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.

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.