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Purpose/Hypothesis: We previously demonstrated that high intensity interval training (HILT) reduced pulmonary vascular remodeling and increased expression of a key regulator of pulmonary vascular tone, pulmonary endothelial nitric oxide synthase (eNOS) concomitant with alleviation of pulmonary hypertension in a monocrotaline rat model of mild pulmonary arterial hypertension (PAH). Here we investigate pulmonary vascular responses to HILT in a model that elicits a more severe, angioproliferative PAH. Number of Subjects: Forty-five. Materials/Methods: Male Sprague-Dawley rats (-315 g) received a single injection of vascular endothelial growth factor inhibitor Sugen5416 (20 mg/kg) + 3 weeks of hypoxia (Patin = 362 mm Hg) followed by 4 weeks of room air (SuHx, n = 33). Control rats (CON, n = 12) received an injection of saline and remained in room air. A subgroup of SuHx then underwent 6 weeks of treadmill training (in room air) performed as HILT (2 minutes at '-80%-90% VO2Reserve [VO2R] + 3 minutes at 30% VO2R, for 4-5 cycles, n = 12), with the remainder untrained (SED, n = 10). To determine impact of trianing on pulmonary vascular remodeling, Verhoeff—Van Giesson (VVG) immunohistochemical staining was performed on lung sections. Pulmonary vascular wall area was determined from brightfield microscopy images in a blinded fashion for small and medium-sized PAs (<250 p.m diameter, 10 vessels per animal, X20 objective). Measurement of lung total eNOS was performed via electrophoresis and immunoblot analysis of lung homogenates with the intensity of Western blotting bands measured by densitometry (ImageJ software, NIH) and expressed normalized vinculin band intensity. Values are mean ± SE. Results: SuHx-induced elevation in right ventricular systolic pressure (RVSP via Millar catheter in mm Hg) was not improved by HILT (61 ± 7) versus SED (55 ± 8, P > .05), and was higher than CON (28 ± 3, P < .05). SuHx-induced increase in pulmonary arterial wall thickness (as fraction of vessel area) was also not alleviated by HILT (0.43 ± 0.04) versus SED (0.44 ± 0.03, P > .05), and was higher than CON (0.29 ± 0.02, P < .05). HILT did not evoke greater lung eNOS expression in SuHx (0.95 ± 0.03) versus SED (0.94 ± 0.02, P > .05), which tended to be lower than in CON (1.10 ± 0.07, P = .08). Conclusions: In contrast to previous findings in a monocrotaline rat model of mild PAH, HILT does not evoke beneficial pulmonary vascular adaptations nor alleviate pulmonary hypertension in a SuHx rat model of more severe, angioproliferative PAH, sugggesting that responses to training are model- and severity-dependent. Further investigation is needed to optimize training approach for PAH patients with more severe disease. Clinical Relevance: In patients with more severe compli-cations from PAH, HILT may not necessarily improve pulmonary vascular function. Further investigation is needed to optimize training approach for PAH patients with more severe disease. [ABSTRACT FROM AUTHOR]

Purpose/Hypothesis: We previously demonstrated that high intensity interval training (HIIT) approach, but not a continuous exercise training (CET) approach improved right ventricular (RV) function in a monocrotaline rat model of mild pulmonary arterial hypertension (PAH). Here we investigate RV adaptations to HIIT in a model that elicits a more severe, angioproliferative PAH. Number of Subjects: Thirty-nine. Materials/Methods: Sprague–Dawley rats (~315 g, male) received Sugen 5416 (20 mg/kg), followed by 3 weeks of hypoxia and 4 weeks of room air to induce PAH (SuHx, n 5 33). Subgroups of SuHx then underwent 6-weeks of treadmill training performed as either HIIT (2 min 80%–90% VO2 reserve [VO2R] 1 3 min 30% VO2R, for 4–5 cycles, n = 12), or low intensity CET (45–60 min 50% VO2R, n=11), with the remainder untrained (SED, n = 10). Echocardiography to assess RV function was performed at baseline and pre- and post-training. Training impact on RV abundance of apelin-a potent inotropic, anti-apoptotic and anti-inflammatory mediator-was assessed via immunoblotting. Potential adverse RV effects were also investigated, including fibrosis (trichrome), inflammation (CD45 immunostaining) and apoptosis (TUNEL). Values are mean ± SE (Standard Error). Results: SuHx-induced RV hypertrophy (as RV mass/LV+septummass, and as RV thickness on echo in millimeter) was not prevented by HIIT (0.60 ± 0.07, 2.2 ± 0.2) or CET (0.47 ± 0.04, 2.0 ± 0.2), versus SED (0.52±0.06, 2.2±0.2, P<.05), and was higher than untrained healthy controls (CON; n = 6, 0.24 ± 0.01, 1.3 ± 0.1, P < .05). RV apelin (normalized by loading control) was increased in SuHx trained with CET (0.83 ± 0.09) versus SED (0.50 ± 0.03, P < .05), and tended to be increased for HIIT as well (0.78 ± 0.06, P < .10). Abundance of RV apelin for both HIIT- and CETtrained SuHx was similar to CON (0.84 ± 0.05, P > .05). Post-training cardiac output (mL) and stroke volume (mL/ min) was also higher for SuHx trained with either HIIT (239 ± 49, 540 ± 58) or CET (207 ± 41, 529 ± 51) versus SED (122 ± 12, 405 ± 35, P < .05), and were similar to CON (268 ± 59, 548 ± 71, P>.05). However, mortality in SuHx tended to be worse (P=.07) for HIIT (4 deaths at 56, 60, 68, and 71 days), versus CET (2 deaths at 60, and 73 days), and SED (2 deaths at 66 days), and occurred in those with poorer RV function prior to initiation of training. Neither HIIT nor CET increased RV CD45+ or TUNEL+ cell count, or percent of trichrome+ staining versus SED (P > .05), but these assays precluded animals that died unexpectedly early. Conclusions: Training with either HIIT or CET promoted beneficial adaptations of the RV in SuHx rats despite no amelioration of RV hypertrophy. However, in contrast to previous findings in a mild PAH rat model, HIIT tended to promote greater mortality for animals with poorer cardiac function prior to training onset and suggests that further investigation is needed to optimize training approach for patients with more severe RV dysfunction. Clinical Relevance: Training appears to benefit the right ventricle in patients with PAH, but a HIIT approach may not be tolerated for those with more severe disease. [ABSTRACT FROM AUTHOR]

Lung endothelial cells (ECs) are essential for maintaining organ function and homeostasis. Despite sharing some common features with ECs from organ systems, lung ECs exhibit significant heterogeneity in morphology, function, and gene expression. This heterogeneity is increasingly recognized as a key contributor to the development of pulmonary diseases like pulmonary hypertension (PH). In this mini-review, we explore the evolving understanding of lung EC heterogeneity, particularly through the lens of single-cell RNA sequencing (scRNA-seq) technologies. These advances have provided unprecedented insights into the diverse EC subpopulations, their specific roles, and the disturbances in their homeostatic functions that contribute to PH pathogenesis. In particular, these studies identified novel and functionally distinct cell types such as aerocytes and general capillary ECs that are critical for maintaining lung function in health and disease. In addition, multiple novel pathways and mechanisms have been identified that contribute to aberrant pulmonary vascular remodeling in PH. Emerging techniques like single-nucleus RNA sequencing and spatial transcriptomics have further pushed the field forward by discovering novel disease mediators. As research continues to leverage these advanced techniques, the field is poised to uncover novel EC subtypes and disease mechanisms, paving the way for new therapeutic targets in PH and other lung diseases.

Pulmonary vascular disease is not a single condition; rather it can accompany a variety of pathologies that impact the pulmonary vasculature. Applying precision medicine strategies to better phenotype, diagnose, monitor, and treat pulmonary vascular disease is increasingly possible with the growing accessibility of powerful clinical and research tools. Nevertheless, challenges exist in implementing these tools to optimal effect. The 2023 Grover Conference Series reviewed the research landscape to summarize the current state of the art and provide a better understanding of the application of precision medicine to managing pulmonary vascular disease. In particular, the following aspects were discussed: (1) Clinical phenotypes, (2) genetics, (3) epigenetics, (4) biomarker discovery, (5) application of precision biology to clinical trials, (6) the right ventricle (RV), and (7) integrating precision medicine to clinical care. The present review summarizes the content of these discussions and the prospects for the future., Competing Interests: ARH has served as a consultant for United Therapeutics, Bayer, GossamerBio, Merck, Janssen and Tenax Therapeutics and has stock in Tenax Therapeutics. AJ has previously served on an advisory board for Janssen (12/2023. GAH receives funding from Bayer Healthcare: non‐branded Speakers Bureau, Advisory Boards, and Research Funding; and Janssen Pharmaceuticals: Clinical Trial Steering Committee and Advisory Boards., (© 2025 The Author(s). Pulmonary Circulation published by John Wiley & Sons Ltd on behalf of Pulmonary Vascular Research Institute.)

Pulmonary vascular disease (PVD), and in particular, pulmonary hypertension (PH), is a highly specialized area of medicine comprised of complex diagnostics, classification systems, risk assessment tools, and therapeutics, the correct application of which has been shown to impact patient outcomes. The PVD scientific and patient community recognizes the importance of standardization of care patterns and has thus implemented a clinical accreditation process for PH care centers across the United States. However, a similar standardization system is lacking in PVD sub-specialty provider training. Non-Accreditation Council for Graduate Medical Education (ACGME) PVD advanced fellowships exist nationally, but do not provide a unified approach to trainee education. Therefore, first, a survey of all Pulmonary Hypertension Association (PHA)-accredited center directors across the U.S. was performed to gauge interest in a standardized educational initiative in the field of PVD. Second, a NAtional Consortium on PulmOnary VascuLar Disease FeLOwship Training (APOLLO) was founded to establish a common curriculum and set of training requirements across U.S. PVD programs. A particular emphasis was placed on the training requirements for provider competency in PH, because 1) reliable access to PH patients could be supported by all consortium institutions and 2) the consortium members felt that national PH training curriculums lacked standardization and detail. This article provides the results of the national survey, a guideline summary of the fellowship curriculum and training requirements, and a discussion of the impact of the consortium on PVD training and on the PVD subspecialty as a potential emerging formal discipline in internal medicine., (Copyright © 2024. Published by Elsevier Inc.)

Humans living at high-altitude (HA) have adapted to this environment by increasing pulmonary vascular and alveolar growth. RNA sequencing data from a novel murine model that mimics this phenotypical response to HA suggested estrogen signaling via estrogen receptor alpha (ERα) may be involved in this adaptation. We hypothesized ERα was a key mediator in the cardiopulmonary adaptation to chronic hypoxia and sought to delineate the mechanistic role ERα contributes to this process by exposing novel loss-of-function ERα mutant (ERαMut) rats to simulated HA. ERα mutant or wild-type (wt) rats were exposed to normoxia or hypoxia starting at conception and continued postnatally until 6 wk of age. Both wt and ERαMut animals born and raised in hypoxia exhibited lower body mass and higher hematocrits, total alveolar volumes (V a ), diffusion capacities of carbon monoxide (DLCO), pulmonary arteriole (PA) wall thickness, and Fulton indices than normoxia animals. Right ventricle adaptation was maintained in the setting of hypoxia. Although no major physiologic differences were seen between wt and ERαMut animals at either exposure, ERαMut animals exhibited smaller mean linear intercepts (MLI) and increased PA total and lumen areas. Hypoxia exposure or ERα loss-of-function did not affect lung mRNA abundance of vascular endothelial growth factor, angiopoietin 2, or apelin. Sexual dimorphisms were noted in PA wall thickness and PA lumen area in ERαMut rats. In summary, in room air-exposed rats and rats with peri- and postnatal hypoxia exposure, ERα loss-of-function was associated with decreased alveolar size (primarily driven by hypoxic animals) and increased PA remodeling. NEW & NOTEWORTHY By exposing novel loss-of-function estrogen receptor alpha (Erα) mutant rats to a novel model of human high-altitude exposure, we demonstrate that ERα has subtle but inconsistent effects on endpoints relevant to cardiopulmonary adaptation to chronic hypoxia. Given that we observed some histologic, sex, and genotype differences, further research into cell-specific effects of ERα during hypoxia-induced cardiopulmonary adaptation is warranted.

Introduction: Extrapulmonary manifestations of pulmonary arterial hypertension (PAH) may play a critical pathobiological role and a deeper understanding will advance insight into mechanisms and novel therapeutic targets. This manuscript reviews our understanding of extrapulmonary manifestations of PAH., Areas Covered: A group of experts was assembled and a complimentary PubMed search performed (October 2023 - March 2024). Inflammation is observed throughout the central nervous system and attempts at manipulation are an encouraging step toward novel therapeutics. Retinal vascular imaging holds promise as a noninvasive method of detecting early disease and monitoring treatment responses. PAH patients have gut flora alterations and dysbiosis likely plays a role in systemic inflammation. Despite inconsistent observations, the roles of obesity, insulin resistance and dysregulated metabolism may be illuminated by deep phenotyping of body composition. Skeletal muscle dysfunction is perpetuated by metabolic dysfunction, inflammation, and hypoperfusion, but exercise training shows benefit. Renal, hepatic, and bone marrow abnormalities are observed in PAH and may represent both end-organ damage and disease modifiers., Expert Opinion: Insights into systemic manifestations of PAH will illuminate disease mechanisms and novel therapeutic targets. Additional study is needed to understand whether extrapulmonary manifestations are a cause or effect of PAH and how manipulation may affect outcomes.

Pulmonary embolism (PE) is a common and important medical emergency, encountered by clinicians across all acute care specialties. PE is a relatively uncommon cause of direct admission to the intensive care unit (ICU), but these patients are at high risk of death. More commonly, patients admitted to ICU develop PE as a complication of an unrelated acute illness. This paper reviews the epidemiology, diagnosis, risk stratification, and particularly the management of PE from a critical care perspective. Issues around prevention, anticoagulation, fibrinolysis, catheter-based techniques, surgical embolectomy, and extracorporeal support are discussed., (© 2023. Springer-Verlag GmbH Germany, part of Springer Nature.)

Topic Importance: Right ventricular dysfunction in pulmonary hypertension (PH) contributes to reduced exercise capacity, morbidity, and mortality. Exercise can unmask right ventricular dysfunction not apparent at rest, with negative implications for prognosis., Review Findings: Among patients with pulmonary vascular disease, right ventricular afterload may increase during exercise out of proportion to increases observed among healthy individuals. Right ventricular contractility must increase to match the demands of increased afterload to maintain ventricular-arterial coupling (the relationship between contractility and afterload) and ultimately cardiac output. Impaired right ventricular contractile reserve leads to ventricular-arterial uncoupling, preventing cardiac output from increasing during exercise and limiting exercise capacity. Abnormal pulmonary vascular response to exercise can signify early pulmonary vascular disease and is associated with increased mortality. Impaired right ventricular contractile reserve similarly predicts poor outcomes, including reduced exercise capacity and death. Exercise provocation can be used to assess pulmonary vascular response to exercise and right ventricular contractile reserve. Noninvasive techniques (including cardiopulmonary exercise testing, transthoracic echocardiography, and cardiac MRI) as well as invasive techniques (including right heart catheterization and pressure-volume analysis) may be applied selectively to the screening, diagnosis, and risk stratification of patients with suspected or established PH. Further research is required to determine the role of exercise stress testing in the management of pulmonary vascular disease., Summary: This review describes the current understanding of clinical applications of exercise testing in the risk assessment of patients with suspected or established PH., (Copyright © 2023 American College of Chest Physicians. All rights reserved.)

Introduction: Pulmonary arterial hypertension (PAH) is characterised by loss of microvessels. The Wnt pathways control pulmonary angiogenesis but their role in PAH is incompletely understood. We hypothesised that Wnt activation in pulmonary microvascular endothelial cells (PMVECs) is required for pulmonary angiogenesis, and its loss contributes to PAH., Methods: Lung tissue and PMVECs from healthy and PAH patients were screened for Wnt production. Global and endothelial-specific Wnt7a -/- mice were generated and exposed to chronic hypoxia and Sugen-hypoxia (SuHx)., Results: Healthy PMVECs demonstrated >6-fold Wnt7a expression during angiogenesis that was absent in PAH PMVECs and lungs. Wnt7a expression correlated with the formation of tip cells, a migratory endothelial phenotype critical for angiogenesis. PAH PMVECs demonstrated reduced vascular endothelial growth factor (VEGF)-induced tip cell formation as evidenced by reduced filopodia formation and motility, which was partially rescued by recombinant Wnt7a. We discovered that Wnt7a promotes VEGF signalling by facilitating Y1175 tyrosine phosphorylation in vascular endothelial growth factor receptor 2 (VEGFR2) through receptor tyrosine kinase-like orphan receptor 2 (ROR2), a Wnt-specific receptor. We found that ROR2 knockdown mimics Wnt7a insufficiency and prevents recovery of tip cell formation with Wnt7a stimulation. While there was no difference between wild-type and endothelial-specific Wnt7a -/- mice under either chronic hypoxia or SuHx, global Wnt7a +/- mice in hypoxia demonstrated higher pulmonary pressures and severe right ventricular and lung vascular remodelling. Similar to PAH, Wnt7a +/- PMVECs exhibited an insufficient angiogenic response to VEGF-A that improved with Wnt7a., Conclusions: Wnt7a promotes VEGF signalling in lung PMVECs and its loss is associated with an insufficient VEGF-A angiogenic response. We propose that Wnt7a deficiency contributes to progressive small vessel loss in PAH., Competing Interests: Conflict of interest: V.A. de Jesus Perez reports support for the present manuscript from the National Institutes of Health National Heart, Lung, and Blood Institute; and outside the submitted work, holds a leadership position as AHA Chair of Diversity subcommittee. All other authors have nothing to disclose., (Copyright ©The authors 2023.)

Right ventricular (RV) failure is the major determinant of outcome in pulmonary hypertension (PH). Calves exposed to 2-wk hypoxia develop severe PH and unlike rodents, hypoxia-induced PH in this species can lead to right heart failure. We, therefore, sought to examine the molecular and structural changes in the RV in calves with hypoxia-induced PH, hypothesizing that we could identify mechanisms underlying compensated physiological function in the face of developing severe PH. Calves were exposed to 14 days of environmental hypoxia (equivalent to 4,570 m/15,000 ft elevation, n = 29) or ambient normoxia (1,525 m/5,000 ft, n = 25). Cardiopulmonary function was evaluated by right heart catheterization and pressure volume loops. Molecular and cellular determinants of RV remodeling were analyzed by cDNA microarrays, RealTime PCR, proteomics, and immunochemistry. Hypoxic exposure induced robust PH, with increased RV contractile performance and preserved cardiac output, yet evidence of dysregulated RV-pulmonary artery mechanical coupling as seen in advanced disease. Analysis of gene expression revealed cellular processes associated with structural remodeling, cell signaling, and survival. We further identified specific clusters of gene expression associated with 1 ) hypertrophic gene expression and prosurvival mechanotransduction through YAP-TAZ signaling, 2 ) extracellular matrix (ECM) remodeling, 3 ) inflammatory cell activation, and 4 ) angiogenesis. A potential transcriptomic signature of cardiac fibroblasts in RV remodeling was detected, enriched in functions related to cell movement, tissue differentiation, and angiogenesis. Proteomic and immunohistochemical analysis confirmed RV myocyte hypertrophy, together with localization of ECM remodeling, inflammatory cell activation, and endothelial cell proliferation within the RV interstitium. In conclusion, hypoxia and hemodynamic load initiate coordinated processes of protective and compensatory RV remodeling to withstand the progression of PH. NEW & NOTEWORTHY Using a large animal model and employing a comprehensive approach integrating hemodynamic, transcriptomic, proteomic, and immunohistochemical analyses, we examined the early (2 wk) effects of severe PH on the RV. We observed that RV remodeling during PH progression represents a continuum of transcriptionally driven processes whereby cardiac myocytes, fibroblasts, endothelial cells, and proremodeling macrophages act to coordinately maintain physiological homeostasis and protect myocyte survival during chronic, severe, and progressive pressure overload.

Rationale: Genetic studies suggest that SOX17 (SRY-related HMG-box 17) deficiency increases pulmonary arterial hypertension (PAH) risk. Objectives: On the basis of pathological roles of estrogen and HIF2α (hypoxia-inducible factor 2α) signaling in pulmonary artery endothelial cells (PAECs), we hypothesized that SOX17 is a target of estrogen signaling that promotes mitochondrial function and attenuates PAH development via HIF2α inhibition. Methods: We used metabolic (Seahorse) and promoter luciferase assays in PAECs together with the chronic hypoxia murine model to test the hypothesis. Measurements and Main Results: Sox17 expression was reduced in PAH tissues (rodent models and from patients). Chronic hypoxic pulmonary hypertension was exacerbated by mice with conditional Tie2- Sox17 ( Sox17 EC-/- ) deletion and attenuated by transgenic Tie2- Sox17 overexpression ( Sox17 Tg ). On the basis of untargeted proteomics, metabolism was the top pathway altered by SOX17 deficiency in PAECs. Mechanistically, we found that HIF2α concentrations were increased in the lungs of Sox17 EC-/- and reduced in those from Sox17 Tg mice. Increased SOX17 promoted oxidative phosphorylation and mitochondrial function in PAECs, which were partly attenuated by HIF2α overexpression. Rat lungs in males displayed higher Sox17 expression versus females, suggesting repression by estrogen signaling. Supporting 16α-hydroxyestrone (16αOHE; a pathologic estrogen metabolite)-mediated repression of SOX17 promoter activity, Sox17 Tg mice attenuated 16αOHE-mediated exacerbations of chronic hypoxic pulmonary hypertension. Finally, in adjusted analyses in patients with PAH, we report novel associations between a SOX17 risk variant, rs10103692, and reduced plasma citrate concentrations ( n  = 1,326). Conclusions: Cumulatively, SOX17 promotes mitochondrial bioenergetics and attenuates PAH, in part, via inhibition of HIF2α. 16αOHE mediates PAH development via downregulation of SOX17, linking sexual dimorphism and SOX17 genetics in PAH.

Pulmonary hypertension is a progressive and often fatal cardiopulmonary condition characterised by increased pulmonary arterial pressure, structural changes in the pulmonary circulation, and the formation of vaso-occlusive lesions. These changes lead to increased right ventricular afterload, which often progresses to maladaptive right ventricular remodelling and eventually death. Pulmonary arterial hypertension represents one of the most severe and best studied types of pulmonary hypertension and is consistently targeted by drug treatments. The underlying molecular pathogenesis of pulmonary hypertension is a complex and multifactorial process, but can be characterised by several hallmarks: inflammation, impaired angiogenesis, metabolic alterations, genetic or epigenetic abnormalities, influence of sex and sex hormones, and abnormalities in the right ventricle. Current treatments for pulmonary arterial hypertension and some other types of pulmonary hypertension target pathways involved in the control of pulmonary vascular tone and proliferation; however, these treatments have limited efficacy on patient outcomes. This review describes key features of pulmonary hypertension, discusses current and emerging therapeutic interventions, and points to future directions for research and patient care. Because most progress in the specialty has been made in pulmonary arterial hypertension, this review focuses on this type of pulmonary hypertension. The review highlights key pathophysiological concepts and emerging therapeutic directions, targeting inflammation, cellular metabolism, genetics and epigenetics, sex hormone signalling, bone morphogenetic protein signalling, and inhibition of tyrosine kinase receptors., Competing Interests: Competing interests: We have read and understood the BMJ policy on declaration of interests and declare the following interests: none., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

(1) Background: Retinal vascular imaging plays an essential role in diagnosing and managing chronic diseases such as diabetic retinopathy, sickle cell retinopathy, and systemic hypertension. Previously, we have shown that individuals with pulmonary arterial hypertension (PAH), a rare disorder, exhibit unique retinal vascular changes as seen using fluorescein angiography (FA) and that these changes correlate with PAH severity. This study aimed to determine if color fundus (CF) imaging could garner identical retinal information as previously seen using FA images in individuals with PAH. (2) Methods: VESGEN, computer software which provides detailed vascular patterns, was used to compare manual segmentations of FA to CF imaging in PAH subjects (n = 9) followed by deep learning (DL) processing of CF imaging to increase the speed of analysis and facilitate a noninvasive clinical translation. (3) Results: When manual segmentation of FA and CF images were compared using VESGEN analysis, both showed identical tortuosity and vessel area density measures. This remained true even when separating images based on arterial trees only. However, this was not observed with microvessels. DL segmentation when compared to manual segmentation of CF images showed similarities in vascular structure as defined by fractal dimension. Similarities were lost for tortuosity and vessel area density when comparing manual CF imaging to DL imaging. (4) Conclusions: Noninvasive imaging such as CF can be used with VESGEN to provide an accurate and safe assessment of retinal vascular changes in individuals with PAH. In addition to providing insight into possible future clinical translational use.

Pulmonary arterial hypertension (PAH) is characterized by exercise intolerance. Muscle blood flow may be reduced during exercise in PAH; however, this has not been directly measured. Therefore, we investigated blood flow during exercise in a rat model of monocrotaline (MCT)-induced pulmonary hypertension (PH). Male Sprague-Dawley rats (∼200 g) were injected with 60 mg/kg MCT (MCT, n = 23) and vehicle control (saline; CON, n = 16). Maximal rate of oxygen consumption (V̇o 2max ) and voluntary running were measured before PH induction. Right ventricle (RV) morphology and function were assessed via echocardiography and invasive hemodynamic measures. Treadmill running at 50% V̇o 2max was performed by a subgroup of rats (MCT, n = 8; CON, n = 7). Injection of fluorescent microspheres determined muscle blood flow via photo spectroscopy. MCT demonstrated a severe phenotype via RV hypertrophy (Fulton index, 0.61 vs. 0.31; P < 0.001), high RV systolic pressure (51.5 vs. 22.4 mmHg; P < 0.001), and lower V̇o 2max (53.2 vs. 71.8 mL·min -1 ·kg -1 ; P < 0.0001) compared with CON. Two-way ANOVA revealed exercising skeletal muscle blood flow relative to power output was reduced in MCT compared with CON ( P < 0.001), and plasma lactate was increased in MCT (10.8 vs. 4.5 mmol/L; P = 0.002). Significant relationships between skeletal blood flow and blood lactate during exercise were observed for individual muscles ( r = -0.58 to -0.74; P < 0.05). No differences in capillarization were identified. Skeletal muscle blood flow is significantly reduced in experimental PH. Reduced blood flow during exercise may be, at least in part, consequent to reduced exercise intensity in PH. This adds further evidence of peripheral muscle dysfunction and exercise intolerance in PAH.

With severe right ventricular (RV) pressure overload, women demonstrate better clinical outcomes compared with men. The mechanoenergetic mechanisms underlying this protective effect, and their dependence on female endogenous sex hormones, remain unknown. To investigate these mechanisms and their impact on RV systolic and diastolic functional adaptation, we created comparable pressure overload via pulmonary artery banding (PAB) in intact male and female Wistar rats and ovariectomized (OVX) female rats. At 8 wk after surgery, right heart catheterization demonstrated increased RV energy input [indexed pressure-volume area (iPVA)] in all PAB groups, with the greatest increase in intact females. PAB also increased RV energy output [indexed stroke or external work (iEW)] in all groups, again with the greatest increase in intact females. In contrast, PAB only increased RV contractility-indexed end-systolic elastance (i E es )] in females. Despite these sex-dependent differences, no statistically significant effects were observed in the ratio of RV energy output to input (mechanical efficiency) or in mechanoenergetic cost to pump blood with pressure overload. These metrics were similarly unaffected by loss of endogenous sex hormones in females. Also, despite sex-dependent differences in collagen content and organization with pressure overload, decreases in RV compliance and relaxation time constant (tau Weiss) were not determined to be sex dependent. Overall, despite sex-dependent differences in RV contractile and fibrotic responses, RV mechanoenergetics for this degree and duration of pressure overload are comparable between sexes and suggest a homeostatic target. NEW & NOTEWORTHY Sex differences in right ventricular mechanical efficiency and energetic adaptation to increased right ventricular afterload were measured. Despite sex-dependent differences in contractile and fibrotic responses, right ventricular mechanoenergetic adaptation was comparable between the sexes, suggesting a homeostatic target.

Pulmonary arterial hypertension (PAH) is classically considered an isolated small vessel vasculopathy of the lungs with peripheral pulmonary vascular obliteration. Systemic manifestations of PAH are increasingly acknowledged, but data remain limited. We hypothesized that retinal vascular changes occur in PAH. PAH subjects underwent retinal fluorescein angiography (FA) and routine disease severity measures were collected from the medical record. FA studies were analyzed using VESsel GENerational Analysis (VESGEN), a noninvasive, user-interactive computer software that assigns branching generation to large and small vessels. FAs from controls ( n  = 8) and PAH subjects ( n  = 9) were compared. The tortuosity of retinal arteries was higher in PAH subjects compared to unmatched controls (1.17, 95% confidence interval: [1.14, 1.20] in PAH vs. 1.13, 95% CI: [1.12, 1.14] in controls, p  = 0.01). Venous tortuosity was higher and more variable in PAH (1.17, 95% CI: [1.14, 1.20]) compared to controls (1.13, 95% CI: [1.12, 1.15]), p  = 0.02. PAH subjects without connective tissue disease had the highest degree of retinal tortuosity relative to controls (arterial, p  = 0.01; venous, p  = 0.03). Younger PAH subjects had greater retinal arterial tortuosity, which attenuated with age and was not observed in controls. Retinal vascular parameters correlated with some clinical measures of disease in PAH subjects. In conclusion, PAH subjects exhibit higher retinal vascular tortuosity. Retinal vascular changes may track with pulmonary vascular disease progression. Use of FA and VESGEN may facilitate early, noninvasive detection of PAH., Competing Interests: Corey E. Ventetuolo has served as a consultant to Altavant Sciences, Acceleron Pharma and United Therapeutics and received support from Altavant Sciences to her institution for the conduct of a clinical trial. The remainder of the authors have no conflicts to declare., (© 2022 The Authors. Pulmonary Circulation published by John Wiley & Sons Ltd on behalf of Pulmonary Vascular Research Institute.)

Gymnocypris dobula , classified into the highly specialized Schizothoracine fish, is endemic to Tibet, China. The complete mitochondrial DNA sequence of G. dobula was 16,728 base pairs in length and comprised 22 transfer RNA genes, 13 protein-coding genes, two ribosomal RNA genes as well as one control region as in a typical vertebrate mitochondrial DNA gene. The ML and BI trees showed that G. dobula was most closely related to Gymnocypris scleracanthus within the highly specialized group. This mitogenome provides new molecular data for further taxonomic and phylogenetic studies of Schizothoracine fish., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

G protein-coupled receptors (GPCRs) have originally been described as a family of receptors activated by hormones, neurotransmitters, and other mediators. However, in recent years GPCRs have shown to bind endogenous metabolites, which serve functions other than as signaling mediators. These receptors respond to fatty acids, mono- and disaccharides, amino acids, or various intermediates and products of metabolism, including ketone bodies, lactate, succinate, or bile acids. Given that many of these metabolic processes are dysregulated under pathological conditions, including diabetes, dyslipidemia, and obesity, receptors of endogenous metabolites have also been recognized as potential drug targets to prevent and/or treat metabolic and cardiovascular diseases. This review describes G protein-coupled receptors activated by endogenous metabolites and summarizes their physiological, pathophysiological, and potential pharmacological roles.

Rationale: Androgens are potentially beneficial in asthma, but AR (androgen receptor) has not been studied in human airways. Objectives: To measure whether AR and its ligands are associated with human asthma outcomes. Methods: We compared the effects of AR expression on lung function, symptom scores, and fractional exhaled nitric oxide (Fe NO ) in adults enrolled in SARP (Severe Asthma Research Program). The impact of sex and of androgens on asthma outcomes was also evaluated in the SARP with validation studies in the Cleveland Clinic Health System and the NHANES (U.S. National Health and Nutrition Examination Survey). Measurements and Main Results: In SARP ( n  = 128), AR gene expression from bronchoscopic epithelial brushings was positively associated with both FEV 1 /FVC ratio ( R 2  = 0.135, P  = 0.0002) and the total Asthma Quality of Life Questionnaire score ( R 2  = 0.056, P  = 0.016) and was negatively associated with Fe NO ( R 2  = 0.178, P  = 9.8 × 10 -6 ) and NOS2 (nitric oxide synthase gene) expression ( R 2  = 0.281, P  = 1.2 × 10 -10 ). In SARP ( n  = 1,659), the Cleveland Clinic Health System ( n  = 32,527), and the NHANES ( n  = 2,629), women had more asthma exacerbations and emergency department visits than men. The levels of the AR ligand precursor dehydroepiandrosterone sulfate correlated positively with the FEV 1 in both women and men. Conclusions: Higher bronchial AR expression and higher androgen levels are associated with better lung function, fewer symptoms, and a lower Fe NO in human asthma. The role of androgens should be considered in asthma management.

Right ventricular dysfunction is a hallmark of advanced pulmonary vascular, lung parenchymal, and left heart disease, yet the underlying mechanisms that govern (mal)adaptation remain incompletely characterized. Owing to the knowledge gaps in our understanding of the right ventricle (RV) in health and disease, the National Heart, Lung, and Blood Institute (NHLBI) commissioned a working group to identify current challenges in the field. These included a need to define and standardize normal RV structure and function in populations; access to RV tissue for research purposes and the development of complex experimental platforms that recapitulate the in vivo environment; and the advancement of imaging and invasive methodologies to study the RV within basic, translational, and clinical research programs. Specific recommendations were provided, including a call to incorporate precision medicine and innovations in prognosis, diagnosis, and novel RV therapeutics for patients with pulmonary vascular disease., Competing Interests: Conflict of Interest Statement Dr. Aggarwal has nothing to disclose. Dr. Aldred reports grants from NHLBI during the conduct of the study. Dr. Archer has nothing to disclose. Dr. Benza reports grants from Abbott during the conduct of the study; grants from Actelion, grants from United Therapeutics, grants from Bayer, grants from NIH/NHLBI outside the submitted work. Dr. Bristow has nothing to disclose. Dr. Brittain has nothing to disclose. Dr. Chesler reports personal fees from Endotronix, Inc. and personal fees from Aria CV outside the submitted work. Dr. de Man has nothing to disclose. Dr. Erzurum has nothing to disclose. Dr. Gladwin is a co-inventor of patents and patent applications directed to the use of recombinant neuroglobin and heme-based molecules as antidotes for CO poisoning, which have been licensed by Globin Solutions, Inc. Dr. Gladwin is a shareholder, advisor, and director in Globin Solutions, Inc. Dr. Gladwin is also co-inventor on patents directed to the use of nitrite salts in cardiovascular diseases, which were previously licensed to United Therapeutics, and is now licensed to Globin Solutions and Hope Pharmaceuticals. Dr. Gladwin is a principal investigator in a research collaboration with Bayer Pharmaceuticals to evaluate riociguat as a treatment for patients with SCD. Dr. Gladwin has served as a consultant for Epizyme, Inc., Actelion Clinical Research, Inc., Acceleron Pharma, Inc., Catalyst Biosciences, Inc., Modus Therapeutics, Sujana Biotech, LLC, Complexa Inc., Pfizer Inc., and United Therapeutics Corporation. Dr. Gladwin is also on Bayer HealthCare LLC’s Heart and Vascular Disease Research Advisory Board. Dr. Hemnes reports personal fees from Actelion, personal fees from Bayer, personal fees from Complexa, personal fees from United Therapeutics, other from PHPrecisionMed, outside the submitted work. Dr. Hassoun has served on an advisory board for Merck in 2019. Dr. Kawut reports grants from NIH, non-financial support from the ATS, and grants from Actelion, United Therapeutics, Gilead, Lung Biotech, Bayer, and Mallinkrodt to the Perelman School of Medicine for CME courses. Dr. Kawut reports grants and non-financial support from Cardiovascular Medical Research and Education Fund and non-financial support from Pulmonary Hypertension Association. Dr. Kawut has served in an advisory capacity (for grant review and other purposes) for United Therapeutics, Glaxo SmithKline, and Complexa, Inc. without financial support or in-kind benefits. Dr. Lahm reports personal fees from Bayer, personal fees from Gilead, personal fees from Actelion, other from Eli Lilly outside the submitted work. Dr. Leopold has nothing to disclose. Dr. Lima has nothing to disclose. Dr. Loscalzo is a scientific co-founder of Scipher, a startup company that uses network concepts to explore human disease treatment strategies. Dr. Maron reports other from Actelion Pharmaceuticals Inc., outside the submitted work. In addition, Dr. Maron has a patent U.S. Patent #9,605,047 issued, a patent U.S. Provisional Application ID: 62475955 pending, a patent U.S. Provisional Application Cover Sheet ID: 24624 pending, and a patent U.S. Patent application PCT/US2019/059890 pending. Dr. Mercer-Rosa has nothing to disclose. Dr. Newman has nothing to disclose. Dr. Redline reports grants and personal fees from Jazz Pharmaceuticals, personal fees from RespirCardia Inc. outside the submitted work. Dr. Rich has nothing to disclose. Dr. Rischard has nothing to disclose. Dr. Sugeng has nothing to disclose. Dr. Tang reports grants from National Institutes of Health, personal fees from Sequana Medical Inc, personal fees from Springer, personal fees from MyoKardia Inc outside the submitted work. Dr Tedford reports other from Actelion, other from Merck, personal fees from United Therapeutics, personal fees from Aria CV, personal fees from Arena pharmaceuticals, personal fees from Gradient, personal fees from Eidos Therapeutics, personal fees and other from Abbott, personal fees and other from Medtronic, personal fees from Itamar, other from Abiomed, and personal fees and other from Acceleron outside the submitted work. Dr. Tsai reports grants from National Heart, Lung, and Blood Institute (NHLBI), grants from American College of Cardiology, grants from The Rachel and Drew Katz Foundation outside the submitted work. In addition, Dr. Tsai has a patent Pharmacologic Treatment for Right Ventricular Failure (USSN 62/836,315) issued to The Trustees of Columbia University in the City of New York. Dr. Ventetuolo reports grants from NHLBI during the conduct of the study; grants from United Therapeutics, grants from American Thoracic Society, personal fees from Acceleron Pharma, personal fees from Bayer outside the submitted work. Dr. Lei Xiao has no conflict of interest to disclose. Dr. Zhao has nothing to disclose.

Pulmonary arterial hypertension (PAH) is a sex-biased disease. Increased expression and activity of the long-noncoding RNA X-inactive-specific transcript (Xist), essential for X-chromosome inactivation and dosage compensation of X-linked genes, may explain the sex bias of PAH. The present studies used a murine model of plexiform PAH, the intersectin-1s (ITSN) heterozygous knockout (KO ITSN+/- ) mouse transduced with an ITSN fragment (EH ITSN ) possessing endothelial cell proliferative activity, in conjunction with molecular, cell biology, biochemical, morphologic, and functional approaches. The data demonstrate significant sex-centered differences with regard to EH ITSN -induced alterations in pulmonary artery remodeling, lung hemodynamics, and p38/ETS domain containing protein/c-Fos signaling, altogether leading to a more severe female lung PAH phenotype. Moreover, the long-noncoding RNA-Xist is up-regulated in the lungs of female EH ITSN -KO ITSN+/- mice compared with that in female wild-type mice, leading to sex-specific modulation of the X-linked gene ETS domain containing protein and its target, two molecular events also characteristic to female human PAH lung. More importantly, cyclin A1 expression in the S and G 2 /M phases of the cell cycle of synchronized pulmonary artery endothelial cells of female PAH patients is greater versus controls, suggesting functional hyperproliferation. Thus, Xist up-regulation leading to female pulmonary artery endothelial cell sexual dimorphic behavior may provide a better understanding of the origin of sex bias in PAH. Notably, the EH ITSN -KO ITSN+/- mouse is a unique experimental animal model of PAH that recapitulates most of the sexually dimorphic characteristics of human disease., (Copyright © 2021 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Pulmonary arterial hypertension (PAH) affects more women than men, although affected females tend to survive longer than affected males. This sex disparity in PAH is postulated to stem from the diverse roles of sex hormones in disease etiology. In animal models, estrogens appear to be implicated not only in pathologic remodeling of pulmonary arteries, but also in protection against right ventricular (RV) hypertrophy. In contrast, the male sex hormone testosterone is associated with reduced survival in male animals, where it is associated with increased RV mass, volume, and fibrosis. However, it also has a vasodilatory effect on pulmonary arteries. Furthermore, patients of both sexes show varying degrees of response to current therapies for PAH. As such, there are many gaps and contradictions regarding PAH development, progression, and therapeutic interventions in male versus female patients. Many of these questions remain unanswered, which may be due in part to lack of effective experimental models that can consistently reproduce PAH pulmonary microenvironments in their sex-specific forms. This review article summarizes the roles of estrogens and related sex hormones, immunological and genetical differences, and the benefits and limitations of existing experimental tools to fill in gaps in our understanding of the sex-based variation in PAH development and progression. Finally, we highlight the potential of a new tissue chip-based model mimicking PAH-afflicted male and female pulmonary arteries to study the sex-based differences in PAH and to develop personalized therapies based on patient sex and responsiveness to existing and new drugs.

Background: The renin-angiotensin-aldosterone system (RAAS) contributes to pulmonary hypertension (PH) pathogenesis. Although animal data suggest that RAAS inhibition attenuates PH, it is unknown if RAAS inhibition is beneficial in PH patients., Research Question: Is RAAS inhibitor use associated with lower mortality in a large cohort of patients with hemodynamically confirmed PH?, Study Design and Methods: We used the Department of Veterans Affairs Clinical Assessment Reporting and Tracking Database to study retrospectively relationships between RAAS inhibitors (angiotensin converting enzyme inhibitors [ACEIs], angiotensin receptor blockers [ARBs], and aldosterone antagonists [AAs]) and mortality in 24,221 patients with hemodynamically confirmed PH. We evaluated relationships in the full and in propensity-matched cohorts. Analyses were adjusted for demographics, socioeconomic status, comorbidities, disease severity, and comedication use in staged models., Results: ACEI and ARB use was associated with improved survival in unadjusted Kaplan-Meier survival analyses in the full cohort and the propensity-matched cohort. This relationship was insensitive to adjustment, independent of pulmonary artery wedge pressure, and also was observed in a cohort restricted to individuals with precapillary PH. AA use was associated with worse survival in unadjusted Kaplan-Meier survival analyses in the full cohort; however, AA use was associated less robustly with mortality in the propensity-matched cohort and was not associated with worse survival after adjustment for disease severity, indicating that AAs in real-world practice are used preferentially in sicker patients and that the unadjusted association with increased mortality may be an artifice of confounding by indication of severity., Interpretation: ACEI and ARB use is associated with lower mortality in veterans with PH. AA use is a marker of disease severity in PH. ACEIs and ARBs may represent a novel treatment strategy for diverse PH phenotypes., (Copyright © 2020. Published by Elsevier Inc.)

Women with pulmonary arterial hypertension (PAH) exhibit better right ventricular (RV) function and survival than men; however, the underlying mechanisms are unknown. We hypothesized that 17β-estradiol (E2), through estrogen receptor α (ER-α), attenuates PAH-induced RV failure (RVF) by upregulating the procontractile and prosurvival peptide apelin via a BMPR2-dependent mechanism. We found that ER-α and apelin expression were decreased in RV homogenates from patients with RVF and from rats with maladaptive (but not adaptive) RV remodeling. RV cardiomyocyte apelin abundance increased in vivo or in vitro after treatment with E2 or ER-α agonist. Studies employing ER-α-null or ER-β-null mice, ER-α loss-of-function mutant rats, or siRNA demonstrated that ER-α is necessary for E2 to upregulate RV apelin. E2 and ER-α increased BMPR2 in pulmonary hypertension RVs and in isolated RV cardiomyocytes, associated with ER-α binding to the Bmpr2 promoter. BMPR2 is required for E2-mediated increases in apelin abundance, and both BMPR2 and apelin are necessary for E2 to exert RV-protective effects. E2 or ER-α agonist rescued monocrotaline pulmonary hypertension and restored RV apelin and BMPR2. We identified what we believe to be a novel cardioprotective E2/ER-α/BMPR2/apelin axis in the RV. Harnessing this axis may lead to novel RV-targeted therapies for PAH patients of either sex.