Treatment Of Pulmonary Arterial Hypertension Research Articles

Is sotatercept, which traps activins and growth differentiation factors, a new dawn in treating pulmonary arterial hypertension (PAH)?

ABSTRACT Introduction Although the prevalence of pulmonary arterial hypertension (PAH) is low, mortality is high. In PAH, there is a down-regulation of the bone morphogenetic protein receptor type 2 pathway, leading to a prominence of the upregulation pathway that is mediated by activins and growth differentiation factors acting at the receptor type IIA (ActRIIA). Sotatercept is an ActRIIA fusion protein. STELLAR was a phase 3 study of sotatercept for the treatment of PAH. Areas covered STELLAR. The primary endpoint of STELLAR was change from baseline at 24 weeks in the 6-minute walking distance, which was increased by 34.4 m by sotatercept compared to 1 m in the placebo group. Epistaxis/nosebleed, telangiectasia, and dizziness were more common with sotatercept than placebo. Expert opinion By targeting the remodeling in PAH, sotatercept is providing a new approach to the treatment of PAH and has the potential to slow or reverse cardiovascular remodeling in other conditions, e.g. left heart failure. However, the development of sotatercept for the treatment of PAH still requires a consideration of the appropriate dose and a longer-term assessment of the benefits and safety. If sotatercept becomes available for self-administration, it will be of interest to assess whether this affects adherence and benefits.

The novel KV7 channel activator URO-K10 exerts enhanced pulmonary vascular effects independent of the KCNE4 regulatory subunit

KV7 channels exert a pivotal role regulating vascular tone in several vascular beds. In this context, KV7 channel agonists represent an attractive strategy for the treatment of pulmonary arterial hypertension (PAH). Therefore, in this study, we have explored the pulmonary vascular effects of the novel KV7 channel agonist URO-K10. Consequently, the vasodilator and electrophysiological effects of URO-K10 were tested in rat and human pulmonary arteries (PA) and PA smooth muscle cells (PASMC) using myography and patch-clamp techniques. Protein expression was also determined by Western blot. Morpholino-induced knockdown of KCNE4 was assessed in isolated PA. PASMC proliferation was measured by BrdU incorporation assay. In summary, our data show that URO-K10 is a more effective relaxant of PA than the classical KV7 activators retigabine and flupirtine. URO-K10 enhanced KV currents in PASMC and its electrophysiological and relaxant effects were inhibited by the KV7 channel blocker XE991. The effects of URO-K10 were confirmed in human PA. URO-K10 also exhibited antiproliferative effects in human PASMC. Unlike retigabine and flupirtine, URO-K10-induced pulmonary vasodilation was not affected by morpholino-induced knockdown of the KCNE4 regulatory subunit. Noteworthy, the pulmonary vasodilator efficacy of this compound was considerably increased under conditions mimicking the ionic remodelling (as an in vitro model of PAH) and in PA from monocrotaline-induced pulmonary hypertensive rats. Taking all together, URO-K10 behaves as a KCNE4-independent KV7 channel activator with much increased pulmonary vascular effects compared to classical KV7 channel activators. Our study identifies a promising new drug in the context of PAH.

MicroRNA and lncRNA as the Future of Pulmonary Arterial Hypertension Treatment.

Pulmonary hypertension (PH) is characterized by a progressive increase in pulmonary arterial pressure and pulmonary vascular resistance. In a short time, it leads to right ventricular failure and, consequently, to death. The most common causes of PH include left heart disease and lung disease. Despite the significant development of medicine and related sciences observed in recent years, we still suffer from a lack of effective treatment that would significantly influence the prognosis and prolong life expectancy of patients with PH. One type of PH is pulmonary arterial hypertension (PAH). The pathophysiology of PAH is based on increased cell proliferation and resistance to apoptosis in the small pulmonary arteries, leading to pulmonary vascular remodeling. However, studies conducted in recent years have shown that epigenetic changes may also lie behind the pathogenesis of PAH. Epigenetics is the study of changes in gene expression that are not related to changes in the sequence of nucleotides in DNA. In addition to DNA methylation or histone modification, epigenetic research focuses on non-coding RNAs, which include microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Preliminary research results give hope that targeting epigenetic regulators may lead to new, potential therapeutic possibilities in the treatment of PAH.

HMGB1-induced activation of ER stress contributes to pulmonary artery hypertension in vitro and in vivo

BackgroundHMGB1 and ER stress have been considered to participate in the progression of pulmonary artery hypertension (PAH). However, the molecular mechanism underlying HMGB1 and ER stress in PAH remains unclear. This study aims to explore whether HMGB1 induces pulmonary artery smooth muscle cells (PASMCs) functions and pulmonary artery remodeling through ER stress activation.MethodsPrimary cultured PASMCs and monocrotaline (MCT)-induced PAH rats were applied in this study. Cell proliferation and migration were determined by CCK-8, EdU and transwell assay. Western blotting was conducted to detect the protein levels of protein kinase RNA-like endoplasmic reticulum kinase (PERK), activating transcription factor-4 (ATF4), seven in absentia homolog 2 (SIAH2) and homeodomain interacting protein kinase 2 (HIPK2). Hemodynamic measurements, immunohistochemistry staining, hematoxylin and eosin staining were used to evaluate the development of PAH. The ultrastructure of ER was observed by transmission electron microscopy.ResultsIn primary cultured PASMCs, HMGB1 reduced HIPK2 expression through upregulation of ER stress-related proteins (PERK and ATF4) and subsequently increased SIAH2 expression, which ultimately led to PASMC proliferation and migration. In MCT-induced PAH rats, interfering with HMGB1 by glycyrrhizin, suppression of ER stress by 4-phenylbutyric acid or targeting SIAH2 by vitamin K3 attenuated the development of PAH. Additionally, tetramethylpyrazine (TMP), as a component of traditional Chinese herbal medicine, reversed hemodynamic deterioration and vascular remodeling by targeting PERK/ATF4/SIAH2/HIPK2 axis.ConclusionsThe present study provides a novel insight to understand the pathogenesis of PAH and suggests that targeting HMGB1/PERK/ATF4/SIAH2/HIPK2 cascade might have potential therapeutic value for the prevention and treatment of PAH.

Pulmonary arterial hypertension trials put to the test: Using the fragility index to assess trials robustness

BackgroundRandomized clinical trials (RCTs) are considered the gold standard for evidence-based medicine. The Fragility Index (FI) is a tool to assess the robustness of RCT results. FI was validated for dichotomous outcomes and recent work expanded its use to continuous outcomes. Studying the robustness of RCTs in Pulmonary Arterial Hypertension (PAH) treatments is crucial due to the severity and mortality risks associated with this rare condition. ObjectivesAnalyze FI and Fragility quotient (FQ) of significant primary outcomes in PAH RCTs and study FI correlation with sample size and journal impact factor. MethodsFI and FQ calculation followed by Spearman correlation to assess the correlation between FI and sample size, and FI and impact factor. ResultsThe median sample size of the 21 trials was 202 patients (IQR 106–267), with 6 trials reporting primary outcomes as dichotomous and 15 reporting continuous primary outcomes. The median FI was 10 (IQR 3–20), and the median FQ was 0.044 (0.026–0.097). A moderate correlation was found between FI and sample size, with r = 0.56; P = 0.008 and FI and journal impact factor (r=0.50; P=0.019). The FI for continuous outcomes was similar to that for dichotomous outcomes. ConclusionsThis study represents the first analysis of the FI and FQ of PAH treatment RCTs, and expands the use of FI to continuous outcomes in this context. The moderate correlation between FI and sample size suggests that increasing sample size alone is partially correlated to a higher FI. The similarity between FI for continuous and dichotomous outcomes supports the broader use of FI in PAH RCTs.

Bioinformatics Analysis of the Regulatory lncRNA–miRNA–mRNA Network and Drug Prediction in Patients with Pulmonary Arterial Hypertension

Objective: Pulmonary arterial hypertension (PAH) is a cardiovascular disease caused by primary proliferative lesions in pulmonary arterioles. Competing endogenous RNAs (ceRNAs) have been reported to act as sponges for microRNAs (miRNAs). To date, however, the mechanisms underlying ceRNA involvement in PAH have not been investigated. This study aimed to construct a PAH-related ceRNA network to further explore the mechanisms of PAH. Methods: A probe reannotation was conducted to identify the long non-coding RNAs (lncRNAs) and messenger RNAs (mRNAs) involved in PAH. Based on the reannotation results, the “limma” package was used to identify the differentially expressed genes (DEGs) and lncRNAs. The miRcode database was used to predict the lncRNA–miRNA interactions. Then, the mRNAs targeted by the miRNAs were predicted by using TargetScan, miRTarBase, and miRDB. Based on the above interactions, a ceRNA network was constructed, which was mapped and visualized with Cytoscape 3.6.1 software. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed using the database. To predict possible drugs or molecules that may mitigate PAH, C-Map analysis was applied to find relevant molecular compounds that can reverse the expression of DEGs in cell lines. Results: The ceRNA network consisted of 174 nodes and 304 links, which included 10 lncRNAs, 23 miRNAs, and 53 mRNAs. The hub genes of the ceRNA network for PAH included hsa-miR-17-5p, hsa-miR-20b-5p, MEG3, HCP5, hsa-miR-27a-3p, hsa-miR-107, hsa-miR-142-3p, hsa-miR-363-3p, hsa-miR-301b-3p, and hsa-miR-23b-3p. Calprotectin, irinotecan, and medrysone were found to be the 3 significant compounds. Conclusion: This study found that hsa-miR-17-5p, hsa-miR-20b-5p, MEG3, HCP5, hsa-miR-27a-3p, hsa-miR-107, hsa-miR-142-3p, hsa-miR-363-3p, hsa-miR-301b-3p, and hsa-miR-23b-3p maybe the underlying biomarkers and targets for diagnosis and treatment of PAH.

Inhibition of PCSK9 Improves the Development of Pulmonary Arterial Hypertension Via Down-Regulating Notch3 Expression.

Pulmonary arterial hypertension (PAH) is a fatal disease characterized by continuous constriction and occlusion of small pulmonary arteries, leading to the development of right ventricular failure and death. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a kind of serine protease enzyme that increases low-density lipoprotein cholesterol (LDLC) levels through degrading low-density lipoprotein cholesterol receptors (LDLr). However, whether inhibition of PCSK9 can alleviate PAH has not been reported. We reported that PCSK9 expression was up-regulated in lung tissues of PAH patients. In addition, we used PCSK9 monoclonal antibody subcutaneously to inhibit PCSK9 expression in mice exposed to chronic hypoxia (10%) in combination with SU5416, a VEGF receptor inhibitor. Hypoxia plus SU5416-induced PAH was attenuated in PCSK9 monoclonal antibody-treated mice compared with wild-type mice. PCSK9 inhibited pulmonary vascular remodeling in mice. Moreover, PCSK9 knockdown significantly altered the proliferation and migration of hypoxia-induced PASMCs. We also found that PCSK9 monoclonal antibody inhibited Notch3 expression in vivo and in vitro. Our results suggest that the PCSK9-Notch3 signaling pathway is critical for the proliferation and migration of PASMCs and provides a potential drug target for the treatment of PAH.

Medical Management of Pulmonary Arterial Hypertension: Current Approaches and Investigational Drugs.

Pulmonary arterial hypertension (PAH) is a malignant pulmonary vascular syndrome characterized by a progressive increase in pulmonary vascular resistance and pulmonary arterial pressure, which eventually leads to right heart failure and even death. Although the exact mechanism of PAH is not fully understood, pulmonary vasoconstriction, vascular remodeling, immune and inflammatory responses, and thrombosis are thought to be involved in the development and progression of PAH. In the era of non-targeted agents, PAH had a very dismal prognosis with a median survival time of only 2.8 years. With the deep understanding of the pathophysiological mechanism of PAH as well as advances in drug research, PAH-specific therapeutic drugs have developed rapidly in the past 30 years, but they primarily focus on the three classical signaling pathways, namely the endothelin pathway, nitric oxide pathway, and prostacyclin pathway. These drugs dramatically improved pulmonary hemodynamics, cardiac function, exercise tolerance, quality of life, and prognosis in PAH patients, but could only reduce pulmonary arterial pressure and right ventricular afterload to a limited extent. Current targeted agents delay the progression of PAH but cannot fundamentally reverse pulmonary vascular remodeling. Through unremitting efforts, new therapeutic drugs such as sotatercept have emerged, injecting new vitality into this field. This review comprehensively summarizes the general treatments for PAH, including inotropes and vasopressors, diuretics, anticoagulants, general vasodilators, and anemia management. Additionally, this review elaborates the pharmacological properties and recent research progress of twelve specific drugs targeting three classical signaling pathways, as well as dual-, sequential triple-, and initial triple-therapy strategies based on the aforementioned targeted agents. More crucially, the search for novel therapeutic targets for PAH has never stopped, with great progress in recent years, and this review outlines the potential PAH therapeutic agents currently in the exploratory stage to provide new directions for the treatment of PAH and improve the long-term prognosis of PAH patients.

Surrogate endpoints in pulmonary arterial hypertension trials

Why don't you just look at the pulmonary artery pressure? This question is frequently asked when we discuss endpoints in pulmonary arterial hypertension (PAH) trials with colleagues from other disease areas. Trials of antihypertensive drugs simply look at blood pressure changes, whereas pivotal trials in PAH use change in 6-min walk distance or time to clinical worsening as primary outcome measures. Why the difference? It is not just the invasiveness of right heart catheterisation but much more a question of validated surrogate endpoints. The US Food and Drug Administration (FDA) and other regulatory agencies approve drugs when they improve how patients feel, function, or survive. 1 Temple R Are surrogate markers adequate to assess cardiovascular disease drugs?. JAMA. 1999; 282: 790-795 Crossref PubMed Scopus (298) Google Scholar In systemic hypertension, lowering blood pressure predicts reductions in major adverse cardiovascular events including stroke, myocardial infarction, and cardiovascular death, and so authorities accept blood pressure reduction as a surrogate endpoint—ie, a substitute for a clinically meaningful endpoint that is expected to predict the effect of a therapy. 1 Temple R Are surrogate markers adequate to assess cardiovascular disease drugs?. JAMA. 1999; 282: 790-795 Crossref PubMed Scopus (298) Google Scholar In PAH, there is no convincing evidence that reductions in pulmonary artery pressure or pulmonary vascular resistance are directly linked to improved exercise capacity or better survival. Hence, change in 6-min walk distance is being frequently used as a primary endpoint assessing the function part of the FDA paradigm. Time to clinical worsening has been applied as well, a composite endpoint based on death, PAH-related worsening, and prespecified reductions in exercise capacity. However, these endpoints have limitations. Improvement in 6-min walk distance reflects better exercise capacity but is no surrogate of better outcomes. 2 Gabler NB French B Strom BL et al. Validation of 6-minute walk distance as a surrogate end point in pulmonary arterial hypertension trials. Circulation. 2012; 126: 349-356 Crossref PubMed Scopus (185) Google Scholar Time to clinical worsening does not capture clinical improvement, and reducing clinical worsening events does not necessarily lead to better survival. 3 Sitbon O Channick R Chin KM et al. Selexipag for the treatment of pulmonary arterial hypertension. N Engl J Med. 2015; 373: 2522-2533 Crossref PubMed Scopus (607) Google Scholar , 4 Galiè N Barberà JA Frost AE et al. Initial use of ambrisentan plus tadalafil in pulmonary arterial hypertension. N Engl J Med. 2015; 373: 834-844 Crossref PubMed Scopus (750) Google Scholar , 5 Pulido T Adzerikho I Channick RN et al. Macitentan and morbidity and mortality in pulmonary arterial hypertension. N Engl J Med. 2013; 369: 809-818 Crossref PubMed Scopus (981) Google Scholar In addition, studies designed to show improvement in time to clinical worsening require large sample sizes, a challenge in a rare disease like PAH. Hence, there is an ongoing search for surrogate endpoints. Is low-risk status a surrogate outcome in pulmonary arterial hypertension? An analysis of three randomised trialsMulticomponent risk scores have utility for the prediction of outcomes in patients with PAH. Clinical surrogacy for long-term outcomes cannot be inferred from observational studies of outcomes. Our analyses of three PAH trials with long-term follow-up suggest that further study is necessary before using these or other scores as surrogate outcomes in PAH RCTs or clinical care. Full-Text PDF

Is low-risk status a surrogate outcome in pulmonary arterial hypertension? An analysis of three randomised trials

Targeting short-term improvements in multicomponent risk scores for mortality in patients with pulmonary arterial hypertension (PAH) could result in improved long-term outcomes. We aimed to determine whether PAH risk scores were adequate surrogates for clinical worsening or mortality outcomes in PAH randomised clinical trials (RCTs). We performed an individual participant data meta-analysis of RCTs selected from PAH trials provided by the US Food and Drug Administration (FDA). We calculated predicted risk using the COMPERA, COMPERA 2.0, non-invasive FPHR, REVEAL 2.0, and REVEAL Lite 2 risk scores. The primary outcome of interest was time to clinical worsening, a composite endpoint composed of any of the following events: all-cause death, hospitalisation for worsening PAH, lung transplantation, atrial septostomy, discontinuation of study treatment (or study withdrawal) for worsening PAH, initiation of parenteral prostacyclin analogue therapy, or decrease of at least 15% in 6-min walk distance from baseline, combined with either worsening of WHO functional class from baseline or the addition of an approved PAH treatment. The secondary outcome of interest was time to all-cause mortality. We assessed the surrogacy of these risk scores, parameterised as attainment of low-risk status by 16 weeks, for improvement in long-term clinical worsening and survival using mediation and meta-analysis frameworks. Of 28 trials received from the FDA, three RCTs (AMBITION, GRIPHON, and SERAPHIN; n=2508) had the data necessary to assess long-term surrogacy. The mean age was 49 years (SD 16), 1956 (78%) participants were women, 1704 (68%) were classified as White, and 280 (11%) were Hispanic or Latino. 1388 (55%) of 2503 participants with available data had idiopathic PAH and 776 (31%) of 2503 had PAH associated with connective tissue disease. In a mediation analysis, the proportions of treatment effects explained by attainment of low-risk status ranged only from 7% to 13%. In a meta-analysis of trial-regions, the treatment effects on low-risk status were not predictive of the treatment effects on time to clinical worsening (R2 values 0·01-0·19) nor the treatment effects on time to all-cause mortality (R2 values 0-0·2). A leave-one-out analysis suggested that the use of these risk scores as surrogates might lead to biased inferences regarding the effect of therapies on clinical outcomes in PAH RCTs. Results were similar when using absolute risk scores at 16 weeks as the potential surrogates. Multicomponent risk scores have utility for the prediction of outcomes in patients with PAH. Clinical surrogacy for long-term outcomes cannot be inferred from observational studies of outcomes. Our analyses of three PAH trials with long-term follow-up suggest that further study is necessary before using these or other scores as surrogate outcomes in PAH RCTs or clinical care. Cardiovascular Medical Research and Education Fund, US National Institutes of Health.

Ligustrazine alleviates pulmonary arterial hypertension in rats by promoting the formation of myocardin transcription complex in the nucleus of pulmonary artery smooth muscle cells.

Pulmonary arterial hypertension (PAH) is a pathophysiological state of abnormally elevated pulmonary arterial pressure caused by drugs, inflammation, toxins, viruses, hypoxia, and other risk factors. We studied the therapeutic effect and target of tetramethylpyrazine (tetramethylpyrazine [TMP]; ligustrazine) in the treatment of PAH and we speculated that dramatic changes in myocardin levels can significantly affect the progression of PAH. In vivo, the results showed that administration of TMP significantly prolonged the survival of PAH rats by reducing the proliferative lesions, right ventricular systolic pressure (RVSP), mean pulmonary arterial pressure (mPAP), and the Fulton index in the heart and lung of PAH rats. In vitro, TMP can regulate the levels of smooth muscle protein 22-alpha (SM22-α), and myocardin as well as intracellular cytokines such as NO, transforming growth factor beta (TGF-β), and connective tissue growth factor (CTGF) in a dose-dependent manner (25, 50, or 100 μM). Transfection of myocardin small interfering RNA (siRNA) aggravated the proliferation of pulmonary artery smooth muscle cells (PSMCs), and the regulatory effect of TMP on α-smooth muscle actin (α-SMA) and osteopontin (OPN) disappeared. The application of 10 nM estrogen receptor alpha (ERα) inhibitor MPP promoted the proliferation of PSMCs, but it does not affect the inhibition of TMP on PSMCs proliferation. Finally, we found that TMP promoted the nucleation of myocardin-related transcription factor-A (MRTF-A) and combined it with myocardin. In conclusion, TMP can inhibit the transformation of PSMCs from the contractile phenotype to the proliferative phenotype by promoting the formation of the nuclear (MRTF-A/myocardin) transcription complex to treat PAH.

Evaluating the effectiveness of an apelin analog as a potential treatment for pulmonary arterial hypertension using a sugen-hypoxia rat model

Background: Pulmonary arterial hypertension (PAH) is a debilitating syndrome characterized by heightened pulmonary arterial pressures, and adverse pulmonary vascular remodeling. Eventually, the right ventricle (RV) decompensates, and fatal right heart failure ensues. Existing treatments for PAH are ineffective at improving survival. Apelin is an endogenous cardioprotective peptide, and disruption of apelin signaling was associated with the development of PAH. Restoring the activity of the apelin pathway is a promising approach in reversing the arteriopathy underlying PAH to protect the RV. The salutary actions of apelin are limited by its short half-life; recently, apelin analogs designed with extended half-lives offer a novel therapeutic avenue requiring further testing. Objective: Our project aims to evaluate the effectiveness of an apelin analog as a potential treatment for PAH using a Sugen-Hypoxia (SuHx) rat model of PAH which recapitulates disease characteristics seen in humans. We hypothesize that the apelin analog treatment will improve pulmonary hemodynamics and preserve RV adaptation in rats exposed to SuHx and assuage the pulmonary arteriopathy seen in PAH rats. Experimental design: Male Sprague Dawley rats aged 9 weeks were randomly split into a placebo or treated PAH group. For 3 weeks, a control group was kept within normal room air while the placebo and treated PAH rats were kept in a hypoxia chamber (10% O 2 ). Placebo and treated rats were injected with SU5416 (20 mg/kg, SQ) once at the start of the 3 weeks to induce disease. The normoxic period lasted 5 weeks following the 3 weeks of hypoxia. Treated rats received apelin analog (0.5 μmol/kg, IV, b.i.d.) for the final 3 weeks of normoxia; the placebo group received the same dose of saline. Results: At endpoint, glomerular filtration rate (GFR) measurements showed that placebo treated (PAH-P) PAH rats had reduced GFR while apelin treated (PAH-A) PAH rats had recovered GFR. Echocardiography revealed that PAH-A rats had improved cardiac function compared to PAH-P rats. RV Pressure-volume loop surgeries showed that PAH-A rats had ameliorated RV hemodynamic pressures in contrast to PAH-P rats. Histological analysis demonstrated reduced cardiac fibrosis and hypertrophy, and fewer formations of pulmonary vascular lesions within PAH-A rats compared to PAH-P rats. Single nucleus RNA sequencing performed on RV and lung tissue delineated mitigation of disease progression within the PAH-A group compared to PAH-P rats. Electrocardiography recordings showed more severe electrical remodeling in the PAH-P group compared to the PAH-A rats. Conclusions & significance: Rats with PAH treated with apelin had overall improved cardiopulmonary health outcomes compared to placebo treated PAH rats. The results of this study provide insight into the beneficial role of the apelin pathway in the setting of PAH to propose a new treatment for patients with PAH to improve their duration and quality of life. Canadian Institutes of Health Research Grant This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

C-17 | Efficacy of Pulmonary Artery Denervation Therapy for the Treatment of Pulmonary Artery Hypertension

C-17 | Efficacy of Pulmonary Artery Denervation Therapy for the Treatment of Pulmonary Artery Hypertension

Pulmonary vascular disease as a complication of pediatric congenital heart diseases.

Congenital and acquired heart diseases can cause pulmonary hypertension (PH) in children, either by increasing pulmonary blood flow (PBF), left atrial pressure (LAp), and/or pulmonary vascular resistance (PVR). Pathophysiological process of pulmonary vascular disease (PVD) in different types of congenital heart diseases (CHDs) are reviewed hereafter. As with other types of PH, a rigorous diagnostic evaluation is mandatory to characterize the etiology of the PH, rule out other or additional causes of PH, and establish a risk profile. Cardiac catheterization remains the gold standard exam for PH diagnosis. Treatment of pulmonary arterial hypertension (PAH) associated with CHD (PAH-CHD) can then be started according to the recent guidelines recommendations, although most of the evidence is extrapolated from studies on other causes of PAH. PH in pediatric heart disease is often multifactorial, and sometimes unclassifiable, making the management of these patients complicated. The operability of patients with a prevalent left-to-right shunt and increase of PVR, the management of children with PH associated with left-sided heart disease, the challenges of pulmonary vascular disorders in children with univentricular heart physiology and the role of vasodilator therapy in failing Fontan patients are some of the hot topics discussed in this review.

Silencing EIF3A ameliorates pulmonary arterial hypertension through HDAC1 and PTEN/PI3K/AKT pathway in vitro and in vivo.

Pulmonary vascular remodeling caused by the excessive proliferation of pulmonary arterial smooth muscle cells (PASMCs) is the hallmark feature of pulmonary arterial hypertension (PAH). Eukaryotic initiation factor 3 subunit A (EIF3A) exhibited proliferative activity in multiple cell types. The present study investigated the role of EIF3A in the progression of PAH. A monocrotaline (MCT)-induced PAH rat model was constructed, and adeno-associated virus type 1 (AAV1) carrying EIF3A shRNA was intratracheally delivered to PAH rats to block EIF3A expression. PASMCs were isolated from rats and treated with PDGF-BB to simulate PASMC proliferation, and shRNA for EIF3 was conducted to investigate the mechanism behind the role of EIF3A in PASMC function in vitro. EIF3A expression was upregulated in pulmonary arteries, and EIF3A inhibition effectively improved pulmonary hypertension and right ventricular hypertrophy and suppressed MCT-induced vascular remodeling in vivo. In addition, we found that genetic knockdown of EIF3A reduced PDGF-triggered proliferation and arrested cell cycle, accompanied by downregulated proliferation-related protein expression in PASMCs. Mechanistically, the histone deacetylase 1 (HDAC1)-mediated PTEN/PI3K/AKT pathway was recognized as a primary mechanism in PAH progression. Silencing EIF3A decreased HDAC1 expression, and further inhibited the excessive proliferation of PASMCs by increasing the phosphatase and tension homolog (PTEN) expression and suppressing the AKT phosphorylation. Notably, HDAC1 expression reversed the effect of silencing EIF3A on PAH and PTEN/PI3K/AKT pathway. Collectively, silencing EIF3A improved PAH by decreasing PASMC proliferation through the HDAC1-mediated PTEN/PI3K/AKT pathway. These findings suggest that targeting EIF3A may represent a potential approach for the treatment of PAH.

Design and fabrication of a microfluidic system with embedded circular channels for rotary cell culture.

The development of functional blood vessels is today a fundamental pillar in the evaluation of new therapies and diagnostic agents. This article describes the manufacture and subsequent functionalization, by means of cell culture, of a microfluidic device with a circular section. Its purpose is to simulate a blood vessel in order to test new treatments for pulmonary arterial hypertension. The manufacture was carried out using a process in which a wire with a circular section determines the dimensions of the channel. To fabricate the blood vessel, cells were seeded under rotary cell culture to obtain a homogeneous cell seeding in the inner wall of the devices. This is a simple and reproducible method that allows the generation of blood vessel models in vitro.

Survivin inhibition with YM155 ameliorates experimental pulmonary arterial hypertension.

Background: Imbalance between cell proliferation and apoptosis underlies the development of pulmonary arterial hypertension (PAH). Current vasodilator treatment of PAH does not target the uncontrolled proliferative process in pulmonary arteries. Proteins involved in the apoptosis pathway may play a role in PAH and their inhibition might represent a potential therapeutic target. Survivin is a member of the apoptosis inhibitor protein family involved in cell proliferation. Objectives: This study aimed to explore the potential role of survivin in the pathogenesis of PAH and the effects of its inhibition. Methods: In SU5416/hypoxia-induced PAH mice we assessed the expression of survivin by immunohistochemistry, western-blot analysis, and RT-PCR; the expression of proliferation-related genes (Bcl2 and Mki67); and the effects of the survivin inhibitor YM155. In explanted lungs from patients with PAH we assessed the expression of survivin, BCL2 and MKI67. Results: SU5416/hypoxia mice showed increased expression of survivin in pulmonary arteries and lung tissue extract, and upregulation of survivin, Bcl2 and Mki67 genes. Treatment with YM155 reduced right ventricle (RV) systolic pressure, RV thickness, pulmonary vascular remodeling, and the expression of survivin, Bcl2, and Mki67 to values similar to those in control animals. Lungs of patients with PAH also showed increased expression of survivin in pulmonary arteries and lung extract, and also that of BCL2 and MKI67 genes, compared with control lungs. Conclusion: We conclude that survivin might be involved in the pathogenesis of PAH and that its inhibition with YM155 might represent a novel therapeutic approach that warrants further evaluation.

Refined risk stratification, current treatment, and new therapeutic approaches in pulmonary arterial hypertension.

The 2022 European Society of Cardiology/European Respiratory Society (ESC/ERS) guidelines for pulmonary hypertension have introduced arefined risk stratification to guide both initial and subsequent treatment of pulmonary arterial hypertension (PAH). The risk stratification at PAH diagnosis still comprises three risk categories (low, intermediate, high) and lists some new parameters. As the estimated 1‑year mortality is more than 20% in high-risk patients after diagnosis, an initial triple-combination therapy including parenteral prostacyclin analogues is recommended for this group. All other patients should receive adual-combination therapy with an endothelin receptor antagonist and aphosphodiesterase‑5 inhibitor. However, this approach of initial combination therapy is only recommended for classic PAH, while monotherapy followed by regular follow-up and individualized therapy should be used for patients with cardiopulmonary comorbidities. For PAH patients without cardiopulmonary comorbidities, it is recommended to assess their risk at follow-up with anew 4‑strata classification, where the intermediate-risk group is split on the basis of three noninvasive parameters. Importantly, changes from intermediate-high to intermediate-low risk have been shown to be associated with abetter prognosis. In addition, the recommendations on treatment escalation became more precise with the addition of aprostacyclin receptor agonist or switching aphosphodiesterase‑5 inhibitor to asoluble guanylate cyclase stimulator for intermediate-low risk and proceeding to triple-combination therapy with parenteral prostacyclin analogues already for intermediate-high risk. With sotatercept, the first non-vasodilator PAH treatment will become available in the near future to further enrich our treatment options for this chronic and still severe disease.

Endothelial progenitor cell-derived exosomes inhibit pulmonary artery smooth muscle cell in vitro proliferation and resistance to apoptosis by modulating the Mitofusin-2 and Ras-Raf-ERK1/2 signaling pathway

Pulmonary arterial hypertension (PAH) mainly occurs as a result of abnormal proliferation and apoptosis resistance of pulmonary artery smooth muscle cells (PASMCs). Endothelial progenitor cell (EPC)-derived exosomes (Exos) (EPC-Exos) relieve PAH. However, there is still insufficient knowledge of whether EPC-Exos contribute to the pathological process of PAH, especially for PASMC repair. This study aimed to determine the effects of EPC-Exos on the proliferation, migration, and apoptosis of PASMCs and explore the possible underlying molecular mechanisms through bioinformatics analysis and in vitro testing. Bioinformatics analysis showed that the Ras signaling pathway and Exos were crucial in PAH. The PAH differential microRNAs (miRNAs) and miRNAs identified in EPC-Exos were intersected to obtain miR-21-5p. A target gene prediction program predicted mitofusin-2 (Mfn2) as a potential target of miR-21-5p. Cellular experiments demonstrated that EPC-Exos attenuated the viability, proliferation, migration, and apoptosis resistance of PASMCs under hypoxia. Mechanistically, EPC-Exos significantly upregulated Mfn2 expression and attenuated Ras-Raf-ERK1/2 signaling pathway activity. In conclusion, EPC-Exos suppress cell viability, proliferation, and migration and promote apoptosis in PASMCs under hypoxic conditions. It is possible to transport miR-21-5p to improve the expression of Mfn2 and inhibit the Ras-Raf-ERK1/2 signaling pathway directly or by targeting the expression of Mfn2. EPC-Exos are a potential therapeutic candidate for the treatment of PAH.

The HIF-1α/miR-26a-5p/PFKFB3/ULK1/2 axis regulates vascular remodeling in hypoxia-induced pulmonary hypertension by modulation of autophagy.

Pulmonary arterial hypertension (PAH) is a progressive and life-threatening disease characterized by pulmonary vascular remodeling, which may cause right heart failure and even death. Accumulated evidence confirmed that microRNA-26 family play critical roles in cardiovascular disease; however, their function in PAH remains largely unknown. Here, we investigated the expression of miR-26 family in plasma from PAH patients using quantitative RT-PCR, and identified miR-26a-5p as the most downregulated member, which was also decreased in hypoxia-induced pulmonary arterial smooth muscle cell (PASMC) autophagy models and lung tissues of PAH patients. Furthermore, chromatin immunoprecipitation (ChIP) analysis and luciferase reporter assays revealed that hypoxia-inducible factor 1α (HIF-1α) specifically interacted with the promoter of miR-26a-5p and inhibited its expression in PASMCs. Tandem mRFP-GFP-LC3B fluorescence microscopy demonstrated that miR-26a-5p inhibited hypoxia-induced PAMSC autophagy, characterized by reduced formation of autophagosomes and autolysosomes. In addition, results showed that miR-26a-5p overexpression potently inhibited PASMC proliferation and migration, as determined by cell counting kit-8, EdU staining, wound-healing, and transwell assays. Mechanistically, PFKFB3, ULK1, and ULK2 were direct targets of miR-26a-5p, as determined by dual-luciferase reporter gene assays and western blots. Meanwhile, PFKFB3 could further enhance the phosphorylation level of ULK1 and promote autophagy in PASMCs. Moreover, intratracheal administration of adeno-miR-26a-5p markedly alleviated right ventricular hypertrophy and pulmonary vascular remodeling in hypoxia-induced PAH rat models in vivo. Taken together, the HIF-1α/miR-26a-5p/PFKFB3/ULK1/2 axis plays critical roles in the regulation of hypoxia-induced PASMC autophagy and proliferation. MiR-26a-5p may represent as an attractive biomarker for the diagnosis and treatment of PAH.