Ghrelin and leptin modulate immunity and liver function in overweight children

Abstract

The rising prevalence of obesity represents a growing worldwide public health problem. Interactions of adipocytokines and low-grade systemic inflammation presently are considered important in the development of obesity, as well as associated chronic disease including bronchial asthma, obesity-related liver disease and type 2 diabetes mellitus. The purpose of the present study was to investigate metabolic, hormonal, immunologic and inflammatory factors in overweight children and to further clarify possible immunomodulatory effects of obesity-related hormones and cytokines. Forty-nine prepubertal overweight children and 49 age-matched controls of normal weight without underlying disease were enrolled. Levels of plasma ghrelin and serum leptin, cytokines (interleukin [IL]-4, IL-10, IL-12, 1L-13), C-reactive protein, immunoglobulin, and insulin were measured, and liver function tests were done to better understand their status in the setting of obesity. Overweight subjects had significantly higher measures of adiposity (body mass indexI, % body fat) and had significantly higher serum levels of IgG, IgA and IgE than non-obese children (P = 0.038, 0.0043, 0.0034, respectively); the opposite was true for IgM (P = 0.025). The incidence of presumed non-alcoholic fatty liver disease was 28.6% in overweight children. In overweight children, serum leptin levels were associated with liver function index (aspartate aminotransferase/alanine aminotransferase ratio) and serum insulin levels. Some elevated immunoglobulin levels significantly correlated with plasma ghrelin levels and liver function index. It is possible that appetite-regulating hormones modulate both humoral immunity and liver function. Further studies with a larger number of subjects are needed to clarify the precise mechanisms of this association.