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 hypermetabolism. This study examined the relationship between plasma leptin concentration, leptin gene expression, weight loss and the acute-phase response in a group of surgical patients. Methods: Body composition, plasma leptin, interleukin (IL) 6, soluble tumour necrosis factor receptor (sTNF-R) 55, sTNF-R75 and C-reactive protein were analysed in a cohort of 28 patients undergoing elective surgery. Subcutaneous and omental leptin messenger RNA (mRNA) was analysed in a subgroup of 14 patients. Results: After adjustment for fat mass (FM), a significant partial correlation coefficient was found between plasma leptin and serum IL-6 concentration (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 subcutaneous fat. Accelerated weight loss in patients with cancer with an ongoing inflammatory response could be mediated in part by inappropriately high plasma levels of leptin.