Body mass index and the visceral adipose tissue expression of IL-6 and TNF-alpha are associated with the morphological severity of non-alcoholic fatty liver disease in individuals with class III obesity

Summary Objectives To analyze the mRNA expression of interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α) in the liver and white adipose tissue samples of individuals with class III obesity (body mass index ≥40.0 kg/m 2 ) with non-alcoholic fatty liver disease (NAFLD). Methods This cross-sectional study included patients with class III obesity exhibiting early or late morphological presentation of NAFLD (non-alcoholic hepatic steatosis [NAFL], n  = 8 and non-alcoholic steatohepatitis [NASH], n  = 13, respectively). All patients underwent bariatric surgery and peripheral blood, liver, and visceral white adipose tissue (WAT) samples were collected. Socio-demographic, anthropometric, clinical, plasma biochemical, and nutritional characteristics of each study subject were assessed and compared between patients presenting with NAFL and NASH. IL-6 and TNF-α mRNA expression in the liver and WAT samples were measured by using quantitative real time-polymerase chain reaction (qRT-PCR). Results Individuals with class III obesity and NASH showed higher body mass index (BMI) and higher IL-6 and TNF-α mRNA expression in the WAT compared to that of patients with NAFL ( p  = 0.01, for all associations). Conclusions Individuals with class III obesity with higher morphological severity of NAFLD exhibited higher BMI and higher IL-6 and TNF-α expression in the WAT. Future prospective studies are warranted to determine how BMI, IL-6, and TNF-α affect the progression of NAFLD in individuals with class III obesity.