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Adipocytokines, body composition, and fitness in children
Dan Nemet1, Ping Wang, Tohru Funahashi
1Department of Pediatrics, Center for the Study of Health Effects of Exercise in Children, University of California, Irvine, California 92868, U.S.A.
Insights
Adipose-derived cytokines like adiponectin and TNF-alpha are linked to body composition and insulin in children. Obesity may impact these relationships, suggesting early-life dysregulation.
Area of Science:
- Pediatric Endocrinology
- Metabolic Syndrome Research
- Adipose Tissue Biology
Background:
- Adipocytokines (e.g., TNF-alpha, IL-6, adiponectin) influence glucose regulation and atherosclerosis in adults.
- The role of adipocytokines in relation to body composition, insulin sensitivity, and fitness in children is largely unexplored.
Purpose of the Study:
- To investigate the correlations between adipocytokines, body composition, fasting insulin, and cardiorespiratory fitness in healthy children.
- To explore potential early-life origins of metabolic dysregulation associated with obesity.
Main Methods:
- Fasting blood samples were collected from 30 healthy children (mean age 12.7 years).
- Body composition was assessed using dual-energy X-ray absorptiometry (DEXA).
- Peak oxygen uptake was measured via cycle ergometry to determine fitness levels.
Main Results:
- Adiponectin showed inverse correlations with BMI and fat mass, and a positive correlation with HDL cholesterol.
- Tumor necrosis factor-alpha (TNF-alpha) and IL-6 were positively correlated with BMI and fat mass.
- Adiponectin was inversely correlated with fasting insulin, while fitness (peak oxygen consumption) was paradoxically negatively correlated with adiponectin and positively with TNF-alpha.
Conclusions:
- Adipocytokine profiles in children correlate with fat mass, insulin sensitivity, and cardiovascular risk factors, mirroring adult findings.
- In obese children, increased fat mass may interfere with the beneficial effects of fitness on adipocytokine levels.
- These findings suggest that detrimental adipocytokine dysregulation linked to obesity may commence in early childhood.
Abstract:
Recent evidence suggests a role for adipose derived cytokines (adipocytokines) such as tumor necrosis factor-alpha (TNF-alpha), IL-6, and the recently discovered adiponectin in the mechanism of impaired glucose regulation and atherosclerosis in adults. However, the relationship between adipocytokines and body composition, fasting insulin, and fitness is virtually unknown children. Fasting blood sampling was performed in 30 healthy, predominately Hispanic- and Asian-American children (16 boys, mean age 12.7 +/- 0.1 y old) from a lower socioeconomic area in Los Angeles. Adiposity was measured by dual x-ray absorptiometry (DEXA); and peak oxygen uptake using cycle ergometry. Adiponectin (mean 10.8 +/- 0.8 micro g/mL) was inversely correlated with body mass index (BMI, as percentile by age) (r = -0.48, p = 0.011) and fat mass (r = -0.43, p = 0.03). In contrast, TNF-alpha and IL-6 were both positively correlated with BMI and fat mass. Adiponectin was inversely correlated with fasting insulin (r = -0.52, p = 0.006), but no correlations were found for insulin and either TNF-alpha or IL-6. Adiponectin was correlated with HDL (r = 0.448, p = 0.019). Paradoxically, peak oxygen consumption (an indicator of fitness) was negatively correlated with adiponectin levels (r = -0.471, p = 0.013) and positively correlated with TNF-alpha (r = 0.560, p = 0.002). In children, adipocytokines are correlated with fat mass, insulin sensitivity, and cardiovascular risk factors in a manner that is qualitatively similar to relationships recently observed in adults. In more obese children, the mass of fat tissue may attenuate potentially positive effects of fitness on circulating levels of adiponectin and TNF-alpha. The novel data on adiponectin suggest that deleterious dysregulation of adipocytokines associated with obesity may occur relatively early in life.