Plasma chemerin level in metabolic syndrome

Obesity phenotypes and cardiovascular risk: From pathophysiology to clinical management

Obesity epidemic reached the dimensions of a real global health crisis with more than one billion people worldwide living with obesity. Multiple obesity-related mechanisms cause structural, functional, humoral, and hemodynamic alterations with cardiovascular (CV) deleterious effects. A correct assessment of the cardiovascular risk in people with obesity is critical for reducing mortality and preserving quality of life. The correct identification of the obesity status remains difficult as recent evidence suggest that different phenotypes of obesity exist, each one associated with different degrees of CV risk. Diagnosis of obesity cannot depend only on anthropometric parameters but should include a precise assessment of the metabolic status. Recently, the World Heart Federation and World Obesity Federation provided an action plan for management of obesity-related CV risk and mortality, stressing for the instauration of comprehensive structured programs encompassing multidisciplinary teams. In this review we aim at providing an updated summary regarding the different obesity phenotypes, their specific effects on CV risk and differences in clinical management.

Chemerin is resident to vascular tunicas and contributes to vascular tone

The adipokine chemerin may support blood pressure, evidenced by a fall in mean arterial pressure after whole body antisense oligonucleotide (ASO)-mediated knockdown of chemerin protein in rat models of normal and elevated blood pressure. Although the liver is the greatest contributor of circulating chemerin, liver-specific ASOs that abolished hepatic-derived chemerin did not change blood pressure. Thus, other sites must produce the chemerin that supports blood pressure. We hypothesize that the vasculature is a source of chemerin independent of the liver that supports arterial tone. RNAScope, PCR, Western blot analyses, ASOs, isometric contractility, and radiotelemetry were used in the Dahl salt-sensitive (SS) rat (male and female) on a normal diet. Retinoic acid receptor responder 2 (Rarres2) mRNA was detected in the smooth muscle, adventitia, and perivascular adipose tissue of the thoracic aorta. Chemerin protein was detected immunohistochemically in the endothelium, smooth muscle cells, adventitia, and perivascular adipose tissue. Chemerin colocalized with the vascular smooth muscle marker α-actin and the adipocyte marker perilipin. Importantly, chemerin protein in the thoracic aorta was not reduced when liver-derived chemerin was abolished by a liver-specific ASO against chemerin. Chemerin protein was similarly absent in arteries from a newly created global chemerin knockout in Dahl SS rats. Inhibition of the receptor Chemerin1 by the receptor antagonist CCX832 resulted in the loss of vascular tone that supports potential contributions of chemerin by both perivascular adipose tissue and the media. These data suggest that vessel-derived chemerin may support vascular tone locally through constitutive activation of Chemerin1. This posits chemerin as a potential therapeutic target in blood pressure regulation.NEW & NOTEWORTHY Vascular tunicas synthesizing chemerin is a new finding. Vascular chemerin is independent of hepatic-derived chemerin. Vasculature from both males and females have resident chemerin. Chemerin1 receptor activity supports vascular tone.

Nutritional Status and Selected Adipokines in Children with Irritable Bowel Syndrome

BACKGROUND

The aim of this study was to assess the nutritional status and serum concentrations of adipokines in children with irritable bowel syndrome (IBS) and healthy controls. We also sought to evaluate their relation to metabolic parameters.

METHODS

We studied 33 IBS patients (11 girls, 22 boys) aged 5-17 years and 30 healthy age-matched controls (11 girls, 19 boys). The analysis included anthropometric measurements, body composition parameter measurements using bioimpedance, and biochemical tests and measurements of serum concentrations of leptin, adiponectin, chemerin, and omentin-1.

RESULTS

The results of the anthropometric measurements were comparable between the patients and the controls. The patients had higher triglycerides, HOMA-IRs, and chemerin concentrations than the healthy subjects. The HDL cholesterol and omentin-1 levels were lower than in the controls. Leptin and adiponectin did not differ significantly between the groups. An analysis of the receiver operator curves (ROCs) showed that serum concentrations of chemerin ≥ 232.8 ng/mL had 30% sensitivity and 87% specificity when they were used to differentiate between children with IBS and healthy subjects. In the case of serum omentin-1 concentrations ≤ 279.4 ng/mL, the sensitivity and specificity were 60% and 80%, respectively.

CONCLUSIONS

The nutritional status of children with IBS did not differ from that of the healthy controls. We found significant differences in serum chemerin and omentin-1 concentrations between IBS patients and healthy children. These adipokines could be used as IBS biomarkers as they demonstrate good specificity and moderate sensitivity. The serum concentrations of chemerin and omentin-1 in IBS patients were related to nutritional status and insulin resistance.

Blood and Urinary Biomarkers of Antipsychotic-Induced Metabolic Syndrome

Metabolic syndrome (MetS) is a clustering of at least three of the following five medical conditions: abdominal obesity, high blood pressure, high blood sugar, high serum triglycerides, and low serum high-density lipoprotein (HDL). Antipsychotic (AP)-induced MetS (AIMetS) is the most common adverse drug reaction (ADR) of psychiatric pharmacotherapy. Herein, we review the results of studies of blood (serum and plasma) and urinary biomarkers as predictors of AIMetS in patients with schizophrenia (Sch). We reviewed 1440 studies examining 38 blood and 19 urinary metabolic biomarkers, including urinary indicators involved in the development of AIMetS. Among the results, only positive associations were revealed. However, at present, it should be recognized that there is no consensus on the role of any particular urinary biomarker of AIMetS. Evaluation of urinary biomarkers of the development of MetS and AIMetS, as one of the most common concomitant pathological conditions in the treatment of patients with psychiatric disorders, may provide a key to the development of strategies for personalized prevention and treatment of the condition, which is considered a complication of AP therapy for Sch in clinical practice.

Role of chemerin in the control of glucose homeostasis

Chemerin is an adipokine produced by the white adipose tissue and other tissues, which plays various roles in the pathogenesis of inflammatory and metabolic diseases in multiple organs. The present review aims at gathering scientific evidence reported in the last ten years, concerning the relationship of chemerin with alterations of glycaemic control, such as insulin resistance, type 2 diabetes and gestational diabetes in humans. Although the vast majority of the studies have shown a positive correlation between the chemerin level and a bad glycaemic control, a general consensus has not been reached. The reported results come from case-control and observational longitudinal studies, thereby limiting their interpretation. In fact, it cannot be stated whether insulin resistance and diabetes lead to an increase in chemerin levels or, on the contrary, if high levels of chemerin contribute to an impaired glycaemic control. Elevated levels of circulating chemerin are also associated with gestational diabetes mellitus. Chemerin gene polymorphisms could be proposed as mediators of glucose-related diseases. Nevertheless, to date very little is known about their implication in glucose metabolism. With regard to the mechanisms of action, chemerin impairs insulin cascade signaling by acting on several proteins of this cascade and by inducing inflammation.

Metabolic Syndrome: Updates on Pathophysiology and Management in 2021

Metabolic syndrome (MetS) forms a cluster of metabolic dysregulations including insulin resistance, atherogenic dyslipidemia, central obesity, and hypertension. The pathogenesis of MetS encompasses multiple genetic and acquired entities that fall under the umbrella of insulin resistance and chronic low-grade inflammation. If left untreated, MetS is significantly associated with an increased risk of developing diabetes and cardiovascular diseases (CVDs). Given that CVDs constitute by far the leading cause of morbidity and mortality worldwide, it has become essential to investigate the role played by MetS in this context to reduce the heavy burden of the disease. As such, and while MetS relatively constitutes a novel clinical entity, the extent of research about the disease has been exponentially growing in the past few decades. However, many aspects of this clinical entity are still not completely understood, and many questions remain unanswered to date. In this review, we provide a historical background and highlight the epidemiology of MetS. We also discuss the current and latest knowledge about the histopathology and pathophysiology of the disease. Finally, we summarize the most recent updates about the management and the prevention of this clinical syndrome.

Chemerin as a Driver of Hypertension: A Consideration

The protein chemerin (tazarotene-induced gene, TIG2; RARRES2) is a relatively new adipokine. Many studies support that circulating chemerin levels associate strongly and positively with body mass index, visceral fat, and blood pressure. Here, we focus on the specific relationship of chemerin and blood pressure with the goal of understanding whether and how chemerin drives (pathological) changes in blood pressure such that it could be interfered with therapeutically. We dissect the biosynthesis of chemerin and how current antihypertensive medications change chemerin metabolism. This is followed with a review of what is known about where chemerin is synthesized in the body and what chemerin and its receptors can do to the physiological function of organs important to blood pressure determination (e.g., brain, heart, kidneys, blood vessels, adrenal, and sympathetic nervous system). We synthesize from the literature our best understanding of the mechanisms by which chemerin modifies blood pressure, with knowledge that plasma/serum levels of chemerin may be limited in their pathological relevance. This review reveals several gaps in our knowledge of chemerin biology that could be filled by the collective work of protein chemists, biologists, pharmacologists, and clinicians.

Circulating chemerin level may be associated with early vascular pathology in obese children without overt arterial hypertension - preliminary results

Background Elevated chemerin level is observed in patients with arterial hypertension. The aim of the study was to determine the relationship between chemerin level, and parameters of blood pressure and arterial stiffness in children and adolescents with obesity but without arterial hypertension. Methods In 23 children with obesity (13 girls, mean age 9.3, SD 1.9, mean BMI SDS 3.9, SD 1.7) 24 h ABPM (Spacelabs 90,217, USA), common carotids and abdominal aorta intima media thickness measurements (Voluson 730, GE Medical System 8.5 and 3.5 MHz probes), body composition analysis (Tanita BC 418 S MA, Tokyo, Japan) were performed. Glucose, triglycerides, total, LDL and HDL cholesterol, liver enzymes, uric acid, creatinine, sodium, insulin and chemerin levels were assessed in blood sample taken after a 12-h fasting period. Results There was a significant correlation of circulating chemerin level with systolic blood pressure load in ABPM (r=0.5, p<0.05). Conclusion Elevated chemerin level may be associated with increased systolic blood pressure in obese children.

The associations among RARRES2 rs17173608 gene polymorphism, serum chemerin, and non-traditional lipid profile in patients with metabolic syndrome

Background

The adipokine chemerin retinoic acid receptor responder protein 2 (RARRES2) has been associated with insulin resistance, type II diabetes mellitus (T2DM), obesity, and metabolic syndrome (MetS). The impact of RARRES2 rs17173608 gene polymorphism on MetS and chemerin levels is not completely elucidated. This study included 100 patients with MetS and 68 healthy subjects (non-MetS group). The RARRES2 rs17173608 gene variant was analyzed by tetra amplification refractory mutation system polymerase chain reaction (T-ARMS-PCR). Circulating chemerin levels were determined by ELISA. Serum urea, creatinine, fasting blood glucose, glycated hemoglobin, and traditional lipid profile were measured by colorimetric methods. The estimated glomerular filtration rate (eGFR) and non-traditional lipid parameters were calculated.

Results

Serum chemerin levels were significantly higher in MetS than in non-MetS subjects, type II diabetics (T2DM) than non-diabetics, and overweight compared to lean subjects, but it did not differ significantly between patients with and without hypertension. Strikingly, newly diagnosed diabetic patients had significantly higher serum chermerin levels. Correlation and multiple linear regression analysis showed that serum chemerin levels and non-traditional lipid parameters were correlated significantly with the clinical criteria of MetS. Genotyping and allelic frequency distribution of RARRES2 rs17173608 gene polymorphism showed its significant association with MetS. The TT genotype of RARRES2 rs17173608 SNP was more distributed in T2DM in comparison with non-diabetics, and it was associated significantly with higher serum chemerin and higher glycated hemoglobin levels. RARRES2 rs17173608 GG genotype and G allele frequency were less distributed in T2DM patients than in non-diabetic patients.

Conclusions

The RARRES2 rs17173608 SNP might have an impact on chemerin levels and lipid parameters. The GG genotype and G allele may have a protective role towards the risk of T2DM but not for MetS. Serum chemerin and non-traditional lipid profile are significantly associated with MetS.

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.

The chemerin knockout rat reveals chemerin dependence in female, but not male, experimental hypertension

Measures of the adipokine chemerin are elevated in multiple cardiovascular diseases, including hypertension, but little mechanistic work has been done to implicate chemerin as being causative in such diseases. The chemerin knockout (KO) rat was created to test the hypothesis that removal of chemerin would reduce pressure in the normal and hypertensive state. Western analyses confirmed loss of chemerin in the plasma and tissues of the KO vs. wild-type (WT) rats. Chemerin concentration in plasma and tissues was lower in WT females than in WT males, as determined by Western analysis. Conscious male and female KO rats had modest differences in baseline measures vs. the WT that included systolic, diastolic, mean arterial and pulse pressures, and heart rate, all measured telemetrically. The mineralocorticoid deoxycorticosterone acetate (DOCA) and salt water, combined with uninephrectomy as a hypertensive stimulus, elevated mean and systolic blood pressures of the male KO higher than the male WT. By contrast, all pressures in the female KO were lower than their WT throughout DOCA-salt treatment. These results revealed an unexpected sex difference in chemerin expression and the ability of chemerin to modify blood pressure in response to a hypertensive challenge.-Watts, S. W., Darios, E. S., Mullick, A. E., Garver, H., Saunders, T. L., Hughes, E. D., Filipiak, W. E., Zeidler, M. G., McMullen, N., Sinal, C. J., Kumar, R. K., Ferland, D. J., Fink, G. D. The chemerin knockout rat reveals chemerin dependence in female, but not male, experimental hypertension.

Decrease in serum chemerin through aerobic exercise plus dieting and its association with mitigation of cardio-metabolic risk in obese female adolescents

BACKGROUND

The objective of this study was to determine the effects of a 4-week aerobic exercise plus dieting intervention on serum chemerin in obese female adolescents and its possible role in mitigating cardio-metabolic risk including glucose and lipid metabolism, central fat and inflammation.

METHODS

Fifty obese female adolescents were randomly divided into two groups: exercise plus dieting group (n=30) and dieting group (n=20). The participants in the exercise plus dieting group completed 4 weeks of moderate aerobic exercise combined with dieting, while the subjects in the dieting group undertook only dieting. Before and after the experiments, anthropometric index, parameters of glucose and lipid metabolism, serum chemerin and classic inflammatory indicators (C-reactive protein [CRP], tumor necrosis factor-α [TNF-α], interleukin-1β [IL-1β], IL-6, leptin and adiponectin) were measured.

RESULTS

Compared with the dieting group, a decrease in serum chemerin was found in the exercise plus dieting group, accompanied by significant improvements in anthropometric index, glucose and lipid metabolism and inflammatory factors. In addition, a higher serum chemerin level was found in obese adolescents with metabolic syndrome (MetS), and the disappearance of MetS induced by exercise plus dieting might be related to the decrease in chemerin. Correlation analysis showed the correlations of the decrease in chemerin with the changes in body fat, glucose and lipid metabolic index, leptin and adiponectin/leptin ratio.

CONCLUSIONS

This is the first report that as short a duration as 4-week aerobic exercise plus dieting decreased serum chemerin in obese female adolescents, which might be associated with the improvement in glucose and lipid metabolism, mitigation of inflammation and decrease in MetS incidence, thus lowering cardio-metabolic risk, while no health benefit resulted from slight dieting.

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.

Serum chemerin is associated with inflammatory and metabolic parameters-results of a population-based study

OBJECTIVE

This study aimed to confirm existing assumptions about the associations of circulating chemerin with inflammatory and metabolic parameters in a large population-based study.

METHODS

Data of 3,986 subjects from the Study of Health in Pomerania were analyzed. Residual method was used to investigate the different associations of visceral (VAT) and subcutaneous adipose tissue (SAT) with serum chemerin levels. Multivariable regression models were applied to examine the association of chemerin with high-sensitivity C-reactive protein, fibrinogen, glucose, glycated hemoglobin, lipid profile, blood pressure, diabetes, dyslipidemia, and hypertension.

RESULTS

Positive associations with chemerin were observed for VAT and SAT with a stronger relation found for VAT. After adjustment for waist circumference, increased chemerin levels were related to higher inflammatory cytokines and glycated hemoglobin and an unfavorable lipid profile. Logistic regression revealed positive associations of chemerin with dyslipidemia [highest vs. lowest quartile: odds ratio (OR) 1.56 (95% confidence interval (CI) 1.25-1.94)] and hypertension [OR 1.31 (95% CI 1.03-1.68)].

CONCLUSIONS

Chemerin levels are significantly linked to inflammation and metabolic syndrome. The majority of the detected associations persisted even after adjustment for waist circumference, suggesting that the relation of chemerin with the analyzed traits cannot be solely explained by an accumulation of adipose tissue.

Chemerin Elicits Potent Constrictor Actions via Chemokine-Like Receptor 1 (CMKLR1), not G-Protein-Coupled Receptor 1 (GPR1), in Human and Rat Vasculature

BACKGROUND

Circulating levels of chemerin are significantly higher in hypertensive patients and positively correlate with blood pressure. Chemerin activates chemokine-like receptor 1 (CMKLR1 or ChemR23) and is proposed to activate the "orphan" G-protein-coupled receptor 1 (GPR1), which has been linked with hypertension. Our aim was to localize chemerin, CMKLR1, and GPR1 in the human vasculature and determine whether 1 or both of these receptors mediate vasoconstriction.

METHODS AND RESULTS

Using immunohistochemistry and molecular biology in conduit arteries and veins and resistance vessels, we localized chemerin to endothelium, smooth muscle, and adventitia and found that CMKLR1 and GPR1 were widely expressed in smooth muscle. C9 (chemerin149-157) contracted human saphenous vein (pD2=7.30±0.31) and resistance arteries (pD2=7.05±0.54) and increased blood pressure in rats by 9.1±1.0 mm Hg at 200 nmol. Crucially, these in vitro and in vivo vascular actions were blocked by CCX832, which we confirmed to be highly selective for CMKLR1 over GPR1. C9 inhibited cAMP accumulation in human aortic smooth muscle cells and preconstricted rat aorta, consistent with the observed vasoconstrictor action. Downstream signaling was explored further and, compared to chemerin, C9 showed a bias factor=≈5000 for the Gi protein pathway, suggesting that CMKLR1 exhibits biased agonism.

CONCLUSIONS

Our data suggest that chemerin acts at CMKLR1, but not GPR1, to increase blood pressure. Chemerin has an established detrimental role in metabolic syndrome, and these direct vascular actions may contribute to hypertension, an additional risk factor for cardiovascular disease. This study provides proof of principle for the therapeutic potential of selective CMKLR1 antagonists.

Serum chemerin and high-sensitivity C reactive protein as markers of subclinical atherosclerosis in Egyptian patients with type 2 diabetes

CONTEXT

Chemerin is one of the adipokines that regulate fat metabolism. High-sensitivity C-reactive protein (hs-CRP) may be considered as a cardiovascular risk predictor. Measuring intima-media thickness of the CCA (C-IMT) is a well-evidenced tool for the detection of early stages of atherosclerosis. We aimed here to study both serum chemerin and hs-CRP as markers of subclinical atherosclerosis in Egyptian patients with type 2 diabetes, who are angiographically free of coronary artery disease (CAD).

SUBJECTS AND METHODS

This cross-sectional study was conducted on 180 subjects divided into two groups: Group A included 90 type 2 diabetic patients without CAD and group B including 90 nondiabetic control subjects. All study subjects were having normal coronary angiography. Serum chemerin, homeostasis model assessment for insulin resistance (HOMA-IR), glycated haemoglobin (HbA1c), lipid profile, hs-CRP as well as C-IMT were assessed in all study subjects.

RESULTS

There was a statistically significant difference between the 2 groups regarding serum chemerin level, HOMA-IR, hs-CRP and C-IMT; being higher in the diabetic patients than in the control group (p = 0.006, 0.024, 0.040 and <0.001, respectively). There was positive correlation between serum chemerin level and waist-to-hip ratio (WHR), HOMA-IR, hs-CRP and C-IMT. Carotid intima-media thickness was positively correlated with patients' WHR, blood pressure, HbA1c, diabetes duration as well as hs-CRP, and negatively correlated with ankle-brachial index (ABI). Linear regression analysis showed that HbA1c, serum chemerin and hs-CRP were independently affecting C-IMT. Serum hs-CRP was positively correlated with HbA1c and HOMA-IR (p = 0.006 and 0.032, respectively), and negatively correlated with HDL-cholesterol level (p = 0.018).

CONCLUSION

Both serum chemerin and hs-CRP could be considered as markers of subclinical atherosclerosis, and hence, may be utilized for the early detection of macrovascular disease, in Egyptian patients with type 2 diabetes.

Biomarkers of Metabolic Syndrome: Biochemical Background and Clinical Significance

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

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.

Association of Serum Chemerin Levels with Acute Ischemic Stroke and Carotid Artery Atherosclerosis in a Chinese Population

BACKGROUND

The aim of this study was to examine the association between serum level of chemerin with AIS and carotid artery atherosclerosis, and to investigate the level of chemerin as a potential novel cerebrovascular risk factor.

MATERIAL AND METHODS

We compared the serum chemerin levels and cerebrovascular parameters between 70 AIS patients and 70 non-AIS subjects in a Chinese population. Enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of serum chemerin. The state of carotid artery plaques in the AIS group was detected by color Doppler ultrasound. We used SPSS software for statistical analysis.

RESULTS

Compared with the non-AIS group, serum level of chemerin in the AIS group increased significantly (p<0.01). Multivariable logistic regression suggested that serum chemerin level, neutrophil count, and BMI were independent risk factors for AIS (p<0.05). Compared with the non-unstable plaque group, there were significant differences from the unstable plaque group in serum chemerin level (p<0.01). Multivariable logistic regression analysis revealed that the LDL-C, FIB, and serum chemerin levels were independent risk factors for carotid artery plaque instability (P<0.05). The levels of serum chemerin in the subjects with no carotid artery plaque were significantly lower than in those with carotid artery plaques of 2 and ≥3 (P=0.013; P=0.01).

CONCLUSIONS

The results of this study suggest that the serum chemerin level may be an independent risk factor for AIS and carotid artery plaque instability in Chinese populations.

Protective effect of liraglutide against ER stress in the liver of high-fat diet-induced insulin-resistant rats

The purpose of this study was to investigate whether the glucagon-like peptide-1 (GLP-1) analog liraglutide can alleviate endoplasmic reticulum (ER) stress and insulin resistance (IR) in the liver of high-fat diet-induced insulin-resistant rats. Eighty-five male Sprague-Dawley rats were fed with normal chow or a high-fat diet for 12 weeks. The IR was evaluated using the hyperinsulinemic-euglycemic clamp technique. The rats in the HF group were further divided into four groups and were treated with or without liraglutide by subcutaneous injection. Body weight (BW), fasting blood glucose (FBG), fasting insulin (FINS), and insulin sensitivity were measured. The expression of ER stress marker GRP78 and its signaling mediators, such as IRE1α, PERK, and ATF6, in the liver were examined. The ultrastructure of the ER in the liver was examined by transmission electron microscopy. The expression levels of chemerin in the liver and the serum were also measured. After 4 weeks of liraglutide treatment, the BW, FBG, and FINS levels were significantly reduced, and the insulin sensitivity was increased compared with the HF only rats. Liraglutide reduced the expression of GRP78 and chemerin in liver tissue at both the mRNA and protein levels. Interestingly, the chemerin mRNA was closely correlated with the level of GRP78 mRNA, while the level of chemerin in serum was also associated with the FINS level. As a representative GLP-1 analog, liraglutide can suppress ER stress and reduce chemerin expression in the liver of rats exposed to a high-fat diet.

Increased Serum Chemerin Levels in Diabetic Retinopathy of Type 2 Diabetic Patients

PURPOSE

To compare serum levels of chemerin in type 2 diabetes mellitus (T2DM) with or without retinopathy, and to investigate the relationship between serum chemerin levels and diabetes retinopathy.

MATERIALS AND METHODS

A total of 60 T2DM patients and 20 healthy subjects (control group) were enrolled in this study. Of the T2DM patients, 15 had proliferative diabetic retinopathy (PDR group), 20 had non-proliferative retinopathy (NPDR group) and 25 had no retinopathy (T2DM group). Their serum samples were collected for testing the levels of chemerin, vascular endothelial growth factor (VEGF), C-reactive protein (CRP) and so on. The values were analyzed to compare the differences among the groups. Simple linear regression analysis and multiple stepwise linear regression analysis were used to determine the correlations between variables and chemerin. Trend chi-square was used to determine the correlations between chemerin and the severity of diabetic retinopathy (DR).

RESULTS

Chemerin levels in group PDR, NPDR and no DR were 147.56 ± 35.98 μg/l, 128.09 ± 16.33 μg/l and 113.19 ± 19.89 μg/l, with the significant difference across the three groups (p < 0.05). But there was no difference between control group (109.55 ± 20.98 μg/l) and T2DM group. Simple linear regression show that serum chemerin was correlated with duration of diabetes, body mass index (BMI), serum triglycerides, total-cholesterol, CRP and VEGF, and not correlated with age, systolic and diastolic blood pressure in T2DM patients. Stepwise regression analysis showed that BMI, CRP and VEGF were significantly associated with serum chemerin (p = 0.006, p = 0.011 and p = 0.036, respectively). In addition, the more severity of DR as the chemerin levels increased (χ(2) = 16.07, p < 0.001).

CONCLUSIONS

Serum levels of chemerin were significantly increased in the NPDR and PDR group. Elevated serum level of chemerin and its positive correlation with BMI, CRP and VEGF suggested that chemerin was associated with obesity, inflammation and neovascularization and might be involved in the development of DR.

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.