The association of serum chemerin level with risk of coronary artery disease in Chinese adults

Chemerin is a novel biomarker of acute coronary syndrome but not of stable angina pectoris

BACKGROUND

Recent evidence demonstrated that the circulating adipokines were associated with the onset of acute coronary syndrome (ACS) including unstable angina pectoris (UAP) and acute myocardial infarction (AMI). As a novel adipokine, chemerin has been related to atherosclerosis and the presence of coronary artery disease. However, the plasma levels of chemerin in patients with ACS have yet to be investigated.

METHODS

Plasma levels of chemerin and adiponectin were measured by an enzyme-linked immunosorbent assay (ELISA) in 60 patients with stable angina pectoris (SAP), 60 patients with UAP, 60 patients with AMI and 40 control patients. Left ventricular end-diastolic diameter (LVEDD) and left ventricular ejection fraction (LVEF) were measured using a GE ViVid E7 ultrasonography machine, and the severity of coronary stenosis in patients was estimated with a Gensini coronary score following coronary angiography.

RESULTS

Plasma chemerin levels were significantly higher in ACS patients than in the control and SAP groups, while plasma adiponectin levels were significantly lower in ACS patients than the control group. A correlation analysis revealed that plasma chemerin levels were positively correlated with the levels of C-reactive protein (CRP) (r = 0.29, P < 0.01) and LVEDD (r = 0.27, P < 0.01) but negatively correlated with LVEF (r = -0.45, P < 0.01) and that plasma adiponectin levels were positively correlated with LVEF (r = 0.53, P < 0.01) but negatively correlated with CRP (r = -0.33, P < 0.01) and LVEDD (r = -0.30, P < 0.01). Although significant correlations between chemerin, adiponectin and BMI or the Gensini coronary score were found in patients with SAP, neither chemerin nor adiponectin was correlated with BMI and the Gensini coronary score in patients with ACS. Furthermore, both chemerin (OR 1.103, 95% CI 1.065 to 1.142; P = 0.001) and adiponectin (OR 0.871, 95% CI 0.776 to 0.970; P = 0.018) were independently associated with the presence of ACS.

CONCLUSIONS

Chemerin is a novel biomarker of acute coronary syndrome but not of stable angina pectoris.

Chemerin levels as predictor of acute coronary events: a case-control study nested within the veterans affairs normative aging study

OBJECTIVE

Chemerin is a recently identified adipocytokine that has been positively correlated with the presence and severity of coronary artery disease (CAD). However, no studies have examined circulating chemerin levels as a predictor of acute coronary syndrome (ACS). The purpose of this study is to evaluate whether chemerin levels predict the onset of ACS.

MATERIALS/METHODS

We studied 90 men whose serum had been collected at least 2 years before the development of ACS, and 162 controls matched with the cases in a 1:2 fashion for age and year of collection. The mean age of the cohort was 66.3±9.6 years (range 34-84 years). Serum chemerin levels were measured with a commercially available enzyme-linked immunosorbent assay.

RESULTS

Age was positively associated with chemerin levels (r=0.39, p<0.001). Logistic regression analysis, adjusting for years since blood collection, demonstrated a null association between chemerin levels and the odds ratio for development of ACS (OR: 0.99, 95% CI [0.99-1.001]). This association remained null after adjusting for age (OR: 0.99 95% CI [0.99-1.001]).

CONCLUSIONS

Although cross-sectional and case-control studies suggest a positive association between chemerin levels and CAD, we demonstrate that chemerin levels do not predict the development of ACS.

Evaluation of circulating adipokines and abdominal obesity as predictors of significant myocardial ischemia using gated single-photon emission computed tomography

Objective

Coronary artery disease (CAD) is associated with abdominal obesity and metabolic syndrome. Adipocytes secrete adipokines, including the newly discovered adipocyte fatty acid binding protein (A-FABP) and chemerin. Adipokines contribute to the pathogenesis of CAD. In patients with CAD, the presence of significant ischemia predicts adverse outcomes. It is unknown whether adipokines can be better predictors of the presence of significant myocardial ischemia than conventional risk factors. This study aimed to compare adipokines with clinical risk factors and abdominal obesity as predictive factors for significant myocardial ischemia.

Methods

One hundred and ninety-six adults with suspected, but unproven, CAD were consecutively enrolled. The main measures were clinical and biochemical parameters and stress myocardial perfusion imaging with gated myocardial perfusion single-photon emission computed tomography (SPECT), with computed tomography (CT) attenuation correction. The abdominal visceral fat area was examined using a hybrid SPECT/CT scanner. Serum levels of high-sensitivity C-reactive protein (hs-CRP) and adipokines (adiponectin, A-FABP, and chemerin) were evaluated.

Results

A-FABP levels correlated significantly with adiponectin, hs-CRP, body mass index, waist circumference, and visceral fat area. A-FABP was significantly associated with metabolic syndrome (OR 3.2, 95% CI 1.6–6.4, p = 0.001), significant myocardial ischemia (OR 1.9, 95% CI 1.0–3.4, p = 0.05), and stress lung-to-heart ratio (β = 0.03, p = 0.03) on SPECT. Chemerin was significantly associated with serum triglyceride levels but not with metabolic syndrome, significant ischemia, or stress lung-to-heart ratio on SPECT. A-FABP was better at detecting significant inducible ischemia than other biomarkers, although this was a modest improvement (area under ROC curve 0.579, 95% CI 0.46–0.69).

Conclusions

Serum A-FABP concentrations correlate significantly with visceral fat area, metabolic syndrome, and predicted significant myocardial ischemia on SPECT. This may help to more accurately assess CAD risk, especially in patients with metabolic syndrome.

Exercise-induced lowering of chemerin is associated with reduced cardiometabolic risk and glucose-stimulated insulin secretion in older adults

OBJECTIVE

To determine the effect of exercise on chemerin in relation to changes in fat loss, insulin action, and dyslipidemia in older adults.

PARTICIPANTS

Thirty older (65.9±0.9yr) obese adults (BMI:34.5±0.7kg/m2).

SETTING

Single-center, Cleveland Clinic.

DESIGN

Prospective clinical trial.

INTERVENTION

Twelve-weeks of exercise training (60minutes/day, 5day/week at ~85% HRmax). Subjects were instructed to maintain habitual nutrient intake.

MEASUREMENTS

Plasma chemerin was analyzed using an enzyme-linked immunosorbent assay. Peripheral and hepatic insulin sensitivity was assessed using a euglycemic-hyperinsulinic clamp with glucose kinetics. First-phase and total glucose-stimulated insulin secretion (GSIS) was calculated from an oral glucose tolerance test. Fasting blood lipids (cholesterol, triglycerides), total/visceral fat (dual-x-ray absorptiometry and computerized tomography) and cardiorespiratory fitness (treadmill test) were also tested pre and post intervention.

RESULTS

Exercise increased fitness and reduced total/visceral fat, blood lipids, and first-phase GSIS (P<0.05). Training also increased peripheral insulin sensitivity and lowered basal/insulin-related hepatic glucose production (P<0.01). The intervention reduced chemerin (87.1±6.0 vs. 78.1±5.8ng/ml; P=0.02), and the reduction correlated with decreased visceral fat (r=0.50, P=0.009), total body fat (r=0.42, P=0.02), cholesterol (r=0.38, P=0.04), triglycerides (r=0.36, P=0.05), and first-phase and total GSIS (r=0.39, P=0.03 and r=0.43, P=0.02, respectively).

CONCLUSIONS

Lower chemerin appears to be an important hormone involved in cardiometabolic risk and GSIS reduction following exercise in older adults.

Serum chemerin levels during normal human pregnancy

During gestation there are important changes in maternal metabolism and an increase in insulin resistance, coinciding with an increase in adiposity. Chemerin is an adipocytokine which is expressed and secreted in various tissues, including placenta, and may play an important role in metabolic regulation during pregnancy. The aim of this study was to determine serum levels of chemerin during gestation and compare them to other indicators of insulin resistance. A cross-sectional study was carried out analyzing serum chemerin levels of 20 pregnant women during three gestational periods, early, middle, and late (between the 10th and 14th, the 23rd and 26th, and the 34th and 37th week) and 20 non-pregnant women were used as a control group. An analysis of chemerin levels during the menstrual cycle was performed in an eumenorrheic group (n=16) in the early follicular (cycle day 4±1) and the midluteal phase (cycle day 22±1), demonstrating that serum chemerin levels did not fluctuate significantly. Serum levels of chemerin were significantly elevated during late gestation when compared to early (P<0.001) and middle (P=0.001) gestation and a negative correlation between serum chemerin and adiponectin levels (r=-0.1643) became more significant when the non-pregnant group was included in the calculations (r=-0.2471). There was no significant association of triglycerides, total cholesterol, LDL, HDL, insulin, and HOMA levels with chemerin. Although chemerin rose significantly and is negatively associated with adiponectin levels, it is not correlated with other markers of insulin sensitivity, suggesting that more study is needed to determine whether chemerin is useful in predicting insulin resistance during gestation.

Towards an integrative approach to understanding the role of chemerin in human health and disease

Chemerin is an adipocyte-secreted protein with autocrine/paracrine roles on adipose development and function as well as endocrine roles in metabolism and immunity. Following prochemerin secretion, protease-mediated generation of chemerin isoforms with a range of biological activities is a key regulatory mechanism controlling local, context-specific chemerin bioactivity. Together, experimental and clinical data indicate that localized and/or circulating chemerin expression and activation are elevated in numerous metabolic and inflammatory diseases including psoriasis, obesity, type 2 diabetes, metabolic syndrome and cardiovascular disease. These elevations are positively correlated with deleterious changes in glucose, lipid, and cytokine homeostasis, and may serve as a link between obesity, inflammation and other metabolic disorders. This review highlights the current state of knowledge regarding chemerin expression, processing, biological function and relevance to human disease, particularly with respect to adipose tissue development, inflammation, glucose homeostasis and cardiovascular disease. Furthermore, it discusses study variability, deficiencies in current measurement, and questions concerning chemerin function in disease, with a special emphasis on techniques and tools used to properly assess chemerin biology. An integration of basic and clinical research is key to understanding how chemerin influences disease pathobiology, and whether modulation of chemerin levels and/or activity may serve as a potential method to prevent and treat metabolic diseases.

Elastase and tryptase govern TNFα-mediated production of active chemerin by adipocytes

Chemerin is a leukocyte chemoattractant and adipokine with important immune and metabolic roles. Chemerin, secreted in an inactive form prochemerin, undergoes C-terminal proteolytic cleavage to generate active chemerin, a ligand for the chemokine-like receptor-1 (CMKLR1). We previously identified that adipocytes secrete and activate chemerin. Following treatment with the obesity-associated inflammatory mediator TNFα, unknown adipocyte mechanisms are altered resulting in an increased ratio of active to total chemerin production. Based on these findings we hypothesized adipocytes produce proteases capable of modifying chemerin and its ability to activate CMKRL1. 3T3-L1 adipocytes expressed mRNA of immunocyte and fibrinolytic proteases known to activate chemerin in vitro. Following treatment with a general protease inhibitor cocktail (PIC), the TNFα-stimulated increase in apparent active chemerin concentration in adipocyte media was amplified 10-fold, as measured by CMKLR1 activation. When the components of the PIC were investigated individually, aprotinin, a serine protease inhibitor, blocked 90% of the TNFα-associated increase in active chemerin. The serine proteases, elastase and tryptase were elevated in adipocyte media following treatment with TNFα and their targeted neutralization recapitulated the aprotinin-mediated effects. In contrast, bestatin, an aminopeptidase inhibitor, further elevated the TNFα-associated increase in active chemerin. Our results support that adipocytes regulate chemerin by serine protease-mediated activation pathways and aminopeptidase deactivation pathways. Following TNFα treatment, increased elastase and tryptase modify the balance between activation and deactivation, elevating active chemerin concentration in adipocyte media and subsequent CMKLR1 activation.

Chemerin: a potential endocrine link between obesity and type 2 diabetes

Obesity and type 2 diabetes have reached epidemic levels and account for a substantial portion of the annual health expenditures of developed nations. While there is an abundance of epidemiological evidence demonstrating that obesity is a primary risk factor for developing type 2 diabetes, the mechanism(s) underlying this linkage are not completely understood. Given the enormous impact of these disorders on global health, considerable research effort has been devoted to elucidate the pathophysiological relationship between these two disorders. Two factors believed to contribute to the causal link between obesity and type 2 diabetes are chronic inflammation and altered secretion of adipose-derived signaling molecules (adipokines). Independent lines of investigation have implicated the novel adipokine chemerin as a regulator of adipogenesis, inflammation, and glucose metabolism through interactions with the cognate cell surface receptor chemokine-like receptor 1. Increased levels of chemerin that occur with obesity are hypothesized to be a causal factor in the development of type 2 diabetes as a consequence of dysregulation of the key physiological processes regulated by this adipokine. This review summarizes current research on the biological roles of chemerin and chemokine-like receptor 1, and highlights key questions to guide future research on the role of this adipokine in mediating obesity and the development of type 2 diabetes.

Potential association between coronary artery disease and the inflammatory biomarker YKL-40 in asymptomatic patients with type 2 diabetes mellitus

Background

Inflammation plays an important role in coronary artery disease from the initiation of endothelial dysfunction to plaque formation to final rupture of the plaque. In this study, we investigated the potential pathophysiological and clinical relevance of novel cytokines secreted from various cells including adipocytes, endothelial cells, and inflammatory cells, in predicting coronary artery disease (CAD) in asymptomatic subjects with type 2 diabetes mellitus.

Methods

We enrolled a total of 70 asymptomatic type 2 diabetic patients without a documented history of cardiovascular disease, and determined serum levels of chemerin, omentin-1, YKL-40, and sCD26. We performed coronary computed tomographic angiography (cCTA) in all subjects, and defined coronary artery stenosis ≥ 50 % as significant CAD in this study.

Results

Subjects were classified into two groups: patients with suspected coronary artery stenosis on cCTA (group I, n = 41) and patients without any evidence of stenosis on cCTA (group II, n = 29). Group I showed significantly higher YLK-40 levels and lower HDL-C levels than group II (p = 0.038, 0.036, respectively). Levels of chemerin, omentin-1, and sCD26 were not significantly different between the two groups. Serum YKL-40 levels were positively correlated with systolic/diastolic BP, fasting/postprandial triglyceride levels, and Framingham risk score. Furthermore, YKL-40 levels showed moderate correlation with the degree of coronary artery stenosis and the coronary artery calcium score determined from cCTA. In multivariate logistic analysis, after adjusting for age, gender, smoking history, hypertension, and LDL-cholesterol, YLK-40 levels showed only borderline significance.

Conclusions

YKL-40, which is secreted primarily from inflammatory cells, was associated with several CVD risk factors and was elevated in type 2 diabetic patients with suspected coronary artery stensosis on cCTA. These results suggest the possibility that the inflammatory biomarker YKL-40 might be associated with coronary artery disease in asymptomatic patients with type 2 diabetes mellitus.