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Diffusing capacity of the lung for carbon monoxide (DLWe retrospectively analysed pre-implant and post-implant data from 42 patients implanted with a LVAD at our institution. Out of 42 patients, 35 had post-capillary PH before implantation, including 17 with combined post- and pre-capillary PH (Cpc-PH). Median DLBefore LVAD implantation, DL

Background: Right heart failure (RHF) is associated with a dismal prognosis in patients with pulmonary hypertension (PH). Exercise right heart catheterization may unmask right heart maladaptation as a sign of RHF. We sought to (1) define the normal limits of right atrial pressure (RAP) increase during exercise; (2) describe the right heart adaptation to exercise in PH owing to heart failure with preserved ejection fraction (PH-HFpEF) and in pulmonary arterial hypertension (PAH); and (3) identify the factors associated with right heart maladaptation during exercise. Methods and results: We analyzed rest and exercise right heart catheterization from patients with PH-HFpEF and PAH. Right heart adaptation was described by absolute or cardiac output (CO)-normalized changes of RAP during exercise. Individuals with noncardiac dyspnea (NCD) served to define abnormal RAP responses (>97.5th percentile). Thirty patients with PH-HFpEF, 30 patients with PAH, and 21 patients with NCD were included. PH-HFpEF were older than PAH, with more cardiovascular comorbidities, and a higher prevalence of severe tricuspid regurgitation (P < .05). The upper limit of normal for peak RAP and RAP/CO slope in NCD were >12 mmHg and ≥1.30 mmHg/L/min, respectively. PH-HFpEF had higher peak RAP and RAP/CO slope than PAH (20 mmHg [16-24 mmHg] vs 12 mmHg [9-19 mmHg] and 3.47 mmHg/L/min [2.02-6.19 mmHg/L/min] vs 1.90 mmHg/L/min [1.01-4.29 mmHg/L/min], P < .05). A higher proportion of PH-HFpEF had RAP/CO slope and peak RAP above normal (P < .001). Estimated stressed blood volume at peak exercise was higher in PH-HFpEF than PAH (P < .05). In the whole PH cohort, the RAP/CO slope was associated with age, the rate of increase in estimated stressed blood volume during exercise, severe tricuspid regurgitation, and right atrial dilation. Conclusions: Patients with PH-HFpEF display a steeper increase of RAP during exercise than those with PAH. Preload-mediated mechanisms may play a role in the development of exercise-induced RHF.

During the ESC congress in September 2020, the new ESC guidelines were presented and are available on the ESC website. The new guidelines describe management recommendations on following cardiovascular diseases: non-STE ACS, adult congenital heart disease, sports cardiology and atrial fibrillation. The present document gives a summary of these guidelines and highlights the most important recommendations and changes in the management of these diseases. It will help to increase awareness about the new guidelines and may stimulate to consult the full document for specific items. Ultimately, the authors hope that this document will enhance implementation of new ESC guidelines in daily clinical practice.

Aims Exercise right heart catheterization (RHC) is considered the gold-standard test to diagnose heart failure with preserved ejection fraction (HFpEF). However, exercise RHC is an insufficiently standardized technique, and current haemodynamic thresholds to define HFpEF are not universally accepted. We sought to describe the exercise haemodynamics profile of HFpEF cohorts reported in literature, as compared with control subjects. Methods and results We performed a systematic literature review until December 2020. Studies reporting pulmonary artery wedge pressure (PAWP) at rest and peak exercise were extracted. Summary estimates of all haemodynamic variables were evaluated, stratified according to body position (supine/upright exercise), and the PAWP/cardiac output (CO) slope during exercise was extrapolated. Twenty-eight studies were identified, providing data for 2230 HFpEF patients and 706 controls. At peak exercise, patients with HFpEF achieved higher PAWP [30 (29–31) vs. 16 (15–17) mmHg, P Conclusions The haemodynamic profile of HFpEF patients is consistent across studies and characterized by a higher left and right filling pressure at rest, magnified by physical exercise. Our analysis strongly suggests that PAWP/CO slope might allow for a more consistent identification of HFpEF, irrespective of body position. This variable likely overcomes the shortcomings of an isolated peak PAWP measurement, allowing for a more univocal identification of HFpEF in patients with unexplained dyspnoea.

BACKGROUND There were gaps between guidelines and practice when surgery was the only treatment for aortic stenosis (AS). OBJECTIVES This study analyzed the decision to intervene in patients with severe AS in the EORP VHD (EURObservational Research Programme Valvular Heart Disease) II survey. METHODS Among 2,152 patients with severe AS, 1,271 patients with high-gradient AS who were symptomatic fulfilled a Class I recommendation for intervention according to the 2012 European Society of Cardiology guidelines; the primary end point was the decision for intervention. RESULTS A decision not to intervene was taken in 262 patients (20.6%). In multivariate analysis, the decision not to intervene was associated with older age (odds ratio [OR]: 1.34 per 10-year increase; 95% CI: 1.11 to 1.61; P = 0.002), New York Heart Association functional classes I and II versus III (OR: 1.63; 95% CI: 1.16 to 2.30; P = 0.005), higher age adjusted Charlson comorbidity index (OR: 1.09 per 1-point increase; 95% CI: 1.01 to 1.17; P = 0.03), and a lower transaortic mean gradient (OR: 0.81 per 10-mm Hg decrease; 95% CI: 0.71 to 0.92; P < 0.001). During the study period, 346 patients (40.2%, median age 84 years, median EuroSCORE II [European System for Cardiac Operative Risk Evaluation II] 3.1%) underwent transcatheter intervention and 515 (59.8%, median age 69 years, median EuroSCORE II 1.5%) underwent surgery. A decision not to intervene versus intervention was associated with lower 6-month survival (87.4%; 95% CI: 82.0 to 91.3 vs 94.6%; 95% CI: 92.8 to 95.9; P < 0.001). CONCLUSIONS A decision not to intervene was taken in 1 in 5 patients with severe symptomatic AS despite a Class I recommendation for intervention and the decision was particularly associated with older age and combined comorbidities. Transcatheter intervention was extensively used in octogenarians. (J Am Coll Cardiol 2021;78:2131-2143) (c) 2021 by the American College of Cardiology Foundation.

Thanks to a better knowledge of the genetic causes of many diseases and an improvement in genetic testing techniques, genetics has gained an important role in the multidisciplinary approach to diagnosis and management of congenital heart disease and aortic pathology. With the introduction of strategies for precision medicine, it is expected that this will only increase further in the future. Because basic knowledge of the indications, the opportunities as well as the limitations of genetic testing is essential for correct application in clinical practice, this consensus document aims to give guidance to care-providers involved in the follow-up of adults with congenital heart defects and/or with hereditary aortic disease. This paper is the result of a collaboration between the ESC Working Group of Grown-Up Congenital Heart Disease, the ESC Working Group on Aorta and Peripheral Vascular Disease and the European Society of Human Genetics. Throughout the document, the importance of correct counseling in the process of genetic testing is emphasized, indications and timing for genetic studies are discussed as well as the technical modalities of genetic testing. Finally, the most important genetic diseases in adult congenital heart disease and aortic pathology are also discussed., SCOPUS: ar.j, info:eu-repo/semantics/published

Eosinophil-mediated endomyocardial damage is a well-known complication in patients with hypereosinophilic syndromes (HES). Although management and survival have improved significantly, some patients continue to develop severe cardiomyopathy as a direct consequence of uncontrolled hypereosinophilia. Cardiologists play a key role in early detection and treatment. At the early generally asymptomatic stage, related to subendocardial eosinophilic infiltrates, elevation of the biomarker of cardiac damage (serum troponin) and cardiac MRI are the best tools for diagnosis. As disease progresses, patients typically develop intracardiac mural thrombi and may experience variable degrees of heart failure due to valve damage and/or subendocardial fibrosis, all of which are more readily detectable with traditional echocardiographic investigation. New imaging modalities such as strain imaging and specific sequences in MRI offer the perspective of detecting subtle perturbations and distinguishing inflammatory versus fibrotic stages. Endomyocardial biopsy may help in difficult settings, namely, when blood eosinophilia is not prominent, but may be non-contributive due to sampling issues or eosinophil degranulation or replacement by fibrosis, and must always be performed after careful consideration of the risk:benefit ratio. Although treatment of the HES itself should be managed by clinicians with expertise in this rare disorder with the aim of lowering eosinophil counts to prevent and treat eosinophil-mediated organ damage and dysfunction, cardiologists play a key role in managing the associated cardiopathy. There are no consensual disease-specific guidelines for treating eosinophil-mediated thrombotic complications and cardiopathy, which should be managed according to classical international recommendations.

Background: Cardiac muscle hypercontractility is a key pathophysiological abnormality in hypertrophic cardiomyopathy, and a major determinant of dynamic left ventricular outflow tract (LVOT) obstruction. Available pharmacological options for hypertrophic cardiomyopathy are inadequate or poorly tolerated and are not disease-specific. We aimed to assess the efficacy and safety of mavacamten, a first-in-class cardiac myosin inhibitor, in symptomatic obstructive hypertrophic cardiomyopathy. Methods: In this phase 3, randomised, double-blind, placebo-controlled trial (EXPLORER-HCM) in 68 clinical cardiovascular centres in 13 countries, patients with hypertrophic cardiomyopathy with an LVOT gradient of 50 mm Hg or greater and New York Heart Association (NYHA) class II–III symptoms were assigned (1:1) to receive mavacamten (starting at 5 mg) or placebo for 30 weeks. Visits for assessment of patient status occurred every 2–4 weeks. Serial evaluations included echocardiogram, electrocardiogram, and blood collection for laboratory tests and mavacamten plasma concentration. The primary endpoint was a 1·5 mL/kg per min or greater increase in peak oxygen consumption (pVO2) and at least one NYHA class reduction or a 3·0 mL/kg per min or greater pVO2 increase without NYHA class worsening. Secondary endpoints assessed changes in post-exercise LVOT gradient, pVO2, NYHA class, Kansas City Cardiomyopathy Questionnaire-Clinical Summary Score (KCCQ-CSS), and Hypertrophic Cardiomyopathy Symptom Questionnaire Shortness-of-Breath subscore (HCMSQ-SoB). This study is registered with ClinicalTrials.gov, NCT03470545. Findings: Between May 30, 2018, and July 12, 2019, 429 adults were assessed for eligibility, of whom 251 (59%) were enrolled and randomly assigned to mavacamten (n=123 [49%]) or placebo (n=128 [51%]). 45 (37%) of 123 patients on mavacamten versus 22 (17%) of 128 on placebo met the primary endpoint (difference +19·4%, 95% CI 8·7 to 30·1; p=0·0005). Patients on mavacamten had greater reductions than those on placebo in post-exercise LVOT gradient (−36 mm Hg, 95% CI −43·2 to −28·1; p2 (+1·4 mL/kg per min, 0·6 to 2·1; p=0·0006), and improved symptom scores (KCCQ-CSS +9·1, 5·5 to 12·7; HCMSQ-SoB −1·8, −2·4 to −1·2; p

Background: Familial hypercholesterolaemia (FH) is underdiagnosed in most countries. We report our first experience from a national pilot project of cascade screening in relatives of FH patients. Methodology: Participating specialists recruited consecutive index patients (IP) with Dutch Lipid Clinic Network (DLCN) score ≥6. After informed consent, the relatives were visited by the nurses to collect relevant clinical data and perform blood sampling for lipid profile measurement. FH diagnosis in the relatives was based on the DLCN and/or MEDPED FH (Make-Early-Diagnosis-to-Prevent-Early-Deaths-in-FH) criteria. Results: In a period of 18 months, a total of 127 IP (90 with definite FH and 37 with probable FH) were enrolled in 15 centres. Out of the 270 relatives visited by the nurses, 105 were suspected of having FH: 31 with DCLN score >8, 33 with DLCN score 5-8 and 41 with MEDPED FH criteria. In a post-hoc analysis, another set of MEDPED FH criteria established in the Netherlands and adapted to Belgium allowed to detect FH in 51 additional relatives. Conclusion: In a country with no national FH screening program, our pilot project demonstrated that implementing a simple phenotypical FH cascade screening strategy using the collaboration of motivated specialists and two nurses, allowed to diagnose FH in 127 index patients and an additional 105 of their relatives over the two-year period. Newly developed MEDPED FH cut-offs, easily applicable by a nurse with a single blood sample, might further improve the sensitivity of detecting FH within families., SCOPUS: ar.j, info:eu-repo/semantics/published

Introduction Interstitial lung disease and pulmonary hypertension are the leading causes of morbidity and mortality in patients with systemic sclerosis (SSc). Exercise-induced dyspnea is the first manifestation of both complications, which explains why the value of resting tests to predict preclinical heart or lung involvement is limited. Cardiopulmonary exercise testing (CPET) offers a comprehensive approach to identify the cause of exercise limitation. However, the role of CPET in SSc patients without demonstrated cardiac and/or respiratory disease has not been extensively investigated. Purpose We sought to compare the cardiopulmonary adaptation to exercise of SSc patients without cardiac or pulmonary disease vs. healthy controls. Methods SSc patients with normal resting echocardiography and pulmonary functional test, and healthy volunteers were prospectively enrolled. All underwent maximal CPET and results were compared after correction for age and gender. Results Thirty-nine patients (females 36, age 54 ± 12) and 43 healthy subjects (females 31, age 46 ± 11) were included between 07/2015 and 05/2018. Exercise capacity was lower in patients than in healthy subjects ( Table 1 ). Patients had lower oxygen uptake (VO2) at peak exercise and higher minute ventilation/carbon dioxide production (VE/VCO2) slope than controls ( Fig. 1 ). They had higher VE/VCO2 ratio and lower end-tidal pressure of CO2 (PetCO2) at the ventilatory threshold. Ventilatory reserve was preserved and peripheral oxygen saturation was normal in both groups. Conclusion The combination of low peak VO2, high VE/VCO2 slope, low PetCO2, and high respiratory reserve suggest that patients with SSc without overt cardiac or respiratory disease present with a cardiovascular limitation to exercise. The latter may be related to latent cardiac dysfunction or pulmonary vascular disease.

Purpose DLCO reduction is commonly observed in HF and is associated with a worse outcome. Correlations between DLCO and PH are unclear and published data are conflicting; moreover, it has been shown that even after normalization of pulmonary pressures driven by the LVAD, a DLCO impairment may persist or worsen, maybe reflecting the persistence of pulmonary vascular remodeling. In this study we investigated correlations between pre-implant DLCO, hemodynamics and post-implant outcome in patients with advanced HF implanted with a LVAD. Methods We retrospectively analyzed pre-implant clinical data and post-implant outcome of 42 patients implanted with a LVAD at our institution in whom a DLCO measurement was performed before surgery. Results Out of 42 patients (71% males, mean age 53 y), 35 (83%) had post-capillary PH, including 17 (40%) with combined post and pre-capillary PH (CpcPH; defined in1). At baseline, median DLCO was 59% (range 21-100%) and it inversely correlated with PVR (p 0.037) and DPG (p 0.042).Early after surgery, more than mild right HF (RHF) occurred in 12 patients, 4 of which died; neither RHF severity nor intensive care unit length of stay were associated with DLCO. Compared to baseline, the LVAD resulted in a significant reduction in LV dimension (Dd 61 vs 69 mm, p Conclusion We showed a significant improvement in hemodynamics after LVAD implantation. Reduced DLCO is associated with CpcPH suggesting that impaired DLCO may be a marker of pulmonary vascular remodeling. 1Galie N et al Eur Heart J 2015; doi:10.1093/eurheartj/ehv317

Purpose Pulmonary hypertension (PH) in left heart diseases (LHD) has been redefined as isolated post-capillary PH (IpcPH) and combined post-capillary and pre-capillary PH (CpcPH). CpcPH's pathophysiology is not well understood. Predisposing constitutional factors may play a role in CpcPH development, as suggested by the variability in the adaptation of the pulmonary circulation to the elevation of pulmonary artery wedge pressure (PAWP). We sought to determine whether a genetic predisposition to CpcPH could be identified, suggesting a common pathway with pulmonary arterial hypertension (PAH). Methods Based on Erasme's hospital right heart catheterization database from January 2007 to January 2015, we selected PH-LHD patients to further identify CpcPH patients. Clinical and hemodynamic variables were used to compare IpcPH to CpcPH patients. A small cohort of CpcPH patients underwent genetic testing for genes predisposing to heritable PAH using a gene panel approach and MLPA analysis. Results 93 patients presented with PH-LHD, of which 32% met the definition of CpcPH. Clinical data was similar in both IpcPH and CpcPH groups except for higher morphometric features in CpcPH patients. Missense variations of the BMPR2 gene (c.1749C>A, p.Asn583Lys) and of the ENG gene (c.1316A>C, p.Lys439Thr) were identified in one CpcPH patient presenting with heart failure due to dilated cardiomyopathy. Based on current knowledge, both variants were classified as variants of unknown significance (VUS). Conclusion Our study uncovered genomic variations in the BMPR2 and ENG genes of a CpcPH patient, which may support the concept that a predisposing genetic background could modulate the precapillary component in CpcPH, potentially suggesting common genetic pathways between CpcPH and PAH, although this has to be further confirmed by functional testing, studies in bigger cohorts and with IpcPH control populations.

Introduction Systemic sclerosis (SSc) is a severe form of associated pulmonary arterial hypertension (PAH), for which annual screening is recommended based on resting echocardiography. While the latter may be normal in the early stages of PAH, exercise echocardiography (Ex-Echo) may provide additional insights on pulmonary vascular function. However, the clinical use of Ex-Echo is limited by methodological concerns. Although it is currently admitted that pulmonary arterial pressure (PAP) at exercise should be interpreted relative to flow change, few studies investigated the relationship between PAP and cardiac output (CO) during exercise in SSc patients. Purpose We sought to explore exercise-induced changes in the pulmonary circulation by pressure-flow relationship in SSc patients compared with healthy subjects. Methods SSc patients without overt lung or heart involvement, and healthy subjects underwent symptom-limited Ex-Echo to generate multipoint relationship between meanPAP (PAPm) and CO. Conventional markers of RV function were also recorded during exercise. Results Forty-two patients and 47 controls were included. At peak exercise, patients had lower PAP, lower CO, but higher PAPm to CO ratio (TPR) than controls ( Table 1 ). The slope of PAPm to CO relationship (P/Q slope) was higher in patients ( Fig. 1 ), but this was not significant after correction for age. Age was an independent determinant for the P/Q slope, but did not affect the difference in peak-exercise TPR. Markers of RV function (TAPSE, S wave velocity, and IVA) were lower in patients at exercise. Conclusion SSc patients presented with different pulmonary vascular and myocardial adaptation to exercise compared with healthy individuals. In contrast with P/Q slope, changes in peak TPR were not influenced by age. This pattern may be observed in patients without evidence of cardiac or pulmonary involvement and explain, at least in part, lower exercise capacity in these patients.

Background and aims: Familial hypercholesterolaemia (FH) is an autosomal dominant lipoprotein disorder characterized by significant elevation of low-density lipoprotein cholesterol (LDL-C) and markedly increased risk of premature cardiovascular disease (CVD). Because of the very high coronary artery disease risk associated with this condition, the prevalence of FH among patients admitted for CVD outmatches many times the prevalence in the general population. Awareness of this disease is crucial for recognizing FH in the aftermath of a hospitalization of a patient with CVD, and also represents a unique opportunity to identify relatives of the index patient, who are unaware they have FH. This article aims to describe a feasible strategy to facilitate the detection and management of FH among patients hospitalized for CVD. Methods: A multidisciplinary national panel of lipidologists, cardiologists, endocrinologists and cardio-geneticists developed a three-step diagnostic algorithm, each step including three key aspects of diagnosis, treatment and family care. Results: A sequence of tasks was generated, starting with the process of suspecting FH amongst affected patients admitted for CVD, treating them to LDL-C target, finally culminating in extensive cascade-screening for FH in their family. Conceptually, the pathway is broken down into 3 phases to provide the treating physicians with a time-efficient chain of priorities. Conclusions: We emphasize the need for optimal collaboration between the various actors, starting with a “vigilant doctor” who actively develops the capability or framework to recognize potential FH patients, continuing with an “FH specialist” and finally involving the patient himself as ”FH ambassador” to approach his/her family and facilitate cascade screening and subsequent treatment of relatives., SCOPUS: ar.j, info:eu-repo/semantics/published

Dilated cardiomyopathy (DCM) frequently affects relatively young, economically, and socially active adults, and is an important cause of heart failure and transplantation. DCM is a complex disease and its pathological architecture encounters many genetic determinants interacting with environmental factors. The old perspective that every pathogenic gene mutation would lead to a diseased heart, is now being replaced by the novel observation that the phenotype depends not only on the penetrance—malignancy of the mutated gene—but also on epigenetics, age, toxic factors, pregnancy, and a diversity of acquired diseases. This review discusses how gene mutations will result in mutation-specific molecular alterations in the heart including increased mitochondrial oxidation (sarcomeric gene e.g. TTN), decreased calcium sensitivity (sarcomeric genes), fibrosis (e.g. LMNA and TTN), or inflammation. Therefore, getting a complete picture of the DCM patient will include genomic data, molecular assessment by preference from cardiac samples, stratification according to co-morbidities, and phenotypic description. Those data will help to better guide the heart failure and anti-arrhythmic treatment, predict response to therapy, develop novel siRNA-based gene silencing for malignant gene mutations, or intervene with mutation-specific altered gene pathways in the heart. This article is part of the Mini Review Series from the Varenna 2017 meeting of the Working Group of Myocardial Function of the European Society of Cardiology.

Background: In pulmonary hypertension (PH), both wedge pressure elevation and a precapillary component may affect right ventricular (RV) afterload. These changes may contribute to RV failure and prognosis. Aim: To characterize the impact of pulmonary haemodynamics on RV function and outcome in patients with PH. Methods: Patients with PH due to left heart disease (LHD) were compared with treatment-naive idiopathic/heritable pulmonary arterial hypertension (PAH, n=35). PH-LHD were subdivided in Isolated post-capillary PH (IpcPH: diastolic pressure gradient, DPG 3, n=27), and “indeterminate” PH (DPG > 7mmHg or PVR > 3WU, n=29).. Results: Despite similar PAWP and PVR, haemodynamic severity and prevalence of RV failure increased from IpcPH, to “indeterminate” and CpcPH. PVR and DPG (but not compliance, Ca) were linearly correlated with RV failure (figure). CpcPH had worse prognosis (p Conclusions: Haemodynamic characterization of PH-LHD is associated with disease severity, predisposition to RV failure and prognosis. Ca and NTproBNP were independent predictors of survival.

SCOPUS: le.j, info:eu-repo/semantics/published

Although it is well recognized that haematopoietic stem cells (HSCs) develop from a specialized population of endothelial cells known as haemogenic endothelium, the regulatory pathways that control this transition are not well defined. Here we identify Sox17 as a key regulator of haemogenic endothelial development. Analysis of Sox17-GFP reporter mice revealed that Sox17 is expressed in haemogenic endothelium and emerging HSCs and that it is required for HSC development. Using the mouse embryonic stem cell differentiation model, we show that Sox17 is also expressed in haemogenic endothelium generated in vitro and that it plays a pivotal role in the development and/or expansion of haemogenic endothelium through the Notch signalling pathway. Taken together, these findings position Sox17 as a key regulator of haemogenic endothelial and haematopoietic development.

Background Excessive exercise-induced hyperventilation and high prevalence of exercise oscillatory breathing (EOB) are present in patients with post-capillary pulmonary hypertension (PH) complicating left heart disease (LHD). Patients with pre-capillary PH have even higher hyperventilation but no EOB. We sought to determine the impact of a pre-capillary component of PH on ventilatory response to exercise in patients with PH and left heart disease. Methods We retrospectively compared patients with idiopathic or heritable pulmonary arterial hypertension (PAH, n = 29), isolated post-capillary PH (IpcPH, n = 29), and combined post- and pre-capillary PH (CpcPH, n = 12). Diastolic pressure gradient (DPG = diastolic pulmonary artery pressure − pulmonary wedge pressure) was used to distinguish IpcPH (DPG 3 Wood unit. Exercise-induced hyperventilation (high minute ventilation over carbon dioxide production, low end-tidal carbon dioxide) was marked in PAH, intermediate in CpcPH, and low in IpcPH (p < 0.001) and correlated with DPG and PVR. Prevalence of EOB decreased from IpcPH to CpcPH to PAH (p < 0.001). Conclusions Patients with CpcPH may have worse hemodynamics than patients with IpcPH and distinct alterations of ventilatory control, consistent with more exercise-induced hyperventilation and less EOB. This might be explained at least in part by the presence and extent of pulmonary vascular disease

During embryonic development and embryonic stem cell (ESC) differentiation, the different cell lineages of the mature heart arise from two types of multipotent cardiovascular progenitors (MCPs), the first and second heart fields. A key question is whether these two MCP populations arise from differentiation of a common progenitor. In this paper, we engineered Mesp1-green fluorescent protein (GFP) ESCs to isolate early MCPs during ESC differentiation. Mesp1-GFP cells are strongly enriched for MCPs, presenting the ability to differentiate into multiple cardiovascular lineages from both heart fields in vitro and in vivo. Transcriptional profiling of Mesp1-GFP cells uncovered cell surface markers expressed by MCPs allowing their prospective isolation. Mesp1 is required for MCP specification and the expression of key cardiovascular transcription factors. Isl1 is expressed in a subset of early Mesp1-expressing cells independently of Mesp1 and acts together with Mesp1 to promote cardiovascular differentiation. Our study identifies the early MCPs residing at the top of the cellular hierarchy of cardiovascular lineages during ESC differentiation., Journal Article, Research Support, Non-U.S. Gov't, SCOPUS: ar.j, info:eu-repo/semantics/published

In pulmonary hypertension (PH), both wedge pressure elevation (PAWP) and a precapillary component may affect right ventricular (RV) afterload. These changes may contribute to RV failure and prognosis. We aimed at describing the different haemodynamic phenotypes of patients with PH due to left heart disease (LHD) and at characterizing the impact of pulmonary haemodynamics on RV function and outcome PH-LHD., SCOPUS: ar.j, info:eu-repo/semantics/published

SummaryDuring embryonic development, multipotent cardiovascular progenitor cells are specified from early mesoderm. Using mouse ESCs in which gene expression can be temporally regulated, we have found that transient expression of Mesp1 dramatically accelerates and enhances multipotent cardiovascular progenitor specification through an intrinsic and cell autonomous mechanism. Genome-wide transcriptional analysis indicates that Mesp1 rapidly activates and represses a discrete set of genes, and chromatin immunoprecipitation shows that Mesp1 directly binds to regulatory DNA sequences located in the promoter of many key genes in the core cardiac transcriptional machinery, resulting in their rapid upregulation. Mesp1 also directly represses the expression of key genes regulating other early mesoderm and endoderm cell fates. Our results demonstrate that Mesp1 acts as a key regulatory switch during cardiovascular specification, residing at the top of the hierarchy of the gene network responsible for cardiovascular cell-fate determination.

We take a functional genomics approach to congenital heart disease mechanism. We used DamID to establish a robust set of target genes for NKX2-5 wild type and disease associated NKX2-5 mutations to model loss-of-function in gene regulatory networks. NKX2-5 mutants, including those with a crippled homeodomain, bound hundreds of targets including NKX2-5 wild type targets and a unique set of "off-targets", and retained partial functionality. NKXΔHD, which lacks the homeodomain completely, could heterodimerize with NKX2-5 wild type and its cofactors, including E26 transformation-specific (ETS) family members, through a tyrosine-rich homophilic interaction domain (YRD). Off-targets of NKX2-5 mutants, but not those of an NKX2-5 YRD mutant, showed overrepresentation of ETS binding sites and were occupied by ETS proteins, as determined by DamID. Analysis of kernel transcription factor and ETS targets show that ETS proteins are highly embedded within the cardiac gene regulatory network. Our study reveals binding and activities of NKX2-5 mutations on WT target and off-targets, guided by interactions with their normal cardiac and general cofactors, and suggest a novel type of gain-of-function in congenital heart disease.

During embryonic development, Mesp1 marks the earliest cardiovascular progenitors (CPs) and promotes their specification, epithelial-mesenchymal transition (EMT), and cardiovascular differentiation. However, Mesp1 deletion in mice does not impair initial CP specification and early cardiac differentiation but induces cardiac malformations thought to arise from a defect of CP migration. Using inducible gain-of-function experiments during embryonic stem cell differentiation, we found that Mesp2, its closest homolog, was as efficient as Mesp1 at promoting CP specification, EMT, and cardiovascular differentiation. However, only Mesp1 stimulated polarity and directional cell migration through a cellautonomous mechanism. Transcriptional analysis and chromatin immunoprecipitation experiments revealed that Mesp1 and Mesp2 activate common target genes that promote CP specification and differentiation. We identified two direct Mesp1 target genes, Prickle1 and RasGRP3, that are strongly induced by Mesp1 and not by Mesp2 and that control the polarity and the speed of cell migration. Altogether, our results identify the molecular interface controlled by Mesp1 that links CP specification and cell migration., SCOPUS: ar.j, info:eu-repo/semantics/published

CCR5 is a functional receptor for various inflammatory CC-chemokines, including macrophage inflammatory protein (MIP)-1alpha and RANTES (regulated on activation normal T cell expressed and secreted), and is the main coreceptor of human immunodeficiency viruses. The second extracellular loop and amino-terminal domain of CCR5 are critical for chemokine binding, whereas the transmembrane helix bundle is involved in receptor activation. Chemokine domains and residues important for CCR5 binding and/or activation have also been identified. However, the precise way by which chemokines interact with and activate CCR5 is presently unknown. In this study, we have compared the binding and functional properties of chemokine variants onto wild-type CCR5 and CCR5 point mutants. Several mutations in CCR5 extracellular domains (E172A, R168A, K191A, and D276A) strongly affected MIP-1alpha binding but had little effect on RANTES binding. However, a MIP/RANTES chimera, containing the MIP-1alpha N terminus and the RANTES core, bound to these mutants with an affinity similar to that of RANTES. Several CCR5 mutants affecting transmembrane helices 2 and 3 (L104F, L104F/F109H/F112Y, F85L/L104F) reduced the potency of MIP-1alpha by 10-100 fold with little effect on activation by RANTES. However, the MIP/RANTES chimera activated these mutants with a potency similar to that of MIP-1alpha. In contrast, LD78beta, a natural MIP-1alpha variant, which, like RANTES, contains a proline at position 2, activated these mutants as well as RANTES. Altogether, these results suggest that the core domains of MIP-1alpha and RANTES bind distinct residues in CCR5 extracellular domains, whereas the N terminus of chemokines mediates receptor activation by interacting with the transmembrane helix bundle.

MIP-1beta is a CC-chemokine that plays a role in inflammation and host defense mechanisms by interacting with its specific receptor CCR5. CCR5 is a major coreceptor for macrophage-tropic human immunodeficiency virus (HIV), and as a consequence, MIP-1beta can inhibit HIV entry. It is therefore of interest to understand how MIP-1beta and other CCR5 ligands bind to their receptor, as such understanding could lead to the rational design of more efficient HIV entry blockers. We have previously demonstrated the importance of Phe13, and of basic residues of the 40's loop, in mediating high-affinity binding of MIP-1beta to CCR5. We have now investigated further the relative contribution of other MIP-1beta residues in the interaction of the chemokine with CCR5, by studying the functional consequences of point mutations within the N-loop and the 3(10) turn of MIP-1beta, affecting the charge, size, and H-bonding properties of the side chains. Our data suggest that, in addition to Phe13, three amino acids of the N-loop and 3(10) turn (Arg18, Lys19, and Arg22) interact with CCR5 through their positive charge. We also found that Pro21 contributes to the CCR5 binding properties of MIP-1beta. Moreover, NMR spectroscopy has revealed that the presence of Tyr at position 15 is necessary for the proper folding of the chemokine. Our results therefore demonstrate that the binding determinants of MIP-1beta consist of residues arranged on one surface of the protein, including most of the basic residues in MIP-1beta, as well as two key hydrophobic groups. The good correlation observed between the potency of the mutants in a functional assay and their binding affinity strongly argues that basic residues Arg18, Lys19, and Arg22 of MIP-1beta are essential for its CCR5 binding properties, without a primary effect on CCR5 activation.

Cardiac development arises from two sources of mesoderm progenitors, the first heart field (FHF) and the second (SHF). Mesp1 has been proposed to mark the most primitive multipotent cardiac progenitors common for both heart fields. Here, using clonal analysis of the earliest prospective cardiovascular progenitors in a temporally controlled manner during early gastrulation, we found that Mesp1 progenitors consist of two temporally distinct pools of progenitors restricted to either the FHF or the SHF. FHF progenitors were unipotent, whereas SHF progenitors were either unipotent or bipotent. Microarray and single-cell PCR with reverse transcription analysis of Mesp1 progenitors revealed the existence of molecularly distinct populations of Mesp1 progenitors, consistent with their lineage and regional contribution. Together, these results provide evidence that heart development arises from distinct populations of unipotent and bipotent cardiac progenitors that independently express Mesp1 at different time points during their specification, revealing that the regional segregation and lineage restriction of cardiac progenitors occur very early during gastrulation.

Vasoactive Intestinal Polypeptide (VIP) interacts with a high affinity to two subclasses of G protein coupled receptors named VPAC(1) and VPAC(2), and has a 3 - 10 fold preference for VPAC(1) over VPAC(2) receptors. Selective ligands for each receptor subclass were recently described. [R(16)]-PACAP (1 - 23) and [L(22)]-VIP are two selective VPAC(1) agonists. Chimaeric human VPAC(2)-VPAC(1) recombinant receptors expressed in CHO cells were used to identify the receptor domains implicated in these two selective ligands recognition. The VPAC(2) preference for [R(16)]-PACAP (1 - 27) over [R(16)]-PACAP (1 - 23) did not require the receptor's NH(2)-terminus domain but involved the whole transmembrane domain. In contrast, the selectivity of [L(22)]-VIP depended only on the presence of the NH(2) terminus and EC(2) domains of the VPAC(1) receptor. The present data support the idea that in the GPCR-B family of receptors the different selective ligands require different domains for their selectivity, and that the peptides carboxyl terminal sequence (amino acids 24 - 27) folds back on the transmembrane receptor domain, close to the peptides, aminoterminus.

FLWIN, info:eu-repo/semantics/published

In mammals, the heart arises from the differentiation of 2 sources of multipotent cardiovascular progenitors (MCPs). Different studies indicated that an evolutionary conserved transcriptional regulatory network controls cardiovascular development from flies to humans. Whereas in Drosophila , Tinman acts as a master regulator of cardiac development, the identification of such a master regulator in mammals remained elusive for a long time. In this review, we discuss the recent findings suggesting that Mesp1 acts as a key regulator of cardiovascular progenitors in vertebrates. Lineage tracing in mice demonstrated that Mesp1 represents the earliest marker of cardiovascular progenitors, tracing almost all the cells of the heart including derivatives of the primary and second heart fields. The inactivation of Mesp1/2 indicated that Mesp genes are essential for early cardiac mesoderm formation and MCP migration. Several recent studies have demonstrated that Mesp1 massively promotes cardiovascular differentiation during embryonic development and pluripotent stem cell differentiation and indicated that Mesp1 resides at the top of the cellular and transcriptional hierarchy that orchestrates MCP specification. In primitive chordates, Mesp also controls early cardiac progenitor specification and migration, suggesting that Mesp arises during chordate evolution to regulate the earliest step of cardiovascular development. Defining how Mesp1 regulates the earliest step of MCP specification and controls their migration is essential to understand the root of cardiovascular development and how the deregulation of these processes can lead to congenital heart diseases. In addition, these findings will be very useful to boost the production of cardiovascular cells for cellular therapy, drug and toxicity screening.

CCR5 is a G protein-coupled receptor responding to four natural agonists, the chemokines RANTES (regulated on activation normal T cell expressed and secreted), macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, and monocyte chemotactic protein (MCP)-2, and is the main co-receptor for the macrophage-tropic human immunodeficiency virus strains. We have previously identified a structural motif in the second transmembrane helix of CCR5, which plays a crucial role in the mechanism of receptor activation. We now report the specific role of aromatic residues in helices 2 and 3 of CCR5 in this mechanism. Using site-directed mutagenesis and molecular modeling in a combined approach, we demonstrate that a cluster of aromatic residues at the extracellular border of these two helices are involved in chemokine-induced activation. These aromatic residues are involved in interhelical interactions that are key for the conformation of the helices and govern the functional response to chemokines in a ligand-specific manner. We therefore suggest that transmembrane helices 2 and 3 contain important structural elements for the activation mechanism of chemokine receptors, and possibly other related receptors as well.