Role of inflammatory monocytes in adolescent metabolic syndrome

Abstract

Metabolic syndrome (MetSyn) is a cluster of risk factors for cardiovascular disease and diabetes that affects 1 in 3 obese children. Inflammatory cytokines secreted from macrophages are thought to be partly responsible for the metabolic abnormalities associated with MetSyn. This study aimed to determine whether peripheral blood monocytes (macrophage precursors) from overweight individuals with MetSyn (Overwt-MetSyn) demonstrate enhanced activation of inflammatory signaling pathways when compared to metabolically normal overweight (Overwt-Healthy) or lean individuals. We conducted a cross sectional pilot study involving 24 adolescents (six boys and eighteen girls) recruited from the University of Massachusetts Boston and Worcester campuses. Six subjects were classified as Overwt-MetSyn using a modified definition proposed by the International Diabetes Federation. The Overwt-MetSyn group demonstrated an elevated expression of TLR2 and TLR4 in peripheral monocytes, and increased circulating levels of TNFa and IL6. Expression of TLR2 and TLR4 showed a positive correlation with circulating cytokines, and expression of TNFa correlated with waist circumference and BMI. Metabolic syndrome in adolescents is associated with increased activation of the TLR signaling pathway in monocytes. The knowledge gained from this study will advance our understanding of the contribution of monocytes to the pathophysiology of MetSyn.