Serum Chemerin Levels Correlate With Determinants of Metabolic Syndrome in Obese Children and Adolescents

Chemerin regulates glucose and lipid metabolism by changing mitochondrial structure and function associated with androgen/androgen receptor

The adipokine chemerin contributes to exercise-induced improvements in glucose and lipid metabolism; however, the underlying mechanism remains unclear. We aimed to confirm the impact of reduced chemerin expression on exercise-induced improvement in glycolipid metabolism in male diabetic (DM) mice through exogenous chemerin administration. Furthermore, the underlying mechanism of chemerin involved in changes in muscle mitochondria function mediated by androgen/androgen receptor (AR) was explored by generating adipose-specific and global chemerin knockout (adipo-chemerin-/- and chemerin-/-) mice. DM mice were categorized into the DM, exercised DM (EDM), and EDM + chemerin supplementation groups. Adipo-chemerin-/- and chemerin-/- mice were classified in the sedentary or exercised groups and fed either a normal or high-fat diet. Exercise mice underwent a 6-wk aerobic exercise regimen. The serum testosterone and chemerin levels, glycolipid metabolism indices, mitochondrial function, and protein levels involved in mitochondrial biogenesis and dynamics were measured. Notably, exogenous chemerin reversed exercise-induced improvements in glycolipid metabolism, AR protein levels, mitochondrial biogenesis, and mitochondrial fusion in DM mice. Moreover, adipose-specific chemerin knockout improved glycolipid metabolism, enhanced exercise-induced increases in testosterone and AR levels in exercised mice, and alleviated the detrimental effects of a high-fat diet on mitochondrial morphology, biogenesis, and dynamics. Finally, similar improvements in glucose metabolism (but not lipid metabolism), mitochondrial function, and mitochondrial dynamics were observed in chemerin-/- mice. In conclusion, decreased chemerin levels affect exercise-induced improvements in glycolipid metabolism in male mice by increasing mitochondrial number and function, likely through changes in androgen/AR signaling.NEW & NOTEWORTHY Decreased chemerin levels affect exercise-induced improvements in glycolipid metabolism in male mice by increasing mitochondrial number and function, which is likely mediated by androgen/androgen receptor expression. This study is the first to report the regulatory mechanism of chemerin in muscle mitochondria.

Mechanisms and risk factors of metabolic syndrome in children and adolescents

Metabolic syndrome (MetS) is a complex disorder characterized by abdominal obesity, elevated blood pressure, hyperlipidemia, and elevated fasting blood glucose levels. The diagnostic criteria for MetS in adults are well-established, but there is currently no consensus on the definition in children and adolescents. The etiology of MetS is believed to involve a complex interplay between genetic predisposition and environmental factors. While genetic predisposition explains only a small part of MetS pathogenesis, modifiable environmental risk factors play a significant role. Factors such as maternal weight during pregnancy, children's lifestyle, sedentariness, high-fat diet, fructose and branched-chain amino acid consumption, vitamin D deficiency, and sleep disturbances contribute to the development of MetS. Early identification and treatment of MetS in children and adolescents is crucial to prevent the development of chronic diseases later in life. In this review we discuss the latest research on factors contributing to the pathogenesis of MetS in children, focusing on non-modifiable and modifiable risk factors, including genetics, dysbiosis and chronic low-grade inflammation.

Not Only Metabolic Complications of Childhood Obesity

The increasing incidence of obesity in the pediatric population requires attention to its serious complications. It turns out that in addition to typical, well-known metabolic complications, obesity as a systemic disease carries the risk of equally serious, although less obvious, non-metabolic complications, such as cardiovascular diseases, polycystic ovary syndrome, chronic kidney disease, asthma, thyroid dysfunction, immunologic and dermatologic conditions, and mental health problems. They can affect almost all systems of the young body and also leave their mark in adulthood. In addition, obesity also contributes to the exacerbation of existing childhood diseases. As a result, children suffering from obesity may have a reduced quality of life, both physically and mentally, and their life expectancy may be shortened. It also turns out that, in the case of obese pregnant girls, the complications of obesity may also affect their unborn children. Therefore, it is extremely important to take all necessary actions to prevent the growing epidemic of obesity in the pediatric population, as well as to treat existing complications of obesity and detect them at an early stage. In summary, physicians treating a child with a systemic disease such as obesity must adopt a holistic approach to treatment.

Amino acid profile in overweight and obese prepubertal children - can simple biochemical tests help in the early prevention of associated comorbidities?

Background

It is accepted that plasma branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs) are closely related to metabolic risk. Arterial hypertension, metabolic syndrome, endothelial dysfunction, inflammation, and metabolic dysfunction-associated fatty liver disease (MAFLD) are frequently seen in obese patients. Many attempts have been made to find biochemical indicators for the early detection of metabolic complications in children. It is not known if different amino acid profiles and BCAA and AA concentrations in overweight and obese children correlate with chemerin, proinflammatory, and simple biochemical markers. Thus, the study aimed to find out the early markers of cardiovascular disease and MAFLD in overweight and obese children.

Materials and methods

The study included 20 overweight and obese children (M/F 12/8; mean age 7.7 ± 2.3 years; BMI 26.8 ± 5.0 kg/m2) and 12 non-obese children (control group) (M/F 4/8; mean age 6.5 ± 2.2 years; BMI 14.8 ± 1.5 kg/m2). The following plasma amino acids were measured: aspartic acid, glutamic acid, serine, asparagine, glycine, glutamine, taurine, histidine, citrulline, threonine, alanine, arginine, proline, tyrosine, methionine, valine, isoleucine, leucine, phenylalanine, tryptophan, ornithine, and lysine. Chemerin, high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), and basic biochemistry parameters were measured.

Results

The mean plasma levels of leucine, isoleucine, valine, phenylalanine, tyrosine, glutamic acid, and alanine were significantly higher in overweight and obese children than in the control group (p<0.03-p<0.0004). Conversely, the mean values of serine, asparagine, glutamine, and citrulline were significantly lower in overweight and obese children than in the control group (p<0.03-p<0.0007). Isoleucine, leucine, valine (BCAAs) tyrosine, and phenylalanine (AAAs) levels showed a positive correlation with uric acid, ALT, hs-CRP, and chemerin (r=0.80-0.36; p<0.05-p<0.00001), but not with IL-6. The mean values of glucose, IL-6, hs-CRP, chemerin, uric acid, and ALT were significantly higher in overweight and obese children than in the control group (p<0.03-p<0.00002). In contrast, the lipid profile did not differ between groups.

Conclusion

An abnormal amino acid profile in overweight and obese pre-pubertal children, accompanied by elevated ALT and UA observed in the studied cohort, may suggest early metabolic disturbances that can potentially lead to metabolic syndrome, or MAFLD, and increased cardiovascular risk.

Adipokines as Clinically Relevant Therapeutic Targets in Obesity

Adipokines provide an outstanding role in the comprehensive etiology of obesity and may link adipose tissue dysfunction to further metabolic and cardiovascular complications. Although several adipokines have been identified in terms of their physiological roles, many regulatory circuits remain unclear and translation from experimental studies to clinical applications has yet to occur. Nevertheless, due to their complex metabolic properties, adipokines offer immense potential for their use both as obesity-associated biomarkers and as relevant treatment strategies for overweight, obesity and metabolic comorbidities. To provide an overview of the current clinical use of adipokines, this review summarizes clinical studies investigating the potential of various adipokines with respect to diagnostic and therapeutic treatment strategies for obesity and linked metabolic disorders. Furthermore, an overview of adipokines, for which a potential for clinical use has been demonstrated in experimental studies to date, will be presented. In particular, promising data revealed that fibroblast growth factor (FGF)-19, FGF-21 and leptin offer great potential for future clinical application in the treatment of obesity and related comorbidities. Based on data from animal studies or other clinical applications in addition to obesity, adipokines including adiponectin, vaspin, resistin, chemerin, visfatin, bone morphogenetic protein 7 (BMP-7) and tumor necrosis factor alpha (TNF-α) provide potential for human clinical application.

The link between vitamin D, chemerin and metabolic profile in overweight and obese children - preliminary results

Background

Vitamin D affects adipogenesis, oxidative stress, inflammation, secretion of adipocytokines, lipid metabolism and thermogenesis. Some researchers postulate that those effects could be exerted by the influence of vitamin D on chemerin levels.

Aim of the study

We aimed to investigate if there is a link between serum 25-hydroksyvitamin D [25(OH)D], chemerin and metabolic profile in overweight and obese children before and after vitamin D supplementation.

Material and methods

The prospective study included 65 overweight and obese children aged 9.08-17.5 years and 26 peers as a control. None of the patients in the study group had received vitamin D within the last twelve months before the study.

Results

The study group had lower baseline 25(OH)D (p<0.001) and higher chemerin (p<0.001), triglycerides (TG, p<0.001), triglycerides/high density lipoprotein cholesterol (TG/HDL-C, p<0.001), C-reactive protein (CRP, p<0.05), fasting insulin (p<0.001), Homeostasis Model Assessment - Insulin Resistance (HOMA-IR, p<0.001), alanine aminotransferase (ALT, p<0.001) and uric acid (p<0.001) compared to the control group. Baseline vitamin D was related to fasting insulin (R=-0.29, p=0.021), HOMA-IR (R=-0.30, p=0.016), HDL-C (R=0.29, p=0.020) and uric acid (R=-0.28, p=0.037) in the study group. Baseline chemerin was related to insulin at 30' (R=0.27, p=0.030), 60' (R=0.27, p=0.033), 90' (R=0.26, p=0.037) and 120' (R=0.26, p=0.040) during the oral glucose tolerance test (OGTT) and ALT (R=0.25, p=0.041) in the study group. Correlation between vitamin D and chemerin (R=-0.39, p=0.046) was found only in the control group. After six months of vitamin D supplementation a decrease in CRP (p<0.01), total cholesterol (p<0.05), ALT (p<0.01), glucose at 150' OGTT (p<0.05) was observed. Moreover, we noticed a tendency for negative association between 25(OH)D and chemerin levels (p=0.085). Multivariable backward linear regression models were build using baseline vitamin D, baseline chemerin and six months chemerin as the dependent variables.

Conclusions

Our study confirmed that vitamin D has positive effect on metabolic profile in overweight and obese children. The relationship between vitamin D and chemerin is not clear, nevertheless we have observed a tendency to decrease chemerin concentrations after improving vitamin D status, even without a significant reduction in body fat mass.

Assessment of serum chemerin levels in acanthosis nigricans: A case-control study

BACKGROUND

Acanthosis nigricans (AN) is an asymptomatic skin condition linked to several underlying systemic conditions. Chemerin is an adipokine that increases during inflammatory disorders such as metabolic syndrome (MetS).

AIMS

This case-control study investigates the link between AN and the underlying MetS and serum levels of chemerin in individuals with obesity.

PATIENTS/METHODS

Twenty-five adults with AN and obesity (body mass index [BMI] > 30 kg/m² ), 25 adults with obesity but no AN, and 25 healthy controls (BMI < 30 kg/m² ) had their lipid profiles and serum chemerin concentrations examined.

RESULTS

The neck (80.0%) and axilla (68.0%) were the most common sites of AN. In participants with obesity, either alone or with AN, serum chemerin concentrations were significantly higher than in the control group (p < 0.001). Participants with obesity and AN had significantly higher levels of cholesterol, triglycerides (TG), low-density lipoprotein cholesterol (LDL-c), and serum chemerin levels (p < 0.001), and significantly lower high-density lipoprotein cholesterol (HDL-c) levels (p < 0.001) when compared to participants with obesity alone. All participants with obesity and AN (100%) and 88% of those with obesity alone had MetS. Logistic regression revealed that systolic blood pressure >130 mmHg, diastolic blood pressure >85 mmHg, waist circumference >90 cm, TG >150 mg/dl, HDL-c <45 mg/dl, fasting blood glucose >100 mg/dl, and serum chemerin >300 ng/ml were significant (p < 0.05) risk factors for AN.

CONCLUSIONS

Acanthosis nigricans is a non-invasive and reliable sign of the underlying MetS and increased serum chemerin levels among individuals with obesity.

The relevance of left ventricular functions to clinical and metabolic characteristics of prepubertal children with obesity

BACKGROUND

Paediatric obesity is a worldwide health burden, with growing evidence linking obesity to myocardial function impairments. The study aims to evaluate left ventricular functions among prepubertal obese children to obesity-related clinical and metabolic parameters.

METHODS

Between June 2019 and March 2020, 40 prepubertal children with obesity were recruited and compared to 40 healthy controls. Patients were assessed for body mass index z scores, waist circumference, body adiposity by bioimpedance analysis, and obesity-related laboratory tests, for example, serum chemerin. Left ventricular functions were assessed using variable echocardiographic modalities, such as M-mode, tissue Doppler, and two-dimensional speckle tracking.

RESULTS

Mean patients' age was 9.25 ± 1.05 years. Left ventricular mass index, E/E', and myocardial performance index were significantly increased in obese children than controls. Although M-mode-derived ejection fraction was comparable in both groups, two-dimensional speckle tracking-derived ejection fraction, global longitudinal strain, and global circumferential strain were significantly lower in cases than controls. Left ventricular mass index displayed a positive correlation with body mass index z score (p = 0.003), fat mass index (p = 0.037), and trunk fat mass (p = 0.021). Global longitudinal strain was negatively correlated with body mass index z score (p = 0.015) and fat mass index (p = 0.016). Serum chemerin was positively correlated with myocardial performance index (p = 0.01).

CONCLUSION

Alterations of left ventricular myocardial functions in prepubertal obese children could be detected using different echocardiographic modalities. Chemerin, body mass index z score, fat mass index, and trunk fat mass were correlated with subclinical left ventricular myocardial dysfunction parameters before puberty. Our results reinforce early and strict management of childhood obesity upon detection of changes in anthropometric and body adiposity indices.

Role of Chemerin/ChemR23 axis as an emerging therapeutic perspective on obesity-related vascular dysfunction

Sufficient epidemiological investigations demonstrate that there is a close correlation between obesity and vascular dysfunction. Nevertheless, specific mechanisms underlying this link remain currently unclear. Given the crucial and decisive role of vascular dysfunction in multitudinous diseases, various hypotheses had been proposed and numerous experiments were being carried out. One recognized view is that increased adipokine secretion following the expanded mass of white adipose tissue due to obesity contributes to the regulation of vascular function. Chemerin, as a neo-adipokine, whose systemic level is elevated in obesity, is believed as a regulator of adipogenesis, inflammation, and vascular dysfunction via binding its cell surface receptor, chemR23. Hence, this review aims to focus on the up-to-date proof on chemerin/chemR23 axis-relevant signaling pathways, emphasize the multifarious impacts of chemerin/chemR23 axis on vascular function regulation, raise certain unsettled questions to inspire further investigations, and explore the therapeutic possibilities targeting chemerin/chemR23.

Chemerin as Potential Biomarker in Pediatric Diseases: A PRISMA-Compliant Study

Adipose tissue is the main source of adipokines and therefore serves not only as a storage organ, but also has an endocrine effect. Chemerin, produced mainly in adipocytes and liver, is a natural ligand for chemokine-like receptor 1 (CMKLR1), G-protein-coupled receptor 1 (GPR1) and C-C motif chemokine receptor-like 2 (CCRL2), which have been identified in many tissues and organs. The role of this protein is an active area of research, and recent analyses suggest that chemerin contributes to angiogenesis, adipogenesis, glucose homeostasis and energy metabolism. Many studies confirm that this molecule is associated with obesity in both children and adults. We conducted a systematic review of data from published studies evaluating chemerin in children with various disease entities. We searched PubMed to identify eligible studies published prior to February 2022. A total of 36 studies were selected for analysis after a detailed investigation, which was intended to leave only the research studies. Moreover, chemerin seems to play an important role in the development of cardiovascular and digestive diseases. The purpose of this review was to describe the latest advances in knowledge of the role of chemerin in the pathogenesis of various diseases from studies in pediatric patients. The mechanisms underlying the function of chemerin in various diseases in children are still being investigated, and growing evidence suggests that this adipokine may be a potential prognostic biomarker for a wide range of diseases.

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.

Promotion of chemerin in rat diabetic kidney disease through enhancement of TGF-β1/Smads/CTGF pathway

OBJECTIVE

Although increasing evidence shows that the adipokine chemerin is involved in diabetic kidney disease (DKD), it is still unclear whether the chemerin acts as a critical element in renal function through the signaling pathways of transforming growth factor β1/Smads/connective tissue growth factor (TGF-β1/Smads/CTGF) in the context of DKD. Therefore, we sought to determine the role of chemerin and TGF-β1/Smads/CTGF signaling pathway in the development and/or progression of DKD.

METHODS

We used rat renal mesangial cells (RMCs) and a DKD rat model as study subjects. RMCs and rats were randomly separated into different groups and transfected with the constructed chemerin expression vector pcDNA™ 3.1 (+)-chemerin. Rat renal function and inflammatory cytokines were assessed after treatment with chemerin or CCX832 (ChemR23 antagonist). Real time polymerase chain reverse transcription (RT-QPCR) was used to detect the mRNA expressions of TGF-β1, Smad2, Smad4, and CTGF. Western blot was performed to determine protein expression for semiquantitative analysis.

RESULTS

In in vitro studies, the mRNA and protein levels of TGF-β1, Smad2, Smad4, and CTGF were significantly increased in the groups of high glucose and chemerin as compared to the normal control and normal glucose groups, most notably in the high glucose chemerin group (all P<0.05). In vivo studies revealed that the mRNA and protein levels of TGF-β1, Smad2, Smad4, and CTGF were higher in the DKD group and the normal chemerin group than in the normal control group and the blocking receptor group, while appearing the highest in the DKD chemerin group (all P<0.05). Moreover, kidney/body weight ratio, urea, creatinine, and urine protein were increased, and the weight and endogenous creatinine clearance rate decreased in the DKD group and the normal chemerin group (all P<0.05). These changes were more pronounced in the DKD chemerin group. At the same time, blood glucose, triglycerides (TGs), and total cholesterol (TC) in the blocked receptor group was lower than those in the DKD group and the DKD chemerin group (all P<0.05). In contrast to those in the normal control group and blocked receptor group, tumor necrosis factor alpha (TNF-α) and interleukin (IL)-1 showed higher concentrations in the DKD group and the normal chemerin group. This result was more pronounced in the DKD chemerin group (all P<0.05).

CONCLUSION

Chemerin may play a role in DKD by enhancing the signaling pathways of TGF-β1/Smads/CTGF transduction either in vitro or in vivo. Moreover, high glucose accelerates kidney injury by activating fibrotic pathways.

Expression of adipokines in children with primary nephrotic syndrome and its association with hyperlipidemia

OBJECTIVES

To study the expression of adipokines in children with primary nephrotic syndrome (PNS) before and after treatment and its correlation with blood lipids, as well as the role of adipokines in PNS children with hyperlipidemia.

METHODS

A total of 90 children who were diagnosed with incipient PNS or recurrence of PNS after corticosteroid withdrawal for more than 6 months were enrolled as subjects. Thirty children who underwent physical examination were enrolled as the control group. Venous blood samples were collected from the children in the control group and the children with PNS before corticosteroid therapy (active stage) and after urinary protein clearance following 4 weeks of corticosteroid therapy (remission stage). ELISA was used to measure the levels of adipokines. An automatic biochemical analyzer was used to measure blood lipid levels.

RESULTS

Compared with the control group, the children with PNS had a significantly lower level of omentin-1 in both active and remission stages, and their level of omentin-1 in the active stage was significantly lower than that in the remission stage (P<0.001). For the children with PNS, the level of chemerin in the active stage was significantly higher than that in the remission stage, and the children with PNS in the active stage had a significantly higher level of chemerin than the control group (P<0.001). For the children with PNS, atherogenic index of plasma, atherogenic coefficient (AC), castelli risk index-1 (CRI-1), castelli risk index-2 (CRI-2), and non-high-density lipoprotein in the active stage were significantly higher than those in the remission stage (P<0.001), and these indices in the children with PNS in the active stage were significantly higher than those in the control group (P<0.001). The children with PNS in the remission stage had significantly higher atherogenic index of plasma, AC, CRI-1, and non-high-density lipoprotein than the control group (P<0.001). Compared with the control group, the children with PNS in the remission stage had significantly higher serum levels of total cholesterol, triglyceride, high-density lipoprotein, low-density lipoprotein, apolipoprotein B, and apolipoprotein A (P<0.01). In the children with PNS, the ratio of omentin-1 before and after corticosteroid therapy was positively correlated with that of high-density lipoprotein, 24-hour urinary protein excretion, and high-density lipoprotein/apolipoprotein A before and after treatment, and it was negatively correlated with the ratio of AC and CRI-1 before and after treatment (P<0.05). The PNS children with low omentin-1 levels in the active stage had significantly higher levels of CRI-1, CRI-2, AC, and apolipoprotein B/apolipoprotein A ratio than those with high omentin-1 levels (P<0.05).

CONCLUSIONS

Omentin-1 may be associated with disease activity, dyslipidemia, and proteinuria in children with PNS. Blood lipid ratios may be more effective than traditional blood lipid parameters in monitoring early cardiovascular risk in children with PNS.

Adipo-specific chemerin knockout alters the metabolomic profile of adipose tissue under normal and high-fat diet conditions: Application of an untargeted liquid chromatography-tandem mass spectrometry metabolomics method

To explore the metabolic effect of chemerin, adipose-specific chemerin knockout (adipo-chemerin^-/- ) male mice were established and fed with 5-week normal diet (ND) or high-fat diet (HFD), and then the glycolipid metabolism index was measured and epididymal adipose tissue metabolomics detected using untargeted LC-tandem mass spectrometry (LC-MS/MS). Under HFD, adipo-chemerin^-/- mice showed improved glycolipid metabolism (decreased total cholesterol, low-density lipoprotein-cholesterol, insulin and Homeostasis Model Assessment of Insulin Resistance) compared with flox (control) mice. Furthermore, orthogonal partial least squares-discriminant analysis score plots identified separation of metabolites between adipo-chemerin^-/- mice and flox mice fed ND and HFD. Under HFD, 28 metabolites were significantly enhanced in adipo-chemerin^-/- mice, and pathway enrichment analysis suggested strong relationship of the differential metabolites with arginine and proline metabolism, phenylalanine metabolism, and phenylalanine, tyrosine and tryptophan biosynthesis, which were directly or indirectly related to lipid metabolism, inflammation and oxidative stress. Under ND, taurine was increased in adipo-chemerin^-/- mice, resulting in taurine and hypotaurine metabolism and primary bile acid biosynthesis. In conclusion, the improved effect of chemerin knockdown on the glycolipid metabolism of HFD-feeding male mice might be associated with the increases in differential metabolites and metabolic pathways involved in lipid metabolism, inflammation and oxidative stress, which provided insights into the mechanism of chemerin from a metabolomics aspect.

Association between Toxoplasma gondii infection and metabolic syndrome in obese adolescents: A possible immune-metabolic link

Background Toxoplasmosis as a global disease is considered as a triggering factor responsible for development of several clinical diseases. However, Toxoplasma gondii (T. gondii) is an understudied parasite of potential interest in obesity research. The current study aimed to explore the role of latent T. gondii infection in the pathogenesis of metabolic syndrome (MetS) in obese adolescents through studying the relationship between serum interferon-gamma [IFN-γ] and serum chemerin in context of MetS components. Methods Eighty-three obese adolescents were serologically screened for T. gondii-IgG antibodies and compared to 35 age-matched healthy T. gondii-seronegative controls. Participants were evaluated for anthropometric measurements, total-fat mass [FM], trunk-FM, serum lipid profile, IFN-γ, and chemerin levels. Homeostatic Model Assessment of insulin resistance (HOMA-IR) was calculated. Results The prevalence of MetS was significantly higher within obese T. gondii-seropositive group compared to obese T. gondii-seronegative group (P = 0.033). Seropositive obese MetS group displayed significantly higher trunk-FM, HOMA-IR, chemerin, and IFN-γ compared to seronegative obese MetS group. Serum chemerin and IFN-γ were strongly correlated (P < 0.001) and were positively correlated with BMI, WC, total-FM, trunk-FM, HOMA-IR, cholesterol, triglycerides and negatively correlated with HDLC. HOMA-IR was a common predictor for serum chemerin (P = 0.030) and IFN-γ (P < 0.001). Conclusions The study results suggest that T. gondii infection may exert an immune-metabolic effect that may have a potential role in the development of MetS among obese adolescents.

The role of chemerin in the pathogenesis of cholelithiasis in children and adolescents

BACKGROUND AND AIM

Adipokines and hepatokines are proteins secreted by adipose tissue and the liver. To date, the levels of adipokines and hepatokines in cholelithiasis have only been evaluated in studies in adult patients. The purpose of our research was to assess the levels of circulating adipokines: chemerin, vaspin, progranulin, retinol-binding protein 4 (RBP-4) and hepatokine: fibroblast growth factor 21 (FGF-21) and to compare their concentrations in paediatric patients with and without cholelithiasis.

METHODS

The prospective study included 54 children and adolescents diagnosed with gallstones and 26 controls. Fasting serum levels of adipokines and hepatokine were determined by enzyme-linked immunosorbent assays.

RESULTS

The serum levels of chemerin, FGF-21 and RBP-4 were significantly higher in children and adolescents with gallstones compared to the control group. Elevated levels of triglycerides, RBP-4, and a homeostatic model for assessing insulin resistance (HOMA-IR) were observed in overweight or obese patients compared to patients with normal weight and cholelithiasis. Chemerin concentrations were increased in the normal-weight children and adolescents with cholelithiasis compared to the control group. Children and adolescents with gallstones and abnormal weight had significantly higher levels of chemerin, FGF-21 and RBP-4 than healthy controls.

CONCLUSION

Elevated serum chemerin levels were significantly higher in non-obese patients with cholelithiasis than in non-obese controls, suggesting a potential role of chemerin in the development of cholelithiasis in children and adolescents.

Higher Lipopolysaccharide Binding Protein and Chemerin Concentrations Were Associated with Metabolic Syndrome Features in Pediatric Subjects with Abdominal Obesity during a Lifestyle Intervention

Background: Elevated circulating plasma levels of both lipopolysaccharide-binding protein (LBP) and chemerin are reported in patients with obesity, but few studies are available on lifestyle intervention programs. We investigated the association of both LBP and chemerin plasma levels with metabolic syndrome (MetS) outcomes in a lifestyle intervention in children and adolescents with abdominal obesity Methods: Twenty-nine patients enrolled in a randomized controlled trial were selected. The lifestyle intervention with a 2-month intensive phase and a subsequent 10-month follow-up consisted of a moderate calorie-restricted diet, recommendations to increase physical activity levels, and nutritional education. Results: Weight loss was accompanied by a significant reduction in MetS prevalence (−43%; p = 0.009). Chemerin (p = 0.029) and LBP (p = 0.033) plasma levels were significantly reduced at 2 months and 12 months, respectively. At the end of intervention, MetS components were associated with both LBP (p = 0.017) and chemerin (p < 0.001) plasma levels. Conclusions: We describe for the first time a reduction in both LBP and chemerin plasma levels and its association with MetS risk factors after a lifestyle intervention program in children and adolescents with abdominal obesity. Therefore, LBP and chemerin plasma levels could be used as biomarkers for the progression of cardiovascular risk in pediatric populations.

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.

Serum Calprotectin and Chemerin Concentrations as Markers of Low-Grade Inflammation in Prepubertal Children with Obesity

In adults, obesity is associated with chronic low-grade inflammation, which may cause long-term adverse health consequences. We evaluated whether obesity in prepubertal children also generates this kind of inflammation and whether calprotectin and chemerin may be useful markers for early detection of such inflammation in this group of children. The study population included 83 children aged 2 to 10 years; 62 with obesity and without components of metabolic syndrome and 21 healthy controls with normal body weight. White blood cell (WBC) count, concentrations of C-reactive protein (CRP), interleukin-6 (IL-6), calprotectin, and chemerin were determined in peripheral blood. Our study showed that in the group with obesity, serum concentrations of calprotectin and chemerin, as well as CRP were significantly higher as compared with the controls. We found a significant positive correlation between serum chemerin concentrations and BMI z-score (r = 0.33, p < 0.01) in children with obesity. Chemerin concentration was also positively correlated with CRP level (r = 0.36, p < 0.01) in the whole group of children. These findings suggest that obesity may generate chronic low-grade inflammation as early as in the prepubertal period which can be indicated by significantly higher serum concentrations of calprotectin and chemerin. Calprotectin and especially chemerin seem to be promising indicators of this type of inflammation in children with obesity, but the correlation between these markers requires further research.

Circulating chemerin level and risk of cancer: a systematic review and meta-analysis

Aim: Circulating chemerin level has been reported to be higher in patients with various types of cancer. However, the conclusions obtained are not unified. The aim of present study is to draw an evidence-based conclusion on the relationship between circulating chemerin and risk of cancer. Materials & methods: A systematic search was carried out in PubMed and Web of Science up to 30 June 2019. The random-effects model was applied to calculate summary standardized mean differences with 95% CIs. Results: The meta-analysis included a total of 12 separate studies, 876 cases and 739 healthy controls. The results showed that the expression level of circulating chemerin was significantly higher in cancer patients than that in control group (pooled standardized mean difference = 1.47, 95% CI = 1.03–1.90). Conclusion: This meta-analysis concludes that a high level of circulating chemerin is strongly associated with cancer risk.

Chemerin concentrations in infants born small for gestational age: correlations with triglycerides and parameters related to glucose homeostasis

Infants born small for gestational age (SGA) are known to have increased risk of developing several pathologies, including the metabolic syndrome, when they grow up. It has been described that both the growth pattern of these children as well as the risk of their presenting future metabolic disorders can be influenced by the expression of adipokines. Among them, chemerin has demonstrated to be implicated in lipid and glucose metabolism, presenting higher circulating concentration in diabetic and obese subjects. Thus, the aim of this study was to analyze the association of anthropometric parameters and plasmatic biochemical parameters with circulating chemerin concentration in SGA children. This prospective, longitudinal study was carried out in plasma samples of Caucasian children born SGA at Hospital Universitario de Álava-Txagorritxu. Significant positive correlations were observed between chemerin concentrations at 3 months and insulin values at 3 months and also with triglyceride levels at 24 months. These associations were maintained after adjustment by anthropometric parameters. Therefore, we suggest that circulating chemerin concentration, measured at an early age, might be an indicator of future metabolic alterations in SGA 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 in immune response and gastrointestinal pathophysiology

Chemerin is a multifunctional protein involved among others in adipogenesis, angiogenesis and lipid as well as glucose metabolism. Chemerin is an essential factor in promotion of chemotaxis of numerous immune cell types and plays an important role in several pathophysiologic conditions. Chemerin receptors are present on monocytes/macrophages, T cells, natural killer and dendritic cells as well as neutrophils. However, the role of chemerin and chemerin receptors in immune response and gastrointestinal diseases is still poorly understood. Accumulating, clinical and experimental studies observed disturbation of chemerin and chemerin receptors in a number of disorders including Barrett's esophagus, esophageal cancer, gastric cancer, hepatic dysfunction, irritable bowel syndrome, inflammatory bowel disease and colorectal cancer. Moreover, chemerin and chemerin receptors have been shown to regulate proliferation, migration and invasion of gastrointestinal and immune cells as well as cancer-associated fibroblasts. In this review we present the current state of knowledge about the contribution of chemerin to immune response and gastrointestinal disorders.