Expression of insulin-like growth factor I and its receptor in the liver of children with biopsy-proven NAFLD

BACKGROUND AND AIMS: Nonalcoholic fatty liver disease is one of the major complications of obesity, occurring already in pediatric age. Insulin like growth factor-I has been proposed as a potential therapeutic agent for its beneficial effect in experimental liver fibrosis. The aim of this work was to investigate the expression of insulin-like growth factor-I and its receptor in the liver of children with biopsy-proven nonalcoholic fatty liver disease and relate it to liver histological features. METHODS: 45 obese children and adolescents (14 females and 31 males) with nonalcoholic fatty liver disease were included. Insulin like growth factor-I and its receptor expression was evaluated in liver tissue by immunofluorescence and qPCR. RESULTS: The expression of insulin like growth factor-I and its receptor were significantly related to fibrosis and were higher in children with stage 3 fibrosis compared to stage 1 and 2 (p<0.001 and p = 0.007 respectively). mRNA of insulin like growth factor-I receptor was higher in more advanced stages of fibrosis (p<0.001). Furthermore, the expression of insulin like growth factor-I and its receptor in hepatic stellate cells, the cell type mostly involved in fibrosis progression, was significantly increased in stage 3 fibrosis compared to stage 1 (p = 0.01 and p = 0.008 respectively). CONCLUSIONS: We demonstrated for the first time that insulin like growth factor-I and its receptor are upregulated in children with nonalcoholic fatty liver disease. These findings give a new hint for the potential therapeutic use of insulin like growth factor-I in pediatric nonalcoholic fatty liver disease complicated by liver fibrosis.