Circulating irisin, omentin-1, and lipoprotein subparticles in adults at higher cardiovascular risk

The association of serum irisin with anthropometric, metabolic, and bone parameters in obese children and adolescents

Background

Irisin is an adipomyokine secreted by muscle and adipose cells, and it plays a role in glucose, fat, and bone metabolism. This study aimed to determine the correlation of serum irisin levels with anthropometric, metabolic, and bone parameters in obese children and adolescents.

Methods

This single-center study included 103 Korean children and adolescents: 54 (52.4%) obese participants with a body mass index (BMI) ≥95th percentile and 49 (47.6%) healthy controls with BMI within the 15th to 85th percentile. Various parameters were measured, including fasting blood glucose, fasting insulin, homeostasis model assessment of insulin resistance (HOMA-IR), triglyceride and glucose (TyG) index, lipid profile, alkaline phosphatase (ALP), osteocalcin, and 25(OH)-Vitamin D levels. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DEXA) in 33 healthy subjects.

Results

Serum irisin was significantly higher in the obese group than in the control group (mean 18.1 ± 3.5 vs. 16.2 ± 2.0 ng/mL; p = 0.001). Serum irisin level was positively correlated with chronological age (r = 0.28; p = 0.004), height SDS (r = 0.24; p = 0.02), BMI SDS (r = 0.37; p < 0. 001), fasting glucose (r = 0.27; p = 0.007), fasting insulin (r = 0.23; p = 0.03), HOMA-IR (r = 0.21; p = 0.04), osteocalcin (r = 0.27; p = 0.006) and negatively correlated with HDL cholesterol (r = -0.29; p = 0.005). All these correlations were evident in obese subjects but not in healthy subjects. ALP and 25(OH)-Vitamin D were unrelated to irisin levels. Among 33 healthy subjects, total body-less head (TBLH) BMD Z-score was positively correlated with serum irisin (r = 0.39; p = 0.03), osteocalcin (r = 0.40; p = 0.02), fasting insulin (r = 0.39; p = 0.04), and HOMA-IR (r = 0.38; p = 0.047).

Conclusion

This study demonstrated an association between irisin levels and glucose, lipid, and bone parameters in children and adolescents. Our findings suggest that irisin has a potential role in metabolic disorders and bone health in obese children and adolescents.

Irisin and Cardiometabolic Disorders in Obesity: A Systematic Review

Background

Overweight and obesity are global health issues, impacting a significant portion of young adults. Obesity is a complex condition influenced by genetics and environmental factors, leading to increased susceptibility to cardiovascular diseases (CVDs), hypertension, dyslipidemia, and insulin resistance. Irisin, a protein derived from the cleavage of fibronectin type III domain-containing protein 5, may have relationship with these cardiometabolic diseases.

Objective

This systematic review aims to examine the relationship between serum irisin levels and obesity, particularly in individuals predisposed to cardiovascular risk factors.

Methods

A thorough literature search was conducted in multiple databases, including "Science Direct," "Scopus," "PubMed," and "Lilacs," from July 2020. Inclusion criteria encompassed subjects with metabolic disorders (with or without obesity, BMI ≥30 kg/m2), clinical trials, and observational studies published between 2010 and June 2020. Exclusion criteria were animal studies, meta-analyses, systematic reviews, studies evaluating only healthy subjects, and those investigating disorders beyond cardiometabolic diseases.

Results

Out of 151 identified articles, 30 met the inclusion criteria. These studies, published between 2013 and 2020, assessed adults (≥21 years) and included 26 observational studies and 4 clinical trials (n = 7585 subjects). All studies examined irisin's role in obesity and CVDs, often including associated diseases such as type 2 diabetes and hypertension. Despite varying sample sizes, the samples within the articles were homogeneous. Observational studies exhibited a low risk of bias in at least 60% of the evaluated domains. Clinical trials demonstrated a low risk of bias in at least 50% of the domains. Limitations. Although the systematic review provides valuable insights, it is limited by the available literature and the varying methodologies used across studies.

Conclusion

The review suggests that irisin plays a significant role as both a preventive measure and a biomarker for comorbidities linked to obesity and cardiometabolic disorders. Future research should focus on standardized irisin measurement methods and diverse populations to further elucidate its mechanisms of action.

Adipokines in atherosclerosis: unraveling complex roles

Adipokines are biologically active factors secreted by adipose tissue that act on local and distant tissues through autocrine, paracrine, and endocrine mechanisms. However, adipokines are believed to be involved in an increased risk of atherosclerosis. Classical adipokines include leptin, adiponectin, and ceramide, while newly identified adipokines include visceral adipose tissue-derived serpin, omentin, and asprosin. New evidence suggests that adipokines can play an essential role in atherosclerosis progression and regression. Here, we summarize the complex roles of various adipokines in atherosclerosis lesions. Representative protective adipokines include adiponectin and neuregulin 4; deteriorating adipokines include leptin, resistin, thrombospondin-1, and C1q/tumor necrosis factor-related protein 5; and adipokines with dual protective and deteriorating effects include C1q/tumor necrosis factor-related protein 1 and C1q/tumor necrosis factor-related protein 3; and adipose tissue-derived bioactive materials include sphingosine-1-phosphate, ceramide, and adipose tissue-derived exosomes. However, the role of a newly discovered adipokine, asprosin, in atherosclerosis remains unclear. This article reviews progress in the research on the effects of adipokines in atherosclerosis and how they may be regulated to halt its progression.

The Role of Omentin-1 in Cancers Development and Progression

Adipose tissue serves as an energy store and is also an active endocrine organ, exerting activity that influences obesity-related processes through the production of regulatory proteins called adipokines or adipocytokines. Adipokines play important direct and indirect roles in the pathogenesis of insulin resistance, the regulation of local and systemic inflammatory processes, and related metabolic complications. There have been an increasing number of studies showing the relationship between some adipokines and carcinogenesis. This work reviews the current literature concerning the effects of omentin-1 on carcinogenesis.

Association between irisin and metabolic parameters in nondiabetic, nonobese adults: a meta-analysis

BACKGROUND

Irisin has been proposed to have a beneficial influence on the metabolic status of animals and humans. However, the relationship between circulating irisin levels and the risks of metabolic components in humans remains unclear. In the present meta-analysis, we aimed to evaluate the association between circulating irisin and metabolic parameters in nonobese, nondiabetic adults.

METHODS

We searched PubMed, Embase, the Cochrane Library, Web of Science and ClinicalTrial.gov using the main search terms and identified original articles published prior to March 7, 2022. Studies that met our inclusion criteria and reported the association between irisin and metabolic parameters were included in our meta-analysis. We used the Newcastle Ottawa scale to assess the quality of the included studies.

RESULTS

A total of 14 studies (711 subjects) in 11 articles were included for qualitative and quantitative synthesis. The pooled results showed that circulating irisin was positively and significantly correlated with fasting blood glucose (r = 0.159), HOMA-IR (r = 0.217) and waist-to-hip ratio (WHR) (r = 0.168). However, no significant association was detected between irisin levels and other metabolic parameters.

CONCLUSIONS

Thus, these findings indicated the possible link between irisin levels and part of the metabolic parameters in apparently metabolically normal individuals. However, the regulation of irisin in metabolism in humans remains to be fully elucidated, and well-designed prospective studies will be needed in the future. Trial registration The review protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO): CRD42022315269.

Irisin Is Related to Non-Alcoholic Fatty Liver Disease (NAFLD)

Irisin is a cytokine involved in many metabolic pathways occurring, among others, in muscles, adipose tissue and liver. Thus, fluctuations in irisin levels are suggested to be related to metabolic diseases. Therefore, the purpose of our study was to evaluate whether irisin may be associated with non-alcoholic fatty liver disease (NAFLD). A total of 138 patients (70/68 male/female, mean age 65.61 ± 10.44 years) were enrolled in the study. The patients were assigned to the NAFLD group (n = 72, including 46 patients with type 2 diabetes (T2DM]) and the group without NAFLD (n = 66, 31 patients with T2DM). NAFLD was diagnosed based on ultrasound examination, Hepatic Steatosis Index (HSI) and Fatty Liver Index. Baseline anthropometric, blood pressure and biochemical parameters were collected. The serum irisin level was determined using an ELISA test. We observed that NAFLD was associated with an increased concentration of irisin. Moreover, Spearman correlations and linear regression analysis revealed that irisin level correlates with some anthropometric and biochemical parameters such as body mass index, glycated hemoglobin, aspartic aminotransferase, creatinine and urea. Logistic regression analysis depicted that odds for NAFLD increase 1.17 times for each 1 μg/mL rise of irisin concentration. Finally, ROC analysis showed that the concentration of irisin possesses a discriminate capacity for NAFLD and optimal cut points concentration could be designed. The risk of NAFLD in the subgroup with irisin concentration above 3.235 μg/mL was 4.57 times higher than in patients with the lower concentration of irisin. To conclude, the obtained results suggest that irisin concentration is associated with some anthropometric and biochemical parameters and should be further investigated toward its usage as a diagnostic biomarker of NAFLD.

The modulatory effects of irisin on asprosin, leptin, glucose levels and lipid profile in healthy and obese male and female rats

OBJECTIVES

The main aim of this study was to investigate the effects of irisin on asprosin, leptin, glucose levels and lipid profile in healthy and obese male and female rats.

METHODS

Irisin was subcutaneously administered with osmotic minipumps at the dose of 100 ng/kg/day for 28 days and then, the serum levels of asprosin, leptin, glucose and lipid profile were investigated.

RESULTS

Irisin infusion increased asprosin levels in male rats (p = .02) but not in female rats. Irisin inhibited obesity-induced high glucose, low-density lipoprotein (LDL), triglyceride (TG) and leptin levels in all groups; however, it did not lead to any change in asprosin levels in both obese female and male rats.

CONCLUSIONS

It was determined that irisin increased serum asprosin levels and decreased LDL, TG, glucose and leptin levels, and this could indicate a protective role of irisin against obesity development.

NEW BIOMARKERS TO PREDICT CARDIOVASCULAR RISK IN PATIENTS WITH ADRENAL INCIDENTALOMA; IRISIN AND NESFATIN-1

OBJECTIVE

In our study, we aimed to investigate the levels of irisin, nesfatin-1 and the relationship between levels of these relatively new molecules with cardiometabolic risk markers; carotid intima-media thickness (CIMT), epicardial adipose tissue (EAT) thickness in patients with nonfunctional adrenal incidentaloma (NFAI).

MATERIALS AND METHODS

Patients with NFAI (n=59) and age, sex and body mass index-matched healthy control subjects (n=59) were enrolled in this study. Serum glucose, insulin, C-reactive protein (CRP), lipid, irisin and nesfatin-1 levels and echocardiographic CIMT and EAT thickness measurements were performed in patients and controls.

RESULTS

The irisin level was 17.58 ± 4.38 pg/mL in the NFAI group, significantly higher (p<0.001) than 14.03 ± 4.03 pg/mL in the control group. Nesfatin-1 level was significantly lower in the NFAI group 194.98 ± 119.15 pg/mL ((p < 0.001)) versus 303.48 ± 200.78 pg/mL in the control group. A positive correlation was found between irisin and nesfatin-1 levels and CIMT and EAT thickness in the NFAI group.

CONCLUSIONS

In our study, we found that irisin level was higher and nesfatin-1 level was lower in patients with NFAI, and both irisin and nesfatin-1 levels were associated with CIMT and EAT thickness in NFAI patients.

Omentin-1: A newly discovered warrior against metabolic related diseases

INTRODUCTION

: Chronic metabolism-related diseases are challenging clinical problems. Omentin-1 is mainly expressed in stromal vascular cells of adipose tissue and can also be expressed in airway goblet cells, mesothelial cells, and vascular cells. Omentin-1 has been found to exert important anti-inflammatory, antioxidative and anti-apoptotic roles and to regulate endothelial dysfunction. Moreover, omentin-1 also has protective effects against cancer, atherosclerosis, type 2 diabetes mellitus, and bone metabolic diseases. The current review will discuss the therapeutic potential of omentin-1.

AREAS COVERED

: This review summarizes the biological actions of omentin-1 and provides an overview of omentin-1 in metabolic-related diseases. The relevant literature was derived from a PubMed search spanning 1998-2021 using these search terms: omentin-1, atherosclerosis, diabetes mellitus, bone, cancer, inflammation, and oxidative stress.

EXPERT OPINION

: As a novel adipocytokine, omentin-1 is a promising therapeutic target in metabolic-related diseases. Preclinical animal studies have shown encouraging results. Moreover, circulating omentin-1 has excellent potential as a noninvasive biomarker. In the future, strategies for regulating omentin-1 need to be investigated further in clinical trials in a large cohort.

INFLUENCE OF GLYCEMIC CONTROL AND BODY COMPOSITION ON IRISIN LEVELS IN CHILDREN WITH TYPE 1 DIABETES MELLITUS

AIM

We investigated the relationship between irisin concentrations and glycemic control, body composition and anthropometric measures in children with type 1 diabetes mellitus.

METHODS

The study involved 40 subjects with T1DM prospectively. Glycemic control was evaluated. Body composition was analyzed with a bioimpedance analyzer (BIA). Serum irisin concentrations were measured using an ELISA kit.

RESULTS

Irisin levels were found higher in BMI <17 kg/m² group (p=0.002) compared to BMI >17 kg/m². Irisin level was negatively correlated with weight, height, BMI, fat free mass, skeletelal muscle mass, basal metabolic rate (r= -0.40, p= 0.011; r=-0.32, p=0.046; r=-0.366, p= 0.022; r=-0.423, p= 0.007; r=-0.430, p=0.006; r=-0.416, p=0.009, respectively); there was a strong correlation between LDL-C and irisin levels (r=0.367, p=0.02). In multivariate linear regression analyses model, irisin concentrations were correlated with weight (ß-coefficient= - 0.391, p= 0.015). LDL-C is associated, but not correlated significantly with irisin levels, (ß-coefficient =0.272, p=0.084).

CONCLUSION

As a result, weight and LDL-C were the predictors of circulating irisin. To our knowledge, this study is the first examining association between irisin levels and body composition comprehensively, in children with type 1 diabetes mellitus.

Omentin-1: a biomarker in large artery ischaemic stroke patients

Background

Omentin-1 is a novel adipocytokine that is related to atherosclerosis-based ischaemic cardiovascular disease and stroke. Previous studies have linked its lower levels with poor stroke outcomes. We aimed to assess the level of serum omentin-1 as a prognostic marker in patients with large artery ischaemic stroke.

Methods

Fifty ischaemic stroke patients suffering large artery ischaemic stroke and another 50 subjects without a prior history of strokes were recruited. All participants were subjected to neurological examinations, echocardiography and laboratory investigations including a lipid profile and HBA1c. Carotid intima-media thickness (IMT) was measured for all participants. Stroke patients were evaluated by the National Institute of Health Stroke Scale (NIHSS) and the modified Rankin Scale (mRS). Infarction volume was measured by magnetic resonance image (MRI) and serum level of omentin-1 was gauged for all participants.

Results

Carotid IMT significantly increased in stroke patients compared to control subjects. While serum omentin-1 levels were higher in control non-diabetic subjects, they were lower in diabetic patients with ischaemic stroke. Serum omentin-1 levels were inversely correlated with NIHSS, carotid IMT, infarction volume and mRS scores in all stroke patients. Serum omentin-1 level less than 24.5 ng/ml showed 93.7%sensitivity and 44.4% specificity in prediction of poor stroke outcome while values less than 27.8 ng/ml in non-diabetic stroke patients had sensitivity and specificity with 87.5% and 55.6% respectively.

Conclusion

Lower levels of serum omentin-1 are associated with increased ischaemic stroke severity and poor functional outcome.

The Emerging Role of Irisin in Cardiovascular Diseases

Irisin, a novel hormone like polypeptide, is cleaved and secreted by an unknown protease from a membrane‐spanning protein, FNDC5 (fibronectin type III domain‐containing protein 5). The current knowledge on the biological functions of irisin includes browning white adipose tissue, regulating insulin use, and anti‐inflammatory and antioxidative properties. Dysfunction of irisin has shown to be involved in cardiovascular diseases such as hypertension, coronary artery disease, myocardial infarction, and myocardial ischemia–reperfusion injury. Moreover, irisin gene variants are also associated with cardiovascular diseases. In this review, we discuss the current knowledge on irisin‐mediated regulatory mechanisms and their roles in the pathogenesis of cardiovascular diseases.

Fibronectin type III domain-containing 5 in cardiovascular and metabolic diseases: a promising biomarker and therapeutic target

Cardiovascular and metabolic diseases are the leading causes of death and disability worldwide and impose a tremendous socioeconomic burden on individuals as well as the healthcare system. Fibronectin type III domain-containing 5 (FNDC5) is a widely distributed transmembrane glycoprotein that can be proteolytically cleaved and secreted as irisin to regulate glycolipid metabolism and cardiovascular homeostasis. In this review, we present the current knowledge on the predictive and therapeutic role of FNDC5 in a variety of cardiovascular and metabolic diseases, such as hypertension, atherosclerosis, ischemic heart disease, arrhythmia, metabolic cardiomyopathy, cardiac remodeling, heart failure, diabetes mellitus, and obesity.

Irisin and Vascular Inflammation: Beneficial Effects of a Healthy Lifestyle Beyond Physical Activity

Vascular inflammation is responsible for many cardiovascular diseases and endothelial dysfunction is often the first trigger. Many factors can contribute to altering vascular homeostasis and despite that some risk factors cannot be changed, some lifestyle changes might dramatically improve vascular function. In this regard, physical activity has been identified as one of the most important interventions that can positively affect endothelial dysfunction. In recent years, the discovery of irisin, a novel myokine with pleiotropic effects, has caught the attention of many researchers. This review summarizes the most relevant intervention trials, evaluating irisin modifications in subjects with or without cardiovascular risk factors assigned to physical activity programs, to improve cardiovascular risk markers.

Thyroid hormones modulate irisin concentrations in patients with recently onset hypothyroidism following total thyroidectomy

PURPOSE

Irisin is a newly discovered adipo-myokine known for having significant effects on body metabolism. Currently, there is a discussion regarding the relation between thyroid function and irisin concentration. This study was designed to evaluate the influential role of levothyroxine replacement therapy on circulating levels of irisin in patients with recently onset hypothyroidism following total thyroidectomy.

METHODS

Circulating levels of thyroid hormones, irisin and other metabolic parameters, were assessed in 40 recently thyroidectomized patients (34 females, mean age 50.1 ± 15.2 years) at baseline (5-7 day after surgery) and after 2 months under replacement therapy with levothyroxine.

RESULTS

At baseline, circulating levels of thyroid hormones were indicative of hypothyroidism (TSH 12.7 ± 5.0 μU/mL, FT3 1.9 ± 0.7 pg/mL, FT4 8.7 ± 3.6 pg/mL). Mean serum irisin concentrations significantly increased after 2 months under replacement therapy with levothyroxine (from 2.2 ± 0.6 to 2.9 ± 0.6 μg/mL, p < 0.0001). Variations of circulating levels of irisin under levothyroxine replacement therapy were directly correlated with those of FT3 (Rho = 0.454, p = 0.0033) and FT4 (Rho = 0.451, p = 0.0035). Multivariate regression analysis revealed that changes in thyroid hormones concentrations explained up to 10% of the variations of serum irisin levels under levothyroxine replacement therapy (FT3 R² = 0.098, FT4 R² = 0.103).

CONCLUSION

Our study suggests that levothyroxine replacement therapy mildly influences irisin metabolism in patients with recently onset hypothyroidism following total thyroidectomy.

Omentin-1: Protective impact on ischemic stroke via ameliorating atherosclerosis

Omentin-1, a newly identified adipokine, has recently been revealed as a novel biomarker for ischemic stroke (IS). Low circulating omentin-1 levels could indicate a high risk of IS, and elevated omentin-1 levels exert a favorable impact on cerebral ischemia. Furthermore, omentin-1 has anti-atherosclerotic, anti-inflammatory, and cardiovascular protective capabilities through the intracellular Akt/AMP-activated protein kinase (AMPK)/ nuclear factor-κB (NF-κB) and certain protein kinase (ERK, JNK, and p38) signaling pathways. Omentin-1 also alleviates endothelial cell dysfunction, improves revascularization via the Akt-endothelial nitric-oxide synthase (eNOS) regulatory axis, promotes endothelium-dependent vasodilation through endothelium-derived NO in an eNOS fashion, and inhibits VSMC proliferation by means of AMPK/ERK signaling pathways, VSMC migration via inactivation of the NADPH oxidase (NOX)/ROS/p38/HSP27 pathways and artery calcification via the PI3K-Akt pathway. These findings indicate that omentin-1 may be a negative mediator of IS. Pharmacologically, several lines of clinical evidence indicate that metformin and statins could elevate omentin-1 levels, although the specific mechanism has not been precisely delineated until now. This study is the first to summarize the comprehensive mechanisms between omentin-1 and atherosclerosis and to review the shielding effect of omentin-1 on IS. We shed light on omentin-1 as a novel therapeutic target for combating IS.

Irisin: A New Code Uncover the Relationship of Skeletal Muscle and Cardiovascular Health During Exercise

Exercise not only produces beneficial effects on muscle itself via various molecular pathways, but also mediates the interaction between muscles and other organs in an autocrine/paracrine manner through myokines, which plays a positive role in maintaining overall health. Irisin, an exercise-derived myokine, has been found involved in the regulation of some cardiovascular diseases. However, the relationship between irisin and cardiovascular health is not fully elucidated and there are some divergences on the regulation of irisin by exercise. In this review, we present the current knowledge on the origin and physiology of irisin, describe the regulation of irisin by acute and chronic exercises, and discuss the divergences of the related research results. Importantly, we discuss the role of irisin as a biomarker in the diagnosis of cardiovascular diseases and describe its treatment and molecular mechanism in some cardiovascular diseases. It is expected that irisin will be used as a therapeutic agent to combat cardiovascular diseases or other disorders caused by inactivity in the near future.

Serum Levels of Irisin and Omentin-1 in Breast Neoplasms and Their Association with Tumor Histology

Breast cancer is associated with obesity, possibly due to direct effects of adipokines and myokines, such as omentin-1 and irisin. In this study, we aimed to evaluate omentin-1 and irisin levels in women with benign and/or malignant breast neoplasms vs. healthy controls. Disease-free individuals (N = 56) and patients with histologically proven benign (N = 61) or malignant tumor (N = 96; subdivided into recently diagnosed/treatment-naïve (N = 72) and chemotherapy-treated (N = 24) subgroups) were enrolled in this study. Demographic, biochemical, and tumor histological characteristics were recorded. Body composition parameters were assessed using bioelectrical impedance. Serum irisin and omentin-1 levels were quantified with ELISA kits. In adjusted models, irisin levels were higher in both benign and malignant cases compared to controls but were comparable between neoplasms. Further adjustment for omentin-1 levels showed that age (odds ratio (OR) = 1.05, 95% confidence interval (95% CI) = (1.02, 1.08), p < 0.01) and irisin levels (OR = 5.30, 95% CI = (1.24, 22.38), p=0.03) were independent predictors of the presence of malignancy. These molecules were associated with each other and with other anthropometric and demographic parameters. Irisin was associated with tumor histological characteristics including Ki67% levels, Elston-Ellis grading system, and estrogen receptors status. Omentin-1 was also associated with the Elston-Ellis grading system. In conclusion, serum irisin is increased in patients with both benign and malignant diseases of the breast. When combined with omentin-1, irisin concentration was associated with the presence of breast malignancy. This molecule's role as a potential diagnostic and/or prognostic agent in breast malignancies warrants further investigation in larger prospective studies.

A pilot study on the relation between irisin single-nucleotide polymorphism and risk of myocardial infarction

BACKGROUND

Myocardial infarction (MI) is the major cause of death and disability worldwide. Many recent studies revealed the relationship between circulating irisin levels, endothelial dysfunctions and subclinical atherosclerosis in adult patients.

OBJECTIVES

The aim of this study was to investigate the distribution of Irisin gene single nucleotide polymorphism in patients with MI and its association with other clinical and laboratory variables in these patients.

PATIENTS AND METHODS

This study was carried out in 100 patients with MI, and 100 healthy subjects served as controls. All studied subjects underwent laboratory investigations, including measurement of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-c) high-density lipoprotein cholesterol (HDL-c), creatinine kinase-MB (CK-MB), troponin I (TnI) and genotyping of rs 3480 and rs726344 of Irisin genes using the TaqMan Allelic Discrimination assay technique.

RESULTS

There was a significant difference of Irisin genotypes in patients when compared to controls. By estimating odd ratio (OR) an association was found between G allele of rs 3480 and A allele of rs726344with increase the risk of developing myocardial infarction by 4.03 and 3.47 fold respectively. GG of rs 3480 carriers had significantly increased Troponin I and triglyceride levels, while GA carriers of rs726344 had significantly increased CKMB, Total cholesterol, LDLc, HDLc, troponin I and triglyceride levels compared with other genotypes.

CONCLUSION

G allele of rs 3480 and A allele of rs726344can considered as genetic risk factors for MI; these findings could have an impact on preventive strategy for myocardial infarction.

Association of serum omentin concentration with anthropometric, physiological, and biochemical parameters in obese individuals

OBJECTIVE

Omentin is a secretory protein produced in visceral adipose tissue. The potential protective action of omentin in metabolic disorders is not yet fully understood. The aim of this study was to determine the association of omentin with anthropometric, physiologic, and biochemical parameters in obese individuals.

METHODS

Sixty obese individuals and 40 normal weight controls were enrolled in the study. Anthropometric measurements were taken, systolic (SBP) and diastolic blood pressures (DBP) were recorded. Serum fasting glucose, insulin, homeostatic model assessment of insulin resistance (HOMA-IR), lipid profile, and serum omentin concentrations were determined.

RESULTS

The concentration of omentin in obese individuals was significantly lower than in controls (145.5 ± 33.3 versus 383.6 ± 92.9; P < 0.001). Omentin correlated negatively with waist circumference (P < 0.01), hip circumference (P < 0.05), percent of adipose tissue (P < 0.001), fasting insulin (P < 0.001), HOMA-IR (P < 0.001), and SBP (P < 0.001) in the patients who were obese. A positive relationship was documented with high-density lipoprotein in both the obese patients (P < 0.01) and the overall population (P < 0.001). Multiple negative omentin correlations with body weight, body mass index, waist and hip circumference and its ratio, percent of adipose tissue, SBP, triacylglycerols, glucose, fasting insulin, and HOMA-IR were demonstrated in the entire population. In the multivariate linear regression model, insulin concentration (β = -0.49; P < 0.001), percent of adipose tissue (β = -0.31; P < 0.001), and waist circumference (β = -0.21; P < 0.01) were independent predictors of omentin concentration in individuals who were obese.

CONCLUSIONS

A concentration of omentin is associated with cardiometabolic risk-related factors in obesity. Fasting insulin, adipose tissue percentage, and waist circumference can be considered candidates for markers of omentin concentration in obese individuals.

Serum omentin-1 and risk of one-year mortality in patients with ischemic stroke

BACKGROUND

Prior studies suggested that ischemic stroke patients with high omentin-1 concentrations were at a decreased risk of unstable carotid plaque and 3-month poor functional outcome. We aim to evaluate the association between serum omentin-1 and 1-y mortality after ischemic stroke.

METHODS

A total of 303 ischemic stroke patients were prospectively followed up at 1 y. Outcome was defined as death occurred during the follow-up period. A multivariable Cox model was used to evaluate the association between serum omentin-1 concentrations and 1-y mortality among ischemic stroke patients.

RESULTS

From lowest to highest tertile of serum omentin-1, the 1-y cumulative death rate was 12%, 3.7% and 2.1%, respectively (P = 0.006). The hazard ratio (95% confidence interval) of the highest tertile compared with the lowest tertile was 0.19 (0.04-0.88) for mortality after multivariable adjustment (P for trend < 0.01). The net reclassification index and integrated discrimination improvement were significantly improved in predicting 1-y mortality when omentin-1 data was added to the multivariable Cox regression model.

CONCLUSIONS

Among patients with ischemic stroke, high baseline serum omentin-1 was associated with a decreased risk of 1-y mortality. These findings, if confirmed by clinical trials, suggest that increasing omentin-1 concentrations may lower the risk of mortality among ischemic stroke patients.

Association of polymorphisms of preptin, irisin and adropin genes with susceptibility to coronary artery disease and hypertension

OBJECTIVES

Preptin, irisin and adropin are 3 new players in energy regulation that are related body mass index, lipids, glucose and insulin levels which may affect incidence of cardiovascular diseases. The aim of the present study was to evaluate eight single nucleotide polymorphisms (SNPs) of preptin genes (rs1003483, rs1004446, rs2239681, rs680, and rs3741204), irisin (rs16835198 and rs3480) and adropin (rs2281997) gene in patients with coronary artery disease (CAD) and hypertension.

METHODS

This case-control study was carried out on 372 volunteers, which were divided into 3 subgroups including: CAD patients with hypertension (CAD+H+), CAD patients with no hypertension (CAD+H-), and non-hypertensive non-CAD subjects as control group (CAD-H-) as health control. Genomic DNA from whole blood was extracted and eight SNPs were assessed using polymerase chain reaction- ligase detection reaction method.

RESULTS

A significant difference was found in the genotype and allele frequency of preptin rs1003483 gene in CAD+H+ compared to CAD+H- groups (P = .019 and P = .018, respectively). Allele frequency of rs1003483 was significantly different between CAD+H- groups and healthy control groups (P = .043). There also existed a significant difference the genotype frequency of rs1004446 gene in CAD+H+ compared to CAD+H- groups (P = .027).

CONCLUSIONS

The findings of present study revealed that the preptin rs1003483 and rs1004446 gene polymorphism might serve as predisposing factor in CAD and hypertension.

Irisin as a mediator between obesity and vascular inflammation in Chinese children and adolescents

BACKGROUND AND AIM

This study aims to characterize the role of Irisin in obesity and early onset metabolic and vascular sequelae in Chinese children. Furthermore, we aim to examine whether Irisin mediate endothelial cells dysfunction and vascular inflammation which eventually leads to obesity.

METHODS AND RESULTS

We quantified plasma Irisin levels using enzyme-linked immunosorbent assay (ELISA) among 85 lean and 120 obese children, and assessed the association of Irisin levels with anthropometric, metabolic, cardiovascular and inflammatory parameters of obese children comparing with lean children. We further characterized the markers for endothelial cells and inflammation between obese and lean children to assess potential correlations. In addition, a potential direct effect of Irisin on the expression of endothelial adhesion molecules was assessed in human coronary artery endothelial cells. Irisin levels from obese children was significantly lower than lean children, and this reduced Irisin levels is correlated with certain physical parameters of studied children. Moreover, we identified significant inverse associations between inflammation markers of endothelial activation with Irisin levels in obese children. Multiple regression analyses confirm Irisin serves as a strong predictor of SDS-SBP, Ang-2, ICAM-1, E-selectin and hsCRP levels, independent of SDS-BMI. Lifestyle intervention results in a significant improvement of these cardiovascular and inflammatory parameters, and these were accompanied by a significant improvement of Irisin levels and weight loss. Finally, in the mediation effect model, our data showed that Irisin changes act as partial mediators of the relationship between SDS-BMI changes and changes in inflammatory and endothelial parameters for ICAM-1, E-selectin and hsCRP after controlling for covariates. Likewise, on the cellular level, Irisin inhibition hsCPR, ICAM-1 and E-selectin expression in endothelial cells, whereas Ang-2, VCAM-1 and eNOS expression were unaffected.

CONCLUSIONS

Our study showed that Irisin levels change may indicate the early stages of cardiovascular disease in obese children.

Impact of serum omentin-1 concentrations on functional outcome among acute intracerebral hemorrhage patients

BACKGROUND

Reduced serum omentin-1 concentrations might be related to an increased risk for poor functional outcome after acute ischemic stroke. We intended to explore whether serum omentin-1 could be a promising prognostic biomarker for acute intracerebral hemorrhage.

METHODS

A total of 104 consecutive patients with hemorrhagic stroke underwent 90-day follow-up. The modified Rankin scale score >2 was evaluated as worse prognosis. A multivariable logistic model was conFig.d for assessing the relationship between serum omentin-1 concentrations and functional outcome.

RESULTS

Serum omentin-1 concentrations, with the median value of 147.9 ng/ml (interquartile range, 114.7-199.8 ng/ml), were substantially declined with rising modified Rankin scale scores (P < 0.001). Serum omentin-1 concentrations <147.9 ng/ml was independently related to higher risk of 90-day worse prognosis (odds ratio, 3.789; 95% confidence interval, 1.819-8.608; P = 0.018). Under receiver operating characteristic curve, an optimal value of serum omentin-1 concentrations was selected as 179.7 ng/ml, which yielded 0.88 sensitivity value and 0.70 specificity value for discriminating patients at risk of 90-day worse prognosis (area under curve, 0.82; 95% confidence interval, 0.73-0.89).

CONCLUSIONS

Lower serum omentin-1 concentrations are closely associated with poor functional outcome after hemorrhagic stroke, substantializing serum omentin-1 as a potential prognostic biomarker for acute intracerebral hemorrhage.

Associations of Preoperative Irisin Levels of Paired Cerebrospinal Fluid and Plasma with Physical Dysfunction and Muscle Wasting Severity in Residents of Surgery Wards

BACKGROUND

Myokine Irisin has been proposed to regulate metabolic homeostasis, which is related to chronic diseases or physical activity. However, whether irisin levels in paired cerebrospinal fruid (CSF), plasma and their ratio of inpatients, could use as biomarkers, and be independently related to the varying physical dysfunction, muscle wasting severity and chronic diseases with varying severe degrees, remain largely elusive.

METHODS

We conducted an observational study to assess the independent associations between irisin levels in paired cerebrospinal fruid (CSF), plasma and their ratio, and the independence in activities of daily life (ADLs), muscle wasting severity and chronic diseases with varying severe degrees among elderly Chinese in-patient subjects.

RESULTS

Among 217 inpatients in surgery wards with a mean age of 68.07 years (±15.94years), 31.3% of women and 68.7% of men were included in the study. Bivariate correlation analysis showed that Log transformed CSF and plasma irisin levels and their ratio were potential associated with age, fat%, muscle wasting time, ADLs, number of multimorbidity, the severity of bone mass loss and anemia. Regression models analysis indicated that CSF and plasma irisin levels and their ratio in inpatient individuals were independently associated with the independence in ADLs. Plasma irisin levels were independently related to the change of muscle wasting use.

CONCLUSIONS

Collectively, the evaluation of paired plasma and CSF irisin levels, and their ratio in in-patient individuals is intriguing candidates for the susceptibility of the independence in ADLs. Plasma irisin levels were positively associated with indepedence in ADLs, negatively related to muscle wasting severity, and could use as biomarkers for muscle wasting severity.

New Insights into Adipokines as Potential Biomarkers for Type-2 Diabetes Mellitus

A large number of studies have been focused on investigating serum biomarkers associated with risk or diagnosis of type-2 diabetes mellitus. In the last decade, promising studies have shown that circulating levels of adipokines could be used as a relevant biomarker for diabetes mellitus progression as well as therapeutic future targets. Here, we discuss the possible use of recently described adipokines, including apelin, omentin-1, resistin, FGF-21, neuregulin-4 and visfatin, as early biomarkers for diabetes. In addition, we also include recent findings of other well known adipokines such as leptin and adiponectin. In conclusion, further studies are needed to clarify the pathophysiological significance and clinical value of these biological factors as potential biomarkers in type-2 diabetes and related dysfunctions.

Association of irisin and oxidative stress with biochemical parameters in patients with metabolic syndrome

Background Irisin, a hormone-like myokine, is suspected to have a role in metabolic syndrome (MetS) through regulating energy homeostasis and mediating physical activity. In this regard, the role of irisin and malondialdehyde (MDA) along with some other biochemical parameters in the prediction of MetS was examined in the present investigation. Materials and methods In the present case-control study, 36 subjects diagnosed with MetS according to International Diabetes Federation were considered as cases and were matched in age and gender with 31 healthy participants. The difference of biochemical indicators between cases and controls were determined whether by independent t-test or the Mann-Whitney U-test. The predictors of MetS and insulin resistance (IR) were examined through logistic and linear regressions analysis models, respectively. Results Irisin and MDA were not found to be predictors for MetS in logistic regression; p = 0.258 and p = 0.694, respectively. The IR was found to be the only direct predictor of MetS (p = 0.010). Similarly, in linear regression, irisin and MDA were not identified to be predictors for IR; p = 0.801 and p = 0.781, respectively. Conclusions The study did not show that irisin and MDA, directly and indirectly, were predictors of MetS disorder. The IR was only predictor of MetS.

Impact of serum omentin-1 levels on functional prognosis in nondiabetic patients with ischemic stroke

OBJECTIVE

Omentin-1, an adipokine released from visceral fat tissue, is associated with diabetes and stroke. The purpose of this study was to assess the impact of serum omentin-1 levels on functional prognosis in nondiabetic patients with ischemic stroke.

METHODS

From March 2016 to December 2017, consecutive patients with first-ever ischemic stroke admitted to our hospital, China, were recorded. Functional impairment was evaluated at 3-month after admission using the modified Rankin scale (mRS). Uni-and multivariate analyses with Cox proportional hazard regression was used for assessing the relationship between serum level of omentin-1 and functional outcome.

RESULTS

We recorded 209 stroke patients, 52 of them (24.9%) experienced as poor functional outcome. The obtained omentin-1 level in patients with poor outcome was lower than in those patients with good outcome [100.8 (80.9-131.6) ng/ml vs. 137.6 (IQR, 106.1-171.5) ng/ml; Z=4.692; P<0.001). Multivariate analysis models were used to assess stroke outcome according to omentin-1 quartiles (the highest quartile [Q4] as the reference), the 1^st and 2^nd quartile of omentin-1 were compared against the Q4, and the risks were increased by 505% (HR=6.05; 95% CI: 2.13-12.15; P=0.007) and 215% (31.5; 1.21-7.98; P=0.03), respectively. The inclusion of omentin-1 in the routine prediction model for the prediction of poor functional outcome, enhanced the NRI (P=0.006) and IDI (P=0.001) values, confirming the effective reclassification and discrimination. Kaplan-Meier analysis suggested that the patients with low serum omentin-1 levels had a higher risk of death than those patients with high levels of omentin-1 (log-rank test P=0.033).

CONCLUSION

In this cohort of nondiabetic patients with ischemic stroke, a reduced baseline level of serum omentin-1 was related with an increased risk for poor functional outcome or death, independent of baseline variables.

Circulating Irisin Levels in Children With GH Deficiency Before and After 1 Year of GH Treatment

PURPOSE

To evaluate circulating irisin levels in children with GH deficiency (GHD) and any relation with clinical and metabolic parameters.

PATIENTS

Fifty-four prepubertal children (mean age, 7.4 ± 0.8 years) with idiopathic GHD treated with GH for at least 12 months and 31 healthy short children as control subjects.

METHODS

Body height, body mass index (BMI), waist circumference (WC), IGF-I, HbA1c, lipid profile, fasting and after-oral glucose tolerance test glucose and insulin, insulin sensitivity indices, and irisin levels were evaluated at baseline and after 12 months of GH replacement (GHR).

RESULTS

At baseline, children with GHD, in addition to having lower growth velocity (P < 0.001), GH peak after stimulation tests (both P < 0.001), and IGF-I (P < 0.001), showed significantly lower irisin (P < 0.001) and higher BMI (P < 0.001) and WC (P = 0.001), without any difference in metabolic parameters, than control subjects. After GHR, children with GHD showed a significant increase in height (P < 0.001), growth velocity (P < 0.001), IGF-I (P < 0.001), fasting glucose (P = 0.002) and insulin (P < 0.001), homeostasis model assessment estimate of insulin resistance (P < 0.001), and irisin (P = 0.005), with a concomitant decrease in BMI (P = 0.001) and WC (P = 0.003). In multivariate analysis, the independent variables significantly associated with irisin were BMI (P = 0.002) and GH peak (P = 0.037) at baseline and BMI (P = 0.005), WC (P = 0.018), and IGF-I (P < 0.001) during GHR.

CONCLUSIONS

We report that GHR leads to an increase in irisin levels, strongly related to a decrease in BMI and WC, and to an increase in IGF-I; these changes are among the main goals of GHR. These data confirm the favorable effects of GHR in children.

Serum omentin-1 is a novel biomarker for predicting the functional outcome of acute ischemic stroke patients

BACKGROUND

Recent studies have suggested that omentin-1 plays a critical role in the development of cardiovascular disease. However, reported findings are inconsistent, and no study has evaluated the association between omentin-1 levels and a poor functional outcome after ischemic stroke onset.

METHODS

A total of 266 acute ischemic stroke patients were included in this study. All patients were prospectively followed up for 3 months after acute ischemic stroke onset and a poor functional outcome was defined as a major disability or death occurring during the follow-up period. A multivariable logistic model was used to evaluate the association between serum omentin-1 levels and the functional outcome of ischemic stroke patients at 3 months.

RESULTS

Ischemic stroke patients with poor functional outcome had significantly lower levels of serum omentin-1 than patients without poor functional outcome at the 3-month follow-up (50.2 [40.2-59.8] vs. 58.3 [44.9-69.6] ng/mL, p<0.01). Subjects in the highest tertile of serum omentin-1 levels had a 0.38-fold risk of having poor functional outcome, compared with those in the lowest tertile (p<0.05). A negative association between omentin-1 levels and poor functional outcome was found (p for trend=0.02). The net reclassification index was significantly improved in predicting poor functional outcome when omentin-1 data was added to the multivariable logistic regression model.

CONCLUSIONS

Higher omentin-1 levels at baseline were negatively associated with poor functional outcome among ischemic stroke patients. Omentin-1 may represent a biomarker for predicting poor functional outcome of acute ischemic stroke patients.

Serum irisin and apelin levels and markers of atherosclerosis in patients with subclinical hypothyroidism

OBJECTIVE

In this study, we aimed to evaluate serum irisin and apelin levels in patients with subclinical hypothyroidism (SCH) when they were subclinical hypothyroid and become euthyroid after levothyroxine therapy and association of these adipokines with markers of atherosclerosis such as serum homocysteine levels and carotid intima-media thickness (IMT).

SUBJECTS AND METHODS

The study included 160 patients with newly diagnosed subclinical hypothyroidism due to Hashimoto's thyroiditis and 86 euthyroid healty subjects. Serum glucose and lipid profile, insulin, HOMA, TSH, free T3, free T4, anti-thyroperoxidase and anti-thyroglobulin antibodies, homocysteine, apelin and irisin levels were measured in all study subjects. Thyroid and carotid ultrasound examinations were performed. The subclinical hypothyroid group was reevaluated after 12-weeks of levothyroxine therapy when they became euthyroid.

RESULTS

Clinical characteristics of the patient and control group were similar. Glucose, insulin and HOMA levels, lipid parameters and free T3 were similar between the two groups.. Serum homocystein was higher and apelin was lower in patients with SCH, but irisin levels were similar between the two groups. While thyroid volume was lower, carotid IMT was significantly greater in patients with SCH (pCarotidIMT:0,01). After 12-weeks of levothyroxine therapy, all the studied parameters remained unchanged except, serum freeT4, TSH, homocystein and apelin. While homocystein decreased (p: 0,001), apelin increased significantly (p = 0,049). In multivariate analysis, low apelin levels significantly contributed to carotid IMT (p = 0,041).

CONCLUSIONS

Apelin-APJ system may play a role in vascular and cardiac dysfunction in patients with SCH and treatment of this condition may improve the risk of cardiovascular disease.

Associations of Circulating Irisin Concentrations With Cardiometabolic Risk Factors Among Children Vary by Physical Activity or Sedentary Time Levels

Whether irisin concentrations are associated with physical activity (PA) and sedentary time (ST) remains unknown. The role of irisin on cardiometabolic health among children has been contradictory and scarce. This study aimed to examine associations of PA and ST with irisin concentrations and relationships between irisin concentrations and cardiometabolic parameters among children. Additionally, we assessed the interaction between PA or ST and irisin concentrations on cardiometabolic parameters. Basing on a cross-sectional survey of 3,651 general children aged 7-12 years, 575 with different self-reported PA (moderate-vigorous intensity PA ≥ 60 min/day or <150 min/week) and ST (gender-, age-specific ST ≥ 75% or <25% percentile) levels were selected. PA and ST were assessed by the validated international physical activity questionnaires. Fasting blood glucose and lipid profile levels were measured with standard methods by biochemistry analyzer. Plasma irisin concentrations were measured by ELISA. The associations of PA and ST with circulating irisin concentrations were examined by linear regression. Linear regression analysis was also used to estimate associations of circulating irisin concentrations with cardiometabolic variables. Interactions between PA or ST and irisin concentrations on cardiometabolic parameters were calculated using multiple linear regression models with dichotomized factors (low PA and high PA; low ST and high ST). No significant association was observed between circulating irisin concentrations and habitual PA or ST. Irisin concentrations were negatively associated with body mass index (BMI) (β = -0.220), BMI z-score (β = -0.098), waist circumference (β = -0.621), diastolic blood pressure (DBP) (β = -0.561), and triglyceride (β = -0.019) in low PA subgroup, and negatively related to fasting blood glucose (β = -0.040) among high PA subgroup. Moreover, irisin concentrations were negatively associated with BMI (β = -0.157) and fasting blood glucose (β = -0.026) only in high ST subgroup (all P < 0.05). We also observed a significant interaction between PA and irisin concentrations on BMI (P _interaction = 0.0350), BMI z-score (P _interaction = 0.0173), and DBP (P _interaction = 0.0068). In summary, irisin concentrations were not associated with habitual PA or ST in children. The negative associations of irisin concentrations with BMI, BMI z-score, and DBP were found only among children being inactive, implying that irisin may contribute to an improvement in health, especially among children with unhealthy lifestyles.

Myokine-adipokine cross-talk: potential mechanisms for the association between plasma irisin and adipokines and cardiometabolic risk factors in Mexican children with obesity and the metabolic syndrome

BACKGROUND

Adipokines and the myokine irisin, involved in mechanisms associated with obesity and metabolic syndrome (MS), are understudied in the pediatric population.

OBJECTIVE

To investigate the relationship between irisin, and leptin, resistin, adiponectin, adipsin, anthropometric and cardiovascular risk factors in Mexican children.

METHODS

A cross-sample of 126 Mexican children aged 6-12 years old were classified as normal weight (n = 46), obese (n = 40), and MS (n = 40) according to CDC's and Cook's age-modified criteria for obesity and MS. Anthropometric parameters and blood pressure were determined and percentiles calculated for age and gender. Irisin, leptin, adiponectin, adipsin, resistin, triglycerides, glucose, high-density lipoprotein cholesterol (HDL-c) levels, and physical activity were determined. Statistical tests for differences between groups, correlation, and multiple regression analyses were performed.

RESULTS

Irisin plasma levels were significantly lower in the obese (6.08 [4.68-6.65]) and MS groups (6.46 [5.74-7.02]) compared with the normal-weight group (8.05 [7.24-8.94]) (p < 0.001). Irisin levels were not influenced by age or gender, but significant dispersion was observed in obese girls (95% CI median [2.29-6.30]). Leptin, resistin, and adipsin levels were significantly increased in the obese and MS groups. Lean-fat ratio was significantly higher in the NW group. Irisin correlated negatively with leptin (- 0.310), resistin (- 0.389), adipsin (- 0.362), BMI% (-0.472), WC% (- 0.453), BMI z-score (- 0.496), fat free mass (- 0.257), fat percentage (- 0.532), fat mass (- 0.515), triglycerides (- 0.291), the number of cardiometabolic risk factors (- 0.443) (p < 0.001); positively with lean-fat ratio (0.489) and HDL-c (0.328) (p < 0.001) and none with physical activity (p < 0.001). Following stepwise multiple linear regression analysis, the lean-fat ratio was the only determinant of irisin levels (B = 1.168, p < 0.001).

CONCLUSIONS

Lean-fat ratio, more than the absolute amount of muscle or fat mass, as well as potential myokine-adipokine cross-talk mechanisms may explain the lower irisin levels in children with obesity and MS, through blunted compensatory responses interfering with tissue-dependent irisin secretion, contributing to a continuous deleterious effect cycle.

Classic and Novel Adipocytokines at the Intersection of Obesity and Cancer: Diagnostic and Therapeutic Strategies

PURPOSE OF REVIEW

In this review, we investigate the role of classic and novel adipocytokines in cancer pathogenesis synopsizing the mechanisms underlying the association between adipocytokines and malignancy. Special emphasis is given on novel adipocytokines as new evidence is emerging regarding their entanglement in neoplastic development.

RECENT FINDINGS

Recent data have emphasized the role of the triad of overweight/obesity, insulin resistance and adipocytokines in cancer. In the setting of obesity, classic and novel adipocytokines present independent and joint effects on activation of major intracellular signaling pathways implicated in cell proliferation, expansion, survival, adhesion, invasion, and metastasis. Until now, more than 15 adipocytokines have been associated with cancer, and this list continues to expand. While the plethora of circulating pro-inflammatory adipocytokines, such as leptin, resistin, extracellular nicotinamide phosphoribosyl transferase, and chemerin are elevated in malignancies, some adipocytokines such as adiponectin and omentin-1 are generally decreased in cancers and are considered protective against carcinogenesis. Elucidating the intertwining of inflammation, cellular bioenergetics, and adiposopathy is significant for the development of preventive, diagnostic, and therapeutic strategies against cancer. Novel more effective and safe adipocytokine-centered therapeutic interventions may pave the way for targeted oncotherapy.

Decreased Concentration of Irisin Is Associated with Poor Functional Outcome in Ischemic Stroke

Irisin was discovered as a PGC-1a-activated messenger of myocytes that links sedentary lifestyle, obesity, and diabetes. In this study, we investigated the short-term prognostic value of early measurement of irisin concentration in 1530 Han Chinese patients with acute ischemic stroke (AIS) from three stroke centers. The subjects were the first-ever AIS patients who were hospitalized at three stroke centers during the period from January 2015 to December 2016. Clinical information and stroke severity were collected at admission. Neurological evaluations were conducted at the 6-month follow-up. Serum levels of irisin, National Institutes of Health Stroke Scale (NIHSS), and conventional risk factors were evaluated to determine their value to predict functional outcome and mortality within 6 months. Multivariate analyses were performed using logistic regression models. During follow-up, a poor functional outcome was found in 588 patients (38.4%; 95% confidence interval (CI), 36.0-40.9%), and 325 patients died (21.2%; 95% CI, 19.2-23.3%). The stroke patients included in the study were divided into four groups according to irisin quartiles (first is the lowest level). Poor outcome across the irisin quartiles ranged from 54.5% (first quartile) to 21.7% (fourth quartile), and mortality rate ranged from 39.3% (first quartile) to 6.3% (fourth quartile). In a multivariate model using the first quartile (Q1) of irisin vs. Q2-Q4 together with the clinical variables, the marker displayed prognostic information and increased odds ratios of poor outcome by 58% (OR for Q1, 1.58 [95% CI, 1.12-2.43]) and mortality by 185% (OR for Q1, 2.85 [95% CI, 1.79-4.02]). In addition, a model containing known risk factors plus irisin compared with a model containing known risk factors without irisin showed a greater discriminatory ability to predict poor outcome (the area under the curve (AUC) with an increase from 0.73 to 0.75 [95% CI, 0.70-0.81]) and mortality (the AUC increased from 0.80 to 0.83 [95% CI, 0.78-0.87]). Irisin is a novel, independent prognostic marker improving currently used risk stratification of stroke patients. Further studies are needed to confirm this association, which may pave the way to new therapeutic options. Trial registration: ChiCTR-OPC- 17013501.

Irisin Peptide Protects Brain Against Ischemic Injury Through Reducing Apoptosis and Enhancing BDNF in a Rodent Model of Stroke

Evidence has shown therapeutic potential of irisin in cerebral stroke. The present study aimed to assess the effects of recombinant irisin on the infarct size, neurological outcomes, blood-brain barrier (BBB) permeability, apoptosis and brain-derived neurotrophic factor (BDNF) expression in a mouse model of stroke. Transient focal cerebral ischemia was established by middle cerebral artery occlusion (MCAO) for 45 min and followed reperfusion for 23 h in mice. Recombinant irisin was administrated at doses of 0.1, 0.5, 2.5, 7.5, and 15 µg/kg, intracerebroventricularly (ICV), on the MCAO beginning. Neurological outcomes, infarct size, brain edema and BBB permeability were evaluated by modified neurological severity score (mNSS), 2,3,5-triphenyltetrazolium chloride (TTC) staining and Evans blue (EB) extravasation methods, respectively, at 24 h after ischemia. Apoptotic cells and BDNF protein were detected by TUNEL assay and immunohistochemistry techniques. The levels of Bcl-2, Bax and caspase-3 proteins were measured by immunoblotting technique. ICV irisin administration at doses of 0.5, 2.5, 7.5 and 15 µg/kg, significantly reduced infarct size, whereas only in 7.5 and 15 µg/kg improved neurological outcome (P < 0.001). Treatment with irisin (7.5 µg/kg) reduced brain edema (P < 0.001) without changing BBB permeability (P > 0.05). Additionally, irisin (7.5 µg/kg) significantly diminished apoptotic cells and increased BDNF immunoreactivity in the ischemic brain cortex (P < 0.004). Irisin administration significantly downregulated the Bax and caspase-3 expression and upregulated the Bcl-2 protein. The present study indicated that irisin attenuates brain damage via reducing apoptosis and increasing BDNF protein of brain cortex in the experimental model of stroke in mice.

Serum levels of irisin predict short-term outcomes in ischemic stroke

OBJECTIVE

Irisin is a 112-amino acid peptide found in rat and human skeletal muscle after exercise. Previous studies had suggested that higher circulating irisin levels were associated with an increased risk of vascular atherosclerosis and cardiovascular diseases. In this study, we determined irisin levels in serum, and investigated their associations with functional outcomes in a 3-month follow-up study in Chinese patients with first-ever acute ischemic stroke (AIS).

METHODS

From September 2015 to December 2016, consecutive first-ever AIS patients admitted to the Department of Emergency of our hospital were identified. Serum irisin levels were measured at admission. Functional impairment was evaluated at discharge using the modified Rankin scale. The levels of irisin were expressed as median and interquartile ranges [IQR].

RESULTS

The irisin level was obtained in 324 patients (97.6%) with a median value of 291.2 ng/ml (IQR: 214.1-404.2 ng/ml). There were significantly negative correlations between levels of irisin and NHISS (r = -0.272; P < 0.001) and BMI (r = -0.193; P = 0.003). A poor functional outcome was found in 99 patients (30.6%; 95%CI: 25.5-35.6%). The poor functional outcome distribution across the irisin quartiles ranged between 51.9% (first quartile: Q1) to 12.4% (fourth quartile: Q4). In a multivariate model using the Q1 of irisin vs. Q2-4 together with the clinical variables, the marker displayed prognostic information and increased risk of poor outcomes by 94% (OR for Q1, 1.94 [95% CI, 1.19-3.42]; P = 0.018) and mortality 66% (OR for Q1, 1.66 [95% CI, 1.11-3.07]; P = 0.009). In addition, a model containing known risk factors plus irisin compared with a model containing known risk factors without irisin showed a greater discriminatory ability to predict poor outcomes (P = 0.01) and mortality (P = 0.02).

CONCLUSIONS

A low serum irisin level is a predictor of poor early functional outcome in ischemic stroke patients. The underlying mechanisms of these associations remain to be investigated.

Irisin in metabolic diseases

INTRODUCTION

Irisin is a myokine/adipokine induced by the exercise in mice and humans, which is proposed to induce "browning" of white adipose tissue, its primary target, thus increasing thermogenesis and energy expenditure. Since its identification, irisin has been linked to favorable effects on metabolic diseases, including obesity, type 2 diabetes mellitus (T2DM), lipid metabolism and cardiovascular disease (CVD), nonalcoholic fatty liver disease (NAFLD), polycystic ovary syndrome (PCOS), and metabolic bone diseases. Generally, despite the promising profile of irisin in rodents, its effects on human are less recognized.

REVIEW

Most, but not all studies show a positive association between irisin and indices of adiposity. In T2DM, NAFLD, and CVD, most observational studies reported lower irisin levels in patients than controls. Regarding metabolic bone diseases, irisin is positively associated with bone mineral density and strength in athletes, and inversely associated with osteoporotic fractures in postmenopausal osteoporosis. In PCOS, data remain largely conflicting. Irisin does not seem to be further reduced when two metabolic diseases, e.g., T2DM and NAFLD, or obesity and NAFLD exist though more data are needed. Furthermore, it seems that diverse confounders may have affected the results of different clinical studies.

CONCLUSION

Irisin remains an appealing molecule from a pathophysiological point of view and an appealing therapeutic target for metabolic diseases, albeit much research is still needed.

Population-based serum omentin-1 levels: paradoxical association with cardiometabolic disorders primarily in men

AIM

The conflicting relationships of serum omentin with inflammation markers and cardiometabolic disorders were investigated. Results & methods: Unselected 864 population-based middle-aged adults were cross-sectionally studied by sex-specific omentin tertiles. Men in the lowest omentin tertile (T1) had lower systolic blood pressure, HbA1c and glucose values and tended in T3 to higher lipoprotein(a) levels. Logistic regression analysis, adjusted for four covariates, revealed significant independent associations with the presence of hypertension and diabetes only in men. Sex- and age-adjusted odds ratio in gender combined for T2 & T3 versus T1 was 1.34 (95% CI: 1.00-1.79) for metabolic syndrome.

DISCUSSION & CONCLUSION

The elicited adverse relationships of omentin-1 support the notion of oxidative stress-induced proinflammatory conversion of omentin, rendering loss of anti-inflammatory properties.

Omentin-1 is Associated with Carotid Plaque Instability among Ischemic Stroke Patients

Aims: Omentin-1 was proved to be associated with ischemic stroke clinical functional outcome. It also predicted carotid atherosclerosis among metabolic syndrome subjects and type 2 diabetes patients. Our aim was to examine the association of omentin-1 levels with carotid plaque instability and stenosis degree among ischemic stroke patients.

Methods: A total of 173 acute ischemic stroke patients were included in this study. Serum omentin-1 levels were assayed. Carotid ultrasound examinations were performed to evaluate the carotid plaque instability and stenosis degree. Multivariable logistic analyses were used to examine the association of serum omentin-1 levels with carotid plaque instability and stenosis degree.

Results: Ischemic stroke patients with unstable carotid plaque had significantly lower levels of serum omentin-1 than patients with stable plaque (53 [40.2–64.1] vs 61.8 [52.4–77.2] ng/ml, P < 0.01). Subjects in the highest tertile of serum omentin-1 levels had a 0.31-fold risk of having unstable plaque compared with those in the lowest tertile (P < 0.05), and its trend test was significant (P for trend = 0.03). The integrated discrimination improvement was significantly improved in predicting carotid plaque instability when omentin-1 data was added to the multivariable logistic regression model. No significant association was detected between omentin-1 and moderate-severe carotid stenosis or occlusion.

Conclusions: Among ischemic stroke patients, higher omentin-1 levels were inversely associated with carotid plaque instability, but not associated with moderate-severe carotid stenosis or occlusion. Omentin-1 may represent a biomarker for predicting carotid plaque instability of acute ischemic stroke patients.

The relationship between circulating irisin, retinol binding protein-4, adiponectin and inflammatory mediators in patients with metabolic syndrome

OBJECTIVE

We wanted to investigate whether there is a relationship between circulating irisin, retinol binding protein-4 (RBP-4), adiponectin and proinflammatory mediators implicated in the development of insulin resistance (IR) in metabolic syndrome (MetS).

SUBJECTS AND METHODS

In 180 individuals, including controls and patients with MetS, we measured fasting plasma insulin, high sensitivity C-reactive protein (hsCRP), pentraxin-3 (PTX-3), interleukin-33 (IL-33), irisin, RBP-4, and adiponectin using ELISA kits.

RESULTS

While fasting plasma hsCRP, PTX-3, IL-33, irisin, RBP-4 concentrations were higher, adiponectin levels were lower in patients with MetS than in controls. A correlation analysis revealed that plasma irisin levels were positively associated with MetS components such as waist circumference and waist-hip ratio, low density lipoprotein (LDL) and markers of systemic inflammation such as PTX-3, hsCRP, uric acid, and RBP-4. Adiponectin levels were negatively associated with waist circumference, waist-hip ratio, PTX-3 and LDL.

CONCLUSIONS

Although the precise mechanisms are still unclear, irisin, RBP-4, adiponectin and PTX-3 are hallmarks of the MetS, which is related to low-grade inflammation. It is conceivable that irisin and adiponectin might contribute to the development of MetS and may also represent novel MetS components. Future clinical studies are needed to confirm and extend these data.

Omentin-1 effects on mesenchymal stem cells: proliferation, apoptosis, and angiogenesis in vitro

Background

Mesenchymal stem cells (MSCs) are emerging as an extremely promising therapeutic agent for tissue repair. However, limitations exist such as the low numbers of MSCs obtained from donors, and the poor survival and function of donor cells. Omentin-1, a new fat depot-specific secretory adipokine, exerts proproliferation, prosurvival, and proangiogenic functions in certain cells via an Akt-dependent mechanism; however, little is known about the influence of omentin-1 on MSCs.

Methods

MSCs were isolated from 60–80 g donor rats. Cell proliferation was assessed with CCK-8 and EdU assay. Cell cycle, apoptosis ratio, reactive oxygen species concentration, and mitochondrial membrane potential were detected by flow cytometry. Hoechst 33342 dye was used to assess morphological changes of apoptosis. Expression levels of Akt, FoxO3a, GSK-3β, and apoptosis- and cell cycle-associated proteins were detected by Western blotting. Tube formation assay was used to test the angiogenesis role of conditioned medium from MSCs in vitro. The cytokine secretion was assessed by ELISA.

Results

After treatment with omentin-1 (100–800 ng/ml), MSCs displayed a higher proliferative capacity with an increasing number of cells in the S and G2 phase of the cell cycle. Moreover, omentin-1 preconditioning for 1 h could protect MSCs against H₂O₂-induced apoptosis in a concentration-dependent manner. Furthermore, omentin-1 pretreatment reduced the excessive reactive oxygen species. Western blots revealed that increased Bcl-2 and decreased Bax appeared in MSCs after omentin-1 incubation, which inhibited the mitochondrial apoptosis pathways with evidence showing inhibition of caspase-3 cleavage and preservation of mitochondrial membrane potential. Omentin-1 could enhance angiogenic growth factor secretion and elevate the ability of MSCs to stimulate tube formation by human umbilical vein endothelial cells (HUVECs). Furthermore, omentin-1 enhanced Akt phosphorylation; however, blockade of the PI3K/Akt pathway with an inhibitor, LY294002 (20 μM), suppressed the above beneficial effects of omentin-1.

Conclusion

Omentin-1 can exert beneficial effects on MSCs by promoting proliferation, inhibiting apoptosis, increasing secretion of angiogenic cytokines, and enhancing the ability for stimulating tube formation by HUVECs via the PI3K/Akt signaling pathway. Thus, omentin-1 may be considered a candidate for optimizing MSC-based cell therapy.

Association of circulating irisin levels with metabolic and metabolite profiles of Korean adolescents

CONTEXT

Irisin, a novel exercise-induced myokine, has been suggested to regulate energy metabolism.

OBJECTIVE

We studied the relationship between circulating irisin and metabolic and metabolite profiles of Korean adolescents, and investigated the effects of physical activity, obesity, and metabolic syndrome (MetS) on irisin levels.

MATERIALS AND METHODS

Data were obtained from the Korean Children-Adolescents Study. Our cross-sectional study included 618 adolescents (370 normal-weight and 248 obese adolescents; 316 boys and 302 girls) aged 12-15years. Body composition was determined using an impedance body composition analyzer and general participant characteristics and lifestyle information were obtained from questionnaires. Serum irisin levels were measured using a commercial kit.

RESULTS

Mean body mass index (BMI) was 19.4kg/m² in normal-weight adolescents and 31.4kg/m² in obese adolescents. Circulating irisin was positively correlated with adiposity indices, including BMI z-score, waist circumference, percent body fat, fat mass, fat-free mass, fat mass to fat-free mass ratio, and lipid and glucose metabolism markers, including total cholesterol, low-density lipoprotein cholesterol (LDL-C), triglycerides, glucose, insulin, and homeostasis model assessment-estimated insulin resistance (all p≤0.006). Of these, increased body fat mass [standardized (Std) ß, 0.23; p<0.0001], LDL-C (Std ß, 0.14; p=0.0005) and fasting glucose (Std ß, 0.08; p=0.0383) were the main independent factors associated with higher irisin levels. Moreover, elevated serum irisin was associated with the risk of obesity [odds ratio (OR], 2.2; confidence interval (CI), 1.19-3.87] and MetS (OR, 2.0; CI, 1.15-3.47). Furthermore, irisin and branched-chain amino acids were positively associated (p<4×10^-4 for Bonferroni correction). Additionally, in the normal-weight group, girls had higher irisin levels than boys (p=0.006) and adolescents who engaged in regular physical activity had higher levels of irisin than sedentary adolescents (p=0.0388). The relationship between physical activity and irisin levels was not observed in obese adolescents.

CONCLUSIONS

Elevated serum irisin was independently associated with the risk of obesity and positively correlated with unhealthy metabolic parameters and metabolites. Moreover, irisin levels were higher in active versus sedentary adolescents in the normal-weight group, but not in the obese group. Our findings suggest that irisin plays an important role in metabolic disorders and may be affected by physiopathological status.

Adipose Tissue-Derived Omentin-1 Function and Regulation

Omentin-1, also known as intelectin-1, is a recently identified novel adipocytokine of 313 amino acids, which is expressed in visceral (omental and epicardial) fat as well as mesothelial cells, vascular cells, airway goblet cells, small intestine, colon, ovary, and plasma. The level of omentin-1 expression in (pre)adipocytes is decreased by glucose/insulin and stimulated by fibroblast growth factor-21 and dexamethasone. Several lines of experimental evidence have shown that omentin-1 plays crucial roles in the maintenance of body metabolism and insulin sensitivity, and has anti-inflammatory, anti-atherosclerotic, and cardiovascular protective effects via AMP-activated protein kinase/Akt/nuclear factor-κB/mitogen-activated protein kinase (ERK, JNK, and p38) signaling. Clinical studies have indicated the usage of circulating omentin-1 as a biomarker of obesity, metabolic disorders including insulin resistance, diabetes, and metabolic syndrome, and atherosclerotic cardiovascular diseases. It is also possible to use circulating omentin-1 as a biomarker of bone metabolism, inflammatory diseases, cancers, sleep apnea syndrome, preeclampsia, and polycystic ovary syndrome. Decreased omentin-1 levels are generally associated with these diseases. However, omentin-1 increases to counteract the acute phase after onset of these diseases. These findings indicate that omentin-1 may be a negative risk factor for these diseases, and also act as an acute-phase reactant by its anti-inflammatory and atheroprotective effects. Therapeutic strategies to restore omentin-1 levels may be valuable for the prevention or treatment of these diseases. Weight loss, olive oil-rich diet, aerobic training, and treatment with atorvastatin and antidiabetic drugs (metformin, pioglitazone, and exenatide) are effective means of increasing circulating omentin-1 levels. This review provides insights into the potential use of omentin-1 as a biomarker and therapeutic target for these diseases. © 2017 American Physiological Society. Compr Physiol 7:765-781, 2017.

Elevated serum tartrate-resistant acid phosphatase isoform 5a levels in metabolic syndrome

Background

Tartrate-resistant phosphatase isoform 5a is expressed in tumor-associated macrophages and is a biomarker of chronic inflammation. Herein, we correlated serum tartrate-resistant phosphatase isoform 5a levels with metabolic syndrome status and made comparisons with traditional markers of inflammation, including c-reactive protein and interleukin-6.

Methods

One hundred healthy volunteers were randomly selected, and cut-off points for metabolic syndrome related inflammatory biomarkers were determined using receiver operating characteristic curves. Linear and logistic regression models were subsequently used to correlate inflammatory markers with the risk of metabolic syndrome.

Results

Twenty-two participants met the criteria for metabolic syndrome, and serum tartrate-resistant phosphatase isoform 5a levels of >5.8 μg/L were associated with metabolic syndrome (c-statistics, 0.730; p = 0.001; 95% confidence interval, 0.618-0.842). In addition, 1 μg/L increases in tartrate-resistant phosphatase isoform 5a levels were indicative of a 1.860 fold increase in the risk of metabolic syndrome (p = 0.012).

Conclusions

Elevated serum tartrate-resistant phosphatase isoform 5a levels are associated with the risk of metabolic syndrome, with a cut-off level of 5.8 μg/L.

Relation of serum irisin level with metabolic and antropometric parameters in obese children

OBJECTIVE

This study aimed to investigate the relationship between serum irisin level and metabolic and anthropometric parameters in obese children.

METHODS

The study included 36 obese children with a body mass index (BMI) of ≥95th percentile and 30 healthy children with a BMI ranging from the 5th to the 85th percentile. Healthy and obese children had similar age, gender and pubertal stage distribution. Anthropometric and biochemical parameters (fasting glucose, insulin, lipid profile, leptin and irisin levels) were measured. Bioelectric impedance analysis was used to determine the body composition parameters, including body fat percentage and fat mass.

RESULTS

Serum irisin and leptin levels of the obese children were significantly higher than those of the healthy children [median irisin levels, 141.2 & 107.6ng/mL, p=0.024; median leptin levels, 10.9 & 2.9pg/mL, P<0.001, respectively). No statistically significant difference was found when leptin and irisin levels were compared among obese patients in terms of the presence of insulin resistance. Irisin levels significantly correlated with high-density lipoprotein cholesterol (HDL-C), fasting insulin and homeostasis model assessment-insulin resistance (HOMA-IR) with adjustment for age and BMI. The multivariate regression analysis showed that age, HOMA-IR and HDL-C had a significant association with the serum irisin level, which explained 30.6% of the variance.

CONCLUSION

This study demonstrated that obese children had significantly higher irisin levels than healthy children. Additionally, it provides evidence regarding the role of irisin on insulin sensitivity and lipid metabolism in childhood obesity.

Central inhibitory effects on feeding induced by the adipo-myokine irisin

Irisin, the soluble secreted form of fibronectin type III domain containing 5 (FNDC5)-cleaved product, is a recently identified adipo-myokine that has been indicated as a possible link between physical exercise and energetic homeostasis. The co-localization of irisin with neuropeptide Y in hypothalamic sections of paraventricular nucleus, which receives NPY/AgRP projections from the arcuate nucleus, suggests a possible role of irisin in the central regulation of energy balance. In this context, in the present work we studied the effects of intra-hypothalamic irisin (1μl, 50-200nmol/l) administration on feeding and orexigenic [agouti-related peptide (AgRP), neuropeptide Y (NPY) and orexin-A] and anorexigenic [cocaine and amphetamine-regulated transcript (CART) and proopiomelanocortin (POMC)] peptides in male Sprague-Dawley rats. Furthermore, we evaluated the effects of irisin on hypothalamic dopamine (DA), norepinephrine (NE) and serotonin (5-hydroxytryptamine, 5-HT) concentrations and plasma NE levels. Compared to vehicle, irisin injected rats showed decreased food intake, possibly mediated by stimulated CART and POMC and inhibited DA, NE and orexin-A, in the hypothalamus. We also found increased plasma NE levels, supporting a role for sympathetic nervous system stimulation in mediating increased oxygen consumption by irisin.

Novel Molecules Regulating Energy Homeostasis: Physiology and Regulation by Macronutrient Intake and Weight Loss

Excess energy intake, without a compensatory increase of energy expenditure, leads to obesity. Several molecules are involved in energy homeostasis regulation and new ones are being discovered constantly. Appetite regulating hormones such as ghrelin, peptide tyrosine-tyrosine and amylin or incretins such as the gastric inhibitory polypeptide have been studied extensively while other molecules such as fibroblast growth factor 21, chemerin, irisin, secreted frizzle-related protein-4, total bile acids, and heme oxygenase-1 have been linked to energy homeostasis regulation more recently and the specific role of each one of them has not been fully elucidated. This mini review focuses on the above mentioned molecules and discusses them in relation to their regulation by the macronutrient composition of the diet as well as diet-induced weight loss.