Accuracy of Devereaux and Teichholz formulas for left ventricular mass calculation in different geometric patterns: comparison with cardiac magnetic resonance imaging.

Left ventricular (LV) myocardial mass is important in the evaluation of cardiac remodeling and requires accurate assessment when performed on linear measurements in two-dimensional echocardiography (Echo). We aimed to compare the accuracy of the Devereaux formula (DEV) and the Teichholz formula (TEICH) in calculating LV myocardial mass in Echo using cardiac magnetic resonance (CMR) as the reference method. Based on preceding mathematical calculations, we identified primarily LV size rather than wall thickness as the main source of bias between DEV and TEICH in a retrospective derivation cohort (n = 1276). Although LV mass from DEV and TEICH were correlated with CMR, TEICH did not show a proportional bias as did DEV (- 2 g/m2 vs. + 22 g/m2). This could be validated in an independent prospective cohort (n = 226) with symptomatic non-ischemic heart failure. DEV systematically overestimated LV mass in all tiers of LV remodeling as compared to TEICH. In conclusion, the TEICH method accounts for the changes in LV geometry with increasing LV mass and thus better reflects the different pattern of LV remodeling than the DEV method. This has important clinical implications, as TEICH may be more appropriate for use in clinical practice, rather than DEV, currently recommended.

Myeloid PHD2 deficiency accelerates neointima formation via Hif-1α.

The key players of the hypoxic response are the hypoxia-inducible factors (Hif), whose α-subunits are tightly regulated by Prolyl-4-hydroxylases (PHD), predominantly by PHD2. Monocytes/Macrophages are involved in atherosclerosis but also restenosis and were found at hypoxic and sites of the lesion. Little is known about the role of the myeloid PHD2 in atherosclerosis and neointima formation. The study aimed to investigate the consequences of a myeloid deficiency of PHD2 in the process of neointima formation using an arterial denudation model. LysM-cre mice were crossed with PHD2fl/fl, PHD2fl/fl/Hif1αfl/fl and PHD2fl/fl/Hif2αfl/fl to get myeloid specific knockout of PHD2 and the Hif-α subunits. Denudation of the femoral artery was performed and animals were fed a western type diet afterwards with analysis of neointima formation 5 and 35 days after denudation. Increased neointima formation in myeloid PHD2 knockouts was observed, which was blunted by double-knockout of PHD2 and Hif1α whereas double knockout of PHD2 and Hif-2α showed comparable lesions to the PHD2 knockouts. Macrophage infiltration was comparable to the neointima formation, suggesting a more inflammatory reaction, and was accompanied by increased intimal VEGF-A expression. Collagen-content inversely correlated to the extent of neointima formation suggesting a destabilization of the plaque. This effect might be triggered by macrophage polarization. Therefore, in vitro results showed a distinct expression pattern in differentially polarized macrophages with high expression of Hif-1α, VEGF and MMP-1 in proinflammatory M1 macrophages. In conclusion, the results show that myeloid Hif-1α is involved in neointima hyperplasia. Our in vivo and in vitro data reveal a central role for this transcription factor in driving plaque-vascularization accompanied by matrix-degradation leading to plaque destabilization.

The predictive role of early CRP values for one-year mortality in the first 2 d after acute myocardial infarction.

BACKGROUND: An excessive inflammatory reaction after acute myocardial infarction (AMI) is known to be harmful. New anti-inflammatory therapies are required. PURPOSE: This study assessed the predictive role of early CRP in patients with STEMI. METHODS: A total of 1003 patients with STEMI were analysed. A total of 180 patients with proven infection were excluded. CRP after 12, 24 and 48 h after pain onset were evaluated. RESULTS: Of 823 patients, 103 (12.5%) died within one year after AMI. The deceased patients showed higher CRP, even after already 12 h (6 vs. 13 mg/l, p < .001), 24 h (13 vs. 25 mg/l, p < .001) and after 48 h (40 vs. 92 mg/l, p < .001). A CRP of ≥8 mg/l, 12 h after AMI, was found in 45% and was independently associated with long-term mortality (OR: 2.7, p = .03), after 24 h: CRP ≥ 18 mg/l in 44% (OR: 2.5, p = .03), after 48 h: CRP ≥ 53 mg/l in 44% (OR 1.9, p = .03). Early CRP values correlated strongly with the later maximum value of CRP (p < .001). CONCLUSIONS: Already early CRP values are accurate for risk-prediction following AMI. By identifying patients who are beginning to develop an excessive inflammatory response, it may be possible to identify those who benefit from anti-inflammatory therapies.

Purposeful use of multimodality imaging in the diagnosis of caseous mitral annular calcification: a case series report.

BACKGROUND: Caseous mitral annular calcification (CMAC) is a rare liquefactive variant of mitral annular calcification (MAC) and superficially mimics a cardiac vegetation or abscess. CMAC is viewed as a benign condition of MAC, while MAC has clinical implications for patients' lives. Correctly diagnosing CMAC is essential in order to avoid unnecessary interventions, cardiac surgery or even psychological suffering for the patient. CASE PRESENTATION: We report on 6 patients with suspected intra-cardiac masses of the mitral annulus that were referred to our institution for further clarification. A definitive diagnosis of CMAC was achieved by combining echocardiography (Echo), cardiac magnetic resonance imaging (MRI) and cardiac computed tomography (CT) for these patients. Echo assessed the mass itself and possible interactions with the mitral valve. MRI was useful in differentiating the tissue from other benign or malign neoplasms. CT revealed the typical structure of CMAC with a "soft" liquefied centre and an outer capsule with calcification. CONCLUSION: CMAC is a rare condition, and most clinicians and even radiologists are not familiar with it. CMAC can be mistaken for an intra-cardiac tumour, thombus, vegetation, or abscess. Non-invasive multimodality imaging (i.e. Echo, MRI, and CT) helps to establish a definitive diagnosis of CMAC and avoid unnecessary interventions especially in uncertain cases.

Frailty is associated with chronic inflammation and pro-inflammatory monocyte subpopulations.

AIM OF THE STUDY: Frail patients with high grade aortic valve stenosis (AS) undergoing Transcatheter Aortic Valve Implantation (TAVI) have an increased mortality. A connection between frailty and inflammation has been suggested. Monocyte subpopulations are associated with both cardiovascular diseases and chronic inflammatory diseases. This study investigates the association of frailty with monocyte subpopulations and systemic inflammatory parameters in elderly patients undergoing TAVI. METHODS: A total of 120 patients with symptomatic AS was examined. Before TAVI implantation, frailty was assessed by a bedside evaluation (eyeball test). In all patients a flow cytometry analysis has been performed. Monocyte subpopulations were defined as follows: classical (CD14++CD16-), intermediate (CD14++CD16+) and non-classical (CD14+CD16++). Expression of CD11b was measured as a marker for monocyte activation. Pro-inflammatory cytokines such as interleukin IL-8, as well as CRP were measured with Cytometric Bead Array or standard laboratory methods. RESULTS: 28 out of 120 patients were frail. These patients showed both, signs of elevated chronic systemic inflammation reflected by elevated CRP (3.7 (1.4-5.4) vs. 5.9 (3.7-29.1), p = 0.001) and an elevated level of intermediate monocytes (37 (24-54) vs. 53 (47-63), p = 0.001). At 6 months after TAVI, 19 of 120 patients died, primarily without relevant dysfunction of the implanted aortic valve. Mortality was significantly higher in the frail as compared with non-frail patients (9 of 28 frail patients vs. 10 of 92 non frail patients, p < 0.001). A binary logistic regression analysis validated frailty and intermediate monocytes as independent predictors for early mortality after TAVI. CONCLUSION: Chronic systemic inflammation and increased levels of intermediate monocytes are associated with frailty in old patients with severe aortic valve stenosis. Both the syndrome of frailty and elevated intermediate monocytes showed an association with early mortality after TAVI.

Percutaneous Left Ventricular Assist Device Leads to Heart Rhythm Stabilisation in Cardiogenic Shock: Results from the Dresden Impella Registry.

BACKGROUND: Severe heart rhythm disturbances (SHRDs) occur regularly in cardiogenic shock (CS). Percutaneous left ventricular assist devices (pLVADs) can actively unload the left ventricle (LV), decreasing left ventricular end-diastolic pressure and wall tension, which are suspected parameters for the induction and maintenance of arrhythmias. The aim of this study was to describe effects of LV unloading on SHRD. METHOD: In the Dresden Impella Registry, 97 patients received an Impella CP in refractory CS. Of them, 19 had SHRDs, which were not stopped by common therapeutic strategies such as electrical defibrillation or antiarrhythmic drugs. They were only stopped after implantation of a micro-axial heart pump. This phenomenon was referred to as heart rhythm stabilisation (HRS). Clinical outcome and laboratory parameters were assessed and risk factors for the occurrence of HRS were identified. RESULTS: All 19 patients with refractory SHRD terminated immediately into a stable heart rhythm after insertion of the micro-axial heart pump. In 37% no additional defibrillation was needed. Of the patients with HRS, CS was mostly caused by myocardial infarction (68%). Resuscitation before pLVAD was performed in 89% for more than 30 minutes. Patients with HRS were resuscitated more frequently and for a longer duration than patients without HRS. After HRS, the serum lactate and norepinephrine dosage decreased in the first 12 hours, whereas left ventricular ejection fraction increased by 95%. CONCLUSIONS: Left ventricular unloading in patients with CS seems to be an option for treating patients with sustained life-threatening tachycardia, who are refractory to common treatment.

Paraneoplastic Syndrome and SARS-CoV-2-Incremental Effect of 2 Thrombogenic Conditions?

We present the case of a patient with a nonbacterial thrombotic aortic valve endocarditis experiencing severe thromboembolic complications and an acute right internal carotid artery occlusion in the context of a paraneoplastic syndrome and an asymptomatic severe acute respiratory syndrome coronavirus-2 infection, despite treatment with different and overlapping anticoagulant medications. Patients with increased thrombogenicity due to an underlying disease might be at increased risk for thrombotic events during a severe acute respiratory syndrome coronavirus-2 infection.

Nous présentons le cas d'un patient atteint d'endocardite thrombotique non bactérienne de la valve aortique et présentant des complications thromboemboliques graves et une occlusion aiguë de la carotide interne droite dans le contexte d'un syndrome paranéoplasique et d'une infection à coronavirus du syndrome respiratoire aigu sévère 2 (SRAS-CoV-2) asymptomatique, malgré différentes anticoagulothérapies se chevauchant. Les patients présentant une thrombogénicité accrue en raison d'une affection sous-jacente pourraient courir un plus grand risque d'événement thrombotique en cas d'infection à SRAS-CoV-2.

Influence of caveolin-1 and endothelial nitric oxide synthase on adventitial inflammation in aortic transplants.

BACKGROUND: Restenosis after endovascular interventions is a clinically relevant process that is directly associated with increased morbidity. Thereby, an increased migration and proliferation of vascular smooth muscle cells (VSMCs) is mainly responsible for recurrent lumen narrowing. Previously, we showed that caveolin­1 (Cav­1) and endothelial nitric oxide synthase (eNOS) were directly involved in neointimal proliferation. AIMS: In the current study, we investigated the impact of Cav­1 and eNOS on adventitial processes in a murine model. METHODS: Denuded aortas from C57Bl6n (wild­type [WT]), Cav­1-/, eNOS-/, and Cav­1-//eNOS-/ mice were transplanted into common carotid arteries of WT mice. The explantation was performed after 6 weeks, followed by Elastica van Gieson staining and immunohistochemistry. RESULTS: The Cav­1-/ and the eNOS-/ aortas showed an increase in the adventitial content of macrophages, whereas their combined knockout did not lead to additive effects. Differences were observed despite the same acceptor, suggesting the local origin of inflammatory cells. Furthermore, the WT transplants exhibited the highest content of vascular endothelial growth factor A (VEGF­A) despite the lowest macrophage content. In contrast, the knockout aortas showed a decreased content of VEGF­A as well as decreased expression of α-smooth muscle actin (α-­SMA) in the tunica media, suggesting induced VSMC migration. Moreover, the WT aortas exhibited increased neovessel formation. CONCLUSIONS: Cav­1 and eNOS inhibit adventitial macrophage­derived inflammation and modulate its cellular function. The knockout of Cav­1 and eNOS leads to a decreased expression of VEGF-A, with decreased neovessel formation and increased migration of VSMCs, which promote a proatherogenic phenotype.

Left Ventricular Torsion　- A New Echocardiographic Prognosticator in Patients With Non-Ischemic Dilated Cardiomyopathy.

BACKGROUND: Left ventricular (LV) torsion is a key parameter in cardiac function and predicts functional capacity (FC) more appropriately than LV ejection fraction (EF). We sought to investigate LV torsion as a marker of hospitalization for worsening heart failure (HF) in non-ischemic dilated cardiomyopathy (DCM) patients. Methods and Results: The 91 outpatients with newly diagnosed DCM (53±13 years, 20% female) were evaluated with 3D speckle-tracking imaging and followed up for 12 months; 43 healthy sex- and age-matched volunteers served as controls. LV torsion, LVEF, right ventricular function, LV global longitudinal (GLS) and circumferential (GCS) strain values, peak oxygen uptake (peak V̇O2) from FC and B-type natriuretic peptide levels were measured at baseline. Peak V̇O2correlated successively with LV torsion, diastolic filling and GCS (r=0.70, -0.52 and -0.41, P<0.01) disclosing the central role of LV torsion. During follow-up (median 272 days), 24 (26%) cardiac events occurred. A reduced LV torsion (<0.59 degrees/cm) predicted cardiac events similar to a reduced peak V̇O2(<19 mL/kg/min) (unadjusted hazard ratio 6.41 and 5.90, P<0.001). LV torsion provided a significant incremental value over right ventricular function and peak V̇O2(C-index: 0.85, P=0.02). CONCLUSIONS: The results demonstrated a clear relation between LV torsion and disease severity, suggesting that LV torsion has additional prognostic relevance in DCM patients.

Repetitive squatting exercise as a diagnostic predictor in patients with dilated cardiomyopathy.

Objectives: Non-ischaemic dilated cardiomyopathy (DCM) is characterised by a highly variable disease progression. Stress echocardiography and cardiopulmonary exercise testing (CPET) are beneficial in risk assessment, but are labour intensive. Repetitive squatting and standing without weights is a simple exercise (EX). The aim of this study was to investigate the prognostic role of left ventricular (LV) contractile recruitment (CR) after a simple EX of repetitive squatting through three-dimensional (3D) echocardiography. Methods: Patients with DCM (LV ejection fraction (EF)<50%, n=68) and age-matched healthy volunteers (n=25) received a 3D echocardiographic evaluation of LV EF before and after 30 repetitions of squatting-standing EX. CR was defined by the change of LV EF (Δ>4%). Patients were followed up prospectively (2 years) for cardiac death and deteriorating heart failure. Results: During follow-up, 14 cardiac events occurred (21%) with six deaths and eight severe heart failure deteriorations. A poor CR after squatting EX differentiated DCM patients with cardiac events during follow-up as accurately as a reduced peak oxygen consumption (peak VO 2<20 mL/kg/min) (sensitivity: 0.97 and 0.95). Both had a significant incremental diagnostic value over clinical (age, dyspnoea and natriuretic peptide level) or resting echocardiographic parameters (E/E' ratio, LV EF and end-diastolic LV volume) to predict cardiac events (global χ2: 16.0 vs 5.3; 19.5 vs 6.1; P<0.01 for all). Conclusions: The presence of LV CR after EX of repetitive squatting without weights can stratify risk and predict cardiac events in patients with DCM as correct as CPET.

Comparison of diverse platelet activation markers as indicators for left atrial thrombus in atrial fibrillation.

Atrial fibrillation (AF) is well known for being a major risk factor of thromboembolic stroke. We could recently demonstrate an association of monocyte-platelet aggregates (MPAs) with the degree of thrombogenicity in patients with AF. This study investigated platelet activation markers, as potential biomarkers for the presence of left atrial (LA) thrombus in patients with AF. One hundred and eight patients with symptomatic AF underwent transesophageal echocardiography (TEE) before scheduled cardioversion or pulmonary vein isolation. In order to determine the content of MPAs by flow-cytometric quantification analyses, blood was drawn on the day of TEE. The soluble CD40 Ligand (sCD40L) and soluble P-selectin (sP-selectin) were obtained by Cytometric Bead Arrays (CBA). D-dimer levels were detected by quantitative immunological determination of fibrin degradation products. Clinical, laboratory, and echocardiographic standard parameters were obtained from all patients, including the determination of the flow in the left atrial appendage (LAA). Patients with detected LA thrombus (n = 28) compared with patients without thrombus (n = 80) showed an increased number of common risk factors, such as age, diabetes, heart failure, and coronary artery disease (CAD). The presence of LA thrombus was associated with significantly increased levels of MPAs (147 ± 12 vs. 304 ± 29 per µl; p < 0.00), sCD40L (106.3 ± 31.0 vs. 33.5 ± 2.1 pg/ml, p = 0.027), and D-dimer (0.13 ± 0.02 vs. 0.69 ± 0.21 mg FEU/l, p = 0.015). In contrast, sP-selectin showed no association with LA thrombus. A multivariate regression analysis showed that MPAs, sCD40L as well as D-dimers were independent indicators for the existence of LA thrombus. MPAs above 170 cells/µl indicated LA thrombus with a high sensitivity of 93% and a specificity of 73% (OR 62, 95% CI. 6.9-557.2, p < 0.001) in patients with AF, whereas the D-dimer lost their quality as independent indicator by using the conventional cut-off of 0.5 mg/l within the regression analysis. MPAs, as well as the D-dimer, correlated significantly negatively with the flow in the LAA measured during TEE. The content of MPAs, sCD40L, and D-dimer, but not sP-selectin showed an increased dependence on LA thrombus in patients with AF. In our study group, MPAs showed the best diagnostic test accuracy of the compared platelet markers. The different results of the examined platelet activation markers could be an indication of diverse mechanisms of LA thrombus in AF. Further studies should evaluate whether determination of MPAs in clinical routine may suffice to indicate the presence of LA thrombus in patients with AF.

Reversal of the platelet inhibitory effect of the P2Y12 inhibitors clopidogrel, prasugrel, and ticagrelor in vitro: a new approach to an old issue.

AIM: Platelet transfusion is an effective option to reverse platelet inhibition in thienopyridine-treated patients suffering from bleedings or requiring urgent surgery. However, in ticagrelor-treated patients, the previous studies revealed significant clinical effects to platelet rich plasma (PRP) but poor response to pooled platelets (PP) as used in clinical routine. The aim of this study was to elucidate a potential pathomechanism to explain the poor response of ticagrelor to PP. METHODS AND RESULTS: From 79 whole blood samples of patients treated with ticagrelor, prasugrel, or clopidogrel, the PRI-VASP was determined before and after in vitro platelet supplementation of PP or PRP at increasing concentrations. Compared to prasugrel- and clopidogrel-treated patients, the PRI-VASP of ticagrelor-treated patients showed no significant increase after in vitro administration of PP. PRI-VASP was performed in ticagrelor-treated samples after in vitro addition of 1: centrifuged PRP platelets resuspended in PP buffer, 2: PP with human serum, 3: human serum alone. Surprisingly, PP with human serum or human serum alone were able to significantly increase PRI-VASP in samples of ticagrelor-treated patients (11.7 ± 10.9 â†’ 61.3 ± 10.9%, p = 0.006; 11.7 ± 10.9 â†’ 54.1 ± 2.7%, p < 0.001). This effect could also be shown using human albumin (18.9 ± 5.1% â†’ 80 g/l human albumin: 48.1 ± 8.3%, p < 0.001). CONCLUSION: The present study demonstrates that addition of human serum and human albumin alone is able to reverse the ticagrelor effects in vitro and supports our novel hypothesis of the importance of proteins in reversing the effects of ticagrelor by binding active ticagrelor.

Three-Dimensional Left Ventricular Torsion in Patients With Dilated Cardiomyopathy　- A Marker of Disease Severity.

BACKGROUND: LV twist has a key role in maintaining left ventricular (LV) contractility during exercise. The purpose of this study was to investigate LV torsion instead of twist as a surrogate marker of peak oxygen uptake (peak V̇O2) assessed by cardiopulmonary exercise testing (CPET) in patients with non-ischemic dilated cardiomyopathy (DCM).Methods and Results:We evaluated 45 outpatients with DCM (50±12 years, 24% females) with 3D speckle-tracking electrocardiography prior to CPET. LV torsion, LV ejection fraction (EF), LV diastolic function, LV global longitudinal (GLS) and circumferential (GCS) strain were quantified. A reduced functional capacity (FC) was defined as a peak V̇O2<20 mL/kg/min. LV torsion correlated most strongly with peak V̇O2(r=0.76, P<0.001). LV torsion instead of twist was an independent predictor of peak V̇O2(B: 0.59 to 0.71, P<0.001) in multivariable analyses. Impaired LV torsion <0.61 degrees/cm was able to predict a reduced FC with higher sensitivity and specificity (0.91 and 0.81; area under the curve (AUC): 0.88, P<0.001) than LV EF, GLS or GCS (AUC 0.64, 0.63 and 0.66; P<0.05 for differences in AUC). CONCLUSIONS: Peak V̇O2correlated more strongly with LV torsion than with LV diastolic function, LV EF, GLS or GCS. LV torsion had high accuracy in identifying patients with a reduced FC.

Atheroprotective role of Caveolin-1 and eNOS in an innovative transplantation model is mainly mediated by local effects.

Endothelial dysfunction is crucial in the initiation of atherosclerosis, which is associated with a lack of nitric oxide. The endothelial NO synthase (eNOS) is responsible for constitutive synthesis of NO and inhibited by caveolin-1 (Cav1). In the current study, we examined the influence on intima formation through single and combined deletion of eNOS and Cav1 with a focus on differentiation of local and systemic effects. A sex-mismatch transplantation of denudated aortae from female C57BL/6n (WT), Cav1-/-, eNOS-/- and Cav1-/-/eNOS-/- (C/e--/--) mice in common carotid artery of male WT mice was performed. After six weeks on Western-type diet, the aortae were explanted and intimal lesions were quantified by determining the intima-media-ratio (IMR). Significantly larger plaques were observed in all knockout mice compared to WT. The highest IMR was detected in Cav1-/- arteries associated with an increased expression of α-smooth muscle actin (αSMA) and the proliferating cell nuclear antigen (PCNA). Both were reduced in aortae from C/e--/--. Galectin-3 (Gal3) immunostaining revealed only small infiltrations of macrophages. Systemic cell invasion was detected by Y chromosome fluorescence in situ hybridization (Y-FISH), which showed only small numbers of systemic cells and no differences between the genotypes. Loss of Cav1 increased vascular lesion by enhancing neointimal proliferation. The combined loss of Cav1 and eNOS, compared to Cav1-/-, lowered intima formation, suggesting an increasing effect of eNOS in the absence of Cav1 on vascular lesion. Furthermore, these effects seem to be mediated by local cells rather than by systemically invaded ones.

Regulation of endothelial migration and proliferation by ephrin-A1.

Endothelial migration and proliferation are fundamental processes in angiogenesis and wound healing of injured or inflamed vessels. The present study aimed to investigate the regulation of the Eph/ephrin-system during endothelial proliferation and the impact of the ligand ephrin-A1 on proliferation and migration of human umbilical venous (HUVEC) and arterial endothelial cells (HUAEC). Endothelial cells that underwent contact inhibition showed a massive induction of ephrin-A1. In contrast, an injury to a confluent endothelial layer, associated with induction of migration and proliferation, showed reduced ephrin-A1 levels. In addition, reducing ephrin-A1 expression by siRNA led to increased proliferation, whereas the overexpression of ephrin-A1 led to decreased proliferative activity. Due to the fact that wound healing is a combination of proliferation and migration, migration was investigated in detail. First, classical wound-healing assays showed increased wound closure in both ephrin-A1 silenced and overexpressing cells. Live-cell imaging enlightened the underlying differences. Silencing of ephrin-A1 led to a faster but more disorientated migration. In contrast, ephrin-A1 overexpression did not influence velocity of the cells, but the migration was more directed in comparison to the controls. Additional analysis of EphA2-silenced cells showed similar results in terms of proliferation and migration compared to ephrin-A1 silenced cells. Detailed analysis of EphA2 phosphorylation on ligand-dependent phospho-site (Y588) and autonomous activation site (S897) revealed a distinct phosphorylation pattern. Furthermore, the endothelial cells ceased to migrate when they came in contact with an ephrin-A1 coated surface. Using a baculoviral-mediated expression system, ephrin-A1 silencing and overexpression was shown to modulate the formation of focal adhesions. This implicates that ephrin-A1 is involved in changes of the actin cytoskeleton which explains the alterations in migratory actions, at least in part. In conclusion, ephrin-A1 expression is regulated by cellular density and is itself a critical determinant of endothelial proliferation. According to current knowledge, ephrin-A1 seems to be remarkably involved in elementary processes of endothelial migration like cellular polarization, migratory direction and speed. These data support the notion that ephrin-A1 plays a pivotal role in basal mechanisms of re-endothelialization.

EphrinB2/EphA4-mediated activation of endothelial cells increases monocyte adhesion.

The membrane anchored ligand ephrinB2 belongs to the broad Eph/ephrin system and is able to activate different Eph receptors. The Eph receptors belong to the huge group of receptor-tyrosine kinases. Eph receptors as well as their corresponding ephrin ligands are cell-membrane attached proteins. Therefore, direct cell-cell contact is essentially for interaction. It is known that ephrinB2 plays a pivotal role in developmental and in tumour angiogenesis. Previous studies point to a crucial role of the EphA4-receptor in the process of monocyte adhesion. Since ephrinB2 is known as an interaction partner of EphA4, the aim of the present study was to investigate a possible interplay of EphA4-receptor with ephrinB2 during monocyte adhesion to the endothelium. As verified by bulk adhesion assays and atomic-force microscopy based single-cell force spectroscopy, temporary stimulation of endothelial cells from different sources with the soluble ligand ephrinB2 increased monocyte adhesion to endothelial cells. The proadhesive effect of ephrinB2 was independent of an active transcription, but is mediated via the Rho signaling pathway with subsequent modulation of the actin cytoskeleton. Furthermore, ephrinB2 mediated its impact on monocyte adhesion via the receptor EphA4 as shown by siRNA-mediated silencing. Interestingly, ephrinB2 was induced by TNF-α treatment. Silencing of ephrinB2 led to a lowering of the TNF-α mediated monocyte adhesion to endothelial cells. Furthermore, immunohistochemical staining of human atherosclerotic plaque revealed expression of ephrinB2 in macrophages. The results of the present study point to a crucial role of ephrinB2 induced EphA4 forward signaling in the context of monocyte adhesion to endothelial cells. This transcription-independent effect is mediated by Rho signaling induced actin-filament polymerization.

TNF-α-mediated adhesion of monocytes to endothelial cells-The role of ephrinA1.

The ligand ephrin A1 is more often discussed to play a role in the development of the atherosclerotic plaque and in this context especially in the monocyte adhesion to endothelial cells. As tumor necrosis factor-α (TNF-α) is known to induce monocyte adhesion to endothelium and ephrin A1 expression, the present study focuses on the involvement of ephrin A1 in TNF-α-mediated monocyte adhesion. The analysis of different members of the Eph/ephrin system in TNF-α-treated human umbilical vein endothelial cells (HUVEC) revealed that especially ephrinA1 was found to be highly regulated by TNF-α compared to other members of the Eph family. This effect is also present in arterial endothelial cells from the umbilical artery and from the coronary artery. This regulation is dependent on NFκB-activation as shown by the expression of a constitutive-active IκB-mutant. By using siRNA-mediated silencing and adenoviral overexpression of ephrinA1 in HUVEC, the involvement of ephrinA1 in the TNF-α triggered monocyte adhesion to endothelial cells could be demonstrated. In addition, these results could be verified by quantitative adhesion measurement using atomic force microscopy-based single-cell force spectroscopy and under flow conditions. Furthermore, this effect is mediated via the EphA4 receptor. EphrinA1 does not influence the mRNA or protein expression of the adhesion receptors VCAM-1 and ICAM-1 in endothelial cells. However, the surface presentation of these adhesion receptors is modulated in an ephrinA1-dependent manner. In conclusion, these data demonstrate that ephrinA1 plays an important role in the TNF-α-mediated adhesion of monocytes to endothelial cells, which might be of great importance in the context of atherosclerosis.