Only C-Reactive Protein, but not TNF-α or IL6, Reflects the Improvement in Inflammation after Bariatric Surgery

Increased C-reactive protein (CRP) levels strongly predict inflammatory diseases such as obesity and tissue damage. We wanted to study the CRP in plasma and tissue in morbidly obese patients before and after surgery and relate it with the expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in tissues. We analyzed CRP concentration in plasma, adipose and liver, and the expression of IL-6 and TNF-α, in those tissues, in 34 morbidly obese patients before and 1, 6 and 12 months after gastric bypass. Morbidly obese had a greater amount of CRP in plasma (3 times) and tissues (21, 5 and 7 times more in liver, subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT), respectively) than control subjects. The expression of IL-6 in SAT showed a similar profile to plasma and SAT CRP in both obese patients and after weight loss, despite no significant correlation was found. We were only able to detect IL-6 in the liver of a subset of patients. The expression of TNF-α after surgery showed a no significant slight tendency to decrease in SAT with weight loss, but in the liver, we did not observe any change. IL-6 in SAT, but not in liver, seems to be more closely related to plasma and tissue CRP than TNF-α in both obese patients and after weight loss. Plasma CRP protein perfectly reflects the decrease in inflammation and improves with weight loss in the tissues.