Inflammatory cytokines and non-alcoholic fatty liver disease (NAFLD) in obese children and adolescents

Non-alcoholic fatty liver disease is characterized by the intrahepatic deposition of fat. It is the most prevalent liver disease in the world, affecting obese children and adolescents. Its pathophysiology is not fully understood, although it is often related to insulin resistance. This in turn would be due to an inflammatory condition common to obesity. Thus, the objective of this study was to describe the behavior of proinflammatory cytokines in obese children and adolescents, with and without non-alcoholic fatty liver disease. A fasting venous blood sample was obtained of consecutive 90 obese individuals aged 8-18 years, of both sexes, for laboratory determinations of glycaemia, basal insulin and homeostasis model assessment insulin-resistance index, and the inflammatory markers tumor necrosis factor-alpha (TNF-α), interleukins 2 and 6 (IL-2 and IL-6), interferon-gamma and high sensitive C-reactive protein. The clinical evaluation included weight, height and waist circumference. We used the body mass index/age indicator for the severity of overweight assessment. The degrees of steatosis were determined by ultrasonography. Quantitative and qualitative variables were respectively expressed by measures of central tendency/dispersion and simple/relative frequency, using Statistical Program for Social Sciences, version 20.0. A p-value < 0.05 was considered as significant. A total of 90 individuals were studied, with a mean age of 11.98 (2.72) years, of which 48 (53%) were male. The body mass index (BMI) for age (BMI/i) and sex (z-score) classified 38 (42.2%) participants as obese and 52 (57.7%) as severe obese; Hepatic steatosis was identified in 56 (62.2%) participants and approximately 90% of them presented grade I steatosis. The inflammatory markers TNF-α, and C-reactive protein were increased in the studied sample and correlated in a positive and statistically significant way with the index of body mass/age and sex. Hepatic steatosis was prevalent in the group of children and adolescents studied, but was not related to obesity degrees.