Circulating levels of interleukin-18 in patients with non-alcoholic fatty liver disease

Background and aims. Non-alcoholic fatty liver disease (NAFLD) is strongly associated with obesity and diabetes mellitus. IL-18 is associated with obesity and metabolic syndrome. Our aim was to investigate the relationship of IL-18 with adiponectin and liver histology in subjects with NAFLD who had no additional disorder such as morbid obesity, diabetes mellitus and hypertension. Methods. Plasma levels of IL-18 and adiponectin were measured by ELISA in 96 male subjects with NAFLD [n=65 for non-alcoholic steatohepatitis (NASH) and n=31 for simple steatosis (SS)]. Results. IL-18 levels were not different between the two groups (p=0.89). There was no significant association of IL-18 with adiponectin, insulin resistance and histopathological findings. Adiponectin was lower in the NASH group compared to the SS group (p=0.02) and it was found to be negatively correlated with hepatic steatosis and fibrosis (r=-0.442, p < 0.001 and r=-0.292, p=0.02, respectively). Conclusions. This study indicates that circulating IL-18 levels are not altered in male subjects with NAFLD. These results suggest that in the absence of metabolic risk factors, IL-18 per se may not be involved in the pathogenesis of NASH and SS.