Relevant issues in the pathology and pathobiology of pulmonary hypertension

xCT/Slc7a11 promotes pulmonary arterial hypertension by disrupting AMPKα suppression of mTOR activation

While mTOR plays a key role in the development of pulmonary arterial hypertension (PAH), its suppressor, AMPKα, acts as an inhibitor. Although mTOR-driven transcriptional upregulation of the plasma membrane exchanger and amino acid transporter xCT, encoded by the Slc7a11 gene, is critical for cell proliferation and tumorigenesis, the involvement of xCT in PAH remains unexplored. In this study, we found that xCT expression was elevated in hypoxia-treated human pulmonary arterial endothelial cells (HPAECs) and the lungs of hypoxia-exposed mice and Sugen5416/hypoxia (SuHx)-induced PAH mice. Knockout of xCT prevented the development of PAH and right heart failure in SuHx-conditioned mice. The xCT inhibitor sulfasalazine prevented and reversed SuHx-induced PAH in mice. Deleting and inhibiting xCT activated AMPKα and inactivated mTOR in mouse lungs with PAH and in HPAECs. Sulfasalazine suppressed mTOR through activation of AMPKα in HPAECs. The mTOR inhibitor rapamycin reduced xCT expression, activated AMPKα, and suppressed mTOR in HPAECs. These findings suggest that xCT promotes the development of PAH, likely through suppression of AMPKα and activation of mTOR. Blockage of xCT and mTOR or activation of AMPKα by existing drugs such as sulfasalazine, sirolimus, and metformin may offer readily therapeutic strategies for PAH.

Intravenous mesenchymal stem cell transplantation mitigates pulmonary vascular remodeling but poses dose related risks in a pulmonary veno-occlusive disease model

BACKGROUND

Pulmonary veno-occlusive disease (PVOD) is a rare subtype of disease that causes pulmonary hypertension with vascular involvement of postcapillary structures of pulmonary vasculature. The disease has a poor prognosis with no effective therapy. The study aimed to determine whether adipose-derived mesenchymal stem cells (ASCs) alleviate pulmonary hypertension and right ventricular hypertrophy in a rat model of PVOD.

METHODS

Allogeneic ASCs were intravenously administered to a rat model of PVOD induced by mitomycin C. Then, muscularization in pulmonary microvessels, right ventricular systolic pressure (RVSP), and right ventricular hypertrophy were assessed using immunohistochemistry, right heart catheterization, heart weight, and hematoxylin-eosin (HE) staining. Body weight over time and survival rates were assessed.

RESULTS

ASC transplantation substantially contributed to the reduction of pulmonary microvascular muscularization in the PVOD rat model but not to the decrease in RVSP. Furthermore, it led to the attenuation of right ventricular hypertrophy and a considerable decrease in wall thickness. However, repeated ASC administration increased the mortality rate in the PVOD rat models.

CONCLUSIONS

To the best of our knowledge, this is the first study to analyze the effects of ASC transplantation in a rat model of PVOD. While intravenous ASC transplantation exerts beneficial effects on the lungs and right ventricle, adverse events may occur depending on the administration method. Therefore, intravenous ASC transplantation should be performed with caution.

Treg Cells Attenuate Pulmonary Venous Remodeling in PH-LHD via NLRC3 Signaling

BACKGROUND

Pulmonary venous remodeling is a key pathological feature of pulmonary hypertension associated with left heart disease (PH-LHD). This study aims to investigate the role of regulatory T (Treg) cells in this process.

METHODS

We used mouse models with transverse aortic constriction and cell depletion of Foxp3-DTR/tdTomato mice to examine Treg cells' function around pulmonary veins in PH-LHD in vivo. To confirm the effect of Nlrc3-/- Treg cells on PH-LHD, we utilized 3 mouse models: Nlrc3 knockout mice, athymic mice, and endothelial cell lineage tracing Cdh5CreERT2+/--mT/mG+/- mice. The interaction proteins and signaling pathways of Treg cells during endothelial-to-mesenchymal transition were elucidated by protein docking prediction, coimmunoprecipitation and cocultivation of Treg cells with venous endothelial cells.

RESULTS

Treg cells were abundant around pulmonary veins of transverse aortic constriction-induced PH-LHD and were essential for promoting inflammation resolution and inhibiting pulmonary venous remodeling. Nlrc3 expression was reduced in mice and patients with PH-LHD. NLRC3 (nucleotide-oligomerization domain-like receptor family CARD domain containing 3) deficiency inhibited Treg cell proliferation and impaired their immunosuppressive and endothelial-to-mesenchymal transition-protective effects. Mechanistically, NLRC3 interacted with TRAM (TRIF-related adaptor molecule) and regulated interferon regulatory factor 3 (IRF3)/NF-κB (nuclear factor-κB) p65 signaling in cluster differentiation 4+ (CD4+) T cells. NLRC3-deficient Treg cells promoted interleukin (IL)-18 expression through IRF3/NF-κB p65 signaling, and thus IL-18 secretion activated endothelial receptor tyrosine kinase (RTK) signaling, favoring endothelial-to-mesenchymal transition progression in pulmonary veins and PH-LHD progress. This process was reversible with IL-18 binding protein in vivo.

CONCLUSIONS

NLRC3 is crucial for Treg cells to prevent pulmonary venous remodeling in PH-LHD, primarily by modulating IL-18 secretion, which inhibits endothelial-to-mesenchymal transition and thereby improves disease progression and prognosis.

Historical milestones and future horizons: exploring the diagnosis and treatment evolution of the pulmonary arterial hypertension in adults

INTRODUCTION

Pulmonary hypertension is a life-threatening condition characterized by elevated mean pulmonary arterial pressure and vascular resistance. Significant advances in diagnosis and treatment have been achieved over the 20th and 21st centuries, yet challenges remain in improving long-term outcomes.

AREAS COVERED

This review discusses the historical milestones in understanding and pharmacotherapy of the pulmonary arterial hypertension (PAH). A comprehensive literature search was conducted to explore the earliest reports of each approved medication for pulmonary hypertension, along with historical papers detailing the pathophysiological and diagnostic development. Additionally, the search aimed to identify novel therapeutic strategies, including repositioned drugs and emerging targets.

EXPERT OPINION

While current therapies, such as prostacyclin analogs and PDE5 inhibitors, improve functional capacity and hemodynamics, they face limitations, including costs, administration, and a predominantly vasodilatory approach. Additionally, the limitations of current clinical trial designs for rare diseases like pulmonary arterial hypertension hinder the evaluation of potentially effective drugs. These challenges underscore the urgent need for translational research to optimize trial methodologies, accelerating the development of new therapies. Innovative approaches, such as drug repositioning and the exploration of novel molecular targets, are critical to overcoming these barriers and ensuring timely, effective, and affordable treatment options for patients with PAH.

Targeting lung heme iron by aerosol hemopexin adminstration in sickle cell disease pulmonary hypertension

Lung tissue from human patients and murine models of sickle cell disease pulmonary hypertension (SCD-PH) show perivascular regions with excessive iron accumulation. The iron accumulation arises from chronic hemolysis and extravasation of hemoglobin (Hb) into the lung adventitial spaces, where it is linked to nitric oxide depletion, oxidative stress, inflammation, and tissue hypoxia, which collectively drive SCD-PH. Here, we tested the hypothesis that intrapulmonary delivery of hemopexin (Hpx) to the deep lung is effective at scavenging heme-iron and attenuating the progression of SCD-PH. Herein, we evaluated in a murine model of hemolysis driven SCD-PH, if intrapulmonary Hpx administration bi-weekly for 10 weeks improves lung iron deposition, exercise tolerance, cardiovascular function, and multi-omic indices associated with SCD-PH. Data shows Hpx delivered with a micro-sprayer deposits Hpx in the alveolar regions. Hpx extravasates into the perivascular compartments but does not diffuse into the circulation. Histological examination shows Hpx therapy decreased lung iron deposition, 4-HNE, and HO-1 expression. This was associated with improved exercise tolerance, cardiopulmonary function, and multi-omic profile of whole lung and RV tissue. Our data provides proof of concept that treating lung heme-iron by direct administration of Hpx to the lung attenuates the progression of PH associated with SCD.

Genome-wide characterization of circular RNAs in three rat models of pulmonary hypertension reveals distinct pathological patterns

BACKGROUND

Pulmonary hypertension (PH) is a devastating disease marked by elevated pulmonary artery pressure, resulting in right ventricular (RV) failure and mortality. Despite the identification of several dysregulated genes in PH, the involvement of circular RNAs (circRNAs), a subset of long noncoding RNAs, remains largely unknown.

METHODS

In this study, high-throughput RNA sequencing was performed to analyze the genome-wide expression patterns of circRNAs in pulmonary arteries from three models of PH rats induced by hypoxia (Hyp), hypoxia/Sugen5416 (HySu), and monocrotaline (MCT). Differentially expressed circRNAs (DEcircRNAs) were identified, and a weighted gene coexpression network was constructed to explore circRNA networks associated with PH pathogenesis. A circRNA-miRNA-mRNA regulatory network was built, and the functional significance of targeted mRNAs was evaluated. Single-cell RNA sequencing provided insights into the distribution of cell type-specific circRNAs across PH progression.

RESULTS

Our analysis revealed 45 circRNAs exhibiting significant changes across all three PH rat models, with their host genes participating in the calcium signaling and muscle contraction. We identified 372 PH-related circRNA-miRNA-mRNA interactions, shedding light on the regulatory networks during PH development. Furthermore, we uncovered 186, 195 and 311 Hyp-, Hysu- and MCT-specific circRNAs, respectively. These circRNAs were enriched in distinct biological processes, emphasizing their unique regulatory roles. Single-cell spatial distribution analysis of these circRNAs in the pulmonary arteries of PH patients revealed that Hyp-specific circRNA predominantly appeared in the pulmonary vascular structural cells, while HySu- and MCT-specific circRNAs exhibited broader distribution, including significant enrichment in immune-related cells.

CONCLUSION

Our study presents the first comprehensive view of circRNA regulatory networks in the pulmonary arteries of three PH rat models. We provide insights into PH-associated circRNAs, particularly their involvement in calcium signaling and muscle contraction.

1,8-Cineole reduces pulmonary vascular remodelling in pulmonary arterial hypertension by restoring intercellular communication and inhibiting angiogenesis

BACKGROUND

Pulmonary Arterial Hypertension (PAH) is characterized by pulmonary vascular remodelling, often associated with disruption of BMPR2/Smad1/5 and BMPR2/PPAR-γ signalling pathways that ultimately lead to right ventricle failure. Disruption of intercellular junctions and communication and a pro-angiogenic environment are also characteristic features of PAH. Although, current therapies improve pulmonary vascular tone, they fail to tackle other key pathological features that could prevent disease progression. In this scenario, aromatic plants emerge as promising sources of bioactive compounds, with 1,8-cineole standing out due to its hypotensive properties and cardioprotective effect in PAH.

PURPOSE

The present study aims to explore for the first time the effect of 1,8-cineole in pulmonary vascular remodelling associated with PAH.

METHODS

Resorting to the monocrotaline (MCT)-induced PAH animal model, the effect of 1,8-cineole on vascular remodelling including interstitial collagen accumulation, smooth muscle cell proliferation and protein levels of BMPR2 pathway-related proteins, was assessed by microscopy and western blot (WB) analysis. The integrity of gap junctions, pulmonary surfactant, mitochondrial structure and endothelial cell barrier were evaluated by transmission electron microscopy, confocal microscopy and WB analysis. Furthermore, the effect of 1,8-cineole on angiogenesis was determined on pulmonary artery endothelial cells (PAEC) submitted to hypoxia using the scratch wound and Matrigel angiogenesis assays, and the number of sprouts on isolated healthy and diseased pulmonary artery rings, treated with the compound, enabled the validation of these effects.

RESULTS

1,8-Cineole mitigated PAH-associated derailment of both BMPR2/Smad1/5 and BMPR2/PPAR-γ pathways and concomitantly reduced interstitial fibrosis and the arterial medial layer thickness in pulmonary arteries. The compound restored gap junction, lung surfactant and mitochondrial integrity and preserved endothelial barrier integrity. Furthermore, 1,8-cineole exerted an anti-angiogenic effect, by impairing the formation of vessel-like structures in PAEC and sprouting formation in isolated pulmonary arteries.

CONCLUSION

The present study brings new insights about the mechanisms whereby 1,8-cineole impacts pulmonary vascular remodelling and demonstrates the potential of 1,8-cineole as a therapeutic strategy to hamper PAH progression.

Unraveling the pathogenesis of viral-induced pulmonary arterial hypertension: Possible new therapeutic avenues with mesenchymal stromal cells and their derivatives

Pulmonary hypertension (PH) is a severe condition characterized by elevated pressure in the pulmonary artery, where metabolic and mitochondrial dysfunction may contribute to its progression. Within the PH spectrum, pulmonary arterial hypertension (PAH) stands out with its primary pulmonary vasculopathy. PAH's prevalence varies from 0.4 to 1.4 per 100,000 individuals and is associated with diverse conditions, including viral infections such as HIV. Notably, recent observations highlight an increased occurrence of PAH among COVID-19 patients, even in the absence of pre-existing cardiopulmonary disorders. While current treatments offer partial relief, there's a pressing need for innovative therapeutic strategies, among which mesenchymal stromal cells (MSCs) and their derivatives hold promise. This review critically evaluates recent investigations into viral-induced PAH, encompassing pathogens like human immunodeficiency virus, herpesvirus, Cytomegalovirus, Hepatitis B and C viruses, SARS-CoV-2, and Human endogenous retrovirus K (HERKV), with a specific emphasis on mitochondrial dysfunction. Furthermore, we explore the underlying rationale driving novel therapeutic modalities, including MSCs, extracellular vesicles, and mitochondrial interventions, within the framework of PAH management.

A Narrative Review of Key Risk Factors for Severe Illness Following SARS-CoV-2, Influenza Virus, and Respiratory Syncytial Virus Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza, and respiratory syncytial virus (RSV) are highly infectious respiratory viruses that affect people of all ages and are typically associated with mild symptoms and few complications in immunocompetent individuals. However, the risk of severe outcomes (e.g., hospitalization and death) following infection with these respiratory viruses is higher in certain populations, including older adults and individuals of certain race/ethnic and sociodemographic groups. Additionally, immunocompromising conditions and pre-existing comorbidities, including underlying cardiovascular (e.g., congestive heart failure) and respiratory diseases (e.g., chronic obstructive pulmonary disease), diabetes, chronic kidney disease, and obesity, are key factors that predispose individuals to SARS-CoV-2-, influenza-, and RSV-related severe outcomes. Increased risk for severe outcomes associated with advancing age and comorbidities is compounded by residence in long-term care facilities due to the enhanced spread of respiratory infections in congregate living environments. In this narrative review, risk factors associated with severe outcomes following infection with SARS-CoV-2, influenza, and RSV in adult populations are explored. Additionally, distinct clinical outcomes based on underlying comorbidities following infection are discussed in the context of high-risk populations. Factors unique to each virus that underpin distinct risk profiles are described and suggest the potential for tailored surveillance and healthcare approaches to target and ultimately mitigate SARS-CoV-2-, influenza-, and RSV-associated disease burden in vulnerable populations. Mutual risk factors for severe outcomes are also highlighted; these similarities indicate that cohesive risk reduction strategies may also be feasible, particularly since vaccines are available for each of these respiratory viruses. Ultimately, a more thorough understanding of the risk factors that predispose individuals to develop SARS-CoV-2-, influenza-, and RSV-related severe outcomes may improve risk reduction strategies, inform healthcare policy, and contribute to the expansion and refinement of existing surveillance approaches to ultimately mitigate disease burden in vulnerable populations.

Development and validation of a mortality predictive model for ICU patients with primary pulmonary hypertension

There is a lack of an effective prognostic model for predicting outcomes in patients with primary pulmonary hypertension (PPH). A retrospective analysis was conducted on PPH patients from MIMIC and eICU databases. A predictive model was developed to assess mortality risk. The Consistency Index (C-index) and Receiver Operating Characteristic (ROC) curve were utilized to assess the overall performance of the model and its discriminatory capacity. The model's calibration and clinical applicability were assessed through calibration curve and decision curve analysis (DCA). The nomogram was employed for visual representation of the model. The study included 420 patients, 260 in the development group, 104 in the internal validation group and 56 in the external validation group. The predictive model's risk factors included age, respiratory rate, red blood cell distribution width, glucose, and SAPS II. The model demonstrated C-indexes of 0.736 and 0.696 in the development and internal validation groups, respectively. The ROC curves for the development, internal validation and external validation groups demonstrated robust discriminatory capabilities. The calibration curves indicated a slope close to 1, suggesting good calibration of the model. Additionally, DCA analysis revealed the model offered significant clinical benefits across a wide range of thresholds. The model showed good discrimination ability, accuracy and clinical application value in predicting the prognosis of patients with PPH.

LncRNA MYOSLID contributes to PH via targeting BMPR2 signaling in pulmonary artery smooth muscle cell

BACKGROUND/OBJECTIVE

The pathogenesis and vascular remodeling during pulmonary hypertension (PH) have been associated with dysregulation of bone morphogenetic protein receptor type 2 (BMPR2) and transforming growth factor-β (TGF-β) signaling in pulmonary artery smooth muscle cells (PASMCs). Evidence suggests that the human-specific lncRNA MYOSLID is a transcriptional target of the TGF-β/SMAD pathway. In this study, we investigated the involvement of MYOSLID in the pathogenesis of PH.

METHODS

Lung tissues from PH patients and rat PH models were analyzed to assess clinical relevance. RNA-Seq was performed to identify target genes. Pulmonary artery smooth muscle cells (PASMCs) were used to evaluate function and underlying mechanisms.

RESULTS

RNA-Seq analysis of PASMCs stimulated by TGF-β1 revealed significantly dysregulated lncRNAs. MYOSLID expression was markedly elevated in lung tissues from PH patients and in PASMCs stimulated with TGF-β1. Mechanistically, loss of MYOSLID inhibited the TGF-β pathway by reducing SMAD2/3 PHosphorylation and activated the BMPR2 pathway by enhancing SMAD1/5/9 phosphorylation and increasing ID genes expression in PASMCs. DAZAP2, a target gene of MYOSLID, functions as an inhibitor of BMPR2 signaling. Moreover, DAZAP2 expression was significantly elevated in lung tissues from PH patients and rat PH models. Functionally, knockdown of MYOSLID and DAZAP2 reduced proliferation, migration, and apoptosis resistance in PASMCs.

CONCLUSION

The activation of the MYOSLID-DAZAP2-BMPR2 axis contributes to pulmonary vascular remodeling, and targeting MYOSLID and DAZAP2 may represent novel therapeutic strategies for PH treatment.

A Network Meta-Analysis of Vasodilator Therapies in Pulmonary Hypertension Patients Undergoing Mitral Valve Replacement Surgery: Insights for Optimizing Hemodynamics

BACKGROUND AND OBJECTIVE

Pulmonary hypertension (PH) is a progressive hemodynamic condition associated with significant morbidity and mortality, especially in patients undergoing cardiac surgery. Therefore, the objective of this network meta-analysis (NMA) is to compare the efficacy of various pulmonary vasodilators in perioperative control of PH among patients undergoing mitral valve replacement surgery (MVRS), aiming to address the existing knowledge gap and improve perioperative outcomes.

METHODS

Electronic databases including PubMed, Cochrane Central Registry of Controlled Trials, Scopus, Embase, and Web of Science (WOS) from inception to 17 September 2024. Only randomized controlled trials (RCTs) evaluating vasodilators in PH patients undergoing MVRS were included. We used netmeta package in RStudio to analyze the outcome data with their corresponding mean difference (MD) and confidence intervals (CI).

RESULTS

Seventeen RCTs including 862 patients were analyzed. Prostacyclin, nitric oxide (NO), and sodium nitroprusside (SN) significantly reduced mean pulmonary arterial pressure with effect sizes [MD, 95% confidence interval (CI)] of (11.77, - 18.78; - 4.76; - 8.3, - 15.9; - 0.6; - 11.02, - 20.1; - 3.8, respectively). While no treatment showed significant efficacy on pulmonary capillary wedge pressure, systolic pulmonary arterial pressure, or heart rate, nitroglycerin, NO, and prostacyclin, showed significant increases in cardiac index with effect sizes (MD, 95% CI) of (1, 0.3; 1.7; 1.2 0.8; 1.6; 1.2 0.8; 1.6, respectively). Additionally, NO, prostacyclin, SN, and nitroglycerin demonstrated significant reductions in systemic vascular resistance (SVR), with effect sizes of. (- 0.54, - 0.82; - 0.26, - 0.37, - 0.65; - 0.09; - 0.47, - 0.77; - 0.16; - 0.14, - 0.24; - 0.03, respectively).

CONCLUSIONS

This NMA highlights prostacyclin, nitroglycerin, NO, and SN as consistently effective in improving hemodynamics for patients with PH undergoing MVRS, and provides valuable insights for surgeons to choose the suitable vasodilator for these surgeries. However, limitations and the need for further RCTs are acknowledged.

Proteomic Signatures of Right Ventricular Outcomes in Pulmonary Arterial Hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is a disease of progressive right ventricular (RV) failure with high morbidity and mortality. Our goal is to investigate proteomic features and pathways associated with RV-focused outcomes including mortality, RV dilation, and NT-proBNP (N-terminal pro-B-type natriuretic peptide) in PAH.

METHODS

Participants in a single-institution cohort with 3 years of follow-up underwent proteomic profiling of their plasma using 7288 aptamers (targeting 6467 unique human proteins). Partial least squares discriminant analysis was performed to assess global protein variation associated with mortality, RV dilation, and NT-proBNP levels. Differentially abundant proteins and enriched pathways associated with outcomes were identified following baseline adjustments. RV vulnerability models estimated associations for individuals with similar afterload following adjustment for pulmonary vascular resistance.

RESULTS

A total of 117 participants with PAH were included. Partial least squares discriminant analysis of the proteome showed clear separation between survivors and nonsurvivors, participants with dilated versus nondilated RVs, and across NT-proBNP levels. Proteins and pathways involving the ECM (extracellular matrix) were upregulated in participants who died during follow-up, those with severe RV dilation, and those with higher levels of NT-proBNP. Pulmonary vascular resistance adjustment reinforced the importance of ECM proteins in the association with RV vulnerability, independent of afterload. These findings were confirmed in independent PAH cohorts with available plasma proteomics and RV tissue gene and protein expression.

CONCLUSIONS

Distinct plasma proteomic profiles are associated with mortality, RV dilation, and NT-proBNP in PAH. Proteins and pathways governing tissue remodeling are strongly associated with poor outcomes, may mediate RV vulnerability to right heart failure, and represent promising candidates as biomarkers and potential therapeutic targets.

Neutrophil-to-lymphocyte ratio predicts poor prognosis in patients with chronic kidney disease-related pulmonary hypertension: A retrospective study

Inflammation plays a crucial role in chronic kidney disease (CKD) and pulmonary hypertension (PH). Considering that the neutrophil-to-lymphocyte ratio (NLR) has recently emerged as a powerful predictor of adverse outcomes in many chronic diseases, we aimed to investigate the association between NLR and all-cause mortality in patients with CKD-related PH. A total of 176 hospitalized patients with predialysis CKD-related PH were recruited retrospectively from January 2012 to June 2020 by reviewing electronic medical records. The NLR and clinical characteristics of the patients were included in the current analysis. The Kaplan-Meier method and univariate and multivariate Cox regression analyses were performed to identify the association between NLR and the incidence of all-cause mortality. Baseline NLR values were associated with hemoglobin, estimated glomerular filtration rate and C-reactive protein. During a median follow-up period of 32.5 (11.3-53.0) months, 23 patients died. Regardless of whether the NLR acted as a continuous variable with a hazard ratio of 1.408 (95% confidence interval: 1.124-1.763) or a categorical variable (NLR ≤4.3 vs NLR >4.3) with a hazard ratio of 3.100 (95% confidence interval: 1.299-7.402), an elevated NLR was significantly associated with all-cause mortality in different models. A greater NLR at baseline was remarkably associated with a higher all-cause mortality in hospitalized patients with CKD-related PH.

Extra domain A-containing fibronectin in pulmonary hypertension and treatment effects of a function-blocking antibody

AIMS

Pulmonary vascular and right ventricular (RV) remodelling processes are important for development and progression of pulmonary hypertension (PH). The current study analysed the functional role of the extra domain A-containing fibronectin (ED-A+ Fn) for the development of PH by comparing ED-A+ Fn knockout (KO) and wild-type (WT) mice as well as the effects of an antibody-based therapeutic approach in a model of monocrotaline (MCT)-induced PH, which will be validated in a model of Sugen 5416/hypoxia-induced PH.

METHODS AND RESULTS

PH was induced using MCT (PH mice). Sixty-nine mice were divided into the following groups: sham-treated controls (WT: n = 7; KO: n = 7), PH mice without specific treatment (WT: n = 12; KO: n = 10), PH mice treated with a dual endothelin receptor antagonist (macitentan; WT: n = 6; KO: n = 11), WT PH mice treated with the F8 antibody, specifically recognizing ED-A+ Fn, (n = 8), and WT PH mice treated with an antibody of irrelevant antigen specificity (KSF, n = 8). Compared to controls, WT_PH mice showed a significant elevation of the RV systolic pressure (P = 0.04) and RV functional impairment including increased basal RV (P = 0.016) diameter or tricuspid annular plane systolic excursion (P = 0.008). In contrast, KO PH did not show such effects compared to controls (P = n.s.). In WT_PH mice treated with F8, haemodynamic and echocardiographic parameters were significantly improved compared to untreated WT_PH mice or those treated with the KSF antibody (P < 0.05). On the microscopic level, KO_PH mice showed significantly less tissue damage compared to the WT_PH mice (P = 0.008). Furthermore, lung tissue damage could significantly be reduced after F8 treatment (P = 0.04). Additionally, these findings could be verified in the Sugen 5416/hypoxia mouse model, in which F8 significantly improved echocardiographic, haemodynamic, and histologic parameters.

CONCLUSION

ED-A+ Fn is of crucial importance for PH pathogenesis representing a promising therapeutic target in PH. We here show a novel therapeutic approach using antibody-mediated functional blockade of ED-A+ Fn capable of attenuating and partially reversing PH-associated tissue remodelling.

G6pdN126D Variant Increases the Risk of Developing VEGFR (Vascular Endothelial Growth Factor Receptor) Blocker-Induced Pulmonary Vascular Disease

BACKGROUND

G6PD (glucose-6-phosphate-dehydrogenase) is a key enzyme in the glycolytic pathway and has been implicated in the pathogenesis of cancer and pulmonary hypertension-associated vascular remodeling. Here, we investigated the role of an X-linked G6pd mutation (N126D polymorphism), which is known to increase the risk of cardiovascular disease in individuals from sub-Saharan Africa and many others with African ancestry, in the pathogenesis of pulmonary hypertension induced by a vascular endothelial cell growth factor receptor blocker used for treating cancer.

METHODS AND RESULTS

CRISPR-Cas9 genome editing was used to generate the G6pd variant (N126D; G6pdN126D) in rats. A single dose of the vascular endothelial cell growth factor receptor blocker sugen-5416 (SU; 20 mg/kg in DMSO), which is currently in a Phase 2/3 clinical trial for cancer treatment, was subcutaneously injected into G6pdN126D rats and their wild-type littermates. After 8 weeks of normoxic conditions, right ventricular pressure and hypertrophy, pulmonary artery remodeling, the metabolic profile, and cytokine expression were assessed. Right ventricular pressure and pulmonary arterial wall thickness were increased in G6PDN126D+SU/normoxic rats. Simultaneously, levels of oxidized glutathione, inositol triphosphate, and intracellular Ca2+ were increased in the lungs of G6PDN126D+SU/normoxic rats, whereas nitric oxide was decreased. Also increased in G6PDN126D+SU/normoxic rats were pulmonary levels of plasminogen activator inhibitor-1, thrombin-antithrombin complex, and expression of proinflammatory cytokines CCL3 (chemokine [C-C motif] ligand), CCL5, and CCL7.

CONCLUSIONS

Our results suggest G6PDN126D increases inositol triphosphate-Ca2+ signaling, inflammation, thrombosis, and hypertrophic pulmonary artery remodeling in SU-treated rats. This suggests an increased risk of vascular endothelial cell growth factor receptor blocker-induced pulmonary hypertension in those carrying this G6PD variant.

Pathology and pathobiology of pulmonary hypertension: current insights and future directions

In recent years, major advances have been made in the understanding of the cellular and molecular mechanisms driving pulmonary vascular remodelling in various forms of pulmonary hypertension, including pulmonary arterial hypertension, pulmonary hypertension associated with left heart disease, pulmonary hypertension associated with chronic lung disease and hypoxia, and chronic thromboembolic pulmonary hypertension. However, the survival rates for these different forms of pulmonary hypertension remain unsatisfactory, underscoring the crucial need to more effectively translate innovative scientific knowledge into healthcare interventions. In these proceedings of the 7th World Symposium on Pulmonary Hypertension, we delve into recent developments in the field of pathology and pathophysiology, prioritising them while questioning their relevance to different subsets of pulmonary hypertension. In addition, we explore how the latest omics and other technological advances can help us better and more rapidly understand the myriad basic mechanisms contributing to the initiation and progression of pulmonary vascular remodelling. Finally, we discuss strategies aimed at improving patient care, optimising drug development, and providing essential support to advance research in this field.

Methyltransferase-Like 3-Mediated N6-Methyladenosine RNA Methylation Regulates Hypoxia-Induced Pulmonary Arterial Smooth Muscle Cell Pyroptosis by Targeting PTEN

BACKGROUND

Pulmonary hypertension is a rare, progressive disorder that can lead to right ventricular hypertrophy, right heart failure, and even sudden death. N6-methyladenosine modification and the main methyltransferase that mediates it, methyltransferase-like (METTL) 3, exert important effects on many biological and pathophysiological processes. However, the role of METTL3 in pyroptosis remains unclear.

METHODS AND RESULTS

Here, we characterized the role of METTL3 and the underlying cellular and molecular mechanisms of pyroptosis, which is involved in pulmonary hypertension. METTL3 was downregulated in a pulmonary hypertension mouse model and in hypoxia-exposed pulmonary artery smooth muscle cell. The small interfering RNA-induced silencing of METTL3 decreased the m6A methylation levels and promoted pulmonary artery smooth muscle cell pyroptosis, mimicking the effects of hypoxia. In contrast, overexpression of METTL3 suppressed hypoxia-induced pulmonary artery smooth muscle cell pyroptosis. Mechanistically, we identified the phosphate and tension homology deleted on chromosome 10 (PTEN) gene as a target of METTL3-mediated m6A modification, and methylated phosphate and tension homology deleted on chromosome 10 mRNA was subsequently recognized by the m6A "reader" protein insulin-like growth factor 2 mRNA-binding protein 2, which directly bound to the m6A site on phosphate and tension homology deleted on chromosome 10 mRNA and enhanced its stability.

CONCLUSIONS

These results identify a new signaling pathway, the METTL3/phosphate and tension homology deleted on chromosome 10/insulin-like growth factor 2 mRNA-binding protein 2 axis, that participates in the regulation of hypoxia-induced pyroptosis.

Evaluation of pulmonary arterial stiffness in post mild COVID-19 patients: a pilot prospective study

BACKGROUND

Our primary goal was to utilize pulmonary arterial stiffness (PAS) to demonstrate the early alterations in the pulmonary vascular area in individuals with prior COVID-19 illness who had not undergone hospitalization.

METHODS

In total, 201 patients with prior COVID-19 infection without hospitalization and 195 healthy, age- and sex-matched individuals without a history of COVID-19 disease were included in this prospective analysis. The PAS value for each patient was calculated by dividing the mean peak pulmonary flow velocity by the pulmonary flow acceleration time.

RESULTS

The measured PAS was 10.2 ± 4.11 Hz/msec in post-COVID-19 participants and 8.56 ± 1.47 Hz/msec in healthy subjects (P < 0.001). Moreover, pulmonary artery acceleration time was significantly lower in patients with a prior history of COVID-19. Multivariable logistic regression analysis revealed that PAS was significantly connected to a prior COVID-19 illness (odds ratio, 1.267; 95% confidence interval, 1.142-1.434; P < 0.001). The optimal cutoff point for detecting a prior COVID-19 disease for PAS was 10.1 (sensitivity, 70.2%; specificity, 87.7%).

CONCLUSIONS

This might be the first investigation to reveal that patients with a history of COVID-19 had higher PAS values compared to those without COVID-19. The results of the investigation may indicate the need of regular follow up of COVID-19 patients for the development of pulmonary arterial hypertension, especially during the post-COVID-19 interval.

CD137 Signaling Mediates Pulmonary Artery Endothelial Cell Proliferation Under Hypoxia By Regulating Mitochondrial Dynamics

Altered mitochondrial dynamics affect pulmonary artery endothelial cells (PAECs) proliferation, contributing to the development of pulmonary hypertension. CD137 signaling promotes mitochondrial fission. We hypothesize CD137 signaling is involved in the excessive proliferation of PAECs. The levels of CD137 protein were increased in the lung tissue of hypoxic mice and hypoxic-stimulated PAECs. Activation of CD137 signal in hypoxic-PAECs upregulated the levels of hypoxia-inducible factor-2α (HIF-2α), glucose transporters type 4, the lactate transporter monocarboxylate transporter 4, key glycolysis rate-limiting enzymes and promoted mitochondrial division; moreover, increased glucose uptake, lactic acid and ATP production and proliferative cells were observed in these PAECs. Whereas, knockdown HIF-2α reversed CD137 signal-mediated effects in PAECs mentioned above. Compared with wild-type mice, the proliferation of PAECs and the percentage of vascular lateral wall thickness decreased in CD137 knockout mice. Together, CD137 signal participated in pulmonary vascular remodeling through the regulation of mitochondrial dynamics dependent on HIF-2α in PAECs.

PDZ-Binding Kinase, a Novel Regulator of Vascular Remodeling in Pulmonary Arterial Hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is high blood pressure in the lungs that originates from structural changes in small resistance arteries. A defining feature of PAH is the inappropriate remodeling of pulmonary arteries (PA) leading to right ventricle failure and death. Although treatment of PAH has improved, the long-term prognosis for patients remains poor, and more effective targets are needed.

METHODS

Gene expression was analyzed by microarray, RNA sequencing, quantitative polymerase chain reaction, Western blotting, and immunostaining of lung and isolated PA in multiple mouse and rat models of pulmonary hypertension (PH) and human PAH. PH was assessed by digital ultrasound, hemodynamic measurements, and morphometry.

RESULTS

Microarray analysis of the transcriptome of hypertensive rat PA identified a novel candidate, PBK (PDZ-binding kinase), that was upregulated in multiple models and species including humans. PBK is a serine/threonine kinase with important roles in cell proliferation that is minimally expressed in normal tissues but significantly increased in highly proliferative tissues. PBK was robustly upregulated in the medial layer of PA, where it overlaps with markers of smooth muscle cells. Gain-of-function approaches show that active forms of PBK increase PA smooth muscle cell proliferation, whereas silencing PBK, dominant negative PBK, and pharmacological inhibitors of PBK all reduce proliferation. Pharmacological inhibitors of PBK were effective in PH reversal strategies in both mouse and rat models, providing translational significance. In a complementary genetic approach, PBK was knocked out in rats using CRISPR/Cas9 editing, and loss of PBK prevented the development of PH. We found that PBK bound to PRC1 (protein regulator of cytokinesis 1) in PA smooth muscle cells and that multiple genes involved in cytokinesis were upregulated in experimental models of PH and human PAH. Active PBK increased PRC1 phosphorylation and supported cytokinesis in PA smooth muscle cells, whereas silencing or dominant negative PBK reduced cytokinesis and the number of cells in the G2/M phase of the cell cycle.

CONCLUSIONS

PBK is a newly described target for PAH that is upregulated in proliferating PA smooth muscle cells, where it contributes to proliferation through changes in cytokinesis and cell cycle dynamics to promote medial thickening, fibrosis, increased PA resistance, elevated right ventricular systolic pressure, right ventricular remodeling, and PH.

Exploring the pathogenesis of pulmonary vascular disease

Pulmonary hypertension (PH) is a complex cardiopulmonary disorder impacting the lung vasculature, resulting in increased pulmonary vascular resistance that leads to right ventricular dysfunction. Pulmonary hypertension comprises of 5 groups (PH group 1 to 5) where group 1 pulmonary arterial hypertension (PAH), results from alterations that directly affect the pulmonary arteries. Although PAH has a complex pathophysiology that is not completely understood, it is known to be a multifactorial disease that results from a combination of genetic, epigenetic and environmental factors, leading to a varied range of symptoms in PAH patients. PAH does not have a cure, its incidence and prevalence continue to increase every year, resulting in higher morbidity and mortality rates. In this review, we discuss the different pathologic mechanisms with a focus on epigenetic modifications and their roles in the development and progression of PAH. These modifications include DNA methylation, histone modifications, and microRNA dysregulation. Understanding these epigenetic modifications will improve our understanding of PAH and unveil novel therapeutic targets, thus steering research toward innovative treatment strategies.

Prognostic value of pulmonary diffusing capacity for carbon monoxide and ventilation-perfusion SPECT findings in pulmonary arterial hypertension

Reduced pulmonary diffusing capacity for carbon monoxide (DLCO) can be observed in pulmonary arterial hypertension (PAH) and associates with increased mortality. However, the prognostic value of DLCO when corrected for haemoglobin (DLCOc), an independent modifier of DLCO, remains understudied. Additionally, the prognostic role of ventilation (V)-perfusion (Q) emission computed tomography (V/Q SPECT) findings in patients with PAH, which may concurrently be performed to rule out chronic thromboembolic pulmonary hypertension, is uncertain. A retrospective cohort study was conducted on 152 patients with PAH referred to a tertiary hospital for evaluation from January 2011 to January 2020. Lung function tests, clinical data and V/Q SPECT were ascertained. Cox regression analysis was performed to evaluate the association between DLCOc, DLCO and V/Q SPECT defects at referral with all-cause mortality. In equally adjusted Cox regression analysis, each percentage increase in DLCOc % predicted (%pred) (hazard ratio (HR) 0.97; 95% CI: 0.94-0.99) and DLCO%pred (HR 0.97; 95% CI: 0.94-0.99) was similarly associated with all-cause mortality. There was no detectable difference in area under the curve for prediction of all-cause mortality by DLCOc%pred and DLCO%pred (C-index 0.71 and 0.72, respectively, P = 0.85 for difference). None of the defects noted on V/Q SPECT were significantly associated with mortality, but mismatched defects were associated with lower values of DLCOc%pred and DLCO%pred. DLCOc%pred and DLCO%pred perform equally as prognostic markers in PAH, supporting the use of either metric when available for prognostic stratification.

Immature reticulocyte fraction: A novel biomarker of hemodynamic severity in pulmonary arterial hypertension

Various erythropoietic abnormalities are highly prevalent among patients with pulmonary arterial hypertension (PAH) and associated with worse disease severity. Given the poorly understood yet important roles of dysregulated erythropoiesis and iron metabolism in PAH, we sought to further characterize the hematologic and iron profiles in PAH and their relationship to PAH severity. We recruited 67 patients with PAH and 13 healthy controls. Hemodynamics attained within 1 year of blood sample collection were available for 36 patients. Multiple hematologic, iron, and inflammatory parameters were evaluated for their association with hemodynamics. The subset with hemodynamic data consisted of 29 females (81%). The most common etiologies were idiopathic PAH (47%) and connective tissue disease-related PAH (33%). 19 (53%) had functional class 3 or 4 symptomatology, and 12 (33%) were on triple pulmonary vasodilator therapy. Immature reticulocyte fraction (IRF) had significant positive correlations with mean pulmonary artery (PA) pressure (mPAP) (0.59, p < 0.001), pulmonary vascular resistance (0.52, p = 0.001), and right atrial pressure (0.46, p = 0.005), and significant negative correlations with cardiac index (-0.43, p = 0.009), PA compliance (PAC) (-0.60, p < 0.001), stroke volume index (SVI) (-0.57, p < 0.001), and mixed venous oxygen saturation (-0.51, p = 0.003). IRF correlated with markers of iron deficiency (ID) and erythropoiesis. On multivariable linear regression, IRF was associated with elevated mPAP and reduced SVI and PAC independent of EPO levels, transferrin saturation, and soluble transferrin receptor levels. We identified IRF as a novel and potent biomarker of PAH hemodynamic severity, possibly related to its associations with erythropoiesis, ID, and tissue hypoxia.

Transcriptomic profiling highlights cell proliferation in the progression of experimental pulmonary hypertension in rats

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by pulmonary vascular remolding and occlusion, leading to the elevated pulmonary arterial pressures, right ventricular hypertrophy, and eventual heart failure if left untreated. Understanding the molecular mechanisms underlying the development and progression of pulmonary hypertension (PH) is crucial for devising efficient therapeutic approaches for the disease. Lung homogenates were collected weekly and underwent RNA-sequencing in the monocrotaline (MCT)-induced PH rat model to explore genes associated with PH progression. Statistical analyses revealed 1038, 1244, and 3125 significantly altered genes (P < 0.05, abs (log2fold change) > log21.5) between control and MCT-exposed rats during the first, second, and third week, respectively. Pathway enrichment analyses revealed involvement of cell cycle and innate immune system for the upregulated genes, GPCR and VEGF signaling for the downregulated genes. Furthermore, qRT-PCR validated upregulation of representative genes associated with cell cycle including Cdc25c (cell division cycle 25C), Cdc45, Top2a (topoisomerase IIα), Ccna2 (cyclin A2) and Ccnb1 (cyclin B1). Western blot and immunofluorescence analysis confirmed increases in PCNA, Ccna2, Top2a, along with other proliferation markers in the lung tissue of MCT-treated rats. In summary, RNA sequencing data highlights the significance of cell proliferation in progression of rodent PH.

Crocin's role in modulating MMP2/TIMP1 and mitigating hypoxia-induced pulmonary hypertension in mice

To explore the molecular pathogenesis of pulmonary arterial hypertension (PAH) and identify potential therapeutic targets, we performed transcriptome sequencing of lung tissue from mice with hypoxia-induced pulmonary hypertension. Our Gene Ontology analysis revealed that "extracellular matrix organization" ranked high in the biological process category, and matrix metallopeptidases (MMPs) and other proteases also played important roles in it. Moreover, compared with those in the normoxia group, we confirmed that MMPs expression was upregulated in the hypoxia group, while the hub gene Timp1 was downregulated. Crocin, a natural MMP inhibitor, was found to reduce inflammation, decrease MMPs levels, increase Timp1 expression levels, and attenuate hypoxia-induced pulmonary hypertension in mice. In addition, analysis of the cell distribution of MMPs and Timp1 in the human lung cell atlas using single-cell RNAseq datasets revealed that MMPs and Timp1 are mainly expressed in a population of fibroblasts. Moreover, in vitro experiments revealed that crocin significantly inhibited myofibroblast proliferation, migration, and extracellular matrix deposition. Furthermore, we demonstrated that crocin inhibited TGF-β1-induced fibroblast activation and regulated the pulmonary arterial fibroblast MMP2/TIMP1 balance by inhibiting the TGF-β1/Smad3 signaling pathway. In summary, our results indicate that crocin attenuates hypoxia-induced pulmonary hypertension in mice by inhibiting TGF-β1-induced myofibroblast activation.

Fibroblasts in Pulmonary Hypertension: Roles and Molecular Mechanisms

Fibroblasts, among the most prevalent and widely distributed cell types in the human body, play a crucial role in defining tissue structure. They do this by depositing and remodeling extracellular matrixes and organizing functional tissue networks, which are essential for tissue homeostasis and various human diseases. Pulmonary hypertension (PH) is a devastating syndrome with high mortality, characterized by remodeling of the pulmonary vasculature and significant cellular and structural changes within the intima, media, and adventitia layers. Most research on PH has focused on alterations in the intima (endothelial cells) and media (smooth muscle cells). However, research over the past decade has provided strong evidence of the critical role played by pulmonary artery adventitial fibroblasts in PH. These fibroblasts exhibit the earliest, most dramatic, and most sustained proliferative, apoptosis-resistant, and inflammatory responses to vascular stress. This review examines the aberrant phenotypes of PH fibroblasts and their role in the pathogenesis of PH, discusses potential molecular signaling pathways underlying these activated phenotypes, and highlights areas of research that merit further study to identify promising targets for the prevention and treatment of PH.

Systemic scleroderma: Review and updated approach and case description to addressing pulmonary arterial hypertension and idiopathic pulmonary fibrosis: A dual challenge in treatment

Pulmonary arterial hypertension (PAH), idiopathic pulmonary fibrosis (IPF), and scleroderma (SSc) are three interrelated medical conditions that can result in significant morbidity and mortality. Pulmonary hypertension, a condition marked by high blood pressure in the lungs, can lead to heart failure and other complications. Idiopathic pulmonary fibrosis, a progressive lung disease characterised by scarring of lung tissue, can cause breathing difficulties and impaired oxygenation. Scleroderma, an autoimmune disease, can induce thickening and hardening of the skin and internal organs, including the lungs, leading to pulmonary fibrosis and hypertension. Currently, there is no cure for any of these conditions. However, early detection and proper management can improve the quality of life and prognosis of a patient. This review focusses on PH and IPF in patients with SSc, providing information on the causes, symptoms, and treatment of these conditions, together with illustrative images. It also provides an overview of interrelated medical conditions: PH, IPF, and SSc. It emphasises the importance of early detection and proper management to improve patient quality of life and prognosis.

Pulmonary arterial hypertension: Sex matters

Pulmonary arterial hypertension (PAH) is a complex disease of multifactorial origin. While registries have demonstrated that women are more susceptible to the disease, females with PAH have superior right ventricle (RV) function and a better prognosis than their male counterparts, a phenomenon referred to as the 'estrogen paradox'. Numerous pre-clinical studies have investigated the involvement of sex hormones in PAH pathobiology, often with conflicting results. However, recent advances suggest that abnormal estrogen synthesis, metabolism and signalling underpin the sexual dimorphism of this disease. Other sex hormones, such as progesterone, testosterone and dehydroepiandrosterone may also play a role. Several non-hormonal factor including sex chromosomes and epigenetics have also been implicated. Though the underlying pathophysiological mechanisms are complex, several compounds that modulate sex hormones levels and signalling are under investigation in PAH patients. Further elucidation of the estrogen paradox will set the stage for the identification of additional therapeutic targets for this disease.

How Would I Treat My Own Chronic Thromboembolic Pulmonary Hypertension in the Perioperative Period?

Chronic thromboembolic pulmonary hypertension (CTEPH) results from an incomplete resolution of acute pulmonary embolism, leading to occlusive organized thrombi, vascular remodeling, and associated microvasculopathy with pulmonary hypertension (PH). A definitive CTEPH diagnosis requires PH confirmation by right-heart catheterization and evidence of chronic thromboembolic pulmonary disease on imaging studies. Surgical removal of the organized fibrotic material by pulmonary endarterectomy (PEA) under deep hypothermic circulatory arrest represents the treatment of choice. One-third of patients with CTEPH are not deemed suitable for surgical treatment, and medical therapy or interventional balloon pulmonary angioplasty presents alternative treatment options. Pulmonary endarterectomy in patients with technically operable disease significantly improves symptoms, functional capacity, hemodynamics, and quality of life. Perioperative mortality is <2.5% in expert centers where a CTEPH multidisciplinary team optimizes patient selection and ensures the best preoperative optimization according to individualized risk assessment. Despite adequate pulmonary artery clearance, patients might be prone to perioperative complications, such as right ventricular maladaptation, airway bleeding, or pulmonary reperfusion injury. These complications can be treated conventionally, but extracorporeal membrane oxygenation has been included in their management recently. Patients with residual PH post-PEA should be considered for medical or percutaneous interventional therapy.

Pulmonary arterial hypertension nanotherapeutics: New pharmacological targets and drug delivery strategies

Pulmonary arterial hypertension (PAH) is a rare, serious, and incurable disease characterized by high lung pressure. PAH-approved drugs based on conventional pathways are still not exhibiting favorable therapeutic outcomes. Drawbacks like short half-lives, toxicity, and teratogenicity hamper effectiveness, clinical conventionality, and long-term safety. Hence, approaches like repurposing drugs targeting various and new pharmacological cascades and/or loaded in non-toxic/efficient nanocarrier systems are being investigated lately. This review summarizes the status of conventional, repurposed, either in vitro, in vivo, and/or in clinical trials of PAH treatment. In-depth description, discussion, and classification of the new pharmacological targets and nanomedicine strategies with a description of all the nanocarriers that showed promising efficiency in delivering drugs are discussed. Ultimately, an illustration of the different nucleic acids tailored and nanoencapsulated within different types of nanocarriers to restore the pathways affected by this disease is presented.

Anesthetic management of children with medically refractory pulmonary hypertension undergoing surgical Potts shunt

INTRODUCTION

Pulmonary hypertension in children is associated with high rates of adverse events under anesthesia. In children who have failed medical therapy, a posttricuspid shunt such as a Potts shunt can offload the right ventricle and possibly delay or replace the need for lung transplantation. Intraoperative management of this procedure, during which an anastomosis between the pulmonary artery and the descending aorta is created, is complex and requires a deep understanding of the pathophysiology of acute and chronic right ventricular failure. This retrospective case review describes the intraoperative management of children undergoing surgical creation of a Potts shunt at a single center.

METHODS

A retrospective case review of all patients under the age of 18 who underwent Potts shunt between April 2013 and June 2022. Medical records were examined, and clinical data of demographics, intraoperative vital signs, anesthetic management, and postoperative outcomes were extracted.

RESULTS

Twenty-nine children with medically refractory pulmonary hypertension underwent surgical Potts shunts with a median age of 12 years (range 4 months to 17.4 years). Nineteen Potts shunts (65%) were placed via thoracotomy and 10 (35%) were placed via median sternotomy with use of cardiopulmonary bypass. Ketamine was the most frequently utilized induction agent (17 out of 29, 59%), and the majority of patients were initiated on vasopressin prior to intubation (20 out of 29, 69%). Additional inotropic support with epinephrine (45%), milrinone (28%), norepinephrine (17%), and dobutamine (14%) was used prior to shunt placement. Following opening of the Potts shunt, hemodynamic support was continued with vasopressin (66%), epinephrine (62%), milrinone (59%), dobutamine (14%), and norepinephrine (10%). Major intraoperative complications included severe hypoxemia (21 out of 29, 72%) and hypotension requiring boluses of epinephrine (10 out of 29, 34.5%) but no patient suffered intraoperative cardiac arrest. There were four in-hospital mortalities.

DISCUSSION

A Potts shunt offers another palliative option for children with medically refractory pulmonary hypertension. General anesthesia in these children carries high risk for pulmonary hypertensive crises. Anesthesiologists must understand underlying physiological mechanisms responsble for acute hemodynaic decompensation during acute pulmonary hypertneisve crises. Severe physiological perturbations imposed by thoracic surgery and use of cardiopulmonay bypass can be mitigated by aggresive heodynamic support of ventricle function and maintainence of systemic vascular resistance. Early use of vasopressin, before or immidiately after anesthesia induction, in combination with other inotropes is a useful agent during the perioperative care of thes. Early use of vasopressin during anesthesia induction, and aggressive inotropic support of right ventricular function can help mitigate effects of induction and intubation, single-lung ventilation, and cardiopulmonary bypass.

CONCLUSIONS

Our single center expereince shows that the Potts shunt surgery, despite high short-term mortaility, may offer another option for palliation in children with medically refractory pulmonary hypertension.

Correlation between pulmonary vascular performance and hemodynamics in patients with pulmonary arterial hypertension

OBJECTIVE

To explore the correlation between pulmonary vascular performance and hemodynamics in patients with pulmonary arterial hypertension (PAH), using right heart catheterization (RHC) and intravascular ultrasound (IVUS).

METHOD

A total of 60 patients underwent RHC and IVUS examinations. Of these, 27 patients were diagnosed with PAH associated with connective tissue diseases (PAH-CTD group), 18 patients were diagnosed with other types of PAH (other-types-PAH group), and 15 patients were without PAH (control group). The hemodynamics and morphological parameters of pulmonary vessels in PAH patients were assessed using RHC and IVUS.

RESULTS

There were statistically significant differences in right atrial pressure (RAP), pulmonary artery systolic pressure (sPAP), pulmonary artery diastolic pressure (dPAP), mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR) values between the PAH-CTD group, other-types-PAH group, and the control group (P < .05). No statistically significant difference was noticed in pulmonary artery wedge pressure (PAWP) and cardiac output (CO) values between these three groups (P > .05). The mean wall thickness (MWT), wall thickness percentage (WTP), pulmonary vascular compliance, dilation, elasticity modulus, stiffness index β, and other indicators were significantly different between these three groups (P < .05). Pairwise comparison showed that the average levels of pulmonary vascular compliance and dilation in PAH-CTD group and other-types-PAH group were lower than those in control group, while the average levels of elastic modulus and stiffness index β were higher than those in control group.

CONCLUSION

Pulmonary vascular performance deteriorates in PAH patients, and the performance is better in PAH-CTD patients than in other types of PAH.

Isogenic pairs of induced-pluripotent stem-derived endothelial cells identify DYRK1A/PPARG/EGR1 pathway is responsible for Down syndrome-associated pulmonary hypertension

Down syndrome (DS) is the most prevalent chromosomal disorder associated with a higher incidence of pulmonary arterial hypertension (PAH). The dysfunction of vascular endothelial cells (ECs) is known to cause pulmonary arterial remodeling in PAH, although the physiological characteristics of ECs harboring trisomy 21 (T21) are still unknown. In this study, we analyzed the human vascular ECs by utilizing the isogenic pairs of T21-induced pluripotent stem cells (iPSCs) and corrected disomy 21 (cDi21)-iPSCs. In T21-iPSC-derived ECs, apoptosis and mitochondrial reactive oxygen species (mROS) were significantly increased, and angiogenesis and oxygen consumption rate (OCR) were significantly impaired as compared with cDi21-iPSC-derived ECs. The RNA-sequencing identified that EGR1 on chromosome 5 was significantly upregulated in T21-ECs. Both EGR1 suppression by siRNA and pharmacological inhibitor could recover the apoptosis, mROS, angiogenesis, and OCR in T21-ECs. Alternately, the study also revealed that DYRK1A was responsible to increase EGR1 expression via PPARG suppression, and that chemical inhibition of DYRK1A could restore the apoptosis, mROS, angiogenesis, and OCR in T21-ECs. Finally, we demonstrated that EGR1 was significantly upregulated in the pulmonary arterial ECs from lung specimens of a patient with DS and PAH. In conclusion, DYRK1A/PPARG/EGR1 pathway could play a central role for the pulmonary EC functions and thus be associated with the pathogenesis of PAH in DS.

A Review of Serotonin in the Developing Lung and Neonatal Pulmonary Hypertension

Serotonin (5-HT) is a bioamine that has been implicated in the pathogenesis of pulmonary hypertension (PH). The lung serves as an important site of 5-HT synthesis, uptake, and metabolism with signaling primarily regulated by tryptophan hydroxylase (TPH), the 5-HT transporter (SERT), and numerous unique 5-HT receptors. The 5-HT hypothesis of PH was first proposed in the 1960s and, since that time, preclinical and clinical studies have worked to elucidate the role of 5-HT in adult PH. Over the past several decades, accumulating evidence from both clinical and preclinical studies has suggested that the 5-HT signaling pathway may play an important role in neonatal cardiopulmonary transition and the development of PH in newborns. The expression of TPH, SERT, and the 5-HT receptors is developmentally regulated, with alterations resulting in pulmonary vasoconstriction and pulmonary vascular remodeling. However, much remains unknown about the role of 5-HT in the developing and newborn lung. The purpose of this review is to discuss the implications of 5-HT on fetal and neonatal pulmonary circulation and summarize the existing preclinical and clinical literature on 5-HT in neonatal PH.

Unleashing the Potential of Nrf2: A Novel Therapeutic Target for Pulmonary Vascular Remodeling

Pulmonary vascular remodeling, characterized by the thickening of all three layers of the blood vessel wall, plays a central role in the pathogenesis of pulmonary hypertension (PH). Despite the approval of several drugs for PH treatment, their long-term therapeutic effect remains unsatisfactory, as they mainly focus on vasodilation rather than addressing vascular remodeling. Therefore, there is an urgent need for novel therapeutic targets in the treatment of PH. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a vital transcription factor that regulates endogenous antioxidant defense and emerges as a novel regulator of pulmonary vascular remodeling. Growing evidence has suggested an involvement of Nrf2 and its downstream transcriptional target in the process of pulmonary vascular remodeling. Pharmacologically targeting Nrf2 has demonstrated beneficial effects in various diseases, and several Nrf2 inducers are currently undergoing clinical trials. However, the exact potential and mechanism of Nrf2 as a therapeutic target in PH remain unknown. Thus, this review article aims to comprehensively explore the role and mechanism of Nrf2 in pulmonary vascular remodeling associated with PH. Additionally, we provide a summary of Nrf2 inducers that have shown therapeutic potential in addressing the underlying vascular remodeling processes in PH. Although Nrf2-related therapies hold great promise, further research is necessary before their clinical implementation can be fully realized.

Identification of monocyte-associated pathways participated in the pathogenesis of pulmonary arterial hypertension based on omics-data

Pulmonary arterial hypertension (PAH) is one kind of chronic and uncurable diseases that can cause heart failure. Immune microenvironment plays a significant role in PAH. The aim of this study was to assess the role of immune cell infiltration in the pathogenesis of PAH. Differentially expressed genes based on microarray data were enriched in several immune-related pathways. To evaluate the immune cell infiltration, based on the microarray data sets in the GEO database, we used both ssGSEA and the CIBERSORT algorithm. Additionally, single-cell RNA sequencing (scRNA-seq) data was used to further explicit the specific role and intercellular communications. Then receiver operating characteristic curves and least absolute shrinkage and selection operator were used to discover and test the potential diagnostic biomarkers for PAH. Both the immune cell infiltration analyses based on the microarray data sets and the cell proportion in scRNA-seq data exhibited a significant downregulation in the infiltration of monocytes in PAH. Then, the intercellular communications showed that the interaction weighs of most immune cells, including monocytes changed between the control and PAH groups, and the ITGAL-ITGB2 and ICAM signaling pathways played critical roles in this process. In addition, ITGAM and ICAM2 displayed good diagnosis values in PAH. This study implicated that the change of monocyte was one of the key immunologic features of PAH. Monocyte-associated ICAM-1 and ITGAL-ITGB2 signaling pathways might be involved in the pathogenesis of PAH.

Macitentan in the Young-Mid-term Outcomes of Patients with Pulmonary Hypertensive Vascular Disease treated in a Pediatric Tertiary Care Center

BACKGROUND

Pulmonary hypertension (PH) is a severe hemodynamic condition with high morbidity and mortality. Approved targeted therapies are limited for pediatric subjects, and treatments are widely adopted from adult algorithms. Macitentan is a safe and effective drug used for adult PH, but data on pediatric patients are limited. In this prospective single-center study, we investigated mid- and long-term effects of macitentan in children with advanced pulmonary hypertensive vascular disease.

METHODS

Twenty-four patients were enrolled in the study for treatment with macitentan. Efficacy was determined by echo parameters and brain natriuretic peptide levels (BNP) at 3 months and 1 year. For detailed analysis, the entire cohort was subgrouped into patients with congenital heart disease-related PH (CHD-PH) and non-CHD-PH patients, respectively.

RESULTS

Mean age of the patients was 10.7 ± 7.6 years; median observation period was 36 months. Twenty of 24 patients were on additional sildenafil and/or prostacyclins. Two of 24 patients discontinued because of peripheral edema. Within the entire cohort, BNP levels and all echo measures such as right ventricular systolic pressure (RVSP), right ventricular end-diastolic diameter (RVED), tricuspid annular plane systolic excursion (TAPSE), pulmonary velocity time integral (VTI), and pulmonary artery acceleration time (PAAT) improved significantly after 3 months (p ≤ 0.01), whereas in the long term significant improvement persisted for BNP levels (-16%), VTI (+14%) and PAAT (+11%) (p < 0.05). By subgroup analysis, non-CHD PH patients showed significant improvements in BNP levels (-57%) and all echo measures (TAPSE +21%, VTI +13%, PAAT +37%, RVSP -24%, RVED -12%) at 3 months (p ≤ 0.01), whereas at 12 months, improvements persisted (p < 0.05) except for RVSP and RVED (nonsignificant). In CHD-PH patients, none of the measures changed (nonsignificant). 6-MWD (distance walked in 6 minutes) slightly increased but was not statistically evaluated.

CONCLUSION

Data presented herein account for the largest cohort of severely affected pediatric patients receiving macitentan. Overall, macitentan was safe and associated with significant beneficial effects and sustained positive signals after 1 year, albeit in the long term disease progression remains a major concern. Our data suggest limited efficacy in CHD-related PH, whereas favorable outcomes were mainly driven by improvements in patients with PH not related to CHD. Larger studies are needed to verify these preliminary results and to prove efficacy of this drug in different pediatric PH entities.

Pathophysiology and pathogenic mechanisms of pulmonary hypertension: role of membrane receptors, ion channels, and Ca2+ signaling

The pulmonary circulation is a low-resistance, low-pressure, and high-compliance system that allows the lungs to receive the entire cardiac output. Pulmonary arterial pressure is a function of cardiac output and pulmonary vascular resistance, and pulmonary vascular resistance is inversely proportional to the fourth power of the intraluminal radius of the pulmonary artery. Therefore, a very small decrease of the pulmonary vascular lumen diameter results in a significant increase in pulmonary vascular resistance and pulmonary arterial pressure. Pulmonary arterial hypertension is a fatal and progressive disease with poor prognosis. Regardless of the initial pathogenic triggers, sustained pulmonary vasoconstriction, concentric vascular remodeling, occlusive intimal lesions, in situ thrombosis, and vascular wall stiffening are the major and direct causes for elevated pulmonary vascular resistance in patients with pulmonary arterial hypertension and other forms of precapillary pulmonary hypertension. In this review, we aim to discuss the basic principles and physiological mechanisms involved in the regulation of lung vascular hemodynamics and pulmonary vascular function, the changes in the pulmonary vasculature that contribute to the increased vascular resistance and arterial pressure, and the pathogenic mechanisms involved in the development and progression of pulmonary hypertension. We focus on reviewing the pathogenic roles of membrane receptors, ion channels, and intracellular Ca2+ signaling in pulmonary vascular smooth muscle cells in the development and progression of pulmonary hypertension.

HIV and Drug Use: A Tale of Synergy in Pulmonary Vascular Disease Development

Over the past two decades, with the advent and adoption of highly active anti-retroviral therapy, HIV-1 infection, a once fatal and acute illness, has transformed into a chronic disease with people living with HIV (PWH) experiencing increased rates of cardio-pulmonary vascular diseases including life-threatening pulmonary hypertension. Moreover, the chronic consequences of tobacco, alcohol, and drug use are increasingly seen in older PWH. Drug use, specifically, can have pathologic effects on the cardiovascular health of these individuals. The "double hit" of drug use and HIV may increase the risk of HIV-associated pulmonary arterial hypertension (HIV-PAH) and potentiate right heart failure in this population. This article explores the epidemiology and pathophysiology of PAH associated with HIV and recreational drug use and describes the proposed mechanisms by which HIV and drug use, together, can cause pulmonary vascular remodeling and cardiopulmonary hemodynamic compromise. In addition to detailing the proposed cellular and signaling pathways involved in the development of PAH, this article proposes areas ripe for future research, including the influence of gut dysbiosis and cellular senescence on the pathobiology of HIV-PAH. © 2023 American Physiological Society. Compr Physiol 13:4659-4683, 2023.

Novel Drugs for the Treatment of Pulmonary Arterial Hypertension: Where Are We Going?

Pulmonary arterial hypertension (PAH) is a progressive disease that despite advances in therapy is associated with a 7-year survival of approximately 50%. Several risk factors are associated with developing PAH, include methamphetamine use, scleroderma, human immunodeficiency virus, portal hypertension, and genetic predisposition. PAH can also be idiopathic. There are traditional pathways underlying the pathophysiology of PAH involving nitric oxide, prostacyclin, thromboxane A2, and endothelin-1, resulting in impaired vasodilation, enhanced vasoconstriction and proliferation in the pulmonary vasculature. Established PAH medications targets these pathways; however, this paper aims to discuss novel drugs for treating PAH by targeting new and alternative pathways.

Single-cell analysis of peripheral blood from high-altitude pulmonary hypertension patients identifies a distinct monocyte phenotype

Immune and inflammatory responses have an important function in the pathophysiology of pulmonary hypertension (PH). However, little is known about the immune landscape in peripheral circulation in patients with high-altitude pulmonary hypertension (HAPH). We apply single-cell transcriptomics to characterize the monocytes that are significantly enriched in the peripheral blood mononuclear cells (PBMC) of HAPH patients. We discover an increase in C1 (non-classical) and C2 (intermediate) monocytes in PBMCs and a decrease in hypoxia-inducible transcription factor-1α (HIF-1α) in all monocyte subsets associated with HAPH. In addition, we demonstrate that similar immune adaptations may exist in HAPH and PH. Overall, we characterize an immune cell atlas of the peripheral blood in HAPH patients. Our data provide evidence that specific monocyte subsets and HIF-1α downregulation might be implicated in the pathogenesis of HAPH.

Exercise-based rehabilitation programmes for pulmonary hypertension

BACKGROUND

Individuals with pulmonary hypertension (PH) have reduced exercise capacity and quality of life. Despite initial concerns that exercise training may worsen symptoms in this group, several studies have reported improvements in functional capacity and well-being following exercise-based rehabilitation.

OBJECTIVES

To evaluate the benefits and harms of exercise-based rehabilitation for people with PH compared with usual care or no exercise-based rehabilitation.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 28 June 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in people with PH comparing supervised exercise-based rehabilitation programmes with usual care or no exercise-based rehabilitation.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were 1. exercise capacity, 2. serious adverse events during the intervention period and 3. health-related quality of life (HRQoL). Our secondary outcomes were 4. cardiopulmonary haemodynamics, 5. Functional Class, 6. clinical worsening during follow-up, 7. mortality and 8. changes in B-type natriuretic peptide. We used GRADE to assess certainty of evidence.

MAIN RESULTS

We included eight new studies in the current review, which now includes 14 RCTs. We extracted data from 11 studies. The studies had low- to moderate-certainty evidence with evidence downgraded due to inconsistencies in the data and performance bias. The total number of participants in meta-analyses comparing exercise-based rehabilitation to control groups was 462. The mean age of the participants in the 14 RCTs ranged from 35 to 68 years. Most participants were women and classified as Group I pulmonary arterial hypertension (PAH). Study durations ranged from 3 to 25 weeks. Exercise-based programmes included both inpatient- and outpatient-based rehabilitation that incorporated both upper and lower limb exercise. The mean six-minute walk distance following exercise-based rehabilitation was 48.52 metres higher than control (95% confidence interval (CI) 33.42 to 63.62; I² = 72%; 11 studies, 418 participants; low-certainty evidence), the mean peak oxygen uptake was 2.07 mL/kg/min higher than control (95% CI 1.57 to 2.57; I² = 67%; 7 studies, 314 participants; low-certainty evidence) and the mean peak power was 9.69 W higher than control (95% CI 5.52 to 13.85; I² = 71%; 5 studies, 226 participants; low-certainty evidence). Three studies reported five serious adverse events; however, exercise-based rehabilitation was not associated with an increased risk of serious adverse event (risk difference 0, 95% CI -0.03 to 0.03; I² = 0%; 11 studies, 439 participants; moderate-certainty evidence). The mean change in HRQoL for the 36-item Short Form (SF-36) Physical Component Score was 3.98 points higher (95% CI 1.89 to 6.07; I² = 38%; 5 studies, 187 participants; moderate-certainty evidence) and for the SF-36 Mental Component Score was 3.60 points higher (95% CI 1.21 to 5.98 points; I² = 0%; 5 RCTs, 186 participants; moderate-certainty evidence). There were similar effects in the subgroup analyses for participants with Group 1 PH versus studies of groups with mixed PH. Two studies reported mean reduction in mean pulmonary arterial pressure following exercise-based rehabilitation (mean reduction: 9.29 mmHg, 95% CI -12.96 to -5.61; I² = 0%; 2 studies, 133 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

In people with PH, supervised exercise-based rehabilitation may result in a large increase in exercise capacity. Changes in exercise capacity remain heterogeneous and cannot be explained by subgroup analysis. It is likely that exercise-based rehabilitation increases HRQoL and is probably not associated with an increased risk of a serious adverse events. Exercise training may result in a large reduction in mean pulmonary arterial pressure. Overall, we assessed the certainty of the evidence to be low for exercise capacity and mean pulmonary arterial pressure, and moderate for HRQoL and adverse events. Future RCTs are needed to inform the application of exercise-based rehabilitation across the spectrum of people with PH, including those with chronic thromboembolic PH, PH with left-sided heart disease and those with more severe disease.

Animal Disease Models and Patient-iPS-Cell-Derived In Vitro Disease Models for Cardiovascular Biology-How Close to Disease?

Currently, zebrafish, rodents, canines, and pigs are the primary disease models used in cardiovascular research. In general, larger animals have more physiological similarities to humans, making better disease models. However, they can have restricted or limited use because they are difficult to handle and maintain. Moreover, animal welfare laws regulate the use of experimental animals. Different species have different mechanisms of disease onset. Organs in each animal species have different characteristics depending on their evolutionary history and living environment. For example, mice have higher heart rates than humans. Nonetheless, preclinical studies have used animals to evaluate the safety and efficacy of human drugs because no other complementary method exists. Hence, we need to evaluate the similarities and differences in disease mechanisms between humans and experimental animals. The translation of animal data to humans contributes to eliminating the gap between these two. In vitro disease models have been used as another alternative for human disease models since the discovery of induced pluripotent stem cells (iPSCs). Human cardiomyocytes have been generated from patient-derived iPSCs, which are genetically identical to the derived patients. Researchers have attempted to develop in vivo mimicking 3D culture systems. In this review, we explore the possible uses of animal disease models, iPSC-derived in vitro disease models, humanized animals, and the recent challenges of machine learning. The combination of these methods will make disease models more similar to human disease.

Histologic and proteomic remodeling of the pulmonary veins and arteries in a porcine model of chronic pulmonary venous hypertension

AIMS

In heart failure (HF), pulmonary venous hypertension (PVH) produces pulmonary hypertension (PH) with remodeling of pulmonary veins (PV) and arteries (PA). In a porcine PVH model, we performed proteomic-based bioinformatics to investigate unique pathophysiologic mechanisms mediating PA and PV remodeling.

METHODS AND RESULTS

Large PV were banded (PVH, n = 10) or not (Sham, n = 9) in piglets. At sacrifice, PV and PA were perfusion labelled for vessel-specific histology and proteomics. The PA and PV were separately sampled with laser-capture micro-dissection for mass spectrometry. Pulmonary vascular resistance [Wood Units; 8.6 (95% confidence interval: 6.3, 12.3) vs. 2.0 (1.7, 2.3)] and PA [19.9 (standard error of mean, 1.1) vs. 10.3 (1.1)] and PV [14.2 (1.2) vs. 7.6 (1.1)] wall thickness/external diameter (%) were increased in PVH (P < 0.05 for all). Similar numbers of proteins were identified in PA (2093) and PV (2085) with 94% overlap, but biological processes differed. There were more differentially expressed proteins (287 vs. 161), altered canonical pathways (17 vs. 3), and predicted upstream regulators (PUSR; 22 vs. 6) in PV than PA. In PA and PV, bioinformatics indicated activation of the integrated stress response and mammalian target of rapamycin signalling with dysregulated growth. In PV, there was also activation of Rho/Rho-kinase signalling with decreased actin cytoskeletal signalling and altered tight and adherens junctions, ephrin B, and caveolae-mediated endocytosis signalling; all indicating disrupted endothelial barrier function. Indeed, protein biomarkers and the top PUSR in PV (transforming growth factor-beta) suggested endothelial to mesenchymal transition in PV. Findings were similar in human autopsy specimens.

CONCLUSION

These findings provide new therapeutic targets to oppose pulmonary vascular remodeling in HF-related PH.

Emerging role of exosomes in vascular diseases

Exosomes are biological small spherical lipid bilayer vesicles secreted by most cells in the body. Their contents include nucleic acids, proteins, and lipids. Exosomes can transfer material molecules between cells and consequently have a variety of biological functions, participating in disease development while exhibiting potential value as biomarkers and therapeutics. Growing evidence suggests that exosomes are vital mediators of vascular remodeling. Endothelial cells (ECs), vascular smooth muscle cells (VSMCs), inflammatory cells, and adventitial fibroblasts (AFs) can communicate through exosomes; such communication is associated with inflammatory responses, cell migration and proliferation, and cell metabolism, leading to changes in vascular function and structure. Essential hypertension (EH), atherosclerosis (AS), and pulmonary arterial hypertension (PAH) are the most common vascular diseases and are associated with significant vascular remodeling. This paper reviews the latest research progress on the involvement of exosomes in vascular remodeling through intercellular information exchange and provides new ideas for understanding related diseases.

Molecular Mechanisms and Therapeutic Implications of Endothelial Dysfunction in Patients with Heart Failure

Heart failure is a complex medical syndrome that is attributed to a number of risk factors; nevertheless, its clinical presentation is quite similar among the different etiologies. Heart failure displays a rapidly increasing prevalence due to the aging of the population and the success of medical treatment and devices. The pathophysiology of heart failure comprises several mechanisms, such as activation of neurohormonal systems, oxidative stress, dysfunctional calcium handling, impaired energy utilization, mitochondrial dysfunction, and inflammation, which are also implicated in the development of endothelial dysfunction. Heart failure with reduced ejection fraction is usually the result of myocardial loss, which progressively ends in myocardial remodeling. On the other hand, heart failure with preserved ejection fraction is common in patients with comorbidities such as diabetes mellitus, obesity, and hypertension, which trigger the creation of a micro-environment of chronic, ongoing inflammation. Interestingly, endothelial dysfunction of both peripheral vessels and coronary epicardial vessels and microcirculation is a common characteristic of both categories of heart failure and has been associated with worse cardiovascular outcomes. Indeed, exercise training and several heart failure drug categories display favorable effects against endothelial dysfunction apart from their established direct myocardial benefit.

Inactivating the Uninhibited: The Tale of Activins and Inhibins in Pulmonary Arterial Hypertension

Advances in technology and biomedical knowledge have led to the effective diagnosis and treatment of an increasing number of rare diseases. Pulmonary arterial hypertension (PAH) is a rare disorder of the pulmonary vasculature that is associated with high mortality and morbidity rates. Although significant progress has been made in understanding PAH and its diagnosis and treatment, numerous unanswered questions remain regarding pulmonary vascular remodeling, a major factor contributing to the increase in pulmonary arterial pressure. Here, we discuss the role of activins and inhibins, both of which belong to the TGF-β superfamily, in PAH development. We examine how these relate to signaling pathways implicated in PAH pathogenesis. Furthermore, we discuss how activin/inhibin-targeting drugs, particularly sotatercep, affect pathophysiology, as these target the afore-mentioned specific pathway. We highlight activin/inhibin signaling as a critical mediator of PAH development that is to be targeted for therapeutic gain, potentially improving patient outcomes in the future.

lncRNA-TCONS_00008552 expression in patients with pulmonary arterial hypertension due to congenital heart disease

Long noncoding RNAs (lncRNAs) are potential regulators of a variety of cardiovascular diseases. Therefore, there is a series of differentially expressed lncRNAs in pulmonary arterial hypertension (PAH) that may be used as markers to diagnose PAH and even predict the prognosis. However, their specific mechanisms remain largely unknown. Therefore, we investigated the biological role of lncRNAs in patients with PAH. First, we screened patients with PAH secondary to ventricular septal defect (VSD) and those with VSD without PAH to assess differences in lncRNA and mRNA expression between the two groups. Our results revealed the significant upregulation of 813 lncRNAs and 527 mRNAs and significant downregulation of 541 lncRNAs and 268 mRNAs in patients with PAH. Then, we identified 10 hub genes in a constructed protein-protein interaction network. Next, we performed bioinformatics analyses, including Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis and subsequently constructed coding-noncoding co-expression networks. We screened lncRNA-TCONS_00008552 and lncRNA-ENST00000433673 as candidate genes and verified the expression levels of the lncRNAs using quantitative reverse-transcription PCR. Although expression levels of lncRNA-TCONS_00008552 in the plasma from the PAH groups were significantly increased compared with the control groups, there was no significant difference in the expression of lncRNA-ENST00000433673 between the two groups. This study bolsters our understanding of the role of lncRNA in PAH occurrence and development and indicates that lncRNA-TCONS_00008552 is a novel potential molecular marker for PAH.

Pathophysiology and new advances in pulmonary hypertension

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.