Adiponectin profile and Irisin expression in Italian obese children: Association with insulin-resistance

Examining the mediating role of muscle quantity in adolescents: associations with adiposity, cardiorespiratory fitness, muscular fitness, and cardiometabolic risk factors

The aim of this study was to evaluate the mediation role of muscle quantity in the relationship between physical fitness and cardiometabolic risk factors (CMRF) in adolescents. This cross-sectional study conducted with 120 adolescents of both sexes, aged between 10 and 17 years. Body mass, height, fat mass (FM), lean mass, blood pressure, high-density lipoprotein, low-density lipoprotein, triglycerides, glucose, insulin, cardiorespiratory fitness (CRF) and 1 repetition maximum strength (1-RM) with evaluation of the leg press 45° (RM-leg), bench press (RM-bench) and arm curl (RM-arm). Body mass index z-score, appendicular skeletal muscle mass, appendicular skeletal muscle mass index, lean mass index (LMI), muscle-to-fat ratio (MFR), age at peak height velocity, and CMRF z-score were calculated. The direct relation between FM and CMRF was mediated by the LMI (26%) and inverse relation between CRF and CMRF was mediated by the LMI (26%). For girls, the direct relation between FM and CMRF was mediated by the LMI (32%); the inverse relation between CRF, RM-leg, RM-arm and CMRF was mediated by the LMI (32%, 33%, and 32%, respective). For boys, the indirect effect was not significant, indicating that LMI is not a mediator in the relation between FM, CRF, 1-RM with CMRF. The direct relation between RM-leg and CMRF was mediated by the MRF (16%). This finding evidenced the importance of promoting a healthy lifestyle to improve physical fitness levels and the quantity of muscle mass in adolescents.

HIF1α Elevations at Tissue and Serum Levels and Their Association With Metabolic Disorders in Children With Obesity

OBJECTIVE

We aimed to examine the expression profile and circulating level of hypoxia-inducible factor 1 alpha (HIF1α) in children and the relationships with metabolic disorders.

METHODS

A total of 519 children were recruited, with paired subcutaneous and omental adipose tissues collected from 17 children and serum samples from the remaining children. All children underwent anthropometric and biochemical analyses. The mRNA, protein, and serum levels of HIF1α were determined by real-time PCR, immunohistochemistry, and enzyme-linked immunosorbent assay, respectively.

RESULTS

Both HIF1α mRNA and protein levels, especially in omental adipose tissue, were increased in overweight or obese (OV/OB) children (P < .05). Likewise, serum HIF1α level was remarkably higher in OV/OB children than in normal-weight children (P < .05). Serum HIF1α level was positively correlated with BMI z-score, fat mass percentage, waist to height ratio, systolic blood pressure, alanine aminotransferase, total triglycerides, uric acid, and homeostasis model assessment of insulin resistance (IR). Furthermore, a binary logistic regression analysis of serum HIF1α level indicated that the risks for IR, nonalcoholic fatty liver disease (NAFLD), and metabolic syndrome remained significant in the presence of all potential confounding variables. Finally, the area under the receiver operating characteristic curves for serum HIF1α level in children who were diagnosed with IR, NAFLD, and metabolic syndrome were 0.698 (95% CI, 0.646-0.750; P < .001), 0.679 (95% CI, 0.628-0.731; P < .001), and 0.900 (95% CI, 0.856-0.945; P < .001).

CONCLUSION

HIF1α expression is higher in the adipose tissue, especially omental, of children with obesity than in children with normal weight. Elevated serum HIF1α level is associated with adiposity and metabolic disorder, which may predict a higher risk of obesity complications.

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.

Association of Serum Irisin Levels with Body Composition, Metabolic Profile, Leptin, and Adiponectin Levels in Lean and Obese Children

Background and Objectives: Irisin is an adipo-myokine with potential metabolic effects in the body, and its association with childhood obesity is still controversial. This study aimed to investigate the relationship between serum irisin levels and anthropometric parameters, body composition, metabolic profiles, leptin, and adiponectin in obese and normal-weight children. Methods: The study sample consisted of a total of 80 children aged 6-10, including 44 obese children (BMI ≥ 97th percentile) and 36 normal-weight children. Anthropometric parameters were measured. Body composition was determined with the use of the Bioelectrical Impedance Analysis (BIA) method. Metabolic profiles, as well as irisin, leptin, and adiponectin levels, were analyzed. Results: Anthropometric parameters and body composition were found to be significantly different between the obese and normal-weight groups (p < 0.05). Fasting blood glucose, insulin, HOMA-IR, and leptin levels were found to be significantly higher in the obese group, while the normal-weight group had significantly higher HDL cholesterol and adiponectin levels (p < 0.05). Serum irisin levels did not differ between the obese and normal-weight groups, or based on sex, vitamin D levels, and insulin resistance status. There was also no statistically significant correlation between serum irisin levels and anthropometric parameters, metabolic profile, leptin, and adiponectin. Conclusions: The study concluded that the obese children who participated in this study had high leptin levels and low adiponectin levels, with no significant difference in the irisin levels between the groups. More comprehensive clinical studies are needed to investigate the relationship between irisin and adipokines in children.

Impact of Paleo Diet on Body Composition, Carbohydrate and Fat Metabolism of Professional Handball Players

The Paleo diet (PD) involves a restriction of carbohydrates and increased fat content (35% energy from carbohydrates, 35% energy from fats and 30% energy from protein). The aim of this study was to examine the effect of the PD on body composition, concentration of carbohydrates and lipids, as well as insulin, irisin, adiponectin and leptin in the blood. A total of 25 handball players were assigned to two groups: 14 in the experimental group (PD) and 11 in the control group (CD), using a PD and a rational diet, respectively. Analysis of body mass and body composition (body mass index, fat mass, lean body mass, fat-free mass, muscle mass, bone mineral content and bone mineral density), as well as blood concentration of metabolism markers (glucose, insulin, total cholesterol, HDL-cholesterol, non-HDL-cholesterol, LDL-cholesterol, triglycerides, free fatty acids, β-hydroxybutyrate, irisin, adiponectin and leptin), were determined at the beginning and after 4 and 8 weeks of nutritional intervention. Body mass was lower (p < 0.01), and adiponectin blood concentration was higher (p = 0.03) in the PD group at the end of the intervention. There were no changes (p ≥ 0.05) in body composition and blood levels of other biochemical markers in either group.

High molecular weight adiponectin as a biomarker of hypertension in children and adolescents with obesity

Lower HMW (high molecular weight) adiponectin levels are associated with obesity, insulin resistance, and metabolic syndrome in children and adolescents. However, data on HMW levels in pediatric population with hypertension are lacking. This study aimed to examine the association and predictive capacity of HMW levels, HMW/HOMA-IR, and HMW/APN ratio with hypertension in obese children and adolescents. The 299 pediatric subjects were grouped in obese hypertensive (OH), obese normotensive (ON), and normal weight normotensive (NN). Plasma concentrations of HMW were investigated by ELISA. ANOVA was used to compare study groups, and a binary logistic regression analysis was used to verify if HMW, HMW/HOMA-IR, HMW/APN, APN, APN/HOMA-IR, and HOMA-IR are associated to hypertension regardless obesity in children and adolescents. To compare the strength and performance of each biomarker to classify individuals with and without hypertension, the receiver-operating characteristic (ROC) curve, area under the curve (AUC), and Youden index (J) were evaluated. Both HMW plasma levels and the HMW/HOMA-IR ratio were significantly lower in the OH group when compared to the ON group (HMW: 2.00 ± 1.33 µg/mL vs 2.48 ± 1.48 µg/mL; HMW/HOMA-IR ratio: 0.87 ± 0.95 vs 1.27 ± 1.2; P < 0.05) and NN weight groups (HMW: 2.00 ± 1.33 µg/mL vs 4.02 ± 1.99 µg/mL; HMW/HOMA-IR ratio: 0.87 ± 0.95 vs 2.62 ± 1.86; P < 0.05). Hypertension was associated with lowest HMW (OR = 4.50; 95% CI = 1.41-15.84) and HMW/HOMA-IR (OR = 12.13; 95% CI = 2.51-92.93) regardless of obesity. However, HOMA-IR or the HMW/APN was not significant (P > 0.05). In the ROC curve analyses, the HMW and HMW/HOM-IR were more sensitive to detect hypertension in children and adolescents with obesity.    Conclusion: Low levels of HMW oligomer and HMW/HOM-IR are associated with hypertension in childhood obesity. Thus, these biomarkers could be clinically useful in identifying hypertension in childhood obesity. What is Known: • HMW has previously been reported as the most biologically active isoform of adiponectin, and lower HMW concentrations are associated with obesity, insulin resistance, and metabolic syndrome in children and adolescents. • HMW/HOMA-IR ratio is a sensitive predictor for metabolic syndrome in adults. What is New: • HMW levels are associated with hypertension in children and adolescents, independently of presence of obesity. • HMW was more sensitive to detect hypertension in children and adolescents with obesity when compared to HMW/HOMA-IR, HMW/APN, APN, APN/HOMA-IR, or HOMA-IR.

Contribution of organokines in the development of NAFLD/NASH associated hepatocellular carcinoma

Globally the incidence of hepatocellular carcinoma (HCC) is on an upsurge. Evidence is accumulating that liver disorders like nonalcoholic fatty liver disease (NAFLD) and its more progressive form nonalcoholic steatohepatitis (NASH) are associated with increased risk of developing HCC. NAFLD has a prevalence of about 25% and 50%-90% in obese population. With the growing burden of obesity epidemic worldwide, HCC presents a major healthcare burden. While cirrhosis is one of the major risk factors of HCC, available literature suggests that NAFLD/NASH associated HCC also develops in minimum or noncirrhotic livers. Therefore, there is an urgent need to understand the pathogenesis and risk factors associated with NAFLD and NASH related HCC that would help in early diagnosis and favorable prognosis of HCC secondary to NAFLD. Adipokines, hepatokines and myokines are factors secreted by adipocytes, hepatocytes and myocytes, respectively, playing essential roles in cellular homeostasis, energy balance and metabolism with autocrine, paracrine and endocrine effects. In this review, we endeavor to focus on the role of these organokines in the pathogenesis of NAFLD/NASH and its progression to HCC to augment the understanding of the factors stimulating hepatocytes to acquire a malignant phenotype. This shall aid in the development of novel therapeutic strategies and tools for early diagnosis of NAFLD/NASH and HCC.

Serum irisin levels increase in girls with central precocious puberty not dependent on BMI: a pilot study

OBJECTIVE

The objective of this study is to investigate the role of serum irisin level in diagnosis of central precocious puberty (CPP) in girls and its major determinants.

METHODS

This study was conducted in 67 girls with CPP, 19 girls with premature thelarche (PT) and 59 normal controls. The major determinants of irisin were assessed by multivariate linear regression (MLR) analysis. Propensity score matching (PSM) analysis was performed to minimize the bias that can result from BMI. A receiver operating characteristic curve was used to obtain the optimal threshold value of irisin.

RESULTS

The girls with CPP and PT had higher irisin levels than controls (P < 0.05). The optimal cutoff value of irisin levels for predicting CPP was 91.88 ng/mL, with a sensitivity of 70.1% and a specificity of 72.9%. MLR analysis showed that BMI was a predictor of irisin (P < 0.05). Serum irisin levels remained higher in the CPP girls than the controls with adjustment for BMI (P < 0.05).

CONCLUSIONS

Increased serum irisin levels with CPP suggest that irisin is involved in puberty. However, due to low sensitivity and specificity, irisin level can only be used as an auxiliary indicator rather than a single diagnostic indicator of CPP.

Serum Fatty Acid-Binding Protein 4 Levels in Adolescents: Effect of Insulin Resistance

Background: Fatty acid-binding protein 4 (FABP4) is an adipokine that plays a causative role in obesity and diabetes. In a stratified cross-sectional study with adolescents, we explored whether changes in FABP4 are already present in lean adolescents, provided they display elements of insulin resistance (IR). Methods: Adolescents were divided in four groups according to body mass index and homeostasis model assessment-IR. Results: In metabolically unhealthy lean (MUL) adolescents (MUL, lean with IR), FABP4 was 33% higher than in healthy counterparts (metabolically healthy lean [MHL]). Obese adolescents without IR (metabolically healthy obesity [MHO]) had 50% higher levels of FABP4 than their lean counterparts (MHL), while levels of FABP4 in obese adolescents with IR (metabolically unhealthy obese [MUO]) were 220% higher than those of MUL adolescents. The differences were significant at least with P < 0.005. MUO > MHO > MUL. Our data demonstrate that the known FABP4 defect in adults with obesity also occurs in youth and even in lean adolescents, suggesting an early association between impaired glucose metabolism and FABP4 irrespective of body weight. FABP4 was more sensitive in discerning each of our 4 subgroups than either adiponectin or leptin. Moreover, evidence for a putative early adiponectin resistance in MUL suggests a combined defect in these adolescents that call for early detection and prevention of the metabolic disturbance that should stay away from concentrating only in subjects with obesity. Conclusions: Our data may serve to draw the considerable attention that is currently paid to FABP4 to the adolescent population, irrespective of the presence of obesity. Further studies with larger cohorts and analyses of visceral and liver fat are warranted.

Circulating Irisin in Children and Adolescents With Prader-Willi Syndrome: Relation With Glucose Metabolism

Irisin is a myokine involved in the browning of white adipose tissue and regulation of energy expenditure, glucose homeostasis and insulin sensitivity. Debated evidence exists on the metabolic role played by irisin in children with overweight or obesity, while few information exist in children with Prader Willi Syndrome (PWS), a condition genetically prone to obesity. Here we assessed serum irisin in relation to the metabolic profile and body composition in children and adolescents with and without PWS. In 25 PWS subjects [age 6.6-17.8y; body mass index standard deviation score (BMI SDS) 2.5 ± 0.3] and 25 age, and BMI-matched controls (age 6.8-18.0y; BMI SDS, 2.8 ± 0.1) we assessed irisin levels and metabolic profile inclusive of oral glucose tolerance test (OGTT), and body composition by dual-energy X-ray absorptiometry (DXA). In PWS, we recorded lower levels of fat-free mass (FFM) (p <0.05), fasting (p<0.0001) and 2h post-OGTT insulin (p<0.05) and lower insulin resistance as expressed by homeostatic model of insulin resistance (HOMA-IR) (p<0.0001). Irisin levels were significantly lower in PWS group than in controls with common obesity (p<0.05). In univariate correlation analysis, positive associations linked irisin to insulin OGTT₀ (p<0.05), insulin OGTT₁₂₀ (p<0.005), HOMA-IR (p<0.05) and fasting C-peptide (p<0.05). In stepwise multivariable regression analysis, irisin levels were independently predicted by insulin OGTT₁₂₀. These results suggest a link between irisin levels and insulin sensitivity in two divergent models of obesity.

In Vitro and In Vivo Antidiabetic Potential of Monoterpenoids: An Update

Diabetes mellitus (DM) is a chronic metabolic condition characterized by persistent hyperglycemia due to insufficient insulin levels or insulin resistance. Despite the availability of several oral and injectable hypoglycemic agents, their use is associated with a wide range of side effects. Monoterpenes are compounds extracted from different plants including herbs, vegetables, and fruits and they contribute to their aroma and flavor. Based on their chemical structure, monoterpenes are classified into acyclic, monocyclic, and bicyclic monoterpenes. They have been found to exhibit numerous biological and medicinal effects such as antipruritic, antioxidant, anti-inflammatory, and analgesic activities. Therefore, monoterpenes emerged as promising molecules that can be used therapeutically to treat a vast range of diseases. Additionally, monoterpenes were found to modulate enzymes and proteins that contribute to insulin resistance and other pathological events caused by DM. In this review, we highlight the different mechanisms by which monoterpenes can be used in the pharmacological intervention of DM via the alteration of certain enzymes, proteins, and pathways involved in the pathophysiology of DM. Based on the fact that monoterpenes have multiple mechanisms of action on different targets in in vitro and in vivo studies, they can be considered as lead compounds for developing effective hypoglycemic agents. Incorporating these compounds in clinical trials is needed to investigate their actions in diabetic patients in order to confirm their ability in controlling hyperglycemia.

Serum levels of irisin in postmenopausal women with osteoporotic hip fractures

OBJECTIVE

The purpose of this study was to evaluate the role of circulating serum levels of irisin in predicting hip fracture occurrence in a cohort of Chinese postmenopausal women.

METHODS

This was a cross-section and case-control study. Four hundred and thirty postmenopausal women aged 50-90 years were included (215 with hip fractures and 215 age-matched cases without fracture). Clinical features, bone mineral density (BMD) and serum biomarkers levels including irisin were measured at baseline. Cox proportional hazards regression analysis was used to assess the correlation between irisin and fracture risk.

RESULTS

The mean age of those participants was 68.7 (S.D. 11.7) and 53.0% were order than 65. The irisin serum levels were positively related to total body BMD and total hip BMD. Women with hip fractures showed lower mean serum levels of irisin compared normal control women (457.6 ± 172.6 ng/ml vs. 602.2 ng/ml; P < 0.001). The irisin levels in third and fourth quartiles were associated with the risk of hip fracture (the lowest quartile of irisin levels as the reference), and risk of fracture reduced by 67% (hazard ratio [HR] = 0.33; 95 %CI: 0.18-0.54; P < 0.001) and 84% (HR = 0.16; 95 %CI: 0.09-0.29; P < 0.001). The irisin levels in third and fourth quartiles were also associated with the risk of osteoporosis, and risk of fracture reduced by 55% (HR = 0.45; 95 %CI: 0.21-0.63; P = 0.003) and 73% (HR = 0.27; 95 %CI: 0.15-0.47; P < 0.001).

CONCLUSION

Decreased serum levels of circulating irisin are associated with high risk of osteoporosis-related hip fractures and osteoporosis.

Emerging evidence for the opposite role of circulating irisin levels and brown adipose tissue activity measured by infrared thermography in anthropometric and metabolic profile during childhood

Irisin is an adipomyokine that increases browning of adipose tissue and thermogenesis, thereby protecting against obesity and insulin resistance. However, the correlation between irisin, brown adipose tissue (BAT), and childhood obesity, as well as its association with an increased risk of developing metabolic diseases, has not been completely elucidated. This study aimed to investigate the association between irisin levels and BAT activity measured by infrared thermography among children and verify their correlation with anthropometric and metabolic parameters. This study included 42 children with normal weight and 18 overweight/obese children. Anthropometric data, irisin levels, lipid and glucose profile were evaluated. The percentage of the thermally active portion of the supraclavicular area (%Area_SCR) before and after a cold stimulus was measured by infrared thermography, and the differences between the percentages of thermally active (Δ%Area_SCR) was calculated as an index of BAT activation. The results were correlated with anthropometric and metabolic parameters. Circulating irisin levels was positive correlated with age (rho=0.327, P= 0.011), body mass index (BMI) (rho=0.707, P<0.001), waist circumference (rho=0.624, P<0.001), total cholesterol (rho=0.361, P=0.044), triglycerides (rho=0.419, P=0.001), and low-density lipoprotein cholesterol (LDLc) (rho=0.381, P= 0.003). Active BAT was negatively correlated with BMI, waist circumference, triglycerides, LDLc and irisin levels. We observed that normal weight children increased significantly the Δ% Area_SCR as compared to overweight/obese children. In conclusion, circulating irisin levels and BAT activity appear to have opposing roles, since normal weight children had greater BAT activity and lower circulating levels of irisin.

The Effect of a Life-Style Intervention Program of Diet and Exercise on Irisin and FGF-21 Concentrations in Children and Adolescents with Overweight and Obesity

Overweight and obesity in childhood and adolescence represent major public health problems of our century, and account for increased morbidity and mortality in adult life. Irisin and Fibroblast Growth Factor 21 (FGF-21) have been proposed as prognostic and/or diagnostic biomarkers in subjects with obesity and metabolic syndrome, because they increase earlier than other traditional biomarkers. We determined the concentrations of Irisin and FGF-21 in children and adolescents with overweight and obesity before and after one year of a life-style intervention program of diet and physical exercise and explored the impact of body mass index (BMI) reduction on the concentrations of Irisin, FGF-21 and other cardiometabolic risk factors. Three hundred and ten (n = 310) children and adolescents (mean age ± SD: 10.5 ± 2.9 years) were studied prospectively. Following one year of the life-style intervention program, there was a significant decrease in BMI (p = 0.001), waist-to-hip ratio (p = 0.024), waist-to-height ratio (p = 0.024), and Irisin concentrations (p = 0.001), and an improvement in cardiometabolic risk factors. There was no alteration in FGF-21 concentrations. These findings indicate that Irisin concentrations decreased significantly as a result of BMI reduction in children and adolescents with overweight and obesity. Further studies are required to investigate the potential role of Irisin as a biomarker for monitoring the response to lifestyle interventions and for predicting the development of cardiometabolic risk factors.

The relationship of irisin with metabolic syndrome components and insulin secretion and resistance in schoolchildren

Irisin, a novel myokine, is believed to be the crucial factor in converting white adipose tissue to beige adipose tissue. For this paper, we studied the relationship among irisin and components of metabolic syndrome (MetS), and insulin secretion and resistance in schoolchildren of Taiwan.Subjects receiving routine annual health examination at elementary school were enrolled. Demographic data, anthropometry, MetS components, irisin, and insulin secretion and resistance were collected. Subjects were divided into normal, overweight, and obese groups for evaluation of irisin in obesity. Finally, the relationship between irisin and MetS was analyzed.There were 376 children (179 boys and 197 girls), aged 10.3 ± 1.5 years, were enrolled. In boys, irisin levels were not associated with body mass index percentile, body fat, blood pressure, lipid profiles, insulin secretion or resistance. After adjusting for age, the irisin level in boys was negatively related to fasting plasma glucose (FPG) (r = -0.21, P = .006). In girls, after adjusting for age, the irisin levels were positively related only to FPG (r = 1.49, P = .038). In both genders, irisin levels were similar among normal, overweight, and obese groups, and between subjects with and without MetS.The irisin levels were not associated with MetS in either boys or girls. In girls, circulating irisin levels have a nonsignificant declining trend in overweight and obese girls. However, irisin levels were negatively related to FPG in boys and positively related to FPG in girls. The contrary relationship between irisin and FPG in boys and girls needs further exploration.

Dietary quality score is positively associated with serum adiponectin level in Indonesian preschool-age children living in the urban area of Jakarta

An unhealthy diet during childhood directly impacts the risk of developing noncommunicable diseases (NCDs) later on in life. However, well-documented information on this issue is lacking. We investigated the dietary quality of young Indonesian children and assessed the relationship to serum adiponectin levels as an early marker of NCDs. Eighty-five (44 girls and 41 boys) Indonesian preschool-age children in East Jakarta were included in this study. Dietary intake data were gathered by collecting repeated 24-hour recalls for one weekday and one day during the weekend, which were then further converted into participants' Healthy Eating Index (HEI) 2015 scores. Meanwhile, an enzyme-linked immunosorbent assay was performed to determine the serum adiponectin level. A multiple regression analysis was performed to assess the association between the HEI 2015 score and serum adiponectin, adjusting for potential confounders. The mean HEI 2015 score was 33.2 ± 8.3 points, which was far below the recommended score of ≥ 80 points, while the mean serum adiponectin was 10.3 ± 4.1 μg/mL. Multiple linear regression testing showed that a one-point increase in the HEI 2015 score was significantly associated with an increase in the serum adiponectin level by 0.115 μg/mL after adjusting for exclusive breastfeeding history (β = 0.115; 95% CI = 0.010-0.221; p = 0.032). In conclusion, better adherence of young children to a healthy diet has a positive association with their adiponectin level. This result suggests that strengthening children's dietary quality from an early age by involving all parties in the children's environment (e.g., parents, teachers at school, policymakers) may help to reduce the risk of NCDs later on in childhood and during adult life.

Relationships Between Circulating Irisin Response to Ice Swimming and Body Composition in People With Regular Exercise Experience

Severe cold exercise involves the irisin response, and may be related to body composition. We aimed to investigate changes in circulating irisin after ice swimming (IS), as well as to evaluate the correlation between body composition and the change in irisin caused by IS (Δirisin). 81 ice swimmers were recruited to perform IS activities. Blood samples were drawn 30 min before and 30 min after IS, and the serum levels of irisin and the ice swimmers' body composition were measured. As results, circulating irisin declined significantly during the recovery period following IS exercise (P < 0.001). The afternoon baseline circulating irisin level and Δirisin in response to IS were correlated with body fat characteristics rather than muscle parameters in ice swimmers. Δirisin subgroup analyses showed that the Δirisin ascending group (Δirisin+) subjects had a higher fat composition and higher basal irisin levels than the Δirisin descending group (Δirisin-). Furthermore, the decrease in irisin was negatively correlated with fat components in Δirisin- subjects, whereas no correlation was observed between the increase in irisin and body composition in Δirisin + subjects. Finally, a non-linear association analysis suggested that body fat indicators had obvious curvilinear relationships with Δirisin. In conclusion, IS caused a significant decrease in irisin. Statistical and curvilinear associations suggested that the correlation between fat tissue and Δirisin caused by IS is dimorphic and the underlying mechanisms may be due to the different metabolic states of subjects.

Serum Irisin Levels in Central Precocious Puberty and Its Variants

AIM

The exact mechanisms that trigger the onset of puberty are not well known. Adipomyokines are postulated to stimulate the central neural network. In the present study, we investigated irisin levels in girls with central precocious puberty (CPP), slowly progressing precocious puberty (SPPP), or premature thelarche (PT); we also studied prepubertal girls and to determine if this adipomyokine could be used as a marker in this context.

METHODS

A total of 94 girls including 33 with CPP, 31 with precocious puberty (PP) variants (SPPP or PT), and 30 healthy controls were enrolled to the study. The mean irisin levels were compared between groups. The bivariate correlations of irisin levels with clinical and laboratory parameters were assessed. Multivariate linear regression analysis was performed to determine independent predictive factors of irisin levels.

RESULTS

Irisin levels were higher in the CPP group compared with the other groups (CPP group: 723.25 ± 62.35 ng/mL; PP variants group: 529.60 ± 39.66 ng/mL; and control group: 325.03 ± 27.53 ng/mL) (P < 0.001). Irisin levels were positively correlated with body mass index standard deviation scores (BMI-SDS), height-SDS, weight-SDS, bone age, uterus long axis, ovary size, baseline FSH and LH, and peak LH levels. Multivariate linear regression analysis revealed that irisin levels had the strongest correlation with peak LH. The other independent predictive factor of irisin levels was BMI-SDS.

CONCLUSIONS

The mean irisin levels were higher in patients with CPP compared with other groups. The results of this study imply that increased irisin levels may be used as a marker of CPP provided that these findings are confirmed in larger prospective studies.

Dietary Thiols: A Potential Supporting Strategy against Oxidative Stress in Heart Failure and Muscular Damage during Sports Activity

Moderate exercise combined with proper nutrition are considered protective factors against cardiovascular disease and musculoskeletal disorders. However, physical activity is known not only to have positive effects. In fact, the achievement of a good performance requires a very high oxygen consumption, which leads to the formation of oxygen free radicals, responsible for premature cell aging and diseases such as heart failure and muscle injury. In this scenario, a primary role is played by antioxidants, in particular by natural antioxidants that can be taken through the diet. Natural antioxidants are molecules capable of counteracting oxygen free radicals without causing cellular cytotoxicity. In recent years, therefore, research has conducted numerous studies on the identification of natural micronutrients, in order to prevent or mitigate oxidative stress induced by physical activity by helping to support conventional drug therapies against heart failure and muscle damage. The aim of this review is to have an overview of how controlled physical activity and a diet rich in antioxidants can represent a "natural cure" to prevent imbalances caused by free oxygen radicals in diseases such as heart failure and muscle damage. In particular, we will focus on sulfur-containing compounds that have the ability to protect the body from oxidative stress. We will mainly focus on six natural antioxidants: glutathione, taurine, lipoic acid, sulforaphane, garlic and methylsulfonylmethane.

Implications of the Adiponectin System in Non-Small Cell Lung Cancer Patients: A Case-Control Study

Alterations of adipose tissue occurring in obesity have been recognized as a major risk factor for several cancers. The relationship between adipose tissue and lung cancer, which is the main cancer-related cause of death worldwide, still requires investigation. Perturbations in the adipokine system are likely to interfere with inter-organ crosstalk in lung cancer, which may influence the lung tumor microenvironment. Adiponectin (Acrp30) expression is deregulated in several cancer types. Acrp30 circulates as oligomers with a Low (LMW), Medium (MMW), and High Molecular Weight (HMW), with the latter mediating the main biological effects. Acrp30 acts through AdipoR1 and AdipoR2 receptors. T-cadherin has been described as a non-signaling receptor. This study's aim was to investigate the regulation of serum Acrp30 and its receptors in sample tissue from non-small cell lung cancer (NSCLC) patients. We recruited 72 NSCLC patients and 60 healthy controls, whom we evaluated in terms of their Acpr30 levels and oligomeric profile. In addition, the expression of AdipoRs in tissues from lung cancer specimens was also measured and compared to coupled healthy lung samples. Our findings show a significant reduction of total Acrp30 levels in NSCLC patients compared to normal subjects, with a specific down-regulation of HMW oligomers. Acrp30 expression was lower in lung adenocarcinoma than other subtypes, regardless of other factors. A significantly higher expression of AdipoR1 was observed, while no differences in R2 and a lower expression of T-cadherin were found in lung cancer specimens compared to normal healthy lung tissues. Involvement of the Acrp30 system in lung cancer may provide new insight into the interaction between adipose tissue and lung and sheds light on its potential ability to influence the lung tumor microenvironment.

Association of Total and High Molecular Weight Adiponectin with Components of Metabolic Syndrome in Mexican Children

OBJECTIVE

Childhood obesity linked to metabolic alterations, tend to appear simultaneously with altered adipocytokines, suggesting a role in pathogenetic development. Low circulating level of total and high molecular weight (HMW) adiponectin have been associated with components of the metabolic syndrome (MetS) and could represent an independent risk factor with potential use as a biomarker. To examine the prevalence of MetS in Mexican school children and to investigate the association of total and HMW adiponectin levels with biochemical parameters related to MetS.

METHODS

The study included a population of boys and girls, from 8 to 11 years old. Anthropometric and biochemical parameters were evaluated according to weight and MetS status. A correlation analysis was fitted to establish an association between adiponectin concentrations and metabolic indicators.

RESULTS

One-hundred and fifty five children participated (59.4% females) from 8-11 years of age. The prevalence of MetS was of 10.3%. Impaired biochemical parameters, including total and HMW adiponectin, were associated with obesity. The adiponectin level was significantly lower in MetS than in non-MetS subjects (4.5 vs. 5.4 μg/mL). Total- but not HMW adiponectin concentration was negatively correlated with blood pressure, fasting insulin, fasting blood sugar and Homeostatic Model Assessment for Insulin Resistance.

CONCLUSION

In young children, the total adiponectin level is associated with impaired biochemical parameters of carbohydrate metabolism and could be an excellent early predictor of metabolic complications.

Short-Term Physiological Effects of a Very Low-Calorie Ketogenic Diet: Effects on Adiponectin Levels and Inflammatory States

Adipose tissue is a multifunctional organ involved in many physiological and metabolic processes through the production of adipokines and, in particular, adiponectin. Caloric restriction is one of the most important strategies against obesity today. The very low-calorie ketogenic diet (VLCKD) represents a type of caloric restriction with very or extremely low daily food energy consumption. This study aimed to investigate the physiological effects of a VLCKD on anthropometric and biochemical parameters such as adiponectin levels, as well as analyzing oligomeric profiles and cytokine serum levels in obese subjects before and after a VLCKD. Twenty obese subjects were enrolled. At baseline and after eight weeks of intervention, anthropometric and biochemical parameters, such as adiponectin levels, were recorded. Our findings showed a significant change in the anthropometric and biochemical parameters of these obese subjects before and after a VLCKD. We found a negative correlation between adiponectin and lipid profile, visceral adipose tissue (VAT), C-reactive protein (CRP), and pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), which confirmed the important involvement of adiponectin in metabolic and inflammatory diseases. We demonstrated the beneficial short-term effects of a VLCKD not only in the treatment of obesity but also in the establishment of obesity-correlated diseases.

Circulating Irisin and esRAGE as Early Biomarkers of Decline of Metabolic Health

A decline in metabolic health may take place before observing any alteration in the levels of the traditional metabolic markers. New indicators of metabolic derangement are therefore compelling. Irisin is a myokine with important metabolic functions. The role of irisin as a metabolic biomarker in humans has not been fully established yet. We quantified plasma irisin and esRAGE in 106 apparently healthy individuals and we performed a cluster analysis to evaluate their associations with metabolic profile. Plasma levels of various traditional markers of metabolic risk (i.e., glucose and lipid levels) were all within the ranges of normality. We identified two clusters of individuals. Compared to cluster 2, individuals in cluster 1 had higher irisin levels, a metabolic profile shifted toward the limits of the reference ranges and lower esRAGE levels. The traditional metabolic blood tests seem not to be enough to identify a metabolic decline early. Irisin increase and esRAGE decrease may reflect a metabolic derangement at the beginning of its development. The role of these molecules as early biomarkers of decline of metabolic health seems an interesting topic to be further explored.

[Level of circulating Alarin in obese children and its association with insulin resistance]

OBJECTIVE

To study the level of circulating Alarin in obese children and its association with various metabolic parameters.

METHODS

A total of 86 obese children with a body mass index (BMI) above the 95th percentile were enrolled as the obesity group, and 82 healthy children, matched for age and sex, with a BMI below the 85th percentile were enrolled as the healthy control group. According to the presence or absence of insulin resistance (IR), the obesity group was further divided into an IR group with 27 children and a non-IR group with 59 children. Related anthropometric parameters, including body height, body weight, systolic blood pressure (SBP), and diastolic blood pressure (DBP), were measured, and BMI was calculated. Total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), uric acid (UA), fasting insulin (FINS), and fasting blood glucose (FBG) were measured. The area under the receiver operating characteristic curve (AUC) for glucose and insulin, Homeostasis Model Assessment of Insulin Resistance (HOMA-IR), and whole-body insulin sensitivity index (WBISI) were calculated. ELISA was used to measure the level of circulating Alarin.

RESULTS

The obesity group had a significantly higher level of circulating Alarin than the healthy control group (P<0.01). The IR group had a significantly higher level of circulating Alarin than the non-IR group (P<0.01). Circulating Alarin was positively correlated with BMI, TG, FBG, AUC-glucose, AUC-FINS, and HOMA-IR (P<0.05) and was negatively correlated with WBISI (P<0.05). The circulating Alarin level had a linear regression relationship with BMI, FBG, and HOMA-IR, among which HOMA-IR had the greatest influence on the circulating Alarin level (P<0.05).

CONCLUSIONS

There is a significant increase in the circulating Alarin level in obese children, which may be associated with the development of obesity and IR.

Decreased Blood Asprosin in Hyperglycemic Menopausal Women as a Result of Whole-Body Cryotherapy Regardless of Metabolic Syndrome

Endocrine dysfunction often occurs in metabolic syndrome (MetS), resulting in hyperglycemia and atherogenic blood lipid profile disorders. Asprosin is a newly discovered glucose-regulating hormone. The study aim was to determine whether the application of whole-body cryotherapy (WBC) affects asprosin and selected adipocytokines as well as insulin resistance in menopausal women with metabolic disorders. A total of 37 menopausal women were exposed to 20 WBC (-130 °C, 3 min). Blood glucose, asprosin, irisin, leptin, adiponectin, and insulin were measured before and after 20 WBC treatments, after which a homeostasis model assessment of insulin resistance (HOMA-IR) and atherogenic index of plasma (AIP) were calculated. The results were analyzed in the MetS group compared to the controls (CON) without MetS, and in the hyperglycemic (HG) group compared to the normoglycemic group (NG). After 20 WBC, a significant reduction (p < 0.05) in asprosin concentration was found in the MetS, HG, and CON groups, and a significant decrease (p < 0.05) in glucose concentration was noted in the HG group. Changes in asprosin concentration positively correlated with changes in glucose concentration. Asprosin concentration before WBC correlated positively with metabolic disorder risk factor levels, and the change in asprosin concentration after 20 WBC correlated negatively with metabolic disorder risk factor levels: fasting glucose, AIP, and the leptin/adiponectin index. Research indicates the possibility of using WBC in supporting metabolic disorders, type 2 diabetes (T2DM), and insulin resistance.

Circulating CTRP6 Levels are Increased in Overweight or Obese Chinese Individuals and Associated with Insulin Resistance Parameters: A Pilot Study

AIMS

CTRP6, a newly discovered adipokine, has been found to be a regulator for energy homeostasis. However, the association between circulating CTRP6 and obesity in humans is still unclear.

METHODS

256 individuals, including 185 overweight/obese (OW/OB) and 71 normal weight adults, were recruited for this study. Circulating concentrations of CTRP6 and adiponectin (Adipoq) were examined by ELISA.

RESULTS

Serum CTRP6 levels in obese individuals were significantly increased compared with those in healthy individuals (506.1±134.9 vs.363.3±80.5 ng/mL, P<0.01). Conversely, serum Adipoq concentrations in OW/OB individuals were markedly decreased compared with healthy controls [20.8 (12.1-29.3) vs. 14.1 ⁽ 8.61-17.7) ^; P<0.01]. Correlation analysis revealed that there was a positive relationship between circulating CTRP6 and age, BMI, Fat%, LDL-C, TG, WHR, TC, FBG, FIns, HOMA-IR and HbA1c, but there was an inverse correlation with Adipoq and HDL-C. Logistic regression analysis revealed that high serum CTRP6 levels are markedly associated with OW/OB. Finally, ROC curve analysis showed that the cut-off value for serum CTRP6 for prediction of IR is 518 ng/mL.

CONCLUSIONS

CTRP6 may be a marker related to OW/OB.

Adiponectin and Cardiovascular Risk. From Pathophysiology to Clinic: Focus on Children and Adolescents

Adiponectin (Ad) is a cytokine produced by adipocytes that acts on specific receptors of several tissues through autocrine, paracrine, and endocrine signaling mechanisms. Ad is involved in the regulation of cell survival, cell growth, and apoptosis. Furthermore, Ad plays an important pathophysiological role in metabolic activities by acting on peripheral tissues involved in glucose and lipid metabolism such as skeletal muscle, and the liver. Adiponectin has anti-inflammatory, anti-atherogenic, and insulin-sensitizing effects. For this reason, low levels of Ad are associated with the development of cardiovascular complications of obesity in adulthood. Numerous studies have shown that, even in children and adolescents, Ad is associated with risk factors for cardiovascular diseases. In obese children, reduced levels of Ad have been reported and Ad plasma levels are inversely related with abdominal obesity. Moreover, lower Ad concentrations are associated with the development of metabolic syndrome, insulin resistance and hypertension in pediatric subjects. In addition to a higher prevalence of cardiovascular risk factors, plasma values of Ad are also inversely associated with early organ damage, such as an increase in carotid intima-media thickness. It has been suggested that low Ad levels in childhood might predict the development of atherosclerosis in adulthood, suggesting the possibility of using Ad to stratify cardiovascular risk in obese children. Some evidence suggests that lifestyle modification may increase Ad plasma levels. The aim of this review is to summarize the evidence on the relationship between Ad, obesity, metabolic alterations and hypertension in children and adolescents, and to address the possibility that Ad represents an early marker of cardiovascular risk in pediatric subjects. Furthermore, the effects of non-pharmacological treatment (weight loss and physical activity) on Ad levels are considered.

Relationship between circulating irisin levels and overweight/obesity: A meta-analysis

BACKGROUND

Currently, the findings about irisin as a novel myokine related to obesity are inconsistent in overweight/obese people. To our knowledge, no systematic analysis has been conducted to evaluate the relationship between irisin levels and overweight/obesity.

AIM

To evaluate the association between circulating irisin levels and overweight/obesity.

METHODS

The Cochrane Library, MEDLINE, SCOPUS, and the ISI Web of Science were searched to retrieve all of the studies associated with circulating irisin levels and overweight/obesity. Standard mean difference values and 95% confidence intervals (CI) were estimated and pooled using meta-analysis methodology.

RESULTS

A total of 18 studies were included in our meta-analysis containing 1005 cases and 1242 controls. Our analysis showed that the circulating irisin level in overweight/obese people was higher than that in overall healthy controls (random effects MD = 0.63; 95%CI: 0.22-1.05; P = 0.003). In the subgroup analysis by ethnicity, the irisin level was higher in overweight/obesity people than that in controls in Africa (random effects MD = 3.41; 95%CI: 1.23-5.59; P < 0.05) but not in European, Asian, or American populations. In addition, in a subgroup analysis by age, the results showed that obese children exhibited a higher irisin level than controls (random effects MD = 0.86; 95%CI: 0.28-1.43; P < 0.05).

CONCLUSION

This meta-analysis provides evidence that circulating irisin is higher in obese individuals compared to healthy controls and it is important to identify the relationship between circulating irisin levels and overweight/obesity in predicting overweight/obesity.

Association between Irisin, hs-CRP, and Metabolic Status in Children and Adolescents with Type 2 Diabetes Mellitus

Proinflammatory cytokines and the novel myokine irisin, a cleavage product of FNDC5, have been found to play a role in obesity and type 2 diabetes mellitus (T2DM). Irisin has been shown to increase browning of adipose tissue, thermogenesis, energy expenditure, and insulin sensitivity, yet its association with inflammatory markers is still limited. Circulating irisin has been found to be increased in obesity, while in adult subjects with T2DM decreased levels have been found. However, data establishing the association of circulating irisin in children and adolescents with T2DM has not been described in the literature. The objective of this study was to determine irisin plasma concentration and its association with metabolic and adiposity markers and with hs-CRP, a surrogate marker of inflammation used in clinical practice, in a pediatric population with T2DM. A cross-sample of 40 Mexican children and adolescents aged 7-17 were recruited, 20 diagnosed with T2DM and 20 healthy controls. Plasma irisin levels were found to be lower in the T2DM group compared with controls, which could be attributed to a reduced PGC-1α activity in muscle tissue with a consequent decrease in FNDC5 and irisin expression. Irisin concentration was found to be positively correlated with HDL-c, LDL-c, and total cholesterol, while negatively correlated with BMI, waist circumference, and triglycerides. However, after multiple regression analysis, only HDL-c correlation remained significant. hs-CRP was higher in the T2DM group and positively associated with adiposity markers, unfavorable lipid profile, insulin levels, and HOMA-IR, but no association with irisin was found. Given the favorable metabolic effects attributed to irisin, the low plasma levels found in children and adolescents with T2DM could exacerbate the inflammatory and metabolic imbalances and the intrinsic cardiovascular risk of this disease. We propose an "irisin-proinflammatory/anti-inflammatory axis" to explain the role of irisin as a metabolic regulator in obesity and T2DM.

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.

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.

Irisin: A Hope in Understanding and Managing Obesity and Metabolic Syndrome

White adipose tissue (WAT) is an endocrine organ highly integrated in homeostasis and capable of establishing ways of communicating and influencing multiple metabolic processes. Brown adipose tissue promotes energy expenditure by incorporating the uncoupling protein 1 (UCP1), also known as thermogenin, which decouples cellular respiration and heat production, in the mitochondrial membranes. Recent data suggest the presence of a thermogenic cell formation from white adipocytes (beige or brite cells) with a potential role in preventing obesity and metabolic syndrome. The formation of these cells is influenced by physical exertion that induces expression of PPARγ coactivator-1 (PGC1) and downstream membrane protein, fibronectin type III domain-containing protein 5 (FNDC5) in skeletal muscle. Irisin, a thermogenic adipomyokine produced by FNDC5 cleavage is involved in the browning of adipose tissue. While animal studies are congruent with regard to the relationship between physical exertion and irisin release, the results from human studies are less than clear. Therefore, this review focuses on recent advances in our understanding of muscle and adipose tissue thermogenesis. Further, it describes the molecular mechanisms by which irisin impacts exercise, glucose homeostasis and obesity. Finally, the review discusses current gaps and controversies related to irisin release, its mode of action and its future potential as a therapeutic tool in managing obesity and metabolic syndrome.

Acute Anaerobic Exercise Affects the Secretion of Asprosin, Irisin, and Other Cytokines - A Comparison Between Sexes

Objective: The new adipokine, which is asprosin, affects glucose release from the liver to the blood, and thus, influences exercise metabolism. This is the first study assessing whether single anaerobic exercise affects asprosin secretion in women and men.

Methods: 10 men and 10 women (aged 21.64 ± 1.22 and 22.64 ± 1.49, respectively) performed a single 20-s bicycle sprint. Blood samples were collected before exercise and in the 3′, 15′, 30′, and 60′ of recovery, and 24 h after competition.

Results: Only in women did asprosin (P = 0.001) (15′, 30′, 60′, and 24 h after exercise) and irisin (P < 0.001) (15′, 30′, and 60′) concentrations increase. Leptin, however, decreased (P = 0.001) at 3′, 15′, and 30′ in women. There was an increase in interleukin-6 (P < 0.001) at 3′, 15′, 30′, and 60′ of recovery in men, at 15′, 30′, 60′, and 24 h of recovery in women, along with a simultaneous decrease in interleukin-1β (P < 0.001) at 15′, 30′, and 60′ of recovery in men, and at 15′ and 30′ of recovery in women (r = -0.35, P < 0.001). There was a positive correlation between asprosin and adiponectin and a negative one between asprosin and leptin. The increase in irisin concentration at 30′ of recovery was positively correlated with the increase in asprosin concentration and percentage fat content, while being negatively correlated with total and lean body mass (LBM).

Conclusion: The single anaerobic effort induced an increase in asprosin and irisin secretion while reducing leptin secretion in women. Adipocytokine concentration changes are inter-related. Regardless of sex, anaerobic efforts induce anti-inflammatory effects.

Relationship of Circulating Irisin with Body Composition, Physical Activity, and Cardiovascular and Metabolic Disorders in the Pediatric Population

Exercise-induced irisin, a recently discovered myokine, has been linked to insulin resistance, obesity, and other diseases in adults; however, information in children is scarce and contradictory. We analyzed the limited evidence of irisin’s effects in children and adolescents, and its association with body composition, exercise training, cardiovascular risk factors, and metabolic diseases, as well as the results of dietetic interventions. Both positive and negative correlations between irisin concentrations and body mass index, fat mass, fat-free mass, and other anthropometric parameters were found. Likewise, contradictory evidence was shown associating irisin plasma levels with cardiovascular and metabolic parameters such as glucose, insulin resistance, and cholesterol and other lipid and fatty acid plasma levels in healthy children, as well as in those with obesity and the metabolic syndrome. Gender, puberty, and hormonal differences were also examined. Furthermore, important contradictory findings according to the type and duration of exercise and of dietetic interventions in healthy and unhealthy subjects were demonstrated. In addition, correlations between mother–infant relations and circulating irisin were also identified. This review discusses the potential role of irisin in health and disease in the pediatric population.

An update on the role of irisin in the regulation of endocrine and metabolic functions

Irisin is a novel myokine and adipokine that has gained much attention recently due to its mechanisms of action. Irisin is secreted following proteolytic cleavage of its precursor fibronectin type III domain containing 5 (FNDC5). Following its release, irisin exerts its major action by increasing the expression of mitochondrial uncoupling protein 1 (UCP 1), which facilitates the conversion of white adipose tissue (WAT) into beige adipose tissue. Irisin is distributed in various body tissues and several actions have been attributed to its presence in those tissues. It has been suggested that it plays a role in metabolic diseases, ageing, inflammation and neurogenesis. However, the circulating levels of irisin are modulated by several factors such as diet, obesity, exercise, pharmacological agents and different pathological conditions. In this review, we have discussed the mechanisms by which irisin influences the functions of different body systems and how external factors in turn affect the circulating level of irisin. In conclusion, modification of circulating irisin level may help in the management of a variety of endocrine and metabolic disorders.

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.

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.