Obesity is associated with insulin resistance. Insulin resistance and the presence of pro-inflammatory mediators are thought to cause a state of vascular endothelial dysfunction, an abnormal lipid profile, hypertension, and vascular inflammation. These chronic inflammatory responses, which are characterized by abnormal cytokine production, lead to activation of a pro-inflammatory signaling pathway. Leptin is an important mediator of inflammatory processes and immune-mediated diseases. The purpose of this study was to investigate the relationship between leptin and various cytokines associated with obesity in adolescents.

Sixty-six obese adolescents (between 16-17 years of age, obesity index >130%) and 26 normal controls were included in this study. Obesity index and body mass index (BMI) were calculated. Serum lipid profile, AST and ALT were tested after 10 hours of fasting. Tumor necrosis factor alpha (TNF-α) and Interleukin-6 (IL-6) levels were measured by ELISA. Insulin, adiponectin, and leptin levels were estimated by radioimmunoassay.

Leptin was significantly higher in the obese adolescents compared to the control adolescents (12.0±6.8 ng/mL vs 6.3±1.0 ng/mL). TNF-α, IL-6, and insulin were significantly higher in the obese adolescents. Adiponectin was significantly lower in the obese group than the control group (3.3±1.9 µg/mL vs 5.0±1.4 µg/mL). Leptin had positive correlations with obesity index, BMI, and IL-6.

In obese adolescents, leptin, TNF-α, IL-6, and insulin might be important mediators of obesity. Further clinical research is necessary to ascertain leptin as a predictor of cardiovascular diseases and to develop a guideline for clinical intervention.