Aberrant long-chain fatty acid metabolism associated with evolving systemic sclerosis-associated pulmonary arterial hypertension.

We sought to investigate differential metabolism in patients with systemic sclerosis (SSc) who develop pulmonary arterial hypertension (PAH) versus those who do not, as a method of identifying potential disease biomarkers. In a nested case-control design, serum metabolites were assayed in SSc subjects who developed right heart catheterization-confirmed PAH (n = 22) while under surveillance in a longitudinal cohort from Johns Hopkins, then compared with metabolites assayed in matched SSc patients who did not develop PAH (n = 22). Serum samples were collected at "proximate" (within 12 months) and "distant" (within 1-5 yr) time points relative to PAH diagnosis. Metabolites were identified using liquid chromatography-mass spectroscopy (LC-MS). An LC-MS dataset from SSc subjects with either mildly elevated pulmonary pressures or overt PAH from the University of Michigan was compared. Differentially abundant metabolites were tested as predictors of PAH in two additional validation SSc cohorts. Long-chain fatty acid metabolism (LCFA) consistently differed in SSc-PAH versus SSc without PH. LCFA metabolites discriminated SSc-PAH patients with mildly elevated pressures in the Michigan cohort and predicted SSc-PAH up to 2 yr before clinical diagnosis in the Hopkins cohort. Acylcholines containing LCFA residues and linoleic acid metabolites were most important for discriminating SSc-PAH. Combinations of acylcholines and linoleic acid metabolites provided good discrimination of SSc-PAH across cohorts. Aberrant lipid metabolism is observed throughout the evolution of PAH in SSc. Lipidomic signatures of abnormal LCFA metabolism distinguish SSc-PAH patients from those without PH, including before clinical diagnosis and in mild disease.NEW & NOTEWORTHY Abnormal lipid metabolism is evident across time in the development of SSc-PAH, and dysregulated long-chain fatty acid metabolism predicts overt PAH.

Status and Future Directions for Balloon Pulmonary Angioplasty in Chronic Thromboembolic Pulmonary Disease With and Without Pulmonary Hypertension: A Scientific Statement From the American Heart Association.

Balloon pulmonary angioplasty continues to gain traction as a treatment option for patients with chronic thromboembolic pulmonary disease with and without pulmonary hypertension. Recent European Society of Cardiology guidelines on pulmonary hypertension now give balloon pulmonary angioplasty a Class 1 recommendation for inoperable and residual chronic thromboembolic pulmonary hypertension. Not surprisingly, chronic thromboembolic pulmonary hypertension centers are rapidly initiating balloon pulmonary angioplasty programs. However, we need a comprehensive, expert consensus document outlining critical concepts, including identifying necessary personnel and expertise, criteria for patient selection, and a standardized approach to preprocedural planning and establishing criteria for evaluating procedural efficacy and safety. Given this lack of standards, the balloon pulmonary angioplasty skill set is learned through peer-to-peer contact and training. This document is a state-of-the-art, comprehensive statement from key thought leaders to address this gap in the current clinical practice of balloon pulmonary angioplasty. We summarize the current status of the procedure and provide a consensus opinion on the role of balloon pulmonary angioplasty in the overall care of patients with chronic thromboembolic pulmonary disease with and without pulmonary hypertension. We also identify knowledge gaps, provide guidance for new centers interested in initiating balloon pulmonary angioplasty programs, and highlight future directions and research needs for this emerging therapy.

Fatty acid metabolism promotes TRPV4 activity in lung microvascular endothelial cells in pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a morbid disease characterized by significant lung endothelial cell (EC) dysfunction. Prior work has shown that microvascular endothelial cells (MVECs) isolated from animals with experimental PAH and patients with PAH exhibit significant abnormalities in metabolism and calcium signaling. With regards to metabolism, we and others have shown evidence of increased aerobic glycolysis and evidence of increased utilization of alternate fuel sources (such as fatty acids) in PAH EC. In the realm of calcium signaling, our prior work linked increased activity of the transient receptor potential vanilloid-4 (TRPV4) channel to increased proliferation of MVECs isolated from the Sugen/Hypoxia rat model of PAH (SuHx-MVECs). However, the relationship between metabolic shifts and calcium abnormalities was not clear. Specifically, whether shifts in metabolism were responsible for increasing TRPV4 channel activity in SuHx-MVECs was not known. In this study, using human data, serum samples from SuHx rats, and SuHx-MVECs, we describe the consequences of increased MVEC fatty acid oxidation in PAH. In human samples, we observed an increase in long-chain fatty acid levels that was associated with PAH severity. Next, using SuHx rats and SuHx-MVECs, we observed increased intracellular levels of lipids. We also show that increasing intracellular lipid content increases TRPV4 activity, whereas inhibiting fatty acid oxidation normalizes basal calcium levels in SuHx-MVECs. By exploring the fate of fatty acid-derived carbons, we observed that the metabolite linking increased intracellular lipids to TRPV4 activity was ß-hydroxybutyrate (BOHB), a product of fatty acid oxidation. Finally, we show that BOHB supplementation alone is sufficient to sensitize the TRPV4 channel in rat and mouse MVECs. Returning to humans, we observe a transpulmonary BOHB gradient in human patients with PAH. Thus, we establish a link between fatty acid oxidation, BOHB production, and TRPV4 activity in MVECs in PAH. These data provide new insight into metabolic regulation of calcium signaling in lung MVECs in PAH.NEW & NOTEWORTHY In this paper, we explore the link between metabolism and intracellular calcium levels in microvascular endothelial cells (MVECs) in pulmonary arterial hypertension (PAH). We show that fatty acid oxidation promotes sensitivity of the transient receptor potential vanilloid-4 (TRPV4) calcium channel in MVECs isolated from a rodent model of PAH.

Real-world evidence to advance knowledge in pulmonary hypertension: Status, challenges, and opportunities. A consensus statement from the Pulmonary Vascular Research Institute's Innovative Drug Development Initiative's Real-world Evidence Working Group.

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.

Pulmonary Embolism Center of Excellence: Putting It All Together.

Center of excellence (COE) designations are generally used to identify programs with expertise in a specific area of medicine. Meeting criteria for a COE may result in advantages including improved clinical outcomes, marketing advantages, and improved financial performance. However, criteria for COE designations are highly variable, and they are granted by a wide variety of entities. The diagnosis and treatment of both acute pulmonary emboli and chronic thromboembolic pulmonary hypertension are disciplines that require multidisciplinary expertise, highly coordinated care, specialized technology and advanced skillsets gained through high patient volumes.

Periprocedural Complications With Balloon Pulmonary Angioplasty: Analysis of Global Studies.

BACKGROUND: Balloon pulmonary angioplasty (BPA) was introduced as a treatment modality for patients with inoperable, medically refractory chronic thromboembolic pulmonary hypertension decades ago; however, reports of high rates of pulmonary vascular injury have led to considerable refinement in procedural technique. OBJECTIVES: The authors sought to better understand the evolution of BPA procedure-related complications over time. METHODS: The authors conducted a systematic review of original articles published by pulmonary hypertension centers globally and performed a pooled cohort analysis of procedure-related outcomes with BPA. RESULTS: This systematic review identified 26 published articles from 18 countries worldwide from 2013 to 2022. A total of 1,714 patients underwent 7,561 total BPA procedures with an average follow up of 7.3 months. From the first period (2013-2017) to the second period (2018-2022), the cumulative incidence of hemoptysis/vascular injury decreased from 14.1% (474/3,351) to 7.7% (233/3,029) (P < 0.01); lung injury/reperfusion edema decreased from 11.3% (377/3,351) to 1.4% (57/3,943) (P < 0.01); invasive mechanical ventilation decreased from 0.7% (23/3,195) to 0.1% (4/3,062) (P < 0.01); and mortality decreased from 2.0% (13/636) to 0.8% (8/1,071) (P < 0.01). CONCLUSIONS: Procedure-related complications with BPA, including hemoptysis/vascular injury, lung injury/reperfusion edema, mechanical ventilation, and death, were less common in the second period (2018-2022), compared with first period (2013-2017), likely from refinement in patient and lesion selection and procedural technique over time.

Transpulmonary amino acid metabolism in the sugen hypoxia model of pulmonary hypertension.

In pulmonary artery hypertension (PAH), emerging evidence suggests that metabolic abnormalities may be contributing to cellular dysfunction in PAH. Metabolic abnormalities such as glycolytic shift have been observed intracellularly in several cell types in PAH, including microvacular endothelial cells (MVECs). Concurrently, metabolomics of human PAH samples has also revealed a variety of metabolic abnormalities; however the relationship between the intracellular metabolic abnormalities and the serum metabolome in PAH remains under investigation. In this study, we utilize the sugen/hypoxia (SuHx) rodent model of PAH to examine the RV, LV and MVEC intracellular metabolome (using targeted metabolomics) in normoxic and SuHx rats. We additionally validate key findings from our metabolomics experiments with data obtained from cell culture of normoxic and SuHx MVECs, as well as metabolomics of human serum samples from two different PAH patient cohorts. Taken together, our data, spanning rat serum, human serum and primary isolated rat MVECs reveal that: (1) key classes of amino acids (specifically, branched chain amino acids-BCAA) are lower in the pre-capillary (i.e., RV) serum of SuHx rats (and humans); (2) intracellular amino acid levels (in particular BCAAs) are increased in SuHx-MVECs; (3) there may be secretion rather than utilization of amino acids across the pulmonary microvasculature in PAH and (4) an oxidized glutathione gradient is present across the pulmonary vasculature, suggesting a novel fate for increased glutamine uptake (i.e., as a source of glutathione). in MVECs in PAH. In summary, these data reveal new insight into the shifts in amino acid metabolism occurring across the pulmonary circulation in PAH.

Pulmonary Arterial Hypertension in Connective Tissue Diseases Beyond Systemic Sclerosis.

Pulmonary arterial hypertension (PAH) associated with connective tissue disease (CTD) (CTD-PAH) is a devastating condition that may progress rapidly to cause right ventricular dysfunction, resulting in significant morbidity and mortality. The pathobiology, epidemiology, natural history, early diagnosis, and treatment response of PAH associated with scleroderma (SSc-PAH) have been the subjects of intense research efforts over the previous decade. The success of these efforts has resulted in increased awareness and earlier detection of SSc-PAH. Practitioners are less aware of the risk of PAH associated with other CTDs; the aim of this article is to discuss the broader scope of CTD-PAH.

Performance of the DETECT Algorithm for Pulmonary Hypertension Screening in a Systemic Sclerosis Cohort.

OBJECTIVE: Pulmonary arterial hypertension (PAH) is one of the leading causes of mortality in systemic sclerosis (SSc). This study was undertaken to assess predictive accuracies of the DETECT algorithm and the 2015 European Society of Cardiology/European Respiratory Society (ESC/ERS) guidelines in SSc patients who underwent right-sided heart catheterization (RHC) for pulmonary hypertension (PH) evaluation. METHODS: Patients with SSc who had diagnostic RHC, had no PH or had PAH, and had available data on variables to allow application of the DETECT and 2015 ESC/ERS guidelines were included for analysis. PH classification was based on hemodynamics using the 2018 revised criteria and extent of lung fibrosis shown on high-resolution computed tomography. Sensitivity and predictive accuracies of the DETECT algorithm and 2015 ESC/ERS guidelines were calculated, including analysis of subjects with a diffusing capacity for carbon monoxide (DLco) of ≥60% predicted. RESULTS: Sixty-eight patients with SSc had RHC, of whom 58 had no PH and 10 had PAH. The mean age was 60.0 years, and 58.8% had limited cutaneous SSc. The DETECT algorithm had a sensitivity of 1.00 (95% confidence interval [95% CI] 0.69-1.00) and a negative predictive value (NPV) of 1.00 (95% CI 0.80-1.00), whereas the 2015 ESC/ERS guidelines had a sensitivity of 0.80 (95% CI 0.44-0.97) and an NPV of 0.94 (95% CI 0.81-0.99). In patients with a DLco of ≥60% (n = 27), the DETECT algorithm had a sensitivity of 1.00 (95% CI 0.29-1.00) and an NPV of 1.00 (95% CI 0.59-1.00), whereas the 2015 ESC/ERS guidelines had a sensitivity of 0.67 (95% CI 0.09-0.99) and an NPV of 0.94 (95% CI 0.71-1.00). CONCLUSION: The DETECT algorithm has high sensitivity and NPV for diagnosis of PAH, including among individuals with a DLco of ≥60%.

Impact of the revised haemodynamic definition on the diagnosis of pulmonary hypertension in patients with systemic sclerosis.

INTRODUCTION: Pulmonary arterial hypertension (PAH) is one of the leading causes of mortality in systemic sclerosis (SSc). We explored the impact of the updated haemodynamic definition of pulmonary hypertension (PH), as proposed by the 6th World Symposium on Pulmonary Hypertension. METHODS: In this single-centre retrospective analysis, patients with SSc who had right heart catheterisation (RHC) were included. We compared the prior PH definition to the updated PH definition. The prior definition classified PH as mean pulmonary arterial pressure (mPAP) ≥25 mmHg and further divided into pre-capillary PH (PAH and PH due to lung disease and/or hypoxia), post-capillary PH, and combined pre- and post-capillary PH groups. For the updated definition, PH was classified as mPAP >20 mmHg and further divided into the different groups. We validated our findings in the DETECT cohort. RESULTS: Between 2005 and March 2019, 268 RHCs were performed in this single-centre cohort. Using the prior definition, 137 (51%) were diagnosed with PH, with 89 classified as pre-capillary PH (56 with PAH and 33 with PH due to lung disease and/or hypoxia), 29 as post-capillary PH, and 19 as combined pre- and post-capillary PH. When the updated definition was applied to the cohort, seven out of 131 (5%) with no PH were reclassified to pre-capillary PH (PAH (n=1), PH due to lung disease (n=3) and post-capillary PH (n=3)). In those with mPAP 21-24 mmHg, with no left heart or significant lung disease, one out of 28 (4%) in our cohort and four out of 36 (11%) in the DETECT cohort were reclassified as PAH. CONCLUSION: The updated PH definition does not appear to have a significant impact on the diagnosis of PH in two different screening cohorts.

Barriers to physical activity in patients with pulmonary hypertension.

Patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) have low levels of physical activity (PA). Increased PA has health benefits including improved quality of life. This study aimed to identify patient-perceived barriers to PA that correlate with objectively measured PA in this population. We performed a cross-sectional survey of 40 patients with PAH and CTEPH. Participants rated how often 15 barriers interfere with being physically active on a 5-point Likert Scale. The primary outcome measure was PA quantified using the Fitbit Zip activity tracker for two weeks. The primary independent variables were the 15 barriers and a summary score (total average barriers). Separate multivariable linear regressions were performed to assess the association between the 15 barriers and the summary score and PA adjusting for age, sex, and PAH etiology. Of the participants, 85% (34/40) had valid step counts and were included. Of these 34, 85% (n = 29) were female and 91% (n = 31) had PAH. The median (interquartile range [IQR]) number of daily steps was 3913 (2309-6313). The barriers endorsed most strongly were lack of self-discipline, lack of energy, and lack of interest. In the multivariable analysis, a 1-unit increase in perceived lack of interest, lack of enjoyment, and lack of skills was associated with a significant decrease in step counts of -1414 steps (95% confidence interval [CI] = (-2580 - -248), -1458 steps (-2404 - -511), and -1533 steps (-2910 - -156), respectively. Counseling and interventions aimed at increasing PA in patients with PAH should address interest, enjoyment, and skill development.

Ectonucleotidase tri(di)phosphohydrolase-1 (ENTPD-1) disrupts inflammasome/interleukin 1ß-driven venous thrombosis.

Deep vein thrombosis (DVT), caused by alterations in venous homeostasis is the third most common cause of cardiovascular mortality; however, key molecular determinants in venous thrombosis have not been fully elucidated. Several lines of evidence indicate that DVT occurs at the intersection of dysregulated inflammation and coagulation. The enzyme ectonucleoside tri(di)phosphohydrolase (ENTPD1, also known as CD39) is a vascular ecto-apyrase on the surface of leukocytes and the endothelium that inhibits intravascular inflammation and thrombosis by hydrolysis of phosphodiester bonds from nucleotides released by activated cells. Here, we evaluated the contribution of CD39 to venous thrombosis in a restricted-flow model of murine inferior vena cava stenosis. CD39-deficiency conferred a >2-fold increase in venous thrombogenesis, characterized by increased leukocyte engagement, neutrophil extracellular trap formation, fibrin, and local activation of tissue factor in the thrombotic milieu. This was orchestrated by increased phosphorylation of the p65 subunit of NFκB, activation of the NLRP3 inflammasome, and interleukin-1ß (IL-1ß) release in CD39-deficient mice. Substantiating these findings, an IL-1ß-neutralizing antibody attenuated the thrombosis risk in CD39-deficient mice. These data demonstrate that IL-1ß is a key accelerant of venous thrombo-inflammation, which can be suppressed by CD39. CD39 inhibits in vivo crosstalk between inflammation and coagulation pathways, and is a critical vascular checkpoint in venous thrombosis.

Prevalence, Treatment, and Outcomes of Coexistent Pulmonary Hypertension and Interstitial Lung Disease in Systemic Sclerosis.

OBJECTIVE: Systemic sclerosis (SSc) is associated with interstitial lung disease (ILD) and pulmonary hypertension (PH). This study was undertaken to determine the prevalence, characteristics, treatment, and outcomes of PH in a cohort of patients with SSc-associated ILD. METHODS: Patients with SSc-associated ILD on high-resolution computed tomography (HRCT) were included in a prospective observational cohort. Patients were screened for PH based on a standardized screening algorithm and underwent right-sided heart catheterization (RHC) if indicated. PH classification was based on hemodynamic findings and the extent of ILD on HRCT. Summary statistics and survival using the Kaplan-Meier method were calculated. RESULTS: Of the 93 patients with SSc-associated ILD included in the study, 76% were women and 65.6% had diffuse cutaneous SSc. The mean age was 54.9 years, and the mean SSc disease duration was 8 years. Twenty-nine patients (31.2%) had RHC-proven PH; of those 29 patients, 24.1% had PAH, 55.2% had World Health Organization (WHO) Group III PH, 34.5% had WHO Group III PH with pulmonary vascular resistance >3.0 Wood units, 48.3% had a PH diagnosis within 7 years of SSc onset, 82.8% received therapy for ILD, and 82.8% received therapy for PAH. The survival rate 3 years after SSc-associated ILD diagnosis for all patients was 97%. The survival rate 3 years after PH diagnosis for those with SSc-associated ILD and PH was 91%. CONCLUSION: In a large cohort of patients with SSc-associated ILD, a significant proportion of patients had coexisting PH, which often occurs early after SSc diagnosis. Most patients were treated with ILD and PAH therapies, and survival was good. Patients with SSc-associated ILD should be evaluated for coexisting PH.

Nanoparticle-macrophage interactions: A balance between clearance and cell-specific targeting.

The surface properties of nanoparticles (NPs) are a major factor that influences how these nanomaterials interact with biological systems. Interactions between NPs and macrophages of the reticuloendothelial system (RES) can reduce the efficacy of NP diagnostics and therapeutics. Traditionally, to limit NP clearance by the RES system, the NP surface is neutralized with molecules like poly(ethylene glycol) (PEG) which are known to resist protein adsorption and RES clearance. Unfortunately, PEG modification is not without drawbacks including difficulties with the synthesis and associations with immune reactions. To overcome some of these obstacles, we neutralized the NP surface by acetylation and compared this modification to PEGylation for RES clearance and tumor-specific targeting. We found that acetylation was comparable to PEGylation in reducing RES clearance. Additionally, we found that dendrimer acetylation did not impact folic acid (FA)-mediated targeting of tumor cells whereas PEG surface modification reduced the targeting ability of the NP. These results clarify the impact of different NP surface modifications on RES clearance and cell-specific targeting and provide insights into the design of more effective NPs.

Right atrial strain is predictive of clinical outcomes and invasive hemodynamic data in group 1 pulmonary arterial hypertension.

Transthoracic echocardiography (TTE) is a practical and widely used tool for risk stratification in pulmonary arterial hypertension (PAH). We hypothesized that right atrial (RA) reservoir function, represented by peak RA systolic strain, correlates with invasive hemodynamic measurements and clinical outcomes in PAH. Patients with group 1 PAH who had TTE within 6 months of index PAH clinic visit and right heart catheterization were included in this retrospective study. Peak RA strain in the 2D apical 4-chamber view was measured with speckle-tracking software. The primary endpoint was a composite of prostacyclin initiation, lung transplantation, and death. RA strain was also measured in healthy control subjects. Among the 37 patients studied, 25 (68%) met the primary endpoint. RA strain was significantly lower among patients who met the primary endpoint than among those who did not (mean 20% vs. 33%, P = 0.002). Strain was lower in PAH patients than in controls (mean 24% vs. 35%, P = 0.0001). RA strain correlated negatively with hemodynamic data including RA pressure (R = -0.31), mean pulmonary arterial pressure (R = -0.33), and pulmonary vascular resistance (R = -0.39), and positively with cardiac index (R = 0.44). In receiver operating characteristic analysis to distinguish between patients meeting the primary endpoint and event-free survivors, RA strain was not significantly different from RA volume, right ventricular (RV) fractional area change, RV basal diameter, or right ventricular systolic pressure (area under the curve 0.82, 0.81, 0.83, 0.86, and 0.97, respectively). Our results demonstrate that RA strain is predictive of clinical outcomes in PAH. Further research is needed to determine if RA strain is independently associated with outcomes in this population.

Ectonucleotidase CD39-driven control of postinfarction myocardial repair and rupture.

Mechanical complications of myocardial infarction (MI) are often fatal. Little is known about endogenous factors that predispose to myocardial rupture after MI. Ectonucleoside triphosphate diphosphohydrolase (CD39) could be a critical mediator of propensity to myocardial rupture after MI due to its role in modulating inflammation and thrombosis. Using a model of permanent coronary artery ligation, rupture was virtually abrogated in cd39-/- mice versus cd39+/+ controls, with elevated fibrin and collagen deposition and marked neutrophil and macrophage influx. Macrophages were found to display increased surface expression of CD301 and CD206, marking a reparative phenotype, driven by increased extracellular ATP and IL-4 in the infarcted myocardium of cd39-/- mice. A myeloid-specific CD39-knockout mouse also demonstrated protection from rupture, with an attenuated rupture phenotype, suggesting that complete ablation of CD39 provides the greatest degree of protection in this model. Absence of CD39, either globally or in a myeloid lineage-restricted fashion, skews the phenotype toward alternatively activated (reparative) macrophage infiltration following MI. These studies reveal a previously unrecognized and unexpected role of endogenous CD39 to skew macrophage phenotype and promote a propensity to myocardial rupture after MI.

Usefulness of Echocardiography/Doppler to Reliably Predict Elevated Left Ventricular End-Diastolic Pressure in Patients With Pulmonary Hypertension.

The ability of echocardiography (echo)/Doppler to predict elevated left ventricular (LV) end-diastolic pressure (EDP) specifically among patients with pulmonary hypertension is not well defined. This was a retrospective analysis of 161 patients referred to a specialized pulmonary hypertension clinic. A model based on an American Society of Echocardiography (ASE)/European Association of Echocardiography (EAE) joint statement was evaluated, and a new model was developed using univariate linear regression and multivariable logistic regression for potentially better prediction of elevated LVEDP. The study cohort had a median pulmonary arterial pressure was 34.0 mm Hg and pulmonary vascular resistance was 3.7 Wood units; 81 patients (51%) had LVEDP >15 mm Hg on invasive testing. Doppler E/A, E/e' (septal, lateral, and average), e'/a' (lateral and average), and left atrial volume and diameter all had significant correlation with LVEDP (p <0.05). The ASE/EAE model performed poorly (sensitivity 54% and specificity 66%) for detecting elevated LVEDP. Only echo/Doppler grade 3 diastolic dysfunction had an LVEDP significantly different from other grades (grade 0 to 2, median 15 mm Hg, interquartile range 13 to 22 mm Hg; grade 3, median 22 mm Hg, interquartile range 19 to 32 mm Hg; p <0.01). An experimental model was statistically significant in its prediction of elevated LVEDP (area under the receiver operating characteristic curve 0.7, p <0.001) but demonstrated poor performance (sensitivity 67% and specificity 61%). In conclusion, numerous echo/Doppler measurements correlate with elevated LV filling pressure. However, both the ASE/EAE model and our experimental model had poor test performance that did not permit confident identification of elevated LVEDP.

Purinergic dysregulation in pulmonary hypertension.

Despite the fact that nucleotides and adenosine help regulate vascular tone through purinergic signaling pathways, little is known regarding their contributions to the pathobiology of pulmonary arterial hypertension, a condition characterized by elevated pulmonary vascular resistance and remodeling. Even less is known about the potential role that alterations in CD39 (ENTPD1), the ectonucleotidase responsible for the conversion of the nucleotides ATP and ADP to AMP, may play in pulmonary arterial hypertension. In this study we identified decreased CD39 expression on the pulmonary endothelium of patients with idiopathic pulmonary arterial hypertension. We next determined the effects of CD39 gene deletion in mice exposed to normoxia or normobaric hypoxia (10% oxygen). Compared with controls, hypoxic CD39(-/-) mice were found to have a markedly elevated ATP-to-adenosine ratio, higher pulmonary arterial pressures, more right ventricular hypertrophy, more arterial medial hypertrophy, and a pro-thrombotic phenotype. In addition, hypoxic CD39(-/-) mice exhibited a marked increase in lung P2X1 receptors. Systemic reconstitution of ATPase and ADPase enzymatic activities through continuous administration of apyrase decreased pulmonary arterial pressures in hypoxic CD39(-/-) mice to levels found in hypoxic CD39(+/+) controls. Treatment with NF279, a potent and selective P2X1 receptor antagonist, lowered pulmonary arterial pressures even further. Our study is the first to implicate decreased CD39 and resultant alterations in circulating purinergic signaling ligands and cognate receptors in the pathobiology of pulmonary arterial hypertension. Reconstitution and receptor blocking experiments suggest that phosphohydrolysis of purinergic nucleotide tri- and diphosphates, or blocking of the P2X1 receptor could serve as treatment for pulmonary arterial hypertension.