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International audience; Pulmonary arterial hypertension (PAH) is a progressive and fatal disease characterized by the dysfunction of pulmonary endothelial cells (ECs) and obstructive vascular remodeling. The non-receptor tyrosine kinase c-Abelson (cAbl) plays central roles in regulating cell-cycle arrest, apoptosis, and senescence after cellular stress. We hypothesized that cAbl is down-activated in experimental and human PAH, thus leading to reduced DNA integrity and angiogenic capacity of pulmonary ECs from PAH patients (PAH-ECs). We found cAbl and phosphorylated cAbl levels to be lower in the endothelium of remodeled pulmonary vessels in the lungs of PAH patients than controls. Similar observations were obtained for the lungs of sugen+hypoxia (SuHx) and monocrotaline (MCT) rats with established pulmonary hypertension. These in situ abnormalities were also replicated in vitro, with cultured PAH-ECs displaying lower cAbl expression and activity and an altered DNA damage response and capacity of tube formation. Downregulation of cAbl by RNA-interference in Control-ECs or its inhibition with dasatinib resulted in genomic instability and the failure to form tubes, whereas upregulation of cAbl with DPH reduced DNA damage and apoptosis in PAH-ECs. Finally, we establish the existence of crosstalk between cAbl and bone morphogenetic protein receptor type II (BMPRII). This work identifies the loss of cAbl signaling as a novel contributor to pulmonary EC dysfunction associated with PAH.

Pulmonary arterial hypertension (PAH) is a progressive incurable condition that is characterized by extensive remodeling of the pulmonary circulation, leading to severe right-sided heart failure and death. Similar to other vascular contractile cells, pulmonary arterial smooth muscle cells play central roles in physiological and pathologic vascular remodeling because of their remarkable ability to dynamically modulate their phenotype to ensure contractile and synthetic functions. The dysfunction and molecular mechanisms underlying their contribution to the various pulmonary vascular lesions associated with PAH have been a major focus of research. The aim of this review is to describe the medial and nonmedial origins of contractile cells in the pulmonary vascular wall and present evidence of how they contribute to the onset and progression of PAH. We also highlight specific potential target molecules and discuss future directions that are being explored to widen the therapeutic options for the treatment of PAH.

Previous studies have suggested an association between uric acid (UA) and the severity of pulmonary arterial hypertension (PAH), but it is unknown whether UA contributes to disease pathogenesis.The aim of this study was to determine the prognostic value of circulating UA in the era of current management of PAH and to investigate the role of UA in pulmonary vascular remodelling.Serum UA levels were determined in idiopathic, heritable or anorexigen PAH at baseline and first re-evaluation in the French Pulmonary Hypertension Network. We studied protein levels of xanthine oxidase (XO) and the voltage-driven urate transporter 1 (URATv1) in lungs of control and PAH patients and of monocrotaline (MCT) and Sugen/hypoxia (SuHx) rats. Functional studies were performed using human pulmonary artery smooth muscle cells (PA-SMCs) and two animal models of pulmonary hypertension (PH).High serum UA levels at first follow-up, but not at baseline, were associated with a poor prognosis. Both the generating enzyme XO and URATv1 were upregulated in the wall of remodelled pulmonary arteries in idiopathic PAH patients and MCT and SuHx rats. High UA concentrations promoted a mild increase in cell growth in idiopathic PAH PA-SMCs, but not in control PA-SMCs. Consistent with these observations, oxonic acid-induced hyperuricaemia did not aggravate MCT-induced PH in rats. Finally, chronic treatment of MCT and SuHx rats with benzbromarone mildly attenuated pulmonary vascular remodelling.UA levels in idiopathic PAH patients were associated with an impaired clinical and haemodynamic profile and might be used as a non-invasive indicator of clinical prognosis during follow-up. Our findings also indicate that UA metabolism is disturbed in remodelled pulmonary vascular walls in both experimental and human PAH.

Introduction: Pulmonary endothelial cells (P-ECs) in idiopathic pulmonary arterial hypertension (iPAH) accumulate DNA lesions during the disease progression; however, the mechanisms underlying this phenomenon remain unclear. Since the non-receptor tyrosine kinase c-Abelson (c-Abl) responds to signals from DNA damage and activates apoptosis, we hypothesized that DNA damage accumulation is due to a loss of c-Abl activity in P-ECs derived from PAH patients. Aims and Objectives: To study the role of c-Abl in the loss of genome integrity in iPAH P-ECs. Methods: Primary cultures of human control and iPAH P-ECs were analyzed by comet assay to determine the amount of DNA strand breaks. P-ECs were treated with a c-Abl inhibitor dasatinib (a specific BCR-ABL tyrosine kinase inhibitor), c-Abl siRNA, or DPH (a c-Abl activator) to analyze DNA lesions by comet assays and the activation of DNA repair pathways by Western blotting. Cleaved caspase-3 expression was also measured to determine the level of apoptosis. Results: iPAH P-ECs display a larger amount of DNA strand breaks compared to control P-ECs along with higher apoptosis and impaired c-Abl expression and activity. Treatment of control P-ECs with dasatinib generates more DNA damage and apoptosis than vehicle conditions and alters the DNA repair pathways. Consistent with these observations, downregulation of c-Abl by RNA-interference in control P-ECs resulted in an increase in DNA damage and apoptosis, whereas upregulation of c-Abl with DPH treatment reduced DNA damage and apoptosis levels in iPAH-ECs. Conclusions: Our results demonstrate a central role of c-Abl in the loss of DNA integrity in iPAH P-ECs.

Introduction: Despite increasing evidence suggesting that the Bone Morphogenetic Protein (BMP)-9 signaling pathway is playing a role in the pulmonary hypertension (PH) pathogenesis, the data in the literature are still controversial. Aims and Objectives: To investigate the role of BMP9 signaling pathway in PH pathophysiology. Methods: Bmp9 KO-/- rats were subjected to 3 distinct well characterized experimental PH models: the chronic hypoxia (CHx), monocrotaline (MCT) and Sugen/hypoxia (SuHx) models. Wild-type littermates were used as controls. We then performed transthoracic echocardiography and right heart catheterization as well as histological analyses in these 3 models: 21 days after CHx and MCT treatment and 8 weeks in the SuHx model. Results: While Bmp9 KO-/- rats did not develop any spontaneous phenotype, they were protected against PH induced in our 3 different PH models, compared with their wild-type littermates, as reflected by lower values of mean pulmonary artery pressure (mPAP), total pulmonary vascular resistance (TPVR), and Fulton index. We also found a less pronounced remodeling of the pulmonary arterioles and collagen accumulation in the right ventricle in these Bmp9 KO-/- rats compared to their wild-type littermates. Finally, we found that the in vitro exposure of human pulmonary endothelial cells (ECs) to BMP9 modulates the secretion of pro- and anti-angiogenic factors. These in vitro observations were confirmed in vivo, with Bmp9 KO-/- rats exhibiting increased serum and lung levels of pro-angiogenic factors. Conclusions: BMP9 deficiency does not lead to spontaneous PH, but attenuates the development of experimental PH.

Aims Although right ventricular (RV) function is an important determinant of morbidity and mortality in patients with pulmonary arterial hypertension (PAH), there is no treatment targeting directly the RV. We evaluate the efficacy of sacubitril/valsartan (LCZ 696) as add-on therapy to bosentan in rats with severe pulmonary hypertension (PH). Methods and results Combination therapy of LCZ 696 and bosentan has additive vascular protective effects against the pulmonary vascular remodelling and PH in two preclinical models of severe PH. Compared with monotherapy, co-treatment of LCZ 696 (30 or 68 mg/kg/day for 2 weeks, per os) and bosentan (100 mg/kg/day for 2 weeks, per os) started 7 days after monocrotaline (MCT) injection substantially reduces pulmonary pressures, vascular remodelling, and RV hypertrophy and fibrosis in rats. Consistent with these observations, co-treatment of rats with established PH induced by sugen/hypoxia (SuHx) with LCZ 696 (30 mg/kg/day for 3 weeks, per os) and bosentan (100 mg/kg/day for 3 weeks, per os) started 5 weeks after Sugen injection partially attenuate total pulmonary vascular resistance and cardiovascular structures. We also obtained evidence showing that LCZ 696 has anti-proliferative effect on cultured human pulmonary artery smooth muscle cells derived from patients with idiopathic PAH, an effect that is more pronounced in presence of bosentan. Finally, we found that the plasma levels of atrial natriuretic peptide (ANP) and cyclic guanosine monophosphate (cGMP) are higher in rats co-treated with LCZ 696 (30 mg/kg/day) and bosentan (100 mg/kg/day) than in MCT and SuHx rats treated with vehicle. Conclusion Dual therapy with LCZ 696 plus bosentan proved significantly superior beneficial effect to LCZ 696 or bosentan alone on vascular remodelling and severity of experimental PH.

Leptin is a pleotropic hormone known to regulate a wide range of systemic functions, from satiety to inflammation. Increasing evidence has shown that leptin and its receptor (ObR) are not only expressed in adipose tissue but also in several organs, including the lungs. Leptin levels were first believed to be elevated only in the lungs of obese patients, and leptin was suspected to be responsible for obesity-related lung complications. Aside from obesity, leptin displays many faces in the respiratory system, independently of body weight, as this cytokine-like hormone plays important physiological roles, from the embryogenic state to maturation of the lungs and the control of ventilation. The leptin-signaling pathway is also involved in immune modulation and cell proliferation, and its dysregulation can lead to the onset of lung diseases. This review article addresses the thousand faces of leptin and its signaling in the lungs under physiological conditions and in disease.

Objective: Excessive accumulation of resident cells within the pulmonary vascular wall represents the hallmark feature of the remodeling occurring in pulmonary arterial hypertension (PAH). Furthermore, we have previously demonstrated that pulmonary arterioles are excessively covered by pericytes in PAH, but this process is not fully understood. The aim of our study was to investigate the dynamic contribution of pericytes in PAH vascular remodeling. Approach and Results: In this study, we performed in situ, in vivo, and in vitro experiments. We isolated primary cultures of human pericytes from controls and PAH lung specimens then performed functional studies (cell migration, proliferation, and differentiation). In addition, to follow up pericyte number and fate, a genetic fate-mapping approach was used with an NG2CreER;mT/mG transgenic mice in a model of pulmonary arteriole muscularization occurring during chronic hypoxia. We identified phenotypic and functional abnormalities of PAH pericytes in vitro, as they overexpress CXCR (C-X-C motif chemokine receptor)-7 and TGF (transforming growth factor)-βRII and, thereby, display a higher capacity to migrate, proliferate, and differentiate into smooth muscle-like cells than controls. In an in vivo model of chronic hypoxia, we found an early increase in pericyte number in a CXCL (C-X-C motif chemokine ligand)-12-dependent manner whereas later, from day 7, activation of the canonical TGF-β signaling pathway induces pericytes to differentiate into smooth muscle-like cells. Conclusions: Our findings reveal a pivotal role of pulmonary pericytes in PAH and identify CXCR-7 and TGF-βRII as 2 intrinsic abnormalities in these resident progenitor vascular cells that foster the onset and maintenance of PAH structural changes in blood lung vessels.

International audience; Heightened pulmonary artery smooth muscle cell (PA-SMC) proliferation and migration and dynamic remodeling of the extracellular matrix are hallmark pathogenic features of pulmonary arterial hypertension (PAH). Pirfenidone (PFD) is an orally bioavailable pyridone derivative with antifibrotic, antiinflammatory, and antioxidative properties currently used in the treatment of idiopathic pulmonary fibrosis. We therefore evaluated the efficacy of curative treatments with PFD in the sugen/hypoxia (SuHx) rat model of severe pulmonary hypertension. Treatment with PFD (30 mg/kg per day by mouth 3 times a day for 3 wk) started 5 wk after sugen injection partially reversed established pulmonary hypertension, reducing total pulmonary vascular resistance and remodeling. Consistent with these observations, we found that continued PFD treatment decreases PA-SMC proliferation and levels of extracellular matrix deposition in lungs and right ventricles in SuHx rats. Importantly, PFD attenuated the proproliferative and promigratory potentials of cultured PA-SMCs from patients with idiopathic PAH and their capacity to produce extracellular matrix components. Finally, we found that PFD dose dependently enhanced forkhead box O1 protein levels and its nuclear translocation in cultured idiopathic PAH PA-SMCs and in PFD-treated SuHx rats. PFD appears to be a potential therapy for PAH worthy of investigation and evaluation for clinical use in conjunction with current PAH treatments.-Poble, P.-B., Phan, C., Quatremare, T., Bordenave, J., Thuillet, R., Cumont, A., Huertas, A., Tu, L., Dorfmüller, P., Humbert, M., Ghigna, M.-R., Savale, L., Guignabert, C. Therapeutic effect of pirfenidone in the sugen/hypoxia rat model of severe pulmonary hypertension.

Introduction In pulmonary arterial hypertension (PAH), the current therapies do not target pulmonary vascular remodeling (PVR), the main cause of the disease. Type I cytokine receptors (TypeIR) are known to be overexpressed in PAH pulmonary artery smooth muscle cells (PA-SMCs) and involved in PVR. Aims and objectives To assess whether the regulation of TypeIR intracellular trafficking is altered in PAH, leading to TypeIR overexpression and PVR. Methods We studied TypeIR trafficking through the main regulatory proteins ubiquitin-specific protease 8 (USP8) and ring finger protein (RNF) 41. In PAH patients and in controls, we performed in situ immunostaining in lung samples and western blotting in primary cultures of PA-SMCs isolated from human tissues. We transfected human PA-SMCs with siRNA against USP8 and RNF41 in vitro. In two experimental models, the monocrotaline- and chronic hypoxia-induced PAH, we performed hemodynamic measurements followed by in situ immunostaining and western blotting analysis in lung tissues. Results We showed an increased USP8 and decreased RNF41 expression in PAH lungs compared to controls, and a similar shift in USP8/RNF41 ratio at the protein level in PAH PA-SMCs compared to controls (n = 10). We modulated USP8/RNF41 ratio with siRNAs and restored TypeIR expression and its signalling (n = 5). Consistent with our human in situ and in vitro results, we confirmed the altered USP8/RNF41 ratio in the two in vivo models (n = 8 and n = 5). Conclusions TypeIR intracellular trafficking regulation is altered in PAH patients compared to controls, due to a shift in USP8/RNF41 ratio. Restoring USP8/RNF41 ratio in PA-SMCs may represent a potential target in PAH.

Purpose of review Pulmonary arterial hypertension (PAH) is a hemodynamic state defined by a resting mean pulmonary arterial pressure at or above 25 mmHg with a normal pulmonary capillary wedge pressure, ultimately leading to right heart failure and premature death. Although considerable progress has been made in the development of drug therapies for PAH targeting abnormalities found in the three main pathobiologic pathways (nitric oxide, prostacyclin, and endothelin-1), there is no drug available to specifically stop the progressive cellular accumulation into the pulmonary artery vessel wall. Indeed, this pulmonary vascular remodeling is a key pathological feature in PAH, contributing to the progressive narrowing of the lumen responsible to the functional decline and to the right ventricle hypertrophy and dysfunction. Recent findings Because numerous important discoveries in the PAH pathogenesis have been recently made, our improved understanding of additional pathways in this condition will presumably lead to the development of novel and more powerful therapeutic strategies in the near future. Summary In this review, we highlight some recent biological findings and discuss the opportunities that could lead to the identification of new promising targets in PAH paving the way for future therapeutic strategies.

This review seeks to provide an update of preclinical findings and available clinical data on the chronic persistent inflammation and its direct role on the pulmonary arterial hypertension (PAH) progression. We reviewed the different mechanisms by which the inflammatory and immune pathways contribute to the structural and functional changes occurring in the three vascular compartments: the tunica intima, tunica media, and tunica adventitia. We also discussed how these inflammatory mediator changes may serve as a biomarker of the PAH progression and summarize unanswered questions and opportunities for future studies in this area.

Aims The progressive accumulation of cells in pulmonary vascular walls is a key pathological feature of pulmonary arterial hypertension (PAH) that results in narrowing of the vessel lumen, but treatments targeting this mechanism are lacking. The C-X-C motif chemokine 12 (CXCL12) appears to be crucial in these processes. We investigated the activity of two CXCL12 neutraligands on experimental pulmonary hypertension (PH), using two complementary animal models. Methods and results Male Wistar rats were injected with monocrotaline (MCT) or were subjected to SU5416 followed by 3-week hypoxia to induce severe PH. After PH establishment, assessed by pulsed-wave Doppler echocardiography, MCT-injected or SU5416 plus chronic hypoxia (SuHx) rats were randomized to receive CXCL12 neutraligands chalcone 4 or LIT-927 (100 mg/kg/day), the C-X-C motif chemokine receptor 4 (CXCR4) antagonist AMD3100 (5 mg/kg/day), or vehicle, for 2 or 3 weeks, respectively. At the end of these treatment periods, echocardiographic and haemodynamic measurements were performed and tissue samples were collected for protein expression and histological analysis. Daily treatment of MCT-injected or SuHx rats with established PH with chalcone 4 or LIT-927 partially reversed established PH, reducing total pulmonary vascular resistance, and remodelling of pulmonary arterioles. Consistent with these observations, we found that neutralization of CXCL12 attenuates right ventricular hypertrophy, pulmonary vascular remodelling, and decreases pulmonary artery smooth muscle cell (PA-SMC) proliferation in lungs of MCT-injected rats and SuHx rats. Importantly, CXCL12 neutralization with either chalcone 4 or LIT-927 inhibited the migration of PA-SMCs and pericytes in vitro with a better efficacy than AMD3100. Finally, we found that CXCL12 neutralization decreases vascular pericyte coverage and macrophage infiltration in lungs of both MCT-injected and SuHx rats. Conclusion We report here a greater beneficial effect of CXCL12 neutralization vs. the conventional CXCR4 blockade with AMD3100 in the MCT and SuHx rat models of severe PH, supporting a role for CXCL12 in the progression of vascular complications in PH and opening to new therapeutic options.

Pulmonary arterial hypertension (PAH) is a severe and incurable cardiopulmonary disorder. Research from the past 10 years illustrates the complex and multifactorial aspects of PAH pathophysiology. Furthermore, latest advances in the field have led to a better understanding of the key components underlying this inadequate accumulation of pulmonary vascular cells within the pulmonary arterial walls, leading to pulmonary vascular remodelling. Among the underlying molecular and cellular mechanisms, pulmonary endothelial dysfunction, alterations of the inter-cell communications within the pulmonary arterial walls as well as defects of the inflammatory component and the loss of BMPRII activity play critical roles in the pathogenesis of the disease., Dans l’hypertension artérielle pulmonaire (HTAP), les récentes découvertes physiopathologiques illustrent bien la complexité et l’aspect multifactoriel des mécanismes impliqués dans l’accumulation inadéquate de cellules vasculaires pulmonaires dans les parois des artères pulmonaires. Néanmoins, ces dernières avancées dans le domaine ont aussi permis de mieux comprendre les trois composantes motrices à la base de ce remodelage vasculaire pulmonaire et apportent un éclairage nouveau sur les mécanismes moléculaires et cellulaires sous-jacents. Parmi ces acteurs au centre de la pathogenèse, les perturbations des fonctions de l’endothélium pulmonaire et des processus inflammatoires jouent des rôles critiques, tout comme la perte d’activité du BMPRII et les altérations des communications entre cellules au sein des parois des artères pulmonaires.

Rationale: Although many familial cases of pulmonary arterial hypertension exhibit an autosomal dominant mode of inheritance with the majority having mutations in essential constituents of the BMP (bone morphogenetic protein) signaling, the specific contribution of the long-term loss of signal transduction triggered by the BMPR2 (type 2 BMP receptor) remains poorly characterized. Objective: To investigate the role of BMP9, the main ligand of ALK1 (Activin receptor-like kinase 1)/BMPR2 heterocomplexes, in pulmonary hypertension. Method and Results: The absence of BMP9 in Bmp9 −/− mice and its inhibition in C57BL/6 mice using neutralizing anti-BMP9 antibodies substantially prevent against chronic hypoxia-induced pulmonary hypertension judged by right ventricular systolic pressure measurement, right ventricular hypertrophy, and pulmonary distal arterial muscularization. In agreement with these observations, we found that the BMP9/BMP10 ligand trap ALK1 ECD administered in monocrotaline or Sugen/hypoxia (SuHx) rats substantially attenuate proliferation of pulmonary vascular cells, inflammatory cell infiltration, and regresses established pulmonary hypertension in rats. Our data obtained in human pulmonary endothelial cells derived from controls and pulmonary arterial hypertension patients indicate that BMP9 can affect the balance between endothelin-1, apelin, and adrenomedullin. We reproduced these in vitro observations in mice chronically exposed to hypoxia, with Bmp9 −/− mice exhibiting lower mRNA levels of the vasoconstrictor peptide ET-1 (endothelin-1) and higher levels of the 2 potent vasodilator factors apelin and ADM (adrenomedullin) compared with Bmp9 +/+ littermates. Conclusions: Taken together, our data indicate that the loss of BMP9, by deletion or inhibition, has beneficial effects against pulmonary hypertension onset and progression.

Coronavirus disease 2019 (COVID-19) represents a public health crisis of pandemic proportions. Caused by SARS-CoV-2, which stands for severe acute respiratory syndrome (SARS) coronavirus 2, the symptoms most commonly reported include cough, fever, and shortness of breath, but also extra-pulmonary symptoms, such as neurological and gastroenterological manifestations.

Uric acid (UA) has been identified as a prognostic factor in pulmonary arterial hypertension (PAH). However, the causal mechanisms linking elevated UA levels to the vascular remodeling of pulmonary arteries in experimental and human PAH are still unsettled. The aim of the study was to investigate the pathophysiological contribution of UA and its voltage-driven urate transporter 1 (URATv1) in experimental and human PAH. We examined serum UA levels in patients with idiopathic PAH and in rats with PH using two animal models (sugen-hypoxia and monocrotaline-induced PH). Expression patterns of xanthine oxidase (XO) and URATv1 were investigated in cultured human pulmonary artery-smooth muscle cells (PA-SMCs) as well as in whole lung homogenates from PAH patients and rats. Effect of hyperuricemia induced by oxionic acid on chronic hypoxia-induced PH was also studied. Finally, effects of an uricosuric agent, benzbromarone, on pulmonary vascular remodeling and experimental PH were determined. Idiopathic PAH patients and rats with PH exhibit increased levels of serum UA. We identified an overexpression XO and URATv1 in cultured iPAH PA-SMCs as well as in the smooth muscle from remodeled pulmonary arteries of rodents and humans. We also found that UA promotes the proliferation of cultured human PA-SMCs, a phenomenon abolished with benzbromarone. Whereas hyperuricemia induced by oxionic acid increases the susceptibility to chronic hypoxia-induced PH, benzbroramone prevents and reverses established PH in the MCT and SuHX rat models. Our results reveal a direct role of UA in PA-SMC accumulation in experimental and human PAH, highlighting the potential interests of uricosuric agent in these severe conditions.

Pulmonary hypertension (PH) is defined by a mean pulmonary artery pressure of at least 25 mmHg during resting right heart catheterization. PH is not a single disease, but a haemodynamic feature found in a rather large group of diseases that can result from pre-capillary (arterial) or post-capillary (venous) pathophysiological mechanisms. The current PH clinical classification gathers together groups of PH that share similar haemodynamic criteria and types of pulmonary vascular lesions in order to optimize therapeutic approaches, to predict patient outcomes, and facilitate research strategies. However, the five different PH groups exhibit several common points and key regulators are shared, and they include a combination of the following in varying degrees of importance: pulmonary endothelial dysfunction, significant accumulation of pulmonary vascular cells, excessive lung recruitment of inflammatory cells, and the presence of specific genetic mutations and environmental factors. This chapter aims to outline the key cellular and molecular mechanisms contributing to the sustained remodelling of the pulmonary vascular bed in PH and discuss the urgent need of additional therapies directly targeting the pulmonary vascular remodelling in the future management of PH.

Pulmonary arterial hypertension (PAH) is characterized by a progressive accumulation of pulmonary artery smooth muscle cells (PA-SMCs) in pulmonary arterioles leading to the narrowing of the lumen, right heart failure, and death. Although most studies have supported the notion of a role for IL-6/glycoprotein 130 (gp130) signaling in PAH, it remains unclear how this signaling pathway determines the progression of the disease. Here, we identify ectopic upregulation of membrane-bound IL-6 receptor (IL6R) on PA-SMCs in PAH patients and in rodent models of pulmonary hypertension (PH) and demonstrate its key role for PA-SMC accumulation in vitro and in vivo. Using Sm22a-Cre Il6rfl/fl, which lack Il6r in SM22A-expressing cells, we found that these animals are protected against chronic hypoxia-induced PH with reduced PA-SMC accumulation, revealing the potent pro-survival potential of membrane-bound IL6R. Moreover, we determine that treatment with IL6R-specific antagonist reverses experimental PH in two rat models. This therapeutic strategy holds promise for future clinical studies in PAH.

Macrophage migration inhibitory factor (MIF) is a key pleiotropic mediator and a promising therapeutic target in cancer as well as in several inflammatory and cardiovascular diseases including pulmonary arterial hypertension (PAH). Here, a novel series of N-(phenylmethyl)-benzoxazol-2-thiones 5-32 designed to target the MIF tautomerase active site was synthesized and evaluated for its effects on cell survival. Investigation of structure-activity relationship (SAR) particularly at the 5-position of the benzoxazole core led to the identification of 31 that potently inhibits cell survival in DU-145 prostate cancer cells and pulmonary endothelial cells derived from patients with idiopathic PAH (iPAH-ECs), two cell lines for which survival is MIF-dependent. Molecular docking studies helped to interpret initial SAR related to MIF tautomerase inhibition and propose preferred binding mode for 31 within the MIF tautomerase active site. Interestingly, daily treatment with 31 started 2 weeks after a subcutaneous monocrotaline injection regressed established pulmonary hypertension in rats.

An obesity paradox, wherein patients who are obese have lower mortality, has been described in cardiopulmonary diseases, including pulmonary arterial hypertension (PAH). Our objective was to determine whether obesity and BMI are associated with mortality in patients with PAH.We assessed incident patients with idiopathic, drug-induced, and heritable PAH from the French Pulmonary Hypertension Network registry. Cox regression and Kaplan-Meier analysis were used to assess the association between BMI and obesity with all-cause mortality.Of 1,255 patients included, 30% were obese. A higher proportion of women (65.1% vs 53.4%, P .01), drug-induced PAH (28.9% vs 9.2%, P .01), systemic hypertension, diabetes, and hypothyroidism were present in the obese group. More obese patients were in New York Heart Association class III (66.4% vs 57.1%), fewer were class IV (11.8% vs 16.9%, P .01), and 6-min walk distance was lower (276 ± 121 vs 324 ± 146, P .01). Right atrial pressure, pulmonary wedge pressure, and cardiac index were higher, whereas pulmonary vascular resistance was lower in patients who were obese. Neither BMI (hazard ratio [HR], 0.99; 95% CI, 0.97-1.01; P = .41) nor obesity (HR, 1.0; 95% CI, 0.99-1.01; P = .46) were associated with mortality in multivariable analyses. There was a significant interaction between age and obesity such that mortality increased among patients 65 years of age who were morbidly obese (HR, 3.01; 95% CI, 1.56-5.79; P = .001).Obesity was not associated with mortality in the overall population, but there was an age-obesity interaction with increased mortality among young patients who were morbidly obese. These results have implications for active weight management in younger patients who are morbidly obese who are otherwise candidates for lung transplantation.

Pleural effusion is a frequent side-effect of dasatinib, a second-generation tyrosine kinase inhibitor used in the treatment of chronic myelogenous leukaemia. However, the underlying mechanisms remain unknown. We hypothesised that dasatinib alters endothelial integrity, resulting in increased pulmonary vascular endothelial permeability and pleural effusion.To test this, we established the first animal model of dasatinib-related pleural effusion, by treating rats with a daily regimen of high doses of dasatinib (10 mg·kg−1·day−1for 8 weeks).Pleural ultrasonography revealed that rats chronically treated with dasatinib developed pleural effusion after 5 weeks. Consistent with thesein vivoobservations, dasatinib led to a rapid and reversible increase in paracellular permeability of human pulmonary endothelial cell monolayers as reflected by increased macromolecule passage, loss of vascular endothelial cadherin and zonula occludens-1 from cell–cell junctions, and the development of actin stress fibres. These results were replicated using human umbilical vein endothelial cells and confirmed by decreased endothelial resistance. Interestingly, we demonstrated that this increased endothelial permeability is a reactive oxygen species (ROS)-dependent mechanismin vitroandin vivousing a cotreatment with an antioxidant agent,N-acetylcysteine.This study shows that dasatinib alters pulmonary endothelial permeability in a ROS-dependent mannerin vitroandin vivoleading to pleural effusion.

Pulmonary arterial hypertension (PAH) is a disorder in which mechanical obstruction of the pulmonary vascular bed is largely responsible for the rise in mean pulmonary arterial pressure, resulting in a progressive functional decline despite current available therapeutic options. The fundamental pathogenetic mechanisms underlying this disorder include pulmonary vasoconstriction, in situ thrombosis, medial hypertrophy, and intimal proliferation, leading to occlusion of the small to mid-sized pulmonary arterioles and the formation of plexiform lesions. Several predisposing or promoting mechanisms that contribute to excessive pulmonary vascular remodeling in PAH have emerged, such as altered crosstalk between cells within the vascular wall, sustained inflammation and dysimmunity, inhibition of cell death, and excessive activation of signaling pathways, in addition to the impact of systemic hormones, local growth factors, cytokines, transcription factors, and germline mutations. Although the spectrum of therapeutic options for PAH has expanded in the last 20 years, available therapies remain essentially palliative. However, over the past decade, a better understanding of new key regulators of this irreversible pulmonary vascular remodeling has been obtained. This review examines the state-of-the-art potential new targets for innovative research in PAH, focusing on (1) the crosstalk between cells within the pulmonary vascular wall, with particular attention to the role played by dysfunctional endothelial cells; (2) aberrant inflammatory and immune responses; (3) the abnormal extracellular matrix function; and (4) altered BMPRII/KCNK3 signaling systems. A better understanding of novel pathways and therapeutic targets will help in the designing of new and more effective approaches for PAH treatment.

Introduction: C-X-C motif chemokine 12 (CXCL12) can directly control cell proliferation, migration and differentiation via interaction with either CXCR4 or CXCR7, and represents a promising target in pulmonary hypertension (PH). However, the efficacy of a CXCL12 neutraligand has never been tested in animal models of severe PH. Objective: To test and compare the efficacy of a CXCL12 neutraligand, chalcone-4, versus a CXCR4 antagonist, AMD3100, in the Sugen 5416/ hypoxia (SuHx) rat model, in a curative approach. Methods & Results: Height weeks after the Sugen 5416 administration, a substantial decrease in values of total pulmonary vascular resistance and of Fulton index (assessing right ventricular hypertrophy) were found in SuHx rats treated with chalcone-4 (100mg/kg/day for 2 weeks) and AMD3100 (5mg/kg/day for 2 weeks) when compared with the SuHx rats treated with vehicle. Interestingly, a substantial increase in values of cardiac output in SuHx rats treated with chalcone-4 was found when compared with the SuHx rats treated with AMD3100. Consistent with these observations, chalcone-4 and AMD3100 substantially attenuated the pulmonary vascular remodeling and the progressive narrowing of pulmonary arteries in the SuHx rat model. Conclusions: We report here a greater beneficial effect of chalcone-4 than AMD3100 treatment in the SuHx rat model of severe PH, supporting a role for CXCL12 in the progression of vascular complications in PH and opening to new therapeutic options.

Heterozygous germline mutations in the Bone Morphogenetic Protein Receptor type 2 (BMPR2) gene have been identified as critical genetic factors predisposing to pulmonary arterial hypertension (PAH) development. At the endothelial cell surface, BMPRII forms heterocomplexes with its co-receptor activin receptor like kinase 1 (ALK1), which are bound by the ligand BMP9, a promising therapeutic target in PAH. Therefore, a better knowledge on the contribution of BMP9 and its signaling pathway to the pulmonary vascular remodeling is clearly needed. We have used Bmp9-KO mice, that are viable and fertile, and two experimental models of pulmonary hypertension: the chronic hypoxia (CHx) and the monocrotaline pyrrole (MCTp). We found that Bmp9-KO mice developed mild increase in right ventricular systolic pressure (RVSP) in room air when compared with wildtype (WT) littermates. Surprisingly, we found that they are less susceptible to develop CHx- and MCTp-induced PH, with significantly lower values in RVSP, right ventricular hypertrophy (RVH), assessed by the Fulton index and pulmonary-artery muscularization when compared with WT. Consistent with these findings, mice treated with an anti–BMP9 neutralizing antibody and rats treated with a soluble ALK1/extracellular domain (ECD) Fc-fusion protein were protected against the increase in RVSP, RVH and muscularization of pulmonary arteries induced by experimental PAH models. Taken together, our data indicate that the loss of BMP9, by deletion or inhibition, protects rodents against the development of experimental PAH. These findings are apparently counter-intuitive and further studies are needed for a better understanding of BMP9 signaling pathway in PAH.

Background: Despite the deleterious health effects of obesity, an obesity paradox has been described in many diseases, including in heterogeneous populations with pulmonary hypertension. Whether obesity is associated with better outcomes in idiopathic (IPAH), drug and toxin-induced (DPAH) or heritable pulmonary arterial hypertension (HPAH) is not known. Methods: We assessed 1363 incident patients with IPAH, DPAH, and HPAH from the French Pulmonary Hypertension Registry. Cox proportional hazards regression was used to assess the effect of obesity on the risk of death or lung transplantation. Obesity was defined as body mass index (BMI)>30 kg/m2. Results: The prevalence of obesity was 30.7%. There was a higher proportion of females (66.6% vs 53.4%, p Conclusions: We found no association between obesity and survival in a large cohort of incident IPAH, DPAH and HPAH patients. Previous evidence of an obesity paradox in pulmonary hypertension may be related to other confounding factors.

Pulmonary arterial hypertension (PAH) corresponds to a heterogeneous group of severe clinical conditions characterized by precapillary pulmonary hypertension (PH) diagnosed when mean pulmonary artery pressure equals or exceeds 25 mm Hg at rest with normal pulmonary artery wedge pressure (≤15 mm Hg). According to the current clinical classification, PAH can be idiopathic (IPAH), heritable, drug or toxin induced, or associated with other diseases (eg, connective tissue diseases [CTDs], congenital heart diseases, HIV infection, and portal hypertension).1 PAH has a complex and multifactorial pathogenesis in which excessive migration and proliferation of pulmonary vascular cells (ie, endothelial cells [ECs] and smooth muscle cells [SMCs]) and dysregulated immune responses are critical contributors to the inappropriate pulmonary vascular remodeling. PAH is a fatal condition leading to right heart failure and death within 2 to 3 years after diagnosis if left untreated. During the last decade, therapeutic options for the treatment of this disease have improved exercise capacity, quality of life, and long-term outcomes. However, there is currently no cure available, and further insight into the disease pathophysiology is needed to advance drug development and to improve patient management. It is now widely accepted that altered immune mechanisms play a significant role in PAH by recruiting inflammatory cells, remodeling the pulmonary vasculature, and promoting autoimmune responses.2–4 Inflammation is a general term for the local accumulation of fluid, plasma proteins, and white blood cells that is initiated by physical injury, infection, or a local immune response. These phenomena represent the innate immune response. The innate immune response contributes to the activation of adaptive immunity, which is the response of antigen-specific lymphocytes to antigen, including the development of immunologic memory. The unique features of adaptive immunity, based on clonal selection of lymphocytes bearing antigen-specific receptors, provide the ability to recognize all pathogens specifically …

Erythrocyte-endothelial interaction is especially pronounced in the lung microvasculature and altered red blood cell (RBC) membrane structure have been demonstrated to induce endothelial cell (EC) dysfunction in several systemic diseases and to be associated with increased risk of cardiovascular disease development. We are questioning here whether RBCs are altered in PAH and could contribute to P-EC dysfunction leading to PAH development and/or progression. In addition, we are investigating whether changes in RBCs are clinically relevant. To test this hypothesis, we withdrew blood samples from PAH patients (n=40) and controls (n=15) and performed automated blood count analyses to determine RBC distribution width (RDW). Next, we isolated RBCs by centrifugation and identified them by flow cytometry, using the RBC surface marker CD235a. Then, we measured by flow cytometry structural membrane protein expression of CD47 and phosphatidylserine (PS) and the level of advanced glycation end product (AGE) production. We found an increased RDW values in PAH patients, which inversely correlate with the 6 minute walk test distance (r=-0.53, p Our data indicate that RBCs in PAH patients are altered in size, structure and function when compared with controls. Further studies are needed to investigate the mechanisms underlying these RBC abnormalities in PAH and to precise their clinical relevance as well as their contribution in P-EC dysfunction.

Background: Increased levels of uric acid (UA) in serum of patients with pulmonary arterial hypertension (PAH) are associated with severity and clinical outcomes. However, the pathophysiological contribution of UA in pulmonary vascular remodeling associated with PAH remains unknown. Objectives: To study pathophysiological roles of UA in experimental and human PAH and to evaluate the translational potential of benzbromarone, an inhibitor against UA transporter URATv1. Methods: We examined serum UA level and the expression pattern of URATv1 in cultured pulmonary artery smooth muscle cells (PA-SMCs) and in lungs of 10 controls (CTR) and 10 patients with idiopathic PAH (IPAH). In addition, the preventive and curative effects of benzbromarone were tested in two experimental models of pulmonary hypertension (PH). Results: In IPAH, we found elevated levels of serum UA and a strong immunoreactivity for URATv1 in the media of remodeled pulmonary arteries and cultured PA-SMCs of IPAH patients when compared with controls. These findings were also replicated in vivo with high in situ levels of URATv1 in PA-SMCs of PH rats. Consistent with these findings, we also demonstrated in vitro that the upregulation of URATv1 contributes to an increased proliferative response to UA in IPAH PA-SMCs when compared with CTR cells, a phenomenon abolished with benzbromarone. Finally, we found that benzbromarone partially prevented and reversed established PH in the monocrotaline and SU5416+hypoxia rat models. Conclusions: Our results support the possibility that the blockade of UA transporter may represent promising novel approaches for treatment of PAH.

Pulmonary arterial hypertension (PAH) is a life-threatening disease that can be induced by dasatinib, an orally bioavailable dual Src/BCR/ABL tyrosine kinase inhibitor used in the treatment of chronic myelogenous leukaemia (CML). Today, key questions remain regarding the long-term evolution of dasatinib-induced PAH and the mechanism(s) involved. Here, we demonstrate that chronic dasatinib therapy causes pulmonary endothelial damage in humans and rodents, in contrast to chronic imatinib treatment. We found that rats pretreated with dasatinib, but not with imatinib, exhibit attenuated hypoxic pulmonary vasoconstriction (HPV) responses and increased susceptibility to experimental pulmonary hypertension (PH). Furthermore, in vivo and in vitro observations show that dasatinib treatment induces pulmonary endothelial cell apoptosis and induction of endoplasmic reticulum stress, in a dose dependent manner, in contrast to imatinib. We also demonstrate that dasatinib-induced endothelial cell dysfunction is mediated through production of reactive oxygen species (ROS), independently of Src family kinases. Consistently with our findings, we found significant elevations of markers of endothelial dysfunction or damage in the serum of CML patients treated with dasatinib when compared with CML patients treated with imatinib. Collectively, we report here that dasatinib causes pulmonary endothelial damage and induction of ER stress via ROS production, leading to increased susceptibility to PH development.

Pulmonary arterial hypertension (PAH) is a life-threatening disease that can be induced by dasatinib, a dual Src and BCR-ABL tyrosine kinase inhibitor that is used to treat chronic myelogenous leukemia (CML). Today, key questions remain regarding the mechanisms involved in the long-term development of dasatinib-induced PAH. Here, we demonstrated that chronic dasatinib therapy causes pulmonary endothelial damage in humans and rodents. We found that dasatinib treatment attenuated hypoxic pulmonary vasoconstriction responses and increased susceptibility to experimental pulmonary hypertension (PH) in rats, but these effects were absent in rats treated with imatinib, another BCR-ABL tyrosine kinase inhibitor. Furthermore, dasatinib treatment induced pulmonary endothelial cell apoptosis in a dose-dependent manner, while imatinib did not. Dasatinib treatment mediated endothelial cell dysfunction via increased production of ROS that was independent of Src family kinases. Consistent with these findings, we observed elevations in markers of endothelial dysfunction and vascular damage in the serum of CML patients who were treated with dasatinib, compared with CML patients treated with imatinib. Taken together, our findings indicate that dasatinib causes pulmonary vascular damage, induction of ER stress, and mitochondrial ROS production, which leads to increased susceptibility to PH development.

Pulmonary arterial hypertension (PAH) is a disorder in which mechanical obstruction of the pulmonary vascular bed is largely responsible for the rise in mean pulmonary arterial pressure (mPAP), resulting in a progressive functional decline despite current available therapeutic options. There are multiple mechanisms predisposing to and/or promoting the aberrant pulmonary vascular remodeling in PAH, and these involve not only altered crosstalk between cells within the vascular wall but also sustained inflammation and dysimmunity, cell accumulation in the vascular wall and excessive activation of some growth factor-stimulated signaling pathways, in addition to the interaction of systemic hormones, local growth factors, cytokines, and transcription factors. Heterozygous germline mutations in the bone morphogenetic protein receptor, type-2 (BMPR2) gene, a gene encoding a receptor for the transforming growth factor (TGF)-β superfamily, can predispose to the disease. Although the spectrum of therapeutic options for PAH has expanded in the last 20 years, available therapies remain essentially palliative. Over the past decade, however, a better understanding of key regulators of this irreversible remodeling of the pulmonary vasculature has been obtained. New and more effective approaches are likely to emerge. The present article profiles the innovative research into novel pathways and therapeutic targets that may lead to the development of targeted agents in PAH.

Pulmonary arterial hypertension (PAH) is a disorder in which mechanical obstruction of the pulmonary vascular bed is largely responsible for the rise in mean pulmonary arterial pressure (mPAP), resulting in a progressive functional decline despite current available therapeutic options. There are multiple mechanisms predisposing to and/or promoting the aberrant pulmonary vascular remodeling in PAH, and these involve not only altered crosstalk between cells within the vascular wall but also sustained inflammation and dysimmunity, cell accumulation in the vascular wall and excessive activation of some growth factor-stimulated signaling pathways, in addition to the interaction of systemic hormones, local growth factors, cytokines, and transcription factors. Heterozygous germline mutations in the bone morphogenetic protein receptor, type-2 (BMPR2) gene, a gene encoding a receptor for the transforming growth factor (TGF)-β superfamily, can predispose to the disease. Although the spectrum of therapeutic options for PAH has expanded in the last 20 years, available therapies remain essentially palliative. Over the past decade, however, a better understanding of key regulators of this irreversible remodeling of the pulmonary vasculature has been obtained. New and more effective approaches are likely to emerge. The present article profiles the innovative research into novel pathways and therapeutic targets that may lead to the development of targeted agents in PAH.

Pulmonary arterial hypertension (PAH) is a progressive and fatal disease characterized by pulmonary arterial muscularization due to excessive pulmonary vascular cell proliferation and migration, a phenotype dependent upon growth factors and activation of receptor tyrosine kinases (RTKs). p130(Cas) is an adaptor protein involved in several cellular signaling pathways that control cell migration, proliferation, and survival.We hypothesized that in experimental and human PAH p130(Cas) signaling is overactivated, thereby facilitating the intracellular transmission of signal induced by fibroblast growth factor (FGF)2, epidermal growth factor (EGF), and platelet-derived growth factor (PDGF).In patients with PAH, levels of p130(Cas) protein and/or activity are higher in the serum, in the walls of distal pulmonary arteries, in cultured smooth muscle cells (PA-SMCs), and in pulmonary endothelial cells (P-ECs) than in control subjects. These abnormalities in the p130(Cas) signaling were also found in the chronically hypoxic mice and monocrotaline-injected rats as models of human PAH. We obtained evidence for the convergence and amplification of the growth-stimulating effect of the EGF-, FGF2-, and PDGF-signaling pathways via the p130(Cas) signaling pathway. We found that daily treatment with the EGF-R inhibitor gefitinib, the FGF-R inhibitor dovitinib, and the PDGF-R inhibitor imatinib started 2 weeks after a subcutaneous monocrotaline injection substantially attenuated the abnormal increase in p130(Cas) and ERK1/2 activation and regressed established pulmonary hypertension.Our findings demonstrate that p130(Cas) signaling plays a critical role in experimental and idiopathic PAH by modulating pulmonary vascular cell migration and proliferation and by acting as an amplifier of RTK downstream signals.

Pulmonary hypertension (PH) is defined as an increase in mean pul- monary arterial pressure above 25 mmHg. Pulmonary vasoconstriction, cellular proliferation, inflammation, and oxidative stress are involved in the patho- physiology of PH. Since hypomagnesemia was reported to promote endothelial cell dysfunction leading to inflammation and oxidative stress, we investi- gated the potential involvement of magnesium (Mg) deficiency in experimental and human PH. Our results indicate that Mg deficiency has no impact on hypoxia-induced PH development or severity, and that no reduction in Mg plasma concentration was observed in patients with severe pulmonary arte- rial hypertension. Thus, hypomagnesemia does not appear to play a role in the pathophysiology of experimental and human pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling of the precapillary pulmonary arteries, with excessive proliferation of vascular cells. Although the exact pathophysiology remains unknown, there is increasing evidence to suggest an important role for inflammation. Firstly, pathologic specimens from patients with PAH reveal an accumulation of perivascular inflammatory cells, including macrophages, dendritic cells, T and B lymphocytes, and mast cells. Secondly, circulating levels of certain cytokines and chemokines are elevated, and these may correlate with a worse clinical outcome. Thirdly, certain inflammatory conditions such as connective tissue diseases are associated with an increased incidence of PAH. Finally, treatment of the underlying inflammatory condition may alleviate the associated PAH. Underlying pathologic mechanisms are likely to be "multihit" and complex. For instance, the inflammatory response may be regulated by bone morphogenetic protein receptor type 2 (BMPR II) status, and, in turn, BMPR II expression can be altered by certain cytokines. Although antiinflammatory therapies have been effective in certain connective-tissue-disease-associated PAH, this approach is untested in idiopathic PAH (iPAH). The potential benefit of antiinflammatory therapies in iPAH is of importance and requires further study.

Shedding of the extracellular domain of cytokine receptors allows the diffusion of soluble receptors into the extracellular space; these then bind and neutralize their cytokine ligands, thus dampening inflammatory responses. The molecular mechanisms that control this process, and the extent to which shedding regulates cytokine-induced microvascular inflammation, are not well defined. Here, we used real-time confocal microscopy of mouse lung microvascular endothelium to demonstrate that mitochondria are key regulators of this process. The proinflammatory cytokine soluble TNF-α (sTNF-α) increased mitochondrial Ca2+, and the purinergic receptor P2Y2 prolonged the response. Concomitantly, the proinflammatory receptor TNF-α receptor-1 (TNFR1) was shed from the endothelial surface. Inhibiting the mitochondrial Ca2+ increase blocked the shedding and augmented inflammation, as denoted by increases in endothelial expression of the leukocyte adhesion receptor E-selectin and in microvascular leukocyte recruitment. The shedding was also blocked in microvessels after knockdown of a complex III component and after mitochondria-targeted catalase overexpression. Endothelial deletion of the TNF-α converting enzyme (TACE) prevented the TNF-α receptor shedding response, which suggests that exposure of microvascular endothelium to sTNF-α induced a Ca2+-dependent increase of mitochondrial H2O2 that caused TNFR1 shedding through TACE activation. These findings provide what we believe to be the first evidence that endothelial mitochondria regulate TNFR1 shedding and thereby determine the severity of sTNF-α-induced microvascular inflammation.

The long-term effects of chronic blood exchange transfusions (BETs) on pre-capillary pulmonary hypertension complicating sickle cell disease (SCD) are unknown.13 homozygous SS SCD patients suffering from pre-capillary pulmonary hypertension and treated by chronic BETs were evaluated retrospectively. Assessments included haemodynamics, New York Heart Association Functional Class (NYHA FC), 6-min walk distance (6MWD) and blood tests.Before initiating BETs, all patients were NYHA FC III or IV, median (range) 6MWD was 223 (0–501) m and median (range) pulmonary vascular resistance (PVR) was 3.7 (2–12.5) Wood Units. After a median number of 4 BET sessions, all patients had improved to NYHA FC II or III. Significant improvements in haemodynamics were observed, including a decrease in PVR (p=0.01). There was a trend to higher 6MWD (p=0.09). Median (range) follow-up time after initiation of BETs was 25 (6–53) months. During this period, two patients decided to stop BETs. One of them died from acute right heart failure and the other experienced worsening pulmonary hypertension. Two other patients died during follow-up at 25 and 54 months after BET initiation.Chronic BETs may be a potential therapeutic option in pre-capillary pulmonary hypertension complicating SCD, leading to significant clinical and haemodynamic improvements. These data must be confirmed in a prospective study.

J Appl Physiol. 2010 Jul;109(1):60-7. Epub 2010 May 6. Hemopoietic and angiogenetic progenitors in healthy athletes: different responses to endurance and maximal exercise. Bonsignore MR, Morici G, Riccioni R, Huertas A, Petrucci E, Veca M, Mariani G, Bonanno A, Chimenti L, Gioia M, Palange P, Testa U. SourceBiomedical Department, Internal and Specialistic Medicine (DIBIMIS), Section of Pneumology, University of Palermo, Via Trabucco, 180, 90146 Palermo, Italy. marisa@ibim.cnr.it Abstract The effects of endurance or maximal exercise on mobilization of bone marrow-derived hemopoietic and angiogenetic progenitors in healthy subjects are poorly defined. In 10 healthy amateur runners, we collected venous blood before, at the end of, and the day after a marathon race (n = 9), and before and at the end of a 1.5-km field test (n = 8), and measured hemopoietic and angiogenetic progenitors by flow cytometry and culture assays, as well as plasma or serum concentrations of several cytokines/growth factors. After the marathon, CD34(+) cells were unchanged, whereas clonogenetic assays showed decreased number of colonies for both erythropoietic (BFU-E) and granulocyte-monocyte (CFU-GM) series, returning to baseline the morning post-race. Conversely, CD34(+) cells, BFU-E, and CFU-GM increased after the field test. Angiogenetic progenitors, assessed as CD34(+)KDR(+) and CD133(+)VE-cadherin(+) cells or as adherent cells in culture expressing endothelial markers, increased after both endurance and maximal exercise but showed a different pattern between protocols. Interleukin-6 increased more after the marathon than after the field test, whereas hepatocyte growth factor and stem cell factor increased similarly in both protocols. Plasma levels of angiopoietin (Ang) 1 and 2 increased after both types of exercise, whereas the Ang-1-to-Ang-2 ratio or vascular endothelial growth factor-A were little affected. These data suggest that circulating hemopoietic progenitors may be utilized in peripheral tissues during prolonged endurance exercise. Endothelial progenitor mobilization after exercise in healthy trained subjects appears modulated by the type of exercise. Exercise-induced increase in growth factors suggests a physiological trophic effect of exercise on the bone marrow. PMID:20448032[PubMed - indexed for MEDLINE]

The European Respiratory Society (ERS) Research Seminar entitled “Pulmonary vascular endothelium: orchestra conductor in respiratory diseases - highlights from basic research to therapy” brought together international experts in dysfunctional pulmonary endothelium, from basic science to translational medicine, to discuss several important aspects in acute and chronic lung diseases. This review will briefly sum up the different topics of discussion from this meeting which was held in Paris, France on October 27–28, 2016. It is important to consider that this paper does not address all aspects of endothelial dysfunction but focuses on specific themes such as: 1) the complex role of the pulmonary endothelium in orchestrating the host response in both health and disease (acute lung injury, chronic obstructive pulmonary disease, high-altitude pulmonary oedema and pulmonary hypertension); and 2) the potential value of dysfunctional pulmonary endothelium as a target for innovative therapies.

Background: Interleukin (IL)-6 has been linked to the prognosis of pulmonary arterial hypertension (PAH). However, precise contributions of IL-6 and its signaling system to PAH progression is still obscure. Objectives: To study pathogenic roles of IL-6 cis- and trans-signaling in experimental and human PAH and to evaluate the translational potential of IL-6 signaling inhibition. Methods: We examined the global expression pattern of key actors of the IL-6 signaling in human lung tissues, blood samples and cultured pulmonary artery-smooth muscle cells (PA-SMCs) of 10 controls and 10 idiopathic PAH (IPAH) patients. In addition, two complementary animal models of pulmonary hypertension (PH) have been studied: the monocrotaline and SU5416 plus chronic hypoxia rat models. Results: In IPAH, serum levels of IL-6 and soluble IL-6 receptors (sIL-6R) proteins were higher than in control subjects. We also found stronger immunoreactivity for IL-6R, p-STAT3 and myeloid leukemia-cell protein 1 (Mcl-1, a downstream target of IL-6) in the media of remodeled pulmonary arteries and cultured PA-SMCs of IPAH patients compared with controls. These abnormalities in the IL-6/IL-6R signaling were also histologically found in the two rat models. Consistent with these findings, we also found that IL-6 with or without sIL-6R could substantially increase p-STAT3 and the anti-apoptotic Mcl-1 protein in cultured IPAH PA-SMCs compared with control cells. These effects were totally abolished in the presence of IL-6R neutralizing antibodies and an IL-6R antagonist. Finally, we found that daily treatment with IL-6R antagonist started 1 week after a subcutaneous monocrotaline injection substantially attenuates the abnormal increase in p-STAT3 and Mcl-1 and regresses established PH. Conclusions: We demonstrate here that anti-IL-6R strategies may represent promising novels anti-proliferative and anti-inflammatory approaches for treatment of PAH.

International audience; BACKGROUND:Pulmonary arterial hypertension (PAH) encompasses a group of conditions with distinct causes. Immunologic disorders are common features of all forms of PAH and contributes to both disease susceptibility and progression. Regulatory T lymphocytes (Treg) are dysfunctional in patients with idiopathic PAH (iPAH) in a leptin-dependent manner. However, it is not known whether these abnormalities are specific to iPAH. Hence, we hypothesized that (1) Treg dysfunction is also present in heritable (hPAH) and connective tissue disease-associated PAH (CTD-PAH); (2) defective leptin-dependent signaling is present in hPAH and CTD-PAH and could contribute to Treg dysfunction; (3) modulating the leptin axis in vivo could protect against Treg dysfunction; and (4) restoration of Treg activity could limit or reverse experimental chronic hypoxia-induced pulmonary hypertension in vivo.METHODS:We analyzed 62 patients with PAH (30 with iPAH, 18 with hPAH, and 14 with CTD-PAH), 7 patients with CTD without PAH, and 20 healthy control subjects.RESULTS:Our results indicate that Treg are dysfunctional in all PAH forms tested, as well as in patients with CTD without PAH. Importantly, the leptin axis is crucial in Treg dysfunction in patients with iPAH and those with CTD (with or without PAH), whereas in patients with hPAH, Treg are altered in a leptin-independent manner. We found that leptin receptor-deficient rats, which develop less severe hypoxia-induced pulmonary hypertension, are protected against decreased Treg function after hypoxic exposure.CONCLUSIONS:Taken together, our results suggest that Treg dysfunction is common to all forms of PAH and may contribute to the development and the progression of the disease.

Background: Interleukin (IL)-6 has been linked to the prognosis of pulmonary arterial hypertension (PAH). However, precise contributions of IL-6 and its signaling system to PAH progression is unknown. Objectives: To study pathogenic roles of IL-6 cis- and trans-signaling in experimental and human PAH and to evaluate the translational potential of IL-6 signaling inhibition. Methods: We examined the global expression pattern of key actors of the IL-6 signaling in human lung tissues, blood samples and cultured pulmonary artery smooth muscle cells (PASMCs) of 10 controls and 10 idiopathic PAH (IPAH) patients. In addition, two complementary animal PAH models have been explored: the Sugen 5416 plus chronic hypoxia and the monocrotaline rat models. Results: In IPAH, serum levels of IL-6 and soluble IL-6 receptors (sIL-6R) proteins were higher than in control subjects. We also found stronger immunoreactivity for IL-6R, phospho-STAT3 and Mcl-1 (myeloid leukemia-cell protein 1) in PASMCs of remodeled pulmonary arteries and cultured PASMCs of IPAH patients compared with controls. These abnormalities in the IL-6/IL-6R signaling were also histologically found in the two rat models. Consistent with these findings, we also found that IL-6 with or without sIL-6R could substantially increase STAT3 phosphorylation and expression of anti-apoptotic Mcl-1 protein in cultured IPAH PASMCs compared with control PASMCs. These effects were partially abolished in the presence of IL-6R neutralizing antibodies. Conclusions: Our findings suggest that abnormalities in IL-6 signaling may contribute to the pathogenesis of PAH through modulation of PASMC survival.

Rationale: In idiopathic pulmonary arterial hypertension (iPAH), pulmonary-endothelial cells (P-ECs) display phenotypic abnormalities including a greater proliferative response to growth factors and apoptosis resistance; however, the precise underlying mechanisms remain obscure. Excessive MIF (macrophage migration-inhibitory factor) expression during the initial stages of tumor contributes to endothelial proliferation, tumor growth and progression. Objectives: We therefore hypothesized that MIF could function as a growth/survival factor promoting the altered P-EC phenotype in iPAH and disease progression. Results: In distal pulmonary arteries (PAs) of patients with iPAH, we found a strong immunoreactivity for MIF in the endothelium compared with PAs from control patients. This aberrant endothelial MIF expression is also found in the SU5416 plus hypoxia/normoxia- exposed rats and the monocrotaline-injected rats as models of human PAH. These in situ observations were replicated in vitro , with cultured P-ECs from patients with iPAH exhibiting increased MIF expression and release compared with control P-ECs. Decreasing MIF expression and signaling by RNA interference or a specific MIF inhibitor called ISO-1 decreased proliferation and induced apoptosis of iPAH P-ECs. Finally, we found that daily treatment of rats with ISO-1 for 2 weeks started 1 week after a subcutaneous monocrotaline injection partially reverses development of pulmonary hypertension. Conclusions: We report here that the pulmonary endothelium of iPAH patients represents a local abnormal source of MIF that could contribute to the hyperproliferative phenotype of iPAH endothelial cells.

Excessive proliferation of pulmonary arterial smooth muscle cells (PA-SMCs) and perivascular inflammation lead to pulmonary arterial hypertension (PAH) progression, but they are not specifically targeted by the current therapies. Since leptin (Ob) and its main receptor ObR-b contribute to systemic vascular cell proliferation and inflammation, we questioned whether targeting Ob/ObR-b axis would be an effective antiproliferative and anti-inflammatory strategy against PAH.In idiopathic PAH (iPAH), using human lung tissues and primary cell cultures (early passages ≤5), we demonstrate that pulmonary endothelial cells (P-ECs) over produce Ob and that PA-SMCs overexpress ObR-b. Furthermore, we obtain evidence that Ob enhances proliferation of human PA-SMCsin vitroand increases right ventricular systolic pressure in Ob-treated mice in the chronic hypoxia-induced pulmonary hypertension (PH) model. Using human cells, we also show that Ob leads to monocyte activation and increases cell adhesion molecule expression levels in P-ECs. We also find that Ob/ObR-b axis contributes to PH susceptibility by using ObR-deficient rats, which display less severe hypoxia-induced PH (pulmonary haemodynamics, arterial muscularisation, PA-SMC proliferation and perivascular inflammation). Importantly, we demonstrate the efficacy of two curative strategies using a soluble Ob neutraliser and dichloroacetate in hypoxia-induced PH.We demonstrate here that Ob/ObR-b axis may represent anti-proliferative and anti-inflammatory targets in PAH.