Publications by authors named "Martin Moser"

97 Publications

A DARPin targeting activated Mac-1 is a novel diagnostic tool and potential anti-inflammatory agent in myocarditis, sepsis and myocardial infarction.

Basic Res Cardiol 2021 Mar 15;116(1):17. Epub 2021 Mar 15.

Cardiology and Angiology I, Heart Center Freiburg University, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

The monocyte β-integrin Mac-1 is crucial for leukocyte-endothelium interaction, rendering it an attractive therapeutic target for acute and chronic inflammation. Using phage display, a Designed-Ankyrin-Repeat-Protein (DARPin) was selected as a novel binding protein targeting and blocking the α I-domain, an activation-specific epitope of Mac-1. This DARPin, named F7, specifically binds to activated Mac-1 on mouse and human monocytes as determined by flow cytometry. Homology modelling and docking studies defined distinct interaction sites which were verified by mutagenesis. Intravital microscopy showed reduced leukocyte-endothelium adhesion in mice treated with this DARPin. Using mouse models of sepsis, myocarditis and ischaemia/reperfusion injury, we demonstrate therapeutic anti-inflammatory effects. Finally, the activated Mac-1-specific DARPin is established as a tool to detect monocyte activation in patients receiving extra-corporeal membrane oxygenation, as well as suffering from sepsis and ST-elevation myocardial infarction. The activated Mac-1-specific DARPin F7 binds preferentially to activated monocytes, detects inflammation in critically ill patients, and inhibits monocyte and neutrophil function as an efficient new anti-inflammatory agent.
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http://dx.doi.org/10.1007/s00395-021-00849-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7960600PMC
March 2021

Transcatheter valve-in-valve implantation in degenerated aortic bioprostheses: are patients with small surgical bioprostheses at higher risk for unfavourable mid-term outcomes?

Ann Cardiothorac Surg 2020 Nov;9(6):478-486

Department of Cardiovascular Surgery, University Heart Center Freiburg · Bad Krozingen, Bad Krozingen, Germany.

Background: To examine outcomes of valve-in-valve (ViV) transcatheter aortic valve implantation (TAVI) according to the inner diameter (ID) of the degenerated aortic valve bioprosthesis.

Methods: We analyzed survival, stroke, permanent pacemaker (PPM) implantation, paravalvular (PV) leakage, acute kidney injury and vascular complications in fifty-nine patients during a ten-year period. Patients were stratified according to the ID of the indwelling degenerated biological aortic valve (true ID ≤ and >20 mm). Differences in post-procedural transvalvular gradients and hospital re-admissions were analyzed.

Results: The median age of the small diameter group and large diameter group was eighty-one and eighty years, respectively. Median logistic EuroSCORE I was 23.9% and 26.2% and median Society of Thoracic Surgeons (STS) score was 5.7% and 7.8% for the small and large groups, respectively. Survival, stroke, PPM implantation, PV leakage, acute kidney injury and vascular complications did not reach any statistically significant difference between both groups. Postprocedural transvalvular gradients differed significantly according to the true ID of the degenerated bioprosthetic valve and consequently of the respective TAVI valve. There was a significant difference with regard to hospital readmissions according to the true ID.

Conclusions: TAVI ViV implantation for aortic bioprostheses with small true IDs of ≤20 mm is associated with comparable mid-term mortality and periprocedural stroke rate compared to implantation into larger bioprostheses. However, the periprocedural and mid-term transvalvular gradients, as well as hospital re-admission rates are significantly higher in the small diameter group.
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http://dx.doi.org/10.21037/acs-2020-av-fs-0124DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7724066PMC
November 2020

Annexin V positive microvesicles are elevated and correlate with flow rate in patients receiving veno-arterial extracorporeal membrane oxygenation.

Interact Cardiovasc Thorac Surg 2020 Dec;31(6):884-891

Department of Cardiology and Angiology I, Heart Center Freiburg University, Medical Faculty, University of Freiburg, Freiburg, Germany.

Objectives: Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is used in critically ill patients requiring haemodynamic support. Microvesicles (MV) are released by activated blood cells acting as mediators of intercellular communication. We aimed to determine MV count and composition over time in patients with VA-ECMO and explore what drives MV formation.

Methods: VA-ECMO patients and healthy controls were recruited prospectively, and blood was taken at different time points (day 0, 1, 3 after ECMO placement and after explantation) for MV analysis.

Results: Annexin V positive MV were increased in patients (n = 14, mean age = 61.4 ± 9.0 years, 11 males, 3 females) compared to healthy controls (n = 6, Annexin V positive MV count per millilitre day 1 versus healthy controls: 2.3 × 106 vs 1.3 × 105, P < 0.001). Furthermore, patients had higher proportions of endothelial and leukocyte MV [leukocyte MV day 1 versus healthy controls (%): 32.8 vs 17.5, P = 0.001; endothelial MV day 1 versus healthy controls (%): 10.5 vs 5.5, P = 0.01]. Annexin V positive and leucocyte MV correlated with the flow rate (r = 0.46, P = 0.01).

Conclusions: Patients on VA-ECMO have increased levels of circulating MV and a changed MV composition. Our data support the hypothesis that MV release may be driven by higher flow rate and cellular activation in the extracorporeal circuit leading to poor outcomes in these patients.

Clinical Trial Registration Number: German Clinical Trials Register-ID: DRKS00011106.
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http://dx.doi.org/10.1093/icvts/ivaa198DOI Listing
December 2020

Dual-Pathway Antithrombotic Therapy in Patients With Atrial Fibrillation After Percutaneous Coronary Intervention in Stable Coronary Artery Disease: A Single-Center, Single-Operator, Retrospective Cohort Study.

Front Med (Lausanne) 2020 30;7:414. Epub 2020 Sep 30.

Department of Cardiology and Angiology I, Heart Center Freiburg University, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

There is limited data evaluating the prescription practices for antithrombotic therapy in patients with atrial fibrillation (AF) following elective percutaneous coronary intervention (PCI). This single-center, single-operator, retrospective cohort study aimed to evaluate trends of antithrombotic treatment strategies in patients with AF undergoing elective PCI. Patients with AF who electively underwent PCI performed by a single interventionalist between April 2013 and May 2018 were identified. The primary outcome was the antithrombotic therapy at discharge assessed by chart review: triple (TAT, triple antithrombotic therapy) or dual (DAT, dual antithrombotic therapy) antithrombotic therapy and vitamin K antagonist (VKA) or non-vitamin K antagonist oral anticoagulant (NOAC), respectively. Of 6,135 screened patients, 259 met the inclusion criteria. Among these, 133 (51%) patients received NOAC- and 126 (49%) VKA-therapy. Compared with patients on NOAC therapy, patients treated with VKA had higher bleeding risk (mean HAS-BLED-Score; 2.3 vs. 2.0; = 0.02) and more co-morbidities (estimated glomerular filtration rate <30 ml/min, 11 vs. 4%; = 0.04; diabetes mellitus, 33 vs. 20%; = 0.03; history of previous PCI, 37 vs. 21%; < 0.01). TAT was prescribed more frequently if the prescription included VKA compared with NOAC (61 vs. 41%; < 0.01). Prescription of TAT and VKA decreased throughout the observed period (2013: 100% vs. 2018: 6%; < 0.01 and 2013: 91% vs. 2018: 28%; < 0.01). These observational data from a single center registry show a decrease of TAT- and VKA- prescription in favor of DAT with NOAC. Whether these observations are consistent with national or global trends should to be evaluated in further studies.
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http://dx.doi.org/10.3389/fmed.2020.00414DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7561383PMC
September 2020

Endothelial BMP4 Promotes Leukocyte Rolling and Adhesion and Is Elevated in Patients After Survived Out-of-Hospital Cardiac Arrest.

Inflammation 2020 Dec;43(6):2379-2391

Department of Cardiology and Angiology I, Heart Center Freiburg University, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Leukocyte recruitment is a fundamental step in the inflammatory response during ischemia/reperfusion injury (IRI). Rolling and adhesion of leukocytes to activated endothelium promote tissue inflammation after IRI and require presentation of adhesion molecules E-selectin and ICAM-1 on the endothelial surface. Bone morphogenetic protein (BMP) 4 is a prominent member of the BMP family expressed and secreted by endothelial cells. BMP4 derived from endothelial cells has important functions in vascular disease but its influence on the leukocyte adhesion cascade during inflammation is incompletely understood. In the present study, we challenged mice with an inducible endothelial-specific BMP4 deletion (referred to as EC-BMP4 mice) and their control littermates (EC-BMP4) with thioglycollate i.p. and assessed extravasation of different leukocyte subsets during peritonitis. Peritoneal lavages were performed and peritoneal cells were counted. Total cell count in lavages of EC-BMP4 mice was markedly reduced compared with lavages of EC-BMP4 mice. FACS analyses of thioglycollate-elicited peritoneal cells revealed that diverse leukocyte subsets were reduced in EC-BMP4 mice. Intravital microscopy of cremaster venules demonstrated that rolling and adhesion of leukocytes were significantly diminished in EC-BMP4 mice in comparison with control mice in response to TNFα. These observations indicate that endothelial BMP4 is essential for rolling, adhesion, and extravasation of leukocytes in vivo. To understand the underlying mechanisms, levels of endothelial adhesion molecules E-selectin and ICAM-1 were quantified in EC-BMP4 and EC-BMP4 mice by quantitative PCR and Western blotting. Interestingly, ICAM-1 and E-selectin expressions were reduced in the hearts of EC-BMP4 mice. Next we confirmed pro-inflammatory properties of BMP4 in a gain of function experiments and found that administration of recombinant BMP4 in male C57BL/6 mice increased leukocyte rolling and adhesion in cremaster venules in vivo. To assess the regulation of BMP4 in inflammatory disease in humans, we collected plasma samples of patients from day 0 to day 7 after survived out-of-hospital cardiac arrest (OHCA, n = 42). Remarkably, plasma of OHCA patients contained significantly higher BMP4 protein levels compared with patients with coronary artery disease (CAD, n = 12) or healthy volunteers (n = 11). Subgroup analysis revealed that elevated plasma BMP4 levels after ROSC are associated with decreased survival and unfavorable neurological outcome. Collectively, endothelial BMP4 is a potent activator of inflammation in vivo that promotes rolling, adhesion, and extravasation of leukocyte subsets by induction of E-selectin and ICAM-1. Elevation of plasma BMP4 levels in the post-resuscitation period suggests that BMP4 contributes to pathophysiology and poor outcome of post-cardiac arrest syndrome.
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http://dx.doi.org/10.1007/s10753-020-01307-9DOI Listing
December 2020

Cardiomyocyte microvesicles: proinflammatory mediators after myocardial ischemia?

J Thromb Thrombolysis 2020 Oct;50(3):533-542

Cardiology and Angiology I, Heart Center Freiburg University, Medical Faculty, University of Freiburg, 79106, Freiburg im Breisgau, Germany.

Myocardial infarction is a frequent complication of cardiovascular disease leading to high morbidity and mortality worldwide. Elevated C-reactive protein (CRP) levels after myocardial infarction are associated with heart failure and poor prognosis. Cardiomyocyte microvesicles (CMV) are released during hypoxic conditions and can act as mediators of intercellular communication. MicroRNA (miRNA) are short non-coding RNA which can alter cellular mRNA-translation. Microvesicles (MV) have been shown to contain distinct patterns of miRNA from their parent cells which can affect protein expression in target cells. We hypothesized that miRNA containing CMV mediate hepatic CRP expression after cardiomyocyte hypoxia. H9c2-cells were cultured and murine cardiomyocytes were isolated from whole murine hearts. H9c2- and murine cardiomyocytes were exposed to hypoxic conditions using a hypoxia chamber. Microvesicles were isolated by differential centrifugation and analysed by flow cytometry. Next-generation-sequencing was performed to determine the miRNA-expression profile in H9c2 CMV compared to their parent cells. Microvesicles were incubated with a co-culture model of the liver consisting of THP-1 macrophages and HepG2 cells. IL-6 and CRP expression in the co-culture was assessed by qPCR and ELISA. CMV contain a distinct pattern of miRNA compared to their parent cells including many inflammation-related miRNA. CMV induced IL-6 expression in THP-1 macrophages alone and CRP expression in the hepatic co-culture model. MV from hypoxic cardiomyocytes can mediate CRP expression in a hepatic co-culture model. Further studies will have to show whether these effects are reproducible in-vivo.
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http://dx.doi.org/10.1007/s11239-020-02156-xDOI Listing
October 2020

Extracellular HtrA2 Induces Apoptosis in Human Umbilical Vein Endothelial Cells.

Int J Mol Sci 2019 Oct 31;20(21). Epub 2019 Oct 31.

Department of Cardiology and Angiology I, Heart Center Freiburg University, Faculty of Medicine, University of Freiburg, Freiburg 79106, Germany.

The serine protease high-temperature-required protein A2 (HtrA2) has been identified as a key intracellular molecule promoting apoptosis in cells during ischemia reperfusion (IR) injury. IR injury in ST-segment elevation myocardial infarction (STEMI) contributes to overall myocardial damage. HtrA2 has further been shown to be significantly increased in the serum of patients with STEMI. In the present pilot study, we use human umbilical vein endothelial cells (HUVECs) to investigate whether extracellular HtrA2 induces apoptosis using Annexin V staining. Furthermore, we examine whether HtrA2 is released extracellularly after staurosporine-induced apoptosis using ELISA. We find that HtrA2 is released upon induction of apoptosis by staurosporine into the cell culture medium. Furthermore, treatment of HUVECs with extracellular HtrA2-induces apoptosis, while the addition of anti-HtrA2 antibodies reduces both HtrA2- and staurosporine-induced endothelial cell apoptosis. In conclusion, we show here that extracellular HtrA2 induces apoptosis in human endothelial cells, although the exact molecular mechanisms have to be investigated in future.
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http://dx.doi.org/10.3390/ijms20215446DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6862081PMC
October 2019

Semaphorin 3F Promotes Transendothelial Migration of Leukocytes in the Inflammatory Response After Survived Cardiac Arrest.

Inflammation 2019 Aug;42(4):1252-1264

Department of Cardiology and Angiology I, Heart Center Freiburg University, Faculty of Medicine, University of Freiburg, Hugstetter Strasse 55, 79106, Freiburg im Breisgau, Germany.

Leukocyte transmigration through the blood vessel wall is a fundamental step of the inflammatory response and requires expression of adhesion molecule PECAM-1. Accumulating evidence implicates that semaphorin (Sema) 3F and its receptor neuropilin (NRP) 2 are central regulators in vascular biology. Herein, we assess the role of Sema3F in leukocyte migration in vitro and in vivo. To determine the impact of Sema3F on leukocyte recruitment in vivo, we used the thioglycollate-induced peritonitis model. After the induction of peritonitis, C57BL/6 mice were intraperitoneally (i.p.) injected daily with recombinant Sema3F or solvent for 3 days. Compared with solvent-treated controls, leukocyte count was increased in the peritoneal lavage of Sema3F-treated mice indicating that Sema3F promotes leukocyte extravasation into the peritoneal cavity. In line with this observation, stimulation of human endothelial cells with Sema3F enhanced the passage of peripheral blood mononuclear cells (PBMCs) through the endothelial monolayer in the transwell migration assays. Conversely, silencing of endothelial Sema3F by siRNA transfection dampened diapedesis of PBMCs through the endothelium in vitro. xMechanistically, Sema3F induced upregulation of adhesion molecule PECAM-1 in endothelial cells and in murine heart tissue shown by immunofluorescence and western blotting. The inhibition of PECAM-1 by blocking antibody HEC7 blunted Sema3F-induced leukocyte migration in transwell assays. SiRNA-based NRP2 knockdown reduced PECAM-1 expression and migration of PBMCs in Sema3F-treated endothelial cells, indicating that PECAM-1 expression and leukocyte migration in response to Sema3F depend on endothelial NRP2. To assess the regulation of Sema3F in human inflammatory disease, we collected serum samples of patients from day 0 to day 7 after survived out-of-hospital cardiac arrest (OHCA, n = 41). First, we demonstrated enhanced migration of PBMCs through endothelial cells exposed to the serum of patients after OHCA in comparison to the serum of patients with stable coronary artery disease or healthy volunteers. Remarkably, serum samples of OHCA patients contained significantly higher Sema3F protein levels compared with CAD patients (CAD, n = 37) and healthy volunteers (n = 11), suggesting a role of Sema3F in the pathophysiology of the inflammatory response after OHCA. Subgroup analysis revealed that elevated serum Sema3F levels after ROSC are associated with decreased survival, myocardial dysfunction, and prolonged vasopressor therapy, clinical findings that determine the outcome of post-resuscitation period after OHCA. The present study provides novel evidence that endothelial Sema3F controls leukocyte recruitment through a NRP2/PECAM-1-dependent mechanism. Sema3F serum concentrations are elevated following successful resuscitation suggesting that Sema3F might be involved in the inflammatory response after survived OHCA. Targeting the Sema3F/NRP2/PECAM-1 pathway could provide a novel approach to abolish overwhelming inflammation after resuscitation.
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http://dx.doi.org/10.1007/s10753-019-00985-4DOI Listing
August 2019

Endothelial cell mineralocorticoid receptors oppose VEGF-induced gene expression and angiogenesis.

J Endocrinol 2019 01 19;240(1):15-26. Epub 2019 Nov 19.

L Hein, Institute of experimental and clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany.

Aldosterone is a key factor in adverse cardiovascular remodeling by acting on the mineralocorticoid receptor (MR) in different cell types. Endothelial MR activation mediates hypertrophy, inflammation and fibrosis. Cardiovascular remodeling is often accompanied by impaired angiogenesis, which is a risk factor for the development of heart failure. In this study, we evaluated the impact of MR in endothelial cells on angiogenesis. Deoxycorticosterone acetate (DOCA)-induced hypertension was associated with capillary rarefaction in the heart of WT mice but not of mice with cell type-specific MR deletion in endothelial cells. Consistently, endothelial MR deletion prevented the inhibitory effect of aldosterone on the capillarization of subcutaneously implanted silicon tubes and on capillary sprouting from aortic ring segments. We examined MR-dependent gene expression in cultured endothelial cells by RNA-seq and identified a cluster of differentially regulated genes related to angiogenesis. We found opposing effects on gene expression when comparing activation of the mineralocorticoid receptor in ECs to treatment with vascular endothelial growth factor (VEGF), a potent activator of angiogenesis. In conclusion, we demonstrate here that activation of endothelial cell MR impaired angiogenic capacity and lead to capillary rarefaction in a mouse model of MR-driven hypertension. MR activation opposed VEGF-induced gene expression leading to the dysregulation of angiogenesis-related gene networks in endothelial cells. Our findings underscore the pivotal role of endothelial cell MR in the pathophysiology of hypertension and related heart disease.
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http://dx.doi.org/10.1530/JOE-18-0494DOI Listing
January 2019

The effect of oxygen in Sirt3-mediated myocardial protection: a proof-of-concept study in cultured cardiomyoblasts.

J Thromb Thrombolysis 2018 Jul;46(1):102-112

Department of Cardiology, University Heart Center Zurich, University Hospital Zurich, Ramistr. 100, 8098, Zurich, Switzerland.

Sirtuin 3 is a nicotinamide adenine dinucleotide dependent mitochondrial deacetylase that governs mitochondrial metabolism and oxidative defense. The demise in myocardial function following myocardial ischemia has been associated with mitochondrial dysfunction. Sirt3 maintains myocardial contractile function and protects from cardiac hypertrophy. The role of Sirt3 in ischemia is controversial. Our objective was to understand, under what circumstances Sirt3 is protective in different facets of ischemia, using an in vitro proof-of-concept approach based on simulated ischemia in cultured cardiomyoblasts. Cultured H9c2 cardiomyoblasts were subjected to hypoxia and/or serum deprivation, the combination of which we refer to as simulated ischemia. Apoptosis, as assessed by Annexin V staining in life-cell imaging and propidium-iodide inclusion in flow cytometry, was enhanced following simulated ischemia. Interestingly, serum deprivation was a stronger trigger of apoptosis than hypoxia. Knockdown of Sirt3 further increased apoptosis upon serum deprivation, whereas no such effect occurred upon additional hypoxia. Similarly, only upon serum deprivation but not upon simulated ischemia, silencing of Sirt3 led to a deterioration of mitochondrial function in extracellular flux analysis. In the absence of oxygen these Sirt3-dependent effects were abolished. These data indicate, that Sirt3-mediated myocardial protection is oxygen-dependent. Thus, mitochondrial respiration takes center-stage in Sirt3-dependent prevention of stress-induced myocardial damage.
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http://dx.doi.org/10.1007/s11239-018-1677-3DOI Listing
July 2018

Extracellular bone morphogenetic protein modulator BMPER and twisted gastrulation homolog 1 preserve arterial-venous specification in zebrafish blood vessel development and regulate Notch signaling in endothelial cells.

FEBS J 2018 04 9;285(8):1419-1436. Epub 2018 Mar 9.

Department of Cardiology and Angiology I, Heart Center Freiburg University, Faculty of Medicine, University Freiburg, Germany.

The bone morphogenetic protein (BMP) signaling pathway plays a central role during vasculature development. Mutations or dysregulation of the BMP pathway members have been linked to arteriovenous malformations. In the present study, we investigated the effect of the BMP modulators bone morphogenetic protein endothelial precursor-derived regulator (BMPER) and twisted gastrulation protein homolog 1 (TWSG1) on arteriovenous specification during zebrafish development and analyzed downstream Notch signaling pathway in human endothelial cells. Silencing of bmper and twsg1b in zebrafish embryos by morpholinos resulted in a pronounced enhancement of venous ephrinB4a marker expression and concomitant dysregulated arterial ephrinb2a marker expression detected by in situ hybridization. As arteriovenous specification was disturbed, we assessed the impact of BMPER and TWSG1 protein stimulation on the Notch signaling pathway on endothelial cells from different origin. Quantitative real-time PCR (qRT-PCR) and western blot analysis showed increased expression of Notch target gene hairy and enhancer of split, HEY1/2 and EPHRINB2. Consistently, silencing of BMPER in endothelial cells by siRNAs decreased Notch signaling and downstream effectors. BMP receptor antagonist DMH1 abolished BMPER and BMP4 induced Notch signaling pathway activation. In conclusion, we found that in endothelial cells, BMPER and TWSG1 are necessary for regular Notch signaling activity and in zebrafish embryos BMPER and TWSG1 preserve arteriovenous specification to prevent malformations.
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http://dx.doi.org/10.1111/febs.14414DOI Listing
April 2018

Cardiac Endothelial Cell Transcriptome.

Arterioscler Thromb Vasc Biol 2018 03 4;38(3):566-574. Epub 2018 Jan 4.

From the Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine (A.L., S.B., L.D., L.H.), Heart Center Freiburg University, Department of Cardiology and Angiology I, Faculty of Medicine (A.L., M.M., C.B.), and BIOSS Centre for Biological Signaling Studies (L.H.), University of Freiburg, Germany.

Objective: Endothelial cells (ECs) are a highly specialized cell type with marked diversity between different organs or vascular beds. Cardiac ECs are an important player in cardiac physiology and pathophysiology but are not sufficiently characterized yet. Thus, the aim of the present study was to analyze the cardiac EC transcriptome.

Approach And Results: We applied fluorescence-assisted cell sorting to isolate pure ECs from adult mouse hearts. RNAseq revealed 1288 genes predominantly expressed in cardiac ECs versus heart tissue including several transcription factors. We found an overrepresentation of corresponding transcription factor binding motifs within the promotor region of EC-enriched genes, suggesting that they control the EC transcriptome. Cardiac ECs exhibit a distinct gene expression profile when compared with renal, cerebral, or pulmonary ECs. For example, we found the /, and signaling cascade higher expressed in cardiac ECs which is a key regulator of fatty acid uptake and involved in the development of atherosclerosis.

Conclusions: The results from this study provide a comprehensive resource of gene expression and transcriptional control in cardiac ECs. The cardiac EC transcriptome exhibits distinct differences in gene expression compared with other cardiac cell types and ECs from other organs. We identified new candidate genes that have not been investigated in ECs yet as promising targets for future evaluation.
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http://dx.doi.org/10.1161/ATVBAHA.117.310549DOI Listing
March 2018

MicroRNA-100 Suppresses Chronic Vascular Inflammation by Stimulation of Endothelial Autophagy.

Circ Res 2018 02 5;122(3):417-432. Epub 2017 Dec 5.

From the Department of Cardiology and Angiology I, Heart Center Freiburg University, Faculty of Medicine, University of Freiburg, Germany (F.P., C.H., X.B., C.J., S.K., C.S., L.S., J.M., M.J., T.H., M.M., C.B., S.G.); Laboratory of Clinical Chemistry and Haematology, University Medical Center Utrecht, The Netherlands (I.H., G.P.); and Department of Hematology, Oncology, and Stem Cell Transplantation, Medical Center, Faculty of Medicine, University of Freiburg, Germany (J.M., R.Z.).

Rationale: The interaction of circulating cells within the vascular wall is a critical event in chronic inflammatory processes, such as atherosclerosis, but the control of the vascular inflammatory state is still largely unclear.

Objective: This study was undertaken to characterize the function of the endothelial-enriched microRNA miR-100 during vascular inflammation and atherogenesis.

Methods And Results: Based on a transcriptome analysis of endothelial cells after miR-100 overexpression, we identified miR-100 as a potent suppressor of endothelial adhesion molecule expression, resulting in attenuated leukocyte-endothelial interaction in vitro and in vivo as shown by flow cytometry and intravital imaging. Mechanistically, miR-100 directly repressed several components of mammalian target of rapamycin complex 1-signaling, including mammalian target of rapamycin and raptor, which resulted in a stimulation of endothelial autophagy and attenuated nuclear factor κB signaling in vitro and in vivo. In a low-density lipoprotein receptor-deficient atherosclerotic mouse model, pharmacological inhibition of miR-100 resulted in enhanced plaque lesion formation and a higher macrophage content of the plaque, whereas a systemic miR-100 replacement therapy had protective effects and attenuated atherogenesis, resulting in a decrease of plaque area by 45%. Finally, analysis of miR-100 expression in >70 samples obtained during carotid endarterectomy revealed that local miR-100 expression was inversely correlated with inflammatory cell content in patients.

Conclusions: In summary, we describe an anti-inflammatory function of miR-100 in the vascular response to injury and inflammation and identify an important novel modulator of mammalian target of rapamycin signaling and autophagy in the vascular system. Our findings of miR-100 as a potential protective anti-athero-miR suggest that the therapeutic replacement of this microRNA could be a potential strategy for the treatment of chronic inflammatory diseases, such as atherosclerosis, in the future.
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http://dx.doi.org/10.1161/CIRCRESAHA.117.311428DOI Listing
February 2018

Endothelial BMP4 Regulates Leukocyte Diapedesis and Promotes Inflammation.

Inflammation 2017 Dec;40(6):1862-1874

Department of Cardiology and Angiology I, Heart Center Freiburg University, Faculty of Medicine, University of Freiburg, Hugstetter Strasse 55, 79106, Freiburg im Breisgau, Germany.

Leukocyte recruitment is a fundamental event in the response of the innate immune system to injury. This process is promoted in part by the opening of endothelial cell adherens junctions that allows leukocyte extravasation through gaps between adjacent endothelial cells. VE-cadherin is a key component of endothelial cell adherens junctions and a negative regulator of leukocyte emigration. Accumulating evidence implicates bone morphogenetic protein (BMP) 4 as a critical regulator in vascular biology, but its role in leukocyte extravasation in vitro and in vivo has not been investigated so far. To assess the impact of BMP4 on leukocyte emigration in vivo, we used the thioglycollate-induced peritonitis model. C57BL/6 mice were intraperitoneally (i.p.) injected with recombinant BMP4 in addition to thioglycollate. Compared to solvent-treated controls, we observed higher accumulation of leukocytes in the peritoneal lavage of BMP4-treated mice indicating that BMP4 promotes leukocyte diapedesis into the inflamed peritoneal cavity. Endothelial cell-specific deletion of BMP4 in mice markedly diminished leukocyte diapedesis following thioglycollate administration suggesting that endothelial BMP4 is required for leukocyte recruitment. Consistent with these in vivo results, transwell migration assays with human umbilical vein endothelial cells (HUVECs) in vitro revealed that recombinant BMP4 enhanced leukocyte transmigration through the endothelial monolayer. Conversely, silencing of endothelial BMP4 by siRNA dampened leukocyte diapedesis in vitro. Mechanistic studies showed that loss of BMP4 improved endothelial junction stability by upregulation of VE-cadherin expression in vitro and in vivo. Vice versa, treatment of HUVECs with recombinant BMP4 decreased expression of VE-cadherin and impaired endothelial junction stability shown by Western blotting and immunocytochemistry. Finally, severe endothelial damage in HUVECs in response to serum of patients collected 24 h after survived cardiac arrest was accompanied by increase in leukocyte migration in transwell assays and activation of the BMP pathway most probably by upregulation of endothelial BMP4 RNA and protein expression. Collectively, the present study provides novel evidence that endothelial BMP4 controls leukocyte recruitment through a VE-cadherin-dependent mechanism and that BMP4-induced inflammation might be involved in the pathogenesis of endothelial cell damage following successful resuscitation after cardiac arrest.
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http://dx.doi.org/10.1007/s10753-017-0627-0DOI Listing
December 2017

Bone morphogenetic protein 4 regulates microRNAs miR-494 and miR-126-5p in control of endothelial cell function in angiogenesis.

Thromb Haemost 2017 04 26;117(4):734-749. Epub 2017 Jan 26.

Jennifer Susanne Esser, PhD, University Heart Center Freiburg, Department of Cardiology and Angiology I, Cardiovascular Biology Group, Breisacher Str. 33, 79106 Freiburg, Germany, Tel.: +49 76127070440, Fax: +49 76127070450, E-mail:

MicroRNAs are small non-coding RNAs that negatively regulate posttranscriptional gene expression. Several microRNAs have been described to regulate the process of angiogenesis. Previously, we have shown that bone morphogenetic protein 4 (BMP4) increased the pro-angiogenic activity of endothelial cells. In this project, we now investigated how the pro-angiogenic BMP4 effect is mediated by microRNAs. First, we performed a microRNA array with BMP4-stimulated human umbilical vein endothelial cells (HUVECs). Among the top-regulated microRNAs, we detected a decreased expression of miR-494 and increased expression of miR-126-5p. Next, we analysed the canonical Smad and alternative signalling pathways, through which BMP4 would regulate miR-126-5p and miR-494 expression. Furthermore, the functional effect of miR-494 and miR-126-5p on endothelial cells was investigated. MicroRNA-494 overexpression decreased endothelial cell proliferation, migration and sprout formation. Consistently, miR-494 inhibition increased endothelial cell function. As potential miR-494 targets, bFGF and BMP endothelial cell precursor-derived regulator (BMPER) were identified and confirmed by western blot. Luciferase assays showed direct miR-494 binding in BMPER 3'UTR. In contrast, miR-126-5p overexpression increased pro-angiogenic endothelial cell behaviour and, accordingly, miR-126-5p inhibition decreased endothelial cell function. As a direct miR-126-5p target we identified the anti-angiogenic thrombospondin-1 which was confirmed by western blot analysis and luciferase assays. In the Matrigel plug assay application of antagomiR-494 increased endothelial cell ingrowth, whereas antagomiR-126-5p treatment decreased cell ingrowth in vivo. Taken together, through differential regulation of the anti-angiomiR-494 and the angiomiR-126-5p by BMP4 both microRNAs contribute to the pro-angiogenic BMP4 effect on endothelial cells.
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http://dx.doi.org/10.1160/TH16-08-0643DOI Listing
April 2017

The neuronal transcription factor NPAS4 is a strong inducer of sprouting angiogenesis and tip cell formation.

Cardiovasc Res 2017 02 12;113(2):222-223. Epub 2017 Jan 12.

Cardiovascular Biology Group, Department of Cardiology and Angiology I, Heart Center, Faculty of Medicine, University of Freiburg, Breisacher Str.33, 79106 Freiburg, Germany;

Rationale: Regarding branching morphogenesis, neurogenesis and angiogenesis share common principle mechanisms and make use of the same molecules. Therefore, the investigation of neuronal molecules involved in vascular morphogenesis provides new possibilities for pro-angiogenic approaches in cardiovascular diseases.

Objective: In this study, we investigated the role of the neuronal transcription factor NPAS4 in angiogenesis.

Methods And Results: Here, we demonstrate that the neuronal transcription factor NPAS4 is expressed in endothelial cells of different origin using reverse transcription PCR and western blot analysis. To investigate how NPAS4 affects endothelial cell function, NPAS4 was overexpressed by plasmid transfection or depleted from human umbilical vein endothelial cells (HUVECs) by specific siRNAs. In vitro HUVEC sprouting assays showed that sprouting and branching of endothelial cells was enhanced by NPAS4 overexpression. Consistently, silencing of NPAS4 resulted in reduced HUVEC sprouting and branching. Mechanistically, we identified as target gene vascular endothelial adhesion molecule VE-cadherin to be involved in the pro-angiogenic function of NPAS4. In endothelial cell mosaic spheroid sprouting assays, NPAS4 was involved in tip cell formation. In vivo experiments in mouse and zebrafish confirmed our in vitro findings. NPAS4-deficient mice displayed reduced ingrowth of endothelial cells in the Matrigel plug assay. Consistent with a regulatory role of NPAS4 in endothelial cell function silencing of NPAS4 in zebrafish by specific morpholinos resulted in perturbed intersegmental vessels growth.

Conclusions: NPAS4 is expressed in endothelial cells, regulates VE-cadherin expression and regulates sprouting angiogenesis.
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http://dx.doi.org/10.1093/cvr/cvw248DOI Listing
February 2017

Bone Morphogenetic Protein-Modulator BMPER Regulates Endothelial Barrier Function.

Inflammation 2017 Apr;40(2):442-453

Department of Cardiology and Angiology, Heart Center Freiburg University, Hugstetter Strasse 55, 79106, Freiburg im Breisgau, Germany.

The endothelium serves as a selective barrier and controls the exchange of nutrients, hormones, and leukocytes between blood and tissues. Molecular mechanisms contributing to the pathogenesis of endothelial barrier dysfunction remain incompletely understood. Accumulating evidence implicates bone morphogenetic protein (BMP)-modulator BMPER as a key regulator in endothelial biology. Herein, we analyze the impact of BMPER in the control of endothelial barrier function. To assess the role of BMPER in vascular barrier function in mice, we measured the leakage of Evans blue dye from blood into interstitial lung tissue. BMPER mice exhibited a significantly higher degree of vascular leak compared with wild-type siblings. In accordance with our in vivo observation, siRNA-based BMPER knockdown in human umbilical endothelial cells increased endothelial permeability measured by FITC-dextran passage in transwell assays. Mechanistically, BMPER knockdown reduced the expression of VE-cadherin, a pivotal component of endothelial adherens junctions. Conversely, recombinant human BMPER protein upregulated VE-cadherin protein levels and improved endothelial barrier function in transwell assays. The effects of BMPER knockdown on VE-cadherin expression and endothelial permeability were induced by enhanced BMP activity. Supporting this notion, activation of BMP4-Smad-Id1 signaling reduced VE-cadherin levels and impaired endothelial barrier function in vitro. In vivo, Evans blue dye accumulation was higher in the lungs of BMP4-treated C57BL/6 mice compared to controls indicating that BMP4 increased vascular permeability. High levels of BMPER antagonized BMP4-Smad5-Id1 signaling and prevented BMP4-induced downregulation of VE-cadherin and endothelial leakage, suggesting that BMPER exerts anti-BMP effects and restores endothelial barrier function. Taken together, this data demonstrates that BMPER-modulated BMP pathway activity regulates VE-cadherin expression and vascular barrier function.
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http://dx.doi.org/10.1007/s10753-016-0490-4DOI Listing
April 2017

MnTBAP increases BMPR-II expression in endothelial cells and attenuates vascular inflammation.

Vascul Pharmacol 2016 09 8;84:67-73. Epub 2016 Jul 8.

Department of Cardiology and Angiology I, Heart Center, Medical Faculty, University of Freiburg, Freiburg, Germany. Electronic address:

Aims: The endothelium plays an important role during vascular inflammation. Previous data have demonstrated a high expression level of manganese-superoxide dismutase (MnSOD) in endothelial cells and suggested an important role of MnSOD in several cardiovascular diseases. Manganese (III) tetrakis (4-benzoic acid) porphyrin (MnTBAP) has been shown to mimic some of the effects of MnSOD and prevented the development of diabetes and obesity. However, its effect on vascular inflammation and the underlying mechanism is still unknown.

Methods And Results: Leukocyte adhesion was evaluated in-vivo and in-vitro using dynamic flow chamber and intravital microscopy in mice. Expression of adhesion molecules induced by TNFα and adhesion of leukocytes to the vessel wall were inhibited by MnTBAP. The anti-inflammatory effect of MnTBAP was partly mediated by up-regulation of the BMPR-II and Smad dependent pathway. Additionally, MnTBAP decelerated the turn-over of endogenous BMPR-II.

Conclusion: Our data demonstrate that MnTBAP activates Smad signaling, preserves the turn-over of BMPR-II and elicits anti-inflammatory effects in endothelial cells, partly mediated by BMPR-II. This finding suggests a potential therapeutic impact of MnTBAP in the treatment of vascular inflammation.
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http://dx.doi.org/10.1016/j.vph.2016.07.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5563469PMC
September 2016

High platelet reactivity after P2Y12-inhibition in patients with atrial fibrillation and coronary stenting.

J Thromb Thrombolysis 2016 Nov;42(4):558-65

Cardiology and Angiology I, Heart Center, Freiburg University, Hugstetter Str. 55, 79106, Freiburg, Germany.

High platelet reactivity (HPR) after P2Y12-inhibition in patients undergoing coronary stenting is associated with an increased risk for thromboembolic events and coronary death. So far it is not known how HPR affects the clinical outcome of different treatment strategies in patients with atrial fibrillation (AF) undergoing coronary stenting. In this single centre, observational study the antiplatelet effect of P2Y12-inhibitors in AF patients undergoing coronary stenting was investigated using impedance aggregometry. Patients received either dual antiplatelet therapy (DAPT) or triple therapy (TT). HPR was defined as the ratio of ADP-to TRAP-induced aggregation (r-ADP-agg) ≥50 %. Thromboembolic and bleeding events were assessed within the first 30 days after stenting. Out of 910 screened patients 167 patients were available for the present analysis. HPR was found in 5 of 43 (12 %) patients treated with DAPT and in 18 of 124 (15 %) patients treated with TT. In patients receiving TT, HPR was not a risk factor for thromboembolic events compared to patients with adequate response to P2Y12-inhibitors (6 vs. 8 %, p = 0.712). There was a trend for less bleeding events in patients with HPR compared to r-ADP-agg <50 % in the TT group (0 vs. 16 %, p = 0.077). Our data suggest that HPR after P2Y12-antagonism in patients receiving TT due to AF and coronary stenting might protect from bleeding without increasing thromboembolic risk. Future studies will need to investigate if patients with AF receiving coronary stenting benefit from a reduction of antithrombotic therapy.
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http://dx.doi.org/10.1007/s11239-016-1397-5DOI Listing
November 2016

Dabigatran and rivaroxaban do not affect AA- and ADP-induced platelet aggregation in patients receiving concomitant platelet inhibitors.

J Thromb Thrombolysis 2016 Aug;42(2):161-6

Cardiology and Angiology I, Heart Center, Freiburg University, Hugstetter Str. 55, 79106, Freiburg - Bad Krozingen, Germany.

Dabigatran and rivaroxaban are novel, vitamin K-independent oral anticoagulants (NOACs) and act via antagonism of the coagulation factor (F) IIa (dabigatran) or FXa (rivaroxaban), respectively. Compared to vitamin-K-antagonists, NOACs have shown non-inferiority of risk and benefit in patients with non valvular atrial fibrillation (AF). In clinical practice there is increasing use of NOACs combined with platelet inhibitors in patients with AF and coronary artery disease. However, whether NOACs affect the function of platelet inhibitors remains incompletely known. This observational study aimed to assess the platelet function in patients receiving dabigatran or rivaroxaban and concomitant platelet inhibitors. A single centre observational study was performed analysing the platelet aggregation of patients treated with dabigatran or rivaroxaban with or without concomitant platelet inhibitors. Measurements before the initiation of NOAC therapy served as the respective control group. Platelet aggregation was measured by multiple electrode aggregometry and was induced with adenosine diphosphate (ADP, 6.5 µM) and arachidonic acid (AA, 0.5 mM), respectively. In order to evaluate whether NOACs interact with platelet inhibition by ASA or the P2Y12-antagonist clopidogrel, 87 patients were grouped according to their concomitant antiplatelet medication. Comparing the ADP- and AA-induced platelet aggregation in patients without concomitant platelet inhibitors (n = 45) no significant differences under therapy with dabigatran (d) or rivaroxaban (r) compared to the control group (c) were observed. In patients taking clopidogrel as a concomitant platelet inhibitor (n = 21), neither dabigatran nor rivaroxaban affected the ADP-induced platelet aggregation (c 20 ± 11, d 21 ± 14, r 18 ± 8 AU*min, p = 0.200). Patients receiving dabigatran or rivaroxaban in combination with ASA (n = 42; 21 ASA only, 21 ASA + clopidogrel) showed no significant differences of the AA-induced aggregation compared to the control group (c 10 ± 8, d 9 ± 7, r 10 ± 8 AU*min, p = 0.810). The antiplatelet effects of ASA and clopidogrel monitored by AA- or ADP-induced platelet aggregation were not affected by NOAC therapy.
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http://dx.doi.org/10.1007/s11239-016-1350-7DOI Listing
August 2016

The Ratio of ADP- to TRAP-Induced Platelet Aggregation Quantifies P2Y12-Dependent Platelet Inhibition Independently of the Platelet Count.

PLoS One 2016 17;11(2):e0149053. Epub 2016 Feb 17.

Heart Center Freiburg University, Cardiology and Angiology I, Freiburg-Bad Krozingen, Germany.

Objective: This study aimed to assess the association of clinical factors with P2Y12-dependent platelet inhibition as monitored by the ratio of ADP- to TRAP-induced platelet aggregation and conventional ADP-induced aggregation, respectively.

Background: Controversial findings to identify and overcome high platelet reactivity (HPR) after coronary stent-implantation and to improve clinical outcome by tailored anti-platelet therapy exist. Monitoring anti-platelet therapy ex vivo underlies several confounding parameters causing that ex vivo platelet aggregation might not reflect in vivo platelet inhibition.

Methods: In a single centre observational study, multiple electrode aggregometry was performed in whole blood of patients after recent coronary stent-implantation. Relative ADP-induced aggregation (r-ADP-agg) was defined as the ratio of ADP- to TRAP- induced aggregation reflecting the individual degree of P2Y12-mediated platelet reactivity.

Results: Platelet aggregation was assessed in 359 patients. Means (± SD) of TRAP-, ADP-induced aggregation and r-ADP-agg were 794 ± 239 AU*min, 297 ± 153 AU*min and 37 ± 14%, respectively. While ADP- and TRAP-induced platelet aggregation correlated significantly with platelet count (ADP: r = 0.302; p<0.001; TRAP: r = 0.509 p<0.001), r-ADP-agg values did not (r = -0.003; p = 0.960). These findings were unaltered in multivariate analyses adjusting for a range of factors potentially influencing platelet aggregation. The presence of an acute coronary syndrome and body weight were found to correlate with both ADP-induced platelet aggregation and r-ADP-agg.

Conclusion: The ratio of ADP- to TRAP-induced platelet aggregation quantifies P2Y12-dependent platelet inhibition independently of the platelet count in contrast to conventional ADP-induced aggregation. Furthermore, r-ADP-agg was associated with the presence of an acute coronary syndrome and body weight as well as ADP-induced aggregation. Thus, the r-ADP-agg is a more valid reflecting platelet aggregation and potentially prognosis after coronary stent-implantation in P2Y12-mediated HPR than conventional ADP-induced platelet aggregation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0149053PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4757031PMC
July 2016

Platelet reactivity after administration of third generation P2Y12-antagonists does not depend on body weight in contrast to clopidogrel.

J Thromb Thrombolysis 2016 Jul;42(1):84-9

Cardiology and Angiology I, Heart Center, Freiburg University, Hugstetter Str. 55, 79106, Freiburg - Bad Krozingen, Germany.

The current standard of antiplatelet therapy for patients with myocardial infarction (MI) includes the P2Y12-receptor antagonist clopidogrel, prasugrel or ticagrelor. While it has been shown that platelet reactivity after clopidogrel administration depends on factors such as body weight, it is not known if these factors have an effect on the activity of prasugrel or ticagrelor. Thus, this study aimed to analyse factors associated with high residual platelet reactivity after administration of third generation P2Y12-antagonists compared to clopidogrel. In a single centre registry the antiplatelet effect of clopidogrel, prasugrel or ticagrelor was investigated by aggregometry in patients after MI. To assess the overall capacity of platelet aggregation whole blood was induced with thrombin receptor activating peptide (TRAP; 32 µM). To specifically quantify the effect of P2Y12-antagonists, blood was stimulated with 6.4 µM adenosine diphophosphate (ADP). Relative ADP induced aggregation (r-ADP-agg) was defined as the ADP-TRAP-ratio to reflect an individual degree of P2Y12-dependent platelet inhibition. Platelet function of 238 patients was analysed [clopidogrel (n = 58), prasugrel (n = 65), ticagrelor (n = 115)]. It was found that the r-ADP-agg correlated significantly with body weight in patients after clopidogrel administration (r = 0.423; p < 0.001). In contrast, this association was not present in patients after prasugrel (r = -0.117; p = 0.354) or ticagrelor (r = -0.082; p = 0.382) administration. Comparison of the correlation coefficients showed a significant difference (p = 0.003). In contrast to clopidogrel, platelet reactivity after administration of prasugrel or ticagrelor does not depend on body weight in patients after MI. Hence, our mechanistic data support the results of large clinical trials indicating that patients with high body weight do not need to be treated with increased doses of third generation P2Y12-antagonists to achieve sufficient platelet inhibition (registry for patients after myocardial infarction treated with antiplatelet agents; DRKS00003146).
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http://dx.doi.org/10.1007/s11239-016-1340-9DOI Listing
July 2016

TRAP-induced platelet aggregation is enhanced in cardiovascular patients receiving dabigatran.

Thromb Res 2016 Feb 1;138:63-68. Epub 2015 Nov 1.

Heart Center, Freiburg University, Cardiology and Angiology I, Freiburg-Bad Krozingen, Germany.

Background/objectives: Novel (or non-vitamin K antagonist) oral anti-coagulants (NOACs) are antagonists of coagulation factors (F) Xa (rivaroxaban) or IIa (dabigatran), and their non-inferiority compared with vitamin K antagonists has been demonstrated in patients with non-valvular atrial fibrillation. However, it is still not fully understood if and how dabigatran and rivaroxaban impact platelet function. This observational study aimed to assess platelet function in patients receiving dabigatran or rivaroxaban.

Methods/results: This was a single centre, observational study quantifying platelet aggregation in 90 patients treated with NOACs by multiple electrode aggregometry. The thrombin receptor activating peptide (TRAP)-induced platelet aggregation was significantly higher in 35 patients receiving dabigatran (d) compared with control (c) patients (d 108±31 vs. c 85±30arbitrary units [AU]∗min, p<0.001). Patients receiving rivaroxaban (r) showed no differences compared with the control group (r 88±32 vs. c 85±30AU∗min, p=0.335). In intraindividual time courses of 16 patients, a significantly higher aggregation was found after the administration of dabigatran (before vs. after; 83±29 vs. 100±31AU∗min, p=0.009).

Conclusion: In this observational study, the TRAP-induced platelet aggregation was enhanced in cardiovascular patients receiving dabigatran. This might be explained by a change in the expression profile of thrombin receptors on the surface of platelets. Rivaroxaban had no influence on platelet aggregation.
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http://dx.doi.org/10.1016/j.thromres.2015.10.038DOI Listing
February 2016

Deoxycorticosterone Acetate/Salt-Induced Cardiac But Not Renal Injury Is Mediated By Endothelial Mineralocorticoid Receptors Independently From Blood Pressure.

Hypertension 2016 Jan 9;67(1):130-8. Epub 2015 Nov 9.

From the Department of Cardiology and Angiology I, Heart Center (A.L., I.H., C.B., M.M.), Institute of Experimental and Clinical Pharmacology and Toxicology (A.L., D.F., S.B., R.G., L.H.), Renal Division, Department of Medicine (F.G., T.B.H.), and BIOSS Centre for Biological Signaling Studies (T.B.H., L.H.), University of Freiburg, Freiburg, Germany.

Chronic kidney disease has a tremendously increasing prevalence and requires novel therapeutic approaches. Mineralocorticoid receptor (MR) antagonists have proven highly beneficial in the therapy of cardiac disease. The cellular and molecular events leading to cardiac inflammation and remodeling are proposed to be similar to those mediating renal injury. Thus, this study was designed to evaluate and directly compare the effect of MR deletion in endothelial cells on cardiac and renal injury in a model of deoxycorticosterone acetate-induced hypertension. Endothelial MR deletion ameliorated deoxycorticosterone acetate/salt-induced cardiac remodeling. This was associated with a reduced expression of the vascular cell adhesion molecule Vcam1 in MR-deficient cardiac endothelial cells. Ambulatory blood pressure telemetry revealed that the protective effect of MR deletion was independent from blood pressure. Similar to the heart, deoxycorticosterone acetate/salt-induced severe renal injury, including inflammation, fibrosis, glomerular injury, and proteinuria. However, no differences in renal injury were observed between genotypes. In conclusion, MR deletion from endothelial cells ameliorated deoxycorticosterone acetate/salt-induced cardiac inflammation and remodeling independently from alterations in blood pressure but it did not affect renal injury. These findings suggest that the anti-inflammatory mechanism mediating organ protection after endothelial cell MR deletion is specific for the heart versus the kidney.
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http://dx.doi.org/10.1161/HYPERTENSIONAHA.115.06530DOI Listing
January 2016

Aortic root volume is associated with contained rupture of the aortic annulus in balloon-expandable transcatheter aortic valve replacement.

Catheter Cardiovasc Interv 2016 Mar 26;87(4):807-17. Epub 2015 Oct 26.

Department of Radiology, Center for Diagnostic and Therapeutic Radiology, University Hospital Freiburg, Germany.

Background: Aortic annulus rupture is a rare, but potentially fatal complication of transcatheter aortic valve replacement (TAVR), especially when it occurs by balloon-expandable devices. In order to improve the predictability of procedures and avoid ruptures we investigated whether or not the aortic root volume measures is a useful indicator of risk, and if it could be useful for the prosthesis size selection.

Methods And Results: From a retrospective series of 172 TAVR patients, seven experienced contained aortic annulus ruptures. The receiver operating curves were used to illustrate sensitivity and specificity of the different aortic annulus size and aortic root volume measures. The annulus area oversizing of ≥20% resulted in a sensitivity of 100%, specificity of 55.76%, and positive predictive value (PPV) of 8.75%. In patients receiving 26 mm prostheses, the aortic root volume (ARV <13600 mm(3)) provided a better specificity and PPV (79.63 and 18.52%, respectively). A two-step testing procedure considering the area derived average annulus diameter (Darea <23 mm) as a first separating parameter and then the ARV (<13,600 mm(3)) as a further indicator showed the most promising results with the PPV of 31.25%. Regardless of the procedure steps no false negative results were predicted.

Conclusions: Our data show that the ARV provides a better predictive value for correct prosthesis sizing than established annulus measurements, especially in 'borderline' annuli. We suggest a two-step testing procedure for prostheses size selection, considering Darea and ARV to minimize the risk of annulus rupture. Prospective studies and examination of larger datasets are warranted to confirm these findings.
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http://dx.doi.org/10.1002/ccd.26260DOI Listing
March 2016

In-hospital resource utilization in surgical and transcatheter aortic valve replacement.

BMC Cardiovasc Disord 2015 Oct 22;15:132. Epub 2015 Oct 22.

Department of Cardiology and Angiology I, Heart Center Freiburg University, Hugstetter Str. 55, 79106, Freiburg, Germany.

Background: Little is known about preoperative predictors of resource utilization in the treatment of high-risk patients with severe symptomatic aortic valve stenosis. We report results from the prospective, medical-economic "TAVI Calculation of Costs Trial".

Methods: In-hospital resource utilization was evaluated in 110 elderly patients (age ≥ 75 years) treated either with transfemoral (TF) or transapical (TA) transcatheter aortic valve implantation (TAVI, N = 83), or surgical aortic valve replacement (AVR, N = 27). Overall, 22 patient-specific baseline parameters were tested for within-group prediction of resource use.

Results: Baseline characteristics differed between groups and reflected the non-randomized, real-world allocation of treatment options. Overall procedural times were shortest for TAVI, intensive care unit (ICU) length of stay (LoS) was lowest for AVR. Length of total hospitalization since procedure (THsP) was lowest for TF-TAVI; 13.4 ± 11.4 days as compared to 15.7 ± 10.5 and 21.2 ± 15.4 days for AVR and TA-TAVI, respectively. For TAVI and AVR, EuroScore I remained the main predictor for prolonged THsP (p <0.01). Within the TAVI group, multivariate regression analyses showed that TA-TAVI was associated with a substantial increase in THsP (55 to 61 %, p <0.01). Additionally, preoperative aortic valve area (AVA) was identified as an independent predictor of prolonged THsP in TAVI patients, irrespective of risk scores (p <0.05).

Conclusions: Our results demonstrate significant heterogeneity in patients baseline characteristics dependent on treatment and corresponding differences in resource utilization. Prolonged ThsP is not only predicted by risk scores but also by baseline AVA, which might be useful in stratifying TAVI patients.

Trial Registration: German Clinical Trial Register Nr. DRKS00000797.
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http://dx.doi.org/10.1186/s12872-015-0118-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4619014PMC
October 2015

BMPER Promotes Epithelial-Mesenchymal Transition in the Developing Cardiac Cushions.

PLoS One 2015 29;10(9):e0139209. Epub 2015 Sep 29.

McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599, United States of America; New York-Presbyterian Hospital, New York City, New York, 10065, United States of America.

Formation of the cardiac valves is an essential component of cardiovascular development. Consistent with the role of the bone morphogenetic protein (BMP) signaling pathway in cardiac valve formation, embryos that are deficient for the BMP regulator BMPER (BMP-binding endothelial regulator) display the cardiac valve anomaly mitral valve prolapse. However, how BMPER deficiency leads to this defect is unknown. Based on its expression pattern in the developing cardiac cushions, we hypothesized that BMPER regulates BMP2-mediated signaling, leading to fine-tuned epithelial-mesenchymal transition (EMT) and extracellular matrix deposition. In the BMPER-/- embryo, EMT is dysregulated in the atrioventricular and outflow tract cushions compared with their wild-type counterparts, as indicated by a significant increase of Sox9-positive cells during cushion formation. However, proliferation is not impaired in the developing BMPER-/- valves. In vitro data show that BMPER directly binds BMP2. In cultured endothelial cells, BMPER blocks BMP2-induced Smad activation in a dose-dependent manner. In addition, BMP2 increases the Sox9 protein level, and this increase is inhibited by co-treatment with BMPER. Consistently, in the BMPER-/- embryos, semi-quantitative analysis of Smad activation shows that the canonical BMP pathway is significantly more active in the atrioventricular cushions during EMT. These results indicate that BMPER negatively regulates BMP-induced Smad and Sox9 activity during valve development. Together, these results identify BMPER as a regulator of BMP2-induced cardiac valve development and will contribute to our understanding of valvular defects.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0139209PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4587915PMC
June 2016