Effect of weight loss on neutrophil resolvins in the metabolic syndrome

Background: Non-resolving inflammation associates with obesity and insulin resistance, and may be dependent on the balance of inflammatory substances and specialised pro-resolving mediators of inflammation (SPM) that act to halt the inflammatory response. This controlled trial examined the effect of weight loss on neutrophil synthesis of SPM in volunteers with the metabolic syndrome (MetS). Methods: Volunteers with MetS (n = 42) were matched for age and gender and randomly assigned to a 12-wk weight loss program followed by 4-wk weight stabilization or a 16-wk weight maintenance program. At baseline and 16 weeks, isolated neutrophils were stimulated with calcium ionophore and the released SPM were measured by LC-MS/MS. Results: At baseline the SPM resolvin (Rv) E1, 18R-RvE3, RvD2 and Maresin-1 (MaR-1) were detected from stimulated neutrophils. The concentration of released RvE1 was at least 6-fold that of other detected SPM. Weight loss of 4.7 ± 0.8 kg, led to a 2-fold increase in RvE1, P = 0.013, relative to the weight maintenance group. The increase in RvE1 after weight loss was related to, but independent of leukotriene B_4. Conclusion: Following weight loss, human neutrophils from individuals with the metabolic syndrome are capable of releasing larger amounts of RvE1 upon stimulation.