Targeting transforming growth factor-β receptors in pulmonary hypertension

Intranasal delivery of R8-modified circNFXL1 liposomes ameliorates Su5416-induced pulmonary arterial hypertension in C57BL/6 mice

BACKGROUND

Pulmonary arterial hypertension (PAH) is a progressive, life-threatening condition characterized by increased pulmonary vascular resistance and right ventricular hypertrophy (RVH). Current treatments primarily alleviate symptoms but do not effectively target the underlying molecular mechanisms driving the disease. This study aimed to evaluate the therapeutic potential of R8-modified liposomal delivery of circNFXL1, a circular RNA, in a mouse model of PAH.

METHODS

R8-circNFXL1 liposomes were synthesized and characterized for their physicochemical properties, including encapsulation efficiency. PAH was induced in C57BL/6 mice using a combination of subcutaneous Su5416 administration and hypoxic exposure. Intranasal delivery of R8-circNFXL1 was performed, and therapeutic effects were assessed using echocardiography and hemodynamic measurements. Molecular mechanisms were explored through analysis of the miR-29b/Kcnb1 axis, a regulatory pathway in PAH.

RESULTS

The R8-circNFXL1 liposomes demonstrated optimal physicochemical properties, including high encapsulation efficiency. Treatment with R8-circNFXL1 significantly reduced RVH, improved cardiac function, and mitigated pulmonary vascular remodeling compared to untreated PAH controls. Molecular analysis revealed that R8-circNFXL1 modulated the miR-29b/Kcnb1 axis, providing insights into its mechanism of action.

CONCLUSIONS

R8-circNFXL1 liposomes offer a promising, targeted therapeutic strategy for PAH by addressing underlying molecular mechanisms. This approach has potential implications for developing alternative treatments to improve disease management and outcomes in PAH.

Genetic screening in cohort of Egyptian patients with pulmonary arterial hypertension disease

BACKGROUND

Variants in the bone morphogenetic protein 2 receptor gene (BMPR2) are the most frequent genetic cause of pulmonary arterial hypertension (PAH). However, correlation of BMPR2 variants and PAH clinical phenotype remains to be elucidated.

METHODS AND RESULTS

The goal of the present study is to investigate variants of the causative gene (BMPR2) in 25 Egyptian patients clinically pre-diagnosed with PAH symptoms and 10 healthy candidates using Sanger sequencing technique. Three pathogenic heterozygous missense variants have been illustrated in BMPR2 gene, two novel variants (V387E, E481K) in exon 9 and 11 respectively and one previously reported missense variant (C496G) in exon 11. The remaining 22 patients as well as the 10 healthy individuals showed no pathogenic variants.

CONCLUSION

Further studies on larger number of participants, using advanced NGS technique, should be performed to enrich information about genotype/phenotype correlations and incidence of PAH disease among Egyptian population; thus, it would provide families of PAH patients with accurate genetic counseling in order to prevent disease recurrence.

Pediatric Pulmonary Hypertension is Associated With Increased Circulating Levels of BMP 7 and CHIP

Pulmonary arterial endothelial and smooth muscle cell homeostasis is regulated through the bone morphogenetic protein (BMP) and transforming growth factor beta (TGF-β) receptor pathways. Pathway imbalance results in pulmonary hypertension (PH). Each pathway has ligands and modulators influencing this balance. How these pathways differ in pediatric PH patients is unknown. Ten PH and 20 control subjects (ages 2-17 years) were prospectively enrolled. Pulmonary artery serum BMP 2, 4, 6, 7, 9, 10, activin A, TGF-β1, carboxyl terminus of Hsc70-interating protein (CHIP), NT Pro BNP, and CRP were measured by ELISA. Analyses were made using the Fisher's exact test, the Mann-Whitney test, ROC analysis, and Pearson and Spearman correlations as appropriate. PH subjects were group 1 (four with simple shunts) or group 3 PH. Control subjects had shunts scheduled for catheter closure but no PH. Only BMP 7 and CHIP levels were statistically elevated in PH patients versus controls; (BMP 7 0.081(0.076-0.084) vs. 0.074(0.069-0.08) OD, p = 0.044), (CHIP 0.17(0.14-0.24) vs. 0.13(0.12-0.15) OD, p = 0.007) respectively. BMP 7 levels correlated with RV systolic pressure (0.431, p = 0.02) and pulmonary resistance (0.446, p = 0.013). CHIP correlated with mean pulmonary artery pressure (0.449, p = 0.013) and resistance ratios (Rp/Rs) (0.419, p = 0.02). BMP 7 OD of 0.077 had sensitivity/specificity of 80% and 70% for PH. CHIP OD of 0.136 had sensitivity/specificity of 90% and 65% for PH. BMP 7 and CHIP levels are heightened in pediatric PH patients which correlate with catheterization values. BMP 7 and CHIP could provide sensitive markers for PH to aid in diagnosis and disease monitoring.

The role of lactate metabolism and lactylation in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a complex and progressive disease characterized by elevated pulmonary artery pressure and vascular remodeling. Recent studies have underscored the pivotal role of metabolic dysregulation and epigenetic modifications in the pathogenesis of PAH. Lactate, a byproduct of glycolysis, is now recognized as a key molecule that links cellular metabolism with activity regulation. Recent findings indicate that, in addition to altered glycolytic activity and dysregulated. Lactate homeostasis and lactylation-a novel epigenetic modification-also play a significant role in the development of PAH. This review synthesizes current knowledge regarding the relationship between altered glycolytic activity and PAH, with a particular focus on the cumulative effects of lactate in pulmonary vascular cells. Furthermore, lactylation, an emerging epigenetic modification, is discussed in the context of PAH. By elucidating the complex interplay between lactate metabolism and lactylation in PAH, this review aims to provide insights into potential therapeutic targets. Understanding these metabolic pathways may lead to innovative strategies for managing PAH and improving patient outcomes. Future research should focus on the underlying mechanisms through which lactylation influences the pathophysiology of PAH, thereby aiding in the development of targeted interventions.

New therapies in pulmonary arterial hypertension: Recent insights

Pulmonary Arterial Hypertension (PAH) is a complex and progressive disease characterized by elevated pulmonary vascular resistance and right heart failure. Current therapies primarily focus on pulmonary vasodilation; however, novel approaches that target the underlying pathophysiological mechanisms-such as TGF-β signalling, epigenetic alterations, growth factors, inflammation, and extracellular matrix remodelling-are promising alternatives for improving treatment outcomes. This is a review of recent advances in the development of innovative therapeutic strategies for PAH. The first section of this paper explores approaches targeting TGF-β signalling, both acting directly on receptors through drugs like Sotatercept and exogenous BMP9, and indirectly, inhibiting the degradation of key receptors, such as BMPR2. Subsequent sections describe treatments that target epigenetic regulators, e.g. poly (ADP-ribose) polymerase-1 (PARP-1) inhibitors and direct BRD4 antagonists, tyrosine kinase inhibitors (Seralutinib), and therapies aimed at inflammation, such as IL-6 inhibitors, CD-20 inhibitors, and monoclonal antibodies that prevent macrophage migration. Finally, strategies that target the serotonin pathway, and other metabolic and hormonal pathways are described. This review includes both preclinical and clinical trial data that support efficacy, safety and the future potential of such therapies. Collectively, these therapeutic approaches can be valuable in treating PAH by targeting multiple aspects of its pathogenesis, potentially resulting in improved clinical outcomes for patients affected by this debilitating, life-limiting condition.

Pulmonary hypertension in patients carrying FLNA loss-of-function variants

BACKGROUND

Pulmonary hypertension (PH) is an unusual complication of X-linked disease caused by loss-of-function (LOF) variants in the filamin A (FLNA) gene. Patients with FLNA LOF may also present dysmorphic facial features, aortic dilation, thrombocytopenia and periventricular nodular heterotopia (PVNH).

METHODS

We reported the clinical, functional, haemodynamic and radiological characteristics of patients with FLNA LOF variants and PH from the French PH Network.

RESULTS

Nine patients were identified with a female:male ratio of 8:1. PH was diagnosed at a median (range) age of 36 (0-69) years. Associated conditions included epilepsy (n=5), PVNH (n=7), valvular heart disease (n=8), congenital heart diseases (n=4), thrombocytopenia (n=4) and hyperlaxity (n=4). Right heart catheterisation confirmed moderate-to-severe pre-capillary PH with a median (range) mean pulmonary arterial pressure of 33 (22-49) mmHg and pulmonary vascular resistance of 4.7 (2.4-8.0) WU. The median (range) diffusing capacity of the lung for carbon monoxide corrected for haemoglobin was markedly decreased (48% (22-64%) of predicted values) and five patients had obstructive ventilatory disorder. High-resolution computed tomography showed heterogeneous parenchyma (n=8), emphysema (n=3), presence of a peripheral hyperclear band (n=3) and aortic ectasia (n=4). Pathological assessment available in one patient revealed significant remodelling of small pulmonary arteries, interstitial oedema and irregular alveoli shapes. During follow-up, three patients died, including two from right heart failure. No patient died from aortic rupture.

CONCLUSIONS

Pre-capillary PH, likely due to multiple mechanisms, may complicate the course of patients with FLNA LOF variants and may be the presenting symptom leading to diagnosis. The combination of PH with parenchymal involvement and extrapulmonary symptoms (epilepsy, congenital heart diseases, valvular and aortic involvement, and thrombocytopenia) should prompt genetic screening for FLNA.

Sotatercept: A First-In-Class Activin Signaling Inhibitor for Pulmonary Arterial Hypertension

Objective: The objective of the study is to review the characteristics, efficacy, safety, and clinical relevance of sotatercept in pulmonary arterial hypertension (PAH). Data Sources: A literature search containing search terms related to sotatercept and PAH was conducted. Embase via Elsevier, MEDLINE via Ovid, the medRxiv preprint server, Cochrane Library CENTRAL trials registry, and ClinicalTrials.gov were searched from inception through October 31, 2024. The package insert was utilized to obtain drug information and additional data. Study Selection and Data Extraction: Phase II-III clinical trials investigating sotatercept for PAH were included. Articles written in English were extracted while animal studies and phase I clinical trials were excluded. Data Synthesis: In patients with WHO Group 1, functional class II-III PAH, adding sotatercept to background therapy increased 6-minute walk distance in phase II-III trials. Pooled analysis from PULSAR (phase II) and STELLAR (phase III) showed improvements in pulmonary vascular resistance and NT-proBNP. Exploratory data from PULSAR revealed that BMPR2 genetic variant status was not associated with significant differences in treatment effects. SPECTRA (phase IIb) demonstrated improved right ventricular structure and function. Interim analysis from SOTERIA showed that treatment effects persist at 1 year. Conclusions: Sotatercept is a viable add-on therapy for patients with PAH Group 1 and functional class II-III. Additional data are needed to assess long-term outcomes among treatment-naïve patients and those with the most severe symptomatology.

Halofuginone prevents inflammation and proliferation of high-altitude pulmonary hypertension by inhibiting the TGF-β1/Smad signaling pathway

The inflammatory response of lung tissue and abnormal proliferation of pulmonary artery smooth muscle cells are involved in the pathogenesis of high-altitude pulmonary hypertension (HAPH). Halofuginone (HF), an active ingredient derivative of Chang Shan (Dichroa febrifuga Lour. [Hydrangeaceae]), has antiproliferative, antihypertrophic, antifibrotic, and other effects, but its protective effects on HAPH remains unclear. In the present study, we evaluated the efficacy of HF on HAPH by establishing a 6000 m HAPH rat model. Male Sprague-Dawley rats were divided into normoxia, normoxia + halofuginone (1 mg/kg), hypoxia, and hypoxia + halofuginone (1 mg/kg) groups. The results showed that HF (1 mg/kg) could prevent hypoxia-induced hemodynamic abnormalities, right ventricular hypertrophy, and pulmonary vascular remodeling in rats. We further detected the expression levels of inflammatory factors interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α) and proliferative/antiproliferative indicators proliferating cell nuclear antigen (PCNA), cyclin-dependent kinase 6 (CDK6), Cyclin D1, p21 in lung tissue, and found that HF could attenuate the lung tissue inflammatory response and proliferative response in HAPH rats. In addition, we also examined the expression levels of transforming growth factor-β1 (TGF-β1), Smad2/3 and p-Smad2/3 in lung tissue, and found that HF exerted therapeutic effects by inhibiting the TGF-β1/Smad signaling pathway.

Sotatercept: A New Era in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by proliferative remodeling and obliterative narrowing of the pulmonary vasculature. While outcomes have improved with existing treatments targeting 3 main pathways, there remains a critical need for novel therapies that address different and novel mechanisms of PAH. Sotatercept, recently Food and Drug Administration (FDA) approved, is a groundbreaking fusion protein that binds to activin and growth differentiation factors, rebalancing antiproliferative and pro-proliferative signals to reverse remodeling in both the pulmonary vasculature and the right ventricle. This review highlights current evidence exploring the safety and efficacy of sotatercept in the 2 landmark trials, phase 2 Pulmonary Arterial Hypertension and Sotatercept Trial and Research and phase 3 Sotatercept Treatment in Expansion of Long-term Learning and Assessment in PAH trial, which were instrumental in securing FDA approval for adult PAH patients with WHO functional class II or III symptoms already receiving background pulmonary hypertension therapy. Overall, sotatercept represents a landmark advancement in PAH treatment, offering hope for patients and the potential to delay or avoid lung transplantation. Importantly, this marks the beginning of an era of targeted therapies aimed at reverse remodeling in PAH while improving outcomes.

MicroRNA in pediatric pulmonary hypertension microRNA profiling to inform disease classification, severity, and treatment response in pediatric pulmonary hypertension

Pediatric pulmonary hypertension is a heterogeneous disease associated with significant morbidity and mortality. MicroRNAs have been implicated as both pathologic drivers of disease and potential therapeutic targets in pediatric pulmonary hypertension. We sought to characterize the circulating microRNA profiles of a diverse array of pediatric patients with pulmonary hypertension using high-throughput sequencing technology. Peripheral blood samples were drawn from patients recruited at the time of a clinically indicated cardiac catheterization, and microRNA sequencing followed by differential expression and target/pathway enrichment analyses were performed. Among 63 pediatric patients with pulmonary hypertension, we identified specific microRNA signatures that uniquely classified patients by disease subtype, correlated with indicators of disease severity including invasive hemodynamic metrics, and changed over the course of treatment for pulmonary hypertension. These microRNA profiles include a number of specific microRNA molecules known to function in signaling pathways critical to pulmonary vascular biology and disease, including transforming growth factor-β (TGF-β), VEGF, PI3K/Akt, cGMP-PKG, and HIF-1 signaling. Circulating levels of miR-122-5p, miR-124-3p, miR-204-5p, and miR-9-5p decreased over the course of treatment in a subset of patients who had multiple samples drawn during the study period. Our findings support the further investigation of specific microRNAs as mechanistic mediators, biomarkers, and therapeutic targets in pulmonary hypertension.NEW & NOTEWORTHY We present novel insight into the circulating microRNA profiles of pediatric patients with pulmonary hypertension. Our findings support the utility of microRNAs as both useful biomarkers of disease severity and potential therapeutic targets in pediatric pulmonary hypertension.

From basic scientific research to the development of new drugs for pulmonary arterial hypertension: insights from activin-targeting agents

Pulmonary arterial hypertension (PAH) is a severe disorder of the pulmonary vasculature leading to right ventricular failure. This pulmonary vascular remodelling leads to increased pulmonary vascular resistance and high pulmonary arterial pressures. Despite the development of new therapies, many patients continue to experience significant morbidity and mortality. This review offers a comprehensive overview of the current understanding of PAH pathophysiology, with a focus on key mechanisms that contribute to pulmonary endothelial cell dysfunction and the pathological accumulation of pulmonary artery smooth muscle cells, mesenchymal cells and inflammatory cells in the walls of remodelled small pulmonary vessels, three processes central to the progression of PAH. In particular, it highlights recent developments in targeting the activin signalling pathway, a novel therapeutic approach that shows promise in modulating these pathological processes. The review also addresses the ongoing challenges in translating preclinical findings into effective clinical treatments, emphasising the importance of integrating human data with preclinical models and adopting innovative strategies to bridge the gap between research and clinical practice.

Identification of hub genes, diagnostic model, and immune infiltration in preeclampsia by integrated bioinformatics analysis and machine learning

PURPOSE

This study aimed to identify novel biomarkers for preeclampsia (PE) diagnosis by integrating Weighted Gene Co-expression Network Analysis (WGCNA) with machine learning techniques.

PATIENTS AND METHODS

We obtained the PE dataset GSE25906 from the gene expression omnibus (GEO) database. Analysis of differentially expressed genes (DEGs) and module genes with Limma and Weighted Gene Co-expression Network analysis (WGCNA). Candidate hub genes for PE were identified using machine learning. Subsequently, we used western-blotting (WB) and real-time fluorescence quantitative (qPCR) to verify the expression of F13A1 and SCCPDH in preeclampsia patients. Finally, we estimated the extent of immune cell infiltration in PE samples by employing the CIBERSORT algorithms.

RESULTS

Our findings revealed that F13A1 and SCCPDH were the hub genes of PE. The nomogram and two candidate hub genes had high diagnostic values (AUC: 0.90 and 0.88, respectively). The expression levels of F13A1 and SCCPDH were verified by WB and qPCR. CIBERSORT analysis confirmed that the PE group had a significantly larger proportion of plasma cells and activated dendritic cells and a lower portion of resting memory CD4 + T cells.

CONCLUSION

The study proposes F13A1 and SCCPDH as potential biomarkers for diagnosing PE and points to an improvement in early detection. Integration of WGCNA with machine learning could enhance biomarker discovery in complex conditions like PE and offer a path toward more precise and reliable diagnostic tools.

Expression and Diagnostic Value of miR-3591-5p in Patients with Congenital Heart Disease-Associated Pulmonary Arterial Hypertension

OBJECTIVES

This study explored the expression and diagnostic value of differentially expressed miR-3591-5p in congenital heart disease-associated pulmonary arterial hypertension (CHD-PAH).

METHODS

A total of 110 CHD patients were divided into four groups based on their mean pulmonary artery pressure (PAPm). The plasma miR-3591-5p expression was determined by reverse transcription polymerase chain reaction. The correlation between the miR-3591-5p expression and various clinical indices, as well as its diagnostic value for CHD-PAH patients, were analyzed.

RESULTS

The plasma levels of miR-3591-5p were significantly higher in the patients in the no PAH group, mild PAH group, and moderate to severe PAH group than in the control group, and they were significantly higher in the moderate to severe PAH group than in the no PAH group. Correlation analysis revealed that the miR-3591-5p expression level was significantly positively correlated with various clinical indicators, including the PAPm, pulmonary artery systolic pressure, brain natriuretic peptide, pulmonary vascular resistance, red blood cell distribution width, uric acid, Na + , systolic blood pressure, left atrial internal dimension, left ventricular end-diastolic dimension, and left ventricular end-systolic dimension. Univariate and multivariate regression analyses identified the plasma miR-3591-5p level as an independent risk factor for CHD-PAH. Receiver operating characteristic curve analysis demonstrated that the plasma miR-3591-5p level had a moderate diagnostic value for CHD-PAH, which was further improved when combined with a B-type natriuretic peptide.

CONCLUSION

This study identified the expression profiles of differentially expressed plasma miRNAs in patients with CHD-PAH, focusing on the upregulation of miR-3591-5p. Bioinformatics analysis suggested that miR-3591-5p is involved in the pathogenesis of CHD-PAH and may serve as a circulating biomarker that may have diagnostic and prognostic value in CHD-PAH.

SGLT2 inhibitors as a potential therapeutic option for pulmonary hypertension: mechanisms and clinical perspectives

Pulmonary arterial hypertension (PAH), one subtype of pulmonary hypertension (PH), is a life-threatening condition characterized by pulmonary arterial remodeling, elevated pulmonary vascular resistance, and blood pressure in the pulmonary arteries, leading to right heart failure and increased mortality. The disease is marked by endothelial dysfunction, vasoconstriction, and vascular remodeling. The role of Sodium-Glucose Co-Transporter-2 (SGLT2) inhibitors, a class of medications originally developed for diabetes management, is increasingly being explored in the context of cardiovascular diseases, including PAH, due to their potential to modulate these pathophysiological processes. In this review, we systematically examine the burgeoning evidence from both basic and clinical studies that describe the effects of SGLT2 inhibitors on cardiovascular health, with a special emphasis on PAH. By delving into the complex interactions between these drugs and the potential pathobiology that underpins PH, this study seeks to uncover the mechanistic underpinnings that could justify the use of SGLT2 inhibitors as a novel therapeutic approach for PAH. We collate findings that illustrate how SGLT2 inhibitors may influence the normal function of pulmonary arteries, possibly alleviating the pathological hallmarks of PAH such as inflammation, oxidative stress, aberrant cellular proliferation, and so on. Our review thereby outlines a potential paradigm shift in PAH management, suggesting that these inhibitors could play a crucial role in modulating the disease's progression by targeting the potential dysfunctions that drive it. This comprehensive synthesis of existing research underscores the imperative need for further clinical trials to validate the efficacy of SGLT2 inhibitors in PAH and to integrate them into the therapeutic agents used against this challenging disease.

Growth differentiation factor 7 alleviates the proliferation and metastasis of hepatocellular carcinoma

Background and aims

Inflammatory factors play significant roles in the development and occurrence of hepatocellular carcinoma (HCC). However, the tumor-protective functions of growth differentiation factors (GDFs) in HCC are yet to be clarified. In this study, we aimed to evaluate the expression levels of 10 GDFs in tumor and paratumor tissues from patients with HCC and perform in vitro and in vivo experiments to elucidate the role of GDF7 in regulating the proliferation and metastasis of HCC.

Methods

The gene expression of 10 GDFs was compared between HCC and paratumors using The Cancer Genome Atlas dataset and patient-derived tissues. A tumor microarray containing 108 HCC tissue samples was used to explore the prognostic value of GDF7 expression. Loss-of-function experiments were also performed in vitro and in vivo to investigate the role of GDF7 in HCC.

Results

The mRNA and protein levels of GDF7 were significantly lower in HCC tumors than in paratumors (P < 0.001). Kaplan-Meier analysis showed that decreased GDF7 expression in HCC was associated with worse overall survival (5-year rate: 61.8% vs. 27.5%, P < 0.001) and increased recurrence risk (P < 0.001). Multivariate Cox regression analysis demonstrated that low GDF7 expression, the presence of microvascular invasion, and elevated alpha-fetoprotein (AFP) levels were independent risk factors for tumor recurrence and poor survival. Downregulation of GDF7 also increased the tumor growth in HCC cells and in an HCC xenograft model. GDF7 knockdown promoted migration and invasion via epithelial-mesenchymal transition. Meanwhile, a negative correlation between JunB proto-oncogene (JUNB) and GDF7 was observed in HCC tissues. Modulating JUNB levels altered GDF7 protein expression.

Conclusions

GDF7 is a potential biomarker for predicting superior outcomes in patients with HCC. GDF7 amplification is a potential therapeutic option for HCC.

Pulmonary arterial hypertension: Navigating the pathways of progress in diagnosis, treatment, and patient care

Pulmonary arterial hypertension (PAH) is a form of precapillary pulmonary hypertension caused by a complex process of endothelial dysfunction and vascular remodeling. If left untreated, this progressive disease presents with symptoms of incapacitating fatigue causing marked loss of quality of life, eventually culminating in right ventricular failure and death. Patient management is complex and based on accurate diagnosis, risk stratification, and treatment initiation, with close monitoring of response and disease progression. Understanding the underlying pathophysiology has enabled the development of multiple drugs directed at different targets in the pathological chain. Vasodilator therapy has been the mainstay approach for the last few years, significantly improving quality of life, functional status, and survival. Recent advances in therapies targeting dysfunctional pathways beyond endothelial dysfunction may address the fundamental processes underlying the disease, raising the prospect of increasingly effective options for this high-risk group of patients with a historically poor prognosis.

A Belgian consensus on sotatercept for the treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare disease affecting the small pulmonary vessels, ultimately leading to right ventricular failure and death. Current treatment options target three different pathways (endothelin, nitric oxide/cGMP and prostacyclin pathways). Despite their demonstrated efficacy, these therapies (commonly used in combination) do not cure the disease which is why novel pathways beyond the traditional 'big three' are being developed. Sotatercept is a ligand trap for multiple proteins within the TGF-β superfamily that was recently approved in the US for the treatment of PAH. Unlike currently available therapies, sotatercept has the potential to act as an anti-remodelling agent rather than a vasodilator. The safety and efficacy of subcutaneous (SC) sotatercept have been established in two multicentre, placebo-controlled randomised-controlled trials. The compound has been shown to consistently improve a variety of measurable endpoints, including exercise capacity, haemodynamics, quality of life and delay of clinical worsening. The drug appears to have an acceptable safety profile, although it is associated with an increased risk in developing telangiectasia and biological changes affecting platelet counts and haemoglobin. This study reviews the current evidence on SC sotatercept and provides a Belgian perspective on its place in the future treatment strategy for PAH.

Pulmonary Arterial Hypertension and TGF-β Superfamily Signaling: Focus on Sotatercept

Pulmonary arterial hypertension (PAH) is a rare and progressive disease that continues to remain highly morbid despite multiple advances in medical therapies. There remains a persistent and desperate need to identify novel methods of treating and, ideally, reversing the pathologic vasculopathy that results in PAH development and progression. Sotatercept is a first-in-class fusion protein that is believed to primarily inhibit activin signaling resulting in decreased cell proliferation and differentiation, though the exact mechanism remains uncertain. Here, we review the currently available PAH therapies, data highlighting the importance of transforming growth factor-β (TGF-β) superfamily signaling in the development of PAH, and the published and on-going clinical trials evaluating sotatercept in the treatment of PAH. We will also discuss preclinical data supporting the potential use of the fusion protein KER-012 in the inhibition of aberrant TGF-β superfamily signaling to ameliorate the obstructive vasculopathy of PAH.

Evidence and unresolved questions in pulmonary hypertension: Insights from the 5th French Pulmonary Hypertension Network Meeting

Pulmonary hypertension (PH) continues to present significant challenges to the medical community, both in terms of diagnosis and treatment. The advent of the updated 2022 European Society of Cardiology (ESC) and European Respiratory Society (ERS) guidelines has introduced pivotal changes that reflect the rapidly advancing understanding of this complex disease. These changes include a revised definition of PH, updates to the classification system, and treatment algorithm. While these guidelines offer a critical framework for the management of PH, they have also sparked new discussions and questions. The 5th French Pulmonary Hypertension Network Meeting (Le Kremlin-Bicêtre, France, 2023), addressed these emergent questions and fostering a deeper understanding of the disease's multifaceted nature. These discussions were not limited to theoretical advancements but extended into the practical realms of patient management, highlighting the challenges and opportunities in applying the latest guidelines to clinical practice.

Effect of sotatercept on circulating proteomics in pulmonary arterial hypertension

Alterations in specific signalling pathways within the bone morphogenetic protein/transforming growth factor-β (BMP/TGF-β) family, involving several precisely regulated activator or inhibitor ligands, have been identified as pathogenic drivers of pulmonary arterial hypertension (PAH). These alterations, particularly affecting BMPRII and activin-dependent pathways, have led to innovative therapies, notably the development of sotatercept [1, 2]. Sotatercept, a fusion protein of the extracellular domain of human ACTRIIA and the Fc domain of human IgG1, has shown promising results in improving key clinical, functional, and haemodynamic parameters in PAH patients, as evidenced by positive results in the phase 2 PULSAR and phase 3 STELLAR trials [3, 4]. This progress was partly based on preclinical studies showing that reducing activin-induced Smad2/3 phosphorylation levels, by suppressing activin production in mice [5] or using soluble receptors in rats [6, 7], can attenuate pulmonary vascular remodelling. Despite these advancements, the precise mechanisms of action of these approaches in humans and rodents need to be better understood to enhance these valuable tools. Sotatercept raises several critical questions regarding its mechanism of action, and a deeper understanding could reveal the pathophysiological mechanisms of PAH, leading to more effective therapeutic approaches.

Proteomic analysis of circulating biomarkers reveals that sotatercept's impact extends beyond activins to influence BMP-9 and BMP-10, along with essential metabolic and inflammatory factors https://bit.ly/3Z5AZJ3

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.

Advances in the potential of nebulized inhalation for the treatment of pulmonary arterial hypertension

Pulmonary hypertension is a pathophysiologic manifestation of a heterogeneous group of diseases, with the main pathophysiologic mechanisms being persistent pulmonary vasoconstriction and irreversible vascular remodeling. The impact significantly affects the prognosis of patients with pulmonary hypertension. If it is not treated and intervened in time, it may lead to right ventricular failure and further endanger the patient's life. Within the past decade or so, nebulized inhalation therapy is considered to have advantages in the treatment of pulmonary hypertension as a safe, limited, and rapid therapy, for example, inhaled vasodilators (prostate analogs, nitroglycerin, carbon monoxide analogs sildenafil, and nitroprusside), inhaled anti-inflammatory and antiproliferative agents (simvastatin, and selatinib), and inhaled peroxides (levocetirizine) have been recognized as emerging therapeutic approaches in the treatment of pulmonary hypertension as emerging therapeutic approaches. Therefore, this article provides a brief review of recent advances in the potential of nebulized inhaled vasodilators, anti-inflammatory and antiproliferative agents, and anti-peroxides for the treatment of pulmonary hypertension, with the aim of providing different therapeutic options for the treatment of pulmonary hypertension, enhancing the quality of survival, alleviating symptoms, and improving the prognosis of patients with this condition.

Comprehensive time-course gene expression evaluation of high-risk beef cattle to establish immunological characteristics associated with undifferentiated bovine respiratory disease

Bovine respiratory disease (BRD) remains the leading infectious disease in beef cattle production systems. Host gene expression upon facility arrival may indicate risk of BRD development and severity. However, a time-course approach would better define how BRD development influences immunological and inflammatory responses after disease occurrences. Here, we evaluated whole blood transcriptomes of high-risk beef cattle at three time points to elucidate BRD-associated host response. Sequenced jugular whole blood mRNA from 36 cattle (2015: n = 9; 2017: n = 27) across three time points (n = 100 samples; days [D]0, D28, and D63) were processed through ARS-UCD1.2 reference-guided assembly (HISAT2/Stringtie2). Samples were categorized into BRD-severity cohorts (Healthy, n = 14; Treated 1, n = 11; Treated 2+, n = 11) via frequency of antimicrobial clinical treatment. Assessment of gene expression patterns over time within each BRD cohort was modeled through an autoregressive hidden Markov model (EBSeq-HMM; posterior probability ≥ 0.5, FDR < 0.01). Mixed-effects negative binomial models (glmmSeq; FDR < 0.05) and edgeR (FDR < 0.10) identified differentially expressed genes between and across cohorts overtime. A total of 2,580, 2,216, and 2,381 genes were dynamically expressed across time in Healthy, Treated 1, and Treated 2+ cattle, respectively. Genes involved in the production of specialized resolving mediators (SPMs) decreased at D28 and then increased by D63 across all three cohorts. Accordingly, SPM production and alternative complement were differentially expressed between Healthy and Treated 2+ at D0, but not statistically different between the three groups by D63. Magnitude, but not directionality, of gene expression related to SPM production, alternative complement, and innate immune response signified Healthy and Treated 2+ cattle. Differences in gene expression at D63 across the three groups were related to oxygen binding and carrier activity, natural killer cell-mediated cytotoxicity, cathelicidin production, and neutrophil degranulation, possibly indicating prolonged airway pathology and inflammation weeks after clinical treatment for BRD. These findings indicate genomic mechanisms indicative of BRD development and severity over time.

Muscular hyperplasia in Crohn's disease strictures: through thick and thin

Fibrostenosing Crohn's disease (CD) represents a challenging clinical condition characterized by the development of symptomatic strictures within the gastrointestinal tract. Despite therapeutic advancements in managing inflammation, the progression of fibrostenotic complications remains a significant concern, often necessitating surgical intervention. Recent investigations have unveiled the pivotal role of smooth muscle cell hyperplasia in driving luminal narrowing and clinical symptomatology. Drawing parallels to analogous inflammatory conditions affecting other organs, such as the airways and blood vessels, sheds light on common underlying mechanisms of muscular hyperplasia. This review synthesizes current evidence to elucidate the mechanisms underlying smooth muscle cell proliferation in CD-associated strictures, offering insights into potential therapeutic targets. By highlighting the emerging significance of muscle thickening as a novel therapeutic target, this review aims to inform future research endeavors and clinical strategies with the goal to mitigate the burden of fibrostenotic complications in CD and other conditions.

Disrupted BMP-9 Signaling Impairs Pulmonary Vascular Integrity in Hepatopulmonary Syndrome

Rationale: Hepatopulmonary syndrome (HPS) is a severe complication of liver diseases characterized by abnormal dilation of pulmonary vessels, resulting in impaired oxygenation. Recent research highlights the pivotal role of liver-produced BMP-9 (bone morphogenetic protein-9) in maintaining pulmonary vascular integrity. Objectives: This study aimed to investigate the involvement of BMP-9 in human and experimental HPS. Methods: Circulating BMP-9 levels were measured in 63 healthy control subjects and 203 patients with cirrhosis with or without HPS. Two animal models of portal hypertension were employed: common bile duct ligation with cirrhosis and long-term partial portal vein ligation without cirrhosis. Additionally, the therapeutic effect of low-dose BMP activator FK506 was investigated, and the pulmonary vascular phenotype of BMP-9-knockout rats was analyzed. Measurements and Main Results: Patients with HPS related to compensated cirrhosis exhibited lower levels of circulating BMP-9 compared with patients without HPS. Patients with severe cirrhosis exhibited consistently low levels of BMP-9. HPS characteristics were observed in animal models, including intrapulmonary vascular dilations and an increase in the alveolar-arterial gradient. HPS development in both rat models correlated with reduced intrahepatic BMP-9 expression, decreased circulating BMP-9 level and activity, and impaired pulmonary BMP-9 endothelial pathway. Daily treatment with FK506 for 2 weeks restored the BMP pathway in the lungs, alleviating intrapulmonary vascular dilations and improving gas exchange impairment. Furthermore, BMP-9-knockout rats displayed a pulmonary HPS phenotype, supporting its role in disease progression. Conclusions: The study findings suggest that portal hypertension-induced loss of BMP-9 signaling contributes to HPS development.

Genetic background of pulmonary (vascular) diseases - how much is written in the codes?

PURPOSE OF REVIEW

To provide a comprehensive overview of the underlying genetic defects of pulmonary (vascular) diseases and novel treatment avenues.

RECENT FINDINGS

Pulmonary arterial hypertension (PAH) is the prime example of a pulmonary vascular disease, which can be caused by genetic mutations in some patients. Germline mutations in the BMPR2 gene and further genes lead to vessel remodelling, increase of pulmonary vascular resistance and onset of heritable PAH. The PAH genes with the highest evidence and strategies for genetic testing and counselling have been assessed and evaluated in 2023 by international expert consortia. Moreover, first treatment options have just arisen targeting the molecular basis of PAH.

SUMMARY

Apart from PAH, this review touches on the underlying genetic causes of further lung diseases including alpha 1 antitrypsin deficiency, cystic fibrosis, familial pulmonary fibrosis and lymphangioleiomyomatosis. We point out the main disease genes, the underlying pathomechanisms and novel therapies trying not only to relieve symptoms but to treat the molecular causes of the diseases.

PAI-1 deficiency drives pulmonary vascular smooth muscle remodeling and pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by vasoconstriction and remodeling of small pulmonary arteries (PAs). Central to the remodeling process is a switch of pulmonary vascular cells to a proliferative, apoptosis-resistant phenotype. Plasminogen activator inhibitors-1 and -2 (PAI-1 and PAI-2) are the primary physiological inhibitors of urokinase-type and tissue-type plasminogen activators (uPA and tPA), but their roles in PAH are unsettled. Here, we report that: 1) PAI-1, but not PAI-2, is deficient in remodeled small PAs and in early-passage PA smooth muscle and endothelial cells (PASMCs and PAECs) from subjects with PAH compared with controls; 2) PAI-1-/- mice spontaneously develop pulmonary vascular remodeling associated with upregulation of mTORC1 signaling, pulmonary hypertension (PH), and right ventricle (RV) hypertrophy; and 3) pharmacological inhibition of uPA in human PAH PASMCs suppresses proproliferative mTORC1 and SMAD3 signaling, restores PAI-1 levels, reduces proliferation, and induces apoptosis in vitro, and prevents the development of SU5416/hypoxia-induced PH and RV hypertrophy in vivo in mice. These data strongly suggest that downregulation of PAI-1 in small PAs promotes vascular remodeling and PH due to unopposed activation of uPA and consequent upregulation of mTOR and transforming growth factor-β (TGF-β) signaling in PASMCs, and call for further studies to determine the potential benefits of targeting the PAI-1/uPA imbalance to attenuate and/or reverse pulmonary vascular remodeling and PH.NEW & NOTEWORTHY This study identifies a novel role for the deficiency of plasminogen activator inhibitor (PAI)-1 and resultant unrestricted uPA activity in PASMC remodeling and PH in vitro and in vivo, provides novel mechanistic link from PAI-1 loss through uPA-induced Akt/mTOR and TGFβ-Smad3 upregulation to pulmonary vascular remodeling in PH, and suggests that inhibition of uPA to rebalance the uPA-PAI-1 tandem might provide a novel approach to complement current therapies used to mitigate this pulmonary vascular disease.

Valvular Endocarditis and Biventricular Heart Failure in the Setting of Tropheryma whipplei Disease

Whipple disease is a rare systemic illness associated with weight loss, diarrhea, and arthralgia. Asymptomatic carriage is common, but the disease can be complicated by cardiac involvement and may result in culture-negative endocarditis. Cardiac manifestations of the disease can lead to death. This report presents the case of a 66-year-old man with Whipple disease and biventricular heart failure with cardiogenic shock. Medical therapy followed by successful replacement of the aortic and mitral valves resulted in substantial improvement.

Post-treatment with Resolvin D1 attenuates pulmonary hypertension by inhibiting endothelial-to-mesenchymal transition

Pulmonary hypertension (PH) is a life-threatening disease characterized by pulmonary vascular remodeling. Endothelial-to-mesenchymal transition (EndMT) is an important manifestation and mechanism of pulmonary vascular remodeling. Resolvin D1 (RvD1) is an endogenous lipid mediator promoting the resolution of inflammation. However, the role of RvD1 on EndMT in PH remains unknown. Here, we aimed to investigate the effect and mechanisms of RvD1 on the treatment of PH. We showed that RvD1 and its receptor FPR2 expression were markedly decreased in PH patients and both chronic hypoxia-induced PH (CH-PH) and sugen 5416/hypoxia-induced PH (SuHx-PH) mice models. RvD1 treatment decreased right ventricular systolic pressure (RVSP) and alleviated right ventricular function, and reduced pulmonary vascular remodeling and collagen deposition in the perivascular of both two PH mice models. Then, RvD1 inhibited EndMT in both the lungs of PH mice models and primary cultured human umbilical vein endothelial cells (HUVECs) treated with TGF-β and IL-1β. Moreover, RvD1 inhibited EndMT by downregulating Smad2/3 phosphorylation in vivo and in vitro via FPR2. In conclusion, our date suggest that RvD1/FPR2 axis prevent experimental PH by inhibiting endothelial-mensenchymal-transition and may be a therapeutic target for PH.

Digital Spatial Profiling Identifies Distinct Molecular Signatures of Vascular Lesions in Pulmonary Arterial Hypertension

Rationale: Idiopathic pulmonary arterial hypertension (IPAH) is characterized by extensive pulmonary vascular remodeling caused by plexiform and obliterative lesions, media hypertrophy, inflammatory cell infiltration, and alterations of the adventitia. Objective: We sought to test the hypothesis that microscopic IPAH vascular lesions express unique molecular profiles, which collectively are different from control pulmonary arteries. Methods: We used digital spatial transcriptomics to profile the genomewide differential transcriptomic signature of key pathological lesions (plexiform, obliterative, intima+media hypertrophy, and adventitia) in IPAH lungs (n = 11) and compared these data with the intima+media hypertrophy and adventitia of control pulmonary artery (n = 5). Measurements and Main Results: We detected 8,273 transcripts in the IPAH lesions and control lung pulmonary arteries. Plexiform lesions and IPAH adventitia exhibited the greatest number of differentially expressed genes when compared with intima+media hypertrophy and obliterative lesions. Plexiform lesions in IPAH showed enrichment for 1) genes associated with transforming growth factor β signaling and 2) mutated genes affecting the extracellular matrix and endothelial-mesenchymal transformation. Plexiform lesions and IPAH adventitia showed upregulation of genes involved in immune and IFN signaling, coagulation, and complement pathways. Cellular deconvolution indicated variability in the number of vascular and inflammatory cells between IPAH lesions, which underlies the differential transcript profiling. Conclusions: IPAH lesions express unique molecular transcript profiles enriched for pathways involving pathogenetic pathways, including genetic disease drivers, innate and acquired immunity, hypoxia sensing, and angiogenesis signaling. These data provide a rich molecular-structural framework in IPAH vascular lesions that inform novel biomarkers and therapeutic targets in this highly morbid disease.

Immunotherapy for Pulmonary Arterial Hypertension: From the Pathogenesis to Clinical Management

Pulmonary hypertension (PH) is a progressive cardiovascular disease, which may lead to severe cardiopulmonary dysfunction. As one of the main PH disease groups, pulmonary artery hypertension (PAH) is characterized by pulmonary vascular remodeling and right ventricular dysfunction. Increased pulmonary artery resistance consequently causes right heart failure, which is the major reason for morbidity and mortality in this disease. Although various treatment strategies have been available, the poor clinical prognosis of patients with PAH reminds us that further studies of the pathological mechanism of PAH are still needed. Inflammation has been elucidated as relevant to the initiation and progression of PAH, and plays a crucial and functional role in vascular remodeling. Many immune cells and cytokines have been demonstrated to be involved in the pulmonary vascular lesions in PAH patients, with the activation of downstream signaling pathways related to inflammation. Consistently, this influence has been found to correlate with the progression and clinical outcome of PAH, indicating that immunity and inflammation may have significant potential in PAH therapy. Therefore, we reviewed the pathogenesis of inflammation and immunity in PAH development, focusing on the potential targets and clinical application of anti-inflammatory and immunosuppressive therapy.

Comparative Effectiveness of Sotatercept and Approved Add-On Pulmonary Arterial Hypertension Therapies: A Systematic Review and Network Meta-Analysis

Background: There are no direct comparisons of sotatercept to add-on therapies approved for pulmonary arterial hypertension (PAH). Objective: This study aimed to compare the efficacy and safety of add-on sotatercept versus other add-on therapies using a network meta-analysis. Data Sources: We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and clinicaltrials.gov until April 15, 2023, for randomized trials involving patients with PAH who were treated with add-on sotatercept or other add-on PAH therapies. Data Extraction: Data extraction and risk-of-bias assessments were performed independently and in duplicate using the Cochrane RoB 2.0 tool. We performed a frequentist random-effects network meta-analysis using the restricted maximum-likelihood estimator and assessed the certainty of evidence using the GRADE (grading of recommendations assessment development, and evaluation) approach. Synthesis: Our search found 18 trials (5,777 patients) eligible for analysis. Sotatercept reduces clinical worsening as compared with placebo (relative risk [RR], 0.21; 95% confidence interval [CI] = 0.11-0.41; with high certainty). Sotatercept probably reduces clinical worsening more, compared with add-on endothelin receptor antagonists (RR, 0.28; 95% CI = 0.14-0.55), inhaled prostanoid (RR, 40.21; 95% CI = 0.07-0.67), and prostanoid taken orally (RR, 0.32; 95% CI = 0.16-0.67; all with moderate certainty). Sotatercept probably improves 6-minute-walk distance compared with placebo (mean difference [MD], 36.89 m; 95% CI = 25.26-48.51). Although sotatercept probably improves 6-minute-walk distance more than add-on endothelin receptor antagonists (MD, 18.38 m; 95% CI = 5.92-30.84) and prostanoid taken orally (MD, 25.66 m; 95% CI = 13.71-37.61), it did not exceed the minimal clinically important difference of 33 m (both with moderate certainty). Conclusions: Sotatercept is an effective add-on therapy for PAH, likely superior to many approved add-on PAH therapies in reducing clinical worsening.

BRCC3 Regulation of ALK2 in Vascular Smooth Muscle Cells: Implication in Pulmonary Hypertension

BACKGROUND

An imbalance of antiproliferative BMP (bone morphogenetic protein) signaling and proliferative TGF-β (transforming growth factor-β) signaling is implicated in the development of pulmonary arterial hypertension (PAH). The posttranslational modification (eg, phosphorylation and ubiquitination) of TGF-β family receptors, including BMPR2 (bone morphogenetic protein type 2 receptor)/ALK2 (activin receptor-like kinase-2) and TGF-βR2/R1, and receptor-regulated Smads significantly affects their activity and thus regulates the target cell fate. BRCC3 modifies the activity and stability of its substrate proteins through K63-dependent deubiquitination. By modulating the posttranslational modifications of the BMP/TGF-β-PPARγ pathway, BRCC3 may play a role in pulmonary vascular remodeling, hence the pathogenesis of PAH.

METHODS

Bioinformatic analyses were used to explore the mechanism by which BRCC3 deubiquitinates ALK2. Cultured pulmonary artery smooth muscle cells (PASMCs), mouse models, and specimens from patients with idiopathic PAH were used to investigate the rebalance between BMP and TGF-β signaling in regulating ALK2 phosphorylation and ubiquitination in the context of pulmonary hypertension.

RESULTS

BRCC3 was significantly downregulated in PASMCs from patients with PAH and animals with experimental pulmonary hypertension. BRCC3, by de-ubiquitinating ALK2 at Lys-472 and Lys-475, activated receptor-regulated Smad1/5/9, which resulted in transcriptional activation of BMP-regulated PPARγ, p53, and Id1. Overexpression of BRCC3 also attenuated TGF-β signaling by downregulating TGF-β expression and inhibiting phosphorylation of Smad3. Experiments in vitro indicated that overexpression of BRCC3 or the de-ubiquitin-mimetic ALK2-K472/475R attenuated PASMC proliferation and migration and enhanced PASMC apoptosis. In SM22α-BRCC3-Tg mice, pulmonary hypertension was ameliorated because of activation of the ALK2-Smad1/5-PPARγ axis in PASMCs. In contrast, Brcc3-/- mice showed increased susceptibility of experimental pulmonary hypertension because of inhibition of the ALK2-Smad1/5 signaling.

CONCLUSIONS

These results suggest a pivotal role of BRCC3 in sustaining pulmonary vascular homeostasis by maintaining the integrity of the BMP signaling (ie, the ALK2-Smad1/5-PPARγ axis) while suppressing TGF-β signaling in PASMCs. Such rebalance of BMP/TGF-β pathways is translationally important for PAH alleviation.

Pirfenidone and nintedanib attenuates pulmonary artery endothelial and smooth muscle cells transformations induced by IL-11

Idiopathic pulmonary fibrosis (IPF) associated to pulmonary hypertension (PH) portends a poor prognosis, characterized by lung parenchyma fibrosis and pulmonary artery remodeling. Serum and parenchyma levels of Interleukin 11 (IL-11) are elevated in IPF-PH patients and contributes to pulmonary artery remodeling and PH. However, the effect of current approved therapies against IPF in pulmonary artery remodeling induced by IL-11 is unknown. The aim of this study is to analyze the effects of nintedanib and pirfenidone on pulmonary artery endothelial and smooth muscle cell remodeling induced by IL-11 in vitro. Our results show that nintedanib (NTD) and pirfenidone (PFD) ameliorates endothelial to mesenchymal transition (EnMT), pulmonary artery smooth muscle cell to myofibroblast-like transformation and pulmonary remodeling in precision lung cut slices. This study provided also evidence of the inhibitory effect of PFD and NTD on IL-11-induced endothelial and muscle cells proliferation and senescence. The inhibitory effect of these drugs on monocyte arrest and angiogenesis was also studied. Finally, we observed that IL-11 induced canonical signal transducer and activator of transcription 3 (STAT3) and non-canonical mitogen-activated protein kinase 1/2 (ERK1/2) phosphorylation, but, PFD and NTD only inhibited ERK1/2 phosphorylation. Therefore, this study provided evidence of the inhibitory effect of NTD and PFD on markers of pulmonary artery remodeling induced by IL-11.

Recent developments in connective tissue disease associated pulmonary arterial hypertension

Connective tissue disease associated pulmonary arterial hypertension (CTD-PAH) has benefited from the major treatment advances that have occurred within pulmonary hypertension over the past three decades. Inclusion of CTD-PAH cases in pivotal clinical trials led to regulatory approval and drug availability. This has improved outcomes but there are additional challenges for management. First, the multifaceted co-morbidity related to the associated CTD needs treatment alongside PAH and may impact on diagnosis and evaluation of treatment response. Secondary, cardiac involvement, interstitial lung disease and predisposition to thromboembolism in CTD may lead to compound phenotypes where PH has multiple mechanisms as well as precapillary pulmonary vasculopathy of PAH. In general, especially for systemic sclerosis, CTD-PAH has worse long-term survival than idiopathic or familial PAH. However, CTD also present an opportunity for screening and early detection and treatment for associated PAH, and this may in the future be a major advantage over idiopathic disease where presentation inevitable only occurs at symptomatic stages and diagnosis may be delayed. This article reviews and summarises some of the recent developments in investigation and management of CTD-PAH.

NKX2-5 regulates vessel remodeling in scleroderma-associated pulmonary arterial hypertension

NKX2-5 is a member of the homeobox-containing transcription factors critical in regulating tissue differentiation in development. Here, we report a role for NKX2-5 in vascular smooth muscle cell phenotypic modulation in vitro and in vascular remodeling in vivo. NKX2-5 is upregulated in scleroderma patients with pulmonary arterial hypertension. Suppression of NKX2-5 expression in smooth muscle cells halted vascular smooth muscle proliferation and migration, enhanced contractility, and blocked the expression of extracellular matrix genes. Conversely, overexpression of NKX2-5 suppressed the expression of contractile genes (ACTA2, TAGLN, CNN1) and enhanced the expression of matrix genes (COL1) in vascular smooth muscle cells. In vivo, conditional deletion of NKX2-5 attenuated blood vessel remodeling and halted the progression to hypertension in a mouse chronic hypoxia model. This study revealed that signals related to injury such as serum and low confluence, which induce NKX2-5 expression in cultured cells, is potentiated by TGF-β and further enhanced by hypoxia. The effect of TGF-β was sensitive to ERK5 and PI3K inhibition. Our data suggest a pivotal role for NKX2-5 in the phenotypic modulation of smooth muscle cells during pathological vascular remodeling and provide proof of concept for therapeutic targeting of NKX2-5 in vasculopathies.

Pathophysiological basis of hepatopulmonary syndrome

Circulatory changes with increased blood flow and vasodilatation/vasoconstriction imbalance are an integral consequence of liver cirrhosis and portal hypertension and can affect the pulmonary circulation with the development of vascular disorders, with hepatopulmonary syndrome (HPS) being the most common. HPS is a serious pulmonary complication of progressive liver disease, resulting in a poor clinical prognosis. Vascular tone decrease, monocytic infiltration of pulmonary vessels, formation of intrapulmonary arteriovenous shunts, dysfunction of alveolar type II cells, destruction of the endothelial glycocalyx are important in the pathogenesis of HPS. Abnormalities of pulmonary capillaries lead to hypoxemia caused by a violation of the ventilation/perfusion ratio, diffusion disorders, and the development of arteriovenous anastomoses. Infiltration of the pulmonary vessels by monocytes is one of the key factors of HPS. This migration is facilitated by the intestinal microbiota translocation into the portal bloodstream with increased expression of proinflammatory cytokines (tumor necrosis factor α, interleu­kins 1, 6), leading to the activation of monocytes. Monocytes located in the pulmonary circulation promote the vasodilation through the activation of inducible nitric oxide (NO) synthase and thus NO production. This is also associated with endothelial dysfunction due to a decreased hepatic secretion of bone morphogenetic protein 9 and increased endothelin 1, endothelial overexpression of endothelin B receptors, and increased endothelial NO production. Proangiogenic factors such as vascular endothelial growth factor, platelet-derived growth factor, and placental growth factor play an important role in the proliferation of pulmonary capillaries. Circulation of tumor necrosis factor α, bile acids and monocyte infiltration in the pulmonary circulation lead to increased apoptosis of alveolar type II cells and decreased surfactant synthesis. Chronic inflammation in HPS disrupts the continuity of the endothelial glycocalyx layer. This article provides an overview of the current knowledge on the pathogenesis of HPS, summarizes many features of the disease based on the literature research in MEDLINE database on the PubMed platform.

B-cells in pulmonary arterial hypertension: friend, foe or bystander?

There is an unmet need for new therapeutic strategies that target alternative pathways to improve the prognosis of patients with pulmonary arterial hypertension (PAH). As immunity has been involved in the development and progression of vascular lesions in PAH, we review the potential contribution of B-cells in its pathogenesis and evaluate the relevance of B-cell-targeted therapies. Circulating B-cell homeostasis is altered in PAH patients, with total B-cell lymphopenia, abnormal subset distribution (expansion of naïve and antibody-secreting cells, reduction of memory B-cells) and chronic activation. B-cells are recruited to the lungs through local chemokine secretion, and activated by several mechanisms: 1) interaction with lung vascular autoantigens through cognate B-cell receptors; 2) costimulatory signals provided by T follicular helper cells (interleukin (IL)-21), type 2 T helper cells and mast cells (IL-4, IL-6 and IL-13); and 3) increased survival signals provided by B-cell activating factor pathways. This activity results in the formation of germinal centres within perivascular tertiary lymphoid organs and in the local production of pathogenic autoantibodies that target the pulmonary vasculature and vascular stabilisation factors (including angiotensin-II/endothelin-1 receptors and bone morphogenetic protein receptors). B-cells also mediate their effects through enhanced production of pro-inflammatory cytokines, reduced anti-inflammatory properties by regulatory B-cells, immunoglobulin (Ig)G-induced complement activation, and IgE-induced mast cell activation. Precision-medicine approaches targeting B-cell immunity are a promising direction for select PAH conditions, as suggested by the efficacy of anti-CD20 therapy in experimental models and a trial of rituximab in systemic sclerosis-associated PAH.

The Impact of Immunogenicity on the Pharmacokinetics, Efficacy, and Safety of Sotatercept in a Phase III Study of Pulmonary Arterial Hypertension

Sotatercept, a soluble fusion protein comprising the extracellular domain of activin receptor type IIA linked to the Fc portion of human IgG1, is a first-in-class activin signaling inhibitor under development for the treatment of pulmonary arterial hypertension (PAH). We evaluated antidrug antibody (ADA) development and determined the effects of immunogenicity on the pharmacokinetics (PKs), efficacy, and safety of sotatercept in STELLAR, a multicenter, double-blind phase III trial (NCT04576988) wherein participants with PAH were randomized 1:1 to receive sotatercept (starting dose 0.3; target dose 0.7 mg/kg) or placebo subcutaneously every 3 weeks in combination with background therapies for ≤ 72 weeks. ADA-positive (ADA-POS) participants were identified and characterized for neutralizing antibodies (NAbs). PKs, efficacy, and safety were evaluated by ADA and NAb status. Of 162 evaluable participants, 42 (25.9%) were ADA-POS through week 24, of whom 11 (6.8%) were also NAb-POS. Median onset of ADAs was 3.29 weeks (interquartile range (IQR): 3.14-6.14), and median duration was 6 weeks (IQR: 3.14-17.86). No clinically meaningful differences were found across subgroups that were ADA-NEG, ADA-POS/NAb-NEG, and ADA-POS/NAb-POS, in terms of PKs (sotatercept trough concentration over time, mean postdose trough concentration at the end of treatment, and clearance), efficacy (changes from baseline in 6-minute walk distance, pulmonary vascular resistance, and N-terminal pro-B-type natriuretic peptide levels), and safety (incidence of hypersensitivity, anaphylactic reactions, and administration site reactions). We conclude that ADA incidence from sotatercept treatment was 25.9% and did not meaningfully affect the PKs, efficacy, or safety of sotatercept in participants with PAH.

Hemodynamic and Clinical Profiles of Pulmonary Arterial Hypertension Patients with GDF2 and BMPR2 Variants

Asians have a higher carrier rate of pulmonary arterial hypertension (PAH)-related genetic variants than Caucasians do. This study aimed to identify PAH-related genetic variants using whole exome sequencing (WES) in Asian idiopathic and heritable PAH cohorts. A WES library was constructed, and candidate variants were further validated by polymerase chain reaction and Sanger sequencing in the PAH cohort. In a total of 69 patients, the highest incidence of variants was found in the BMPR2, ATP13A3, and GDF2 genes. Regarding the BMPR2 gene variants, there were two nonsense variants (c.994C>T, p. Arg332*; c.1750C>T, p. Arg584*), one missense variant (c.1478C>T, p. Thr493Ile), and one novel in-frame deletion variant (c.877_888del, p. Leu293_Ser296del). Regarding the GDF2 variants, there was one likely pathogenic nonsense variant (c.259C>T, p. Gln87*) and two missense variants (c.1207G>A, p. Val403Ile; c.38T>C, p. Leu13Pro). The BMPR2 and GDF2 variant subgroups had worse hemodynamics. Moreover, the GDF2 variant patients were younger and had a significantly lower GDF2 value (135.6 ± 36.2 pg/mL, p = 0.002) in comparison to the value in the non-BMPR2/non-GDF2 mutant group (267.8 ± 185.8 pg/mL). The BMPR2 variant carriers had worse hemodynamics compared to the patients with the non-BMPR2/non-GDF2 mutant group. Moreover, there was a significantly lower GDF2 value in the GDF2 variant carriers compared to the control group. GDF2 may be a protective or corrected modifier in certain genetic backgrounds.

Endothelial periostin regulates vascular remodeling by promoting endothelial dysfunction in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by vascular remodeling associated with extracellular matrix (ECM) deposition, vascular cell hyperproliferation, and neointima formation in the small pulmonary artery. Endothelial dysfunction is considered a key feature in the initiation of vascular remodeling. Although vasodilators have been used for the treatment of PAH, it remains a life-threatening disease. Therefore, it is necessary to identify novel therapeutic targets for PAH treatment. Periostin (POSTN) is a secretory ECM protein involved in physiological and pathological processes, such as tissue remodeling, cell adhesion, migration, and proliferation. Although POSTN has been proposed as a potential target for PAH treatment, its role in endothelial cells has not been fully elucidated. Here, we demonstrated that POSTN upregulation correlates with PAH by analyzing a public microarray conducted on the lung tissues of patients with PAH and biological experimental results from in vivo and in vitro models. Moreover, POSTN overexpression leads to ECM deposition and endothelial abnormalities such as migration. We found that PAH-associated endothelial dysfunction is mediated at least in part by the interaction between POSTN and integrin-linked protein kinase (ILK), followed by activation of nuclear factor-κB signaling. Silencing POSTN or ILK decreases PAH-related stimuli-induced ECM accumulation and attenuates endothelial abnormalities. In conclusion, our study suggests that POSTN serves as a critical regulator of PAH by regulating vascular remodeling, and targeting its role as a potential therapeutic strategy for PAH.

Treating Pulmonary Arterial Hypertension With Sotatercept: A Meta-Analysis

Pulmonary arterial hypertension (PAH) results from proliferative remodeling and narrowing of the pulmonary vasculature. Sotatercept is a first-in-class fusion protein that has recently garnered attention for showing improvements in patients with PAH. This meta-analysis of randomized controlled trials (RCTs) assesses the overall efficacy of Sotatercept in treating PAH. PubMed, Google Scholar, and Clinicaltrials.gov were searched using relevant keywords and MeSH terms. Studies were included if RCTs compared Sotatercept with placebo in patients with PAH. Our comprehensive literature search yielded 3,127 results, of which two RCTs with 429 patients were included in this meta-analysis. The patients were on background therapy for PAH. Results of the meta-analysis show that when compared with placebo, Sotatercept improved the six-minute walk distance (mean difference [MD] 34.99; 95% confidence interval [CI] 19.02-50.95; P < 0.0001), the World Health Organization (WHO) functional class (odds ratio [OR] 2.50; 95% CI 1.50-4.15; P = 0.0004), and pulmonary vascular resistance (PVR, MD -253.90; 95% CI -356.05 to -151.75; P < 0.00001). However, reduction in N-terminal pro-B-type natriuretic peptide (NT-proBNP, MD -1563.14; 95% CI -3271.93 to 145.65; P = 0.07) was not statistically significant in the Sotatercept group versus placebo. In conclusion, Sotatercept improves the six-minute walk distance, WHO functional class, and PVR in patients with PAH receiving background therapy. However, the effect on NT-proBNP levels was not statistically significant. More research is needed to assess the clinical relevance of these findings.

A Systematic Review of Novel Therapies of Pulmonary Arterial Hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is a progressive, cureless disease, characterized by increased pulmonary vascular resistance and remodeling, with subsequent ventricular dilatation and failure. New therapeutic targets are being investigated for their potential roles in improving PAH patients' symptoms and reversing pulmonary vascular pathology.

METHOD

We aimed to address the available knowledge from the published randomized controlled trials (RCTs) regarding the role of Rho-kinase (ROCK) inhibitors, bone morphogenetic protein 2 (BMP2) inhibitors, estrogen inhibitors, and AMP-activated protein kinase (AMPK) activators on the PAH evaluation parameters. This systematic review (SR) was registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (CDR42022340658) and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Overall, 5092 records were screened from different database and registries; 8 RCTs that met our inclusion criteria were included. The marked difference in the study designs and the variability of the selected outcome measurement tools among the studies made performing a meta-analysis impossible. However, the main findings of this SR relate to the powerful potential of the AMPK activator and the imminent antidiabetic drug metformin, and the BMP2 inhibitor sotatercept as promising PAH-modifying therapies. There is a need for long-term studies to evaluate the effect of the ROCK inhibitor fasudil and the estrogen aromatase inhibitor anastrozole in PAH patients. The role of tacrolimus in PAH is questionable. The discrepancy in the hemodynamic and clinical parameters necessitates defining cut values to predict improvement. The differences in the PAH etiologies render the judgment of the therapeutic potential of the tested drugs challenging.

CONCLUSION

Metformin and sotatercept appear as promising therapeutic drugs for PAH.

CLINICAL TRIALS REGISTRATION

This work was registered in PROSPERO (CDR42022340658).

Case report: Pathological differences in pulmonary arterial hypertension in long-term responders to calcium channel blockers

Background

This study investigates the pulmonary arterial histopathology in patients with idiopathic pulmonary arterial hypertension (IPAH) and acute vasoreactive phenotype, who demonstrated long-term survival (>30 years) and incidental death from causes other than PAH progression. The pathological changes observed in these patients were compared with those in patients with bone morphogenetic protein receptor type 2 (BMPR2) mutation.

Case Presentation

We present two cases of patients with pulmonary arterial hypertension (PAH) who died incidentally from causes unrelated to PAH progression. We report compares pulmonary arterial histopathology in long-term survivors of CCB-responsive PAH patient and a hereditary PAH patient with a BMPR2 mutation. Lung specimens were analyzed using the Heath and Edwards (HE) classification and percentage muscular wall thickness (%MWT) of pulmonary arterioles. A significant difference in the severity of grading (p = 0.0001) and distribution between grades 1-2, 4 (p = 0.001), and 5 (p = 0.014) was observed between both patients. These findings suggest differential vascular pathology between the two cases, with CCB responders displaying more mild illness lesions compared to BMPR2 mutant patients.

Conclusion

The study revealed that CCB responders exhibit more mild illness vascular lesions than BMPR2 mutant patients despite their long-term survival, suggesting a difference in vascular pathology between the two phenotypes.

Targeting IL-11 system as a treatment of pulmonary arterial hypertension

IL-11 is linked to fibrotic diseases, but its role in pulmonary hypertension is unclear. We examined IL-11's involvement in idiopathic pulmonary arterial hypertension (iPAH). Using samples from control (n = 20) and iPAH (n = 6) subjects, we assessed IL-11 and IL-11Rα expression and localization through RT-qPCR, ELISA, immunohistochemistry, and immunofluorescence. A monocrotaline-induced PAH model helped evaluate the impact of siRNA-IL-11 on pulmonary artery remodeling and PH. The effects of recombinant human IL-11 and IL-11Rα on human pulmonary artery smooth muscle cell (HPASMC) proliferation, pulmonary artery endothelial cell (HPAEC) mesenchymal transition, monocyte interactions, endothelial tube formation, and precision cut lung slice (PCLS) pulmonary artery remodeling and contraction were evaluated. IL-11 and IL-11Rα were over-expressed in pulmonary arteries (3.2-fold and 75-fold respectively) and serum (1.5-fold and 2-fold respectively) of patients with iPAH. Therapeutic transient transfection with siRNA targeting IL-11 resulted in a significant reduction in pulmonary artery remodeling (by 98%), right heart hypertrophy (by 66%), and pulmonary hypertension (by 58%) in rats exposed to monocrotaline treatment. rhIL-11 and soluble rhIL-11Rα induce HPASMC proliferation and HPAEC to monocyte interactions, mesenchymal transition, and tube formation. Neutralizing monoclonal IL-11 and IL-11Rα antibodies inhibited TGFβ1 and EDN-1 induced HPAEC to mesenchymal transition and HPASMC proliferation. In 3D PCLS, rhIL-11 and soluble rhIL-11Rα do not promote pulmonary artery contraction but sensitize PCLS pulmonary artery contraction induced by EDN-1. In summary, IL-11 and IL-11Rα are more highly expressed in the pulmonary arteries of iPAH patients and contribute to pulmonary artery remodeling and the development of PH.