Ghrelin and leptin modulate immunity and liver function in overweight children

Background:  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.
Methods:  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.
Results:  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.
Conclusions:  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.