P0219 IMMUNE PHENOTYPE AND SERUM LEPTIN IN CHILDREN WITH OBESITY-RELATED LIVER DISEASE.

Abstract

Introduction: Aim: to define the role of leptin and immunological parameters, such as serum immunoglobulins, T and B lymphocyte subpopulations (CD3+, CD4+, CD8+, CD19+) and NK cells in pathogenesis of obesity-related liver disease in childhood. Methods: Two groups of consecutive obese children were studied: the 1st with obesity-related liver disease, the 2nd with isolated obesity. Obesity was defined in presence of a BMI >95° percentile for age, according to CDC criteria. Obesity-related liver disease was diagnosed in presence of hypertransaminasemia, liver steatosis at ultrasound and absence of known causes of liver disease. All patients were tested for liver function tests. All patients underwent an ultrasound assessment of the liver, aimed at identifying presence and severity of liver steatosis. The two groups were compared for leptin serum levels, erythrocyte sedimentation rate, immunoglobulin serum levels, CD3+, CD4+, CD8+, CD19+ and NK in the peripheral blood. Leptin, T and B lymphocyte subpopulations and NK concentrations were tested as previously described (1). Statistical analysis was performed by Student’s t test, Chi-square test and Fisher’s exact test, when appropriate. Results: The 1st group was composed by 23 obese children (18 males; median age 9 years, range 5–14.5) with hypertransaminasemia (mean ALT value 98,8 ± 92,1 IU/L) and steatosis at ultrasound. The 2nd group was composed by 16 obese children (7 males; median age 10.1 years, range 5–15)without signs of liver disease. In both groups leptin serum levels were increased (mean value 28.3 ± 14.7 ng/ml; normal range 10–15 ng/ml) but without significant difference between the two groups. All children with obesity-related liver disease showed significantly higher NK cells in peripheral blood (475 ± 259 cell/mm3; normal range 212–318) than obese children without liver disease (285 ± 138 cell/mm3) (p<0.01). No significant difference between the two groups was found for CD3+, CD4+, CD8+ cells. The value of CD19+ was significantly higher (508 ± 233 cell/mm3; normal range 200–400) in the first than in the second group (344 ± 154 cell/mm3; normal range 200–400) (p<0.01). Conclusion: Although leptin serum levels in adults correlate with liver steatosis (2), in the present study no correlation between circulating leptin concentrations and liver involvement was found. Since children with obesity-related liver disease showed significantly higher levels of CD19+ and NK in peripheral blood, it may be hypothesized that these cells play a role in pathogenesis of obesity-related liver disease.