Stephan B. Felix

Cellular adhesion molecules on vascular smooth muscle cells

Several studies during the last years have shown that, in addition to endothelial cells, vascular smooth muscle cells also express the cellular adhesion molecules ICAM-1 and VCAM-1 in atherosclerosis, restenosis and transplant vasculopathy. In vitro studies have characterized stimulatory and inhibitory factors that regulate the expression of ICAM-1 and VCAM-1 on cultured smooth muscle cells. There is evidence for a role of adhesion molecules on smooth muscle cells for leukocyte accumulation and activation of mononuclear cells. Some recent data suggest that the expression of adhesion molecules on smooth muscle cells are cell cycle-dependent and influence smooth muscle cell proliferation and differentiation. Therefore, ICAM-1 and VCAM-1 on smooth muscle cells may contribute to the inflammatory reaction in the vascular wall and may actively be involved in the progression and stability of atherosclerotic plaques.

Removal of autoantibodies in dilated cardiomyopathy by immunoadsorption

Immunoadsorption with Ig-Therasorb leads to a marked decrease in serum levels of immunoglobulins including of the agonist-like anti-beta 1-adrenoceptor autoantibody found in the serum of patients with idiopathic dilated cardiomyopathy. The reduction in autoantibody levels was accompanied by an improvement of heart function and a shift to a lower NYHA state. In this disease, as in a variety of other autoimmune disorders, apheresis with Ig-Therasorb led to a rapid improvement of the clinical status and could be used in end-stage dilated cardiomyopathy (with autoantibodies) as a bridge for transplantation.

β1-Adrenoceptor gene variations: a role in idiopathic dilated cardiomyopathy?

Abstract.A substantial body of evidence suggests involvement of the human β1-adrenoceptor (β1-AR) gene in the pathophysiology of dilated cardiomyopathy (DCM), a severe heart disease of significant public health impact. β1-AR-mediated signal transduction is dramatically altered due to downregulation, resulting in an impairment of myocardial response. The important role of genetic factors in idiopathic dilated cardiomyopathy (IDCM) recently recognized, we analyzed this prime candidate gene for genetic variation in carefully selected patients and controls. In this preliminary study, 18 single nucleotide polymorphisms were observed, 17 of which were located in the N-terminal and C-terminal region of the coding exon, resulting in 7 amino acid exchanges: Ser-49–Gly, Ala-59–Ser, Gly-389–Arg, Arg-399–Cys, His-402–Arg, Thr-404–Ala, and Pro-418–Ala. These mutations resulted in 11 different β1-AR genotypes. Importantly, the genotypes carrying the Ser-49–Gly mutation in the N-terminus of the molecule in a heterozygous or homozygous form were observed significantly more frequently in the group of IDCM patients. The present results may provide a clue on the molecular mechanisms involved in IDCM, and add moreover interesting information on nature, distribution, and evolutionary aspects of sequence variation in human adrenergic receptor genes.

A1/A2 polymorphism of glycoprotein IIIa and association with excess procedural risk for coronary catheter interventions: a case-controlled study

BACKGROUND A five-fold increase in risk of stent thrombosis in carriers of A1/A2 (Leu33Pro) polymorphism of glycoprotein Illa has been described. Whether this increased procedural risk applies to other coronary interventions is unknown. We investigated the role of A1/A2 polymorphism as a putative risk factor. METHODS We genotyped 1000 consecutive patients with angiographically confirmed coronary-artery disease and 1000 controls matched for age and sex. 653 of the 1000 patients received interventions (271 coronary angioplasty, 102 directional coronary atherectomy, and 280 stenting) and were assessed for a 30-day composite endpoint of need for target-vessel revascularisation, myocardial infarction, and death. FINDINGS The composite endpoint occurred in 41 (6.3%) patients. There was no evidence that the A2 allele was associated with excess procedural risk (relative risk 1.36 [95% CI 0.70-2.70], p=0.37). Nor, in subgroup analyses, did A2 predict events that complicated coronary angioplasty (1.17 [0.40-2.70]), directional coronary atherectomy (1.50 [0.30-8.70]), or stenting (1.45 [0.60-3.50]). Neither heterozygotes (A1/A2) nor homozygotes (A2/A2) were over-represented in any subgroup, including those with acute coronary syndromes, early disease manifestation (age <40 years), and histories of myocardial infarction. INTERPRETATION A1/A2 polymorphism is not a major risk factor for 30-day adverse events that complicate coronary angioplasty, directional coronary atherectomy, or stenting. Furthermore, A1/A2 polymorphism has no apparent impact on more chronic processes such as atherogenesis of the coronary arteries.

Guided de-escalation of antiplatelet treatment in patients with acute coronary syndrome undergoing percutaneous coronary intervention (TROPICAL-ACS): A randomised, open-label, multicentre trial

BACKGROUND Current guidelines recommend potent platelet inhibition with prasugrel or ticagrelor for 12 months after an acute coronary syndrome managed with percutaneous coronary intervention (PCI). However, the greatest anti-ischaemic benefit of potent antiplatelet drugs over the less potent clopidogrel occurs early, while most excess bleeding events arise during chronic treatment. Hence, a stage-adapted treatment with potent platelet inhibition in the acute phase and de-escalation to clopidogrel in the maintenance phase could be an alternative approach. We aimed to investigate the safety and efficacy of early de-escalation of antiplatelet treatment from prasugrel to clopidogrel guided by platelet function testing (PFT). METHODS In this investigator-initiated, randomised, open-label, assessor-blinded, multicentre trial (TROPICAL-ACS) done at 33 sites in Europe, patients were enrolled if they had biomarker-positive acute coronary syndrome with successful PCI and a planned duration of dual antiplatelet treatment of 12 months. Enrolled patients were randomly assigned (1:1) using an internet-based randomisation procedure with a computer-generated block randomisation with stratification across study sites to either standard treatment with prasugrel for 12 months (control group) or a step-down regimen (1 week prasugrel followed by 1 week clopidogrel and PFT-guided maintenance therapy with clopidogrel or prasugrel from day 14 after hospital discharge; guided de-escalation group). The assessors were masked to the treatment allocation. The primary endpoint was net clinical benefit (cardiovascular death, myocardial infarction, stroke or bleeding grade 2 or higher according to Bleeding Academic Research Consortium [BARC]) criteria) 1 year after randomisation (non-inferiority hypothesis; margin of 30%). Analysis was intention to treat. This study is registered with ClinicalTrials.gov, number NCT01959451, and EudraCT, 2013-001636-22. FINDINGS Between Dec 2, 2013, and May 20, 2016, 2610 patients were assigned to study groups; 1304 to the guided de-escalation group and 1306 to the control group. The primary endpoint occurred in 95 patients (7%) in the guided de-escalation group and in 118 patients (9%) in the control group (pnon-inferiority=0·0004; hazard ratio [HR] 0·81 [95% CI 0·62-1·06], psuperiority=0·12). Despite early de-escalation, there was no increase in the combined risk of cardiovascular death, myocardial infarction, or stroke in the de-escalation group (32 patients [3%]) versus in the control group (42 patients [3%]; pnon-inferiority=0·0115). There were 64 BARC 2 or higher bleeding events (5%) in the de-escalation group versus 79 events (6%) in the control group (HR 0·82 [95% CI 0·59-1·13]; p=0·23). INTERPRETATION Guided de-escalation of antiplatelet treatment was non-inferior to standard treatment with prasugrel at 1 year after PCI in terms of net clinical benefit. Our trial shows that early de-escalation of antiplatelet treatment can be considered as an alternative approach in patients with acute coronary syndrome managed with PCI. FUNDING Klinikum der Universität München, Roche Diagnostics, Eli Lilly, and Daiichi Sankyo.

Pulmonary release and coronary and peripheral consumption of big endothelin and endothelin-1 in severe heart failure: acute effects of vasodilator therapy.

BackgroundWe investigated plasma endothelin (ET) levels in patients with congestive heart failure (CHF) during treatment for acute decompensation; we also measured imbalances in ET peptides across the pulmonary, coronary, and peripheral circulation. Methods and ResultsIn patients with severe CHF (n=21; cardiac index [CI], 1.9±0.2 L · min−1 · m−2; pulmonary capillary wedge pressure [PCWP], 31±1 mm Hg), vasodilation was achieved with the nitric oxide donor sodium nitroprusside (n=11) or with the &agr;1-antagonist urapidil (nitric oxide–independent, n=10). ET concentrations were determined from arterial blood and blood from the pulmonary artery, coronary sinus, and antecubital vein. Depending on sites of measurement, baseline big ET and ET-1 levels were, respectively, 12 to 16 times and 5 to 11 times higher than in controls (n=11), and 4 to 6 times and 2 to 3 times higher than in patients with moderate CHF (n=10; CI, 2.7±0.3 L · min−1 · m−2; PCWP, 14±2 mm Hg). Patients with severe CHF demonstrated pulmonary net release and coronary and peripheral net consumption of both peptides (ie, arterial levels [big ET, 7.3±1.3 pmol/L; ET-1, 1.8±0.1 pmol/L] were higher than levels in the pulmonary artery [6.7±1.2 pmol/L; 1.3±0.1 pmol/L], coronary sinus [6.4±1.0 pmol/L; 1.4±0.1 pmol/L], and antecubital vein [6.6±1.1 pmol/L; 1.3±0.1 pmol/L]). In these patients, sodium nitroprusside (SNP) and urapidil resulted in comparable hemodynamic improvement after 6 hours (CI: SNP, 63±2%; urapidil, 72±3%; PCWP: SNP, −50±2%; urapidil, −47±2%) and a maximum decrease in ET peptides by >50%. After 3 hours, pulmonary net release and coronary and peripheral net consumption were no longer detectable. ConclusionsIn patients with severe CHF, the lungs act as a producer and the heart and the periphery act as consumers of elevated circulating ETs. Short-term vasodilator therapy decreases ETs and restores their pulmonary, coronary, and peripheral balance.

Adrenomedullin and myocardial contractility in the rat.

The effects of adrenomedullin in the regulation of myocardial contractility were investigated in the rat. In papillary muscles (n=6), adrenomedullin (0.1 to 10 nM) failed to show contractile effects. NO (nitric oxide) synthase inhibition with N(G)-nitro-L-arginine (L-NOARG) did not unmask any inotropic effect of adrenomedullin. The positive inotropic effect of isoprenaline (0. 01 nM to 10 microM) was identical after adrenomedullin, after L-NOARG, and after L-NOARG plus adrenomedullin (n=6 each). In field-stimulated rat ventricular myocytes, adrenomedullin (1, 10, and 100 nM; n=4 each) had impact neither on cell shortening nor on Ca(2+) transients. In isolated constant-flow perfused hearts (7.3+/-0.3 ml/min), adrenomedullin (1 nM, n=9; 10 nM, n=7) induced significant coronary vasodilation (-28%, -50%). In conclusion, adrenomedullin is a potent coronary vasodilator, but has no significant effects on myocardial contractility in the rat.

Release of a stable cardiodepressant mediator after myocardial ischaemia during reperfusion

OBJECTIVE The aim of this study was to investigate whether cardiodepressant mediators are released after myocardial ischaemia during reperfusion. METHODS Using a double heart model, the effect of the reoxygenated coronary effluent of an isolated guinea pig heart on a sequentially perfused second heart was studied under control conditions and after 10 min ischaemia of the first heart. Investigation of the modulating role of known autacoids took place by using free radical scavengers, an NO synthase inhibitor and adenosine receptor antagonists. In order to identify the chemical nature of cardiac metabolites, the coronary effluent was also subjected to different chemical treatment modes. RESULTS No haemodynamic changes were observed during sequential perfusion under control conditions. After 10 min of global ischaemia in heart I, a marked decrease in LVP (-22%), LVdP/dtmax (-43%), LVdP/dtmin (-41%) and coronary perfusion pressure (-25%) was measured in heart II during sequential perfusion. The negative inotropic effect was rapid in onset and reversible within 5 min; free radicals, nitric oxide and adenosine were not involved. Storage of the coronary effluent of the first heart up to 24 h, heating, or protease treatment did not modify its cardiodepressant effects on the second sequentially perfused heart. CONCLUSIONS These results suggest the release--from an isolated heart after ischaemia during reperfusion--of a cardiodepressant mediator which induces a potent reversible negative inotropic effect on a sequentially perfused heart. The mediator is stable and in all probability not a protein.

Sphingosine-1-phosphate induces thrombin receptor PAR-4 expression to enhance cell migration and COX-2 formation in human monocytes

Thrombin is not only a central factor in blood coagulation but also stimulates inflammatory processes, including monocyte responses, via activation of PARs. The signaling lipid S1P is a major determinant of monocyte function. Here, we established an interaction between S1P and human monocyte responses to thrombin. S1P induced PAR‐1 and PAR‐4 mRNA and total protein expression in human monocytes and U937 cells in a concentration (0.1–10 μM)‐ and time (1–24 h)‐dependent manner, respectively. However, only PAR‐4 cell‐surface expression was increased significantly by S1P, whereas PAR‐1 remained unaffected. This response was associated with activation of the Akt, Erk, and p38 pathway and induction of COX‐2 but not COX‐1. PAR‐4‐mediated induction of COX‐2 was prevented by the PI3K inhibitor LY (10 μM). Preincubation of human monocytes with S1P (1 μM; 16 h) resulted in an enhanced chemotaxis toward thrombin or to selective AP for PAR‐4 but not PAR‐1. Furthermore, down‐regulation of PAR‐4 transcription with siRNA attenuated the chemotactic response to thrombin and AP4. In conclusion, S1P enhances monocyte responses to thrombin via up‐regulation of PAR‐4 expression, which promotes cell migration and COX‐2 abundance. This mechanism may facilitate monocyte recruitment to sites of vessel injury and inflammation.

Cardiodepressive Mediators Are Released After Ischemia From an Isolated Heart: Role of Coronary Endothelial Cells

OBJECTIVES This study was designed to ascertain whether cardiodepressive mediators released after ischemia originate from coronary endothelial cells. BACKGROUND Endothelial cells modulate myocardial contractility under physiologic conditions. Few data are available describing the role of coronary endothelial cells on myocardial function after ischemia. METHODS Using a model of sequential perfusion of two isolated rat hearts, the effect of the reoxygenated coronary effluent of heart I was investigated on myocardial contractility of heart II. After 40 min of separate perfusion at constant flow (10 ml/min), the two hearts were perfused sequentially with (group I) or without (control group) preceding ischemia (10 min) of heart I. In groups II and III, the coronary endothelium of heart I was functionally removed by Triton X-100 or hyperkalemic infusion before global ischemia. Endothelial damage was confirmed by functional tests and electron microscopy. RESULTS Under control conditions no changes were observed in heart II during sequential perfusion. In contrast, after 10 min of ischemia in heart I, a marked reversible decrease in left ventricular pressure, left ventricular dP/dtmax and left ventricular dP/dtmin (-55%, -66% and -70%, respectively) was observed in heart II. Heart rate and coronary perfusion pressure did not change significantly. Selective endothelial damage of heart I before ischemia did not modify the negative inotropic effect observed in heart II. CONCLUSIONS Cardiodepressive mediators are released after ischemia during reperfusion from an isolated heart and induce a reversible negative inotropic effect in a sequentially perfused heart. It is unlikely that these agents are derived from the coronary endothelium.