Search

Background: Pathogenic concepts of right ventricular (RV) failure in pulmonary arterial hypertension focus on a critical loss of microvasculature. However, the methods underpinning prior studies did not take into account the 3-dimensional (3D) aspects of cardiac tissue, making accurate quantification difficult. We applied deep-tissue imaging to the pressure-overloaded RV to uncover the 3D properties of the microvascular network and determine whether deficient microvascular adaptation contributes to RV failure., Methods: Heart sections measuring 250-µm-thick were obtained from mice after pulmonary artery banding (PAB) or debanding PAB surgery and properties of the RV microvascular network were assessed using 3D imaging and quantification. Human heart tissues harvested at the time of transplantation from pulmonary arterial hypertension cases were compared with tissues from control cases with normal RV function., Results: Longitudinal 3D assessment of PAB mouse hearts uncovered complex microvascular remodeling characterized by tortuous, shorter, thicker, highly branched vessels, and overall preserved microvascular density. This remodeling process was reversible in debanding PAB mice in which the RV function recovers over time. The remodeled microvasculature tightly wrapped around the hypertrophied cardiomyocytes to maintain a stable contact surface to cardiomyocytes as an adaptation to RV pressure overload, even in end-stage RV failure. However, microvasculature-cardiomyocyte contact was impaired in areas with interstitial fibrosis where cardiomyocytes displayed signs of hypoxia. Similar to PAB animals, microvascular density in the RV was preserved in patients with end-stage pulmonary arterial hypertension, and microvascular architectural changes appeared to vary by etiology, with patients with pulmonary veno-occlusive disease displaying a lack of microvascular complexity with uniformly short segments., Conclusions: 3D deep tissue imaging of the failing RV in PAB mice, pulmonary hypertension rats, and patients with pulmonary arterial hypertension reveals complex microvascular changes to preserve the microvascular density and maintain a stable microvascular-cardiomyocyte contact. Our studies provide a novel framework to understand microvascular adaptation in the pressure-overloaded RV that focuses on cell-cell interaction and goes beyond the concept of capillary rarefaction., Competing Interests: Disclosures None.

This study analyzed microarray data of right ventricular (RV) tissue from rats exposed to pulmonary embolism to understand the initial dynamic transcriptional response to mechanical stress and compare it with experimental pulmonary hypertension (PH) models. The dataset included samples harvested from 55 rats at 11 different time points or RV locations. We performed principal component analysis (PCA) to explore clusters based on spatiotemporal gene expression. Relevant pathways were identified from fast gene set enrichment analysis using PCA coefficients. The RV transcriptomic signature was measured over several time points, ranging from hours to weeks after an acute increase in mechanical stress, and was found to be highly dependent on the severity of the initial insult. Pathways enriched in the RV outflow tracts of rats at 6 weeks after severe PE share many commonalities with experimental PH models, but the transcriptomic signature at the RV apex resembles control tissue. The severity of the initial pressure overload determines the trajectory of the transcriptomic response independent of the final afterload, but this depends on the location where the tissue is biopsied. Chronic RV pressure overload due to PH appears to progress toward similar transcriptomic endpoints.

Background: Pulmonary hypertension (PH) can occur as a complication of schistosomiasis. In humans, schistosomiasis-PH persists despite antihelminthic therapy and parasite eradication. We hypothesized that persistent disease arises as a consequence of exposure repetition., Methods: Following intraperitoneal sensitization, mice were experimentally exposed to Schistosoma eggs by intravenous injection, either once or three times repeatedly. The phenotype was characterized by right heart catheterization and tissue analysis., Results: Following intraperitoneal sensitization, a single intravenous Schistosoma egg exposure resulted in a PH phenotype that peaked at 7-14 days, followed by spontaneous resolution. Three sequential exposures resulted in a persistent PH phenotype. Inflammatory cytokines were not significantly different between mice exposed to one or three egg doses, but there was an increase in perivascular fibrosis in those who received three egg doses. Significant perivascular fibrosis was also observed in autopsy specimens from patients who died of this condition., Conclusions: Repeatedly exposing mice to schistosomiasis causes a persistent PH phenotype, accompanied by perivascular fibrosis. Perivascular fibrosis may contribute to the persistent schistosomiasis-PH observed in humans with this disease., (© 2023 The Author(s).)

Circular RNAs (circRNAs) are endogenous, covalently circularised, non-protein-coding RNAs generated from back-splicing. Most circRNAs are very stable, highly conserved, and expressed in a tissue-, cell- and developmental stage-specific manner. circRNAs play a significant role in various biological processes, such as regulation of gene expression and protein translation via sponging of microRNAs and binding with RNA-binding proteins. circRNAs have become a topic of great interest in research due to their close link with the development of various diseases. Their high stability, conservation and abundance in body fluids make them promising biomarkers for many diseases. A growing body of evidence suggests that aberrant expression of circRNAs and their targets plays a crucial role in pulmonary vascular remodelling and pulmonary arterial hypertension (group 1) as well as other forms (groups 3 and 4) of pulmonary hypertension (PH). Here we discuss the roles and molecular mechanisms of circRNAs in the pathogenesis of pulmonary vascular remodelling and PH. We also highlight the therapeutic and biomarker potential of circRNAs in PH., Competing Interests: Conflict of interest: The authors have no conflicts of interest to declare., (Copyright ©The authors 2022. For reproduction rights and permissions contact permissions@ersnet.org.)

Pulmonary arterial hypertension (PAH) is a debilitating multifactorial disease characterized by progressive pulmonary vascular remodeling, elevated pulmonary arterial pressure, and pulmonary vascular resistance, resulting in right ventricular failure and subsequent death. Current available therapies do not reverse the disease, resulting in a persistent high morbidity and mortality. Thus, there is an urgent unmet medical need for novel effective therapies to better treat patients with PAH. Over the past few years, enthusiastic attempts have been made to identify novel effective therapies that address the essential roots of PAH with targeting key signaling pathways in both preclinical models and patients with PAH. This review aims to discuss the most emerging and promising therapeutic interventions in PAH pathogenesis., Competing Interests: Conflict of interest statement E.S. has served as scientific adviser for Selten Pharma, Inc., Vivus (modest). E.S. is listed as inventor on patent applications Use of FK506 for the Treatment of Pulmonary Arterial Hypertension (Serial No 61/481317) and Enzastaurin and Fragile Histidine Trial (FHIT) Increasing Agents for the Treatment of Pulmonary Hypertension (PCT/US2018/033533). M.K.A and K.I. have no conflicts of interest to declare., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

No prior proteomic screening study has centred on the right ventricle (RV) in pulmonary arterial hypertension (PAH). This study investigates the circulating proteomic profile associated with right heart maladaptive phenotype (RHMP) in PAH.Plasma proteomic profiling was performed using multiplex immunoassay in 121 (discovery cohort) and 76 (validation cohort) PAH patients. The association between proteomic markers and RHMP, defined by the Mayo right heart score (combining RV strain, New York Heart Association (NYHA) class and N-terminal pro-brain natriuretic peptide (NT-proBNP)) and Stanford score (RV end-systolic remodelling index, NYHA class and NT-proBNP), was assessed by partial least squares regression. Biomarker expression was measured in RV samples from PAH patients and controls, and pulmonary artery banding (PAB) mice.High levels of hepatocyte growth factor (HGF), stem cell growth factor-β, nerve growth factor and stromal derived factor-1 were associated with worse Mayo and Stanford scores independently from pulmonary resistance or pressure in both cohorts (the validation cohort had more severe disease features: lower cardiac index and higher NT-proBNP). In both cohorts, HGF added value to the REVEAL score in the prediction of death, transplant or hospitalisation at 3 years. RV expression levels of HGF and its receptor c-Met were higher in end-stage PAH patients than controls, and in PAB mice than shams.High plasma HGF levels are associated with RHMP and predictive of 3-year clinical worsening. Both HGF and c-Met RV expression levels are increased in PAH. Assessing plasma HGF levels might identify patients at risk of heart failure who warrant closer follow-up and intensified therapy., Competing Interests: Conflict of interest: M. Amsallem has received a 2016 Young Investigator Seed Grant from the Vera Moulton Wall Center at Stanford, a 2019–2020 Stanford Maternal and Child Health Research Institute research seed grant, a research grant from Actelion-Janssen and speaker fees from Bayer. Conflict of interest: A.J. Sweatt has nothing to disclose. Conflict of interest: J. Arthur Ataam has nothing to disclose. Conflict of interest: J. Guihaire has nothing to disclose. Conflict of interest: F. Lecerf has nothing to disclose. Conflict of interest: M. Lambert has nothing to disclose. Conflict of interest: M.R. Ghigna has nothing to disclose. Conflict of interest: M.K. Ali has nothing to disclose. Conflict of interest: Y. Mao has nothing to disclose. Conflict of interest: E. Fadel has nothing to disclose. Conflict of interest: M. Rabinovitch has nothing to disclose. Conflict of interest: V. de Jesus Perez has nothing to disclose. Conflict of interest: E. Spiekerkoetter is funded by Stanford Cardiovascular Institute, National Heart Lung Blood Institute (NHLBI) at the National Institute of Health (NIH) grant R01 HL128734 and Department of Defense grant PR161256. Conflict of interest: O. Mercier has been supported by a public grant overseen by the French National Research Agency as part of the second Investissement d'Avenir program (ANR-15-RHUS-0002). Conflict of interest: F. Haddad has received research grants from Actelion-Janssen and Philips. Conflict of interest: R.T. Zamanian has nothing to disclose., (Copyright ©ERS 2021.)

Background: Pulmonary arterial hypertension (PAH) is a fatal disease characterized by profound vascular remodeling in which pulmonary arteries narrow because of medial thickening and occlusion by neointimal lesions, resulting in elevated pulmonary vascular resistance and right heart failure. Therapies targeting the neointima would represent a significant advance in PAH treatment; however, our understanding of the cellular events driving neointima formation, and the molecular pathways that control them, remains limited., Methods: We comprehensively map the stepwise remodeling of pulmonary arteries in a robust, chronic inflammatory mouse model of pulmonary hypertension. This model demonstrates pathological features of the human disease, including increased right ventricular pressures, medial thickening, neointimal lesion formation, elastin breakdown, increased anastomosis within the bronchial circulation, and perivascular inflammation. Using genetic lineage tracing, clonal analysis, multiplexed in situ hybridization, immunostaining, deep confocal imaging, and staged pharmacological inhibition, we define the cell behaviors underlying each stage of vascular remodeling and identify a pathway required for neointima formation., Results: Neointima arises from smooth muscle cells (SMCs) and not endothelium. Medial SMCs proliferate broadly to thicken the media, after which a small number of SMCs are selected to establish the neointima. These neointimal founder cells subsequently undergoing massive clonal expansion to form occlusive neointimal lesions. The normal pulmonary artery SMC population is heterogeneous, and we identify a Notch3-marked minority subset of SMCs as the major neointimal cell of origin. Notch signaling is specifically required for the selection of neointimal founder cells, and Notch inhibition significantly improves pulmonary artery pressure in animals with pulmonary hypertension., Conclusions: This work describes the first nongenetically driven murine model of pulmonary hypertension (PH) that generates robust and diffuse occlusive neointimal lesions across the pulmonary vascular bed and does so in a stereotyped timeframe. We uncover distinct cellular and molecular mechanisms underlying medial thickening and neointima formation and highlight novel transcriptional, behavioral, and pathogenic heterogeneity within pulmonary artery SMCs. In this model, inflammation is sufficient to generate characteristic vascular pathologies and physiological measures of human PAH. We hope that identifying the molecular cues regulating each stage of vascular remodeling will open new avenues for therapeutic advancements in the treatment of PAH.

Pulmonary arterial hypertension (PAH) is a pulmonary vasculopathy that causes right ventricular dysfunction and exercise limitation and progresses to death. New findings from translational studies have suggested alternative pathways for treatment. These avenues include sex hormones, genetic abnormalities and DNA damage, elastase inhibition, metabolic dysfunction, cellular therapies, and anti-inflammatory approaches. Both novel and repurposed compounds with rationale from preclinical experimental models and human cells are now in clinical trials in patients with PAH. Findings from these studies will elucidate the pathobiology of PAH and may result in clinically important improvements in outcome.

The following review summarizes the pro-con debate about current controversies regarding the pathogenesis of pulmonary arterial hypertension (PAH) that took place at the American Thoracic Society Conference in May 2017. Leaders in the field of PAH research discussed the importance of the immune system, the role of hemodynamic stress and endothelial apoptosis, as well as bone morphogenetic protein receptor-2 signaling in PAH pathogenesis. Whereas this summary does not intend to resolve obvious conflicts in opinion, we hope that the presented arguments entice further discussions and draw a new generation of enthusiastic researchers into this vibrant field of science to bridge existing gaps for a better understanding and therapy of this fatal disease.

Background: We aimed to provide a set of previously reported PAH-associated missense and nonsense variants, and evaluate the pathogenicity of those variants., Methods: The Human Gene Mutation Database, PubMed, and Google Scholar were searched for previously reported PAH-associated genes and variants. Thereafter, both exome sequencing project and exome aggregation consortium as background population searched for previously reported PAH-associated missense and nonsense variants. The pathogenicity of previously reported PAH-associated missense variants evaluated by using four in silico prediction tools., Results: In total, 14 PAH-associated genes and 180 missense and nonsense variants were gathered. The BMPR2, the most frequent reported gene, encompasses 135 of 180 missense and nonsense variants. The exome sequencing project comprised 9, and the exome aggregation consortium counted 25 of 180 PAH-associated missense and nonsense variants. The TOPBP1 and ENG genes are unlikely to be the monogenic cause of PAH pathogenesis based on allele frequency in background population and prediction analysis., Conclusion: This is the first evaluation of previously reported PAH-associated missense and nonsense variants. The BMPR2 identified as the major gene out of 14 PAH-associated genes. Based on findings, the ENG and TOPBP1 gene are not likely to be the monogenic cause of PAH., (© 2018 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals, Inc.)

Pulmonary arterial hypertension (PAH) is a devastating disease characterised by occlusive pulmonary vasculopathy. Activation of bone morphogenetic protein receptor 2 (BMPR2) signalling by FK506 (tacrolimus) reverses occlusive vasculopathy in rodent PAH models. Here, we determined the safety and tolerability of low-level FK506 therapy in stable PAH patients.We performed a randomised, double-blind, placebo-controlled, 16-week, single-centre, phase IIa trial in PAH patients with New York Heart Association functional class II/III symptoms using three FK506 target levels (<2, 2-3 and 3-5 ng·mL -1 ). 23 patients were randomised and 20 patients completed the trial.FK506 was generally well tolerated, with nausea/diarrhoea being the most commonly reported adverse event and no observation of line infections in patients on intravenous prostacyclin therapy. PAH patients had significantly lower BMPR2 expression in peripheral blood mononuclear cells versus healthy controls (n=13; p=0.005), which improved after FK506 treatment. While we observed that some patients responded with a pronounced increase in BMPR2 expression as well as improvement in 6-min walk distance, and serological and echocardiographic parameters of heart failure, these changes were not significant.Low-level FK506 is well tolerated and increases BMPR2 in subsets of PAH patients. These results support the study of FK506 in a phase IIb efficacy trial., Competing Interests: Conflict of interest: Disclosures can be found alongside this article at erj.ersjournals.com, (Copyright ©ERS 2017.)

Rationale: Pulmonary arterial hypertension is characterized by endothelial dysfunction, impaired bone morphogenetic protein receptor 2 (BMPR2) signaling, and increased elastase activity. Synthetic elastase inhibitors reverse experimental pulmonary hypertension but cause hepatotoxicity in clinical studies. The endogenous elastase inhibitor elafin attenuates hypoxic pulmonary hypertension in mice, but its potential to improve endothelial function and BMPR2 signaling, and to reverse severe experimental pulmonary hypertension or vascular pathology in the human disease was unknown., Objectives: To assess elafin-mediated regression of pulmonary vascular pathology in rats and in lung explants from patients with pulmonary hypertension. To determine if elafin amplifies BMPR2 signaling in pulmonary artery endothelial cells and to elucidate the underlying mechanism., Methods: Rats with pulmonary hypertension induced by vascular endothelial growth factor receptor blockade and hypoxia (Sugen/hypoxia) as well as lung organ cultures from patients with pulmonary hypertension were used to assess elafin-mediated reversibility of pulmonary vascular disease. Pulmonary arterial endothelial cells from patients and control subjects were used to determine the efficacy and mechanism of elafin-mediated BMPR2 signaling., Measurements and Main Results: In Sugen/hypoxia rats, elafin reduced elastase activity and reversed pulmonary hypertension, judged by regression of right ventricular systolic pressure and hypertrophy and pulmonary artery occlusive changes. Elafin improved endothelial function by increasing apelin, a BMPR2 target. Elafin induced apoptosis in human pulmonary arterial smooth muscle cells and decreased neointimal lesions in lung organ culture. In normal and patient pulmonary artery endothelial cells, elafin promoted angiogenesis by increasing pSMAD-dependent and -independent BMPR2 signaling. This was linked mechanistically to augmented interaction of BMPR2 with caveolin-1 via elafin-mediated stabilization of endothelial surface caveolin-1., Conclusions: Elafin reverses obliterative changes in pulmonary arteries via elastase inhibition and caveolin-1-dependent amplification of BMPR2 signaling.

Pulmonary arterial hypertension (PAH) is a life-threatening disorder that is associated with elevated pulmonary pressures and right heart failure resulting from progressive loss and thickening of small pulmonary arteries. Despite their ability to improve symptoms, current therapies fail to prevent disease progression, leaving lung transplantation as the only therapy in end-stage PAH. To overcome the limitations of current therapies, there is an active search for disease-modifying agents capable of altering the natural history of, and improving clinical outcomes in, PAH. The Wnt signaling pathways have emerged as attractive treatment targets in PAH given their role in the preservation of pulmonary vascular homeostasis and the recent development of Wnt-specific compounds and biological therapies capable of modulating pathway activity. In this review, we summarize the literature describing the role of Wnt signaling in the pulmonary circulation and discuss promising advances in the field of Wnt therapeutics that could lead to novel clinical therapies capable of preventing and/or reversing pulmonary vascular pathology in patients with this devastating disease., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

During the past 2 decades, there has been a tremendous evolution in the evaluation and care of patients with pulmonary arterial hypertension (PAH). The introduction of targeted PAH therapy consisting of prostacyclin and its analogs, endothelin antagonists, phosphodiesterase-5 inhibitors, and now a soluble guanylate cyclase activator have increased therapeutic options and potentially reduced morbidity and mortality; yet, none of the current therapies have been curative. Current clinical management of PAH has become more complex given the focus on early diagnosis, an increased number of available therapeutics within each mechanistic class, and the emergence of clinically challenging scenarios such as perioperative care. Efforts to standardize the clinical care of patients with PAH have led to the formation of multidisciplinary PAH tertiary care programs that strive to offer medical care based on peer-reviewed evidence-based, and expert consensus guidelines. Furthermore, these tertiary PAH centers often support clinical and basic science research programs to gain novel insights into the pathogenesis of PAH with the goal to improve the clinical management of this devastating disease. In this article, we discuss the clinical approach and management of PAH from the perspective of a single US-based academic institution. We provide an overview of currently available clinical guidelines and offer some insight into how we approach current controversies in clinical management of certain patient subsets. We conclude with an overview of our program structure and a perspective on research and the role of a tertiary PAH center in contributing new knowledge to the field., (© 2014 American Heart Association, Inc.)

Idiopathic pulmonary arterial hypertension (PAH [IPAH]) is an insidious and potentially fatal disease linked to a mutation or reduced expression of bone morphogenetic protein receptor 2 (BMPR2). Because intravascular inflammatory cells are recruited in IPAH pathogenesis, we hypothesized that reduced BMPR2 enhances production of the potent chemokine granulocyte macrophage colony-stimulating factor (GM-CSF) in response to an inflammatory perturbation. When human pulmonary artery (PA) endothelial cells deficient in BMPR2 were stimulated with tumor necrosis factor (TNF), a twofold increase in GM-CSF was observed and related to enhanced messenger RNA (mRNA) translation. The mechanism was associated with disruption of stress granule formation. Specifically, loss of BMPR2 induced prolonged phospho-p38 mitogen-activated protein kinase (MAPK) in response to TNF, and this increased GADD34-PP1 phosphatase activity, dephosphorylating eukaryotic translation initiation factor (eIF2α), and derepressing GM-CSF mRNA translation. Lungs from IPAH patients versus unused donor controls revealed heightened PA expression of GM-CSF co-distributing with increased TNF and expanded populations of hematopoietic and endothelial GM-CSF receptor α (GM-CSFRα)-positive cells. Moreover, a 3-wk infusion of GM-CSF in mice increased hypoxia-induced PAH, in association with increased perivascular macrophages and muscularized distal arteries, whereas blockade of GM-CSF repressed these features. Thus, reduced BMPR2 can subvert a stress granule response, heighten GM-CSF mRNA translation, increase inflammatory cell recruitment, and exacerbate PAH.

Dysfunctional bone morphogenetic protein receptor-2 (BMPR2) signaling is implicated in the pathogenesis of pulmonary arterial hypertension (PAH). We used a transcriptional high-throughput luciferase reporter assay to screen 3,756 FDA-approved drugs and bioactive compounds for induction of BMPR2 signaling. The best response was achieved with FK506 (tacrolimus), via a dual mechanism of action as a calcineurin inhibitor that also binds FK-binding protein-12 (FKBP12), a repressor of BMP signaling. FK506 released FKBP12 from type I receptors activin receptor-like kinase 1 (ALK1), ALK2, and ALK3 and activated downstream SMAD1/5 and MAPK signaling and ID1 gene regulation in a manner superior to the calcineurin inhibitor cyclosporine and the FKBP12 ligand rapamycin. In pulmonary artery endothelial cells (ECs) from patients with idiopathic PAH, low-dose FK506 reversed dysfunctional BMPR2 signaling. In mice with conditional Bmpr2 deletion in ECs, low-dose FK506 prevented exaggerated chronic hypoxic PAH associated with induction of EC targets of BMP signaling, such as apelin. Low-dose FK506 also reversed severe PAH in rats with medial hypertrophy following monocrotaline and in rats with neointima formation following VEGF receptor blockade and chronic hypoxia. Our studies indicate that low-dose FK506 could be useful in the treatment of PAH.

Pulmonary arterial hypertension (PAH) is a disease characterized by increased pulmonary pressures and chronic right heart failure. Therapies for moderate and severe PAH include subcutaneous (SQ) and intravenous (IV) prostanoids that improve symptoms and quality of life. However, treatment compliance can be limited by severe side effects and complications related to methods of drug administration. Inhaled prostanoids, which offer the advantage of direct delivery of the drug to the pulmonary circulation without need for invasive approaches, may serve as an alternative for patients unable to tolerate SQ/IV therapy. In this retrospective cohort study we collected clinical, hemodynamic, and functional data from 18 clinically stable patients with World Health Organization group I PAH seen in 6 large national PAH centers before and after transitioning to inhaled treprostinil from IV/SQ prostanoids. Before transition 15 patients had been receiving IV or SQ treprostinil (mean dose 73 ng/kg/min) and 3 patients had been on IV epoprostenol (mean dose 10 ng/kg/min) for an average duration of 113 ± 80 months. Although most patients who transitioned to inhaled treprostinil demonstrated no statistically significant worsening of hemodynamics or 6-minute walk distance, a minority demonstrated worsening of New York Heart Association functional class over a 7-month period. In conclusion, although transition of patients from IV/SQ prostanoids to inhaled treprostinil appears to be well tolerated in clinically stable patients, they should remain closely monitored for signs of clinical decompensation., (Copyright © 2012. Published by Elsevier Inc.)

Previously, we reported that murine gammaherpesvirus-68 (M1-MHV-68) induces pulmonary artery (PA) neointimal lesions in S100A4-overexpressing, but not in wild-type (C57), mice. Lesions were associated with heightened lung elastase activity and PA elastin degradation. We now investigate a direct relationship between elastase and PA neointimal lesions, the nature and source of the enzyme, and its presence in clinical disease. We found an association exists between the percentage of PAs with neointimal lesions and elastin fragmentation in S100A4 mice 6 months after viral infection. Confocal microscopy documented the heightened susceptibility of S100A4 versus C57 PA elastin to degradation by elastase. A transient increase in lung elastase activity occurs in S100A4 mice, 7 days after M1-MHV-68, unrelated to inflammation or viral load and before neointimal lesions. Administration of recombinant elafin, an elastase-specific inhibitor, ameliorates early increases in serine elastase and attenuates later development of neointimal lesions. Neutrophils are the source of elevated elastase (NE) in the S100A4 lung, and NE mRNA and protein levels are greater in PA smooth muscle cells (SMC) from S100A4 mice than from C57 mice. Furthermore, elevated NE is observed in cultured PA SMC from idiopathic PA hypertension versus that in control lungs and localizes to neointimal lesions. Thus, PA SMC produce NE, and heightened production and activity of NE is linked to experimental and clinical pulmonary vascular disease., (Copyright © 2011 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Novel treatments, such as prostanoids or endothelin receptor antagonists, have been introduced for various forms of pulmonary arterial hypertension, but the long-term effects of these treatments on portopulmonary hypertension (PPHT) are unknown. In a retrospective analysis, the present authors assessed the safety and efficacy of inhaled iloprost, a prostacyclin analogue, and bosentan, an endothelin receptor antagonist, in patients with PPHT. In total, 31 consecutive patients with Child class A or B cirrhosis and severe PPHT were treated for up to 3 yrs with either inhaled iloprost (n = 13) or bosentan (n = 18), and the effects on exercise capacity, haemodynamics and survival were evaluated. In the iloprost group, the survival rates at 1, 2 and 3 yrs were 77, 62 and 46%, respectively. In the bosentan group, the respective survival rates were 94, 89 and 89%. Event-free survival rates, i.e. survival without transplantation, right heart failure or clinical worsening requiring the introduction of a new treatment for pulmonary hypertension, was also significantly better in the bosentan group. Bosentan had significantly better effects than inhaled iloprost on exercise capacity, as determined by the 6-min walk test, as well as on haemodynamics. Both treatments proved to be safe, especially in regards of liver function. In the present series of patients with well-preserved liver function and severe portopulmonary hypertension, treatment with both inhaled iloprost and bosentan appeared to be safe. Patients treated with bosentan had higher survival rates, but prospective controlled studies are required to confirm these findings.

Combination therapy may improve outcome in patients with severe pulmonary arterial hypertension (PAH). PAH patients were treated according to a goal-oriented therapeutic strategy. Patients who did not reach the treatment goals with monotherapy received combination treatment according to a predefined strategy, including bosentan, sildenafil and inhaled iloprost. Intravenous iloprost and lung transplantation were reserved for treatment failures. End points were overall survival, transplantation-free survival, and survival free from transplantation and intravenous prostanoid treatment. Between January 2002 and December 2004, 123 consecutive patients with PAH were treated according to the novel approach. Survival at 1, 2 and 3 yrs was 93.0, 83.1 and 79.9%, respectively, which was significantly better than the survival of a historical control group, as well as the expected survival. Compared to the historical control group, the use of combination treatment also significantly improved the combined end point of death, lung transplantation and need for intravenous iloprost treatment. In conclusion, a therapeutic approach utilising combinations of bosentan, sildenafil and inhaled iloprost in conjunction with a goal-oriented treatment strategy provides acceptable long-term results in patients with severe pulmonary arterial hypertension, and reduces the need for intravenous prostaglandin treatment and lung transplantation.

Transgenic mice overexpressing the calcium binding protein, S100A4/Mts1, occasionally develop severe pulmonary vascular obstructive disease. To understand what underlies this propensity, we compared the pulmonary vascular hemodynamic and structural features of S100A4/Mts1 with control C57Bl/6 mice at baseline, following a 2-week exposure to chronic hypoxia, and after 1 and 3 months "recovery" in room air. S100A4/Mts1 mice had greater right ventricular systolic pressure and right ventricular hypertrophy at baseline, which increased further with chronic hypoxia and was sustained after 3 months "recovery" in room air. These findings correlated with a heightened response to acute hypoxia and failure to vasodilate with nitric oxide or oxygen. S100A4/Mts1 mice, when compared with C57Bl/6 mice, also had impaired cardiac function judged by reduced ventricular elastance and decreased cardiac output. Despite higher right ventricular systolic pressures with chronic hypoxia, S100A4/Mts1 mice did not develop more severe PVD, but in contrast to C57Bl/6 mice, these features did not regress on return to room air. Microarray analysis of lung tissue identified a number of genes differentially upregulated in S100A4/Mts1 versus control mice. One of these, fibulin-5, is a matrix component necessary for normal elastin fiber assembly. Fibulin-5 was localized to pulmonary arteries and associated with thickened elastic laminae. This feature could underlie attenuation of pulmonary vascular changes in response to elevated pressure, as well as impaired reversibility.

Heightened expression of the S100 calcium-binding protein, S100A4/Mts1, is observed in pulmonary vascular disease. Loss of serotonin (5-hydroxytryptamine [5-HT]) receptors or of the serotonin transporter (SERT) attenuates pulmonary hypertension in animals, and polymorphisms causing gain of SERT function are linked to clinical pulmonary vascular disease. Because 5-HT induces release of S100beta, we investigated the codependence of 5-HT receptors and SERT in regulating S100A4/Mts1 in human pulmonary artery smooth muscle cells (hPA-SMC). 5-HT elevated S100A4/Mts1 mRNA levels and increased S100A4/Mts1 protein in hPA-SMC lysates and culture media. S100A4/Mts1 in the culture media stimulated proliferation and migration of hPA-SMC in a manner dependent on the receptor for advanced glycation end products. Treatment with SB224289 (selective antagonist of 5-HT1B), fluoxetine (SERT inhibitor), SERT RNA-interference, and iproniazid (monoamine oxidase-A inhibitor), blocked 5-HT-induced S100A4/Mts1. 5-HT signaling mediated phosphorylation (p) of extracellular signal-regulated kinase 1/2 (pERK1/2), but pERK1/2 nuclear translocation depended on SERT, monoamine oxidase activity, and reactive oxygen species. Nuclear translocation of pERK1/2 was required for pGATA-4-mediated transcription of S100A4/Mts1. These data provide evidence for a mechanistic link between the 5-HT pathway and S100A4/Mts1 in pulmonary hypertension and explain how the 5-HT1B receptor and SERT are codependent in regulating S100A4/Mts1.

Primary pulmonary hypertension (PPH) is a life-threatening disease. Nonparenteral prostanoids, i.e. aerosolised iloprost or oral beraprost sodium show beneficial therapeutic effects but are not sufficiently active in all patients with this devastating disease. The purpose of the present study was to determine whether the endothelin-receptor antagonist bosentan is safe and effective in patients with PPH already receiving nonparenteral prostanoids. The effect of bosentan as add-on medication was studied in 20 patients with PPH, who received either inhaled iloprost (n=9) or oral beraprost (n=11) for a median period of 16+/-13 months, by means of the 6-min walk test and cardiopulmonary exercise testing. After 3 months of administration of bosentan in addition to prostanoids, the walking distance in the 6-min walk test increased by 58+/-43 m. Cardiopulmonary exercise testing revealed an increase in maximal oxygen consumption from 11.0+/-2.3 to 13.8+/-3.6 mL x kg(-1) x min(-1) accompanied by significant improvements in anaerobic threshold, oxygen pulse and minute ventilation/carbon dioxide production slope. Peak systolic blood pressure increased from 120+/-17 to 139+/-21 mmHg. Combination treatment was well tolerated by all patients. It is concluded that the addition of the endothelin-receptor antagonist bosentan to inhaled iloprost or oral beraprost therapy appears to be safe for patients with primary pulmonary hypertension, resulting in a marked increase in exercise capacity. Therefore, rigorous studies should address whether combination treatment is more effective than either therapeutic intervention alone.

Although lung function is grossly normal in patients with primary pulmonary hypertension (PPH), mild-to-moderate peripheral airflow obstruction can be found in the majority of patients with this disease. Therefore, beta2-agonists may affect pulmonary function, blood gases and haemodynamics in patients with PPH. Pulmonary function testing, blood gas measurements and right heart catheterisation was performed in 22 patients with PPH and the acute effects of inhaled salbutamol (0.2 mg) were measured. Salbutamol caused an increase in the forced expiratory volume in one second (FEV1) from 2446+/-704 to 2550+/-776 mL. The mean expiratory flow at 50% of the vital capacity (MEF50) rose from 58+/-17 to 66+/-21% pred. The pulmonary artery pressures remained unchanged after inhalation of salbutamol, but the cardiac output increased significantly from 3.9+/-1.4 to 4.2+/-1.4 L x min(-1) accompanied by significant increases in stroke volume and mixed venous oxygen saturation as well as a significant decrease in pulmonary vascular resistance. The arterial oxygen tension rose from 9+/-2.4 kPa (68+/-18 mmHg) at baseline to 9.7+/-2.8 kPa (73+/-21 mmHg) after inhalation of salbutamol, the alveolo-arterial oxygen gradient values improved from 6+/-2.5 kPa (45+/-19 mmHg) to 5.1+/-2.9 kPa (38+/-22 mmHg), respectively. Inhaled salbutamol has beneficial acute effects on pulmonary function, blood gases and haemodynamics in patients with primary pulmonary hypertension.

Treatment with aerosolised iloprost, a prostacyclin analogue, has beneficial effects in patients with pulmonary arterial hypertension (PAH). It is unclear if patients, whose clinical condition deteriorates under treatment with aerosolised iloprost, benefit from switching to continuous intravenous iloprost. The current authors report on 16 patients with severe PAH who received continuous intravenous iloprost after primary or secondary failure of treatment with aerosolised iloprost. Determinants of efficacy were survival, New York Heart Association (NYHA) class, and walking distance in the 6-min walk test. Of 93 patients with PAH treated with aerosolised iloprost, 16 required switching to intravenous iloprost for clinical deterioration. These patients had severe right heart failure with a cardiac index of 1.6+/-0.2 L x min(-1) x m(-2) and a mixed-venous oxygen saturation of 52+/-6%. Five of these patients showed no improvement and eventually died. Three patients had further deterioration in NYHA class and exercise capacity; two of them underwent lung transplantation; the third patient is still alive. Eight patients showed marked clinical improvement; one underwent lung transplantation and the others are currently alive and stable. In the latter group of patients, the walking distance in the 6-min walk test increased from 205+/-94 to 329+/-59 m. It was not possible to identify clinical or haemodynamic factors that would predict whether switching from inhaled to intravenous iloprost would have a beneficial effect. In patients with pulmonary arterial hypertension who deteriorated while being treated with aerosolised iloprost, switching to continuous intravenous iloprost caused substantial improvement in exercise capacity in eight of 16 patients but could not prevent progression of pulmonary hypertension in the remaining eight patients. Since it was impossible to predict the individual effects of this approach, intravenous prostaglandin treatment should be considered in pulmonary arterial hypertension patients who deteriorate while receiving iloprost aerosol.

Background: Continuous intravenous infusion of prostacyclin is an effective treatment for primary pulmonary hypertension. This approach, however, requires the insertion of a permanent central venous catheter with the potential risk of serious complications. Recently, administration of aerosolized iloprost, a stable prostacyclin analogue, has been introduced as an alternative therapy for severe pulmonary hypertension., Methods: We evaluated the effects of treatment with aerosolized iloprost over a one-year period on exercise capacity and hemodynamic variables in patients with primary pulmonary hypertension., Results: Twenty-four patients with primary pulmonary hypertension received aerosolized iloprost at a cumulative daily dose of 100 to 150 micrograms for at least one year. The mean (+/- SD) walking distance in the 6-min-walk test increased from 278 +/- 96 meters at base line to 363 +/- 135 meters after 12 months (P < 0.0001). During the same period, the mean pulmonary artery pressure declined from 59 +/- 10 mmHg to 52 +/- 15 mmHg (P = 0.006), the cardiac output increased from 3.8 +/- 1.4 l/min to 4.4 +/- 1.3 l/min (P = 0.02), and the pulmonary vascular resistance declined from 1.205 +/- 467 dynes.s.cm-5 to 925 +/- 469 dynes.s.cm-5 (P = 0.0003). Treatment was generally well tolerated and except for mild coughing, minor headache and jaw pain in some patients, no side effects occurred., Conclusions: Long-term treatment with aerosolized iloprost is safe and has sustained effects on exercise capacity and pulmonary hemodynamics in patients with primary pulmonary hypertension.

Background: Continuous intravenous infusion of epoprostenol (prostacyclin) is an effective treatment for primary pulmonary hypertension. This approach requires the insertion of a permanent central venous catheter, with the associated risk of serious complications. Recently, aerosolized iloprost, a stable prostacyclin analogue, has been introduced as an alternative therapy for severe pulmonary hypertension., Methods: We evaluated the effects of aerosolized iloprost on exercise capacity and hemodynamic variables over a one-year period in patients with primary pulmonary hypertension., Results: Twenty-four patients with primary pulmonary hypertension received aerosolized iloprost at a daily dose of 100 or 150 microg for at least one year. The mean (+/-SD) distance covered in the six-minute walk test increased from 278+/-96 m at base line to 363+/-135 m after 12 months (P<0.001). During the same period, the mean pulmonary arterial pressure before the inhalation of iloprost declined from 59+/-10 mm Hg to 52+/-15 mm Hg (P=0.006), cardiac output increased from 3.8+/-1.4 liters per minute to 4.4+/-1.3 liters per minute (P=0.02), and pulmonary vascular resistance declined from 1205+/-467 dyn x sec x cm(-5) to 925+/-469 dyn x sec x cm(-5) (P<0.001). The treatment was generally well tolerated, except for mild coughing, minor headache, and jaw pain in some patients., Conclusions: Long-term treatment with aerosolized iloprost is safe and has sustained effects on exercise capacity and pulmonary hemodynamics in patients with primary pulmonary hypertension.