Idiopathic Pulmonary Arterial Hypertension Research Articles

Rhythm Disorders in Pulmonary Arterial Hypertension (PAH) - What Therapeutic Options are Available?

Rhythm disorders in PAH are rare. In practice, they pose a therapeutic management challenge. Right ventricular dysfunction associated with hypoxia influences the prescription of antiarrhythmics; some of them are even contraindicated. We report three cases of idiopathic PAH complicated by atrial flutter (2 cases) and atrial fibrillation (1 case). The patients experienced right heart failure after a stabilization phase with specific vasodilators (bosentan, sildenafil, iloprost). They were treated with oral amiodarone, alongside treatment for right heart failure. Potassium levels were normal. Beta-blockers were not prescribed due to severe right ventricular dysfunction with arterial hypotension. Unfortunately, two patients developed hyperthyroidism secondary to amiodarone. Through these observations, we will discuss the different therapeutic options in these situations, referencing the literature.

Association of non-insulin-based insulin resistance indices with disease severity and adverse outcome in idiopathic pulmonary arterial hypertension: a multi-center cohort study

BackgroundInsulin resistance (IR) plays an important role in the pathophysiology of cardiovascular disease. Recent studies have shown that diabetes mellitus and impaired lipid metabolism are associated with the severity and prognosis of idiopathic pulmonary arterial hypertension (IPAH). However, the relationship between IR and pulmonary hypertension is poorly understood. This study explored the association between four IR indices and IPAH using data from a multicenter cohort.MethodsA total of 602 consecutive participants with IPAH were included in this study between January 2015 and December 2022. The metabolic score for IR (METS-IR), triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio, triglyceride and glucose (TyG) index, and triglyceride-glucose-body mass index (TyG-BMI) were used to quantify IR levels in patients with IPAH. The correlation between non-insulin-based IR indices and long-term adverse outcomes was determined using multivariate Cox regression models and restricted cubic splines.ResultsDuring a mean of 3.6 years’ follow-up, 214 participants experienced all-cause death or worsening condition. Compared with in low to intermediate-low risk patients, the TG/HDL-C ratio (2.9 ± 1.7 vs. 3.3 ± 2.1, P = 0.003) and METS-IR (34.5 ± 6.7 vs. 36.4 ± 7.5, P < 0.001) were significantly increased in high to intermediate-high risk patients. IR indices correlated with well-validated variables that reflected the severity of IPAH, such as the cardiac index and stroke volume index. Multivariate Cox regression analyses indicated that the TyG-BMI index (hazard ratio [HR] 1.179, 95% confidence interval [CI] 1.020, 1.363 per 1.0-standard deviation [SD] increment, P = 0.026) and METS-IR (HR 1.169, 95% CI 1.016, 1.345 per 1.0-SD increment, P = 0.030) independently predicted adverse outcomes. Addition of the TG/HDL-C ratio and METS-IR significantly improved the reclassification and discrimination ability beyond the European Society of Cardiology (ESC) risk score.ConclusionsIR is associated with the severity and long-term prognosis of IPAH. TyG-BMI and METS-IR can independently predict clinical worsening events, while METS-IR also provide incremental predictive performance beyond the ESC risk stratification.

Lung Transplantation in Patients With Systemic Scleroderma—Description of the First Consecutive Cases in Poland: Case Series Report and a Short Literature Review

Pulmonary complications of systemic scleroderma (SSc), such as interstitial lung disease and pulmonary hypertension (PH), are responsible for up to 60% of deaths among patients. For many years, most centers considered SSc a contraindication to lung transplantation (LTx); however, recent publications show that appropriately selected SSc candidates for LTx give results comparable to patients with idiopathic PH or idiopathic pulmonary fibrosis. This paper presents the cases of a 60-year-old male patient (patient 1) and a 42-year-old female patient (patient 2) diagnosed with SSc in 2019 and 2013, respectively. In both patients, interstitial-fibrotic changes in the lungs leading to respiratory failure were confirmed by high-resolution computed tomography as well as pulmonary hypertension (WHO group 3), which was also diagnosed during right heart catheterization. In both cases, despite pharmacotherapy, pulmonary fibrosis progressed, leading to severe respiratory failure. The patients were referred for LTx qualification. LTx was possible to consider in patients due to the lack of significant changes in other internal organs. Double LTx was successfully performed in both patients (patient 1-July 19, 2022; patient 2-September 14, 2022). They were discharged from the hospital in good condition on the 22nd and 20th postoperative day, respectively. LTx is a last-chance therapy that saves lives among patients with extreme respiratory failure in the course of SSc. It prolongs and improves the quality of life. The selection of appropriate patients is key to the success of the procedure.

Fractional exhaled nitric oxide in idiopathic pulmonary arterial hypertension and mixed connective tissue disease complicating pulmonary hypertension

BackgroundFractional exhaled nitric oxide (FeNO) has been extensively studied in various causes of pulmonary hypertension (PH), but its utility as a noninvasive marker remains highly debated. The objective of our study was to assess FeNO levels in patients with idiopathic pulmonary arterial hypertension (IPAH) and mixed connective tissue disease complicating pulmonary hypertension (MCTD-PH), and to correlate them with respiratory functional data, disease severity, and cardiopulmonary function.MethodsWe collected data from 54 patients diagnosed with IPAH and 78 patients diagnosed with MCTD-PH at the Shanghai Pulmonary Hospital Affiliated to Tongji University. Our data collection included measurements of brain natriuretic peptide (pro-BNP), cardiopulmonary exercise test (CPET), pulmonary function test (PFT), impulse oscillometry (IOS), and FeNO levels. Additionally, we assessed World Health Organization functional class (WHO-FC) of each patient.Results(1) The fractional exhaled concentration of nitric oxide was notably higher in patients with IPAH compared to those with MCTD-PH. Furthermore, within the IPAH group, FeNO levels were found to be lower in cases of severe IPAH compared to mild IPAH (P = 0.024); (2) In severe pulmonary hypertension as per the WHO-FC classification, FeNO levels in IPAH exhibited negative correlations with FEV1/FVC (Forced Expiratory Velocity at one second /Forced Vital Capacity), MEF50% (Maximum Expiratory Flow at 50%), MEF25%, and MMEF75/25% (Maximum Mid-expiratory Flow between 75% and 25%), while in severe MCTD-PH, FeNO levels were negatively correlated with R20% (Resistance at 20 Hz); (3) ROC (Receiving operator characteristic curve) analysis indicated that the optimal cutoff value of FeNO for diagnosing severe IPAH was 23ppb; (4) While FeNO levels tend to be negatively correlated with peakPETO2(peak end-tidal partial pressure for oxygen) in severe IPAH, in mild IPAH they had a positive correlation to peakO2/Heart rate (HR). An interesting find was observed in cases of severe MCTD-PH, where FeNO levels were negatively correlated with HR and respiratory exchange ratio (RER), while positively correlated with O2/HR throughout the cardiopulmonary exercise test.ConclusionFeNO levels serve as a non-invasive measure of IPAH severity. Although FeNO levels may not assess the severity of MCTD-PH, their significant makes them a valuable tool when assessing severe MCTD-PH.

Blood urea nitrogen to serum albumin ratio as a new indicator of disease severity and prognosis in idiopathic pulmonary artery hypertension

BackgroundEmerging evidence has shown that the blood urea nitrogen to serum albumin ratio (BAR) is associated with the severity and prognosis of heart failure. However, its role in idiopathic pulmonary arterial hypertension (IPAH) remains unclear. This study investigated the associations between BAR and functional status, echocardiographic findings, hemodynamics, and long-term outcomes among patients with IPAH. MethodsThis study included consecutive patients who underwent right heart catheterization (RHC) and were diagnosed with IPAH between January 2013 and January 2018 at Fuwai Hospital. The primary outcome was the worsening of clinical symptoms. Spearman correlation coefficients were used to evaluate the association between the BAR and established markers of IPAH severity. Receiver operating characteristic (ROC) curve analysis was used to determine BAR's optimal cut-off and predictive performance. Kaplan–Meier analysis and Cox proportional hazard models assessed the relationship between BAR and clinical worsening. ResultsA total of 340 patients with IPAH were included in this study. BAR correlated with well-validated variables that reflected the severity of IPAH, such as World Health Organization functional class, 6-min walk distance, N-terminal pro-brain natriuretic peptide (NT-proBNP) level, mixed venous oxygen saturation, and cardiac index. Kaplan–Meier curves indicated that patients with BAR＞3.80 had a significantly higher clinical worsening rate (log-rank test, P < 0.001) than those with BAR≤3.80. Multivariate Cox analysis showed that BAR could independently predict clinical worsening [hazard ratio(HR):2.642, 95 % confidence interval (CI):1.659–4.208, P < 0.001]. In addition, BAR provided additional predictive value for the European Society of Cardiology (ESC)/European Respiratory Society (ERS) risk assessment score. ConclusionsBAR reflects disease severity and is independently associated with the prognosis of patients with IPAH.

Endothelial HIFα-PDGF-B to smooth muscle Beclin1 signaling sustains pathological muscularization in pulmonary hypertension.

Mechanisms underlying maintenance of pathological vascular hypermuscularization are poorly delineated. Herein, we investigated retention of smooth muscle cells (SMCs) coating normally unmuscularized distal pulmonary arterioles in pulmonary hypertension (PH) mediated by chronic hypoxia ± Sugen 5416, and reversal of this pathology. With hypoxia in mice or culture, lung endothelial cells (ECs) upregulated hypoxia-inducible factor (Hif)-1a and 2a which induce platelet-derived growth factor-B (PDGF-B), and these factors reduced to normoxic levels with re-normoxia. Re-normoxia reversed hypoxia-induced pulmonary vascular remodeling, but with EC HIFα over-expression during re-normoxia, pathological changes persisted. Conversely, after establishment of distal muscularization and PH, EC-specific deletion of Hif1a, Hif2a, or Pdgfb induced reversal. In human idiopathic pulmonary artery hypertension, HIF1A, HIF2A, PDGFB and autophagy-mediating gene products, including Beclin1, were upregulated in pulmonary artery SMCs and/or lung lysates. Furthermore, in mice, hypoxia-induced EC-derived PDGF-B upregulated Beclin1 in distal arteriole SMCs, and after distal muscularization was established, re-normoxia, EC Pdgfb deletion or treatment with STI571 (which inhibits PDGF receptors) downregulated SMC Beclin1 and other autophagy products. Finally, SMC-specific Becn1 deletion induced apoptosis, reversing distal muscularization and PH mediated by hypoxia ± Sugen 5416. Thus, chronic hypoxia induction of HIFα-to-PDGF-B axis in ECs is required for non-cell autonomous Beclin1-mediated survival of pathological distal arteriole SMCs.

Serum PM20D1 levels in patients with idiopathic pulmonary arterial hypertension and its clinical significance

ObjectiveThis study aimed to investigate the serum levels of Peptidase M20 domain containing 1 (PM20D1) in idiopathic pulmonary arterial hypertension (IPAH) patients and examine its association with lipid metabolism, echocardiography, and hemodynamic parameters.MethodsThis prospective observational research enrolled 103 IPAH patients from January 2018 to January 2022. Enzyme-linked immunosorbent assay (ELISA) was used to measure the serum PM20D1 levels in all patients before treatment within 24 h of admission. Demographic data, echocardiography, hemodynamic parameters and serum biomarkers were also collected.ResultsThe IPAH patients in the deceased group had significantly elevated age, right atrial (RA), mean pulmonary arterial pressure (mPAP), mean right atrial pressure (mRAP), pulmonary capillary wedge pressure (PCWP), pulmonary vascular resistance (PVR) and significantly decreased 6 min walking distance (6MWD) and tricuspid annulus peak systolic velocity (TASPV). IPAH patients showed significant decreases in serum PM20D1, low-density lipoprotein cholesterol (LDL-C), and albumin (ALB). Additionally, PM20D1 was negatively correlated with RA, NT-proBNP and positively correlated with PVR, ALB, 6MWD, and TAPSV. Moreover, PM20D1 has the potential as a biomarker for predicting IPAH patients’ prognosis. Finally, logistic regression analysis indicated that PM20D1, ALB, NT-proBNP, PVR, TASPV, RA and 6MWD were identified as risk factors for mortality in IPAH patients.ConclusionOur findings indicated that the serum levels of PM20D1 were significantly decreased in IPAH patients with poor prognosis. Moreover, PM20D1 was identified as a risk factor associated with mortality in IPAH patients.

Positive Vasoreactivity Testing in Pulmonary Arterial Hypertension: Therapeutic Consequences, Treatment Patterns, and Outcomes in the Modern Management Era.

Among patients with pulmonary arterial hypertension (PAH), acute vasoreactivity testing during right heart catheterization may identify acute vasoresponders, for whom treatment with high-dose calcium channel blockers (CCBs) is recommended. However, long-term outcomes in the current era remain largely unknown. We sought to evaluate the implications of acute vasoreactivity response for long-term response to CCBs and other outcomes. Patients diagnosed with PAH between January 1999 and December 2018 at 15 pulmonary hypertension centers were included and analyzed retrospectively. In accordance with current guidelines, acute vasoreactivity response was defined by a decrease of mean pulmonary artery pressure by ≥10 mm Hg to reach <40 mm Hg, without a decrease in cardiac output. Long-term response to CCBs was defined as alive with unchanged initial CCB therapy with or without other initial PAH therapy and World Health Organization functional classification I/II or low European Society of Cardiology/European Respiratory Society risk status at 12 months after initiation of CCBs. Patients were followed for up to 5 years; clinical measures, outcome, and subsequent treatment patterns were captured. Of 3702 patients undergoing right heart catheterization for PAH diagnosis, 2051 had idiopathic, hereditary, or drug-induced PAH, of whom 1904 (92.8%) underwent acute vasoreactivity testing. A total of 162 patients fulfilled acute vasoreactivity response criteria and received an initial CCB alone (n=123) or in combination with another PAH therapy (n=39). The median follow-up time was 60.0 months (interquartile range, 30.8-60.0), during which overall survival was 86.7%. At 12 months, 53.2% remained on CCB monotherapy, 14.7% on initial CCB plus another initial PAH therapy, and the remaining patients had the CCB withdrawn or PAH therapy added. CCB long-term response was found in 54.3% of patients. Five-year survival was 98.5% in long-term responders versus 73.0% in nonresponders. In addition to established vasodilator responder criteria, pulmonary artery compliance at acute vasoreactivity testing, low risk status and NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels at early follow-up correlated with long-term response and predicted survival. Our data display heterogeneity within the group of vasoresponders, with a large subset failing to show a sustained satisfactory clinical response to CCBs. This highlights the necessity for comprehensive reassessment during early follow-up. The use of pulmonary artery compliance in addition to current measures may better identify those likely to have a good long-term response.

Calcium channel blockers in patients with pulmonary arterial hypertension receiving PAH-specific treatment

BackgroundCalcium channel blockers (CCB) are the first effective therapy for vasoreactive patients with idiopathic pulmonary arterial hypertension (IPAH). However, the advent of modern PAH-specific drugs may undermine the role of vasoreactivity tests and CCB treatment. We aimed to clarify the effect of acute vasoreactivity testing and CCB on patients with IPAH receiving PAH-specific treatment. MethodsWe retrospectively investigated consecutive patients with IPAH (n = 136) diagnosed between 2000 and 2020 and collected data from patients who underwent acute vasoreactivity testing using inhaled nitric oxide (NO). The effects of vasoreactivity testing and CCB therapy were reviewed. Long-term survival was analysed using the Kaplan–Meier method. ResultsAcute vasoreactivity testing was performed in 49% of patients with IPAH (n = 67), including 23 patients (34%) receiving PAH-specific therapy without vasoreactivity testing. Eight patients (12%), including three patients (4.4%) receiving PAH-specific therapy, presented acute responses at vasoreactivity testing. They received high-dose CCB therapy (CCB monotherapy for five patients [7.5%] and CCB therapy and PAH-specific therapy for three patients [4.4%]). They presented a significant improvement in clinical parameters and near-normalisation of haemodynamics (mean pulmonary arterial pressure decreased from 46 [interquartile range: 40–49] to 19.5 [interquartile range: 18–23] mmHg [P < .001] at 1-year follow-up). All eight vasoreactive responders receiving CCB therapy showed better long-term survival than non-responders treated with PAH-specific therapy (P < .001). ConclusionsCCB therapy benefited patients with IPAH who showed acute response to vasoreactivity testing using inhaled NO, even when receiving modern PAH-specific therapy. Acute vasoreactive responders may benefit more from CCB than from PAH-specific therapy.

Corosolic acid attenuates platelet-derived growth factor signaling in macrophages and smooth muscle cells of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive and life-threatening disease that is characterized by vascular remodeling of the pulmonary artery. Pulmonary vascular remodeling is primarily caused by the excessive proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs), which are facilitated by perivascular inflammatory cells including macrophages. Corosolic acid (CRA) is a natural pentacyclic triterpenoid that exerts anti-inflammatory effects. In the present study, the effects of CRA on the viability of macrophages were examined using monocrotaline (MCT)-induced PAH rats and human monocyte-derived macrophages. Although we previously reported that CRA inhibited signal transducer and activator of transcription 3 (STAT3) signaling and ameliorated pulmonary vascular remodeling in PAH, the inhibitory mechanism remains unclear. Therefore, the underlying mechanisms were investigated using PASMCs from idiopathic PAH (IPAH) patients. In MCT-PAH rats, CRA inhibited the accumulation of macrophages around remodeled pulmonary arteries. CRA reduced the viability of human monocyte-derived macrophages. In IPAH-PASMCs, CRA attenuated cell proliferation and migration facilitated by platelet-derived growth factor (PDGF)-BB released from macrophages and PASMCs. CRA also downregulated the expression of PDGF receptor β and its signaling pathways, STAT3 and nuclear factor-κB (NF-κB). In addition, CRA attenuated the phosphorylation of PDGF receptor β and STAT3 following the PDGF-BB simulation. The expression and phosphorylation levels of PDGF receptor β after the PDGF-BB stimulation were reduced by the small interfering RNA knockdown of NF-κB, but not STAT3, in IPAH-PASMCs. In conclusion, CRA attenuated the PDGF-PDGF receptor β-STAT3/NF-κB signaling axis in macrophages and PASMCs, and thus, ameliorated pulmonary vascular remodeling in PAH.

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

Idiopathic Pulmonary Arterial Hypertension (IPAH) is characterized by extensive pulmonary vascular remodeling due to plexiform and obliterative lesions, media hypertrophy, inflammatory cell infiltration, and alterations of the adventitia. Test the hypothesis that microscopic IPAH vascular lesions express unique molecular profiles, which collectively are different from control pulmonary arteries. We used digital spatial transcriptomics to profile the genome-wide differential transcriptomic signature of key pathological lesions (plexiform, obliterative, intima+media hypertrophy, and adventitia) in IPAH lungs (n= 11) and compared these data to the intima+media and adventitia of control pulmonary artery (n=5). We detected 8273 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 (i) genes associated with TGFβ-signaling and (ii) mutated genes affecting the extracellular matrix and endothelial-mesenchymal transformation. Plexiform lesions and IPAH adventitia showed upregulation of genes involved in immune and interferon 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. 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.

(18)F-fluorodeoxyglucose uptake by positron emission tomography in patients with IPAH and CTEPH.

Pulmonary arterial hypertension (PAH) is driven by pathologies associated with increased metabolism such as pulmonary revascularization, vasoconstriction and smooth muscle cell proliferation in pulmonary artery wall. 18-fluorodeoxyglucose positron emission tomography (18FDG-PET) is an imaging technique sensitive to glucose metabolism and might be considered as a non-invasive method for diagnosis due to significant role of inflammation in idiopathic pulmonary artery hypertension (IPAH) and chronic thromboembolic pulmonary hypertension (CTEPH). The present study aimed to investigate the role of PET/CT imaging of patients with IPAH and CTEPH as an alternative diagnosis method. Demographic characteristics, FDG uptake in lungs, pulmonary artery and right ventricle (RV) of 17 patients (10 IPAH, 7 CTEPH), and 30 controls were evaluated. PET scanning, 6-min walk test, pro-BNP level, right heart catheterization of patients were performed both at the onsert and after 6-month PAH specific treatment. IPAH and CTEPH patients had significantly higher left lung FDG (p = 0.006), right lung FDG (p = 0.004), right atrial (RA) FDG (p < 0.001) and RV FDG (p < 0.001) uptakes than controls. Positive correlation was detected between the RV FDG uptake and the mean pulmonary artery pressure (mPAP) (r = 0.7, p = 0.012) and between the RA FDG uptake and the right atrial pressure (RAP) (r = 0.5, p = 0.02). Increased RV FDG and RA FDG uptakes predicts the presence of pulmonary hypertension and correlates with mPAP and RAP, respectively, which are important indicators in the prognosis of PAH. Further studies are required whether FDG PET imaging can be used to diagnose or predict the prognosis of pulmonary hypertension.

Predictors of early mortality after lung transplantation for idiopathic pulmonary arterial hypertension.

Lung transplantation remains an important therapeutic option for idiopathic pulmonary arterial hypertension (IPAH),yet short-term survival is the poorest among the major diagnostic categories. We sought to develop a prediction model for 90-day mortality using the United Network for Organ Sharing database for adults with IPAH transplanted between 2005 and 2021. Variables with a pvalue ≤ 0.1 on univariate testing were included in multivariable analysis to derive the best subset model. The cohort comprised 693 subjects, of whom 71 died (10.2%) within 90 days of transplant. Significant independent predictors of early mortality were: extracorporeal circulatory support and/or mechanical ventilation at transplant (OR:3; CI: 1.4-5), pulmonary artery diastolic pressure (OR:1.3 per 10 mmHg; CI: 1.07-1.56), forced expiratory volume in the first second percent predicted (OR:0.8 per 10%; CI: 0.7-0.94), recipient total bilirubin >2 mg/dL (OR:3; CI: 1.4-7.2) and ischemic time >6 h (OR: 1.7, CI: 1.01-2.86). The predictive model was able to distinguish 25% of the cohort with a mortality of ≥20% from 49% with a mortality of ≤5%. We conclude that recipient variables associated with increasing severity of pulmonary vascular disease, including pretransplant advanced life support, and prolonged ischemic time are important risk factors for 90-day mortality after lung transplant for IPAH.

Pediatric Lung Transplantations: New Possibilities and Challenges in Treatment of Children With End-Stage Respiratory Failure

Lung transplantation (LTx) is the last treatment option for children with end-stage respiratory failure. According to the literature, cystic fibrosis remains the most common cause of pediatric LTx. The study aimed to assess the characteristics of pediatric LTx recipients as well as the outcomes of the transplantation. Our study is a single-center retrospective review of clinical data of all 11 patients who underwent a LTx before the age of 18 years between the years 2016 and 2020. Medical records were examined for patients' characteristics, general treatment, and complications. There were a total of 11 patients (8 males) with a median age 14.5 years (range: 11-17). The primary diseases that led to LTx were: cystic fibrosis in 8 patients (72.73%), hereditary hemorrhagic telangiectasia in 2 patients (18.18%), and idiopathic pulmonary arterial hypertension in 1 patient (9.09%). Median period from qualification to LTx was 235.55 days (range: 11-748). Two patients (18.18%) underwent lung retransplantation after 3 and 5 years. One patient passed away 10 months after surgery due to noncompliance. Pediatric lung transplantation is less common than lung transplantation in adults. It also differs in fields of donors accessibility, stronger immune system response and noncompliance that may lead to graft failure.

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

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 (R) 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. Bioinformatic analyses were used to explore the mechanism of 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. 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 (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. 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.

Coexistence of pulmonary arterial hypertension and straight back syndrome in a patient with a novel BMPR2 variant affecting cytoplasmic tail domain

BackgroundPathologic variants in the bone morphogenetic protein receptor-2 (BMPR2) gene cause a pulmonary arterial hypertension phenotype in an autosomal-dominant pattern with incomplete penetrance. Straight back syndrome is one of the causes of pseudo-heart diseases. To date, no cases of idiopathic or heritable pulmonary arterial hypertension with straight back syndrome have been reported.Case presentationA 30-year-old female was diagnosed with pulmonary arterial hypertension by right heart catheterization. Computed tomography revealed a decreased anteroposterior thoracic space with heart compression, indicating a straight back syndrome. Genetic analysis by whole exome sequencing identified a novel c.2423_2424delGT (p.G808Gfs*4) germline frameshift variant within BMPR2 affecting the cytoplasmic tail domain.ConclusionsThis is the first report of different straight back characteristics in heritable pulmonary arterial hypertension with a novel germline BMPR2 variant. This finding may provide a new perspective on the variable penetrance of the pulmonary arterial hypertension phenotype.

Systemic sclerosis-associated pulmonary arterial hypertension is characterized by a distinct peripheral T helper cell profile.

Systemic sclerosis (SSc) is characterized by multiple clinical manifestations. Vasculopathy is a main disease hallmark and ranges in severity from an exacerbated Raynaud phenomenon to pulmonary arterial hypertension (PAH). The potential involvement of immune system in SSc associated vascular abnormalities is not clear. Here, we set out to study SSc-related immune parameters and determine whether and which peripheral T cell subsets associate with vascular severity in SSc patients. Peripheral blood and clinical data were collected from 30 SSc patients, 5 patients with idiopathic pulmonary arterial hypertension (IPAH) and 15 age and sex-matched healthy donors (HD). In this cross-sectional cohort SSc patients with PAH (n = 15) were matched for their age, sex and medication with SSc patients with no signs of PAH (n = 15). Lymphocyte subsets were quantified by multi-colour flow cytometry. SSc patients exhibited elevated percentages of T peripheral helper cells (Tph), CD4+GZMB+ T cells and decreased levels of Th1 cells compared with HD. Increased presence of both CD4+ and CD8+ exhausted-like (CD28-) T cells, characterized by raised cytokine and cytotoxic signature, was also observed in SSc compared with HD blood. Furthermore, IL-4 expressing CD4+CD8+ T cells were significantly increased in SSc peripheral blood. Interestingly, the presence of PAH in SSc was accompanied by a distinct T helper profile, characterized by raised percentages of Th17 and Tph cells. SSc patients with severe vasculopathy (presence of PAH) exhibited a distinct T cell profile, suggesting for a potential role of auto-immune inflammation in SSc vascular complications.

Effect of epoprostenol-induced thrombocytopaenia on lung transplantation for pulmonary arterial hypertension.

Preoperative intravenous epoprostenol therapy can cause thrombocytopaenia, which may increase the risk of perioperative bleeding during lung transplantation. This study aimed to determine whether lung transplantation can be safely performed in patients with epoprostenol-induced thrombocytopaenia. From June 2008 to July 2022, we performed 37 lung transplants in patients with pulmonary arterial hypertension (PAH), including idiopathic PAH (n = 26), congenital heart disease-associated PAH (n = 7), pulmonary veno-occlusive disease (n = 3) and peripheral pulmonary artery stenosis (n = 1) at our institution. Of these, 26 patients received intravenous epoprostenol therapy (EPO group), whereas 11 patients were treated with no epoprostenol (no-EPO group). We retrospectively analysed the preoperative and postoperative platelet counts and post-transplant outcomes in each group. Preoperative platelet counts were relatively lower in the EPO group than in the no-EPO group (median EPO: 127000 vs no-EPO: 176000/μl). However, blood loss during surgery was similar between the 2 groups (EPO: 2473 ml vs no-EPO: 2615 ml). The platelet counts significantly increased over 1 month after surgery, and both groups showed similar platelet counts (EPO: 298000 vs no-EPO: 284000/μl). In-hospital mortality (EPO: 3.9% vs no-EPO: 18.2%) and the 3-year survival rate (EPO: 91.4% vs no-EPO: 80.8%) were similar between the 2 groups. Patients with PAH treated with intravenous epoprostenol showed relatively lower platelet counts, which improved after lung transplantation with good post-transplant outcomes.

Association of pulmonary hypertension with outcomes in patients with Systemic sclerosis and other connective tissue disorders: review and meta-analysis.

Pulmonary hypertension (PH) is a frequent complication of connective tissue disorders (CTDs), with a major impact on the prognosis of the disease. The aim of our study was to perform a systemic review and meta-analysis of published literature evaluating survival function in patients with systemic sclerosis (SSc) with and without PH and to compare survival function between patients with SSc, systemic lupus erythematosus (SLE), other CTDs, and conditions associated with PH. The established protocol of the Cochrane Collaboration Steps and meta-analysis of observational studies in epidemiology recommendations (MOOSE) were used. 7 studies, including 1470 SSc-PH patients and 1368 SSc patients without PH, and 4 studies, including 108 SLE-PH patients and 1288 SLE patients without PH, assessed survival function were selected. Six studies (including 777 SSc, 249 SLE, 90 idiopathic pulmonary arterial hypertension (IPAH) and 29 primary Sjogren's syndrome patients) comparing survival function in different subgroups of patients with confirmed PH were included. SSc patients with PH showed the worst survival as compared to SSc patients without PH [OR (95% CI) 3.70 (2.42-5.67); p<0.00001]. The same pattern was observed in patients with SLE. SSc patients with PH were characterized by lower survival function compared to other reasons for PH, including SLE [OR (95% CI) 2.76 (1.95-3.91); p<0.00001]. Patients with SSc-PH are characterized by significantly lower survival function as compared to SSc patients without PH. Among the different entities of PH, SSc shows the worst survival, underlining prognostic significance of detection and evaluation of PH according to the currently established approach.

Identification of potential biomarkers for idiopathic pulmonary arterial hypertension using single-cell and bulk RNA sequencing analysis.

Idiopathic pulmonary arterial hypertension (IPAH) is a rare and severe cardiopulmonary disease with a challenging prognosis, and its underlying pathogenesis remains elusive. A comprehensive understanding of IPAH is crucial to unveil potential diagnostic markers and therapeutic targets. In this study, we investigated cellular heterogeneity and molecular pathology in IPAH using single-cell RNA sequencing (scRNA-seq) analysis. Our scRNA-seq results revealed significant alterations in three crucial signaling pathways in IPAH: the hypoxia pathway, TGF β pathway, and ROS pathway, primarily attributed to changes in gene expression within arterial endothelial cells. Moreover, through bulk RNA sequencing analysis, we identified differentially expressed genes (DEGs) enriched in GO and KEGG pathways, implicated in regulating cell adhesion and oxidative phosphorylation in IPAH lungs. Similarly, DEGs-enriched pathways in IPAH arterial endothelial cells were also identified. By integrating DEGs from three IPAH datasets and applying protein-protein interaction (PPI) analysis, we identified 12 candidate biomarkers. Subsequent validation in two additional PAH datasets led us to highlight five potential biomarkers (CTNNB1, MAPK3, ITGB1, HSP90AA1, and DDX5) with promising diagnostic significance for IPAH. Furthermore, real-time quantitative polymerase chain reaction (RT-qPCR) confirmed significant differences in the expression of these five genes in pulmonary arterial endothelial cells from PAH mice. In conclusion, our findings shed light on the pivotal role of arterial endothelial cells in the development of IPAH. Furthermore, the integration of single-cell and bulk RNA sequencing datasets allowed us to pinpoint novel candidate biomarkers for the diagnosis of IPAH. This work opens up new avenues for research and potential therapeutic interventions in IPAH management.