Determinants of endothelial function in a cohort of patients with peripheral artery disease

RANKL induces beige adipocyte differentiation in preadipocytes

The receptor activator of nuclear factor-κB (NF-κB) (RANK), its ligand (RANKL), and the decoy receptor osteoprotegerin (OPG) are a triad of proteins that regulate bone metabolism, and serum OPG is considered a biomarker for cardiovascular diseases and Type 2 diabetes; however, the implications of OPG in adipose tissue metabolism remains elusive. In this study, we investigate RANK-RANKL-OPG signaling in white adipose tissue browning. Histological analysis of osteoprotegerin knockout (OPG-/-) mice showed subcutaneous white adipose tissue (sWAT) browning, resistance for high-fat diet-induced weight gain, and preserved glucose metabolism compared with wild-type (WT) mice. Stromal vascular fraction (SVF) cells from sWAT of OPG-/- mice showed multilocular morphology and higher expression of brown adipocyte marker genes compared with those from the WT group. Infusion of RANKL induced browning and elevated respiratory rates in sWAT, along with increased whole body oxygen consumption in mice measured by indirect calorimetry. Subcutaneous WAT-derived SVF and 3T3-L1 cells, but not mature white adipocytes, differentiated into beige adipose tissue in the presence of RANKL. Moreover, SVF cells, even under white adipocyte differentiation, showed multilocular lipid droplet, lower lipid content, and increased expression of beige adipocyte markers with RANKL stimulation. In this study, we show for the first time the contribution of RANKL to increase energy expenditure by inducing beige adipocyte differentiation in preadipocytes.

Serum resistin is associated with impaired endothelial function and a higher rate of adverse cardiac events in patients with peripheral artery disease

OBJECTIVE

Resistin is a hormone that has been associated with metabolic syndrome and cardiovascular disease. The role of resistin in patients with peripheral artery disease (PAD) has not been fully explored. This study seeks to understand the relationship between serum resistin, vascular function, and cardiovascular outcomes in patients with PAD.

METHODS

There were 106 patients with PAD who were recruited between 2011 and 2016. Patients attended a baseline visit during which a comprehensive vascular physiology assessment including medical and surgical history, radial artery tonometry, and flow mediated-vasodilation (FMD) was completed. A blood sample was drawn, and serum resistin was assayed using enzyme-linked immunosorbent assay kits. Using the time of study enrollment as the time of origin, incident major adverse cardiac events (MACEs) were identified by subsequent chart review and defined as a composite end point of myocardial infarction, coronary revascularization, transient ischemic attack, stroke, or death from a cardiac cause.

RESULTS

Patients had a mean age of 68 ± 8 years, were largely white (75%), and had comorbidities commonly associated with PAD including hypertension (92%), hyperlipidemia (87%), coronary artery disease (37%), and diabetes mellitus (38%). After stratification by resistin quartile, higher resistin quartiles were significantly associated with an older age, a greater number of pack-years smoked, and a lower estimated glomerular filtration rate. Despite similar comorbidities and medication use, endothelial function, as measured by FMD, was significantly lower with increasing resistin quartile (I, 9.1% ± 3.3%; II, 7.1% ± 3.5%; III, 5.8% ± 4.0%; IV, 5.6% ± 3.5%; P = .002). In multivariable linear regression, higher resistin quartiles (III and IV) were associated with lower FMD relative to quartile I after adjusting for several patient characteristics, medications, and comorbidities (III, -2.26 [95% confidence interval (CI), -4.51 to -0.01; P = .05]; IV, -2.53 [95% CI, -4.87 to -0.20; P = .03]). During a median follow-up period of 36 months (interquartile range, 29-45 months), 21 patients experienced the primary end point. In a Cox proportional hazards model adjusted for smoking status, coronary artery disease, and age, each 1 ng/mL increase in resistin was associated with a 10% increased risk of MACEs (hazard ratio, 1.10; 95% CI, 1.00-1.20; P = .04).

CONCLUSIONS

In patients with PAD, higher levels of resistin were associated with impaired endothelial function and an increased rate of MACEs. These results suggest that resistin may be a marker or effector of impaired vascular physiology and adverse cardiac outcomes in patients with PAD. Further research is needed to determine the potential mechanisms by which resistin may impair endothelial function and increase MACEs in this population.

Role of osteoprotegerin/receptor activator of nuclear factor kappa B/receptor activator of nuclear factor kappa B ligand axis in nonalcoholic fatty liver disease

Concomitantly with the increase in the prevalences of overweight/obesity, nonalcoholic fatty liver disease (NAFLD) has worldwide become the main cause of chronic liver disease in both adults and children. Patients with fatty liver display features of metabolic syndrome (MetS), like insulin resistance (IR), glucose intolerance, hypertension and dyslipidemia. Recently, epidemiological studies have linked obesity, MetS, and NAFLD to decreased bone mineral density and osteoporosis, highlighting an intricate interplay among bone, adipose tissue, and liver. Osteoprotegerin (OPG), an important symbol of the receptor activator of nuclear factor-B ligand/receptor activator of nuclear factor kappa B/OPG system activation, typically considered for its role in bone metabolism, may also play critical roles in the initiation and perpetuation of obesity-related comorbidities. Clinical data have indicated that OPG concentrations are associated with hypertension, left ventricular hypertrophy, vascular calcification, endothelial dysfunction, and severity of liver damage in chronic hepatitis C. Nonetheless, the relationship between circulating OPG and IR as a key feature of MetS as well as between OPG and NAFLD remains uncertain. Thus, the aims of the present review are to provide the existent knowledge on these associations and to discuss briefly the underlying mechanisms linking OPG and NAFLD.

Relation of Biochemical Parameters with Flow-mediated Dilatation in Patients with Metabolic Syndrome

BACKGROUND

Metabolic syndrome (MetS) is one of the high cardiovascular (CV) situations. Endothelial dysfunction, which is a common finding in patients with MetS, is related with increased CV risk. In patients with MetS, the effect of the major CV risk factors, not included in the MetS definition, on endothelial dysfunction is not well known. The aim of this study was to determine the effect of major CV risk factors such as gender, smoking, family history, and biochemical parameters on endothelial dysfunction in patients with MetS.

METHODS

The study was performed between December 2010 and August 2014. A total of 55 patients (15 females and 40 males) with MetS and 81 healthy controls (37 females and 44 males) with a body mass index <25 kg/m2 were enrolled in the study. Endothelial dysfunction was measured by flow-mediated dilatation (FMD), oxidative stress parameters; high-sensitivity C-reactive protein (hs-CRP), oxidized low-density lipoprotein (ox-LDL), endothelial nitric oxide synthase (e-NOS), nitric oxide, and cell adhesion markers; von Willebrand factor, and e-selectin. Platelet aggregation (endothelial adenosine diphosphate), total platelet count, and mean platelet volume were additionally analyzed and demographic parameters were explored. Student's t- test, Mann-Whitney U-test, and Chi-square test were used to analyze the results.

RESULTS

The fasting blood glucose (z= 3.52, P= 0.001), hs-CRP (z = 3.23, P= 0.004), ox-LDL (z = 2.62, P= 0.013), and e-NOS (z = 2.22, P= 0.026) levels and cardiac risk score (z = 5.23, P< 0.001) were significantly higher in patients with MetS compared with the control group. Smoking was correlated with decreased FMD (χ2 = 9.26, P= 0.002) in MetS patients but not in the control group.

CONCLUSIONS

Increased ox-LDL, hs-CRP, and e-NOS are likely to be a result of oxidative stress, a condition in which an imbalance occurs between the production and inactivation of reactive nitrogen and oxygen species. In addition, in patients with MetS, smoking is independently related to endothelial dysfunction.

Biomarkers of Metabolic Syndrome: Biochemical Background and Clinical Significance

Biomarkers of the metabolic syndrome are divided into four subgroups. Although dividing them in groups has some limitations, it can be used to draw some conclusions. In a first part, the dyslipidemias and markers of oxidative stress are discussed, while inflammatory markers and cardiometabolic biomarkers are reviewed in a second part. For most of them, the biochemical background and clinical significance are discussed, although here also a well-cut separation cannot always be made. Altered levels cannot always be claimed as the cause, risk, or consequence of the syndrome. Several factors are interrelated to each other and act in a concerted, antagonistic, synergistic, or modulating way. Most important conclusions are summarized at the end of every reviewed subgroup. Genetic biomarkers or influences of various food components on concentration levels are not included in this review article.

Circulating osteoprotegerin and asymptomatic carotid atherosclerosis in postmenopausal non diabetic women

PURPOSE

Osteoprotegerin (OPG) is a bone metabolism regulator but it is also involved in vascular calcification. Its role in the development of atherosclerosis is still a subject of debate. Postmenopausal women seem to have an increased risk for cardiovascular disease. The aim of the study is to evaluate the relationship between serum OPG and asymptomatic carotid atherosclerosis in postmenopausal non-diabetic women.

MATERIAL/METHODS

Carotid artery examination was performed in 100 postmenopausal women without diabetes mellitus and overt cardiovascular disease, using B-mode ultrasonography to determine the carotid intima-media thickness (CIMT) and the presence of plaques. Serum OPG was measured in all study participants and its relationship with clinical, biochemical and vascular parameters was evaluated.

RESULTS

CIMT correlated with age (r=0.45, p<0.001), years since menopause (r=0.30, p=0.003), abdominal circumference (r=0.25, p=0.01) and OPG (r=0.23, p=0.02). Carotid plaques correlated with age (p<0.001), obesity (p=0.03), abdominal circumference (p=0.03) and CIMT (p<0.001), but not with serum OPG (p=0.86). In regression analyses the independent predictors for CIMT were age (β=0.717, p<0.001), OPG (β=0.214, p=0.02), and years since menopause (β=-0.334, p=0.04) and for the presence of carotid plaques were obesity (p=0.04, OR=3.90), CIMT (p<0.001, OR=6408.86) and smoking (p=0.02, OR=687.93).

CONCLUSION

OPG is associated with cardiovascular risk factors, CIMT, but not with the presence of asymptomatic carotid plaques in non diabetic postmenopausal women. OPG may be a marker of cardiovascular risk.

Osteoprotegerin is not a determinant of metabolic syndrome in sub-Saharan Africans after age adjustment

OBJECTIVES

Osteoprotegerin (OPG), a soluble member of tumor necrosis factor receptor superfamily that inhibits bone resorption, has been suggested as a cardiovascular risk factor in humans. In this study, we aim to investigate the potential relationship between OPG and MetS (MetS) in a sub-Saharan African population.

METHODS

Four hundred and eleven volunteers (152 men, 259 women) aged ≥18 years recruited from the general population in Douala and Edea, Cameroon participated in this study. Anthropometric parameters measured and blood samples were collected for glucose, serum lipids and OPG concentrations measurements. Mean differences of the variables in different groups were compared using Students' t test. We performed logistic regressions to analyze the impact of independent factors on the relation between OPG and MetS outcome. MetS was defined using the Joint Interim Statement 2009.

RESULTS

OPG levels did not vary significantly between both men and women with and without MetS (both P>0.05). However, with high fasting blood glucose (≥5.6 mmol/L) had a significantly higher OPG level than those with lower glucose level (P=0.014). In multiple logistic regression analysis, MetS did not show any significant association with serum OPG levels in men and women after adjusting for age, physical activity, alcohol consumption and menopausal status in women (P=0.720 and P=0.930 respectively).

CONCLUSION

This study failed to demonstrate any relationship between OPG and MetS. Nevertheless, the positive association between blood glucose and OPG levels reveals that OPG might be involved in cardiovascular risk development in this sub-Saharan African population.

Leptin is associated with vascular endothelial function in overweight patients with type 2 diabetes

BACKGROUND

The adipocyte-derived hormone leptin plays a key role in the regulation of appetite and body weight. Recent studies have suggested that leptin is also involved in the pathogenesis of obesity-related atherosclerosis and cardiovascular disease. In this study, we investigated the association of plasma leptin levels with vascular endothelial function in lean and overweight patients with type 2 diabetes.

METHODS

One hundred seventy-one type 2 diabetic patients, of which 85 were overweight (body mass index (BMI) ≥ 25 kg/m2), were enrolled in this cross-sectional study. Plasma leptin concentrations were measured by enzyme-linked immunosorbent assay. Flow-mediated dilatation (FMD) of the brachial artery was measured to evaluate vascular endothelial function using ultrasound.

RESULTS

No significant difference in FMD was found between the lean and overweight groups (7.0 ± 3.8% and 6.5 ± 3.6%, respectively; p = 0.354). FMD was negatively correlated with age (r = -0.371, p < 0.001) and serum creatinine levels (r = -0.236, p = 0.030), but positively correlated with BMI (r = 0.330, p = 0.002) and plasma leptin levels (r = 0.290, p = 0.007) in the overweight group. FMD was not associated with any parameters in the lean group. Multiple regression analysis including possible atherosclerotic risk factors revealed that the plasma leptin level (β = 0.427, p = 0.013) was independently associated with FMD in the overweight group (R2 = 0.310, p = 0.025), but not the lean group.

CONCLUSION

Plasma leptin levels are associated with vascular endothelial function in overweight patients with type 2 diabetes.

n-3 Polyunsaturated fatty acids supplementation in peripheral artery disease: the OMEGA-PAD trial

Despite current consensus guidelines recommending intensive cardiovascular risk factor management for peripheral artery disease (PAD), patients suffering from PAD continue to experience significant morbidity and mortality. This excess morbid burden is at least partially related to impaired vascular function and systemic inflammation. Interventions bridging this gap are critical. Dietary supplementation of n-3 polyunsaturated fatty acids (n-3 PUFA) has been shown to improve endothelial function and reduce inflammation in different cohorts, as well as to decrease cardiovascular events in secondary prevention trials in patients with coronary artery disease. Their effects in the PAD population are, however, less well understood. The OMEGA-PAD trial is a double-blinded, randomized, placebo-controlled trial that examines the impact of a high-dose, short-duration dietary oral supplementation of n-3 PUFA on vascular function and inflammation in patients with established PAD. The purpose of this article is to provide a detailed description of the design and methods of the OMEGA-PAD trial, and a summary of baseline characteristics of the cohort.

Does brachial artery flow-mediated vasodilation provide a bioassay for NO?

This study sought to better define the role of NO in brachial artery flow-mediated vasodilation (FMD) in young, healthy humans. Brachial artery blood velocity and diameter were determined (ultrasound Doppler) in 8 volunteers (26 ± 1 year) before and after 5-minute forearm circulatory occlusion with and without intra-arterial infusion of the endothelial NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA; 0.48 mg/dL per minute). Control (CON) and L-NMMA trials were performed with the occlusion cuff placed in the traditional distal position, as well as proximal to the measurement site. FMD was significantly reduced, but not abolished, by L-NMMA in the distal cuff trial (8.9 ± 1.3%-6.0 ± 0.7%, CON versus L-NMMA; P=0.02), with no effect of L-NMMA on FMD with proximal cuff placement (10.6 ± 1.2%-12.4 ± 1.7%, CON versus L-NMMA; P=0.39). When the reduction in shear stimulus after L-NMMA was taken into account, no drug difference was observed for either distal (0.26 ± 0.02-0.23 ± 0.03, CON versus L-NMMA; P=0.40) or proximal (0.23 ± 0.08-0.23 ± 0.03, CON versus L-NMMA; P=0.89) FMD trials. These findings challenge the assertion that NO is obligatory for brachial artery FMD and call into question the sensitivity of this procedure for noninvasive determination of NO bioavailability in young, healthy humans.

The role of osteoprotegerin in cardiovascular disease

Osteoprotegerin (OPG) is a 401 amino acid N-glycosylated protein, which is highly expressed in a large number of tissues. OPG mainly binds to two ligands, i.e. RANKL (receptor activator of nuclear factor κB ligand) and TRAIL (tumor necrosis factor- related apoptosis-inducing ligand). Upon binding to the former ligand, OPG inhibits the activation of osteoclasts and promotes apoptosis of osteoclasts, whereas the binding of OPG with TRAIL prevents apoptosis of tumor cells. There is now emerging evidence that OPG participates in the pathogenesis of atherosclerosis and cardiovascular diseases by amplifying the adverse effects of inflammation and several traditional risk factors such as hyperlipidemia, endothelial dysfunction, diabetes mellitus, and hypertension. Some epidemiological studies also showed a positive association between OPG levels and cardiovascular morbidity and mortality. The aim of this article is to provide an overview of the main biochemical, physiological, and pathological aspects of OPG biology in cardiovascular disease.

Correlation of plasma osteoprotegerin (OPG) and receptor activator of the nuclear factor κB ligand (RANKL) levels with clinical risk factors in patients with advanced carotid atherosclerosis

Background

Osteoprotegerin (OPG) is considered to be a crucial regulatory mediator of bone metabolism by acting as a decoy receptor of the receptor activator of nuclear factor κB ligand (RANKL). OPG and RANKL have further become the subject of intense interest for their potential role in cardiovascular disease. The present study aimed to assess the clinical implication of plasma OPG and RANKL levels in patients with advanced carotid atherosclerosis

Material/Methods

Plasma OPG and RANKL concentrations measured by solid-phase enzyme-linked immunosorbent assay (ELISA) were correlated with medical history, risk factors and medication intake in 131 patients who underwent carotid endarterectomy for vascular repair.

Results

Plasma OPG concentrations were associated with patients’ age (p=0.0258), homocysteine levels (p<0.00001), eGFR (p=0.0254), history of diabetes (p=0.0324), statins therapy (p=0.0044), hyperlipidemia (p=0.0407), smoking (p=0.0226) and CAD (p=0.0377). Plasma RANKL concentrations were associated with patients’ age (p=0.0191), homocysteine levels (p<0.00001), history of smoking (p=0.0185) and statins therapy (p=0.0004). Diabetes, CAD, smoking status, statins therapy and homocysteine were identified as independent predictors of OPG concentrations (p=0.0157, p=0.0030, p=0.0249, p=0.0047 and p=0.0072, respectively), whereas smoking showed an independent effect for RANKL (p=0.0010).

Conclusions

The present data reinforce the clinical utility of OPG in carotid atherosclerosis, whereas the clinical implication of RANKL seems uncertain.

Risk factors for metabolic syndrome independently predict arterial stiffness and endothelial dysfunction in patients with chronic kidney disease and minimal comorbidity

OBJECTIVE

Metabolic syndrome (MS) is common in patients with chronic kidney disease (CKD), but its contribution to arterial stiffness and endothelial dysfunction in CKD is not well defined. We hypothesized that risk factors for MS would independently predict arterial stiffness and endothelial dysfunction in CKD patients.

RESEARCH DESIGN AND METHODS

Risk factors for MS, carotid-femoral pulse wave velocity (CF-PWV) and flow-mediated dilation (FMD) as measures of arterial stiffness and endothelial dysfunction, respectively, were assessed in 113 minimally comorbid CKD patients and in 23 matched control subjects.

RESULTS

CF-PWV correlated with systolic blood pressure (SBP), waist circumference, and plasma glucose (r(2) = 0.25, 0.09, and 0.09; P < 0.01 for all). FMD correlated with SBP (r(2) = 0.09; P < 0.01) and waist circumference (r(2) = 0.03; P < 0.05). CF-PWV increased progressively (r(2) = 0.07; P < 0.01) with increasing number of risk factors for MS. In multiple linear regression, SBP and waist circumference were independent determinants of CF-PWV, whereas only SBP predicted FMD.

CONCLUSIONS

The number of MS risk factors is an important determinant of arterial stiffness in CKD patients irrespective of the degree of renal impairment. Although BP remains the major determinant of arterial stiffness and endothelial dysfunction, waist circumference independently predicts arterial stiffness. MS risk factors, particularly abdominal girth, are potential targets for future interventional studies in patients with CKD.

Comparison of osteoprotegerin to traditional atherosclerotic risk factors and high-sensitivity C-reactive protein for diagnosis of atherosclerosis

Atherosclerosis is the main cause of cardiovascular disease, but the extent of atherosclerosis in individual patients is difficult to estimate. A biomarker of the atherosclerotic burden would be very valuable. The aim of the present study was to evaluate the association of plasma osteoprotegerin (OPG) to clinical and subclinical atherosclerotic disease in a large community-based, cross-sectional population study. In the Copenhagen City Heart Study, OPG concentrations were measured in 5,863 men and women. A total of 494 participants had been hospitalized for ischemic heart disease or ischemic stroke, and compared to controls, this group with clinical atherosclerosis had higher mean OPG (1,773 vs 1,337 ng/L, p <0.001) and high-sensitivity C-reactive protein (2.3 vs 1.6 mg/L, p <0.001). In a multivariate model with age, gender, body mass index, hypertension, diabetes, hypercholesterolemia, smoking status, estimated glomerular filtration rate, high-sensitivity C-reactive protein, and OPG, OPG remained significantly associated with clinical atherosclerosis (p <0.01); high-sensitivity C-reactive protein, in contrast, did not (p = 0.74). In the control group without clinical atherosclerosis, OPG was independently associated with hypertension, diabetes, hypercholesterolemia, smoking, and subclinical peripheral atherosclerosis as measured by ankle brachial index. For each doubling of the plasma OPG concentration, the risk for subclinical peripheral atherosclerosis increased by 50% (p <0.001) after multivariate adjustment. In conclusion, OPG appears to be a promising biomarker of atherosclerosis that is independently associated with traditional risk factors of atherosclerosis, subclinical peripheral atherosclerosis, and clinical atherosclerotic disease such as ischemic heart disease and ischemic stroke.

Assessment of the genetic effects of polymorphisms in the osteoprotegerin gene, TNFRSF11B, on serum osteoprotegerin levels and carotid plaque vulnerability

BACKGROUND AND PURPOSE

Osteoprotegerin (OPG) is a secretory glycoprotein which belongs to the tumor necrosis factor receptor family. Various mechanisms have been suggested by which calcification might alter atherosclerotic plaque stability, but the significance of this intimal calcification is controversial. High concentrations of OPG have been associated with the presence of vascular and cardiovascular diseases. This study was designed to assess the association between gene polymorphisms of the OPG gene (TNFRSF11B), the serum OPG level, and plaque stability in patients with carotid atherosclerosis.

METHODS

We studied 177 patients with internal carotid artery stenosis who underwent carotid endarterectomy and also 303 controls. Carotid endarterectomy samples removed from patients were assessed by immunohistochemistry. Concentrations of OPG were measured and gene polymorphisms were examined by polymerase chain reaction and restriction enzyme analysis and were compared, initially between patients with carotid atherosclerosis and controls, and subsequently between stable and unstable carotid plaques.

RESULTS

We found that the GG genotype of the T245G polymorphism, the CC genotype of the T950C polymorphism, and the CC genotype of the G1181C polymorphism were significantly higher in patients with carotid plaque than in controls (21.5% versus 10.9% , P<0.01; 15.8% versus 7.6%, P<0.01; and 20.3% versus 10.9%, P<0.01, respectively) and that these polymorphisms were associated with high serum OPG levels (4.02 [3.07] versus 2.94 [1.81] pmol/L; P<0.01), which were significantly higher in patients with unstable atherosclerotic plaques (5.86 [4.02] versus 3.53 [1.87] pmol/L; P<0.01).

CONCLUSIONS

The TNFRSF11B gene polymorphisms studied are associated with high serum OPG levels and might be potential markers for plaque instability.

The role of osteoprotegerin (OPG) receptor activator for nuclear factor kappaB ligand (RANKL) in cardiovascular pathology - a review

Initially described as key regulators in metabolic bone disease osteoprotegerin (OPG), receptor activator of nuclear factor kappa B (RANK) and RANK ligand (RANKL) have also been discriminated as regulators in immunologic function. Cardiovascular diseases (CVD) develop over many years in life and are often triggered by inflammatory processes within the vessel wall that lead to vascular remodeling. Recently some study groups have described OPG as a prognostic parameter for mortality and morbidity in cardiovascular patients.

Association of increased parathyroid hormone with neuroendocrine activation and endothelial dysfunction in elderly men with heart failure

High PTH levels have been reported in patients with chronic heart failure (CHF). Similarly, its levels increase with aging and are related to impaired survival in elderly adults. However, its relationship with neuroendocrine activation and endothelial dysfunction in CHF has not been previously studied. Seventy-three CHF males with New York Heart Association (NYHA) classes II and III and 20 control subjects aged ≥ 55 yr were recruited. PTH, 25-hydroxyvitamin D [25(OH)D], N-terminal pro-brain natriuretic peptide (NT-pro-BNP), adiponectin, and osteoprotegerin were measured. Endothelial function (brachial flow mediated dilation), echocardiography, physical performance, and quality of life were assessed, as well. CHF patients had markedly increased serum PTH (77 ± 33 vs 40 ± 11 pg/ml, p<0.0001), NT-pro-BNP [1809 (2742) vs 67 (74) pg/ml, p<0.0001], adiponectin (17 ± 9 vs 10 ± 2 μg/ml, p<0.0001), osteoprotegerin, whereas 25(OH)D levels were decreased compared to controls. Increased PTH is positively correlated with NTpro- BNP (r=0.399, p<0.0001), adiponectin (r=0.398, p<0.0001), and osteoprotegerin, whereas negatively with 25(OH)D in CHF patients. Additionally, increased serum PTH was associated with endothelial dysfunction, echocardiographic variables of heart failure progression, impaired physical performance, and deteriorated quality of life. In a multivariate linear regression analysis, increased serum PTH was independently associated with neuroendocrine activation (NT-pro-BNP, adiponectin) and endothelial dysfunction in elderly CHF men (R2=0.455). Additionally, demonstrated relations with other well-established variables of heart failure severity suggest the potential role of serum PTH in the pathogenesis and non-invasive monitoring of heart failure progression. Future studies are needed to evaluate the predictive value of serum PTH for clinical outcomes as well as beneficial potential of PTH suppression in CHF patients.

Increased osteoprotegerin levels in women with previous gestational diabetes developing metabolic syndrome

Osteoprotegerin (OPG), a novel soluble member of tumour necrosis factor receptor superfamily, has been shown to link cardiovascular disorders. The aim of this study is to investigate the potential relationship between serum OPG levels, cardiovascular risk factors and metabolic syndrome in a relatively large group of women with previous GDM. In this cross-sectional case-control study, 128 women with previous GDM and 67 age-matched controls were enrolled. Subjects were evaluated for the diagnosis of metabolic syndrome according to the criteria of the American Heart Association (AHA). Fasting glucose, insulin, serum lipids, CRP and OPG were assayed. HOMA score was calculated. Carotid intima media thickness (IMT) was measured. There was no significant increase in OPG levels in women with previous GDM when compared to controls. On the other hand, women with previous GDM developing metabolic syndrome had higher OPG levels than those without metabolic syndrome and healthy controls. Serum OPG levels were associated with obesity, insulin resistance, serum CRP and carotid IMT. Serum OPG is related to cardiovascular risk factors and metabolic syndrome, and might be involved in the development of cardiovascular disorders in women with previous GDM.

Adiponectin is related with carotid artery intima-media thickness and brachial flow-mediated dilatation in young adults--the Cardiovascular Risk in Young Finns Study

AIMS

Adiponectin may be involved in the pathogenesis of atherosclerosis. We investigated the relation of adiponectin on early functional and structural markers of subclinical atherosclerosis in a large population-based cohort of young men and women.

METHODS AND RESULTS

We measured serum adiponectin using radioimmunoassay in 2,147 young adults (ages 24-39 years) participating in the Cardiovascular Risk in Young Finns Study. The subjects had ultrasound data on carotid intima-media thickness (IMT), carotid artery elasticity (n = 2,139) and brachial flow-mediated dilatation (FMD) (n = 1,996). In univariate analysis, adiponectin was inversely associated with IMT (r = -0.16, P < 0.0001) and directly with FMD (r = 0.12, P < 0.0001) and carotid elasticity (r = 0.20, P < 0.0001). The associations for IMT and FMD remained significant in multivariable models adjusted for age, sex, obesity indices, serum lipids, blood pressure, leptin, glucose, and C-reactive protein: IMT (β = -0.018 ± 0.005, P = 0.0002) and FMD (β = 0.72 ± 0.25, P = 0.004). The relation between adiponectin and carotid elasticity attenuated to non-significant after adjusting for waist circumference and systolic blood pressure.

CONCLUSION

In young healthy adults, low serum adiponectin concentration is independently related with increased carotid IMT and attenuated brachial FMD, supporting the role of adiponectin in the pathogenesis of early atherosclerosis.

Endothelial dysfunction evaluated by flow mediated dilation is strongly associated to metabolic syndrome in the elderly

This study was carried out to assess whether endothelial dysfunction, evaluated by flow-mediated dilation (FMD), is related to the occurrence of the Metabolic Syndrome (MetS) in old age. Eighty patients (25 men and 55 women), mean age 74.1±7.4 years (range 65-99 yrs) were studied. Information on all subjects, medical history and regular medications was obtained. Subjects underwent a clinical examination and laboratory tests. The presence of MetS was evaluated according to the revised NCEP-ATP III criteria. An ultrasound vascular examination (US) of the carotid and brachial arteries was performed in all patients. Intima-media thickness (IMT), presence of plaques (PL), endothelium-dependent (EDV) and -independent vasodilation (EIDV) were also evaluated. Patients were divided into two groups according to the presence/absence of MetS. Significant differences were found between MetS and non MetS patients in: EDV (p<0.01), EIDV (p<0.05) and Homeostatic model assessment index (HOMA) (p<0.02), but not in IMT or PL. MetS was significantly associated with FMD reduction (R 0.4, p<0.005) independently of all possible confounding factors other than EIDV, IMT and PL.

Association of osteoprotegerin with aortic stiffness in patients with symptomatic peripheral artery disease and in healthy subjects

BACKGROUND

Arterial stiffening is an independent predictor for cardiovascular mortality. Preliminary studies have shown that arterial calcification may have an impact on increased vascular stiffness. However, there are limited data about the role of calcification inhibitor osteoprotegerin (OPG) as an independent predictor for arterial stiffness in patients with peripheral arterial disease (PAD) and in healthy subjects. The aim of this study was to evaluate the association between OPG and arterial stiffness parameters in patients with PAD and in healthy subjects.

METHODS

We studied 69 men with PAD (age 63 + or - 7 years) and 68 healthy subjects (age 54 + or - 8 years). Serum OPG and oxidized low-density lipoprotein (oxLDL) were measured using the enzyme-linked immunosorbent assay method. Radial and aortic pulse wave velocity (aPWV) and augmentation index (AIx) were determined by applanation tonometry.

RESULTS

The OPG (5.4 + or - 1.7 vs. 4.4 + or - 1.1 pmol/l; P < 0.001) and aPWV (10.1 + or - 2.5 vs. 7.6 + or - 1.6 m/s; P < 0.001) were different for the patients and for the controls. There was a linear relationship between OPG and aPWV in patients with PAD (R = 0.37; P = 0.003) and in healthy individuals (R = 0.40; P = 0.001). In multiple regression models after adjustment for potential confounders, OPG was independently associated with aPWV in the patients (R(2) = 0.47; P < 0.0001) and in the controls (R(2) = 0.44; P < 0.0001). The AIx or radial PWV was not correlated with OPG for either group.

CONCLUSION

The independent association between OPG and aPWV in patients with PAD and in controls suggests that the calcification inhibitor OPG may influence aortic stiffening in atherosclerosis and in clinically healthy subjects.

Osteoprotegerin in relation to type 2 diabetes mellitus and the metabolic syndrome in postmenopausal women

Osteoprotegerin (OPG) is an inhibitor of bone resorption. Circulating levels of OPG seem to be elevated in patients with cardiovascular disorders and diabetes. The relationship between OPG and the metabolic syndrome has never been studied in postmenopausal women. In a population-based study, 382 Iranian postmenopausal women were randomly selected. Cardiovascular risk factors, high-sensitivity C-reactive protein, and OPG were measured. The diabetes classification and the metabolic syndrome definition were based on the criteria of the American Diabetes Association and the National Cholesterol Education Program-Adult Treatment Panel III, respectively. The mean serum OPG level was higher in those with type 2 diabetes mellitus than those without diabetes (4.33 +/- 1.70 vs 3.84 +/- 1.76 pmol/L, P = .016). In multiple logistic regression analysis, type 2 diabetes mellitus showed a significant association with serum OPG levels when adjustments were made for age, high-sensitivity C-reactive protein, and cardiovascular risk factors (odds ratio = 2.21; confidence interval, 1.34-3.66; P = .002). No significant difference was found between the mean serum OPG levels of those with the metabolic syndrome and those without the metabolic syndrome. Mean OPG levels did not differ significantly between subjects with and without hypertension, dyslipidemia, glucose intolerance, or abdominal obesity according to the National Cholesterol Education Program-Adult Treatment Panel III criteria. In conclusion, circulating OPG levels are significantly associated with diabetes, independent of cardiovascular risk factors in postmenopausal women. However, OPG levels have no correlation with the metabolic syndrome or its components. Further studies are warranted to determine the pathophysiologic origin of elevated OPG in type 2 diabetes mellitus.

Does the DASH diet lower blood pressure by altering peripheral vascular function?

We tested whether lowering of blood pressure (BP) on the dietary approaches to stop hypertension (DASH) diet was associated with changes in peripheral vascular function: endothelial function, assessed by flow-mediated vasodilatation (FMD) of the brachial artery, and subcutaneous adipose tissue blood flow (ATBF). We also assessed effects on heart rate variability (HRV) as a measure of autonomic control of the heart. We allocated 27 men and women to DASH diet and control groups. We measured FMD, ATBF and HRV on fasting and after ingestion of 75 g glucose, before and after 30 days on dietary intervention, aiming for weight maintenance. The control group did not change their diet. The DASH-diet group complied with the diet as shown by significant reductions in systolic (P<0.001) and diastolic (P=0.005) BP, and in plasma C-reactive protein (P<0.01), LDL-cholesterol (P<0.01) and apolipoprotein B (P=0.001), a novel finding. Body weight changed by <1 kg. There were no changes in the control group. We found no changes in FMD, or in ATBF, in the DASH-diet group, although heart rate fell (P<0.05). Glucose and insulin concentrations did not change. In this small-scale study, the DASH diet lowered BP independently of peripheral mechanisms.

Osteoprotegerin, vascular calcification and atherosclerosis

The association of bone pathologies with atherosclerosis has stimulated the search for common mediators linking the skeletal and the vascular system. Since its initial discovery as a key regulator in bone metabolism, osteoprotegerin (OPG) has become the subject of intense interest for its role in vascular disease and calcification. Studies in vitro and in animal models suggest that OPG inhibits vascular calcification. Paradoxically however, clinical studies suggest that serum OPG levels increase in association with vascular calcification, coronary artery disease, stroke and future cardiovascular events. This has led to an extensive debate on the potential of OPG as a biomarker of vascular disease. However the exact significance and mechanisms by which this bone-regulatory protein influences cardiovascular pathophysiology is still unclear. The need for a more complete picture is being addressed in increasing valuable research indicating OPG as not only a marker but also a mediator of vascular pathology modulating osteogenic, inflammatory and apoptotic responses. By integrating the results of recent experimental research, animal models and clinical studies, this review summarises the present understanding of the role of OPG in vascular disease and calcification.