Visceral fat tissue expansion and adipokine secretion associated with systemic inflammation in obese subjects

To evaluate the hypothesis that excess visceral fat tissue promotes systemic inflammation by secreting inflammatory adipokines into the portal circulation, adipokine arteriovenous concentration differences across visceral fat tissue were assessed by obtaining portal vein and radial artery blood samples during gastric bypass surgery in 25 extremely obese subjects. Mean plasma IL-6 concentration was approximately 50% higher and mean plasma leptin concentration approximately 20% lower in portal vein than in radial artery (P=0.007 and P=0.0002, respectively) in these obese subjects, portal vein IL-6 concentration being directly correlated with systemic C-reactive protein concentration (P=0.005), an acute phase reactant whose hepatic synthesis may be mediated by IL-6. Visceral fat tissue expansion thus appears to be an important site for IL-6 secretion and this may explain the potential mechanistic link between visceral fat tissue expansion and systemic inflammation in subjects with abdominal obesity.

Abstract