Decreased serum chemerin levels in male Japanese patients with type 2 diabetes: sex dimorphism

Vascular effects of perivascular adipose tissue-derived chemerin in obesity-associated cardiovascular disease

Perivascular adipose tissue (PVAT) is a unique and metabolically active adipose tissue that is adjacent to most systemic blood vessels. Healthy PVAT exerts anticontractile and anti-inflammatory effects, contributing to vascular protection. However, during obesity, PVAT becomes proinflammatory and profibrotic, exacerbating vascular dysfunction. Chemerin, a multifunctional adipokine, has emerged as a key regulator of vascular tone, inflammation, and remodeling. Although liver-derived chemerin dominates the circulating chemerin pool, PVAT-derived chemerin plays a more localized and functionally important role in vascular pathophysiology because of its proximity to the vessel wall. This review highlights the role of PVAT-derived chemerin in vascular health, the mechanistic involvement of PVAT-derived chemerin in certain aspects of obesity-associated cardiovascular diseases, and the therapeutic potential of targeting PVAT-derived chemerin.

A Cross-Sectional Study: Systematic Quantification of Chemerin in Human Cerebrospinal Fluid

BACKGROUND

Dysregulation of adipokines is considered a key mechanism of chronic inflammation in metabolic syndrome. Some adipokines affect food intake by crossing the blood/brain barrier. The adipokine chemerin is associated with metabolic syndrome, cardiovascular diseases and immune response. Little is known about chemerin's presence in cerebrospinal fluid (CSF) and its ability to cross the blood/CSF barrier.

METHODS

We quantified chemerin levels in paired serum and CSF samples of 390 patients with different neurological diagnoses via enzyme-linked immunosorbent assay (ELISA). Correlation analyses of serum and CSF chemerin levels with anthropometric, serum and CSF routine parameters were performed.

RESULTS

Overweight patients exhibited higher chemerin levels in serum and CSF. Chemerin CSF levels were higher in men. Chemerin levels in serum were associated with BMI (body mass index) and CRP (C-reactive protein). Chemerin levels in CSF were associated with age. Neurological diseases affected chemerin levels in CSF. The chemerin CSF/serum ratio was calculated as 96.3 ± 36.8 × 10-3 for the first time.

CONCLUSIONS

Our data present a basis for the development of standard values for chemerin quantities in CSF. CSF chemerin levels are differentially regulated in neurological diseases and affected by BMI and sex. Chemerin is able to cross the blood/CSF barrier under physiological and pathophysiological conditions.

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.

Chemerin as an Inducer of β Cell Proliferation Mediates Mitochondrial Homeostasis and Promotes β Cell Mass Expansion

Loss of the β cell population is a crucial feature of type 2 diabetes. Restoring the β cell mass by stimulating β cell proliferation and preventing its apoptosis was proposed as a therapeutic approach to treating diabetes. Therefore, researchers have been increasingly interested in identifying exogenous factors that can stimulate β cell proliferation in situ and in vitro. Adipokine chemerin, which is secreted from adipose tissue and the liver, has been identified as a chemokine that plays a critical role in the regulation of metabolism. In this study, we demonstrate that chemerin as a circulating adipokine promotes β cell proliferation in vivo and in vitro. Chemerin serum levels and the expression of the main receptors within islets are highly regulated under a variety of challenging conditions, including obesity and type 2 diabetes. As compared to their littermates, mice overexpressing chemerin had a larger islet area and increased β cell mass with both a normal and high-fat diet. Moreover, in chemerin-overexpressed mice, we observed improved mitochondrial homeostasis and increased insulin synthesis. In summary, our findings confirm the potential role of chemerin as an inducer of β cell proliferation, and they provide novel insights into the helpful strategy to expand β cell population.

Chemerin Forms: Their Generation and Activity

Chemerin is the product of the RARRES2 gene which is secreted as a precursor of 143 amino acids. That precursor is inactive, but proteases from the coagulation and fibrinolytic cascades, as well as from inflammatory reactions, process the C-terminus of chemerin to first activate it and then subsequently inactivate it. Chemerin can signal via two G protein-coupled receptors, chem1 and chem2, as well as be bound to a third non-signaling receptor, CCRL2. Chemerin is produced by the liver and secreted into the circulation as a precursor, but it is also expressed in some tissues where it can be activated locally. This review discusses the specific tissue expression of the components of the chemerin system, and the role of different proteases in regulating the activation and inactivation of chemerin. Methods of identifying and determining the levels of different chemerin forms in both mass and activity assays are reviewed. The levels of chemerin in circulation are correlated with certain disease conditions, such as patients with obesity or diabetes, leading to the possibility of using chemerin as a biomarker.

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.

Interplay between adipose tissue secreted proteins, eating behavior and obesity

Purpose

Adipokines may play an important role in the complex etiology of human obesity and its metabolic complications. Here, we analyzed the relationship between 15 adipokines, eating behavior and body-mass index (BMI).

Methods

The study included 557 participants of the Sorbs (62.1% women, 37.9% men) and 3101 participants of the population-based LIFE-Adult cohorts (53.4% women, 46.4% men) who completed the German version of the Three-Factor-Eating Questionnaire to assess the eating behavior types cognitive restraint, disinhibition and hunger. Serum levels of 15 adipokines, including adiponectin, adipocyte fatty acid-binding protein (AFABP), angiopoietin-related growth factor (AGF), chemerin, fibroblast growth factor (FGF)-19, FGF-21, FGF-23, insulin-like growth factor (IGF)-1, interleukin (IL) 10, irisin, progranulin, vaspin, pro-neurotensin (pro-NT), pro-enkephalin (PENK) and leptin were measured. Based on significant correlations between several adipokines with different eating behavior items and BMI, we conducted mediation analyses, considering the eating behavior items as potential mediation variable towards BMI.

Results

Here, we found that the positive association between chemerin, AFABP or leptin and BMI in Sorbian women was mediated by higher restraint or disinhibited eating, respectively. Additionally, in Sorbian women, the negative relation between IGF-1 and BMI was mediated by higher disinhibition and the positive link between AGF and BMI by lower disinhibition. In Sorbian men, the negative relationship between PENK and BMI was mediated by lower disinhibition and hunger, whereas the negative relation between IGF-1 and BMI was mediated by higher hunger. In the LIFE-Adult women´s cohort, associations between chemerin and BMI were mediated by decreased hunger or disinhibition, respectively, whereas relations between PENK and BMI were fully mediated by decreased disinhibition.

Conclusion

Our study suggests that adipokines such as PENK, IGF-1, chemerin, AGF, AFABP and leptin might affect the development of obesity by directly modifying individual eating behavior. Given the observational nature of the study, future experimental or mechanistic work is warranted.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02687-w.

The Comparison of Predictive Value Among Chemerin, IL-18 and Hormonal Parameters in Assessing the Risk of Metabolic Syndrome in Men

Chemerin (CHEM) is a new proinflammatory adipokine involved in the immune, metabolic and reproductive processes. Low-grade state inflammation (LGSI) is a key element in the pathogenesis of metabolic syndrome (MS). Low SHBG is a good marker of male hypogonadism in MS. This study evaluated the prognostic value of selected adipokine, LGSI, and androgenic parameters in predicting the risk of MS among men. One hundred thirty-two random men aged 40 to 70 years old were enrolled. Measurements of anthropometric indices, blood pressure, and laboratory tests were carried out. A total of 62 men (47%) were diagnosed with MS. Chemerin concentrations were higher in men diagnosed with MS compared to healthy: 89.48 (78.12-112.10) vs. 77.9 (65.12-98.64) ng/mL; p = .002. Men diagnosed with MS presented with lower levels of total testosterone: 5.75 (4.00-6.57) vs. 6.40 (5.50-8.40) ng/mL; p = .0014 and SHBG: 46.58 (35.13-66.28) vs. 71.97 (56.1-92.7) nM/L; p < 0.000001. Elevated LGSI indices were demonstrated in men with MS as opposed to healthy [IL-18: 530.64 (409.12-640.56) vs. 418.85 (348.14-496.44) pg/mL; p = .000033 and hs-CRP: 2.15 (0.97-4.26) vs. 1.01 (0.41-2.68) ng/mL; p = .0057)]. In multivariate regression analysis, the highest negative predictive value in assessing the risk of MS was SHBG serum concentration, while the highest positive predictive values were: IL-18, hypertriglyceridemia, and waist circumference. Decreased SHBG levels, combined with elevated IL-18 concentrations in men showing hypertriglyceridemic waist phenotype, significantly increase the risk of MS.

Diabetes and Obesity-Cumulative or Complementary Effects On Adipokines, Inflammation, and Insulin Resistance

Background: Diabetes and obesity are increasingly significant public health issues. The aim of this study was to evaluate the relationship between adipocytokines (leptin, ghrelin, and chemerin), inflammation (sVCAM1—soluble vascular adhesion molecule 1, sICAM1—soluble intercellular adhesion molecule 1), and insulin resistance in the presence of obesity and diabetes mellitus. Methods: 88 subjects, with a mean age of 61.96 ± 10.15 years, 75% of whom were women, were evaluated (in order to consider different associations between obesity and diabetes, subjects were categorized into four groups). Results: Overall, we found significant correlations between sICAM1-sVCAM1 rho = 0.426 and ghrelin-chemerin rho = −0.224. In the obesity + diabetes group, leptin correlated with sICAM1 rho = 0.786, and sVCAM1 negatively with glycemia/insulin rho = −0.85. Significant differences were found between the groups regarding sVCAM1 (p = 0.0134), leptin (p = 0.0265) and all insulin resistance scores, with differences influenced by the subjects’ gender. In conclusion, although there are currently many unknown aspects of the release and the role of various adipokines, in particular chemerin, its implication in early glucose metabolism dysregulation disorders seems very likely.

Chemerin: a multifaceted adipokine involved in metabolic disorders

Metabolic syndrome is a global public health problem and predisposes individuals to obesity, diabetes and cardiovascular disease. Although the underlying mechanisms remain to be elucidated, accumulating evidence has uncovered a critical role of adipokines. Chemerin, encoded by the gene Rarres2, is a newly discovered adipokine involved in inflammation, adipogenesis, angiogenesis and energy metabolism. In humans, local and circulating levels of chemerin are positively correlated with BMI and obesity-related biomarkers. In this review, we discuss both peripheral and central roles of chemerin in regulating body metabolism. In general, chemerin is upregulated in obese and diabetic animals. Previous studies by gain or loss of function show an association of chemerin with adipogenesis, glucose homeostasis, food intake and body weight. In the brain, the hypothalamus integrates peripheral afferent signals including adipokines to regulate appetite and energy homeostasis. Chemerin increases food intake in seasonal animals by acting on hypothalamic stem cells, the tanycytes. In peripheral tissues, chemerin increases cell expansion, inflammation and angiogenesis in adipose tissue, collectively resulting in adiposity. While chemerin signalling enhances insulin secretion from pancreatic islets, contradictory results have been reported on how chemerin links to obesity and insulin resistance. Given the association of chemerin with obesity comorbidities in humans, advances in translational research targeting chemerin are expected to mitigate metabolic disorders. Together, the exciting findings gathered in the last decade clearly indicate a crucial multifaceted role for chemerin in the regulation of energy balance, making it a promising candidate for urgently needed pharmacological treatment strategies for obesity.

Low circulating chemerin levels correlate with hepatic dysfunction and increased mortality in decompensated liver cirrhosis

Nutritional status, infections, inflammation and extrahepatic organ dysfunction are critical factors for the progression of chronic liver disease. Chemerin is an immune-metabolically and chemotactically active adipokine and we hypothesized that it is associated with disease severity and prognosis in patients with advanced decompensated cirrhosis. Therefore, we measured serum concentrations of chemerin in a prospectively characterized cohort of 80 patients with decompensated cirrhosis and ascites and assessed the associations with markers of disease severity and short-term outcome at 28 days. In a subset of patients (n = 40), ascitic fluid chemerin was determined. Advanced liver disease was associated with decreased serum but not ascitic chemerin levels. Serum chemerin correlated with markers of hepatic function (total bilirubin, albumin, INR) and inversely correlated with indicators of portal hypertension (platelet count, gastrointestinal bleeding) but not with extrahepatic organ failure and systemic inflammation. Patients presenting with acute-on-chronic liver failure or infection did not exhibit altered serum or ascitic fluid chemerin concentrations. However, serum chemerin levels below 87 ng/ml predicted an increased risk for mortality or liver transplantation within 28 days independently of MELD and infections. We conclude that low serum chemerin is an independent adverse prognostic factor in patients with advanced decompensated cirrhosis.

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.

Challenges in Sex- and Gender-Centered Prevention and Management of Cardiovascular Disease: Implications of Genetic, Metabolic, and Environmental Paths

The recognition of cardiovascular disease (CVD) as a "male" privilege has been a commonly held concept. However, emerging data describe another reality. Heterogeneities have been convincingly demonstrated regarding CVD manifestations, risk factor burden, and prognosis between males and females. The aim of the present narrative review was to highlight sex- and gender-related discrepancies in primary and secondary CVD prevention, underscoring plausible underlying mechanisms. Manifestation of CVD in women is characterized by atypical symptoms/signs and inadequately studied pathophysiology features challenging accurate diagnosis and effective treatment. Regarding CVD risk assessment, the burden and effect size of conventional, novel, and female-specific risk factors needs better clarification. Hitherto outcomes are nonconsistent, while most importantly, the interpretation of the attendant metabolic paths remains a challenge; the interactions among genetic, metabolic, and environmental factors are of high complexity regulated by genomic and nongenomic sex hormones effects. To deal with these key points, the National Institutes of Health currently calls upon investigators to provide a sex- and gender-specific reporting in all health research hypotheses. The implementation of high-quality studies addressing these issues is an imperative need to maximize cost-effectiveness in prevention and management strategies.

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.

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.

The chemerin production changes in obese patients with different carbohydrate metabolism state

Chemerin is a mediator of adipose tissue involved in the regulation of many processes, including lipogenesis, and inflammatory response. The role of chemerin in the development of insulin resistance has been insufficiently studied and needs detailed understanding. The aim of the study was to investigate chemerin production in obese patients with different states of carbohydrate metabolism. The study included 155 patients with a diagnosis of obesity; 34 patients with overweight. The control group 1 consisted of 43 conditionally healthy donors who did not have obesity. For comparison of the results of a study to determine the levels of tissue-specific mRNA expression of the genes IL-6, TNF-a, RARRES2, (encoding IL-6, TNF-a and chemerin) in adipose tissue introduced a control group 2 – 30 patients without obesity. Study on the relative level of mRNA expression of the genes IL-6, TNF-a and RARRES2 (encoding IL-6, TNF-a and chemerin) was carried out using real time PCR. Concentrations of IL-6, TNF-a, and chemerin were measured in serum/plasma using an enzyme-linked immunosorbent assay (ELISA). We found significant differences in the plasma level of chemerin and tissue-specific features of RARRES2 gene expression in obese patients, depending on the degree of obesity and the state of carbohydrate metabolism. Multidirectional associations of RARRES2 gene expression with TNF-a and IL-6 genes in adipose tissues of different localization are shown: in obese patients (BMI £40 kg/m2) without type 2 diabetes – negative, and type 2 diabetes – positive. Identified relationship chemerin plasma content and the expression level of its gene in biopsies with various parameters of carbohydrate and lipid metabolism, proinflammatory molecules indicate chemerin involved in metabolic and immune processes in obesity.

CMKLR1 activation ex vivo does not increase proportionally to serum total chemerin in obese humans

Prochemerin is the inactive precursor of the adipokine chemerin. Proteolytic processing is obligatory for the conversion of prochemerin into active chemerin and subsequent regulation of cellular processes via the chemokine-like receptor 1 (CMKLR1). Elevated plasma or serum chemerin concentrations and differential processing of prochemerin have been reported in obese humans. The impact of these changes on CMKLR1 signalling in humans is unknown. The objective of this pilot study was to develop a cellular bioassay to measure CMKLR1 activation by chemerin present in human serum and to characterise how obesity modifies serum activation of CMKLR1 under fasted and fed conditions. Blood samples were collected from control (N = 4, BMI 20-25) and obese (N = 4, BMI >30) female subjects after an overnight fast (n = 2) and at regular intervals (n = 7) following consumption of breakfast over a period of 6 h. A cellular CMKLR1-luminescent reporter assay and a pan-chemerin ELISA were used to determine CMKLR1 activation and total chemerin concentrations, respectively. Serum total chemerin concentration (averaged across all samples) was higher in obese vs control subjects (17.9 ± 1.8 vs 10.9 ± 0.5 nM, P < 0.05), but serum activation of CMKLR1 was similar in both groups. The CMKLR1 activation/total chemerin ratio was lower in obese vs control subjects (0.33 ± 0.04 vs 0.58 ± 0.05, P < 0.05). After breakfast, serum total chemerin or CMKLR1 activation did not differ from baseline values. In conclusion, the unexpected observation that obese serum activation of CMKLR1 did not match increased total chemerin concentrations suggests impaired processing to and/or enhanced degradation of active chemerin in serum of obese humans.

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.

Serum Chemerin Levels Are Associated with Abdominal Visceral Fat in Type 2 Diabetes

Chemerin is a recently identified adipokine suggested to play a role in obesity and its metabolic complications. The relationship between visceral obesity and serum chemerin levels in type 2 diabetes (T2DM) is unknown and may differ from that of subjects without diabetes. Therefore, we evaluated whether serum chemerin was associated with visceral abdominal obesity in patients with T2DM. A total of 218 Korean patients with T2DM were enrolled and metabolic parameters, abdominal visceral and subcutaneous fat areas, and serum chemerin levels were measured. Serum chemerin level showed positive correlation with fasting insulin, HOMA-IR, serum triglyceride, serum creatinine, urine albumin/creatinine ratio, high-sensitivity C-reactive protein (hsCRP), fibrinogen, abdominal visceral fat area, visceral to subcutaneous fat area ratio, and negatively correlation with high density lipoprotein cholesterol and creatinine clearance (CCr) after adjusting for age, gender and body mass index. Multiple linear stepwise regression analysis showed that abdominal visceral fat area (β = 0.001, P < 0.001), serum triglyceride (β = 0.001, P < 0.001), CCr (β = -0.003, P = 0.001), hsCRP (β = 0.157, P = 0.001), fibrinogen (β = 0.001, P < 0.001) and BMI (β = 0.02, P = 0.008) independently affected log transformed serum chemerin levels. Higher serum chemerin level was associated with higher level of abdominal visceral fat area, serum triglyceride, hsCRP and fibrinogen and lower level of CCr in patients with T2DM. Serum chemerin may be used as a biomarker of visceral adiposity and chemerin may play a role in inflammation, decreased renal function, and increased cardiovascular risk in T2DM.

Pro-inflammatory chemokines CCL2, chemerin, IP-10 and RANTES in human serum during an oral lipid tolerance test

BACKGROUND

There is a strong coincidence of obesity and a chronic state of modest inflammation. Secretion of pro-inflammatory cytokines from adipocytes and immune cells represents a key mechanism in this process and is affected by fatty acids.

MATERIAL AND METHODS

A study cohort of 100 overnight fasted healthy volunteers underwent an oral lipid tolerance test (OLTT) by ingestion of 160ml of a protein- and sugar-free lipid emulsion of defined composition. Venal blood was drawn at 0h (fasting) and at 2, 4, and 6h after lipid ingestion. Subjects were characterized by anthropometric and standard laboratory parameters. Serum concentrations of CCL2, IP-10, chemerin, and RANTES were measured by enzyme-linked immunosorbent assay (ELISA). Murine 3T3-L1 adipocytes were stimulated with free fatty acids (FA) and with sex steroids and concentrations of CCL2 and chemerin in cell culture supernatants were measured by ELISA.

RESULTS

A significant reduction of circulating CCL2, IP-10, and chemerin concentrations was observed as a consequence of triglyceride ingestion whereas RANTES levels were increased. CCL2 serum concentrations were positively correlated with resistin and visfatin levels and with LDL/HDL ratio and negatively with adiponectin. There were significant differences in chemerin and RANTES serum concentrations in female and male subjects. CCL2 secretion from 3T3-L1 adipocytes was inhibited by treatment with linoleic (LA) and oleic acid (OA) whereas chemerin secretion was induced. Chemerin release from 3T3-L1 adipocytes was inhibited by testosterone.

CONCLUSIONS

Oral lipid loading is linked to reduced circulating pro-inflammatory chemokines CCL2, IP-10, and chemerin and to increased RANTES levels, suggesting that dietary lipids affect immune function.

Independent Association of Circulating Level of Chemerin With Functional and Early Morphological Vascular Changes in Newly Diagnosed Type 2 Diabetic Patients

There is growing evidence that chemerin, a novel adipokine elevated in obesity and metabolic syndromes, plays a crucial role in advanced atherosclerosis. This study aimed to determine the chemerin levels in diabetes and evaluate the effects of increased chemerin on early atherosclerosis.A total of 245 newly diagnosed diabetic patients and 148 age-matched, healthy, normal glucose tolerant (NGT) controls were enrolled. Anthropometric measurements and plasma parameters were examined, including body mass index (BMI), waist circumference, blood pressure, glucose, lipid profiles, inflammation markers, adipokines, and cell adhesion molecules. Vascular healthy was measured with brachial flow-mediated dilatation (FMD) and carotid intima-media thickness (IMT).Compared with NGT controls, plasma chemerin levels were higher in diabetic patients (P < 0.01) and higher chemerin level was an independent risk factor of occurrence of diabetes even after metabolic profiles were adjusted (odds ratio [OR] = 1.352, 95% CI: 1.181-1.543, P < 0.01). In patients with type 2 diabetes, chemerin was positively associated with intercellular adhesion molecule-1 (ICAM-1), E-selectin, but not vascular adhesion molecule-1 (VCAM-1) and P-selectin. We also explored that plasma chemerin level was negatively associated with brachial FMD and positively with carotid IMT. Chemerin also retained a strong association with ICAM-1, FMD, and IMT even after adjusted for age, sex, and other risk factors (ICAM-1: r = 0.150, P = 0.024; FMD: r = -0.126, P = 0.001; IMT: r = 0.325, P < 0.001). By multiple linear regression analysis, plasma chemerin levels were related to ICAM-1 even after adjustments for conventional cardiovascular risk factors (β = 0.192, P = 0.017). Moreover, logistic regression analysis showed that high chemerin level was an independent predictive variable for impaired endothelial function (OR = 1.066, 95% CI: 1.012-1.142, P = 0.048) and enhanced carotid vessel thickness (OR = 1.068, 95% CI: 1.021-1.148, P = 0.035) in diabetic patients.In summary, chemerin levels are independently associated with endothelial activation and early atherosclerosis in newly diagnosed type 2 diabetes.

Chemerin and prediction of Diabetes mellitus type 2

OBJECTIVE

Insulin resistance and subclinical inflammation are characteristics in the development of type 2 diabetes mellitus (T2DM). The adipokine chemerin has been associated with both factors. The aim of this study was to analyse whether chemerin predicts T2DM.

DESIGN

Blood samples of 440 participants of the Metabolic-Syndrome Berlin-Potsdam (MesyBepo) follow-up study without diabetes at baseline were available for chemerin measurement. Mean follow-up of participants was 5·3 years. Glucose metabolism was analysed using oral glucose tolerance test including insulin measurements. Chemerin was measured using a commercially available ELISA.

RESULTS

Thirty-five individuals developed T2DM during follow-up. Chemerin predicted incident T2DM (Chemerin 1. Tertile: reference, 2. Tertile: OR 2·33 [0·68-7·95]; Chemerin 3. Tertile: OR 3·42 [1·01-11·58] after adjustment for age, sex, BMI, follow-up time, HbA1c, HOMA-IR and WHR). In a secondary analysis, chemerin also predicted worsening of fasting glucose and HbA1c (adjusted for age, sex, BMI, time of follow-up, WHR, HDL cholesterol and triglycerides).

CONCLUSIONS

Our data suggest that chemerin is a weak predictor of T2DM.

Serum Chemerin Concentrations Associate with Beta-Cell Function, but Not with Insulin Resistance in Individuals with Non-Alcoholic Fatty Liver Disease (NAFLD)

The novel adipokine chemerin has been related to insulin-resistant states such as obesity and non alcoholic fatty liver disease (NAFLD). However, its association with insulin resistance and beta cell function remains controversial. The main objective was to examine whether serum chemerin levels associate with insulin sensitivity and beta cell function independently of body mass index (BMI), by studying consecutive outpatients of the hepatology clinics of a European university hospital. Individuals (n=196) with NAFLD were stratified into persons with normal glucose tolerance (NGT; n=110), impaired glucose tolerance (IGT; n=51) and type 2 diabetes (T2D; n=35) and the association between serum chemerin and measures of insulin sensitivity and beta cell function as assessed during fasting and during oral glucose tolerance test (OGTT) was measured. Our results showed that serum chemerin positively associated with BMI (P=0.0007) and C peptide during OGTT (P<0.004), but not with circulating glucose, insulin, lipids or liver enzymes (all P>0.18). No BMI independent relationships of chemerin with fasting and OGTT derived measures of insulin sensitivity were found (P>0.5). Chemerin associated positively with fasting beta cell function as well as the OGTT derived insulinogenic index IGI_cp and the adaptation index after adjustment for age, sex and BMI (P=0.002-0.007), and inversely with the insulin/C peptide ratio (P=0.007). Serum chemerin neither related to the insulinogenic index IGI_ins nor the disposition index. In conclusion, circulating chemerin is likely linked to enhanced beta cell function but not to insulin sensitivity in patients with NAFLD.

Association between serum chemerin concentrations and clinical indices in obesity or metabolic syndrome: a meta-analysis

OBJECTIVE

Chemerin is a novel adipokine. Previous research has investigated the association between chemerin and clinical indices in patients with obesity or metabolic syndrome (MS), although the results obtained have been inconsistent. We conducted a meta-analysis to investigate the association between chemerin and clinical indicators of diabetes, MS and obesity with obesity or MS subjects.

DESIGN AND METHODS

Studies were identified by searching the PubMed, the Cochrane Library, EMBASE and CNKI, databases beginning with the original report in July 2007 until the end of May 2013. For each variable, summary correlation coefficients were estimated using random-effects or fixed-effect meta-analysis with 95% confidence interval (CI) performed by STATA software.

RESULTS

A total of eight studies with 20 clinical variables (total n = 1787) met the inclusion criteria. The meta-analyse of diabetes markers showed that FSI (rs = 0.26; 95% CI = 0.21-0.31; P = 0.000), 2HPG (rs = 0.06; 95% CI = 0.01-0.12; P = 0.030) and HOMA-IR (rs = 0.178; 95% CI = 0.019-0.337; P = 0.028) were positively correlated with chemerin, however, FPG (rs = 0.03, 95% CI = -0.02 to 0.08, P = 0.240) and HbA1c (rs = -0.05; 95% CI = -0.24-0.15; P = 0.641) were not significantly correlated with chemerin. The meta-analyses of MS and obesity markers indicated that TG, TC, CRP BMI, TBF%, WC, WHR and Leptin were positively correlated with chemerin, nevertheless, SBP, DBP, LDL-C, HDL-C, ALT and r-GT were not significantly correlated, adiponectin was negatively correlated. Sensitivity analysis was performed and the summary results did not change significantly.

CONCLUSIONS

The results suggest that chemerin in patients with obesity or MS may be associated with obesity, imbalances in lipid and diabetes metabolism and insulin resistance. Chemerin played an important role in the pathophysiology of obesity and MS.

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.