Pulmonary arterial hypertension: New pathophysiological insights and emerging therapeutic targets

Methodological Quality of Pulmonary Arterial Hypertension Treatment Evidence-Based Guidelines: A Systematic Review Using the AGREE II and AGREE REX Tools

PURPOSE

Pulmonary arterial hypertension (PAH) is a progressive disease with a poor prognosis, and its management should be grounded in well-developed clinical practice guidelines (CPG). Thus, we critically assess the methodological quality of the available CPG for pharmacological treatments for PAH.

METHODS

A systematic review (CRD42023387168) was performed in PubMed, Cochrane, Embase, and Tripdatabase (Jan-2023). Eligible records were appraised by four reviewers using the Appraisal of Guidelines, Research, and Evaluation Collaboration tool (AGREE II) and the complementary tool for assessing recommendations' quality and certainty, AGREE REX. Descriptive statistics were used to summarize the data.

RESULTS

Overall, 31 guidelines, mainly authored by professional societies (90%), targeting only physicians as primary users (84%), were identified. Guidelines presented a moderate overall quality (scores of 63% and 51% in AGREE II and AGREE REX, respectively), with a few domains showing slight improvements over the years. AGREE II "Scope and Purpose" (94%) and "Presentation Clarity" (99%) domains obtained the highest scores. The items related to "Stakeholder involvement," "Editorial independence," and "Clinical applicability" (AGREE REX) were fairly reported. Conversely, CPG lacks rigor in development (32% score, AGREE II), scarcely discusses the role of stakeholders, and provides deficient data on the implementation of recommendations (scores of 35% and 46% in AGREE II and AGREE REX, respectively). No differences in the quality of guidelines published by different developers or countries were observed (p > 0.05).

CONCLUSION

Methodological weaknesses are common among guidelines addressing PAH treatment, especially regarding scientific rigor, stakeholders' values and preferences, and facilitators and barriers to implementability. Particular attention should be given to developing future guidelines.

Effects of combined aerobic, resistance and inspiratory training in patients with pulmonary hypertension: A systematic review

BACKGROUND

Pulmonary hypertension (PH) is a serious progressive disorder of the modern world, characterized by endothelial dysfunction and impaired vasoreactivity. Patients with PH usually present exercise intolerance from the very early stages and reduced exercise capacity. Exercise training has been shown to have beneficial effects in patients with cardiovascular comorbidities. However, data regarding the effects of combined exercise training programs in patients with PH still remains limited.

AIM

To investigate the effects of combined exercise training programs on exercise capacity and quality of life in patients with PH.

METHODS

Our search included all available randomized controlled trials (RCTs) regarding combined aerobic, resistance and inspiratory training programs in patients with PH in 4 databases (Pubmed, PEDro, Embase, CINAHL) from 2012 to 2022. Five RCTs were included in the final analysis. Functional capacity, assessed by peak VO2 or 6-min walking test (6MWT), as well as quality of life, assessed by the SF-36 questionnaire, were set as the primary outcomes in our study.

RESULTS

Peak VO2 was measured in 4 out of the 5 RCTs while 6MWT was measured in all RCTs. Both indices of functional capacity were significantly increased in patients with PH who underwent combined exercise training compared to the controls in all of the included RCTs (P < 0.05). Quality of life was measured in 4 out of 5 RCTs. Although patients improved their quality of life in each group, however, only 2 RCTs demonstrated further improvement in patients performing combined training compared to controls.

CONCLUSION

By this systematic review, we have demonstrated that combined aerobic, resistance and inspiratory exercise training is safe and has beneficial effects on aerobic capacity and quality of life in patients with PH. Such exercise training regimen may be part of the therapeutic strategy of the syndrome.

The Emerging Therapeutic Role of Prostaglandin E2 Signaling in Pulmonary Hypertension

Mild-to-moderate pulmonary hypertension (PH) is a common complication of chronic obstructive pulmonary disease (COPD). It is characterized by narrowing and thickening of the pulmonary arteries, resulting in increased pulmonary vascular resistance (PVR) and ultimately leading to right ventricular dysfunction. Pulmonary vascular remodeling in COPD is the main reason for the increase of pulmonary artery pressure (PAP). The pathogenesis of PH in COPD is complex and multifactorial, involving chronic inflammation, hypoxia, and oxidative stress. To date, prostacyclin and its analogues are widely used to prevent PH progression in clinical. These drugs have potent anti-proliferative, anti-inflammatory, and stimulating endothelial regeneration properties, bringing therapeutic benefits to the slowing, stabilization, and even some reversal of vascular remodeling. As another well-known and extensively researched prostaglandins, prostaglandin E2 (PGE2) and its downstream signaling have been found to play an important role in various biological processes. Emerging evidence has revealed that PGE2 and its receptors (i.e., EP1-4) are involved in the regulation of pulmonary vascular homeostasis and remodeling. This review focuses on the research progress of the PGE2 signaling pathway in PH and discusses the possibility of treating PH based on the PGE2 signaling pathway.

Pulmonary Artery Denervation as a New Therapeutic Option for Pulmonary Hypertension: A Systematic Review and Meta-Analysis

Pulmonary hypertension (PH) is a progressive disease with a high morbidity and mortality. The treatment is based on the type of PH. Prognosis still remains poor despite the use of different medications. Pulmonary artery denervation (PADN) has been studied as a novel therapeutic option in these patients. PUBMED, EMBASE and COCHRANE databases were searched by 2 investigators until January 2023. Information was analyzed for the following outcomes: 6-minute walk distance (6MWD), mean pulmonary artery pressure, pulmonary vascular resistance and cardiac output. Subgroup analysis comparing pre and post PADN in different PH groups was done. Statistical analysis was performed with the Review Manager version 5.4. This meta- analysis included 6 controlled trials and 6 single-arm prospective studies with a total of 616 patients. Our pooled analysis showed a significant reduction in mean pulmonary artery pressure [WMD -6.51, 95% CI (-9.87, -3.15), p = 0.0001], pulmonary vascular resistance [WMD -3.69, 95% CI (-6.74, -0.64), p = 0.02] and increased cardiac output [WMD -0.37, 95% CI (0.08, 0.65), p = 0.01]. Subgroup analysis pre and post PADN demonstrated a significant improvement in 6MWD in the WHO group 1 [WMD 99.53, 95% CI (19.60, 179.47), p = 0.01], group 2 [WMD: 69.96, 95% CI (36.40, 103.51), p = < 0.0001] and group 4 [WMD: 99.54, 95% CI (21.80, 177.28), p = 0.01]. This meta-analysis supports PADN as a therapeutic option for patients with PH, regardless of group class. Further randomized trials are still needed to evaluate safety and efficacy.

Clinical characteristics and predictors of pulmonary hypertension in chronic obstructive pulmonary disease at different altitudes

BACKGROUND

Pulmonary hypertension (PH) is a common complication in patients with chronic obstructive pulmonary disease (COPD) and is closely associated with poor prognosis. However, studies on the predictors of PH in COPD patients are limited, especially in populations living at high altitude (HA).

OBJECTIVES

To investigate the differences in the clinical characteristics and predictors of patients with COPD/COPD and PH (COPD-PH) from low altitude (LA, 600 m) and HA (2200 m).

METHODS

We performed a cross-sectional survey of 228 COPD patients of Han nationality admitted to the respiratory department of Qinghai People's Hospital (N = 113) and West China Hospital of Sichuan University (N = 115) between March 2019 and June 2021. PH was defined as a pulmonary arterial systolic pressure (PASP) > 36 mmHg measured using transthoracic echocardiography (TTE).

RESULTS

The proportion of PH in COPD patients living at HA was higher than that in patients living at LA (60.2% vs. 31.3%). COPD-PH patients from HA showed significantly different in baseline characteristics, laboratory tests and pulmonary function test. Multivariate logistic regression analysis indicated that the predictors of PH in COPD patients were different between the HA and LA groups.

CONCLUSIONS

The COPD patients living at HA had a higher proportion of PH than those living at LA. At LA, increased B-type natriuretic peptide (BNP) and direct bilirubin (DB) were predictors for PH in COPD patients. However, at HA, increased DB was a predictor of PH in COPD patients.

Natural Products for the Treatment of Pulmonary Hypertension: Mechanism, Progress, and Future Opportunities

Pulmonary hypertension (PH) is a lethal disease due to the remodeling of pulmonary vessels. Its pathophysiological characteristics include increased pulmonary arterial pressure and pulmonary vascular resistance, leading to right heart failure and death. The pathological mechanism of PH is complex and includes inflammation, oxidative stress, vasoconstriction/diastolic imbalance, genetic factors, and ion channel abnormalities. Currently, many clinical drugs for the treatment of PH mainly play their role by relaxing pulmonary arteries, and the treatment effect is limited. Recent studies have shown that various natural products have unique therapeutic advantages for PH with complex pathological mechanisms owing to their multitarget characteristics and low toxicity. This review summarizes the main natural products and their pharmacological mechanisms in PH treatment to provide a useful reference for future research and development of new anti-PH drugs and their mechanisms.

The mechanism of programmed death and endoplasmic reticulum stress in pulmonary hypertension

Pulmonary hypertension (PH) was a cardiovascular disease with high morbidity and mortality. PH was a chronic disease with complicated pathogenesis and uncontrollable factors. PH was divided into five groups according to its pathogenesis and clinical manifestations. Although the treatment and diagnosis of PH has made great progress in the past ten years. However, the diagnosis and prognosis of the PAH had a great contrast, which was not conducive to the diagnosis and treatment of PH. If not treated properly, it will lead to right ventricular failure or even death. Therefore, it was necessary to explore the pathogenesis of PH. The problem we urgently need to solve was to find and develop drugs for the treatment of PH. We reviewed the PH articles in the past 10 years or so as well as systematically summarized the recent advance. We summarized the latest research on the key regulatory factors (pyroptosis, apoptosis, necroptosis, ferroptosis, and endoplasmic reticulum stress) involved in PH. To provide theoretical basis and basis for finding new therapeutic targets and research directions of PH.

Mechanistic and therapeutic perspectives of baicalin and baicalein on pulmonary hypertension: A comprehensive review

Pulmonary hypertension (PH) is a chronic and fatal disease, for which new therapeutic drugs and approaches are needed urgently. Baicalein and baicalin, the active compounds of the traditional Chinese medicine, Scutellaria baicalensis Georgi, exhibit a wide range of pharmacological activities. Numerous studies involving in vitro and in vivo models of PH have revealed that the treatment with baicalin and baicalein may be effective. This review summarizes the potential mechanisms driving the beneficial effects of baicalin and baicalein treatment on PH, including anti-inflammatory response, inhibition of pulmonary smooth muscle cell proliferation and endothelial-to-mesenchymal transformation, stabilization of the extracellular matrix, and mitigation of oxidative stress. The pharmacokinetics of these compounds have also been reviewed. The therapeutic potential of baicalin and baicalein warrants their continued study as natural treatments for PH.

Oxidative Stress and Antioxidative Therapy in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is clinically characterized by a progressive increase in pulmonary artery pressure, followed by right ventricular hypertrophy and subsequently right heart failure. The underlying mechanism of PAH includes endothelial dysfunction and intimal smooth muscle proliferation. Numerous studies have shown that oxidative stress is critical in the pathophysiology of PAH and involves changes in reactive oxygen species (ROS), reactive nitrogen (RNS), and nitric oxide (NO) signaling pathways. Disrupted ROS and NO signaling pathways cause the proliferation of pulmonary arterial endothelial cells (PAECs) and pulmonary vascular smooth muscle cells (PASMCs), resulting in DNA damage, metabolic abnormalities, and vascular remodeling. Antioxidant treatment has become a main area of research for the treatment of PAH. This review mainly introduces oxidative stress in the pathogenesis of PAH and antioxidative therapies and explains why targeting oxidative stress is a valid strategy for PAH treatment.

Target Nuclear Factor Erythroid 2-Related Factor 2 in Pulmonary Hypertension: Molecular Insight into Application

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor involved in maintaining redox balance and activates the expression of downstream antioxidant enzymes. Nrf2 has received wide attention considering its crucial role in oxidative and electrophilic stress. Large amounts of studies have demonstrated the protective role of Nrf2 activation in various pulmonary hypertension (pH) models. Additionally, various kinds of natural phytochemicals acting as Nrf2 activators prevent the development of pH and provide a novel and promising therapeutic insight for the treatment of pH. In the current review, we give a brief introduction of Nrf2 and focus on the role and mechanism of Nrf2 in the pathophysiology of pH and then review the relevant research of Nrf2 agonists in pH in both experimental research and clinical trials.

Melatonin Attenuates Dasatinib-Aggravated Hypoxic Pulmonary Hypertension via Inhibiting Pulmonary Vascular Remodeling

Dasatinib treatment is approved as first-line therapy for chronic myeloid leukemia. However, pulmonary hypertension (PH) is a highly morbid and often fatal side-effect of dasatinib, characterized by progressive pulmonary vascular remodeling. Melatonin exerts strong antioxidant capacity against the progression of cardiovascular system diseases. The present work aimed to investigate the effect of melatonin on dasatinib-aggravated hypoxic PH and explore its possible mechanisms. Dasatinib-aggravated rat experimental model of hypoxic PH was established by utilizing dasatinib under hypoxia. The results indicated that melatonin could attenuate dasatinib-aggravated pulmonary pressure and vascular remodeling in rats under hypoxia. Additionally, melatonin attenuated the activity of XO, the content of MDA, the expression of NOX4, and elevated the activity of CAT, GPx, and SOD, the expression of SOD2, which were caused by dasatinib under hypoxia. In vitro, dasatinib led to decreased LDH activity and production of NO in human pulmonary microvascular endothelial cells (HPMECs), moreover increased generation of ROS, and expression of NOX4 both in HPMECs and primary rat pulmonary arterial smooth muscle cells (PASMCs) under hypoxia. Dasatinib up-regulated the expression of cleaved caspase-3 and the ratio of apoptotic cells in HPMECs, and also elevated the percentage of S phase and the expression of Cyclin D1 in primary PASMCs under hypoxia. Melatonin ameliorated dasatinib-aggravated oxidative damage and apoptosis in HPMECs, meanwhile reduced oxidative stress level, proliferation, and repressed the stability of HIF1-α protein in PASMCs under hypoxia. In conclusion, melatonin significantly attenuates dasatinib-aggravated hypoxic PH by inhibiting pulmonary vascular remodeling in rats. The possible mechanisms involved protecting endothelial cells and inhibiting abnormal proliferation of smooth muscle cells. Our findings may suggest that melatonin has potential clinical value as a therapeutic approach to alleviate dasatinib-aggravated hypoxic PH.

Non-Coding RNA Networks in Pulmonary Hypertension

Non-coding RNAs (ncRNAs) are involved in various cellular processes. There are several ncRNA classes, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). The detailed roles of these molecules in pulmonary hypertension (PH) remain unclear. We systematically collected and reviewed reports describing the functions of ncRNAs (miRNAs, lncRNAs, and circRNAs) in PH through database retrieval and manual literature reading. The characteristics of identified articles, especially the experimental methods, were carefully reviewed. Furthermore, regulatory networks were constructed using ncRNAs and their interacting RNAs or genes. These data were extracted from studies on pulmonary arterial smooth muscle cells, pulmonary artery endothelial cells, and pulmonary artery fibroblasts. We included 14 lncRNAs, 1 circRNA, 74 miRNAs, and 110 mRNAs in the constructed networks. Using these networks, herein, we describe the current knowledge on the role of ncRNAs in PH. Moreover, these networks actively provide an improved understanding of the roles of ncRNAs in PH. The results of this study are crucial for the clinical application of ncRNAs.

The role of TGF-β or BMPR2 signaling pathway-related miRNA in pulmonary arterial hypertension and systemic sclerosis

Pulmonary arterial hypertension (PAH) is a severe complication of connective tissue disease (CTD), causing death in systemic sclerosis (SSc). The past decade has yielded many scientific insights into microRNA (miRNAs) in PAH and SSc. This growth of knowledge has well-illustrated the complexity of microRNA (miRNA)-based regulation of gene expression in PAH. However, few miRNA-related SSc-PAH were elucidated. This review firstly discusses the role of transforming growth factor-beta (TGF-β) signaling and bone morphogenetic protein receptor type II (BMPR2) in PAH and SSc. Secondly, the miRNAs relating to TGF-β and BMPR2 signaling pathways in PAH and SSc or merely PAH were subsequently summarized. Finally, future studies might develop early diagnostic biomarkers and target-oriented therapeutic strategies for SSc-PAH and PAH treatment.

Penetrance of Severe Pulmonary Arterial Hypertension in Response to Vascular Endothelial Growth Factor Receptor 2 Blockade in a Genetically Prone Rat Model Is Reduced by Female Sex

Background We have previously reported important strain differences in response to SU5416 (SU, a vascular endothelial growth factor receptor 2 inhibitor) in rats and have identified a specific colony of Sprague-Dawley rats that are hyperresponsive (SDHR) to SU alone and develop severe pulmonary arterial hypertension (PAH) with a single injection of SU, even in the absence of hypoxia. Interestingly, SDHR rats exhibit incomplete penetrance of the severe PAH phenotype with an "all-or-none" response to SU alone, which provides a unique opportunity to assess the influence of female sex and sex hormones on susceptibility to PAH after endothelial injury in a genetically prone model. Methods and Results SDHR rats were injected with SU (20 mg/kg SC) and, in the absence of hypoxia, 72% of male but only 27% of female rats developed severe PAH at 7 weeks, which was associated with persistent endothelial cell apoptosis. This sex difference in susceptibility for severe PAH was abolished by ovariectomy. Estradiol replacement, beginning 2 days before SU (prevention), inhibited lung endothelial cell apoptosis and completely abrogated severe PAH phenotype in both male and ovariectomized female rats, while progesterone was only protective in ovariectomized female rats. In contrast, delayed treatment of SDHR rats with established PAH with estradiol or progesterone (initiated at 4 weeks post-SU) failed to reduce lung endothelial cell apoptosis or improve PAH phenotype. Conclusions Female sex hormones markedly reduced susceptibility for the severe PAH phenotype in response to SU alone in a hyperresponsive rat strain by abolishing SU-induced endothelial cell apoptosis, but did not reverse severe PAH in established disease.

ROCK Inhibition as Potential Target for Treatment of Pulmonary Hypertension

Pulmonary hypertension (PH) is a cardiovascular disease caused by extensive vascular remodeling in the lungs, which ultimately leads to death in consequence of right ventricle (RV) failure. While current drugs for PH therapy address the sustained vasoconstriction, no agent effectively targets vascular cell proliferation and tissue inflammation. Rho-associated protein kinases (ROCKs) emerged in the last few decades as promising targets for PH therapy, since ROCK inhibitors demonstrated significant anti-remodeling and anti-inflammatory effects. In this review, current aspects of ROCK inhibition therapy are discussed in relation to the treatment of PH and RV dysfunction, from cell biology to preclinical and clinical studies.

Novel molecular insights and public omics data in pulmonary hypertension

Pulmonary hypertension is a rare disease with high morbidity and mortality which mainly affects women of reproductive age. Despite recent advances in understanding the pathogenesis of pulmonary hypertension, the high heterogeneity in the presentation of the disease among different patients makes it difficult to make an accurate diagnosis and to apply this knowledge to effective treatments. Therefore, new studies are required to focus on translational and personalized medicine to overcome the lack of specificity and efficacy of current management. Here, we review the majority of public databases storing 'omics' data of pulmonary hypertension studies, from animal models to human patients. Moreover, we review some of the new molecular mechanisms involved in the pathogenesis of pulmonary hypertension, including non-coding RNAs and the application of 'omics' data to understand this pathology, hoping that these new approaches will provide insights to guide the way to personalized diagnosis and treatment.

Identification of a potentially novel LncRNA-miRNA-mRNA competing endogenous RNA network in pulmonary arterial hypertension via integrated bioinformatic analysis

AIMS

Pulmonary arterial hypertension (PAH) is a fatal cardiovascular disease with a cancer-like phenotype. Competing endogenous RNA (ceRNA) networks extensively involve in its pathological processes. But rare ceRNA networks and profound molecular mechanisms have been revealed in PAH. The aim of this study was to illuminate the ceRNA networks in PAH.

MATERIALS AND METHODS

In this work, we have chosen the idiopathic PAH as an example. GSE15197 (mRNA) and GSE56914 (miRNA) from the Gene Expression Omnibus (GEO) were selected to explore key genes and novel ceRNA networks in PAH by a series of integrated bioinformatic analysis. To be more scientific, a part of pairs in identified ceRNA network were detected in hypoxia-induced HPASMCs. And the dual-luciferase assay was performed to certify the relationship between miRNAs and mRNAs.

KEY FINDINGS

Totally, 311 differentially expressed genes (DEGs) were identified and functional enrichment analysis illuminated that the majority of DEGs were enriched in proliferation, anti-apoptosis, inflammation and cancer-related pathways. And 10 hub genes were determined via Cytohubba after PPI network construction. Sequentially, with stepwise reverse prediction and pan-cancer co-expression analysis from mRNA to LncRNA in TargetScan, miRNet, ENCORI (Starbase V3.0) databases, a crucially ceRNA network was identified including 14 LncRNAs, 2 miRNAs, and 3 mRNAs. Further, in hypoxia-induced HPASMCs, the alterations of mRNAs, miRNAs and LncRNAs and their relationship were in accordance with the results we identified.

SIGNIFICANCE

Consequently, the unique hub genes and ceRNA network we proposed may advance our understanding of the molecular mechanisms in PAH.

Drug discovery focused on novel pathogenic proteins for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a fatal disease in which the wall thickening and narrowing of pulmonary microvessels progress due to complicated interactions among processes such as endothelial dysfunction, the proliferation of pulmonary artery smooth muscle cells (PASMCs) and adventitial fibrocytes, and inflammatory cell infiltration. Early diagnosis of patients with PAH is difficult and lung transplantation is the only last choice to save severely ill patients. However, the number of donors is limited. Many patients with PAH show rapid progression and a high degree of pulmonary arterial remodeling characterized by the abnormal proliferation of PASMCs, which makes treatment difficult even with multidrug therapy comprising pulmonary vasodilators. Thus, it is important to develop novel therapy targeting factors other than vasodilation, such as PASMC proliferation. In the development of PAH, inflammation and oxidative stress are deeply involved in its pathogenesis. Excessive proliferation and apoptosis resistance in PASMCs are key mechanisms underlying PAH. Based on those characteristics, we recently screened novel pathogenic proteins and have performed drug discovery targeting those proteins. To confirm the clinical significance of this, we used patient-derived blood samples to evaluate biomarker potential for diagnosis and prognosis. Moreover, we conducted high throughput screening and found several inhibitors of the pathogenic proteins. In this review, we introduce the recent progress on basic and clinical PAH research, focusing on the screening of pathogenic proteins and drug discovery.

Upregulation of miR-361-3p suppresses serotonin-induced proliferation in human pulmonary artery smooth muscle cells by targeting SERT

Background

Abnormal proliferation of pulmonary artery smooth muscle cells (PASMCs) is a key mechanism in pulmonary arterial hypertension (PAH). Serotonin (5-hydroxytryptamine, 5-HT) can induce abnormal proliferation of PASMCs. The role of miR-361-3p in serotonin-induced abnormal PASMCs proliferation remains unclear.

Methods

The miR-361-3p level was analyzed in plasma from PAH patients and normal controls and in human PASMCs (hPASMCs) using RT-PCR. The hPASMCs were transfected with an miR-361-3p mimic and then treated with serotonin. Untransfected hPASMCs were used as the control. Cell proliferation was evaluated using an MTS assay and 5-ethynyl-2′-deoxyuridine (EdU) staining. The cell cycle stages were evaluated using flow cytometry. The association between miR-361-3p and serotonin transporter (SERT) was determined using a luciferase reporter assay and anti-AGO2 RNA immunoprecipitation assay. The protein expression was evaluated via western blotting.

Results

The miR-361-3p level was lower in plasma from PAH patients than in plasma from the any of the normal control subjects. The mean pulmonary arterial pressure, pulmonary vascular resistance and pulmonary vascular resistance index were higher in PAH patients whose miR-361-3p level was lower than the median value for patients than in those whose miR-361-3p level was higher than the median. Serotonin treatment reduced miR-361-3p expression in the hPASMCs. MiR-361-3p overexpression suppressed cell proliferation, promoted apoptosis, induced G1 arrest, and decreased the phosphorylation level of ERK1/2 in serotonin-treated hPASMCs. SERT was identified as an miR-361-3p target. Its overexpression alleviated the effect of miR-361-3p overexpression on serotonin-induced hPASMC proliferation and upregulation of phosphorylated ERK1/2.

Conclusions

The miR-361-3p level is lower in the plasma of PAH patients. Upregulation of miR-361-3p suppresses serotonin-induced proliferation of hPASMCs by targeting SERT. Our results suggest that miR-361-3p is a potential therapeutic target in PAH.

The hallmarks of severe pulmonary arterial hypertension: the cancer hypothesis-ten years later

Severe forms of pulmonary arterial hypertension (PAH) are most frequently the consequence of a lumen-obliterating angiopathy. One pathobiological model is that the initial pulmonary vascular endothelial cell injury and apoptosis is followed by the evolution of phenotypically altered, apoptosis-resistant, proliferating cells and an inflammatory vascular immune response. Although there may be a vasoconstrictive disease component, the increased pulmonary vascular shear stress in established PAH is caused largely by the vascular wall pathology. In this review, we revisit the "quasi-malignancy concept" of severe PAH and examine to what extent the hallmarks of PAH can be compared with the hallmarks of cancer. The cancer model of severe PAH, based on the growth of abnormal vascular and bone marrow-derived cells, may enable the emergence of novel cell-based PAH treatment strategies.

Beyond the Lungs: Systemic Manifestations of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a disease characterized by progressive loss and remodeling of the pulmonary arteries, resulting in right heart failure and death. Until recently, PAH was seen as a disease restricted to the pulmonary circulation. However, there is growing evidence that patients with PAH also exhibit systemic vascular dysfunction, as evidenced by impaired brachial artery flow-mediated dilation, abnormal cerebral blood flow, skeletal myopathy, and intrinsic kidney disease. Although some of these anomalies are partially due to right ventricular insufficiency, recent data support a mechanistic link to the genetic and molecular events behind PAH pathogenesis. This review serves as an introduction to the major systemic findings in PAH and the evidence that supports a common mechanistic link with PAH pathophysiology. In addition, it discusses recent studies describing morphological changes in systemic vessels and the possible role of bronchopulmonary anastomoses in the development of plexogenic arteriopathy. On the basis of available evidence, we propose a paradigm in which metabolic abnormalities, genetic injury, and systemic vascular dysfunction contribute to systemic manifestations in PAH. This concept not only opens exciting research possibilities but also encourages clinicians to consider extrapulmonary manifestations in their management of patients with PAH.

Chemerin-9-induced contraction was enhanced through the upregulation of smooth muscle chemokine-like receptor 1 in isolated pulmonary artery of pulmonary arterial hypertensive rats

Chemerin is an adipocytokine having cardiovascular effects. Chemokine-like receptor 1 (CMKLR1) and chemokine (CC motif) receptor-like 2 (CCRL2) are chemerin receptors. Chemerin-9, an active fragment, causes contraction via smooth muscle CMKLR1 in isolated blood vessels. Pulmonary arterial hypertension (PAH) is a fatal disease resulting ultimately in right heart failure. To test the hypothesis that chemerin affects pulmonary artery (PA) resistance, we examined the effects of chemerin-9 on contractility of isolated PA from PAH rats. Wistar rats were injected with monocrotaline (MCT) for 2 weeks to make PAH rats (MCT rats). Control (Cont) rats received a saline injection. Chemerin-9-induced contraction of isolated intrapulmonary artery (IPA) from left lung was isometrically measured. Protein expression of CMKLR1 and CCRL2 in isolated left lung was determined by Western blotting. Localization of CMKLR1 in IPA of left lung was examined immunohistochemically. Chemerin-9-induced contraction was significantly enhanced in IPA from MCT compared with Cont rats. Protein expression of CMKLR1 was significantly elevated in isolated left lung from MCT compared with Cont rats, while protein expression of CCRL2, a decoy receptor, was significantly decreased. CMKLR1 was localized mainly in endothelium of IPA in Cont rats. The CMKLR1 expression was significantly decreased in endothelium of IPA in MCT rats, while it was significantly elevated in smooth muscle. The present study for the first time demonstrated that the enhanced chemerin-9-induced contraction of isolated IPA from MCT rats was at least partly caused by the increase of CMKLR1 in smooth muscle.

Targeting epigenetic mechanisms as an emerging therapeutic strategy in pulmonary hypertension disease

Pulmonary arterial hypertension (PAH) is a multifactorial cardiopulmonary disease characterized by an elevation of pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR), which can lead to right ventricular (RV) failure, multi-organ dysfunction, and ultimately to premature death. Despite the advances in molecular biology, the mechanisms underlying pulmonary hypertension (PH) remain unclear. Nowadays, there is no curative treatment for treating PH. Therefore, it is crucial to identify novel, specific therapeutic targets and to offer more effective treatments against the progression of PH. Increasing amounts of evidence suggest that epigenetic modification may play a critical role in the pathogenesis of PAH. In the presented paper, we provide an overview of the epigenetic mechanisms specifically, DNA methylation, histone acetylation, histone methylation, and ncRNAs. As the recent identification of new pharmacological drugs targeting these epigenetic mechanisms has opened new therapeutic avenues, we also discuss the importance of epigenetic-based therapies in the context of PH.

Efficacy and safety of tetramethylpyrazine phosphate on pulmonary hypertension: study protocol for a randomized controlled study

BACKGROUND

Tetramethylpyrazine (TMP), an active ingredient in the traditional Chinese herbal medicine Rhizoma Chuanxiong, has been used clinically for the prevention and treatment of cardiovascular disease. The benefits of TMP are largely attributed to its anti-oxidative and vasodilative properties. However, the efficacy of TMP in the treatment of pulmonary hypertension (PH) is unknown. We hypothesized that TMP may have a therapeutic effect in patients with PH.

METHODS/DESIGN

A randomized, single-blinded, clinical study with a TMP treatment group and a control group will be conducted to evaluate the efficacy and safety of TMP intervention in patients with PH. The recruitment target is 120 subjects meeting the following criteria: (i) at rest and at sea level, mean pulmonary artery pressure above 20 mmHg and pulmonary capillary wedge pressure below 15 mmHg; (ii) type 1 or 4 PH in the stable phase; (iii) age 15-70 years; (iv) 6-min walk distance between 100 and 450 m; (v) World Health Organization (WHO) functional classification of pulmonary hypertension of II, III, or IV. Subjects will be assigned randomly into two groups at a ratio of 1:2 (control:TMP). Both groups will receive routine treatment, and the treatment group will also receive oral TMP (100 mg) three times a day for 16 weeks. All patients will be followed up for 4, 8, 12, and 16 weeks; symptoms and patient compliance will be recorded.

DISCUSSION

We aimed to determine the efficacy and safety of TMP for the treatment of PH.

TRIAL REGISTRATION

Chinese Clinical Trial Register, ChiCTR1800018664. Registered on 2 October 2018.

Highlights from the ERS International Congress 2018: Assembly 13 - Pulmonary Vascular Diseases

The 2018 European Respiratory Society (ERS) International Congress in Paris, France, highlighted the subject of pulmonary vascular disease (PVD). 2018 was an exciting year for the PVD community as it was the first ERS International Congress since the formation of Assembly 13, which is dedicated to PVD, pulmonary embolism and the right ventricle. This article aims to summarise the high-quality studies presented at the 2018 Congress into four subject areas: the use of risk stratification in pulmonary arterial hypertension, the molecular mechanisms and treatment of pulmonary hypertension (PH), understanding and improving the right ventricle in PH, and finally, advances in the field of acute pulmonary embolus.

Identification of Novel Therapeutic Targets for Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are fatal diseases; however, their pathogenesis still remains to be elucidated. We have recently screened novel pathogenic molecules and have performed drug discovery targeting those molecules. Pulmonary artery smooth muscle cells (PASMCs) in patients with PAH (PAH-PASMCs) have high proliferative properties like cancer cells, which leads to thickening and narrowing of distal pulmonary arteries. Thus, we conducted a comprehensive analysis of PAH-PASMCs and lung tissues to search for novel pathogenic proteins. We validated the pathogenic role of the selected proteins by using tissue-specific knockout mice. To confirm its clinical significance, we used patient-derived blood samples to evaluate the potential as a biomarker for diagnosis and prognosis. Finally, we conducted a high throughput screening and found inhibitors for the pathogenic proteins.

AOS ameliorates monocrotaline-induced pulmonary hypertension by restraining the activation of P-selectin/p38MAPK/NF-κB pathway in rats

Perivascular inflammation, vascular luminal area reduction and hemodynamics changes are important pathophysiologic bases of pulmonary hypertension (PH). In this study, PH was induced by an intraperitoneal single injection of monocrotaline (MCT, 60 mg/kg). Alginate oligosaccharides (AOS), one of the most famous marine drugs, provided protections in the perivascular inflammation, vascular luminal area reduction and hemodynamics changes of the PH rat induced by MCT. The downregulation of P-selectin plays an important role in the protective effects of AOS against MCT induced PH. The results showed that the treatment with AOS (5, 10, or 20 mg/kg) dose-dependently decreased the expression of P-selectin in serum, pulmonary tissue and pulmonary artery of MCT-induced pulmonary arterial hypertension rats. What's more, the study showed that the protective effects were mediated by the inhibition of p38MAPK/NF-κB pathway, which was caused by reducing the p-p38MAPK protein expression, IκBα degradation and nuclear transcription of NF-κB protein in the pulmonary artery of MCT-induced PH rats. These findings provided an alternative potent medicine for the prevention and therapy of PH.