Christian Besler

University of Zurich, Zürich, ZH, Switzerland

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Publications (34)215.4 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Thrombus formationis determined by the balance between pro- thrombotic mediators and anti-thrombotic factors.High-density lipoprotein (HDL) from healthy subjects exerts anti-thrombotic properties. Whether this is also the case for HDL from patients with stable coronary heart disease (CHD) or acute coronary syndrome (ACS) is unknown.In human aortic endothelial cells in culture,HDL (50 µg/ml) from healthy subjects (HS) inhibited thrombin-induced tissue factor (TF) expression and activity, while HDL (50 µg/ml) from CHD and ACS patients did not. Similarly, only healthy HDL increased endothelial tissue factor pathway inhibitor (TFPI) expression and tissue plasminogen activator (tPA) release, while HDL from CHD and ACS patients had no effect. Healthy HDL inhibited thrombin-induced plasminogen activator inhibitor type 1 (PAI-1) expression, while HDL from ACS patients enhanced endothelial PAI-1 expression. Inhibition of nitric oxide (NO) formation with L-NAME (100 µmol/l) abolished the anti-thrombotic effects of healthy HDL on TF, TFPI, and tPA expression. The exogenous nitric oxide donor, DETANO, mimicked the effects of healthy HDL and counterbalanced the loss of anti-thrombotic effects of HDL from CHD and ACS patients in endothelial cells. In line with this observation, healthy HDL, in contrast to HDL from CHD and ACS patients, increased endothelial NO production. In the laser-injured carotid artery of the mouse, thrombus formation was delayed in animals treated with healthy HDL compared with mice treated with vehicle or HDL from patients with CHD or ACS. In conclusion, HDL from CHD and ACS patients loses the ability of healthy HDL to suppress TF and to increase TFPI and t-PA and instead enhances PAI-1 and arterial thrombus formation.
    Thrombosis and haemostasis. 07/2014; 112(5).
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    ABSTRACT: Rationale: HDL exerts endothelial-protective effects via stimulation of endothelial cell (EC) NO production. This function is impaired in patients with cardiovascular disease. Protective effects of exercise training (ET) on endothelial function have been demonstrated Objective: This study was performed to evaluate the impact of ET on HDL-mediated protective effects and the respective molecular pathways in patients with chronic heart failure (CHF). Methods and Results: HDL was isolated from 16 healthy controls (HDLhealthy) and 16 patients with CHF-NYHA-III (HDLNYHA-IIIb) before and after ET, and 8 patients with CHF-NYHA-II (HDLNYHA-II). EC were incubated with HDL and phosphorylation of eNOS-Ser(1177), eNOS-Thr(495), PKC-ßII-Ser(660) and p70S6K-Ser(411) was evaluated. HDL-bound malondialdehyde and HDL-induced NO production by EC were quantified. Endothelial function was assessed by flow-mediated dilatation (FMD). The proteome of HDL particles was profiled by shotgun LC-MS/MS. Incubation of EC with HDLNYHA-IIIb triggered a lower stimulation of phosphorylation at eNOS-Ser(1177) and a higher phosphorylation at eNOS-Thr(495) when compared to HDLhealthy. This was associated with lower NO production of EC. In addition an elevated activation of p70S6K, PKC-ßII by HDLNYHA-IIIb, and a higher amount of malondialdehyde bound to HDLNYHA-IIIb compared to HDLhealthy was measured. In healthy individuals ET had no effect on HDL function, whereas ET of CHF-NYHA-IIIB significantly improved HDL function. A correlation between changes in HDL-induced NO production and FMD improvement by ET was evident. Conclusions: These results demonstrate that HDL-function is impaired in CHF and that ET improved the HDL-mediated vascular effects. This may be one mechanism how ET exerts beneficial effects in CHF.
    Circulation Research 09/2013; · 11.86 Impact Factor
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    ABSTRACT: Myeloperoxidase (MPO) and paraoxonase 1 (PON1) are high-density lipoprotein-associated (HDL-associated) proteins mechanistically linked to inflammation, oxidant stress, and atherosclerosis. MPO is a source of ROS during inflammation and can oxidize apolipoprotein A1 (APOA1) of HDL, impairing its atheroprotective functions. In contrast, PON1 fosters systemic antioxidant effects and promotes some of the atheroprotective properties attributed to HDL. Here, we demonstrate that MPO, PON1, and HDL bind to one another, forming a ternary complex, wherein PON1 partially inhibits MPO activity, while MPO inactivates PON1. MPO oxidizes PON1 on tyrosine 71 (Tyr71), a modified residue found in human atheroma that is critical for HDL binding and PON1 function. Acute inflammation model studies with transgenic and knockout mice for either PON1 or MPO confirmed that MPO and PON1 reciprocally modulate each other's function in vivo. Further structure and function studies identified critical contact sites between APOA1 within HDL, PON1, and MPO, and proteomics studies of HDL recovered from acute coronary syndrome (ACS) subjects revealed enhanced chlorotyrosine content, site-specific PON1 methionine oxidation, and reduced PON1 activity. HDL thus serves as a scaffold upon which MPO and PON1 interact during inflammation, whereupon PON1 binding partially inhibits MPO activity, and MPO promotes site-specific oxidative modification and impairment of PON1 and APOA1 function.
    The Journal of clinical investigation 08/2013; · 15.39 Impact Factor
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    ABSTRACT: OBJECTIVE: MicroRNAs are important intracellular regulators of gene expression, but also circulate in the blood being protected by extracellular vesicles, proteins, or high-density lipoprotein (HDL). Here, we evaluate the regulation and potential function of HDL- and low-density lipoprotein-bound miRs isolated from healthy subjects and patients with coronary artery disease.Approach and Results-HDL-bound miRs with known effects in the cardiovascular system were analyzed in HDL isolated from healthy subjects (n=10), patients with stable coronary artery disease (n=10), and patients with an acute coronary syndrome (n=10). In HDL from healthy subjects, miR-223 was detected at concentrations >10 000 copies/µg HDL, and miR-126 and miR-92a at about 3000 copies/µg HDL. Concentrations of most miRs were substantially higher in HDL as compared with low-density lipoprotein. However, HDL-bound miR-223 contributed to only 8% of the total circulating miRs. The signatures of miRs varied only slightly in HDL derived from patients with coronary artery disease. We did not observe a significant uptake of HDL-bound miRs into endothelial cells, smooth muscle cells, or peripheral blood mononuclear cells. However, patient-derived HDL transiently reduced miR expression particularly when incubated with smooth muscle and peripheral blood mononuclear cells. CONCLUSIONS: Circulating miRs are detected in HDL and to a lesser extent in low-density lipoprotein, and the miR-signatures are only slightly altered in patients with coronary artery disease. Lipoprotein-bound miRs were not efficiently delivered to endothelial, smooth muscle, and peripheral blood mononuclear cells suggesting that the lipoprotein-associated pool of miRs is not regulating the function of the studied cells in vitro.
    Arteriosclerosis Thrombosis and Vascular Biology 04/2013; · 6.34 Impact Factor
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    ABSTRACT: BACKGROUND: Endothelial dysfunction and injury are thought to play an important role in progression of coronary-artery-disease (CAD). High-density-lipoprotein from healthy subjects (HDLHealthy) has been proposed to exert endothelial anti-apoptotic effects that may represent an important anti-atherogenic property of the lipoprotein. The present study therefore aimed to compare effects of HDLCAD and HDLHealthy on activation of endothelial anti- and pro-apoptotic pathways and to determine which changes of the lipoprotein are relevant for these processes. METHODS AND RESULTS: HDL was isolated from patients with stable CAD (HDLsCAD), an acute coronary syndrome (HDLACS) and healthy subjects. HDLHealthy induced expression of the endothelial anti-apoptotic Bcl-2 protein Bcl-xL and reduced endothelial cell apoptosis in vitro and in apoE-deficient-mice in vivo. In contrast, HDLsCAD and HDLACS did not inhibit endothelial apoptosis, failed to activate endothelial Bcl-xL and stimulated endothelial pro-apoptotic pathways, in particular p38-MAPK-mediated activation of the pro-apoptotic Bcl-2-protein tBid. Endothelial anti-apoptotic effects of HDLHealthy were observed after inhibition of endothelial nitric-oxide-synthase and after delipidation, but not completely mimicked by apoA-I or reconstituted HDL, suggesting an important role of the HDL-proteome. HDL proteomics analyses and subsequent validations and functional characterizations suggested a reduced clusterin- and increased apoC-III-content of HDLsCAD and HDLACS as mechanisms leading to altered effects on endothelial apoptosis. CONCLUSIONS: The present study demonstrates for the first time that HDLCAD does not activate endothelial anti-apoptotic pathways, but rather stimulates potential endothelial pro-apoptotic pathways. HDL-proteome remodeling plays an important role for these altered functional properties of HDL. These findings provide novel insights into mechanisms leading to altered vascular effects of HDL in coronary disease.
    Circulation 01/2013; · 15.20 Impact Factor
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    ABSTRACT: 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 due to ischemic cardiomyopathy (n=45) and healthy subjects (HS; 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 (MI). Cardiac transplantation of angiogenic-EOCs from HS markedly increased neovascularization and improved cardiac function, whereas no such effect was observed after transplantation of angiogenic-EOCs from patients with CHF. RT-PCR 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 HS 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.
    Circulation 11/2012; · 15.20 Impact Factor
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    Christian Besler, Thomas F Lüscher, Ulf Landmesser
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    ABSTRACT: Low high-density lipoprotein (HDL)-cholesterol levels are associated with an increased risk of coronary artery disease (CAD) and myocardial infarction, which has triggered the hypothesis that HDL, in contrast to low-density lipoprotein (LDL), acts as an anti-atherogenic lipoprotein. Moreover, experimental studies have identified potential anti-atherogenic properties of HDL, including promotion of macrophage cholesterol efflux and direct endothelial-protective effects of HDL, such as stimulation of endothelial nitric oxide production and repair, anti-apoptotic, anti-inflammatory and anti-thrombotic properties. Studies in gene-targeted mice, however, have also indicated that increasing HDL-cholesterol plasma levels can either limit (e.g. apolipoprotein A-I) or accelerate (e.g. Scavenger receptor class B type I) atherosclerosis. Moreover, vascular effects of HDL have been observed to be heterogenous and are altered in patients with CAD or diabetes, a condition that has been termed 'HDL dysfunction'. These alterations in biological functions of HDL may need to be taken into account for HDL-targeted therapies and considering raising of HDL-cholesterol levels alone is likely not sufficient in this respect. It will therefore be important to further determine, which biological functions of HDL are critical for its anti-atherosclerotic properties, as well as how these can be measured and targeted.
    EMBO Molecular Medicine 03/2012; 4(4):251-68. · 7.80 Impact Factor
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    ABSTRACT: A marked increase in HDL notwithstanding, the cholesterol ester transfer protein (CETP) inhibitor torcetrapib was associated with an increase in all-cause mortality in the ILLUMINATE trial. As underlying mechanisms remain elusive, the present study was designed to delineate potential off-target effects of torcetrapib. Spontaneously hypertensive rats (SHRs) and Wistar-Kyoto (WKY) rats were treated with torcetrapib (100 mg/kg/day; SHR-T and WKY-T) or placebo (SHR-P and WKY-P) for 3 weeks. Blood pressure transiently increased during the first 3 days of torcetrapib administration in SHRs and returned to baseline thereafter despite continued drug administration. Acetylcholine-induced endothelium-dependent relaxations of aortic rings were markedly impaired, and endothelial nitric oxide synthase (eNOS) mRNA and protein were down-regulated after 3 weeks of torcetrapib treatment in SHR (P < 0.0001, <0.01, and <0.05, resp. vs. SHR-P). Torcetrapib reduced NO release in cultured aortic endothelial cells (P < 0.01 vs. vehicle-treated cells) and increased generation of reactive oxygen species in aortas of SHR-T (P < 0.05, vs. SHR-P). Vascular reactivity to endothelin-1 (ET-1) and aortic ET-1 tissue content were increased in SHR-T (P < 0.05 vs. SHR-P). Importantly, the ET-1 receptor A/B (ET(A/B)) antagonist bosentan normalized endothelial function in SHR-T (P < 0.05). Torcetrapib induces a sustained impairment of endothelial function, decreases eNOS mRNA, protein as well as NO release, stimulates vascular ROS and ET production, an effect that is prevented by chronic ET(A/B)-receptor blockade. These unexpected off-target effects of torcetrapib need to be ruled out in the clinical development of novel CETP inhibitors, particularly before a large patient population at increased cardiovascular risk is exposed to these compounds.
    European Heart Journal 09/2011; 33(13):1615-24. · 14.72 Impact Factor
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    ABSTRACT: 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.
    The Journal of clinical investigation 06/2011; 121(7):2693-708. · 15.39 Impact Factor
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    ABSTRACT: 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. 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. 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. 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. 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.
    Journal of the American College of Cardiology 02/2011; 57(5):601-11. · 14.09 Impact Factor
  • Atherosclerosis Supplements - ATHEROSCLER SUPPL. 01/2011; 12(1):14-14.
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    ABSTRACT: Excessive production of reactive oxygen species (ROS) contributes to progression of atherosclerosis, at least in part by causing endothelial dysfunction and inflammatory activation. The class III histone deacetylase SIRT1 has been implicated in extension of lifespan. In the vasculature,SIRT1 gain-of-function using SIRT1 overexpression or activation has been shown to improve endothelial function in mice and rats via stimulation of endothelial nitric oxide (NO) synthase (eNOS). However, the effects of SIRT1 loss-of-function on the endothelium in atherosclerosis remain to be characterized. Thus, we have investigated the endothelial effects of decreased endogenous SIRT1 in hypercholesterolemic ApoE-/- mice. We observed no difference in endothelial relaxation and eNOS (Ser1177) phosphorylation between 20-week old male atherosclerotic ApoE-/- SIRT1+/- and ApoE-/- SIRT1+/+ mice. However, SIRT1 prevented endothelial superoxide production, inhibited NF-kappaB signaling, and diminished expression of adhesion molecules. Treatment of young hypercholesterolemic ApoE-/- SIRT1+/- mice with lipopolysaccharide to boost NF-kappaB signaling led to a more pronounced endothelial expression of ICAM-1 and VCAM-1 as compared to ApoE-/- SIRT1+/+ mice. In conclusion, endogenous SIRT1 diminishes endothelial activation in ApoE-/- mice, but does not affect endothelium-dependent vasodilatation.
    Aging 06/2010; 2(6):353-60. · 4.70 Impact Factor
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    ABSTRACT: Endothelial activation, macrophage infiltration, and foam cell formation are pivotal steps in atherogenesis. Our aim in this study was to analyse the role of SIRT1, a class III deacetylase with important metabolic functions, in plaque macrophages and atherogenesis. Using partial SIRT1 deletion in atherosclerotic mice, we demonstrate that SIRT1 protects against atherosclerosis by reducing macrophage foam cell formation. Peritoneal macrophages from heterozygous SIRT1 mice accumulate more oxidized low-density lipoprotein (oxLDL), thereby promoting foam cell formation. Bone marrow-restricted SIRT1 deletion confirmed that SIRT1 function in macrophages is sufficient to decrease atherogenesis. Moreover, we show that SIRT1 reduces the uptake of oxLDL by diminishing the expression of lectin-like oxLDL receptor-1 (Lox-1) via suppression of the NF-κB signalling pathway. Our findings demonstrate protective effects of SIRT1 in atherogenesis and suggest pharmacological SIRT1 activation as a novel anti-atherosclerotic strategy by reducing macrophage foam cell formation.
    European Heart Journal 04/2010; 31(18):2301-9. · 14.72 Impact Factor
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    ABSTRACT: Reduced levels of high-density lipoprotein cholesterol (HDL) are associated with a substantially increased risk of coronary disease and cardiovascular events. Furthermore, numerous studies have suggested that HDL may exert several potentially important antiatherosclerotic and endothelial-protective effects. In particular, the promotion of reverse cholesterol transport, i.e. cholesterol efflux from lipid-loaded macrophages in atherosclerotic lesions and the subsequent cholesterol transport back to the liver, has been proposed as an anti-atherogenic effect of HDL that may promote regression of atherosclerotic lesions. Moreover, endothelial dysfunction is thought to play a critical role in development and progression of atherosclerosis and several recent studies have suggested that HDL exerts direct endothelial-protective effects, such as stimulation of endothelial production of the anti-atherogenic molecule nitric oxide, anti-oxidant, anti-inflammatory and anti-thrombotic effects. Furthermore, it has been observed that HDL may stimulate endothelial repair processes, involving mobilisation and promotion of endothelial repair capacity of endothelial progenitor cells. The relative significance of these different potential anti-atherosclerotic effects of HDL remains still unclear at present. Importantly, at the same time it has been recognized that the vascular effects of HDL may be variable, i.e. the capacity of HDL to stimulate macrophage cholesterol efflux and endothelial-protective effects may be altered in patients with inflammatory or cardiovascular disease. The further characterisation of underlying mechanisms and the identification of the clinical relevance of this "HDL dysfunction" are currently an active field of research. HDL-targeted treatment strategies are at present intensely evaluated and may lead to increased HDL plasma levels and/or HDL-stimulated anti-atherosclerotic effects. The cardiovascular protection provided by such approaches may likely depend on HDL function or quality, i.e. the anti-atherosclerotic and endothelial-protective properties of the on-treatment HDL. Currently, several HDL-raising treatment strategies are examined in clinical trials, i.e. extended-release niacin, the CETP inhibitors dalcetrapib and anacetrapib, reconstituted forms of HDL (i.e. CSL-111) or apoA-I mimetics, and some of these are already in large clinical outcome studies on top of statin therapy to determine their efficacy and safety for cardiovascular prevention.
    Current pharmaceutical design 03/2010; 16(13):1480-93. · 4.41 Impact Factor
  • Current Pharmaceutical Design - CURR PHARM DESIGN. 01/2010; 16(13):1480-1493.
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    ABSTRACT: 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. 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. 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. clinicaltrials.gov. Identifier: NCT00346970.
    Circulation 12/2009; 121(1):110-22. · 15.20 Impact Factor
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    ABSTRACT: Accelerated atherosclerosis has been described in antiphospholipid syndrome, but the vascular abnormalities and the underlying mechanisms remain unclear. To compare vascular structure and function in patients with positive antiphospholipid antibodies (aPL) with controls and to assess their relationship with paraoxonase activity. A cross-sectional study of 77 women with positive antiphospholipid antibodies from a lupus outpatient clinic in London, England (90% of the eligible population) and 77 controls matched on frequency basis for age and cardiovascular risk factors between June 2006 and April 2009. Carotid intima media thickness (CIMT), flow-mediated dilatation, pulse wave velocity, and paraoxonase activity were measured in all patients. Anti-inflammatory and antioxidant properties of high-density lipoprotein (HDL) were examined. CIMT, pulse wave velocity, flow-mediated dilatation, and paraoxonase. Women with aPL had greater CIMT and pulse wave velocity compared with controls (mean [SD], 0.75 [0.16] vs 0.64 [0.09] mm; 95% confidence interval [CI], -0.14 to -0.06; P < .001; and 9.2 [1.6] vs 8.5 [1.8] m/s; 95% CI, -1.14 to -0.06; P = .04) and lower flow-mediated dilatation (6.2% [4.1%] vs 9.6% [4.2%]; 95% CI, 2.02%-4.69%; P < .001). Paraoxonase activity was lower in women with aPL vs controls (median [interquartile range], 91.2 [64.3-105.1] vs 103.0 [80.5-111.5] micromol p-nitrophenol/L/serum/min; 95% CI, 0.004-0.007; P = .005) and was inversely associated with CIMT and pulse wave velocity in women with aPL (standardized beta coefficient = -0.4 and -0.3, respectively; P < .05 for both), but not in the control group. High-density lipoprotein from women with aPL inhibited endothelial nitric oxide production in human aortic endothelial cells, in contrast with controls. The beneficial effects of HDL from women with aPL on vascular cell adhesion molecule 1 expression, superoxide production, and monocyte adhesion following activation of human aortic endothelial cells were largely blunted. Compared with controls, women with aPL had greater functional and structural arterial abnormalities, which were associated with lower activity of paraoxonase. In patients with aPL, HDL reduced nitric oxide bioavailability and had impaired anti-inflammatory and antioxidant properties.
    JAMA The Journal of the American Medical Association 09/2009; 302(11):1210-7. · 29.98 Impact Factor
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    ABSTRACT: Low-density lipoprotein (LDL) uptake by monocyte-derived macrophages is a crucial step in foam cell formation and early atherosclerotic lesion. Increasing evidence supports the theory that activation of protein kinase Cbeta (PKCbeta) is involved in many mechanisms promoting atherosclerosis. Thus, we investigated whether inhibition of PKCbeta prevents foam cell formation. The differentiation of human primary monocytes or the monocytic THP-1 cell line into monocyte-derived macrophages was induced by phorbol 12-myristate 13-acetate (PMA; 0.1 mmol/L), a potent activator of PKC. Incubation of monocyte-derived macrophages with DiI-modified LDL (acetylated LDL and oxidized LDL, 10 mug/mL) led to lipoprotein uptake. Interestingly enough, the nonselective inhibitor of PKCbeta(1) and PKCbeta(2), LY379196 (5x10(-7) to 10(-5) mol/L), blunted LDL uptake in monocyte-derived macrophages as shown by flow cytometry. Specific siRNA-mediated knockdown of PKCbeta exerted a similar effect. Furthermore, PMA alone and in the presence of modified LDL induced scavenger receptor A mRNA and protein expression, which was abolished by LY379196. CGP53353, a selective inhibitor of PKCbeta(2), did not affect LDL uptake, nor did it prevent scavenger receptor A upregulation. Incubation of monocyte-derived macrophages with PMA/LDL increased PKCbeta(1) phosphorylation at the Thr-642 residue, which was blunted by LY379196. However, the expression of CD68, a marker of activated macrophages, was not affected by LY379196. Moreover, LY379196 did not affect lipopolysaccharide-induced CD14 degradation, tumor necrosis factor-alpha release, or superoxide anion production, ruling out any effect of PKCbeta inhibition on innate immunity. Nonspecific inhibition of PKCbeta prevents LDL uptake in macrophages. These findings suggest that PKCbeta inhibitors may represent a novel class of antiatherosclerotic drugs.
    Circulation 12/2008; 118(21):2174-82. · 15.20 Impact Factor
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    ABSTRACT: Endothelial injury is thought to play a pivotal role in the development and progression of vascular diseases, such as atherosclerosis, hypertension or restenosis, as well as their complications, including myocardial infarction or stroke. Accumulating evidence suggests that bone marrow-derived endothelial progenitor cells (EPCs) promote endothelial repair and contribute to ischemia-induced neovascularization. Coronary artery disease and its risk factors, such as diabetes, hypercholesterolemia, hypertension and smoking, are associated with a reduced number and impaired functional activity of circulating EPCs. Moreover, initial data suggest that reduced EPC levels are associated with endothelial dysfunction and an increased risk of cardiovascular events, compatible with the concept that impaired EPC-mediated vascular repair promotes progression of vascular disease. In this review we summarize recent data on the effects of pharmacological agents on mobilization and functional activity of EPCs. In particular, several experimental and clinical studies have suggested that statins, angiotensin-converting enzyme inhibitors, angiotensin II type 1 receptor blockers, PPAR-gamma agonists and erythropoietin increase the number and functional activity of EPCs. The underlying mechanisms remain largely to be defined; however, they likely include activation of the PI3-kinase/Akt pathway and endothelial nitric oxide synthase, as well as inhibition of NAD(P)H oxidase activity of progenitor cells.
    Expert Review of Cardiovascular Therapy 10/2008; 6(8):1071-82.
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    Circulation. 01/2008; 117:e186.

Publication Stats

673 Citations
215.40 Total Impact Points

Institutions

  • 2008–2012
    • University of Zurich
      • Institute of Physiology
      Zürich, ZH, Switzerland
  • 2007–2011
    • Hannover Medical School
      • Department of Cardiology and Angiology
      Hannover, Lower Saxony, Germany