Increased plasma interleukin 6 concentrations and exaggerated adipose tissue interleukin 6 content in severely obese patients after operative trauma.

BACKGROUND: The cytokine response to operative trauma may be altered in obesity. Thus, we monitored changes in systemic and adipose tissue content of interleukin 6 (IL-6) and in insulin resistance in nonobese versus severely obese patients before and immediately after abdominal operations.
METHODS: At the beginning and the end of operation, blood samples and biopsies consisting of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were collected from 13 nonobese and 33 severely obese patients. Systemic concentrations of glucose, insulin, and IL-6, as well as adipose tissue content of IL-6, were determined.
RESULTS: Plasma IL-6 concentration and adipose tissue content of IL-6 increased, compared with baseline in patients after operation (plasma, 13- and 5.7-fold; VAT, 270- and 210-fold; SAT, 79- and 8.2-fold in severely obese vs nonobese patients, respectively). The increase in IL-6 in plasma and in both VAT and SAT was exaggerated in severely obese patients, compared with nonobese patients. Increases after operation in plasma IL-6 concentrations were correlated positively to the corresponding increases in both SAT and VAT IL-6 content (r = 0.57 and 0.66, respectively). Also, we found a positive correlation between the worsening of insulin resistance and increases in both plasma and SAT IL-6 concentrations (r = 0.40 and 0.51, respectively).
CONCLUSIONS: Circulating IL-6 concentrations both at baseline and after operation are related strongly to abdominal adipose tissue content of content of IL-6 and are exaggerated in severely obese persons. After operation, worsening of insulin resistance is associated with increasing plasma and adipose tissue content of IL-6.