Increased serum amyloid A concentrations in morbid obesity decrease after gastric bypass.

Background: Obesity is considered a state of low-grade chronic inflammation, which may favor the development of cardiovascular diseases. Serum amyloid A (SAA) is an acute phase protein synthesized in response to infection, inflammation, injury, and stress. The aim of the present study was to compare the circulating concentrations of SAA and the mRNA expression in omental adipose tissue between lean and obese individuals and to analyze the effect of weight loss after gastric bypass.

Methods: 16 lean volunteers (BMI 20.5 +/- 0.6 kg/m2) and 24 obese patients (BMI 47.0 +/- 1.2 kg/m2) were included in the study. Serum concentrations of SAA were measured by ELISA. In addition, the concentrations of SAA in 18 morbidly obese patients (7 male/11 female; BMI 44.6 +/- 1.9 kg/m2) were measured before and after weight loss following Roux-en-Y gastric bypass (RYGBP). SAA expression in omental adipose tissue was quantified by RT-PCR in biopsies from obese patients undergoing RYGBP and from age-matched lean individuals subjected to Nissen fundoplication.

Results: Obese patients exhibited significantly increased circulating SAA concentrations (6.6 +/- 0.5 vs 39.3 +/- 9.1 microg/ml; P<0.01) compared to lean subjects. A significant positive correlation was found between logSAA and body fat (r=0.631, P<0.0001). Obese patients showed significantly increased (P<0.05) mRNA expression of SAA in omental adipose tissue compared to lean subjects. Weight loss significantly decreased SAA concentrations after RYGBP (final BMI 28.5 +/- 0.9 kg/m2, P<0.0001 vs initial) from 47.5 +/- 14.5 to 15.7 +/- 2.9 microg/ml (P<0.05).

Conclusion: It can be concluded that serum SAA and mRNA expression of SAA in omental adipose tissue are increased in obese patients contributing to the obesity-associated cardiovascular disease risk. Moreover, weight loss reduces SAA concentrations, which may contribute to the beneficial effects accompanying weight reduction.