Serum chemerin levels are associated with the presence and extent of coronary artery disease

Association of plasma chemerin with all-cause and disease-specific mortality - results from a population-based study

BACKGROUND AND OBJECTIVES

Various cross-sectional studies have observed an association between high circulating concentrations of the adipokine chemerin and an unfavorable metabolic profile. However, the prognostic value of chemerin for the risk of associated diseases and mortality was examined only in a few studies mostly using small and highly selected patient populations. We aimed to analyze the association between plasma chemerin concentrations and all-cause as well as cause-specific mortality in the general population.

STUDY DESIGN AND METHODS

From the Study of Health in Pomerania (SHIP), participants of two independent cohorts (SHIP-START-1 [n = 3037], SHIP-TREND-0 [n = 4193]) were followed up for 15 and 9 years (median), respectively. The association between plasma chemerin and all-cause mortality was analyzed using multivariable Cox proportional hazard regression models. Additionally, cause-specific hazards for cardiovascular disease (CVD) and cancer mortality were modeled considering competing events.

RESULTS

A total number of 507 and 208 deaths occurred during follow-up in SHIP-START-1 and SHIP-TREND-0, respectively. Multivariable regression analyses revealed a significant association between high plasma chemerin concentrations and greater overall mortality that was independent of major confounders. Each 30 ng/mL increase in chemerin was associated with a 17% higher risk of all-cause mortality (95%-confidence interval: 1.10-1.26). Cause-specific analyses further showed that the chemerin concentration was significantly associated with cancer mortality but not with CVD mortality.

CONCLUSION

The present study detected a positive association between plasma chemerin concentrations and all-cause mortality in a large population-based study sample. Cause-specific analyses have shown that chemerin is likely to play a decisive role in cancer-related deaths. However, a direct association with cardiovascular mortality could not be established.

The Role of Chemerin in Metabolic and Cardiovascular Disease: A Literature Review of Its Physiology and Pathology from a Nutritional Perspective

Chemerin is a novel adipokine that plays a major role in adipogenesis and lipid metabolism. It also induces inflammation and affects insulin signaling, steroidogenesis and thermogenesis. Consequently, it likely contributes to a variety of metabolic and cardiovascular diseases, including atherosclerosis, diabetes, hypertension and pre-eclampsia. This review describes its origin and receptors, as well as its role in various diseases, and subsequently summarizes how nutrition affects its levels. It concludes that vitamin A, fat, glucose and alcohol generally upregulate chemerin, while omega-3, salt and vitamin D suppress it. Dietary measures rather than drugs acting as chemerin receptor antagonists might become a novel tool to suppress chemerin effects, thereby potentially improving the aforementioned diseases. However, more detailed studies are required to fully understand chemerin regulation.

The Role of Adipokines in the Pathogenesis of Psoriasis

Psoriasis is a chronic and immune-mediated skin condition characterized by pro-inflammatory cytokines and keratinocyte hyperproliferation. Dendritic cells, T lymphocytes, and keratinocytes represent the main cell subtypes involved in the pathogenesis of psoriasis, while the interleukin-23 (IL-23)/IL-17 pathway enhances the disease progression. Human adipose tissue is an endocrine organ, which secretes multiple proteins, known as adipokines, such as adiponectin, leptin, visfatin, or resistin. Current evidence highlights the immunomodulatory roles of adipokines, which may contribute to the progression or suppression of psoriasis. A better understanding of the complexity of psoriasis pathophysiology linked with adipokines could result in developing novel diagnostic or therapeutic strategies. This review aims to present the pathogenesis of psoriasis and the roles of adipokines in this process.

Relationship between circulating adipokines and cholesterol efflux in subjects with severe carotid atherosclerosis

AIMS

Cholesterol efflux capacity (CEC) as a measure of high-density lipoprotein functionality is independently and inversely associated with increased risk of cardiovascular events and mortality, and advanced plaque morphology. Adipokines, adipose tissue-derived factors, can influence systemic lipoprotein metabolism, and participate in the regulation of vascular function and inflammation. We aimed to investigate the association between CEC and circulating adipokine levels (anti-inflammatory adiponectin, and pro-inflammatory chemerin and resistin) in subjects with severe carotid atherosclerotic disease and evaluate its impact on post-surgical outcomes.

METHODS AND RESULTS

This is a cross-sectional study with a 5-year follow-up component. Consecutive patients with severe carotid atherosclerosis scheduled for a carotid endarterectomy were recruited from hospital-based centres in Montreal, Canada (n = 285). Fasting blood samples were collected pre-operatively and used to measure plasma total and high-molecular weight (HMW) adiponectin, chemerin, and resistin, and to perform cholesterol efflux assays in J774 macrophage-like cells. Five-year post-surgery outcomes were obtained through medical chart review. Subjects had a mean age of 70.1 ± 9.4, were 67.0 % male, had various comorbidities (hypercholesterolemia [85.3 %], hypertension [83.5 %], type 2 diabetes [34.5 %], coronary artery disease [38.6 %]), and previously experienced cerebrovascular symptomatology (77.9 %). CEC was independently and positively associated with total and HMW adiponectin levels (ß [95 % confidence interval]; 0.216 [0.134-0.298] and 0.107 [0.037-0.176], respectively) but not with chemerin or resistin. Total adiponectin had the greatest association accounting for 8.3 % of the variance in CEC. Interaction regression models demonstrated a significant interaction between adiponectin and chemerin in increasing CEC. Notably, with each unit increase in CEC there was a 93.9 % decrease in the odds of having an ischemic cerebrovascular event 5 years post-surgery (0.061 [0.007-0.561]).

CONCLUSIONS

Our findings demonstrated circulating adiponectin to have a strong association with increased CEC in subjects with severe carotid atherosclerosis and high CEC to be associated with more favourable post-surgical outcomes. These findings reflect the importance of adipose tissue health in influencing CEC levels and atherosclerotic cardiovascular disease risk.

Causal Associations Between Circulating Adipokines and Cardiovascular Disease: A Mendelian Randomization Study

CONTEXT

Observational studies have suggested associations between adipokines and cardiovascular disease (CVD), but the roles of certain adipokines remain controversial, and these associations have not yet been ascertained causally.

OBJECTIVE

To investigate whether circulating adipokines causally affect the risk of CVD using 2-sample Mendelian randomization (MR).

METHODS

Independent genetic variants strongly associated with adiponectin, resistin, chemerin, and retinol binding protein 4 (RBP4) were selected from public genome-wide association studies. Summary-level statistics for CVD, including coronary artery disease (CAD), myocardial infarction, atrial fibrillation (AF), heart failure (HF), and stroke and its subtypes were collected. The inverse-variance weighted and Wald ratio methods were used for the MR estimates. The MR pleiotropy residual sum and outlier, weighted median, MR-Egger, leave-one-out analysis, MR Steiger, and colocalization analyses were used in the sensitivity analysis.

RESULTS

Genetically predicted resistin levels were positively associated with AF risk (odds ratio [OR] 1.09; 95% confidence interval [CI], 1.04-1.13; P = 4.1 × 10-5), which was attenuated to null after adjusting for blood pressure. We observed suggestive associations between higher genetically predicted chemerin levels and an increased risk of CAD (OR 1.27; 95% CI, 1.01-1.60; P = 0.040), higher genetically predicted RBP4 levels and an increased risk of HF (OR 1.14; 95% CI, 1.02-1.27; P = 0.024). There was no causal association between genetically predicted adiponectin levels and CVD risk.

CONCLUSIONS

Our findings reveal the causal association between resistin and AF, probably acting through blood pressure, and suggest potential causal associations between chemerin and CAD, RBP4, and HF.

Adipokines and Inflammation: Focus on Cardiovascular Diseases

It is well established that adipose tissue, apart from its energy storage function, acts as an endocrine organ that produces and secretes a number of bioactive substances, including hormones commonly known as adipokines. Obesity is a major risk factor for the development of cardiovascular diseases, mainly due to a low grade of inflammation and the excessive fat accumulation produced in this state. The adipose tissue dysfunction in obesity leads to an aberrant release of adipokines, some of them with direct cardiovascular and inflammatory regulatory functions. Inflammation is a common link between obesity and cardiovascular diseases, so this review will summarise the role of the main adipokines implicated in the regulation of the inflammatory processes occurring under the scenario of cardiovascular diseases.

Association of Serum Chemerin Levels with Coronary Artery Disease: Pathogenesis and Clinical Research

Recent studies have revealed that chemerin plays an essential role in the development of cardiovascular diseases. Autopsy studies found a strong correlation between the secretion of chemerin in peripheral tissues and aortic and coronary atherosclerosis. Plasma chemerin is a marker of systemic inflammation and is associated with metabolic syndrome. Chemerin plays a vital role in vascular inflammation and atherogenesis. Plasma chemerin levels are increased in patients with dilated cardiomyopathy, and chemerin is associated with left ventricular dysfunction. In this review, we focus on chemerin expression, chemerin processing, its biological function, and its role in the diagnosis of cardiovascular diseases.

Comparative effects of atorvastatin 80 mg and rosuvastatin 40 mg on the levels of serum endocan, chemerin, and galectin-3 in patients with acute myocardial infarction

Objective:

Endocan, chemerin, and galectin-3 are discrete biomarkers associated with cardiovascular diseases and acting through different pathophysiological pathways. The aim of this study is to investigate and compare the effects of high doses of atorvastatin and rosuvastatin on serum endocan, chemerin, and galectin-3 levels in patients with acute myocardial infarction (AMI).

Methods:

Sixty-three patients with AMI were randomized to receive atorvastatin (80 mg/day) or rosuvastatin (40 mg/day) after percutaneous revascularization. Serum levels of endocan, chemerin, and galectin-3 were evaluated at baseline and after 4-week therapy.

Results:

Endocan levels were not decreased statistically significantly with atorvastatin 80 mg, but rosuvastatin 40 mg markedly decreased the levels of endocan according to baseline [from 110.27 (86.03–143.69) pg/mL to 99.22 (78.30–122.87) pg/mL with atorvastatin 80 mg and from 110.73 (77.28–165.22) pg/mL to 93.40 (70.48–115.13) pg/mL with rosuvastatin 40 mg, p=0.242 for atorvastatin 80 mg and p=0.014 for rosuvastatin 40 mg]. Chemerin levels significantly decreased in both groups according to baseline [from 264.90 (196.00–525.95) ng/mL to 135.00 (105.95–225.65) ng/mL with atorvastatin 80 mg and from 309.95 (168.87–701.27) ng/mL to 121.25 (86.60–212.65) ng/mL with rosuvastatin 40 mg, p<0.001, respectively, for both groups]. Galectin-3 levels did not change markedly with atorvastatin 80 mg, but they decreased with rosuvastatin 40 mg [from 17.00 (13.10–22.25) ng/mL to 19.30 (15.25–23.45) ng/mL with atorvastatin 80 mg, p=0.721, and from 18.25 (12.82–23.82) ng/mL to 16.60 (10.60–20.15) ng/mL with rosuvastatin 40 mg, p=0.074]. There were no significant between-group differences in terms of absolute and percentage changes of endocan, chemerin, and galectin-3 at 4 weeks.

Conclusion:

We reported that both statins similarly decreased the endocan levels, whereas rosuvastatin seems to have more prominent effects on the reduction of the chemerin and galectin-3 levels in patients with AMI.

Chemerin-9, a potent agonist of chemerin receptor (ChemR23), prevents atherogenesis

Plasma levels of chemerin, an adipocytokine produced from the adipose tissues and liver, are associated with metabolic syndrome and coronary artery disease (CAD). Chemerin and its analog, chemerin-9, are known to bind to their receptor, ChemR23. However, whether chemerin and chemerin-9 affect atherogenesis remains to be elucidated. We investigated the expression of chemerin and ChemR23 in human coronary arteries and cultured human vascular cells. The effects of chemerin and chemerin-9 on atheroprone phenomena were assessed in human THP1 monocytes, human umbilical vein endothelial cells (HUVECs), and human aortic smooth muscle cells (HASMCs) and aortic lesions in Apoe−/− mice. In patients with CAD, a small amount of ChemR23, but not chemerin, was expressed within atheromatous plaques in coronary arteries. Chemerin and ChemR23 were expressed at high levels in THP1 monocytes, THP1-derived macrophages, and HUVECs; however, their expression in HASMCs was weak. Chemerin and chemerin-9 significantly suppressed the tumor necrosis factor-α (TNF-α)-induced mRNA expression of adhesion and pro-inflammatory molecules in HUVECs. Chemerin and chemerin-9 significantly attenuated the TNF-α-induced adhesion of THP1 monocytes to HUVECs and macrophage inflammatory phenotype. Chemerin and chemerin-9 suppressed oxidized low-density lipoprotein (oxLDL)-induced macrophage foam cell formation associated with down-regulation of CD36 and up-regulation of ATP-binding cassette transporter A1 (ABCA1). In HASMCs, chemerin and chemerin-9 significantly suppressed migration and proliferation without inducing apoptosis. In the Apoe−/− mice, a 4-week infusion of chemerin-9 significantly decreased the areas of aortic atherosclerotic lesions by reducing intraplaque macrophage and SMC contents. Our results indicate that chemerin-9 prevents atherosclerosis. Therefore, the development of chemerin analogs/ChemR23 agonists may serve as a novel therapeutic target for atherosclerotic diseases.

Serum Chemerin as a Novel Prognostic Indicator in Chronic Heart Failure

Background It has been documented that circulating chemerin is associated with inflammation, metabolic syndrome, and coronary artery disease. The present study was aimed to evaluate the prognostic value of serum chemerin in patients with chronic heart failure. Methods and Results We included 834 patients with chronic heart failure in a prospective cohort study and investigated the association between serum chemerin and clinical outcomes using multivariate Cox regression analysis. Patients with higher chemerin levels tended to be older and women and were more likely to experience hypertension, diabetes mellitus, and hyperlipemia. Cox regression analysis showed that chemerin was a significant predictor of major adverse cardiac events (hazard ratio, 1.83; 95% CI, 1.31-2.96) after adjustment for conventional risk factors. Net reclassification and integrated discrimination improvements for major adverse cardiac events were markedly improved by addition of chemerin to the reference model. In addition, chemerin was an independent predictor of all-cause mortality (hazard ratio, 1.67; 95% CI, 1.21-2.73) after multivariable adjustment. Furthermore, the Kaplan-Meier survival analysis revealed that chemerin was a prognostic indicator of major adverse cardiac events in patients with chronic heart failure and NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels above and below the median. Conclusions Our study suggests that chemerin is a novel serum marker for predicting major adverse cardiac events in patients with chronic heart failure.

Circulating Chemerin Levels, but not the RARRES2 Polymorphisms, Predict the Long-Term Outcome of Angiographically Confirmed Coronary Artery Disease

Chemerin, a novel adipokine, has been associated with metabolic, inflammatory, and atherosclerotic diseases. We aimed to determine the genetic basis of chemerin levels by conducting a genome-wide association study (GWAS) and to investigate the role of RARRES2 polymorphisms and circulating chemerin levels in the long-term outcome of coronary artery disease (CAD). A total of 2197 participants from the Taiwan Biobank (TWB) were recruited for the GWAS analysis, and 481 patients with angiographically confirmed CAD were enrolled for long-term outcome analysis. One locus of genome-wide significance with a single independent association signal was identified in the GWAS for chemerin levels with the peak association at the RARRES2 gene promoter region polymorphism rs3735167 (p = 2.35 × 10⁻²¹). In the CAD population, borderline significance was noted between RARRES2 polymorphisms and chemerin levels, whereas high chemerin levels were associated with obesity, female sex, diabetes mellitus, hypertension, current smoking, high platelet and leukocyte counts, anemia, impaired renal function, high C-reactive protein (CRP) levels, and multi-vessel disease. Kaplan–Meier survival curves indicated that the patients with high chemerin and CRP levels, but not those with RARRES2 polymorphisms, had a lower survival rate and higher combined cerebral and cardiovascular event rates. Combined chemerin and CRP levels further revealed a stepwise increase in poor clinical outcomes from low- to high-risk subgroups. In conclusion, rs3735167 is the lead RARRES2 polymorphism for chemerin levels in Taiwanese. Chemerin levels, but not the rs3735167 genotypes, predicted the long-term outcome of CAD, especially when combined with CRP levels.

Impact of arsenic exposure on clinical biomarkers indicative of cardiovascular disease risk in Mexican women

An appropriate and precise identification of high-risk individuals to develop cardiovascular diseases (CVD) is of high importance to reduce these kinds of diseases, a major health concern worldwide. Therefore, the aim of this research was to evaluate prognostic CVD biomarkers in Mexican women exposed to inorganic arsenic via drinking water. Then, a cross-sectional study including 190 women was achieved. Urinary arsenic (UAs) levels were analyzed as exposure biomarker to that metalloid. While, plasma asymmetric dimethylarginine (ADMA), adipocyte fatty acid-binding protein (FABP4), adiponectin, and chemerin levels, hypertriglyceridemic waist (HW) phenotype, atherogenic index of plasma (AIP), and Framingham risk score (FRS) were assessed as prognostic CVD biomarkers. Mean UAs level detected in the evaluated urinary samples was 45.0 ± 40.0 μg/g creatinine. In addition, mean plasma ADMA, FABP4, chemerin and adiponectin levels were 0.68 µmol/L, 20.3 ng/mL, 12.5 μg/mL, and 255 ng/mL, correspondingly. Approximately, 54% of women participants displayed an HW phenotype. Regarding AIP and FRS values, 0.12 ± 0.15 and 7.50 ± 8.00 were found, respectively. Besides, strong and significant associations (p < 0.05) between UAs and AIP, ADMA, and FABP4 were distinguished. Also, after a multivariate analysis, the association between those variables persisted after adjustment for traditional risk factors of CVD. In conclusion, according to the results found in this research, the most sensible CVD biomarkers distinguished in this study were AIP, ADMA, and FABP4. Nevertheless, more studies are necessary to confirm the results found in this investigation.

Association of Circulating Chemerin With Subclinical Parameters of Atherosclerosis: Results of a Population-Based Study

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Objective—

Chemerin has been shown to be associated with inflammation and metabolic syndrome, which are in turn leading risk factors for atherosclerosis. A few clinical studies have concentrated on the role of chemerin in atherosclerosis but revealed divergent findings. Therefore, we aimed to investigate the association of plasma chemerin levels with different subclinical measurements of atherosclerosis in a population-based sample.

Approach and Results—

Linear and logistic regression models with different atherosclerotic parameters as subclinical outcomes were applied to analyze data from 4003 subjects of the SHIP (Study of Health in Pomerania). After adjustment for metabolic and inflammatory parameters, these models revealed no association of chemerin with carotid intima-media thickness, carotid plaque, or carotid stenosis but a significant inverse association between chemerin and ankle-brachial index. In detail, logistic regression analysis showed that a 25-ng/mL increase in chemerin was associated with a 30% higher odd (95% confidence interval, 1.20–1.41) of having an ankle-brachial index value below the 25th age- and sex-specific quartile.

Conclusions—

Our analyses revealed a modest inverse association between chemerin and ankle-brachial index that remained consistent after adjustment for metabolic and inflammatory parameters. The association of chemerin with carotid intima-media thickness, carotid plaque, or carotid stenosis was not significant after adjustment for the same confounder set. The investigated subclinical atherosclerotic parameters are representative for the atherosclerotic burden of different arterial regions and different disease stages. Thus, our results might suggest that the value of chemerin as a marker of higher atherosclerotic risk differs depending on the affected arterial region and disease stage.

International Union of Basic and Clinical Pharmacology CIII: Chemerin Receptors CMKLR1 (Chemerin1) and GPR1 (Chemerin2) Nomenclature, Pharmacology, and Function

Chemerin, a chemoattractant protein and adipokine, has been identified as the endogenous ligand for a G protein–coupled receptor encoded by the gene CMKLR1 (also known as ChemR23), and as a consequence the receptor protein was renamed the chemerin receptor in 2013. Since then, chemerin has been identified as the endogenous ligand for a second G protein–coupled receptor, encoded by the gene GPR1. Therefore, the International Union of Basic and Clinical Pharmacology Committee on Receptor Nomenclature and Drug Classification recommends that the official name of the receptor protein for chemokine-like receptor 1 (CMKLR1) is chemerin receptor 1, and G protein–coupled receptor 1 is chemerin receptor 2 to follow the convention of naming the receptor protein after the endogenous ligand. Chemerin receptor 1 and chemerin receptor 2 can be abbreviated to Chemerin₁ and Chemerin₂, respectively. Chemerin requires C-terminal processing for activity, and human chemerin21–157 is reported to be the most active form, with peptide fragments derived from the C terminus biologically active at both receptors. Small-molecule antagonist, CCX832, selectively blocks CMKLR1, and resolvin E1 activation of CMKLR1 is discussed. Activation of both receptors by chemerin is via coupling to G_i/o, causing inhibition of adenylyl cyclase and increased Ca²⁺ flux. Receptors and ligand are widely expressed in humans, rats, and mice, and both receptors share ∼80% identity across these species. CMKLR1 knockout mice highlight the role of this receptor in inflammation and obesity, and similarly, GPR1 knockout mice exhibit glucose intolerance. In addition, the chemerin receptors have been implicated in cardiovascular disease, cancer, steroidogenesis, human immunodeficiency virus replication, and neurogenerative disease.

Association between chemerin, omentin-1 and risk of heart failure in the population-based EPIC-Potsdam study

The adipokines chemerin and omentin-1 have been suggested to influence cardiovascular function. The study aimed to investigate the longitudinal association between chemerin, omentin-1 concentrations and risk of incident heart failure (HF), respectively. We conducted a case-cohort study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam cohort (n = 27548) including a randomly drawn subsample and all incident HF cases during a mean follow-up of 8.2 ± 1.5 years. A total of 212 incident HF cases and 2168 individuals free of HF cases were included in the study. After multivariable adjustment for established cardiovascular risk factors chemerin was strongly associated with risk of HF (HR per doubling chemerin: 4.91; 95%-CI: 2.57-9.39; p < 0.0001). Omentin-1 was not significantly related to HF risk in the overall study population. However, the association between omentin-1 and HF risk was modified by prevalent coronary heart disease (CHD), showing that the shape of the association was linear in participants without prevalent CHD (HR doubling omentin-1: 2.11; 95%-CI: 1.36-3.27; p linear = 0.0009) and U-shaped in participants with pre-existing CHD (p non-linear = 0.006). Our study provides first evidence for a strong positive association between chemerin and risk of HF. The association between the adipokine omentin-1 and risk of HF may differ according to pre-existing CHD.

Tumor Necrosis Factor-Alpha and the ERK Pathway Drive Chemerin Expression in Response to Hypoxia in Cultured Human Coronary Artery Endothelial Cells

BACKGROUND

Chemerin, a novel adipokine, plays a role in the inflammation status of vascular endothelial cells. Hypoxia causes endothelial-cell proliferation, migration, and angiogenesis. This study was aimed at evaluating the protein and mRNA expression of chemerin after exposure of human coronary artery endothelial cells (HCAECs) to hypoxia.

METHODS AND RESULTS

Cultured HCAECs underwent hypoxia for different time points. Chemerin protein levels increased after 4 h of hypoxia at 2.5% O2, with a peak of expression of tumor necrosis factor-alpha (TNF-alpha) at 1 h. Both hypoxia and exogenously added TNF-alpha during normoxia stimulated chemerin expression, whereas an ERK inhibitor (PD98059), ERK small interfering RNA (siRNA), or an anti-TNF-alpha antibody attenuated the chemerin upregulation induced by hypoxia. A gel shift assay indicated that hypoxia induced an increase in DNA-protein binding between the chemerin promoter and transcription factor SP1. A luciferase assay confirmed an increase in transcriptional activity of SP1 on the chemerin promoter during hypoxia. Hypoxia significantly increased the tube formation and migration of HCAECs, whereas PD98059, the anti-TNF-alpha antibody, and chemerin siRNA each attenuated these effects.

CONCLUSION

Hypoxia activates chemerin expression in cultured HCAECs. Hypoxia-induced chemerin expression is mediated by TNF-alpha and at least in part by the ERK pathway. Chemerin increases early processes of angiogenesis by HCAECs after hypoxic treatment.

Association of serum chemerin concentrations with the presence of atrial fibrillation

Objective Chemerin, a newly discovered adipokine, is correlated with hypertension, diabetes and coronary heart disease. The aim of this study is to investigate the association of serum chemerin concentrations with the presence of atrial fibrillation. Methods Serum chemerin concentrations were determined in 256 patients with atrial fibrillation and 146 healthy subjects. Atrial fibrillation patients were then divided into paroxysmal, persistent and permanent atrial fibrillation. Results Serum chemerin concentrations were significantly higher in atrial fibrillation patients compared with healthy controls. In subgroup studies, patients with permanent atrial fibrillation had higher serum chemerin concentrations than those with persistent and paroxysmal atrial fibrillation. Furthermore, significant higher serum chemerin concentrations were observed in persistent atrial fibrillation patients compared with paroxysmal atrial fibrillation subjects. Serum chemerin concentrations were associated with the presence of atrial fibrillation after logistic regression analysis. Pearson correlation analysis revealed a positive relation of serum chemerin concentrations with body mass index, systolic blood pressure, diastolic blood pressure, triglycerides, low-density lipoprotein cholesterol, blood urea nitrogen, creatinine, C-reactive protein and left atrial diameter. Conclusion Serum chemerin concentrations are associated with the presence of atrial fibrillation and atrial remodelling.

Circulating Chemerin Is Associated With Carotid Plaque Instability, Whereas Resistin Is Related to Cerebrovascular Symptomatology

OBJECTIVE

The rupture of unstable carotid atherosclerotic plaques is one of the main causes of cerebrovascular ischemic events. There is need for circulating markers that can predict plaque instability and risk of stroke. Proinflammatory chemerin, leptin, and resistin, along with anti-inflammatory adiponectin, are adipokines with direct influence on vascular function. We investigated the association of circulating adipokines with carotid plaque instability and cerebrovascular symptomatology.

APPROACH AND RESULTS

Neurologically symptomatic and asymptomatic patients (n=165) scheduled for carotid endarterectomy were recruited. Fasting blood samples were collected preoperatively; adiponectin and leptin levels were determined by radioimmunoassay; and chemerin and resistin levels were measured by enzyme-linked immunosorbent assays. The instability of plaque specimens was assessed using gold-standard histological classifications. Chemerin was significantly associated with plaque instability. The fully adjusted model, accounting for age, sex, body mass index, high-sensitivity C-reactive protein, type 2 diabetes mellitus, and circulating adiponectin, leptin, and resistin, yielded an odds ratio of 0.991 (95% confidence interval 0.985-0.998) for plaque instability per unit increase in chemerin. High leptin levels were significantly associated with presence of specific features of plaque instability. In subjects with type 2 diabetes mellitus, resistin levels were significantly elevated in symptomatic when compared with asymptomatic subjects (P=0.001) and increased the risk of cerebrovascular symptomatology (adjusted odds ratio 1.264, 95% confidence interval 1.004-1.594).

CONCLUSIONS

Low chemerin and high resistin levels were associated with carotid disease severity, suggesting that these adipokines may act as potential markers for plaque instability and stroke risk. Future studies are needed to assess causation between circulating adipokines and plaque instability.

Chemerin as an independent predictor of cardiovascular event risk

Currently, coronary artery disease (CAD) is considered a major ailment in humans with widespread prevalence. CAD also accounts for high mortality rates around the world that involves several known risk factors. Chemerin is a novel adipokinine that is associated with inflammation and adipogenesis. Furthermore, experimental and clinical data indicate that localized as well as circulating chemerin expression and activation are elevated in numerous metabolic and inflammatory diseases including psoriasis, obesity, type 2 diabetes, metabolic syndrome and cardiovascular disease. Chemerin is accepted as being a strong marker because the serum chemerin levels are increased in a CAD condition. However, the chimeric characteristics of chemerin have not been fully investigated. Although chemerin is known to be responsible for CAD development among other factors, authors still investigate it at the marker level. This review focuses on chemerin expression, processing, biological function and relevance to human diseases, and on the role of chemerin in the maintenance of a cardiovascular disease.

Prenatal and Childhood Growth, Chemerin Concentrations, and Metabolic Health in Adult Life

Several noncommunicable diseases have their origins in early developmental phases. One factor possibly explaining the association between early growth and later health could be adipocyte function. The objective of this study was to assess the association between the adipocytokine chemerin and early growth and later health. 1074 participants from Helsinki Birth Cohort Study born 1934-1944 with information on prenatal and childhood growth participated. Metabolic outcomes include glucose tolerance, adiposity, and chemerin concentration. Mean chemerin concentrations were 5.0 ng/mL higher in women than in men (95% CI 2.7 to 7.2, p < 0.001). The strongest correlate of chemerin concentration was adult waist circumference and body fat percentage (r = 0.22, p < 0.001 and r = 0.21, p < 0.001, resp.). After adjustment for body fat percentage, chemerin concentration was 5.4 ng/mL lower in subjects with type 2 diabetes than in those with normal glucose tolerance (-0.2 to 10.9, p = 0.06). It was 3.0 ng/mL higher in those with metabolic syndrome than in those without (0.6 to 5.3, p = 0.01). No measure of early growth was associated with chemerin concentration. Our findings do not support a role for chemerin in linking early growth with later metabolic health.

Chemerin is not associated with subclinical atherosclerosis markers in prediabetes and diabetes

OBJECTIVE

Chemerin is a novel adipokine that is correlated with adipocyte differentiation, glucose metabolism, and inflammation. We aimed to investigate the relation between serum chemerin level and subclinical atherosclerosis markers as exemplified by brachial artery pulse wave velocity (baPWV), carotid intima-media thickness (CIMT), epicardial fat thickness (EFT), and carotid plaque presence in diabetes and prediabetes.

METHODS

Age-, body mass index (BMI)-, and gender-matched patients with type 2 DM (n=30), prediabetes (n=25), and normal glucose tolerance (n=25) were included in this cross-sectional study. Serum chemerin level, lipid parameters, glucose metabolism marker, baPWV, CIMT, EFT, and anthropometric were recorded. The independent risk factors for atherosclerosis markers were determined by linear and/or multiple logistic regression analysis.

RESULTS

baPWV and carotid plaque presence were higher in the diabetes group than in prediabetes and control groups (p=0.039 and p=0.035 respectively), whereas serum chemerin levels were similar among groups (p=0.338). Chemerin levels were not correlated with PWV, CIMT, and epicardial fat thickness overall or in the subgroups. Overall and in the diabetes group, chemerin levels were positively correlated with the key components of metabolic syndrome as BMI, total body fat percentage, waist circumference, triglyceride, and systolic and diastolic blood pressure (BP). After adjusting for age, gender, and BMI, only the association between chemerin and systolic BP remained significant. Chemerin was not found as an independent risk factor for predicting atherosclerosis in diabetes and prediabetes.

CONCLUSION

Chemerin is not a predictive marker for atherosclerosis in diabetes and prediabetes, but correlates well with key aspects of the metabolic syndrome particularly in diabetes.

High plasma chemerin is associated with renal dysfunction and predictive for cardiovascular events - Insights from phenotype and genotype characterization

The novel adipokine chemerin, encoded by the RARRES2 gene, has been suggested to be linked to insulin resistance and to the metabolic syndrome (MetS). However, no well-defined cardiovascular profile has been reported and the association with coronary artery disease (CAD) is a matter of debate. Because there is a relation between renal dysfunction and CAD, we analyzed plasma chemerin levels and the estimated glomerular filtration rate (eGFR) in 495 patients undergoing coronary angiography for the evaluation of established or suspected stable CAD. Chemerin levels were higher in patients with Type 2 diabetes mellitus (T2DM, n=111) and the metabolic syndrome (MetS, n=147) than in subjects without T2DM (191.5±72.9 vs. 169.7±64.7ng/ml, p=0.001) or the MetS (201.2±71.0 vs. 163,1ng/ml, p<0.001), but did not differ significantly between patients with significant CAD (n=247) and those without significant CAD (177.1±67.0 vs. 171.7±67.2ng/ml, p=0.193). Analysis of covariance using age, sex, and BMI as covariates showed that chemerin was significantly and independently associated with eGFR (F=49.6, p<0.001). After an 8-year follow-up period, patients with high chemerin levels were more often affected by cardiovascular events (HR=1.72 [95% CI 1.19-2.47], p=0.004), even after appropriate adjustment for age, gender, BMI, as well as eGFR (adjusted HR 1.51 [95% CI 1.03-2.23], p=0.037). Given the cardiometabolic role of chemerin, we also applied a Cardio-Metabo Chip analysis and revealed a genome-wide significant association with SNPs (rs55709438, rs2444030, and rs3098423) located at chromosomal region 15q15-23, which were associated with metabolic traits and eGFR. This study for the first time demonstrates that high chemerin concentrations are significantly associated with renal impairment and predictive of cardiovascular events and that 15q15-23 might have an impact on chemerin levels beyond common genetic variations in RARRES2.

Chemerin promotes the proliferation and migration of vascular smooth muscle and increases mouse blood pressure

Blood chemerin concentration shows positive correlation not only with body mass index and serum triglyceride level but also with systolic blood pressure. While it seems likely that chemerin influences vascular smooth muscle cell (SMC) proliferation and migration, which are crucial to the development of hypertension, this remains to be clarified. In the present study, we investigated whether chemerin controls SMC proliferation and migration in vitro and also affects blood pressure in vivo. In vitro, chemerin significantly stimulated rat mesenteric arterial SMC proliferation and migration, as determined by a cell counting assay and Boyden chamber assay, respectively. The migratory effect of chemerin was confirmed in human aortic SMCs. Chemerin significantly increased ROS production in SMCs and phosphorylation of Akt (Ser(473)) and ERK, as measured by fluorescent staining and Western blot analysis, respectively. Various inhibitors (ROS inhibitor: N-acetyl-l-cysteine, phosphatidylinositol 3-kinase inhibitor: LY-294002, MAPKK inhibitor: PD-98059, NADPH oxidase inhibitor: gp91 ds-tat, and xanthine oxidase inhibitor: allopurinol) as well as chemokine-like receptor 1 small interfering RNA significantly inhibited chemerin-induced SMC proliferation and migration. Furthermore, chemerin-neutralizing antibody prevented carotid neointimal hyperplasia in the mouse ligation model. In vivo, chronic chemerin treatment (6 μg/kg, 6 wk) increased systolic blood pressure as well as phosphorylation of Akt and ERK in the mouse isolated aorta. In summary, we, for the first time, demonstrate that chemerin/chemokine-like receptor 1 stimulates SMC proliferation and migration via ROS-dependent phosphorylation of Akt/ERK, which may lead to vascular structural remodeling and an increase in systolic blood pressure.

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.

Strong correlations between circulating chemerin levels and lipoprotein subfractions in nondiabetic obese and nonobese subjects

OBJECTIVE

Chemerin is a recently described adipokine expressed primarily in the white adipose tissue. Compared with lean subjects, circulating chemerin levels are significantly elevated in obese individuals and correlate positively with the prevalence of various cardiovascular risk factors including altered lipoprotein levels. To date, the impact of chemerin on lipoprotein subfractions and its role in atherosclerotic processes are still unclear.

PATIENTS AND METHODS

Fifty nondiabetic obese (NDO) patients and 38 lean controls matched in age and gender were enrolled. Chemerin level was measured by ELISA. Low-density lipoprotein (LDL) and high-density lipoprotein (HDL) subfractions were detected by nongradient polyacrylamide gel electrophoresis (Lipoprint).

RESULTS

We detected significantly higher serum chemerin levels in NDO patients compared with healthy controls (590·1 ± 190·3 ng/ml vs 405 ± 127·1 ng/ml, P < 0·001). A significant positive correlation was found between chemerin and LDL cholesterol levels, while chemerin showed a significant negative correlation with the level of HDL cholesterol. Significant positive correlation was detected between chemerin and the ratio of small dense LDL, while chemerin correlated negatively with the mean LDL size. Also, a significant negative correlation was found between serum chemerin and the ratio of large HDL subfraction, while there were significant positive correlations between chemerin levels and intermediate and small HDL subfraction ratios, respectively.

CONCLUSION

Chemerin may be involved in the regulation of lipoprotein metabolism in obese patients who do not show apparent abnormalities of glucose metabolism. Early changes in the distribution of the lipoprotein subfractions may contribute to the progression of atherosclerosis, leading to increased cardiovascular risk.

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.

Omentin and chemerin and their association with obesity in women with polycystic ovary syndrome

We aimed to investigate whether overweight/obesity is associated with omentin and chemerin. The study group consisted of 81 women with Polycystic ovarian syndrome (PCOS) (41 lean, BMI < 25 kg/m² and 40 overweight or obese, BMI > 25 kg/m²) and 61 healthy subjects (31 lean, BMI < 25 kg/m² and 30 overweight or obese, BMI > 25 kg/m²; control group). The clinical, endocrine, metabolic parameters, plasma omentin and chemerin levels were measured in patients and compared to control. In all subjects with PCOS (n = 80), serum chemerin levels were higher compared with those of the controls (n = 58) (7.71 ± 1.78 ng/mL versus 6.94 ± 0.82 ng/mL, p = 0.003). However, serum omentin levels were not significantly different between the PCOS subjects and the controls (1.55 ± 0.43 ng/mL versus 1.69 ± 0.37 ng/mL, p = 0.056). The mean chemerin concentrations were significantly elevated in the obese PCOS group compared with the obese control subjects (8.98 ± 1.45 ng/mL versus 7.02 ± 0.67 ng/mL, p = 0.000) and the nonobese PCOS group compared with the obese control subjects (6.57 ± 1.17 ng/mL versus 7.02 ± 0.67 ng/mL, p = 0.000). In conclusion, fat mass seems to be the main determinant factor of increased chemerin and decreased omentin in women with PCOS.

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.

Chemerin and CMKLR1 expression in human arteries and periadventitial fat: a possible role for local chemerin in atherosclerosis?

BACKGROUND

Depending on their anatomical location, different fat depots have a different capacity to produce bioactive peptides, called adipokines. Adipokines produced by periadventitial fat have been implicated in the pathogenesis of vascular disease, including atherosclerosis. Chemerin is an adipokine with an established role in immunity, adipose tissue function and metabolism, acting in autocrine, paracrine and endocrine manners. We investigated the protein expression of chemerin and its receptor, CMKLR1, in human aortas, coronary vessels and the respective periadventitial adipose tissue and correlated their expression with the presence of atherosclerosis.

METHODS

Immunohistochemistry for chemerin and CMKLR1 was performed on human aortic and coronary artery samples including the periadventitial adipose tissue. Aortic and coronary atherosclerotic lesions were assessed using the AHA classification.

RESULTS

Chemerin immunopositivity was noticed in both periadventitial fat depots, in vascular smooth muscle cells and foam cells in atherosclerotic lesions. Periadventitial fat and foam cell chemerin immunopositivity was statistically significantly correlated with the severity of atherosclerosis in both locations. CMKLR1 was expressed in vascular smooth muscle cells and foam cells in aortic and coronary vessels with atherosclerotic lesions. CMKLR1 immunostaining in foam cells was statistically significantly correlated with aortic atherosclerosis.

CONCLUSIONS

Our results lend some support to a presumable role of locally produced chemerin in the progression of atherosclerotic lesions, possibly acting through its CMKLR1 receptor. Further research will elucidate the role of chemerin signaling in atherosclerosis.

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.