Characterization and regulation of wild‐type and mutant TASK‐1 two pore domain potassium channels indicated in pulmonary arterial hypertension

Key points The TASK-1 channel gene (KCNK3) has been identified as a possible disease-causing gene in heritable pulmonary arterial hypertension (PAH). In the present study, we show that novel mutated TASK-1 channels, seen in PAH patients, have a substantially reduced current compared to wild-type TASK-1 channels. These mutated TASK-1 channels are located at the plasma membrane to the same degree as wild-type TASK-1 channels. ONO-RS-082 and alkaline pH 8.4 both activate TASK-1 channels but do not recover current through mutant TASK-1 channels. We show that the guanylate cyclase activator, riociguat, a novel treatment for PAH, enhances current through TASK-1 channels but does not recover current through mutant TASK-1 channels. Pulmonary arterial hypertension (PAH) affects ∼15–50 people per million. KCNK3, the gene that encodes the two pore domain potassium channel TASK-1 (K2P3.1), has been identified as a possible disease-causing gene in heritable PAH. Recently, two new mutations have been identified in KCNK3 in PAH patients: G106R and L214R. The present study aimed to characterize the functional properties and regulation of wild-type (WT) and mutated TASK-1 channels and determine how these might contribute to PAH and its treatment. Currents through WT and mutated human TASK-1 channels transiently expressed in tsA201 cells were measured using whole-cell patch clamp electrophysiology. Localization of fluorescence-tagged channels was visualized using confocal microscopy and quantified with in-cell and on-cell westerns. G106R or L214R mutated channels were located at the plasma membrane to the same degree as WT channels; however, their current was markedly reduced compared to WT TASK-1 channels. Functional current through these mutated channels could not be restored using activators of WT TASK-1 channels (pH 8.4, ONO-RS-082). The guanylate cyclase activator, riociguat, enhanced current through WT TASK-1 channels; however, similar to the other activators investigated, riociguat did not have any effect on current through mutated TASK-1 channels. Thus, novel mutations in TASK-1 seen in PAH substantially alter the functional properties of these channels. Current through these channels could not be restored by activators of TASK-1 channels. Riociguat enhancement of current through TASK-1 channels could contribute to its therapeutic benefit in the treatment of PAH

Historical Archaeology in the Iberian Peninsula

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An open-label, dose-escalation study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of single doses of GSK2586881 in participants with pulmonary arterial hypertension

Arterial hypertension; Hemodynamics; Renin‐angiotensin systemHipertensión arterial; Hemodinámica; Sistema renina-angiotensinaHipertensió arterial; Hemodinàmica; Sistema renina-angiotensinaPreclinical and early clinical studies suggest that angiotensin-converting enzyme type 2 activity may be impaired in patients with pulmonary arterial hypertension (PAH); therefore, administration of exogenous angiotensin-converting enzyme type 2 (ACE2) may be beneficial. This Phase IIa, multi-center, open-label, exploratory, single-dose, dose-escalation study (NCT03177603) assessed the potential vasodilatory effects of single doses of GSK2586881 (a recombinant human ACE2) on acute cardiopulmonary hemodynamics in hemodynamically stable adults with documented PAH who were receiving background PAH therapy. Successive cohorts of participants were administered a single intravenous dose of GSK2586881 of 0.1, 0.2, 0.4, or 0.8 mg/kg. Dose escalation occurred after four or more participants per cohort were dosed and a review of safety, tolerability, pharmacokinetics, and hemodynamic data up to 24 h postdose was undertaken. The primary endpoint was a change in cardiopulmonary hemodynamics (pulmonary vascular resistance, cardiac index, and mean pulmonary artery pressure) from baseline. Secondary/exploratory objectives included safety and tolerability, effect on renin-angiotensin system peptides, and pharmacokinetics. GSK2586881 demonstrated no consistent or sustained effect on acute cardiopulmonary hemodynamics in participants with PAH receiving background PAH therapy (N = 23). All doses of GSK2586881 were well tolerated. GSK2586881 was quantifiable in plasma for up to 4 h poststart of infusion in all participants and caused a consistent and sustained reduction in angiotensin II and a corresponding increase in angiotensin (1–7) and angiotensin (1–5). While there does not appear to be a consistent acute vasodilatory response to single doses of GSK2586881 in participants with PAH, the potential benefits in terms of chronic vascular remodeling remain to be determined

Characterisation and regulation of wild type and mutant TASK-1 two pore domain potassium channels indicated in pulmonary arterial hypertension

KEY POINTS SUMMARY The TASK-1 channel gene (KCNK3) has been identified as a possible disease-causing gene in heritable pulmonary arterial hypertension (PAH). In this study we show that novel mutated TASK-1 channels, seen in PAH patients, have a substantially reduced current compared to wild type TASK-1 channels. These mutated TASK-1 channels are located at the plasma membrane to the same degree as wild type TASK-1 channels. ONO-RS-082 and alkaline pH 8.4 both activate TASK-1 channels but do not recover current through mutant TASK-1 channels. We show that the guanylate cyclase activator, riociguat, a novel treatment for PAH, enhances current through TASK-1 channels but does not recover current through mutant TASK-1 channels. ABSTRACT Pulmonary arterial hypertension (PAH) affects approximately 15-50 people per million. KCNK3, the gene that encodes the two pore domain potassium channel TASK-1 (K2P3.1), has been identified as a possible disease-causing gene in heritable PAH. Recently two new mutations have been identified in KCNK3, G106R and L214R, in PAH patients. The aim of this study is to characterise the functional properties and regulation of wildtype (WT) and mutated TASK-1 channels and understand how these might contribute to PAH and its treatment. Currents through WT and mutated human TASK-1 channels transiently expressed in tsA201 cells were measured using whole-cell patch-clamp electrophysiology. Localisation of fluorescently-tagged channels was visualised using confocal microscopy and quantified with in-cell and on-cell Westerns. G106R or L214R mutated channels were located at the plasma membrane to the same degree as WT channels, however their current was markedly reduced compared to WT TASK-1 channels. Functional current through these mutated channels could not be restored using activators of WT TASK-1 channels (pH 8.4, ONO-RS-082). The guanylate cyclase activator, riociguat, enhanced current through WT TASK-1 channels, however, like the other activators investigated, riociguat did not have any effect on current through mutated TASK-1 channels. Thus, novel mutations in TASK-1 seen in PAH, substantially alter the functional properties of these channels. Current through these channels could not be restored by activators of TASK-1 channels. Riociguat enhancement of current through TASK-1 channels could contribute to its therapeutic benefit in the treatment of PAH

Changes in REVEAL risk score in patients with pulmonary arterial hypertension treated with macitentan in clinical practice: results from the PRACMA study

Background: Macitentan is a dual endothelin receptor antagonist indicated for the long-term treatment of pulmonary arterial hypertension (PAH). We evaluated the change over time in REVEAL risk score in incident and prevalent patients receiving macitentan for the first time. Methods: Retrospective, observational study including adult patients with idiopathic/heritable PAH or PAH associated with connective tissue disorders or congenital heart disease treated with macitentan for ≥6-month follow-up in Spain. The REVEAL risk score and risk strata were computed at the start of macitentan and after ≥6-month in patients with ≥7 out of 12 valid REVEAL components. Results: Overall, 81 patients (57 for the REVEAL score) were analysed, 77.8% women. The mean age was 57.2 years and 50.6% of patients had idiopathic/heritable PAH. Prevalent patients were 59.3 and 40.7% were incident. Main therapies for PAH included macitentan monotherapy (42.0%) and macitentan in combination with phosphodiesterase type 5 inhibitor (44.4%). With a median time of macitentan treatment of 10.5 months, the mean REVEAL score was 8.7 points at baseline and was 7.2 points after ≥6-month follow-up. The mean change (95% CI) in REVEAL risk score was - 1.4 (- 2.0, - 0.9) points (p < 0.0001), being - 1.8 (- 3.0, - 0.7) points (p = 0.0040) and - 1.2 (- 1.8, - 0.5) points (p = 0.0010), in incident and prevalent patients, respectively. The reduction was also significant by risk stratum (36.8% of patients in the high-very high risk strata at baseline versus 14.0% after ≥6-month, p < 0.05) and therapy group. The REVEAL components that significantly improved were WHO functional class (FC) (63.9% FC III at macitentan initiation and 23.6% after ≥6-month, p < 0.0001), 6-min walk test (mean change: 41.8 m, p < 0.01), brain natriuretic peptide (BNP) or N-terminal proBNP (NT-proBNP) (mean change of - 157.6 pg/mL and - 530.0 pg/mL, respectively, p < 0.05 both), and pulmonary vascular resistance (PVR) (mean change: - 3.4 WU, p < 0.01). Conclusions: In this study, treatment with macitentan improved the REVEAL risk strata and score in both incident and prevalent PAH patients, and in all patients regardless of the therapy strategy. Macitentan significantly improved some of REVEAL components including WHO FC, BNP/NT-proBNP, PVR, and 6-min walk test after at least 6-month follow-up

Pulmonary thromboendarterectomy in chronic thromboembolic pulmonary hypertension: the Spanish experience

Background: Chronic thromboembolic pulmonary hypertension (CTEPH) can be cured by pulmonary endarterectomy (PEA). It is considered the best and only curable treatment option for patients with accessible lesions evaluated as optimal candidates. We describe the experience of the two reference centers in Spain, in order to reinforce the need for referring CTEPH patients to a specialized center to be assessed by a Multidisciplinary Expert Team. Methods: We included a population of 338 patients who met the definition for CTEPH and underwent PEA between January 2007 and December 2019. The surgery was indicated in almost 60% of patients assessed. Demographic, anthropometric, hemodynamic and echocardiographic features are listed for PEA patients. Immediate and one-year postoperative outcomes as well as overall mortality were analyzed. Results: Mean age was 53.5±15.0 years, 53.8% were men; a total of 68.5% were in WHO functional class III-IV; and most of them were in a preoperative hemodynamic condition: mean pulmonary arterial pressure (mPAP) was 46.5±13.1 mmHg and mean pulmonary vascular resistance (PVR) was 764.5±392.8 dyn·s·cm-5. PEA surgery was performed with cardiopulmonary bypass (CBP) and circulatory arrest, with very few complications [including neurological, postoperative reperfusion edema, extracorporeal membrane oxygenation (ECMO) implant and cardiac failure] and optimal postoperative results, where exercise capacity increased and mPAP and PVR values decreased significantly. Presence of persistent pulmonary hypertension (PH) at the six-month right heart catheterization was evaluated. A 3.3% perioperative mortality was achieved. Overall, one-, three- and five-year survival rates were analyzed by Kaplan-Meier's method (94.8%, 93.3% and 90.5% respectively), as well as for residual PH patients. Mortality risk factors were assessed. Conclusions: Outstanding PEA results were seen in the immediate, one-year and long-term outcomes. The incidence of complications, including in-hospital mortality and long-term mortality were also below European rates

Total, Bioavailable, and Free Vitamin D Levels and Their Prognostic Value in Pulmonary Arterial Hypertension

Introduction: Epidemiological studies suggest a relationship between vitamin D deficiency and cardiovascular and respiratory diseases. However, whether total, bioavailable, and/or free vitamin D levels have a prognostic role in pulmonary arterial hypertension (PAH) is unknown. We aimed to determine total, bioavailable, and free 25-hydroxy-vitamin D (25(OH)vitD) plasma levels and their prognostic value in PAH patients. Methods: In total, 67 samples of plasma from Spanish patients with idiopathic, heritable, or drug-induced PAH were obtained from the Spanish PH Biobank and compared to a cohort of 100 healthy subjects. Clinical parameters were obtained from the Spanish Registry of PAH (REHAP). Results: Seventy percent of PAH patients had severe vitamin D deficiency (total 25(OH)vitD < 10 ng/mL) and secondary hyperparathyroidism. PAH patients with total 25(OH)vitD plasma above the median of this cohort (7.17 ng/mL) had better functional class and higher 6-min walking distance and TAPSE (tricuspid annular plane systolic excursion). The main outcome measure of survival was significantly increased in these patients (age-adjusted hazard ratio: 5.40 (95% confidence interval: 2.88 to 10.12)). Vitamin D-binding protein (DBP) and albumin plasma levels were downregulated in PAH. Bioavailable 25(OH)vitD was decreased in PAH patients compared to the control cohort. Lower levels of bioavailable 25(OH)vitD (<0.91 ng/mL) were associated with more advanced functional class, lower exercise capacity, and higher risk of mortality. Free 25(OH)vitD did not change in PAH; however, lower free 25(OH)vitD (<1.53 pg/mL) values were also associated with high risk of mortality. Conclusions: Vitamin D deficiency is highly prevalent in PAH, and low levels of total 25(OH)vitD were associated with poor prognosis

Oral anticoagulants (NOAC and VKA) in chronic thromboembolic pulmonary hypertension

EXPERT was an international, multicenter, prospective, uncontrolled, non-interventional cohort study in patients with pulmonary hypertension treated with riociguat. Patients were followed for 1-4 years, and the primary outcomes were adverse events (AEs) and serious AEs (SAEs), including embolic/thrombotic and hemorrhagic events. Here we report data on patients with chronic thromboembolic pulmonary hypertension (CTEPH) receiving a vitamin K antagonist (VKA; n = 683) or a non-vitamin K antagonist oral anticoagulant (NOAC; n = 198) at baseline. AEs and SAEs were reported in 438 patients (64.1%) and 257 patients (37.6%), respectively, in the VKA group, and in 135 patients (68.2%) and 74 patients (37.4%) in the NOAC group. Exposure-adjusted hemorrhagic event rates were similar in the two groups, while exposure-adjusted embolic and/or thrombotic event rates were higher in the NOAC group, although the numbers of events were small. Further studies are required to determine the long-term effects of anticoagulation strategies in CTEPH

Balloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension: a clinical consensus statement of the ESC working group on pulmonary circulation and right ventricular function.

The current treatment algorithm for chronic thromboembolic pulmonary hypertension (CTEPH) as depicted in the 2022 European Society of Cardiology (ESC)/European Respiratory Society (ERS) guidelines on the diagnosis and treatment of pulmonary hypertension (PH) includes a multimodal approach of combinations of pulmonary endarterectomy (PEA), balloon pulmonary angioplasty (BPA) and medical therapies to target major vessel pulmonary vascular lesions, and microvasculopathy. Today, BPA of >1700 patients has been reported in the literature from centers in Asia, the US, and also Europe; many more patients have been treated outside literature reports. As BPA becomes part of routine care of patients with CTEPH, benchmarks for safe and effective care delivery become increasingly important. In light of this development, the ESC Working Group on Pulmonary Circulation and Right Ventricular Function has decided to publish a document that helps standardize BPA to meet the need of uniformity in patient selection, procedural planning, technical approach, materials and devices, treatment goals, complications including their management, and patient follow-up, thus complementing the guidelines. Delphi methodology was utilized for statements that were not evidence based. First, an anatomical nomenclature and a description of vascular lesions are provided. Second, treatment goals and definitions of complete BPA are outlined. Third, definitions of complications are presented which may be the basis for a standardized reporting in studies involving BPA. The document is intended to serve as a companion to the official ESC/ERS guidelines

Clinical Heterogeneity of Pulmonary Arterial Hypertension Associated With Variants in TBX4

Background: The knowledge of hereditary predisposition has changed our understanding of Pulmonary Arterial Hypertension. Genetic testing has been widely extended and the application of Pulmonary Arterial Hypertension specific gene panels has allowed its inclusion in the diagnostic workup and increase the diagnostic ratio compared to the traditional sequencing techniques. This is particularly important in the differential diagnosis between Pulmonary Arterial Hypertension and Pulmonary Venoocclusive Disease. Methods: Since November 2011, genetic testing is offered to all patients with idiopathic, hereditable and associated forms of Pulmonary Arterial Hypertension or Pulmonary Venoocclusive Disease included in the Spanish Registry of Pulmonary Arterial Hypertension. Herein, we present the clinical phenotype and prognosis of all Pulmonary Arterial Hypertension patients with disease-associated variants in TBX4. Results: Out of 579 adults and 45 children, we found in eight patients from seven families, disease-causing associated variants in TBX4. All adult patients had a moderate-severe reduction in diffusion capacity. However, we observed a wide spectrum of clinical presentations, including Pulmonary Venoocclusive Disease suspicion, interstitial lung disease, pulmonary vascular abnormalities and congenital heart disease. Conclusions: Genetic testing is now essential for a correct diagnosis work-up in Pulmonary Arterial Hypertension. TBX4-associated Pulmonary Arterial Hypertension has marked clinical heterogeneity. In this regard, a genetic study is extremely useful to obtain an accurate diagnosis and provide appropriate management.This project was founded by Project "Bases Gene´tico Moleculares de la Medicina de Precisio´n en la Hipertensio´n Arterial Pulmonar". Funder: Instituto Carlos III. Ministerio de Economı´a y Competitividad. https://www.isciii.es/Paginas/Inicio.aspx Award number: PI 18/01233 Grant Recipient: P E-