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Pulmonary fibrosis (PF) can be a fatal disease characterized by progressive lung scarring. It is still poorly understood how the pulmonary endothelium is involved in the disease pathogenesis. Differences of the pulmonary vasculature between patients and donors were analyzed using transmission electron microscopy, immunohistochemistry, and single-cell RNA sequencing. Vascular barrier resistance, endothelial-immune cell adhesion, and sensitivity to an inflammatory milieu were studied in vitro . Integrity and activation markers were measured by ELISA in human plasma. Transmission electron microscopy demonstrated abnormally swollen endothelial cells (ECs) in fibrotic lungs compared with donors. A more intense CD31 and von Willebrand Factor (vWF) and patchy vascular endothelial (VE)-Cadherin staining in fibrotic lungs supported the presence of a dysregulated endothelium. Integrity markers CD31, VE-Cadherin, Thrombomodulin, and VEGFR-2 (vascular endothelial growth factor receptor-2) and activation marker vWF gene expression was increased in different endothelial subpopulations (e.g., arterial, venous, general capillary, aerocytes) in PF. This was associated with a heightened sensitivity of fibrotic ECs to TNF-α or IFN-γ and elevated immune cell adhesion. The barrier strength was overall reduced in ECs from fibrotic lungs. vWF and IL-8 were increased in the plasma of patients, whereas VE-Cadherin, Thrombomodulin, and VEGFR-2 were decreased. VE-Cadherin staining was also patchy in biopsy tissue and was decreased in plasma samples of patients with PF 6 months after the initial diagnosis. Our data demonstrate highly abnormal ECs in PF. The vascular compartment is characterized by hyperactivation and increased immune cell adhesion, as well as dysfunctional endothelial barrier function. Reestablishing EC homeostasis and function might represent a new therapeutic option for fibrotic lung diseases.

The pulmonary vasculature has been frequently overlooked in acute and chronic lung diseases, such as acute respiratory distress syndrome (ARDS), pulmonary fibrosis (PF), and chronic obstructive pulmonary disease (COPD). The primary emphasis in the management of these parenchymal disorders has largely revolved around the injury and aberrant repair of epithelial cells. However, there is increasing evidence that the vascular endothelium plays an active role in the development of acute and chronic lung diseases. The endothelial cell network in the capillary bed and the arterial and venous vessels provides a metabolically highly active barrier that controls the migration of immune cells, regulates vascular tone and permeability, and participates in the remodeling processes. Phenotypically and functionally altered endothelial cells, and remodeled vessels, can be found in acute and chronic lung diseases, although to different degrees, likely because of disease-specific mechanisms. Since vascular remodeling is associated with pulmonary hypertension, which worsens patient outcomes and survival, it is crucial to understand the underlying vascular alterations. In this Review, we describe the current knowledge regarding the role of the pulmonary vasculature in the development and progression of ARDS, PF, and COPD; we also outline future research directions with the hope of facilitating the development of mechanism-based therapies.

Pulmonary arterial hypertension (PAH) is a chronic, incurable condition characterized by pulmonary vascular remodeling, perivascular inflammation, and right heart failure. Regulatory T cells (Tregs) stave off autoimmunity, and there is increasing evidence for their compromised activity in the inflammatory milieu of PAH. Abnormal Treg function is strongly correlated with a predisposition to PAH in animals and patients. Athymic Treg-depleted rats treated with SU5416, an agent causing pulmonary vascular injury, develop PAH, which is prevented by infusing missing CD4 + CD25 high FOXP3 + Tregs. Abnormal Treg activity may also explain why PAH disproportionately affects women more than men. This mini review focuses on the role of Tregs in PAH with a special view to sexual dimorphism and the future promise of Treg therapy., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Tian, Jiang, Jiang, Tamosiuniene, Kim, Guan, Arsalane, Pasupneti, Voelkel, Tang and Nicolls.)

Background: Up to 50% of chronic obstructive pulmonary disease (COPD) patients do not receive recommended care for COPD. To address this issue, we developed Proactive Integrated Care (Proactive iCare), a health care delivery model that couples integrated care with remote monitoring., Methods: We conducted a prospective, quasi-randomized clinical trial in 511 patients with advanced COPD or a recent COPD exacerbation, to test whether Proactive iCare impacts patient-centered outcomes and health care utilization. Patients were allocated to Proactive iCare (n=352) or Usual Care ( =159) and were examined for changes in quality of life using the St George's Respiratory Questionnaire (SGRQ), symptoms, guideline-based care, and health care utilization., Findings: Proactive iCare improved total SGRQ by 7-9 units ( p < 0.0001), symptom SGRQ by 9 units ( p <0.0001), activity SGRQ by 6-7 units (p <0.001) and impact SGRQ by 7-11 units ( p <0.0001) at 3, 6 and 9 months compared with Usual Care. Proactive iCare increased the 6-minute walk distance by 40 m ( p <0.001), reduced annual COPD-related urgent office visits by 76 visits per 100 participants (p <0.0001), identified unreported exacerbations, and decreased smoking ( p =0.01). Proactive iCare also improved symptoms, the b ody mass index-airway o bstruction- d yspnea- e xercise tolerance (BODE) index and oxygen titration ( p <0.05). Mortality in the Proactive iCare group (1.1%) was not significantly different than mortality in the Usual Care group (3.8%; p =0.08)., Interpretation: Linking integrated care with remote monitoring improves the lives of people with advanced COPD, findings that may have been made more relevant by the coronavirus 2019 (COVID-19) pandemic., Competing Interests: RWV, PBK, SJM, DLPD, TJF, SSJ, NFV, DJL, AB, TJS, DPR, CMK, SC, RLK and JMW received funding from the Colorado Cancer, Cardiovascular Disease and Chronic Pulmonary Disease Prevention, Early Detection and Treatment Program (CCPD). RWV and MG received funding from the National Institutes of Health. PBK worked for Robert Bosch Healthcare from 2010 to 2015 and for Philips Healthcare from 2015 to 2017, after the study was completed. RKA, FDV, JKZ and TMB had no conflicts of interest., (JCOPDF © 2021.)

Background: In animal models of pulmonary arterial hypertension (PAH), angiotensin-converting enzyme (ACE)2 and angiotensin (Ang)-(1-7) have been shown to have vasodilatory, antiproliferative, antifibrotic and antihypertrophic properties. However, the status and role of the ACE2-Ang(1-7) axis in human PAH is incompletely understood., Methods: We studied 85 patients with a diagnosis of PAH of distinct aetiologies. 55 healthy blood donors paired for age and sex served as controls. Blood samples were obtained from the pulmonary artery in patients with PAH during right heart catheterisation. Peripheral blood was obtained for both groups. Ang(1-7) and -II were measured using zone capillary electrophoresis. Aldosterone, Ang(1-9), AngA and ACE2 were measured using ELISA, and ACE2 activity was determined enzymatically., Results: Of the 85 patients, 47 had idiopathic PAH, 25 had PAH associated with congenital heart disease and 13 had PAH associated with collagen vascular disease. Compared to controls, patients with PAH had a higher concentration of AngII (median 1.03, interquartile range 0.72-1.88 pmol·mL -1 versus 0.19, 0.10-0.37 pmol·mL -1 ; p<0.001) and of aldosterone (88.7, 58.7-132 ng·dL -1 versus 12.9, 9.55-19.9 ng·dL -1 ; p<0.001). Conversely, PAH patients had a lower concentration of Ang(1-7) than controls (0.69, 0.474-0.91 pmol·mL -1 versus 4.07, 2.82-6.73 pmol·mL -1 ; p<0.001), and a lower concentration of Ang(1-9) and AngA. Similarly, the ACE2 concentration was higher than in controls (8.7, 5.35-13.2 ng·mL -1 versus 4.53, 1.47-14.3 ng·mL -1 ; p=0.011), whereas the ACE2 activity was significantly reduced (1.88, 1.08-2.81 nmol·mL -1 versus 5.97, 3.1-17.8 nmol·mL -1 ; p<0.001). No significant differences were found among the three different aetiological forms of PAH., Conclusions: The AngII-ACE2-Ang(1-7) axis appears to be altered in human PAH and we propose that this imbalance, in favour of AngII, plays a role in the pathogenesis of the severe PAH. Further mechanistic studies are warranted., Competing Interests: Conflict of interest: J. Sandoval has nothing to disclose. Conflict of interest: L. Del Valle-Mondragón has nothing to disclose. Conflict of interest: F. Masso has nothing to disclose. Conflict of interest: N. Zayas has nothing to disclose. Conflict of interest: T. Pulido reports grants from and personal fees for advisory board work and lectures from Actelion and Bayer, grants from Lilly, Reata Pharmaceuticals and United Therapeutics, personal fees for advisory board work from Pfizer and Akros Pharma, outside the submitted work. Conflict of interest: R. Teijeiro reports grants from CONACYT (FOSISS project 2015-1-262511), during the conduct of the study. Conflict of interest: H. González-Pacheco has nothing to disclose. Conflict of interest: R. Olmedo-Ocampo has nothing to disclose. Conflict of interest: C. Sisniega has nothing to disclose. Conflict of interest: A. Paez-Arenas has nothing to disclose. Conflict of interest: G. Pastelin-Hernandez has nothing to disclose. Conflict of interest: J. Gómez-Arroyo has nothing to disclose. Conflict of interest: N.F. Voelkel has nothing to disclose., (Copyright ©ERS 2020.)

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.

It has been generally accepted that severe forms of pulmonary arterial hypertension are associated with inflammation. Plasma levels in patients with severe pulmonary arterial hypertension show elevated levels of interleukins and mediators of inflammation and histologically the diseased small pulmonary arterioles show infiltrates of inflammatory and immune cells. Here, we review the literature that connects pulmonary hypertension with the arachidonic acid/5-lipoxygenase-derived leukotriens. This mostly preclinical background data together with the availability of 5-lipoxygenase inhibitors and leukotriene receptor blockers provide the rationale for testing the hypothesis that 5-lipoxygenase products contribute to the pathobiology of severe pulmonary arterial hypertension in a subgroup of patients., (© The Author(s) 2020.)

Pulmonary arterial hypertension is a fatal disease associated with pulmonary vascular remodeling and right ventricular hypertrophy. Pre-clinical animal models that reproduce the human pulmonary arterial hypertension process and pharmacological response to available therapies are critical for future drug development. The most prevalent animal model reproducing many aspects of angioobliterative forms of pulmonary arterial hypertension is the rat Sugen/hypoxia model in which Sugen, a vascular endothelial growth factor receptor antagonist, primarily causes initiation of endothelial injury and later in the presence of hypoxia promotes proliferation of apoptosis-resistant endothelial cells. We previously demonstrated that exposure of human pulmonary microvascular endothelium to morphine and HIV-proteins results in initial apoptosis followed by increased proliferation. Here, we demonstrate that the double-hit of morphine and Sugen 5416 (Sugen-morphine) in rats leads to the development of pulmonary arterial hypertension with significant medial hypertrophy of pre-acinar pulmonary arteries along with neo-intimal thickening of intra-acinar vessels. In addition, the pulmonary smooth muscle and endothelial cells isolated from Sugen-morphine rats showed hyperproliferation and apoptotic resistance, respectively, in response to serum starvation. Our findings support that the dual hit model of Sugen 5416 and morphine provides another experimental strategy to induce significant pulmonary vascular remodeling and development of severe pulmonary arterial hypertension pathology in rats without exposure to hypoxia., (© The Author(s) 2020.)

Background: Bmpr2 (bone morphogenetic protein receptor 2) mutations are critical risk factors for hereditary pulmonary arterial hypertension (PAH) with approximately 20% of carriers developing disease. There is an unmet medical need to understand how environmental factors, such as inflammation, render Bmpr2 mutants susceptible to PAH. Overexpressing 5-LO (5-lipoxygenase) provokes lung inflammation and transient PAH in Bmpr2 +/ - mice. Accordingly, 5-LO and its metabolite, leukotriene B 4 , are candidates for the second hit. The purpose of this study was to determine how 5-LO-mediated pulmonary inflammation synergized with phenotypically silent Bmpr2 defects to elicit significant pulmonary vascular disease in rats., Methods: Monoallelic Bmpr2 mutant rats were generated and found phenotypically normal for up to 1 year of observation. To evaluate whether a second hit would elicit disease, animals were exposed to 5-LO-expressing adenovirus, monocrotaline, SU5416, SU5416 with chronic hypoxia, or chronic hypoxia alone. Bmpr2 -mutant hereditary PAH patient samples were assessed for neointimal 5-LO expression. Pulmonary artery endothelial cells with impaired BMPR2 signaling were exposed to increased 5-LO-mediated inflammation and were assessed for phenotypic and transcriptomic changes., Results: Lung inflammation, induced by intratracheal delivery of 5-LO-expressing adenovirus, elicited severe PAH with intimal remodeling in Bmpr2 +/- rats but not in their wild-type littermates. Neointimal lesions in the diseased Bmpr2 +/- rats gained endogenous 5-LO expression associated with elevated leukotriene B 4 biosynthesis. Bmpr2 -mutant hereditary PAH patients similarly expressed 5-LO in the neointimal cells. In vitro, BMPR2 deficiency, compounded by 5-LO-mediated inflammation, generated apoptosis-resistant and proliferative pulmonary artery endothelial cells with mesenchymal characteristics. These transformed cells expressed nuclear envelope-localized 5-LO consistent with induced leukotriene B 4 production, as well as a transcriptomic signature similar to clinical disease, including upregulated nuclear factor Kappa B subunit (NF-κB), interleukin-6, and transforming growth factor beta (TGF-β) signaling pathways. The reversal of PAH and vasculopathy in Bmpr2 mutants by TGF-β antagonism suggests that TGF-β is critical for neointimal transformation., Conclusions: In a new 2-hit model of disease, lung inflammation induced severe PAH pathology in Bmpr2 +/- rats. Endothelial transformation required the activation of canonical and noncanonical TGF-β signaling pathways and was characterized by 5-LO nuclear envelope translocation with enhanced leukotriene B 4 production. This study offers an explanation of how an environmental injury unleashes the destructive potential of an otherwise silent genetic mutation.

Rationale: CYPs (cytochrome p450) are critically involved in the metabolism of xenobiotics and toxins. Given that pulmonary hypertension is strongly associated with environmental exposure, we hypothesize that CYPs play a role in the development and maintenance of pathological vascular remodeling., Objective: We sought to identify key CYPs that could link drug or hormone metabolism to the development of pulmonary hypertension., Methods and Results: We searched in Medline (PubMed) database, as well as http://www.clinicaltrials.gov, for CYPs associated with many key aspects of pulmonary arterial hypertension including, but not limited to, severe pulmonary hypertension, estrogen metabolism, inflammation mechanisms, quasi-malignant cell growth, drug susceptibility, and metabolism of the pulmonary arterial hypertension-specific drugs., Conclusions: We postulate a hypothesis where the AhR (aryl hydrocarbon receptor) mediates aberrant cell growth via expression of different CYPs associated with estrogen metabolism and inflammation.

Heart failure (HF) is usually defined by the dominantly affected heart chamber; therefore, termed right or left HF (RHF or LHF). Pulmonologists understand RHF as a complex syndrome characterized by insufficient delivery of blood from the right ventricle associated with elevated systemic venous pressure at rest or exercise. Cardiologists specify LHF by its clinical functional class and the relation to a reduced (HFrEF), preserved (HFpEF) or mid-range ejection fraction (HFmrEF). Pediatric cardiologist, dealing also with patients with a failing single ventricle, define HF as a condition of insufficient systemic oxygen delivery (DO 2 ). Certainly, pediatricians do not think of the right and left heart, or even a single ventricle as an isolated, independently acting entity. Because of the importance of cardiac interactions, the creation of a restrictive atrial communication aims at a palliative approach with the goal to diminish the congestive consequences of a dysfunctional ventricle; further to serve as a pop-off valve in order to prevent syncope and cardiovascular collapse. This review covers the background, the particular indications, the techniques and preliminary results achieved following the creation of a restrictive atrial septum defect (rASD) in different pathophysiological settings. Based on the institutional experience, percutaneous trans-catheter perforation of the atrial septum, followed by gradual balloon dilatation can be performed at any age and location worldwide. Medical institutions in low resource countries can make use of such palliating procedures in the setting of right as well as LHF independent of their pharmacological facilities., Competing Interests: Conflicts of Interest: The authors have no conflicts of interest to declare.

Background: Impaired angiogenesis is assumed to be an important factor in the development of chronic thromboembolic pulmonary hypertension (CTEPH). However, the role of endothelial cells (ECs) in CTEPH remains unclear. The aim of this study was to investigate the angiogenic potential of ECs from pulmonary endarterectomy (PEA) specimens., Methods: We isolated ECs from PEA specimens (CTEPH-ECs) and control EC lines from the intact pulmonary arteries of patients with peripheral lung cancers, using a MACS system. These cells were analyzed in vitro including PCR-array analysis, and the PEA specimens were analyzed with immunohistochemistry. Additionally, the serum HGF levels were determined in CTEPH patients., Results: A three-dimensional culture assay revealed that CTEPH-ECs were highly angiogenic. An angiogenesis-focused gene PCR array revealed a high expression of hepatocyte growth factor (HGF) in CTEPH-ECs. The high expression of HGF was also confirmed in the supernatant extracted from PEA specimens. The immunohistochemical analysis showed expression of HGF on the surface of the thrombus vessels. The serum HGF levels in CTEPH patients were higher than those in pulmonary thromboembolism survivors., Conclusion: Our study suggests that there are ECs with pro-angiogenetic character and high expression of HGF in PEA specimens. It remains unknown how these results are attributable to the etiology. However, further investigation focused on the HGF pathway may provide novel diagnostic and therapeutic tools for patients with CTEPH.

Background: Left atrial decompression is considered in patients with symptomatic heart failure with preserved ejection fraction (HFpEF). We aimed to evaluate the feasibility and efficacy of transcatheter generation of a restrictive atrial septum communication to manage HFpEF from infancy to adulthood with cardiomyopathy and congenital heart defect., Methods and Results: From June 2009 to December 2016, 24 patients (50% with an age less than 16 years) with HFpEF were palliated; NYHA-/Ross class IV (n = 10); median systemic ventricular ejection fraction 64 (range 35-78) %. Cardiomyopathy was classified as a restrictive (n = 4) or hypertrophic (n = 2). (75% related to congenital heart defects) Three patients had a systemic right ventricle; in the majority of patients, HFpEF was associated to complex congenital heart defects (n = 18). Mean pulmonary arterial pressures (PAP systolic/diastolic) were 56/28 (± 24/13), left atrial pressures (LAP, v-, a-wave, mean) 26/25/20 (± 7/10/6). Trans-septal puncture was used in 22 patients; foramen ovale dilatation in 2 patients. Median balloon size was 12 (range 6-18) mm; procedure time including diagnostic measures 125 (83-221) min. No procedural death or complications were observed. Mean LA-pressures decreased significantly to 19/19/15 ± 6/8/5 mmHg (p = 0.05); median brain natriuretic peptide (BNP) decreased from 392 (range 93-4401) pg/ml median BNP to 314 (range 61-1544) pg/ml (p = 0.05). Three patients died; one patient received orthotopic heart and one patient a heart-lung transplantation. No patient required so far an assist device. Clinical improvement occurred in all patients, in some after additional surgical or interventional approach., Conclusions: Transcatheter LA decompression is an age-independent, effective palliation treating patients with HFpEF.

Background: Right ventricular (RV) adaptation to acute and chronic pulmonary hypertensive syndromes is a significant determinant of short- and long-term outcomes. Although remarkable progress has been made in the understanding of RV function and failure since the meeting of the NIH Working Group on Cellular and Molecular Mechanisms of Right Heart Failure in 2005, significant gaps remain at many levels in the understanding of cellular and molecular mechanisms of RV responses to pressure and volume overload, in the validation of diagnostic modalities, and in the development of evidence-based therapies., Methods: A multidisciplinary working group of 20 international experts from the American Thoracic Society Assemblies on Pulmonary Circulation and Critical Care, as well as external content experts, reviewed the literature, identified important knowledge gaps, and provided recommendations., Results: This document reviews the knowledge in the field of RV failure, identifies and prioritizes the most pertinent research gaps, and provides a prioritized pathway for addressing these preclinical and clinical questions. The group identified knowledge gaps and research opportunities in three major topic areas: 1) optimizing the methodology to assess RV function in acute and chronic conditions in preclinical models, human studies, and clinical trials; 2) analyzing advanced RV hemodynamic parameters at rest and in response to exercise; and 3) deciphering the underlying molecular and pathogenic mechanisms of RV function and failure in diverse pulmonary hypertension syndromes., Conclusions: This statement provides a roadmap to further advance the state of knowledge, with the ultimate goal of developing RV-targeted therapies for patients with RV failure of any etiology.

Rationale: Pulmonary arterial hypertension (PH) is a life-threatening condition associated with immune dysregulation and abnormal regulatory T cell (Treg) activity, but it is currently unknown whether and how abnormal Treg function differentially affects males and females., Objective: To evaluate whether and how Treg deficiency differentially affects male and female rats in experimental PH., Methods and Results: Male and female athymic rnu/rnu rats, lacking Tregs, were treated with the VEGFR2 (vascular endothelial growth factor receptor 2) inhibitor SU5416 or chronic hypoxia and evaluated for PH; some animals underwent Treg immune reconstitution before SU5416 administration. Plasma PGI 2 (prostacyclin) levels were measured. Lung and right ventricles were assessed for the expression of the vasoprotective proteins COX-2 (cyclooxygenase 2), PTGIS (prostacyclin synthase), PDL-1 (programmed death ligand 1), and HO-1 (heme oxygenase 1). Inhibitors of these pathways were administered to athymic rats undergoing Treg immune reconstitution. Finally, human cardiac microvascular endothelial cells cocultured with Tregs were evaluated for COX-2, PDL-1, HO-1, and ER (estrogen receptor) expression, and culture supernatants were assayed for PGI 2 and IL (interleukin)-10. SU5416-treatment and chronic hypoxia produced more severe PH in female than male athymic rats. Females were distinguished by greater pulmonary inflammation, augmented right ventricular fibrosis, lower plasma PGI 2 levels, decreased lung COX-2, PTGIS, HO-1, and PDL-1 expression and reduced right ventricular PDL-1 levels. In both sexes, Treg immune reconstitution protected against PH development and raised levels of plasma PGI 2 and cardiopulmonary COX-2, PTGIS, PDL-1, and HO-1. Inhibiting COX-2, HO-1, and PD-1 (programmed death 1)/PDL-1 pathways abrogated Treg protection. In vitro, human Tregs directly upregulated endothelial COX-2, PDL-1, HO-1, ERs and increased supernatant levels of PGI 2 and IL-10., Conclusions: In 2 animal models of PH based on Treg deficiency, females developed more severe PH than males. The data suggest that females are especially reliant on the normal Treg function to counteract the effects of pulmonary vascular injury leading to PH., (© 2018 American Heart Association, Inc.)

Drug-induced pulmonary arterial hypertension (D-PAH) is a form of World Health Organization Group 1 pulmonary hypertension (PH) defined by severe small vessel loss and obstructive vasculopathy, which leads to progressive right heart failure and death. To date, 16 different compounds have been associated with D-PAH, including anorexigens, recreational stimulants, and more recently, several Food and Drug Administration-approved medications. Although the clinical manifestation, pathology, and hemodynamic profile of D-PAH are indistinguishable from other forms of pulmonary arterial hypertension, its clinical course can be unpredictable and to some degree dependent on removal of the offending agent. Because only a subset of individuals develop D-PAH, it is probable that genetic susceptibilities play a role in the pathogenesis, but the characterization of the genetic factors responsible for these susceptibilities remains rudimentary. Besides aggressive treatment with PH-specific therapies, the major challenge in the management of D-PAH remains the early identification of compounds capable of injuring the pulmonary circulation in susceptible individuals. The implementation of pharmacovigilance, precision medicine strategies, and global warning systems will help facilitate the identification of high-risk drugs and incentivize regulatory strategies to prevent further outbreaks of D-PAH. The goal for this review is to inform clinicians and scientists of the prevalence of D-PAH and to highlight the growing number of common drugs that have been associated with the disease.

Atrial septostomy (AS) is recommended for pulmonary arterial hypertension (PAH)-associated right ventricular (RV) failure, recurrent syncope, or pulmonary hypertensive crisis (PHC). We aimed to evaluate the feasibility and efficacy of AS to manage PAH from infancy to adulthood. From June 2009 to December 2016, transcatheter atrial communications were created in 11 PAH patients (4 girls/women; median age = 4.3 years; range = 33 days-26 years; median body weight = 14 kg; range = 3-71 kg; NYHA-/Ross class IV; n = 11). PAH was classified as idiopathic (n = 6) or secondary (n = 5). History of syncope was dominant (n = 6); two with patent foramen ovale (PFO) admitted with recurrent PHC, three patients required resuscitation before AS. Three patients had PAH-associated low cardiac output. The average pulmonary arterial pressures (PAP systolic/diastolic) were 101/50 (±34/23); the corresponding systemic arterial pressures (SAP) were 99/54 (±23/11); and the mean ratio of PAPd / SAPd was 0.97 (±0.4). Percutaneous trans-septal puncture was uneventfully performed in nine patients; a PFO was dilated in two patients. There was no procedure-related mortality. The median balloon size was 10 mm (range = 6-14 mm); the mean catheter time was 174.6 ± 48 min; fluoroscopy time was 19.8 (±11) min. Syncope and PHC were successfully treated in all patients. The mean arterial oxygen saturation decreased from 97 ± 2 to 89 ± 11.7. One patient died awaiting lung transplantation, one continues to be listed; two patients received a reverse Potts-shunt, one patient died during follow-up; seven patients are stable with PAH-specific treatment. Percutaneous AS is an effective method palliating PAH-associated syncope, PHCs or right (bi-) ventricular heart failure.

Fatal pulmonary arterial hypertension (PAH) affects HIV-infected individuals at significantly higher frequencies. We previously showed plexiform-like lesions characterized by recanalized lumenal obliteration, intimal disruption, medial hypertrophy, and thrombosis consistent with PAH in rhesus macaques infected with chimeric SHIVnef but not with the parental SIVmac239, suggesting that Nef is implicated in the pathophysiology of HIV-PAH. However, the current literature on non-human primates as animal models for SIV(HIV)-associated pulmonary disease reports the ultimate pathogenic pulmonary outcomes of the research efforts; however, the variability and features in the actual disease progression remain poorly described, particularly when using different viral sources for infection. We analyzed lung histopathology, performed immunophenotyping of cells in plexogenic lesions pathognomonic of PAH, and measured cardiac hypertrophy biomarkers and cytokine expression in plasma and lung of juvenile SHIVnef-infected macaques. Here, we report significant hematopathologies, changes in cardiac biomarkers consistent with ventricular hypertrophy, significantly increased levels of interleukin-12 and GM-CSF and significantly decreased sCD40 L, CCL-2, and CXCL-1 in plasma of the SHIVnef group. Pathway analysis of inflammatory gene expression predicted activation of NF-κB transcription factor RelB and inhibition of bone morphogenetic protein type-2 in the setting of SHIVnef infection. Our findings highlight the utility of SHIVnef-infected macaques as suitable models of HIV-associated pulmonary vascular remodeling as pathogenetic changes are concordant with features of idiopathic, familial, scleroderma, and HIV-PAH.

Background: The p53 signaling pathway may be important for the pathogenesis of emphysematous changes in the lungs of smokers. Polymorphism of p53 at codon 72 is known to affect apoptotic effector proteins, and the polymorphism of mouse double minute 2 homolog (MDM2) single nucleotide polymorphism (SNP)309 is known to increase MDM2 expression. The aim of this study was to assess polymorphisms of the p53 and MDM2 genes in smokers and confirm the role of SNPs in these genes in the pathogenesis of pulmonary emphysema., Methods: This study included 365 patients with a smoking history, and the polymorphisms of p53 and MDM2 genes were identified. The degree of pulmonary emphysema was determined by means of CT scanning. SNPs, MDM2 mRNA, and p53 protein levels were assessed in human lung tissues from smokers. Plasmids encoding p53 and MDM2 SNPs were used to transfect human lung fibroblasts (HLFs) with or without cigarette smoke extract (CSE), and the effects on cell proliferation and MDM2 promoter activity were measured., Results: The polymorphisms of the p53 and MDM2 genes were associated with emphysematous changes in the lung and were also associated with p53 protein and MDM2 mRNA expression in the lung tissue samples. Transfection with a p53 gene-coding plasmid regulated HLF proliferation, and the analysis of P2 promoter activity in MDM2 SNP309-coding HLFs showed the promoter activity was altered by CSE., Conclusions: Our data demonstrated that p53 and MDM2 gene polymorphisms are associated with apoptotic signaling and smoking-related emphysematous changes in lungs from smokers., (Copyright © 2017 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.)

Acquired lymphedema is a cancer sequela and a global health problem currently lacking pharmacologic therapy. We have previously demonstrated that ketoprofen, an anti-inflammatory agent with dual 5-lipoxygenase and cyclooxygenase inhibitory properties, effectively reverses histopathology in experimental lymphedema. We show that the therapeutic benefit of ketoprofen is specifically attributable to its inhibition of the 5-lipoxygenase metabolite leukotriene B 4 (LTB 4 ). LTB 4 antagonism reversed edema, improved lymphatic function, and restored lymphatic architecture in the murine tail model of lymphedema. In vitro, LTB 4 was functionally bimodal: Lower LTB 4 concentrations promoted human lymphatic endothelial cell sprouting and growth, but higher concentrations inhibited lymphangiogenesis and induced apoptosis. During lymphedema progression, lymphatic fluid LTB 4 concentrations rose from initial prolymphangiogenic concentrations into an antilymphangiogenic range. LTB 4 biosynthesis was similarly elevated in lymphedema patients. Low concentrations of LTB 4 stimulated, whereas high concentrations of LTB 4 inhibited, vascular endothelial growth factor receptor 3 and Notch pathways in cultured human lymphatic endothelial cells. Lymphatic-specific Notch1 -/- mice were refractory to the beneficial effects of LTB 4 antagonism, suggesting that LTB 4 suppression of Notch signaling is an important mechanism in disease maintenance. In summary, we found that LTB 4 was harmful to lymphatic repair at the concentrations observed in established disease. Our findings suggest that LTB 4 is a promising drug target for the treatment of acquired lymphedema., (Copyright © 2017, American Association for the Advancement of Science.)

The final therapy of 'end-stage heart failure' is orthotopic heart, lung or heart-lung transplantation. However, these options are not available for many patients worldwide. Therefore, novel therapeutical strategies are needed. Based on pathophysiological insights regarding (1) the long-term impact of an obstructive pulmonary outflow tract in neonates with congenitally corrected transposition of the great arteries, (2) the importance of a restrictive versus a non-restrictive atrial septum in neonates born with a borderline left ventricle and (3) the significance of both, a patent foramen ovale and/or open ductus arteriosus for survival of newborns with persistent pulmonary hypertension, the current review introduces some therapeutical strategies that may be applicable to selected patients with heart failure. These strategies include (1) reversible pulmonary artery banding in left ventricular-dilated cardiomyopathy with preserved right ventricular function, (2) the creation of restrictive interatrial communication to treat diastolic (systolic) heart failure, (3) atrioseptostomy or reverse Potts shunt in pulmonary arterial hypertension and (4) return to a fetal, parallel circulation by combining atrioseptostomy and reversed Potts shunt with or without placement of a bilateral pulmonary artery banding. While still being experimental, it is hoped that the procedures presented in the current overview will inspire future novel therapeutic strategies that may be applicable to selected patients with heart failure., Competing Interests: Competing interests: None., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)

Background: Cigarette smoke induced oxidative stress has been shown to reduce silent information regulator 1 (Sirt1) levels in lung tissue from smokers and patients with COPD patients. Sirt1 is known to inhibit endothelial senescence and may play a protective role in vascular cells. Endothelial progenitor cells (EPCs) are mobilized into circulation under various pathophysiological conditions, and are thought to play an important role in tissue repair in chronic obstructive lung disease (COPD). Therefore, Sirt1 and EPC-associated mRNAs were measured in blood samples from patients with COPD and from cultured CD34 + progenitor cells to examine whether these genes are associated with COPD development., Methods: This study included 358 patients with a smoking history of more than 10 pack-years. RNA was extracted from blood samples and from CD34 + progenitor cells treated with cigarette smoke extract (CSE), followed by assessment of CD31, CD34, Sirt1 mRNA, miR-34a, and miR-126-3p expression by real-time RT-PCR., Results: The expression of CD31, CD34, Sirt1 mRNAs, and miR-126-3p decreased and that of miR-34a increased in moderate COPD compared with that in control smokers. However, no significant differences in these genes were observed in blood cells from patients with severe COPD compared with those in control smokers. CSE significantly decreased Sirt1 and increased miR-34a expression in cultured progenitor cells., Conclusion: Sirt1 expression in blood cells from patients with COPD could be a biomarker for disease stability in patients with moderate COPD. MiR-34a may participate in apoptosis and/or senescence of EPCs in smokers. Decreased expression of CD31, CD34, and miR-126-3p potentially represents decreased numbers of EPCs in blood cell from patients with COPD.

Background/objectives: Several studies have already shown the correlation between the right ventricle (RV) hemodynamic values and either glucose uptake or fatty acid uptake in the RV, respectively. However, there are few studies to compare the RV metabolic alteration before and after treatment for pulmonary hypertension. The aims of this study are to assess right ventricular glucose and fatty acid in chronic thromboembolic pulmonary hypertension (CTEPH) patients before and after pulmonary thromboendarterectomy and to examine whether there is a correlation between right ventricular glucose and fatty acid uptake., Methods: To assess glucose and fatty acid accumulation in the RV, [(18)F] fluoro-2-deoxyglucose (FDG)-positron emission tomography (PET) and (123)I-β-methyl iodophenyl pentadecanoic acid (BMIPP) imaging were performed in CTEPH patients before (FDG: n=20, BMIPP: n=13) and after (FDG: n=12, BMIPP: n=8) thromboendarterectomy., Results: Both [(18)F] FDG uptake and (123)I-BMIPP uptake in RV of post-PEA patients obviously decreased after this operation procedure (p<0.01). The right ventricle [(18)F] FDG uptake was also significantly correlated with (123)I-BMIPP uptake (r=0.45, p=0.04)., Conclusions: In this study, we observed that both glucose and fatty acid accumulated in the RV of patients with CTEPH. Although the exact details of the altered energy metabolism in the stressed RV remain unknown, this is the first study to evaluate both glucose and fatty acid uptake before and after thromboendarterectomy in patients with CTEPH, even though the number of the patient is limited., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Here, we tested the hypothesis that animals with severe pulmonary arterial hypertension (PAH) display increased sensitivity to vascular permeability induced by activation of store-operated calcium entry. To test this hypothesis, wild-type and transient receptor potential channel 4 (TRPC4) knockout Fischer 344 rats were given a single injection of Semaxanib (SU5416; 20 mg/kg) followed by 3 wk of exposure to hypoxia (10% oxygen) and a return to normoxia (21% oxygen) for an additional 2-3 wk. This Semaxanib/hypoxia/normoxia (i.e., SU5416/hypoxia/normoxia) treatment caused PAH, as evidenced by development of right ventricular hypertrophy, pulmonary artery medial hypertrophy, and occlusive lesions within precapillary arterioles. Pulmonary artery pressure was increased fivefold in Semaxanib/hypoxia/normoxia-treated animals compared with untreated, Semaxanib-treated, and hypoxia-treated controls, determined by isolated perfused lung studies. Thapsigargin induced a dose-dependent increase in permeability that was dependent on TRPC4 in the normotensive perfused lung. This increase in permeability was accentuated in PAH lungs but not in Semaxanib- or hypoxia-treated lungs. Fluid accumulated in large perivascular cuffs, and although alveolar fluid accumulation was not seen in histological sections, Evans blue dye conjugated to albumin was present in bronchoalveolar lavage fluid of hypertensive but not normotensive lungs. Thus PAH is accompanied by a TRPC4-dependent increase in the sensitivity to edemagenic agents that activate store-operated calcium entry., (Copyright © 2016 the American Physiological Society.)

Introduction: Inflammatory cells are present in the lungs from patients with many, if not all, forms of severe pulmonary hypertension., Areas Covered: Historically the first inflammatory cell identified in the pulmonary vascular lesions was the mast cell. T and B lymphocytes, as well as macrophages, are present in and around the pulmonary arterioles and many patients have elevated blood levels of interleukin 1 and 6; some patients show elevated levels of leukotriene B4. An overlap between collagen-vascular disease-associated pulmonary arterial hypertension (PAH) and idiopathic PAH exists, yet only a few studies have been designed that evaluate the effect of anti-inflammatory treatments. Here we review the pertinent data that connect PAH and inflammation/autoimmune dysregulation and evaluate experimental models of severe PAH with an emphasis on the Sugen/athymic rat model of severe PAH. Expert commentary: We postulate that there are several inflammatory phenotypes and predict that there will be several anti-inflammatory treatment strategies for severe PAH., Competing Interests: Declaration of interest This paper was funded by grants from the National Instituted of Health (grant numbers 5PO1HL014985, R01HLI22887). M Nicolls is the cofounder of Eiccose LLC, a company investigating targeting LTB4 in pulmonary hypertension. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

In patients with pulmonary hypertension (PH), the primary cause of death is right ventricular (RV) failure. Improvement in RV function is therefore one of the most important treatment goals. In order to be able to reverse RV dysfunction and also prevent RV failure, a detailed understanding of the pathobiology of RV failure and the underlying mechanisms concerning the transition from a pressure-overloaded adapted right ventricle to a dilated and failing right ventricle is required. Here, we propose that insufficient RV contractility, myocardial fibrosis, capillary rarefaction, and a disturbed metabolism are important features of a failing right ventricle. Furthermore, an overview is provided about the potential direct RV effects of PH-targeted therapies and the effects of RV-directed medical treatments.

Unlabelled: Major advances in chronic heart failure (cHF) therapy have been achieved and documented in adult patients, while research regarding the mechanisms and therapy of cHF in children has lagged behind. Based on receptor physiological studies and pharmacological knowledge, treatment with specific ß1-adrenergic receptor blocker (ARB), tissue angiotensin-converting enzyme inhibitor (ACE-I), and mineralocorticoid antagonists have to be recommended in children despite lack of sufficient data derived from prospective randomized studies. At our institution, bisoprolol, lisinopril, and spironolactone have been firmly established to treat systolic cHF, hypoplastic left heart syndrome (HLHS) following hybrid approach and congenital left-right shunt diseases, latest in patients where surgery has to be delayed. Chronic therapy with long-acting diuretics and fluid restriction are not advocated because short-term effects are achieved at the expense of further neuro-humoral stimulation. It remains unclear why diuretics are recommended although evidence-based studies, documenting long-term benefit, are missing. However, that is true for all currently used drugs for pediatric cHF., Conclusion: This review focuses on the prevailing "nihilism" of cHF therapy in children with the goal to encourage physicians to treat pediatric cHF with a rationally designed therapy, which combines available agents that have been shown to improve survival in adult patients with cHF. Because of the lack of clinical trials, which generate the needed evidence, surrogate variables like heart and respiratory rate, weight gain, image-derived data, and biomarkers should be monitored and used instead. The recommended pharmacological therapy for systolic heart failure is also provided as the basis for utilizing reversible pulmonary arterial banding (PAB) as a novel strategy in young children with dilative cardiomyopathy (DCM) with preserved right ventricular function., What Is Known: • Heart failure (HF) in children is a serious public health concern. • HF has numerous etiologies, but unspecific symptoms. • HF interplays among neuro-humoral, and molecular abnormalities. • Pediatric cHF-therapy is currently based on loop-diuretics, fluid restriction and digoxin. What is New: • Cardiac function analysis has to include cardiac synchrony and VVI. • Considering enormous potential of cardiac regeneration, therapy has to extend with selective ß1-ARB, tissue ACE-I and mineralocorticoid blockers, loop-diuretics avoided as ever possible. • Inhibition of the endogenous neuro-humoral stimulation is monitored by surrogate parameters as heart and breath rate and systolic and diastolic blood pressure. • Advocated HF therapy serves for regenerative strategies as reversible Pulmonary Artery Banding in DCM.

A recent study demonstrated a significant role for leukotriene B4 (LTB4) causing pulmonary vascular remodeling in pulmonary arterial hypertension. LTB4 was found to directly injure luminal endothelial cells and promote growth of the smooth muscle cell layer of pulmonary arterioles. The purpose of this study was to determine the effects of LTB4 on the pulmonary adventitial layer, largely composed of fibroblasts. Here, we demonstrate that LTB4 enhanced human pulmonary artery adventitial fibroblast proliferation, migration, and differentiation in a dose-dependent manner through its cognate G-protein-coupled receptor, BLT1. LTB4 activated human pulmonary artery adventitial fibroblast by upregulating p38 mitogen-activated protein kinase as well as Nox4-signaling pathways. In an autoimmune model of pulmonary hypertension, inhibition of these pathways blocked perivascular inflammation, decreased Nox4 expression, reduced reactive oxygen species production, reversed arteriolar adventitial fibroblast activation, and attenuated pulmonary hypertension development. This study uncovers a novel mechanism by which LTB4 further promotes pulmonary arterial hypertension pathogenesis, beyond its established effects on endothelial and smooth muscle cells, by activating adventitial fibroblasts., (© 2015 American Heart Association, Inc.)

Increased serotonin serum levels have been proposed to play a key role in pulmonary arterial hypertension (PAH) by regulating vessel tone and vascular smooth muscle cell proliferation. An intact serotonin system, which critically depends on a normal function of the serotonin transporter (SERT), is required for the development of experimental pulmonary hypertension in rodents exposed to hypoxia or monocrotaline. While these animal models resemble human PAH only with respect to vascular media remodeling, we hypothesized that SERT is likewise required for the presence of lumen-obliterating intima remodeling, a hallmark of human PAH reproduced in the Sugen hypoxia (SuHx) rat model of severe angioproliferative pulmonary hypertension. Therefore, SERT wild-type (WT) and knockout (KO) rats were exposed to the SuHx protocol. SERT KO rats, while completely lacking SERT, were hemodynamically indistinguishable from WT rats. After exposure to SuHx, similar degrees of severe angioproliferative pulmonary hypertension and right ventricular hypertrophy developed in WT and KO rats (right ventricular systolic pressure 60 vs. 55 mmHg, intima thickness 38 vs. 30%, respectively). In conclusion, despite its implicated importance in PAH, SERT does not play an essential role in the pathogenesis of severe angioobliterative pulmonary hypertension in rats exposed to SuHx., (Copyright © 2015 the American Physiological Society.)

Rationale: In right ventricular hypertrophy associated with severe pulmonary hypertension (PH), a shift of energy metabolism toward glycolysis occurs. There are few investigations regarding fatty acid metabolism in patients with PH and right ventricular hypertrophy., Objectives: To assess whether there is fatty acid accumulation in the hypertrophied right ventricle in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and to determine whether this accumulation is related to hemodynamic variables obtained by right heart catheterization., Methods: To assess fatty acid accumulation in the right ventricle, 123I-β-methyl iodophenyl pentadecanoic acid (BMIPP) analog imaging was performed in control subjects (n=16) and patients with CTEPH (n=13) before (n=13) and after (n=8) pulmonary thromboendarterectomy., Measurements and Main Results: There was increased 123I-BMIPP uptake in the right ventricle of subjects with CTEPH before pulmonary endarterectomy. Right ventricular 123I-BMIPP uptake decreased significantly after thromboendarterectomy (P=0.003) in parallel with the change of hemodynamic variables. The right ventricular BMIPP uptake was significantly correlated with the mean pulmonary artery pressure (r=0.51, P=0.0228) but not with pulmonary vascular resistance (r=0.39, P=0.0932)., Conclusions: This is the first study that uses 123I-BMIPP uptake imaging to show that fatty acid accumulates in the right ventricle of patients with CTEPH and that the increased accumulation is reversible after pulmonary thromboendarterectomy. This study suggests that this imaging modality may be useful for monitoring right ventricle metabolic functions in severe PH.

Given the difficulty of diagnosing early-stage pulmonary arterial hypertension (PAH) due to the lack of signs and symptoms, and the risk of an open lung biopsy, the precise pathological features of presymptomatic stage lung tissue remain unknown. It has been suggested that the maximum elevation of the mean pulmonary arterial pressure (P pa) is achieved during the early symptomatic stage, indicating that the elevation of the mean P pa is primarily driven by the pulmonary vascular tone and/or some degree of pulmonary vascular remodeling completed during this stage. Recently, the examination of a rat model of severe PAH suggested that the severe PAH may be primarily determined by the presence of intimal lesions and/or the vascular tone in the early stage. Human data seem to indicate that intimal lesions are essential for the severely increased pulmonary arterial blood pressure in the late stage of the disease.However, many questions remain. For instance, how does the pulmonary hemodynamics change during the course of the disease, and what drives the development of severe PAH? Although it is generally acknowledged that both pulmonary vascular remodeling and the vascular tone are important determinants of an elevated pulmonary arterial pressure, which is the root cause of the time-dependent progression of the disease? Here we review the recent histopathological concepts of PAH with respect to the progression of the lung vascular disease.

Inflammation and altered immunity are recognized components of severe pulmonary arterial hypertension in human patients and in animal models of PAH. While eicosanoid metabolites of cyclooxygenase and lipoxygenase pathways have been identified in the lungs from pulmonary hypertensive animals their role in the pathogenesis of severe angioobliterative PAH has not been examined. Here we investigated whether a cyclooxygenase-2 (COX-2) inhibitor or diethylcarbamazine (DEC), that is known for its 5-lipoxygenase inhibiting and antioxidant actions, modify the development of PAH in the Sugen 5416/hypoxia (SuHx) rat model. The COX-2 inhibitor SC-58125 had little effect on the right ventricular pressure and did not prevent the development of pulmonary angioobliteration. In contrast, DEC blunted the muscularization of pulmonary arterioles and reduced the number of fully obliterated lung vessels. DEC treatment of SuHx rats, after the lung vascular disease had been established, reduced the degree of PAH, the number of obliterated arterioles and the degree of perivascular inflammation. We conclude that the non-specific anti-inflammatory drug DEC affects developing PAH and is partially effective once angioobliterative PAH has been established.

For many patients with severe pulmonary arterial hypertension, heart failure-and, in particular, right heart failure-is the final chapter of their chronic illness. Targeted therapy for pulmonary hypertension is effective only if the right ventricular ejection fraction is maintained or improved. Because improvement of right heart function and reversal of right heart failure are treatment goals, it is important to investigate the cellular and molecular mechanisms that cause right heart failure. Here, we propose that right ventricular capillary rarefaction is an important hallmark of right heart failure and consider that the "sick lung circulation" and the pressure-overloaded right ventricle constitute a functional unit.

While significant progress has been made to advance our knowledge of microvascular lesion formation, yet the investigation of how stem-like cells may contribute to the pathogenesis of microvascular diseases is still in its infancy. We assessed whether the inhibitor of DNA binding and differentiation 3 (ID3) contributes to the acquisition of a molecular stem cell-like signature in microvascular endothelial cells. The effects of stable ID3 overexpression and SU5416 treatment - a chemical inducer of microvascular lesions, had on the stemness signature were determined by flow cytometry, immunoblot, and immunohistochemistry. Continuous ID3 expression produced a molecular stemness signature consisting of CD133(+) VEGFR3(+) CD34(+) cells. Cells exposed to SU5416 showed positive protein expression of ID3, VEGFR3, CD34 and increased expression of pluripotent transcription factors Oct-4 and Sox-2. ID3 overexpressing cells supported the formation of a 3-D microvascular lesion co-cultured with smooth muscle cells. In addition, in vivo microvascular lesions from SuHx rodent model showed an increased expression of ID3, VEGFR3, and Pyk2 similar to SU5416 treated human endothelial cells. Further investigations into how normal and stem-like cells utilize ID3 may open up new avenues for a better understanding of the molecular mechanisms which are underlying the pathological development of microvascular diseases., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The mechanisms involved in the development of severe angioobliterative pulmonary arterial hypertension (PAH) are multicellular and complex. Many of the features of human severe PAH, including angioobliteration, lung perivascular inflammation, and right heart failure, are reproduced in the Sugen 5416/chronic hypoxia (SuHx) rat model. Here we address, at first glance, the confusing and paradoxical aspect of the model, namely, that treatment of rats with the antiangiogenic vascular endothelial growth factor (VEGF) receptor 1 and 2 kinase inhibitor, Sugen 5416, when combined with chronic hypoxia, causes angioproliferative pulmonary vascular disease. We postulated that signaling through the unblocked VEGF receptor VEGFR3 (or flt4) could account for some of the pulmonary arteriolar lumen-occluding cell growth. We also considered that Sugen 5416-induced VEGFR1 and VEGFR2 blockade could alter the expression pattern of VEGF isoform proteins. Indeed, in the lungs of SuHx rats we found increased expression of the ligand proteins VEGF-C and VEGF-D as well as enhanced expression of the VEGFR3 protein. In contrast, in the failing right ventricle of SuHx rats there was a profound decrease in the expression of VEGF-B and VEGF-D in addition to the previously described reduction in VEGF-A expression. MAZ51, an inhibitor of VEGFR3 phosphorylation and VEGFR3 signaling, largely prevented the development of angioobliteration in the SuHx model; however, obliterated vessels did not reopen when animals with established PAH were treated with the VEGFR3 inhibitor. Part of the mechanism of vasoobliteration in the SuHx model occurs via VEGFR3. VEGFR1/VEGFR2 inhibition can be initially antiangiogenic by inducing lung vessel endothelial cell apoptosis; however, it can be subsequently angiogenic via VEGF-C and VEGF-D signaling through VEGFR3.

Aims: The NLRP3 inflammasome is activated in the ischaemic heart promoting caspase-1 activation, inflammation, and cell death. Ischaemic injury establishes both a priming signal (transcription of inflammasome components) and a trigger (NLRP3 activation). Whether NLRP3 activation, without priming, induces cardiac dysfunction and/or failure is unknown. The aim of this study was to assess the independent and complementary roles of the priming and the triggering signals in the heart, in the absence of ischaemia or myocardial injury., Methods and Results: We used mice with mutant NLRP3 (constitutively active), NLRP3-A350V, under the control of tamoxifen-driven expression of the Cre recombinase (Nlrp3-A350V/CreT mice). The mice were treated for 10 days with tamoxifen before measuring the activity of caspase-1, the effector enzyme in the inflammasome. Tamoxifen treatment induced the inflammasome in the spleen but not in the heart, despite expression of the mutant NLRP3-A350V. The components of the inflammasome were significantly less expressed in the heart compared with the spleen. Subclinical low-dose lipopolysaccharide (LPS; 2 mg/kg) in Nlrp3-A350V/CreT mice induced the expression of the components of the inflammasome (priming), measured using real-time PCR and western blot, leading to the formation of an active inflammasome (caspase-1 activation) in the heart and LV systolic dysfunction while low-dose LPS was insufficient to induce LV systolic dysfunction in wild-type mice (all P < 0.01 for mutant vs. wild-type mice)., Conclusion: The signalling pathway governing the inflammasome formation in the heart requires a priming signal in order for an active NLRP3 to induce caspase-1 activation and LV dysfunction., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.)

Prostacyclin and its analogues improve cardiac output and functional capacity in patients with pulmonary arterial hypertension (PAH); however, the underlying mechanism is not fully understood. We hypothesised that prostanoids have load-independent beneficial effects on the right ventricle (RV). Angio-obliterative PAH and RV failure were induced in rats with a single injection of SU5416 followed by 4 weeks of exposure to hypoxia. Upon confirmation of RV dysfunction and PAH, rats were randomised to 0.1 μg·kg(-1) nebulised iloprost or drug-free vehicle, three times daily for 2 weeks. RV function and treadmill running time were evaluated pre- and post-iloprost/vehicle treatment. Pulmonary artery banded rats were treated 8 weeks after surgery to allow for significant RV hypertrophy. Inhaled iloprost significantly improved tricuspid annulus plane systolic excursion and increased exercise capacity, while mean pulmonary artery pressure and the percentage of occluded pulmonary vessels remained unchanged. Rats treated with iloprost had a striking reduction in RV collagen deposition, procollagen mRNA levels and connective tissue growth factor expression in both SU5416/hypoxia and pulmonary artery banded rats. In vitro, cardiac fibroblasts treated with iloprost showed a reduction in transforming growth factor (TGF)-β1-induced connective tissue growth factor expression, in a protein kinase A-dependent manner. Iloprost decreased TGF-β1-induced procollagen mRNA expression as well as cardiac fibroblast activation and migration. Iloprost significantly induced metalloproteinase-9 gene expression and activity and increased the expression of autophagy genes associated with collagen degradation. Inhaled iloprost improves RV function and reverses established RV fibrosis partially by preventing collagen synthesis and by increasing collagen turnover., (Copyright ©ERS 2015.)

Heart failure (HF) with preserved ejection fraction (HFpEF) is a clinical syndrome of exercise intolerance and/or congestion, in the presence of a left ventricular (LV) ejection fraction within the normal limits (i.e. LVEF>50%). Determining the presence of impaired LV relaxation and/or filling (diastolic dysfunction) in HFpEF is needed to pragmatically to distinguish it from other cardiac and non-cardiac conditions where symptoms are not due to HF. There are multiple mechanisms for diastolic dysfunction ranging from structural abnormalities to functional derangements in HFpEF yet tailored therapies are lacking. Treatments proven effective in HF with systolic dysfunction have failed to show significant benefit in patients with HFpEF, which prognosis remains poor. This review will discuss the challenges inherent to the use of diagnostic criteria for HFpEF, differential diagnosis, prognostic evaluation, and treatment, highlighting the need for more research in this field., (Copyright © 2014. Published by Elsevier Ireland Ltd.)

Survival in patients with pulmonary arterial hypertension (PAH) is closely related to right ventricular (RV) function. Although pulmonary load is an important determinant of RV systolic function in PAH, there remains a significant variability in RV adaptation to pulmonary hypertension. In this report, the authors discuss the emerging concepts of right heart pathobiology in PAH. More specifically, the discussion focuses on the following questions. 1) How is right heart failure syndrome best defined? 2) What are the uderlying molecular mechanisms of the failing right ventricle in PAH? 3) How are RV contractility and function and their prognostic implications best assessed? 4) What is the role of targeted RV therapy? Throughout the report, the authors highlight differences between right and left heart failure and outline key areas of future investigation. (J Am Coll Cardiol 2013;62:D22-33) a 2013 by the American College of Cardiology Foundation).