Impaired ex Vivo leukotriene B4 production characterizes the metabolic syndrome and is improved after weight reduction

Context: Neutrophil ( polymorphonuclear neutrophil) production of leukotriene B-4 (LTB4) may be associated with alterations in immune and inflammatory function that characterize the metabolic syndrome (MetS).Objective: We investigated whether polymorphonuclear neutrophil production of LTB4 and its metabolites 20-hydroxy-LTB4 (20-OH-LTB4) and 20-carboxyl-LTB4 were altered in subjects with features of the MetS before and after weight reduction.Design, Setting, Patients, and Intervention: In a case-controlled comparison, men and postmenopausal women with features of the MetS were matched with controls. Subjects with MetS were then matched and randomly assigned to either a 12-wk weight reduction study followed by 4-wk weight stabilization or 16-wk weight maintenance.Main Outcome Measures: Measurements were performed at baseline and at the end of the 16-wk period. Stimulated neutrophil LTB4 and its metabolites were measured by HPLC.Results: In the case-controlled study, body mass index, waist circumference, blood pressure, fasting triglycerides, and glucose were all significantly increased in subjects with features of the MetS ( P < 0.05). Production of LTB4 and 20-OH-LTB4 was significantly lower compared with controls ( P < 0.005). The weight loss intervention resulted in a 4.6-kg reduction in body weight and 6.6-cm decrease in waist circumference relative to controls and a significant increase in LTB4 and 20-OH-LTB4.Conclusions: Subjects with features of the MetS have lower stimulated LTB4, which is not due to increased metabolism of LTB4. Weight reduction restored the production of neutrophil LTB4, suggesting that in addition to modifying cardiovascular risk, weight loss may also help with the management of perturbed inflammatory responses in overweight subjects.