Pulmonary hypertension associated with lung disease: new insights into pathomechanisms, diagnosis, and management

Noncoding RNAs in chronic obstructive pulmonary disease: From pathogenesis to therapeutic targets

Chronic obstructive pulmonary disease (COPD) is the most prevalent chronic respiratory disorder that is becoming the leading cause of morbidity and mortality on a global scale. There is an unmet need to investigate the underlying pathophysiological mechanisms and unlock novel therapeutic avenues for COPD. Recent research has shed light on the significant roles played by diverse noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), in orchestrating the development and progression of COPD. This review provides an overview of the regulatory roles of ncRNAs in COPD, elucidating their underlying mechanisms, and illuminating the potential prospects of RNA-based therapeutics in the management of COPD.

Pulmonary vascular disease in chronic lung diseases: cause or comorbidity?

PURPOSE OF REVIEW

To provide timely and relevant insights into the complex relationship between pulmonary vascular disease (PVD) and chronic lung disease (CLD), focusing on the causative and consequential dynamics between these conditions.

RECENT FINDINGS

There are shared pathogenic mechanisms between pulmonary arterial hypertension (PAH) and group 3 pulmonary hypertension, including altered expression of mediators and growth factors implicated in both conditions. Factors such as hypoxia, hypoxemia, and hypercapnia also contribute to pulmonary vascular remodelling and endothelial dysfunction. However, the role of hypoxia as the sole driver of pulmonary hypertension in CLD is being reconsidered, particularly in chronic obstructive pulmonary disease (COPD), with evidence suggesting a potential role for cigarette smoke products in initiating pulmonary vascular impairment. On the other hand, interstitial lung disease (ILD) encompasses a group of heterogeneous lung disorders characterized by inflammation and fibrosis of the interstitium, leading to impaired gas exchange and progressive respiratory decline, which could also play a role as a cause of pulmonary hypertension.

SUMMARY

Understanding the intricate interplay between the pulmonary vascular compartment and the parenchymal and airway compartments in respiratory disease is crucial for developing effective diagnostic and therapeutic strategies for patients with PVD and CLD, with implications for both clinical practice and research.

Expiratory Venous Volume and Arterial Tortuosity are Associated with Disease Severity and Mortality Risk in Patients with COPD: Results from COSYCONET

Purpose

The aim of this study was to evaluate the association between computed tomography (CT) quantitative pulmonary vessel morphology and lung function, disease severity, and mortality risk in patients with chronic obstructive pulmonary disease (COPD).

Patients and Methods

Participants of the prospective nationwide COSYCONET cohort study with paired inspiratory-expiratory CT were included. Fully automatic software, developed in-house, segmented arterial and venous pulmonary vessels and quantified volume and tortuosity on inspiratory and expiratory scans. The association between vessel volume normalised to lung volume and tortuosity versus lung function (forced expiratory volume in 1 sec [FEV1]), air trapping (residual volume to total lung capacity ratio [RV/TLC]), transfer factor for carbon monoxide (TLCO), disease severity in terms of Global Initiative for Chronic Obstructive Lung Disease (GOLD) group D, and mortality were analysed by linear, logistic or Cox proportional hazard regression.

Results

Complete data were available from 138 patients (39% female, mean age 65 years). FEV1, RV/TLC and TLCO, all as % predicted, were significantly (p < 0.05 each) associated with expiratory vessel characteristics, predominantly venous volume and arterial tortuosity. Associations with inspiratory vessel characteristics were absent or negligible. The patterns were similar for relationships between GOLD D and mortality with vessel characteristics. Expiratory venous volume was an independent predictor of mortality, in addition to FEV1.

Conclusion

By using automated software in patients with COPD, clinically relevant information on pulmonary vasculature can be extracted from expiratory CT scans (although not inspiratory scans); in particular, expiratory pulmonary venous volume predicted mortality.

Trial Registration

NCT01245933.

Treatment patterns and factors associated with adherence in pulmonary arterial hypertension

OBJECTIVE

Improving understanding of actual pulmonary hypertension (PH) treatment adherence patterns is crucial to properly treating these patients. We aimed to primarily assess adherence to treatments used for pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) specific therapies, identify potential factors related to it and secondly describe its treatment patterns.

METHODS

A 6-month observational cross-sectional study in a tertiary care hospital was conducted. Patients with PH-targeted therapy who picked it up in the ambulatory hospital pharmacy and who had been on treatment with the same drug for at least 1 year were included. Adherence was assessed as: 1) Proportion of days covered (PDC); and 2) Simplified Medication Adherence Questionnaire (SMAQ). PDC ≥80% was considered adherent. Statistical analyses were performed to evaluate the study outcomes. Logistic regressions were estimated to identify the association between baseline characteristics and factors associated with adherence. P < 0.05 indicated statistical significance.

RESULTS

A total of 63 patients with 127 different treatments were included, 71.4% were females with a mean age (SD) of 59 (15) years. PAH was the most common diagnosis (74.6%). Double therapy was used in 39.7% of patients, being the combination of Macitentan + Tadalafil and Ambrisentan + Tadalafil the most prescribed. Endothelin receptor antagonists were the most used treatment (40.2%). Adherence according to PDC was 93.7%, showing no great differences depending on the targeted drug used, and according to SMAQ 61.9%. The agreement degree of both methods was slight (65.1%; Kappa 0.12). Only female sex (OR: 0.23, 95% CI: 0.06-0.90; p = 0.035) was associated with worse adherence in the SMAQ method but not in the PDC. Adverse events were reported by a 55.6% of participants and the perception of effective treatment was high (95.2%).

CONCLUSIONS

Adherence to PH therapy differs depending on the assessment method; PDC showed greater adherence rate than SMAQ. According to SMAQ, female sex may have a negative impact on adherence in this cohort, but PDC revealed no factors influencing it. No notable differences in adherence between treatment types were found and generally patients felt the treatments were effective in controlling their disease.

Analysis of clinical characteristics, prognosis and influencing factors in patients with bronchiectasis-chronic obstructive pulmonary disease overlap syndrome: A prospective study for more than five years

Background

Considering the large population of bronchiectasis and chronic obstructive pulmonary disease (COPD) patients in China, we aimed to conduct a thorough analysis that investigates the clinical characteristics and prognosis of bronchiectasis-COPD overlap syndrome (BCOS). Further, we aimed to explore factors associated with acute exacerbation and death in BCOS, which may be of value in its early diagnosis and intervention.

Methods

We recruited inpatients with COPD from the second Xiangya Hospital of Central South University in China in August 2016, with follow-up until March 2022. Patients in the BCOS group had to meet the criteria for diagnosing bronchiectasis. We used self-completion questionnaires, clinical records, and self-reported data as primary data collection methods. We used Kaplan-Meier survival analyses and Cox proportional hazard models to assess the risk of severe acute exacerbation and death for BCOS during the follow-up period.

Results

A total of 875 patients were included and followed up. Patients in the BCOS group had more females, fewer smokers, lower discharge COPD assessment test (CAT) scores, lower forced vital capacity (FVC), a higher likelihood of co-occurring active tuberculosis, higher levels of eosinophils and inflammatory markers, and a higher rate of positive sputum cultures for Pseudomonas aeruginosa than patients in the COPD-only group. Patients in the acute exacerbation group (AE+) were found to have lower body mass index (BMI), more frequent acute exacerbations, higher modified Medical Research Council (mMRC) dyspnoea grade on admission, higher inflammatory markers, lower FVC, higher rates of using inhaled bronchodilators, and higher rates of both positive and Pseudomonas aeruginosa positive sputum cultures. Patients in the 'death' group were older, had a lower BMI, had spent longer time in the hospital, had higher mMRC dyspnoea grade and CAT scores upon admission and discharge, had higher levels of inflammatory markers, lower rates of using inhaled bronchodilators, were more likely to have a combination of pulmonary heart disease and obsolete pulmonary tuberculosis, as well as a higher rate of fungus-positive sputum cultures. Both erythrocyte sedimentation rate at baseline and Pseudomonas aeruginosa culture positivity were confirmed as independent predictors of severe acute exacerbation in multivariate analysis during the years of follow-up. Fungus culture positivity baseline blood urea nitrogen, baseline lymphocyte count, comorbidities with obsolete pulmonary tuberculosis and comorbidities with pulmonary heart disease were verified as independent predictors of death in multivariate analysis during the years of follow-up. Kaplan-Meier curves under survival analysis demonstrated no statistically significant difference in mortality between the COPD and the BCOS groups at the full one, two, and three years of follow-up.

Conclusions

Patients with BCOS present with reduced lung function, increased susceptibility to different complications, elevated blood eosinophils and inflammatory markers, and elevated rates of positive Pseudomonas aeruginosa cultures. These distinctive markers are linked to a greater risk of severe acute exacerbations and mortality.

A peripheral system disease-Pulmonary hypertension

Pulmonary hypertension (PH) is a cardiovascular disorder characterized by substantial morbidity and mortality rates. It is a chronic condition characterized by intricate pathogenesis and uncontrollable factors. We summarized the pathological effects of estrogen, genetics, neuroinflammation, intestinal microbiota, metabolic reorganization, and histone modification on PH. PH is not only a pulmonary vascular disease, but also a systemic disease. The findings emphasize that the onset of PH is not exclusively confined to the pulmonary vasculature, consequently necessitating treatment approaches that extend beyond targeting pulmonary blood vessels. Hence, the research on the pathological mechanism of PH is not limited to target organs such as pulmonary vessels, but also focuses on exploring other fields (such as estrogen, genetics, neuroinflammation, intestinal microbiota, metabolic reorganization, and histone modification).

Defining the role of exertional hypoxemia and pulmonary vasoconstriction on lung function decline, morbidity, and mortality in patients with chronic obstructive lung disease - the PROSA study: rationale and study design

BACKGROUND

Chronic obstructive lung disease (COPD) has diverse molecular pathomechanisms and clinical courses which, however, are not fully mirrored by current therapy. Intermittent hypoxemia is a driver of lung function decline and poor outcome, e.g., in patients with concomitant obstructive sleep apnea. Transient hypoxemia during physical exercise has been suggested to act in a similar manner. The PROSA study is designed to prospectively assess whether the clinical course of COPD patients with or without exertional desaturation differs, and to address potential pathophysiological mechanisms and biomarkers.

METHODS

148 COPD patients (GOLD stage 2-3, groups B or C) will undergo exercise testing with continuous pulse oximetry. They will be followed for 36 months by spirometry, echocardiography, endothelial function testing, and biomarker analyses. Exercise testing will be performed by comparing the 6-min walk test (6MWT), bicycle ergometry, and a 15-sec breath-hold test. Exertional desaturation will be defined as SpO2 < 90% or delta-SpO2 ≥ 4% during the 6MWT. The primary endpoint will be the rate of decline of FEV1(LLN) between COPD patients with and without exertional desaturation.

DISCUSSION

The PROSA Study is an investigator-initiated prospective study that was designed to prove or dismiss the hypothesis that COPD patients with exertional desaturation have a significantly more rapid rate of decline of lung function as compared to non-desaturators. A 20% difference in the primary endpoint was considered clinically significant; it can be detected with a power of 90%. If the primary endpoint will be met, exercise testing with continuous pulse oximetry can be used as a ubiquitously available, easy screening tool to prospectively assess the risk of rapid lung function decline in COPD patients at an early disease stage. This will allow to introduce personalized, risk-adapted therapy to improve COPD outcome in the long run. PROSA is exclusively funded by public funds provided by the European Research Council through an ERC Advanced Grant. Patient recruitment is ongoing; the PROSA results are expected to be available in 2028.

TRIAL REGISTRATION

The PROSA Study has been prospectively registered at clinicaltrials.gov (register no. NCT06265623, dated 09.02.2024).

Pulmonary vascular resistance predicts the mortality in patients with bronchiectasis-associated pulmonary hypertension

OBJECTIVE

Pulmonary hypertension is a severe complication of bronchiectasis, characterized by elevated pulmonary vascular resistance (PVR) and subsequent right heart failure. The association between PVR and mortality in bronchiectasis-associated pulmonary hypertension has not been investigated previously.

METHODS

In the present study, a retrospective analysis was conducted on 139 consecutive patients diagnosed with bronchiectasis-associated pulmonary hypertension based on right heart catheterization, enrolled between January 2010 and June 2023. Baseline clinical characteristics and hemodynamic assessment were analyzed. The survival time for each patient was calculated in months from the date of diagnosis until the date of death or, if the patient was still alive, until their last visit.

RESULTS

Patients with bronchiectasis-associated pulmonary hypertension exhibited estimated survival rates of 89.5, 70, and 52.9 at 1-year, 3-year, and 5-year intervals respectively, with a median survival time of 67 months. Multivariable Cox regression analysis revealed that increased age [(adjusted hazard ratio per year 1.042, 95% confidence interval (CI) 1.008-1.076, P = 0.015] and elevated PVR (adjusted HR per 1 Wood Units 1.115, 95% CI 1.015-1.224, P = 0.023) were associated with an increased risk of all-cause mortality. In contrast, higher BMI was associated with a decreased risk of all-cause death (adjusted hazard ratio per 1 kg/m2 0.915, 95% CI 0.856-0.979, P = 0.009). Receiver-operating characteristic analyses identified a cutoff value for PVR at 4 Wood Units as predictive for all-cause death within 3 years [area under the curve (AUC) = 0.624; specificity= 87.5%; sensitivity= 35.8%; P < 0.05]. Patients with a PVR greater than 4 Wood Units had a significantly higher risk of all-cause death compared with those with 4 Wood Units or less (adjusted hazard ratio 2.392; 95% CI 1.316-4.349; P = 0.019). Notably, there were no significant differences in age, sex, BMI, WHO functional class, 6-min walk distance, and NT-proBNP levels at baseline between patients categorized as having 4 Wood Units or less or greater than 4 Wood Units for PVR.

CONCLUSION

Based on these data, PVR could serve as a discriminative marker for distinguishing between nonsevere pulmonary hypertension (PVR ≤ 4 Wood Units) and severe pulmonary hypertension (PVR > 4 Wood Units). The utilization of a PVR cutoff value of 4.0 Wood Units provides enhanced prognostic capabilities for predicting mortality.

Severe pulmonary hypertension in pulmonary alveolar microlithiasis: A comprehensive literature review

This review focuses on Pulmonary Alveolar Microlithiasis (PAM), an autosomal recessive genetic disorder characterized by calcium crystal deposits (microliths) resulting from loss of function of the SLC34A2 gene. PAM is a rare disease with approximately 1100 reported cases globally. The historical context of its discovery and the genetic, epidemiological, and pathophysiological aspects are discussed. PAM falls under interstitial lung diseases and is associated with pulmonary hypertension (PH), primarily categorized as Group 3 PH. The clinical manifestations, diagnostic approaches, and challenging aspects of treatment are explored. A clinical case of PAM with severe pulmonary hypertension is presented, emphasizing the importance of comprehensive evaluation and the potential benefits of phosphodiesterase-5 inhibitors (PDE5i) therapy. Despite limited therapeutic options and challenging diagnosis, this review sheds light on recent developments and emerging treatments for PAM and associated pulmonary hypertension.

NGF increases Connexin-43 expression and function in pulmonary arterial smooth muscle cells to induce pulmonary artery hyperreactivity

AIMS

Pulmonary hypertension (PH) is characterised by an increase in pulmonary arterial pressure, ultimately leading to right ventricular failure and death. We have previously shown that nerve growth factor (NGF) plays a critical role in PH. Our objectives here were to determine whether NGF controls Connexin-43 (Cx43) expression and function in the pulmonary arterial smooth muscle, and whether this mechanism contributes to NGF-induced pulmonary artery hyperreactivity.

METHODS AND RESULTS

NGF activates its TrkA receptor to increase Cx43 expression, phosphorylation, and localization at the plasma membrane in human pulmonary arterial smooth muscle cells, thus leading to enhanced activity of Cx43-dependent GAP junctions as shown by Lucifer Yellow dye assay transfer and fluorescence recovery after photobleaching -FRAP- experiments. Using both in vitro pharmacological and in vivo SiRNA approaches, we demonstrate that NGF-dependent increase in Cx43 expression and activity in the rat pulmonary circulation causes pulmonary artery hyperreactivity. We also show that, in a rat model of PH induced by chronic hypoxia, in vivo blockade of NGF or of its TrkA receptor significantly reduces Cx43 increased pulmonary arterial expression induced by chronic hypoxia and displays preventive effects on pulmonary arterial pressure increase and right heart hypertrophy.

CONCLUSIONS

Modulation of Cx43 by NGF in pulmonary arterial smooth muscle cells contributes to NGF-induced alterations of pulmonary artery reactivity. Since NGF and its TrkA receptor play a role in vivo in Cx43 increased expression in PH induced by chronic hypoxia, these NGF/Cx43-dependent mechanisms may therefore play a significant role in human PH pathophysiology.

Sarcoidosis-Associated Pulmonary Hypertension

Sarcoidosis-associated pulmonary hypertension (SAPH) is a very severe complication of the disease, largely impacting its morbidity and being one of its strongest predictors of mortality. With the recent modifications of the hemodynamic definition of pulmonary hypertension (mean arterial pulmonary pressure >20 instead of <25 mmHg,) its prevalence is presently not precisely known, but it affects from 3 to 20% of sarcoid patients; mostly, although not exclusively, those with an advanced, fibrotic pulmonary disease. Its gold-standard diagnostic tool remains right heart catheterization (RHC). The decision to perform it relies on an expert decision after a non-invasive work-up, in which echocardiography remains the screening tool of choice. The mechanisms underlying SAPH, very often entangled, are crucial to define, as appropriate and personalized therapeutic strategies will aim at targeting the most significant ones. There are no recommendations so far as to the indications and modalities of the medical treatment of SAPH, which is based upon the opinion of a multidisciplinary team of sarcoidosis, pulmonary hypertension and sometimes lung transplant experts.

Survival and response to pulmonary vasodilator therapies in patients with chronic obstructive pulmonary disease and pulmonary vascular phenotype

BACKGROUND

The aim of the study was to describe and investigate the effect of pulmonary arterial hypertension (PAH) therapies in a cohort of patients with severe precapillary pulmonary hypertension (PH) associated with chronic obstructive pulmonary disease (COPD; PH-COPD), and to assess factors predictive of treatment response and mortality.

MATERIAL AND METHODS

We retrospectively included patients with severe incident PH-COPD who received PAH therapy and underwent RHC at diagnosis and on treatment.

RESULTS

From 2015 to 2022, 35 severe PH-COPD patients, with clinical features of pulmonary vascular phenotype, were included. Seventeen (48.5%) patients were treated with combined PAH therapy. PAH therapy led to a significant improvement in hemodynamics (PVR -3.5 Wood Units (-39.3%); p < 0.0001), and in the simplified four-strata risk-assessment score, which improved by at least one category in 21 (60%) patients. This effect was more pronounced in patients on dual therapy. Kaplan-Meier estimated survival rates at 1, 3 and 5 years were 94%, 65% and 42% respectively. Univariate analysis showed a significant reduction in survival in patients with a higher simplified risk score at follow-up (Hazard ratio (HR) 2.88 [1.16-7.15]; p = 0.02). Hypoxemia <50 mmHg was correlated to mortality in multivariate analysis (HR 4.33 [1.08-17.42]; p = 0.04).

CONCLUSIONS

Our study confirms the poor prognosis of patients with COPD and a pulmonary vascular phenotype and the potential interest of combined PAH therapy in this population, with good tolerability and greater clinical and hemodynamic improvement than monotherapy. Using the simplified risk score during follow-up could be of interest in this population.

Cardiovascular disease and risk in COPD: a state of the art review

INTRODUCTION

Chronic Obstructive Pulmonary Disease (COPD) and cardiovascular diseases (CVD) commonly co-exist. Outcomes of people living with both conditions are poor in terms of symptom burden, receiving evidence-based treatment and mortality. Increased understanding of the underlying mechanisms may help to identify treatments to relieve this disease burden. This narrative review covers the overlap of COPD and CVD with a focus on clinical presentation, mechanisms, and interventions. Literature up to December 2023 are cited.

AREAS COVERED

1. What is COPD 2. The co-existence of COPD and cardiovascular disease 3. Mechanisms of cardiovascular disease in COPD. 4. Populations with COPD are at risk of CVD 5. Complexity in the co-diagnosis of COPD in those with cardiovascular disease. 6. Therapy for COPD and implications for cardiovascular events and risk. 7. Cardiovascular risk and exacerbations of COPD. 8. Pro-active identification and management of CV risk in COPD.

EXPERT OPINION

The prospective identification of co-morbid COPD in CVD patients and of CVD and CV risk in people with COPD is crucial for optimizing clinical outcomes. This includes the identification of novel treatment targets and the design of clinical trials specifically designed to reduce the cardiovascular burden and mortality associated with COPD. Databases searched: Pubmed, 2006-2023.

Forsythoside B Mitigates Monocrotaline-Induced Pulmonary Arterial Hypertension via Blocking the NF-κB Signaling Pathway to Attenuate Vascular Remodeling

Purpose

Pulmonary arterial hypertension (PAH) is a devastating disease with little effective treatment. The proliferation of pulmonary artery smooth muscle cells (PASMCs) induced by the nuclear factor-κB (NF-κB) signaling activation plays a pivotal role in the pathogenesis of PAH. Forsythoside B (FTS•B) possesses inhibitory effect on NF-κB signaling pathway. The present study aims to explore the effects and mechanisms of FTS•B in PAH.

Methods

Sprague-Dawley rats received monocrotaline (MCT) intraperitoneal injection to establish PAH model, and FTS•B was co-treated after MCT injection. Right ventricular hypertrophy and pulmonary artery pressure were measured by echocardiography and right heart catheterization, respectively. Histological alterations were detected by H&E staining and immunohistochemistry. FTS•B's role in PASMC proliferation and migration were evaluated by CCK-8 and wound healing assay. To investigate the underlying mechanisms, Western blotting, immunofluorescence staining and ELISA were conducted. The NF-κB activator PMA was used to investigate the role of NF-κB in FTS•B's protective effects against PAH.

Results

FTS•B markedly alleviated MCT-induced vascular remodeling and pulmonary artery pressure, and improved right ventricular hypertrophy and survival. FTS•B also reversed PDGF-BB-induced PASMC proliferation and migration, decreased PCNA and CyclinD1 expression in vitro. The elevated levels of IL-1β and IL-6 caused by MCT were decreased by FTS•B. Mechanistically, MCT-triggered phosphorylation of p65, IκBα, IKKα and IKKβ was blunted by FTS•B. FTS•B also reversed MCT-induced nuclear translocation of p65. However, all these protective effects were blocked by PMA-mediated NF-κB activation.

Conclusion

FTS•B effectively attenuates PAH by suppressing the NF-κB signaling pathway to attenuate vascular remodeling. FTS•B might be a promising drug candidate with clinical translational potential for the treatment of PAH.

Pulmonary hypertension in chronic obstructive pulmonary disease: current understanding, knowledge gaps and future directions

PURPOSE OF REVIEW

Despite the advent of effective and mechanistically diverse treatments for pulmonary arterial hypertension (PAH) and their positive impacts on the functional capacities and outcomes for PAH patients, the much larger population of patients with pulmonary hypertension (PH) in chronic lung diseases like chronic obstructive pulmonary disease (PH-COPD) remain without effective therapies.

RECENT FINDINGS

In this review, we will highlight advances in the understanding of PH-COPD pathobiology, the clinical impact comorbid PH has on COPD outcomes, and detail the spectrum of disease and clinical phenotypes that encompass the heterogenous disease manifestations of PH-COPD. Finally, we will examine recent studies exploring the effects of potential treatments for PH-COPD and highlight sub-populations and treatment options that warrant further study.

SUMMARY

As the PAH population-base ages and comorbid diseases become more frequently diagnosed in PAH patients, the need to clearly delineate subpopulations for clinical applications of PH therapies and research becomes even more urgent. Through an improved understanding of the clinical phenotypes of PH-COPD and the overlap with certain subpopulations of PAH, a framework for future research and potential for therapeutic impact is highlighted.

Treatment of pulmonary arterial hypertension: recent progress and a look to the future

Pulmonary arterial hypertension (PAH) is a severe but treatable form of pre-capillary pulmonary hypertension caused by pulmonary vascular remodelling. As a result of basic science discoveries, randomised controlled trials, studies of real-world data, and the development of clinical practice guidelines, considerable progress has been made in the treatment options and outcomes for patients with PAH, underscoring the importance of seamless translation of information from bench to bedside and, ultimately, to patients. However, PAH still carries a high mortality rate, which emphasises the urgent need for transformative innovations in the field. In this Series paper, written by a group of clinicians, researchers, and a patient with PAH, we review therapeutic approaches and treatment options for PAH. We summarise current knowledge of the cellular and molecular mechanisms of PAH, with an emphasis on emerging treatable pathways and optimisation of current management strategies. In considering future directions for the field, our ambition is to identify therapies with the potential to stall or reverse pulmonary vascular remodelling. We highlight novel therapeutic approaches, the important role of patients as partners in research, and innovative approaches to PAH clinical trials.