Low plasma adiponectin is associated with coronary artery disease but not with hypertension in high-risk nondiabetic patients

Adipokines and Autoimmunity in Inflammatory Arthritis

Adipokines are adipose tissue-derived factors not only playing an important role in metabolism but also influencing other central processes of the body, such as inflammation. In autoimmune diseases, adipokines are involved in inflammatory pathways affecting different cell types. Many rheumatic diseases belong to the group of autoimmune diseases, for example rheumatoid arthritis (RA) and psoriatic arthritis. Due to the autoimmune responses, a chronic inflammatory milieu develops, which affects the whole body, including adipose tissue. Metabolic alterations such as obesity influence inflammatory responses in autoimmune diseases. Adipokines are bioactive mediators mainly produced by adipose tissue. Due to alterations of systemic adipokine levels, their role as biomarkers with diagnostic potential has been suggested in the context of rheumatic diseases. In the affected joints of RA patients, different synoviocytes but also osteoclasts, osteoblasts, and chondrocytes produce several adipokines, contributing to the unique inflammatory microenvironment. Adipokines have been shown to be potent modulatory effectors on different cell types of the immune system but also local cells in synovial tissue, cartilage, and bone. This review highlights the most recent findings on the role of adipokines in the pathophysiology of inflammatory arthritis with a distinct focus on RA in the quickly developing research field.

Serum adipocytokines and adiposity as predictive indices of preeclampsia

BACKGROUND

This study was aimed at determining the levels of serum adiponectin, leptin, resistin, visfatin and lipids during the first trimester in pregnant women and to evaluate the relationship between these biochemical markers and preeclampsia (PE). Available evidence point to changes in the levels of these adipokines in PE hence this study examined the potential of using these biomarkers in the prediction of the disease.

METHODS

This was a case-control study which compared first trimester serum biochemical and anthropometric parameters in pregnant women who subsequently developed PE and those who did not. Blood pressure and urine protein were determined after 20 weeks of gestation and diagnosis of PE performed according to the guidelines of the American Heart Association.

RESULTS

There was no significant difference (p > 0.05) in the lipid profile with the exception of HDL cholesterol which was significantly lower (p = 0.043) in the PE group compared to the normotensive group. There were, however, significant differences (p <  0.05) in the adipokines between the PE group and those without PE. Analyses of area under the receiver operating characteristic curves (AUCs) for the adipokines, showed their ability to correctly predict PE even after controlling for body mass index (BMI) and family history of hypertension.

CONCLUSION

Adiponectin, leptin, resistin and visfatin were found to be significant predictors of PE, with resistin being the best predictor after controlling for BMI. However, adiponectin was the best predictor after controlling for BMI, age, parity and family history of diabetes and preeclmapsia.

Epicardial adipose tissue as a metabolic transducer: role in heart failure and coronary artery disease

Obesity and diabetes are strongly associated with metabolic and cardiovascular disorders including dyslipidemia, coronary artery disease, hypertension, and heart failure. Adipose tissue is identified as a complex endocrine organ, which by exerting a wide array of regulatory functions at the cellular, tissue and systemic levels can have profound effects on the cardiovascular system. Different terms including "epicardial," "pericardial," and "paracardial" have been used to describe adipose tissue deposits surrounding the heart. Epicardial adipose tissue (EAT) is a unique and multifaceted fat depot with local and systemic effects. The functional and anatomic proximity of EAT to the myocardium enables endocrine, paracrine, and vasocrine effects on the heart. EAT displays a large secretosome, which regulates physiological and pathophysiological processes in the heart. Perivascular adipose tissue (PVAT) secretes adipose-derived relaxing factor, which is a "cocktail" of cytokines, adipokines, microRNAs, and cellular mediators, with a potent effect on paracrine regulation of vascular tone, vascular smooth muscle cell proliferation, migration, atherosclerosis-susceptibility, and restenosis. Although there are various physiological functions of the EAT and PVAT, a phenotypic transformation can lead to a major pathogenic role in various cardiovascular diseases. The equilibrium between the physiological and pathophysiological properties of EAT is very delicate and susceptible to the influences of intrinsic and extrinsic factors. Various adipokines secreted from EAT and PVAT have a profound effect on the myocardium and coronary arteries; targeting these adipokines could be an important therapeutic approach to counteract cardiovascular disease.

Relationship of Plasma Adiponectin and Waist-hip Ratio with Coronary Artery Disease

BACKGROUND

This study aimed to investigate correlation between adiponectin and waist-hip-ratio with severity of coronary artery disease (CAD). There is uncertainty about the association between circulating concentrations of adiponectin and CAD.

METHODS

We enrolled eighty-two consecutive patients undergoing non-urgent coronary angiography for CAD survey. According to the angiography results, the patients were divided into two groups in 1:1 ratio patients admitted with a diagnosis of CAD and non-CAD. We conducted hospital based research, involving study group with documented angiographically CAD, and control group without evidence of CAD. Angiograms were also quantified for the extent and severity of CAD by the Gensini scoring system. We measured baseline adiponectin levels in stored serum samples of all patients, anthropometric and biochemical risk factors were assessed in both groups.

RESULTS

The presence of CAD was associated with current smoking, male gender, waist-hip ratio (WHR) and left ventricular ejection fraction (LVEF). Baseline adiponectin concentrations correlated significantly in terms of the lipid parameters, positively with HDL cholesterol concentrations (r=0.327, P=0.028, P<0.05) and serum triglyceride concentrations were correlated negatively (r=-0.513, P<0.001). No significant difference between median adiponectin levels at baseline was observed between cases and controls.

CONCLUSION

There is a significant positive correlation between waist-hip ratio and presence and severity of coronary artery disease. In conclusion, there is a significant positive correlation between adiponectin and Gensini score among Kosovar patients.

Circulating levels of adiponectin and extent of coronary artery disease in patients undergoing elective coronary angiography

Adiponectin (APN), an adipose tissue-released adipokine with demonstrated anti-inflammatory and anti-atherogenic properties, is encoded by a gene whose polymorphisms are associated with presence of coronary artery disease (CAD). Serum APN levels are inversely related with presence and complexity of CAD. Within this context, we sought to compare levels of total APN and its high molecular weight form (HMW APN) according to clinical presentation and extent of CAD in patients undergoing elective cardiac catheterization. From March 2008 to June 2010, clinical data and blood samples for APN and HMW APN measurements were collected from 415 subjects undergoing cardiac catheterization at two tertiary centers. CAD extent was estimated by the number of coronary arteries with significant stenosis (≥70% obstruction in a major coronary artery) and by Duke Jeopardy Score (DJS). Serum APN levels were similar between groups with stable or unstable CAD (APN 9.20±5.88 vs 9.47±6.23 μg/mL, P=0.738, and HMW APN 5.31±3.72 vs 5.91±4.16 μg/mL, P=0.255), even after stratification by the number of arteries involved (single-vessel vs multivessel disease: APN 9.39±5.76 vs 9.26±6.27 μg/mL, P=0.871; HMW APN 5.29±3.79 vs 5.83±4.04 μg/mL, P=0.306) and DJS score (APN, P=0.718; HMW APN, P=0.276). We conclude that APN and HMW APN serum levels are similar across clinical presentations and different extents of CAD, despite being significantly lower in the presence of obstructive CAD.

Lipoprotein-associated phospholipase A2 single-nucleotide polymorphisms and cardiovascular events in patients with coronary artery disease

AIMS

We tested the hypothesis that variations in the PLA2G7 gene encoding the lipoprotein-associated phospholipase A2 (Lp-PLA2), an enzyme deemed to have proatherogenic activity, affect the Lp-PLA2 levels and predicts cardiovascular events.

METHODS

Using a prospective cohort study design, we investigated incident cardiovascular events as a function of the PLA2G7 gene for rs1805017, rs1805018, and rs1051931 single-nucleotide polymorphisms (SNPs) in 643 randomly selected white patients from the GENICA Study, who at baseline underwent coronary angiography, measurement of Lp-PLA2 mass and activity. Cardiovascular event-free survival was compared across the genotypes by Cox regression, propensity score matching, and haplotype analysis.

RESULTS

The rs1805018 SNP did not follow the Hardy-Weinberg equilibrium and was not further explored. The rs1805017 GG genotype had a lower Lp-PLA2 mass and a higher Lp-PLA2 activity, thus suggesting that this SNP is functional. Long-term follow-up (median 7.8 years) was obtained in 75% of the cohort and allowed recording of incident cardiovascular events in 25.8% of the patients. On Cox regression analysis, the common rs1805017 GG genotype predicted acute myocardial infarction (AMI) [hazard ratio 1.75, 95% confidence interval (CI) 1.03-2.99, P = 0.041]; this finding was confirmed on propensity score matching (82.6% AMI-free survival in GG vs. 94.4% in GA + AA, P = 0.003). The rs1805017 and rs1051931 G/G haplotype was also associated with AMI (52.7 vs. 42.2%, P = 0.026) and cardiovascular event incidence (49.5 vs. 41.7%, P = 0.025).

CONCLUSION

In high-risk coronary artery disease patients of European ancestry, the PLA2G7 rs1805017 GG genotype is associated with increased Lp-PLA2 plasma activity and AMI.

Lipid, adipokine and ghrelin levels in myocardial infarction patients with insulin resistance

Background

Insulin resistance (IR) is a risk factor for ischaemic heart disease and myocardial infarction (MI). IR often manifests in MI and is regarded as an independent predictor of in-hospital mortality, which can provide early risk stratification for recurrent acute coronary events.

Methods

The study enrolled 200 patients (130 males and 70 females aged 61.4 ± 1.12 years) diagnosed with ST elevation MI. At days 1 and 12 from the MI onset, IR levels and lipid profiles, as well as serum glucose, insulin, adipokine and ghrelin levels, were measured.

Results

Free fatty acid (FFA) levels had the most pronounced changes: IR patients had a 9-fold increase in FFA levels at day 1, and patients without IR had a 6-fold increase. Leptin levels at days 1 and 12, in IR patients were, on average, 1.5- and 2-fold higher compared to the controls and patients with no IR (р < 0.05). Leptin levels in IR patients were increased throughout the entire hospital stay. Resistin levels in IR patients were, on average, 1.4-fold higher throughout the entire hospital stay, while in non-IR patients, resistin levels were similar to the controls. Adiponectin levels in IR patients were decreased compared to the controls, while in patients with IR, they were similar to the controls. Both IR and non-IR MI patients had 3-fold and 3.7-fold lower ghrelin levels at day 1, respectively, compared to the controls. The correlation analysis showed a negative correlation between ghrelin and FFA (r = −0.48 р = 0.007), ghrelin and leptin (r = −0.4 р = 0.003), ghrelin and insulin (r = −0.54 р = 0.002), and ghrelin and glucose (r = −0.31 р = 0.002) in MI patients.

Conclusion

Dyslipidaemia, along with insulinaemia and glycaemia, is one of the most significant IR risk factors in the acute and early recovery phases of MI. Dyslipidaemia is characterised by a high FFA level; an imbalance of leptin, resistin, and adiponectin; and a deficiency of ghrelin in the acute and early recovery periods of MI. FFA and ghrelin can be used as promising molecular markers to stratify the risk of recurrent acute coronary events and diabetes mellitus in MI patients.

Adipokines and melanocortins in the hepatic manifestation of metabolic syndrome: nonalcoholic fatty liver disease

Metabolic syndrome is associated with nonalcoholic fatty liver disease and its more aggressive form, nonalcoholic steatohepatitis. Adipokines produced by white adipose tissue possess broad physiological activity and play an important autocrine role in obesity-associated complications, including metabolic syndrome, nonalcoholic fatty liver disease and cardiovascular disease. Various adipokines may have beneficial or harmful effects. Other tissues, particularly stomach and intestine, produce active molecules that can influence the function of adipocytes and, possibly, the levels of adipokine secretion. In some cases, the production sites of these molecules remain unknown. The review focuses on our current understanding of the disease-related effects of the adipokines and the melanocortins on various peripheral tissues, and discusses some of their potential interactions with each other. Potential therapeutic applications are also considered.

Role of adipokines in cardiovascular disease

The discovery of leptin in 1994 sparked dramatic new interest in the study of white adipose tissue. It is now recognised to be a metabolically active endocrine organ, producing important chemical messengers - adipokines and cytokines (adipocytokines). The search for new adipocytokines or adipokines gained added fervour with the prospect of the reconciliation between cardiovascular diseases (CVDs), obesity and metabolic syndrome. The role these new chemical messengers play in inflammation, satiety, metabolism and cardiac function has paved the way for new research and theories examining the effects they have on (in this case) CVD. Adipokines are involved in a 'good-bad', yin-yang homoeostatic balance whereby there are substantial benefits: cardioprotection, promoting endothelial function, angiogenesis and reducing hypertension, atherosclerosis and inflammation. The flip side may show contrasting, detrimental effects in aggravating these cardiac parameters.

Lipoprotein-associated phospholipase A2 activity predicts cardiovascular events in high risk coronary artery disease patients

Objective

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is deemed to play a role in atherosclerosis and plaque destabilization as demonstrated in animal models and in prospective clinical studies. However, most of the literature is either focused on high-risk, apparently healthy patients, or is based on cross sectional studies. Therefore, we tested the hypothesis that serum Lp-PLA2 mass and activity are useful for predicting cardiovascular (CV) events over the coronary atherosclerotic burden and conventional risk factors in high-risk coronary artery disease patients.

Methods and Results

In a prospective cohort study of 712 Caucasian patients, who underwent coronary angiography and measurement of both Lp-PLA2 mass and activity at baseline, we determined incident CV events at follow-up after splitting the patients into a high and a low Lp-PLA2 mass and activity groups based on ROC analysis and Youden index. Kaplan-Meier and propensity score matching analysis were used to compare CV event-free survival between groups. Follow-up data were obtained in 75% of the cohort after a median of 7.2 years (range 1–12.7 years) during which 129 (25.5%) CV events were observed. The high Lp-PLA2 activity patients showed worse CV event-free survival (66.7% vs. 79.5%, p = 0.023) and acute coronary syndrome-free survival (75.4% vs. 85.6%, p = 0.04) than those in low Lp-PLA2 group.

Conclusions

A high Lp-PLA2 activity implies a worse CV prognosis at long term follow up in high-risk Caucasian patients referred for coronary angiography.

The effects of selective estrogen receptor modulator treatment following hormone replacement therapy on elderly postmenopausal women with osteoporosis

OBJECTIVES

A comparison between the atheroprotective and osteoprotective effects of the selective estrogen receptor modulator (SERM) raloxifene and those of hormone replacement therapy (HRT) has not been made in elderly women.

METHODS

A randomized prospective controlled trial was performed in a cohort of 32 elderly Japanese women with osteoporosis receiving HRT (estriol plus medroxyprogesterone) for more than 1 year. In 16 randomly selected subjects, HRT was changed to raloxifene therapy (60mg/day, 71.4±3.4 years, SERM group). The other 16 patients were continued on HRT (71.8±2.9 years, HRT group). As a control group, 14 subjects were enrolled, did not take any medications and were age-matched to experimental patients (72.5±3.3 years, control group). Plasma lipids, TNFα, adiponectin, NO metabolites (NOx:NO2(-) and NO3(-)), cyclicGMP and bone-mineral density (BMD) were evaluated at baseline and at 26 and 52 weeks after enrollment.

RESULTS

SERM (Raloxifene) increased high-density-lipoprotein cholesterol levels and tended to decrease low-density-lipoprotein cholesterol levels (P=0.058) compared with baseline. Adiponectin, NOx and cGMP levels were significantly increased after 6 months compared with baseline or the HRT group. TNFα was decreased by raloxifene. In control subjects, no significant changes were observed in any of these markers. Bone-mineral density was higher at baseline in the raloxifene and HRT groups than in the control group, and BMD increased 12 months after baseline in the HRT and control group.

CONCLUSION

SERM improved BMD and endothelial function in elderly postmenopausal women with osteoporosis who had received HRT, and these effects were comparable to or slightly stronger than those of HRT. Changes in adiponectin and TNFα may underlie the improvements in endothelial function, such as NO signaling.

Adiponectin and vulnerable atherosclerotic plaques

High-risk plaques that are vulnerable to rupture demonstrate distinct morphological characteristics. They are differentiated from the lesions responsible for stable coronary artery disease by their large necrotic cores, thin-inflamed fibrous caps, and positive remodeling. Adiponectin is an adipocytokine that is reduced in obesity and type 2 diabetes. Hypoadiponectinemia has been associated with an increased risk of coronary artery disease and acute coronary syndrome in several though not all studies. The involvement of adiponectin provides clues to the inflammatory and atherogenic mechanisms associated with pathological coronary disease progression.

Elevated plasma levels of apelin in children with type 1 diabetes mellitus

BACKGROUND

Apelin is a novel adipocytokine produced by white adipose tissue that binds the APJ receptor with high affinity. Insulin may have a role in regulation of apelin synthesis and secretion from the adipose tissue.

OBJECTIVE

To investigate blood apelin concentrations in children with type 1 diabetes mellitus (T1DM) and display association of apelin with adiponectin, body mass index (BMI), lipids and insulin sensitivity.

METHODS

Thirty patients with T1DM and 45 healthy controls were enrolled. Apelin levels were measured along with BMI, lipids, fasting plasma glucose, HbA1c and adiponectin levels.

RESULTS

Plasma apelin and adiponectin levels were significantly higher in the diabetic group when compared to controls. No correlation was found between the apelin blood concentrations and adiponectin, BMI, lipids and insulin sensitivity.

CONCLUSIONS

Children with T1DM have significantly increased circulating apelin levels when compared to healthy controls. However, no significant relation was found between the apelin and BMI, glucose, lipids and adiponectin levels, and also insulin sensitivity.

Plasma adiponectin concentration is associated with ambulatory daytime systolic blood pressure but not with the dipping status

The objective of this study was to analyse the relationship between the ambulatory blood pressure (ABP) measurement and plasma adiponectin levels in a population-based cohort. Non-hypertensive, non-diabetics from the Oulu Project Elucidating Risk of Atherosclerosis cohort aged 40-60 years with ABP measurement available in 226 men and 236 women were analysed. ABP was recorded using the fully automatic SpaceLabs 90207 oscillometric unit. Plasma adiponectin concentrations were assayed using the enzyme-linked immunosorbent assay method. Without adjustment the highest plasma adiponectin tertile was associated with the lowest ABP and office BP measurements (P from 0.025 to P<0.001, respectively). Only the association of plasma adiponectin concentration with systolic ABP was independent of other conventional risk factors (age, body mass index (BMI), waist, gender, insulin sensitivity index, smoking and alcohol consumption) for hypertension (P=0.017). No association was observed between systolic dipping pattern and adiponectin level. The plasma high adiponectin concentration is independently associated with low daytime systolic ABP value. The mechanisms may include effects on endothelial function and the sympathetic nervous system.

Association between insulin, leptin, adiponectin and blood pressure in youth

OBJECTIVE

To examine whether insulin, leptin and adiponectin are independent correlates of blood pressure (BP) in a large population-based sample of children and adolescents.

METHODS

We studied 655 boys and 667 girls aged 9, 13 and 16 years who participated in the Quebec Child and Adolescent Health and Social Survey, a province-wide school-based survey conducted in 1999.

RESULTS

Strong, positive univariate associations between BMI, insulin and leptin Z-scores, and both systolic and diastolic BP were found in both sexes. Adiponectin Z-scores were negatively associated with systolic BP in girls only. In multivariate analyses only BMI and insulin Z-scores were significantly associated with systolic BP. In boys, each 1 SD increase in BMI was associated with a 4 mmHg increase in mean systolic BP; each 1 SD increase in insulin was associated with a 1 mmHg increase in mean systolic BP. Only insulin Z-scores were independently associated with diastolic BP in both sexes. For each 1 SD increase in insulin, there was a 1 mmHg increase in mean diastolic BP in boys. Similar to systolic BP, the magnitude of the effect of insulin Z-scores on diastolic BP increased as a function of BMI Z-scores in girls.

CONCLUSION

Independently of BMI, insulin is a strong correlate of systolic and diastolic BP in youth. Although animal studies support a role for leptin and adiponectin in controlling BP, they are not independently associated with BP in youth.

Elevated plasma adiponectin and decreased plasma homocysteine and asymmetric dimethylarginine in children with type 1 diabetes

OBJECTIVE

Type 1 diabetes has a bad prognosis concerning the pathogenesis of cardiovascular diseases (CVD). The purpose of this study was to evaluate different possible new risk indices for CVD in children with type 1 diabetes.

MATERIAL AND METHODS

The present study included 30 children with diabetes (mean HbA1C 9.8%), aged between 4.7 and 18.6 years and with no clinical evidence of vascular complications, and 30 healthy subjects matched by sex, age and body mass index. Blood pressure was measured and blood samples were obtained for lipid profile, creatinine, glucose, high sensitive C-reactive protein (hsCRP), intercellular adhesion molecule-1 (ICAM-1), asymmetric dimethylarginine (ADMA), adiponectin and homocysteine.

RESULTS

Children with diabetes had significantly higher blood pressure, plasma hsCRP, ICAM-1, adiponectin levels and lower homocysteine, ADMA concentrations than their control subjects. In multivariate regression analysis, the best predictors for systolic blood pressure were diabetes group, plasma homocysteine concentration and BMI (Adj R(2) = 0.38, p<0.0001), and for diastolic blood pressure diabetes group and triglycerides level (Adj R(2) = 0.27, p<0.0001).

CONCLUSIONS

Children with diabetes, in view of their higher future risk of CVD, are characterized by a higher concentration of protective adiponectin and paradoxically lower blood concentrations of some other possible risk markers of atherosclerosis, i.e. ADMA and homocysteine compared to healthy children.

Association of adiponectin with procollagen type I carboxyterminal propeptide in non-diabetic essential hypertension

OBJECTIVE

The serum concentration of procollagen type I carboxyterminal propeptide (PICP) is a good marker for collagen deposition in hypertension. Increased collagen deposition was associated with myocardial fibrosis and increased arterial stiffness. A decreased adiponectin level is associated with increased atherosclerosis. The role of adiponectin and its relation to PICP in essential hypertension have rarely been studied before.

METHODS

We recruited 188 non-diabetic uncomplicated hypertensive patients (mean age: 41+/-7 years; 128 men). No patient had vascular complications or renal or liver diseases. Overnight fasting blood samples were collected to assess patient lipid profiles, blood sugar, insulin, high-sensitivity C-reactive protein (hsCRP), PICP and adiponectin. Carotid to radial pulse wave velocity (PWV) measured using tonometry was used as an index of arterial stiffness.

RESULTS

Adiponectin (r = -0.216, p = 0.003) and male gender (p<0.001) were independent determinants of PICP. Diastolic blood pressure (r = 0.422, p<0.001) and current smoking (p = 0.005) were independent determinants of PWV. PWV was significantly correlated with PICP (r = 0.156, p = 0.034). Adiponectin was significantly correlated with triglyceride (r = -0.276, p<0.001), high-density lipoprotein (r = 0.262, p<0.001), the homeostasis model assessment (HOMA) index (r = -0.220, p = 0.002), hsCRP (r = -0.207, p = 0.004) and the body mass index (BMI) (r = -0.202, p = 0.005). After compensation with possible confounding factors, adiponectin was still significantly correlated with PICP (beta = -0.196, p = 0.006).

CONCLUSION

Serum adiponectin may be a marker for metabolic syndrome in essential hypertension. Adiponectin was significantly negatively correlated with PICP. Metabolic syndrome probably plays an important role in increased collagen synthesis and arterial stiffness through the effects of decreased adiponectin in non-diabetic essential hypertension.

Plasma adiponectin for prediction of cardiovascular events and mortality in high-risk patients

CONTEXT

The prognostic value of plasma levels of adiponectin, an adipocytokine with antiatherogenic, antiinflammatory, and insulin-sensitizing effects, is contentious.

OBJECTIVE

The objective of the study was to investigate whether plasma adiponectin levels predict cardiovascular (CV) events and mortality in high-risk coronary artery disease (CAD) patients. DESIGN, SETTING, PARTICIPANTS, AND MAIN OUTCOME MEASURE: We measured plasma adiponectin and examined its impact on the incidence of CV deaths and events at follow-up in the context of all potentially relevant background covariates in 712 high-risk patients of the Genetic and ENvironmental factors in Coronary Atherosclerosis study who underwent coronary angiography for suspected CAD. Based on the population plasma adiponectin median (6.38 microg/ml, interquartile range 4.2-10.2), we split the patients in a high- and a low-plasma adiponectin subgroup. After a median follow-up of 3.8 years (interquartile range 3.3-4.3 yr), outcome data were obtained in 100% of the patients and 45 CV deaths (6.4%) were recorded. Kaplan-Meier analysis unexpectedly showed a higher CV death rate in high-plasma adiponectin than low-plasma adiponectin patients. By contrast, multivariate Cox regression analysis, in which potential confounders, including ongoing medical treatment, were considered, showed no impact of plasma adiponectin on CV death. Similar negative results were obtained using the propensity score that considered all relevant covariables and medical treatment rate, which differed between the high- and low-plasma adiponectin group.

CONCLUSIONS

In high-risk CAD patients, plasma adiponectin above the median (6.38 microg/ml) implies a paradoxical higher risk of CV death. However, when relevant covariates that differ between high- and low-plasma adiponectin groups are considered, this association wanes, indicating that the clustering of plasma adiponectin with other covariates can abolish its impact on CV prognosis.

Impaired adiponectin-AMPK signalling in insulin-sensitive tissues of hypertensive rats

AIMS

Adiponectin improves insulin sensitivity by decreasing lipid accumulation in insulin-sensitive tissues. The aim of this study was to investigate whether these effects are altered in hypertension.

MAIN METHODS

Adiponectin receptors (AdipoR1 and AdipoR2) and adiponectin-related enzymes were measured by real-time PCR and Western-blot in insulin-sensitive tissues of 10-week-old male spontaneously hypertensive rats (SHR). Intrahepatic and intramyocellular triglycerides were determined by enzymatic methods.

KEY FINDINGS

SHR showed overweight, dyslipidemia, glucose intolerance and insulin resistance. Circulating concentrations of adiponectin as well as the mRNA and protein expression of adiponectin in epididymal and subcutaneous fat depots were significantly increased in hypertensive rats. Adiponectin mRNA levels were strongly associated with PPARgamma mRNA levels in both epididymal (r=0.54, P<0.05) and subcutaneous (r=0.93, P<0.0001) fat. The expression of AdipoR1 and AdipoR2, acetyl-CoA carboxylase (ACC), as well as carnitine palmitoyl transferase 1 (CPT1), were increased in skeletal muscle of SHR. These changes were not observed in the liver of SHR. In addition, in spite of the hyperadiponectinemia, SHR showed similar activation of AMP-activated protein kinase (AMPK) and a lower phosphorylation degree of its downstream ACC in liver and skeletal muscle. Accordingly, SHR exhibited a significant increase in intrahepatic (approximately 40%) and intramyocellular (approximately 60%) lipid accumulation.

SIGNIFICANCE

These findings suggest that dysregulation of the adiponectin downstream effectors contributes to increased intrahepatic and intramyocellular triglycerides in SHR. Hyperadiponectinemia together with overexpression of adiponectin receptors in skeletal muscle may reflect a defective compensatory mechanism to overcome adiponectin resistance in hypertensive rats.

Adiponectin levels associated with the development of hypertension: a prospective study

Adiponectin is a recently discovered protein that seems to be exclusively secreted by adipocytes and is the most abundant adipose tissue-derived protein. While some recent studies have demonstrated an association between adiponectin levels and hypertension, these studies were cross-sectional in design, and the results have been inconsistent. Therefore we performed a prospective study to elucidate the role of adiponectin in the development of hypertension. The results of this study showed that serum adiponectin levels were significantly lower in hypertensive subjects than in normotensive subjects. Moreover, in logistic regression analysis, the subjects in the lowest quartile had a 3.72-fold higher risk than those in the highest quartile. Even after adjusting for potential confounding factors, this association was found to be significant. Low serum adiponectin levels were found to be independently associated with a higher risk for the development of hypertension. Our results therefore suggest that hypoadiponectinemia is a novel predictor of hypertension.

Homocysteine, left ventricular dysfunction and coronary artery disease: is there a link?

Experimental and observational studies support a role of plasma homocysteine levels (tHcy) in coronary artery disease (CAD). In the GENICA (Genetic and Environmental factors In Coronary Atherosclerosis) study, we found that high tHcy predicted cardiovascular mortality in hypertensive, but not in normotensive, patients independently of CAD and history of myocardial infarction. Moreover, despite not being associated with the coronary atherosclerotic burden, tHcy was inversely associated with left ventricular (LV) ejection fraction. This inverse relationship between LV systolic function and tHcy, which has been independently confirmed, might explain the association of tHcy with the risk of incident heart failure documented in the Framingham Heart Study. Thus, additional mechanistic investigation taking into consideration the effects of tHcy on LV function is necessary to further explore the potential therapeutic usefulness of tHcy lowering treatment in CAD.

The emerging role of adipokines as mediators of cardiovascular function: physiologic and clinical perspectives

Interest in the biology of white adipose tissue has increased dramatically since the discovery of leptin in 1994. The identification of the product of the gene obese (ob) threw light on the role of adipose tissue in the physiopathology of obesity-related diseases and spurred the identification of numerous other adipokines, many of a proinflammatory nature. It has become increasingly evident that white adipose tissue-derived cytokines mediate between obesity-related exogenous factors (nutrition and lifestyle) and the molecular events that lead to metabolic syndrome, inflammation, and cardiovascular diseases. Here we review recent adipokine research, with particular attention to the roles of adiponectin, leptin, resistin, visfatin, apelin, omentin, and chemerin in such conditions.

Low serum adiponectin is independently associated with both the metabolic syndrome and angiographically determined coronary atherosclerosis

BACKGROUND

We aimed at investigating serum adiponectin in patients with the metabolic syndrome (MetS), in patients with angiographically diagnosed coronary artery disease (CAD), and in patients who had both, the MetS and CAD.

METHODS

We enrolled 687 consecutive patients undergoing coronary angiography for the evaluation of CAD.

RESULTS

From our patients, 178 had neither the MetS (Adult Treatment Panel III definition) nor significant CAD (MetS-/CAD-), 91 had the MetS, but not significant CAD (MetS+/CAD-), 251 did not have the MetS but had significant CAD (MetS-/CAD+), and 167 had both, the MetS and significant CAD (MetS+/CAD+). Serum adiponectin was highest (12.1+/-8.3 microg/ml) in MetS-/CAD- subjects. It was significantly lower in MetS+/CAD- (9.5+/-7.3 microg/ml; p=0.001) and in MetS-/CAD+ patients (9.2+/-5.3 microg/ml; p<0.001) and lowest in MetS+/CAD+ patients (6.7+/-3.8 microg/ml) in whom it was significantly lower than in MetS-/CAD-, MetS+/CAD-, and MetS-/CAD+ patients (p<0.001 for all comparisons). In analysis of covariance the MetS and significant CAD proved associated with serum adiponectin in a mutually independent manner.

CONCLUSIONS

Low serum adiponectin is independently associated with both the MetS and coronary atherosclerosis.