Costantina Manes

Mechanisms underlying adverse effects of HDL on eNOS-activating pathways in patients with coronary artery disease

Therapies that raise levels of HDL, which is thought to exert atheroprotective effects via effects on endothelium, are being examined for the treatment or prevention of coronary artery disease (CAD). However, the endothelial effects of HDL are highly heterogeneous, and the impact of HDL of patients with CAD on the activation of endothelial eNOS and eNOS-dependent pathways is unknown. Here we have demonstrated that, in contrast to HDL from healthy subjects, HDL from patients with stable CAD or an acute coronary syndrome (HDLCAD) does not have endothelial antiinflammatory effects and does not stimulate endothelial repair because it fails to induce endothelial NO production. Mechanistically, this was because HDLCAD activated endothelial lectin-like oxidized LDL receptor 1 (LOX-1), triggering endothelial PKCβII activation, which in turn inhibited eNOS-activating pathways and eNOS-dependent NO production. We then identified reduced HDL-associated paraoxonase 1 (PON1) activity as one molecular mechanism leading to the generation of HDL with endothelial PKCβII-activating properties, at least in part due to increased formation of malondialdehyde in HDL. Taken together, our data indicate that in patients with CAD, HDL gains endothelial LOX-1- and thereby PKCβII-activating properties due to reduced HDL-associated PON1 activity, and that this leads to inhibition of eNOS-activation and the subsequent loss of the endothelial antiinflammatory and endothelial repair-stimulating effects of HDL.

Endothelial-Vasoprotective Effects of High-Density Lipoprotein Are Impaired in Patients With Type 2 Diabetes Mellitus but Are Improved After Extended-Release Niacin Therapy

Background— High-density lipoprotein (HDL)–raising therapies are currently under intense evaluation, but the effects of HDL may be highly heterogeneous. We therefore compared the endothelial effects of HDL from healthy subjects and from patients with type 2 diabetes mellitus and low HDL (meeting the criteria for metabolic syndrome), who are frequently considered for HDL-raising therapies. Moreover, in diabetic patients, we examined the impact of extended-release (ER) niacin therapy on the endothelial effects of HDL. Methods and Results— HDL was isolated from healthy subjects (n=10) and patients with type 2 diabetes (n=33) by sequential ultracentrifugation. Effects of HDL on endothelial nitric oxide and superoxide production were characterized by electron spin resonance spectroscopy analysis. Effects of HDL on endothelium-dependent vasodilation and early endothelial progenitor cell–mediated endothelial repair were examined. Patients with diabetes were randomized to a 3-month therapy with ER niacin (1500 mg/d) or placebo, and endothelial effects of HDL were characterized. HDL from healthy subjects stimulated endothelial nitric oxide production, reduced endothelial oxidant stress, and improved endothelium-dependent vasodilation and early endothelial progenitor cell–mediated endothelial repair. In contrast, these beneficial endothelial effects of HDL were not observed in HDL from diabetic patients, which suggests markedly impaired endothelial-protective properties of HDL. ER niacin therapy improved the capacity of HDL to stimulate endothelial nitric oxide, to reduce superoxide production, and to promote endothelial progenitor cell–mediated endothelial repair. Further measurements suggested increased lipid oxidation of HDL in diabetic patients, and a reduction after ER niacin therapy. Conclusions— HDL from patients with type 2 diabetes mellitus and metabolic syndrome has substantially impaired endothelial-protective effects compared with HDL from healthy subjects. ER niacin therapy not only increases HDL plasma levels but markedly improves endothelial-protective functions of HDL in these patients, which is potentially more important. Clinical Trial Registration— clinicaltrials.gov. Identifier: NCT00346970.

Critical Role of the NAD(P)H Oxidase Subunit p47phox for Left Ventricular Remodeling/Dysfunction and Survival After Myocardial Infarction

Accumulating evidence suggests a critical role of increased reactive oxygen species production for left ventricular (LV) remodeling and dysfunction after myocardial infarction (MI). An increased myocardial activity of the NAD(P)H oxidase, a major oxidant enzyme system, has been observed in human heart failure; however, the role of the NAD(P)H oxidase for LV remodeling and dysfunction after MI remains to be determined. MI was induced in wild-type (WT) mice (n=46) and mice lacking the cytosolic NAD(P)H oxidase component p47phox (p47phox−/− mice) (n=32). Infarct size was similar among the groups. NAD(P)H oxidase activity was markedly increased in remote LV myocardium of WT mice after MI as compared with sham-operated mice (83±8 versus 16.7±3.5 nmol of O2− ·&mgr;g−1·min−1; P<0.01) but not in p47phox−/− mice after MI (13.5±3.6 versus 15.5±3.5 nmol of O2− ·&mgr;g−1·min−1), as assessed by electron-spin resonance spectroscopy using the spin probe CP-H. Furthermore, increased myocardial xanthine oxidase activity was observed in WT, but not in p47phox−/− mice after MI, suggesting NAD(P)H oxidase-dependent xanthine oxidase activation. Myocardial reactive oxygen species production was increased in WT mice, but not in p47phox−/− mice, after MI. LV cavity dilatation and dysfunction 4 weeks after MI were markedly attenuated in p47phox−/− mice as compared with WT mice, as assessed by echocardiography (LV end-diastolic diameter: 4.5±0.2 versus 6.3±0.3 mm, P<0.01; LV ejection fraction, 35.8±2.5 versus 22.6±4.4%, P<0.05). Furthermore, cardiomyocyte hypertrophy, apoptosis, and interstitial fibrosis were substantially reduced in p47phox−/− mice as compared with WT mice. Importantly, the survival rate was markedly higher in p47phox−/− mice as compared with WT mice after MI (72% versus 48%; P<0.05). These results suggest a pivotal role of NAD(P)H oxidase activation and its subunit p47phox for LV remodeling/dysfunction and survival after MI. The NAD(P)H oxidase system represents therefore a potential novel therapeutic target to prevent cardiac failure after MI.

Nebivolol exerts beneficial effects on endothelial function, early endothelial progenitor cells, myocardial neovascularization, and left ventricular dysfunction early after myocardial infarction beyond conventional β1-blockade.

OBJECTIVES The aim of this study was to investigate whether nebivolol has added effects on left ventricular (LV) dysfunction and remodeling early after myocardial infarction (MI) beyond its β₁-receptor-blocking properties. BACKGROUND Nebivolol is a third-generation selective β₁-adrenoreceptor antagonist that stimulates endothelial cell nitric oxide (NO) production and prevents vascular reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation. Both endothelial NO synthase-derived NO production and NADPH oxidase activation are critical modulators of LV dysfunction early after MI. METHODS Mice with extensive anterior MI (n = 90) were randomized to treatment with nebivolol (10 mg/kg/day), metoprolol-succinate (20 mg/kg/day), or placebo for 30 days starting on day 1 after surgery. RESULTS Infarct size was similar among the groups. Both β₁-adrenergic receptor antagonists caused a similar decrease in heart rate. Nebivolol therapy improved endothelium-dependent vasorelaxation and increased early endothelial progenitor cells 4 weeks after MI compared with metoprolol and placebo. Nebivolol, but not metoprolol, inhibited cardiac NADPH oxidase activation after MI, as detected by electron spin resonance spectroscopy analysis. Importantly, nebivolol, but not metoprolol, improved LV dysfunction 4 weeks after MI (LV ejection fraction: nebivolol vs. metoprolol vs. placebo: 32 ± 4% vs. 17 ± 6% vs. 19 ± 4%; nebivolol vs. metoprolol: p < 0.05) and was associated with improved survival 4 weeks post-MI compared with placebo. Nebivolol had a significantly more pronounced inhibitory effect on cardiomyocyte hypertrophy after MI compared with metoprolol. CONCLUSIONS Nebivolol improves LV dysfunction and survival early after MI likely beyond the effects provided by conventional β₁-receptor blockade. Nebivolol induced effects on NO-mediated endothelial function, early endothelial progenitor cells and inhibition of myocardial NADPH oxidase likely contribute to these beneficial effects of nebivolol early after MI.

Loss of AngiomiR-126 and 130a in Angiogenic Early Outgrowth Cells From Patients With Chronic Heart Failure Role for Impaired In Vivo Neovascularization and Cardiac Repair Capacity

Background— MicroRNAs are key regulators of angiogenic processes. Administration of angiogenic early outgrowth cells (EOCs) or CD34+ cells has been suggested to improve cardiac function after ischemic injury, in particular by promoting neovascularization. The present study therefore examines regulation of angiomiRs, microRNAs involved in angiogenesis, in angiogenic EOCs and circulating CD34+ cells from patients with chronic heart failure (CHF) and the role for their cardiac repair capacity. Methods and Results— Angiogenic EOCs and CD34+ cells were isolated from patients with CHF caused by ischemic cardiomyopathy (n=45) and healthy subjects (n=35). In flow cytometry analyses, angiogenic EOCs were largely myeloid and positive for alternatively activated M2 macrophage markers. In vivo cardiac neovascularization and functional repair capacity were examined after transplantation into nude mice with myocardial infarction. Cardiac transplantation of angiogenic EOCs from healthy subjects markedly increased neovascularization and improved cardiac function, whereas no such effect was observed after transplantation of angiogenic EOCs from patients with CHF. Real-time polymerase chain reaction analysis of 14 candidate angiomiRs, expressed in angiogenic EOCs, revealed a pronounced loss of angiomiR-126 and -130a in angiogenic EOCs from patients with CHF that was also observed in circulating CD34+ cells. Anti–miR-126 transfection markedly impaired the capacity of angiogenic EOCs from healthy subjects to improve cardiac function. miR-126 mimic transfection increased the capacity of angiogenic EOCs from patients with CHF to improve cardiac neovascularization and function. Conclusions— The present study reveals a loss of angiomiR-126 and -130a in angiogenic EOCs and circulating CD34+ cells from patients with CHF. Reduced miR-126 expression was identified as a novel mechanism limiting their capacity to improve cardiac neovascularization and function that can be targeted by miR-126 mimic transfection.Background— MicroRNAs are key regulators of angiogenic processes. Administration of angiogenic early outgrowth cells (EOCs) or CD34+ cells has been suggested to improve cardiac function after ischemic injury, in particular by promoting neovascularization. The present study therefore examines regulation of angiomiRs, microRNAs involved in angiogenesis, in angiogenic EOCs and circulating CD34+ cells from patients with chronic heart failure (CHF) and the role for their cardiac repair capacity. Methods and Results— Angiogenic EOCs and CD34+ cells were isolated from patients with CHF caused by ischemic cardiomyopathy (n=45) and healthy subjects (n=35). In flow cytometry analyses, angiogenic EOCs were largely myeloid and positive for alternatively activated M2 macrophage markers. In vivo cardiac neovascularization and functional repair capacity were examined after transplantation into nude mice with myocardial infarction. Cardiac transplantation of angiogenic EOCs from healthy subjects markedly increased neovascularization and improved cardiac function, whereas no such effect was observed after transplantation of angiogenic EOCs from patients with CHF. Real-time polymerase chain reaction analysis of 14 candidate angiomiRs, expressed in angiogenic EOCs, revealed a pronounced loss of angiomiR-126 and -130a in angiogenic EOCs from patients with CHF that was also observed in circulating CD34+ cells. Anti–miR-126 transfection markedly impaired the capacity of angiogenic EOCs from healthy subjects to improve cardiac function. miR-126 mimic transfection increased the capacity of angiogenic EOCs from patients with CHF to improve cardiac neovascularization and function. Conclusions— The present study reveals a loss of angiomiR-126 and -130a in angiogenic EOCs and circulating CD34+ cells from patients with CHF. Reduced miR-126 expression was identified as a novel mechanism limiting their capacity to improve cardiac neovascularization and function that can be targeted by miR-126 mimic transfection. # Clinical Perspective {#article-title-54}

Cardiac CT and echocardiographic evaluation of peri-device flow after percutaneous left atrial appendage closure using the AMPLATZER cardiac plug device

The aim of the study was to examine frequency, size, and localization of peri‐device leaks after percutaneous left atrial appendage (LAA)‐closure with the AMPLATZER‐Cardiac‐Plug (ACP) by using a multimodal imaging approach, i.e. combined cardiac‐CT and TEE follow‐up.

Age-related normal structural and functional ventricular values in cardiac function assessed by magnetic resonance

BackgroundThe heart is subject to structural and functional changes with advancing age. However, the magnitude of cardiac age-dependent transformation has not been conclusively elucidated.MethodsThis retrospective cardiac magnetic resonance (CMR) study included 183 subjects with normal structural and functional ventricular values. End systolic volume (ESV), end diastolic volume (EDV), and ejection fraction (EF) were obtained from the left and the right ventricle in breath-hold cine CMR. Patients were classified into four age groups (20–29, 30–49, 50–69, and ≥70 years) and cardiac measurements were compared using Pearson’s rank correlation over the four different groups.ResultsWith advanced age a slight but significant decrease in ESV (r=−0.41 for both ventricles, P<0.001) and EDV (r=−0.39 for left ventricle, r=−0.35 for right ventricle, P<0.001) were observed associated with a significant increase in left (r=0.28, P<0.001) and right (r=0.27, P<0.01) ventricular EF reaching a maximal increase in EF of +8.4% (P<0.001) for the left and +6.1% (P<0.01) for the right ventricle in the oldest compared to the youngest patient group. Left ventricular myocardial mass significantly decreased over the four different age groups (P<0.05).ConclusionsThe aging process is associated with significant changes in left and right ventricular EF, ESV and EDV in subjects with no cardiac functional and structural abnormalities. These findings underline the importance of using age adapted values as standard of reference when evaluating CMR studies.