that requires skeletal muscle SIRT3-AMPK-GLUT4 signaling. The glucose-lowering effect of nitrite was abolished in SIRT3-deficient human skeletal muscle cells, and in SIRT3 knockout mice fed a high-fat diet, as well. Skeletal muscle biopsies from humans with metabolic syndrome after 12 weeks of oral sodium nitrite and nitrate treatment (IND#115926) displayed increased activation of SIRT3 and AMP-activated protein kinase. Finally, early treatments with nitrite and metformin at the time of SU5416 injection reduced pulmonary pressures and vascular remodeling in the PH-HFpEF model with robust activation of skeletal muscle SIRT3 and AMP-activated protein kinase., Conclusions: These studies validate a rodent model of metabolic syndrome and PH-HFpEF, suggesting a potential role of nitrite and metformin as a preventative treatment for this disease., (© 2016 American Heart Association, Inc.)

Hypoxic pulmonary hypertension (HPH) is initially a disease of the small pulmonary arteries. Its severity is usually quantified by pulmonary vascular resistance (PVR). Acute Rho kinase inhibition has been found to reduce PVR toward control values in animal models, suggesting that persistent pulmonary vasoconstriction is the dominant mechanism for increased PVR. However, HPH may also cause proximal arterial changes, which are relevant to right ventricular (RV) afterload. RV afterload can be quantified by pulmonary vascular impedance, which is obtained via spectral analysis of pulsatile pressure-flow relationships. To determine the effects of HPH independent of persistent pulmonary vasoconstriction in proximal and distal arteries, we quantified pulsatile pressure-flow relationships before and after acute Rho kinase inhibition and measured pulmonary arterial structure with microcomputed tomography. In control lungs, Rho kinase inhibition decreased 0 Hz impedance (Z₀), which is equivalent to PVR, from 2.1 ± 0.4 to 1.5 ± 0.2 mmHg·min·ml⁻¹ (P < 0.05) and tended to increase characteristic impedance (Z(C)) from 0.21 ± 0.01 to 0.22 ± 0.01 mmHg·min·ml⁻¹. In HPH lungs, Rho kinase inhibition decreased Z₀ (P < 0.05) without affecting Z(C). Microcomputed tomography measurements performed on lungs after acute Rho kinase inhibition demonstrated that HPH significantly decreased the unstressed diameter of the main pulmonary artery (760 ± 60 vs. 650 ± 80 μm; P < 0.05), decreased right pulmonary artery compliance, and reduced the frequency of arteries of diameter 50-100 μm (both P < 0.05). These results demonstrate that acute Rho kinase inhibition reverses many but not all HPH-induced changes in distal pulmonary arteries but does not affect HPH-induced changes in the conduit arteries that impact RV afterload.