Leptin and its relation to weight loss, ob gene expression and the acute-phase response in surgical patients

Background: Patients with cachexia suffer from anorexia, weight loss and hy permetabolism. This study examined the relationship between plasma leptin c oncentration, leptin gene expression, weight loss and the acute-phase respo nse in a group of surgical patients. Methods: Body composition, plasma leptin, interleukin (IL) 6, soluble tumou r necrosis factor receptor (sTNF-R) 55, sTNF-R75 and C-reactive protein wer e analysed in a cohort of 28 patients undergoing elective surgery. Subcutan eous and omental leptin messenger RNA (mRNA) was analysed in a subgroup of 14 patients. Results: After adjustment for fat mass (FM), a significant partial correlat ion coefficient was found between plasma leptin and serum IL-6 concentratio n (P = 0.037). A positive correlation was found only between plasma leptin and omental leptin mRNA (P = 0.009). Patients with an acute-phase response had a significantly higher level of plasma leptin per unit FM (P = 0.049). Stepwise multiple regression showed that FM (P < 0.0005) and serum IL-6 (P = 0.018) were independent predictors of plasma leptin level. Conclusion: Plasma leptin levels appear to be influenced by proinflammatory cytokines. Omental fat may have more influence on plasma leptin than subcu taneous fat. Accelerated weight loss in patients with cancer with an ongoin g inflammatory response could be mediated in part by inappropriately high p lasma levels of leptin.