Pulmonary hypertension: diagnostic approach and optimal management

Unraveling the genetic landscape of pulmonary arterial hypertension in Indian patients: A transcriptome study

BACKGROUND

Pulmonary hypertension (PH) is the abnormal elevation of pressure in the pulmonary vascular system, with various underlying causes. A specific type of PH is pulmonary arterial hypertension (PAH), a severe condition characterized by high pulmonary arterial pressure resulting from structural changes in distal pulmonary vessels, altered arterial tone, and inflammation. This leads to right ventricular hypertrophy and heart failure. The molecular mechanisms behind PAH are not well understood. This manuscript aims to elucidate these mechanisms using the genetic tool, aiding in diagnosis and treatment selection.

METHOD

In our present study, we have obtained blood samples from both patients with pulmonary arterial hypertension (PAH) and healthy individuals. We conducted a comparative transcriptome analysis to identify genes that are either upregulated or downregulated in PAH patients when compared to the control group. Subsequently, we carried out a validation study focusing on the log2-fold downregulated genes in PAH, employing Quantitative Real-Time PCR for confirmation. Additionally, we quantified the proteins encoded by the validated genes using the ELISA technique.

RESULTS

The results of the transcriptome analysis revealed that 97 genes were significantly upregulated, and 6 genes were significantly downregulated. Among these, we chose to focus on and validate only four of the downregulated genes, as they were directly or indirectly associated with the hypertension pathway. We also conducted validation studies for the proteins encoded by these genes, and the results were consistent with those obtained in the transcriptome analysis.

CONCLUSION

In conclusion, the findings of this study indicate that the four validated genes identified in the context of PAH can be further explored as potential targets for both diagnostic and therapeutic applications.

Evaluation of maternal-fetal outcomes in pregnancy complicated with severe pulmonary hypertension and its influencing factors: a single-center retrospective study in China

OBJECTIVE

Pregnancy is not recommended for patients with severe pulmonary hypertension (PH) due to the significant risks it poses to both the mother and fetus. The objective of this study is to describe the maternal-fetal outcomes in pregnant women with PH and identify the factors that influence these outcomes.

METHOD

This retrospective study analyzed clinical data from 25 patients with severe PH who were admitted to our hospital between January 2018 and December 2022. The data we used came from a public general hospital in Fujian Province.

RESULTS

The mean systolic pulmonary artery pressure (sPAP) of 25 patients was 105.12 ± 22.70 mmHg. All patients had received one or more multidisciplinary team (MDT) treatments before terminating their pregnancies. Among the pregnant women, four experienced a pulmonary hypertensive crisis (PHC), seven had heart failure, and one had postpartum hemorrhage (PPH). Among them, seven (28%) pregnant women died primarily due to heart failure and PHC. Among the fetal outcomes, twelve resulted in therapeutic abortion, and eleven resulted in preterm birth. Among the perinatal complications, eleven infants (84.6%) were born prematurely, six infants (46.2%) experienced neonatal asphyxia, eight infants (61.5%) had low birth weight, and two infants (15.4%) died during the perinatal period. According to the etiology, seven individuals had idiopathic pulmonary arterial hypertension (iPAH), ten had pulmonary arterial hypertension associated with congenital heart disease (CHD-PAH), six had pulmonary hypertension associated with left heart disease (LDH-PH), and two had pulmonary arterial hypertension caused by other diseases (oPAH). The sPAP levels of iPAH and CHD-PAH were significantly higher than those of LDH-PH and oPAH (p < 0.05). Additionally, the gestational weeks of LDH-PH were higher than those of iPAH (p < 0.05). The number of patients with New York Heart Association (NYHA) heart function grade III-V was higher in the death group compared to the non-death group (p < 0.05).

CONCLUSION

Pregnancy in women with severe PH carries a high risk of mortality. Therefore, contraception is strongly recommended for these women. NYHA cardiac function grade III-IV was useful in predicting the risk of mortality.

High-Altitude Andean H194R HIF2A Allele Is a Hypomorphic Allele

For over 10,000 years, Andeans have resided at high altitude where the partial pressure of oxygen challenges human survival. Recent studies have provided evidence for positive selection acting in Andeans on the HIF2A (also known as EPAS1) locus, which encodes for a central transcription factor of the hypoxia-inducible factor pathway. However, the precise mechanism by which this allele might lead to altitude-adaptive phenotypes, if any, is unknown. By analyzing whole genome sequencing data from 46 high-coverage Peruvian Andean genomes, we confirm evidence for positive selection acting on HIF2A and a unique pattern of variation surrounding the Andean-specific single nucleotide variant (SNV), rs570553380, which encodes for an H194R amino acid substitution in HIF-2α. Genotyping the Andean-associated SNV rs570553380 in a group of 299 Peruvian Andeans from Cerro de Pasco, Peru (4,338 m), reveals a positive association with increased fraction of exhaled nitric oxide, a marker of nitric oxide biosynthesis. In vitro assays show that the H194R mutation impairs binding of HIF-2α to its heterodimeric partner, aryl hydrocarbon receptor nuclear translocator. A knockin mouse model bearing the H194R mutation in the Hif2a gene displays decreased levels of hypoxia-induced pulmonary Endothelin-1 transcripts and protection against hypoxia-induced pulmonary hypertension. We conclude the Andean H194R HIF2A allele is a hypomorphic (partial loss of function) allele.

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.

Predictors of Maternal Death Among Women With Pulmonary Hypertension in China From 2012 to 2020: A Retrospective Single-Center Study

Background

Previous studies have suggested that pregnant women with pulmonary hypertension (PH) have high maternal mortality. However, indexes or factors that can predict maternal death are lacking.

Methods

We retrospectively reviewed pregnant women with PH admitted for delivery from 2012 to 2020 and followed them for over 6 months. The patients were divided into two groups according to 10-day survival status after delivery. Predictive models and predictors for maternal death were identified using four machine learning algorithms: naïve Bayes, random forest, gradient boosting decision tree (GBDT), and support vector machine.

Results

A total of 299 patients were included. The most frequent PH classifications were Group 1 PH (73.9%) and Group 2 PH (23.7%). The mortality within 10 days after delivery was 9.4% and higher in Group 1 PH than in the other PH groups (11.7 vs. 2.6%, P = 0.016). We identified 17 predictors, each with a P-value < 0.05 by univariable analysis, that were associated with an increased risk of death, and the most notable were pulmonary artery systolic pressure (PASP), platelet count, red cell distribution width, N-terminal brain natriuretic peptide (NT-proBNP), and albumin (all P < 0.01). Four prediction models were established using the candidate variables, and the GBDT model showed the best performance (F1-score = 66.7%, area under the curve = 0.93). Feature importance showed that the three most important predictors were NT-proBNP, PASP, and albumin.

Conclusion

Mortality remained high, particularly in Group 1 PH. Our study shows that NT-proBNP, PASP, and albumin are the most important predictors of maternal death in the GBDT model. These findings may help clinicians provide better advice regarding fertility for women with PH.

REDD1 gene knockout alleviates vascular smooth muscle cell remodeling in pulmonary hypertension

OBJECTIVES

Regulated in development and DNA damage responses 1 (REDD1) is an important transcription factor regulating mitochondria homeostasis, which is the important pathological alteration of pulmonary hypertension (PH). However, it is unclear whether REDD1 regulates the PASMCs mitochondria homeostasis by the similar mechanism in pulmonary arterial remodeling induced by hypoxia.

METHODS

The global REDD1-knockout rats (REDD1-KO) on Sprague-Dawley background were used to generate a chronic hypoxia model of PH. Right ventricular hypertrophy and vascular remodeling were detected after exposure to hypoxia. Additionally, proliferation, apoptosis, migration, mitochondria homeostasis, and autophagy were performed in vivo and in vitro.

RESULTS

The current research found that in human and experimental rats of PH, REDD1 expression is upregulated in the PASMCs. REDD1 gene knockout alleviated hypoxia PH and hemodynamic changes effectively and reversed hypoxic pulmonary vascular remodeling. In addition, REDD1 knockdown reduces the impairment of mitochondrial function caused by hypoxia in HPASMCs via autophagy inhibition, and this process may be regulated through the Parkin gene. Moreover, REDD1 knockdown can effectively inhibit the proliferation and migration of hypoxic PASMCs, and induce their apoptosis in vivo and in vitro.

CONCLUSIONS

Our results suggested that REDD1 might be a potential target for improved pulmonary vascular remodeling in PH.

WITHDRAWN: Anti-inflammatory role and mechanism of microRNA-92b-3p in the progression of hypoxic pulmonary hypertension

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Pulmonary hypertension: Spectrum of disease, clinical presentation and treatment outcomes at the main respiratory pulmonary hypertension clinic in KwaZulu-Natal Province, South Africa

BACKGROUND

There are many causes of pulmonary hypertension (PH). However, the aetiology, management and treatment outcomes in South Africa (SA), which has a high burden of HIV, are lacking in the literature.

OBJECTIVES

To characterise patient demographics, aetiology, clinical presentation and management of patients presenting to the only government-funded PH clinic in Durban, SA.

METHODS

We retrospectively reviewed electronic charts of patients with confirmed PH who attended the respiratory PH clinic between 2011 and 2018. Demographic and clinical data, symptoms, pulmonary function testing, pulmonary artery pressure on echocardiography and treatment were analysed. Patients with group 2 PH were excluded from the present study as they were managed by cardiologists.

RESULTS

We identified 93 patients with confirmed PH and the majority were female (82.8%; n=77). The majority of the patients were between the ages of 30 and 39 years at the time of diagnosis. Most patients were black African (64.5%; n=60), followed by Indians (26.9%; n=25) and whites (8.6%; n=8). The most common cause of PH was group 1 (75%; n=70), followed by group 4 (13%; n=12) and then group 3 (12%; n=11). HIV-associated PH accounted for 27% of all patients and was the main cause of PH in those classified in group 1 (38%; n=29). Two-thirds (66%) of patients were treated with sildenafil, the only treatment that was available. Patients on treatment showed significant improvement indicated by the World Health Organization functional class, mean 6-minute walk test and reduction in mean pulmonary artery pressure on echocardiography.

CONCLUSION

HIV-associated PH is the most common cause of PH in SA. Sildenafil, the only drug available in our setting, is beneficial to most patients with PH.

Exercise Training for Pulmonary Hypertension: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Pulmonary hypertension (PH) is a chronic disease with a notable health burden; regular exercise may improve specific health outcome measures.

OBJECTIVE

The objective of this meta-analysis was to estimate the effectiveness of exercise training for PH patients.

DATA SOURCES

PubMed, CINAHL, SportDiscuss and Google Scholar databases and reference lists of included studies were searched.

STUDY SELECTION

The selection criteria were randomized controlled trials (RCTs) employing an exercise training intervention. Data were extracted from the entered studies for analysis. The primary outcomes were peak oxygen uptake (VO_2peak), anaerobic threshold (AT), 6-minute walk distance (6-MWD), and quality of life (QoL) measures (physical component score and mental component score). The analysis included 9 articles with a total of 302 participants: intervention (n = 154), and control (n = 148).

RESULTS

In the pooled analysis, improvements were seen in: VO_2peak, mean difference (MD) 2.79 ml/kg/min (95% CI 2.00 to 3.59, p < 0.00001); AT, MD 107.83 ml/min (95% CI 39.64 to 176.00, p = 0.002); and 6-MWD, MD 46.67 meters (95% CI 32.39 to 60.96, p < 0.00001). Differences were found in the SF-36 physical component score MD 3.57 (95% CI 2.04 to 5.10, p < 0.00001) and the SF-36 mental component score MD 3.92 (95% CI 1.92 to 5.91, p = 0.001).

CONCLUSION

This meta-analysis demonstrates exercise training has a beneficial effect on fitness, walking performance, and self-reported QoL in PH patients.

Efficacy of the thromboxane receptor antagonist NTP42 alone, or in combination with sildenafil, in the sugen/hypoxia-induced model of pulmonary arterial hypertension

NTP42 is a novel antagonist of the thromboxane A₂ receptor (TP) in development for the treatment of pulmonary arterial hypertension (PAH). Recent studies demonstrated that NTP42 and TP antagonism have a role in alleviating PAH pathophysiology. However, the efficacy of NTP42 when used in combination with existing PAH therapies has not yet been investigated. Herein, the Sugen 5416/hypoxia (SuHx)-induced PAH model was employed to evaluate the efficacy of NTP42 when used alone or in dual-therapy with Sildenafil, a PAH standard-of-care. PAH was induced in rats by injection of Sugen 5416 and exposure to hypoxia for 21 days. Thereafter, animals were treated orally twice-daily for 28 days with either vehicle, NTP42 (0.05 mg/kg), Sildenafil (50 mg/kg), or NTP42+Sildenafil (0.05 mg/kg + 50 mg/kg, respectively). While Sildenafil or NTP42 mono-therapy led to non-significant reductions in the SuHx-induced rises in mean pulmonary arterial pressure (mPAP) or right ventricular systolic pressure (RSVP), combined use of NTP42+Sildenafil significantly reduced these increases in mPAP and RVSP. Detailed histologic analyses of pulmonary vessel remodelling, right ventricular hypertrophy and fibrosis demonstrated that while NTP42 and Sildenafil in mono-therapy resulted in significant benefits, NTP42+Sildenafil in dual-therapy showed an even greater benefit over either drug used alone. In summary, combined use of NTP42+Sildenafil in dual-therapy confers an even greater benefit in treating or offsetting key aetiologies underlying PAH. These findings corroborate earlier preclinical findings suggesting that, through antagonism of TP signalling, NTP42 attenuates PAH pathophysiology, positioning it as a novel therapeutic for use alone or in combination therapy regimens.

NTP42, a novel antagonist of the thromboxane receptor, attenuates experimentally induced pulmonary arterial hypertension

BACKGROUND

NTP42 is a novel antagonist of the thromboxane prostanoid receptor (TP), currently in development for the treatment of pulmonary arterial hypertension (PAH). PAH is a devastating disease with multiple pathophysiological hallmarks including excessive pulmonary vasoconstriction, vascular remodelling, inflammation, fibrosis, in situ thrombosis and right ventricular hypertrophy. Signalling through the TP, thromboxane (TX) A₂ is a potent vasoconstrictor and mediator of platelet aggregation. It is also a pro-mitogenic, pro-inflammatory and pro-fibrotic agent. Moreover, the TP also mediates the adverse actions of the isoprostane 8-iso-prostaglandin F_2α, a free-radical-derived product of arachidonic acid produced in abundance during oxidative injury. Mechanistically, TP antagonists should treat most of the hallmarks of PAH, including inhibiting the excessive vasoconstriction and pulmonary artery remodelling, in situ thrombosis, inflammation and fibrosis. This study aimed to investigate the efficacy of NTP42 in the monocrotaline (MCT)-induced PAH rat model, alongside current standard-of-care drugs.

METHODS

PAH was induced by subcutaneous injection of 60 mg/kg MCT in male Wistar-Kyoto rats. Animals were assigned into groups: 1. 'No MCT'; 2. 'MCT Only'; 3. MCT + NTP42 (0.25 mg/kg BID); 4. MCT + Sildenafil (50 mg/kg BID), and 5. MCT + Selexipag (1 mg/kg BID), where 28-day drug treatment was initiated within 24 h post-MCT.

RESULTS

From haemodynamic assessments, NTP42 reduced the MCT-induced PAH, including mean pulmonary arterial pressure (mPAP) and right systolic ventricular pressure (RSVP), being at least comparable to the standard-of-care drugs Sildenafil or Selexipag in bringing about these effects. Moreover, NTP42 was superior to Sildenafil and Selexipag in significantly reducing pulmonary vascular remodelling, inflammatory mast cell infiltration and fibrosis in MCT-treated animals.

CONCLUSIONS

These findings suggest that NTP42 and antagonism of the TP signalling pathway have a relevant role in alleviating the pathophysiology of PAH, representing a novel therapeutic target with marked benefits over existing standard-of-care therapies.

Isoliquiritigenin Attenuates Monocrotaline-Induced Pulmonary Hypertension via Inhibition of the Inflammatory Response and PASMCs Proliferation

Pulmonary hypertension (PH) is a progressive and serious disease, where exacerbated inflammatory response plays a critical role. Isoliquiritigenin (ISL), an important flavonoid isolated from Glycyrrhizae radix, exhibits a wide range of pharmacological actions including anti-inflammation. Previously we found ISL alleviated hypoxia-induced PH; in the present study, to extend this, we evaluated the effects of ISL on monocrotaline (MCT)-induced PH and the relevant mechanisms. Rats received a single intraperitoneal injection of MCT, followed by intragastric treatments with ISL (10 mg/kg/d or 30 mg/kg/d) once a day for 28 days. The MCT administration increased the right ventricular systolic pressure (RVSP) (p < 0.001), the median width of pulmonary arteries (p < 0.01), and the weight ratio of the right ventricular wall/left ventricular wall plus septum (Fulton index) (p < 0.01) in rats; however, these changes were inhibited by both doses of ISL (p < 0.05). In addition, treatment with ISL suppressed the upregulated production of serum interleukin-6 (p < 0.01) and tumor necrosis factor-α (p < 0.05) by MCT and reversed the increases in the numbers of proliferating cell nuclear antigen (PCNA)-positive cells (p < 0.01) in the medial wall of pulmonary arteries. In in vitro experiments, ISL (10 μM, 30 μM, and 100 μM) inhibited excessive proliferation of cultured primary pulmonary artery smooth muscle cells (PASMCs) (p < 0.05, p < 0.01, and p < 0.001) in a dose-dependent manner and prevented an increase in the expressions of PCNA (p < 0.01) and phospho-Akt (p < 0.05) in PASMCs induced by hypoxia. These results suggest that ISL can attenuate MCT-induced PH via its anti-inflammatory and antiproliferative actions.