Lycopene alleviates obesity-induced inflammation and insulin resistance. - GreenMedInfo Summary

SCOPE: Adipose tissue macrophage (ATM) recruitment and polarization are pivotal in the development of insulin resistance. However, treatment modalities targeting ATMs remain limited. We examined the effects of lycopene, an antioxidant carotenoid compound, on adipose tissue inflammation and insulin resistance in high fat (HF) diet-induced obese mice.

METHODS AND RESULTS: C57BL/6J mice were fed a HF diet or a HF diet containing lycopene (HF+LY) for 8 weeks. Lycopene attenuated HF diet-induced glucose intolerance and hyperinsulinemia. Compared with HF mice, HF+LY mice exhibited attenuated adipocyte hypertrophy and macrophage infiltration in epididymal white adipose tissue (eWAT) and hepatic steatosis and inflammation. Flow cytometry analysis of ATMs demonstrated that lycopene attenuated the increased number of ATMs in HF diet-fed mice. In addition, HF+LY mice had 23% fewer M1-polarized ATMs and 60% more M2-polarized ATMs than HF mice, resulting in the predominance of M2 over M1 in the ATM population. M2-dominant polarization was also seen in hepatic macrophages in HF+LY mice. Moreover, lycopene promoted IL-4-induced M2 polarization by increasing the phosphorylation levels of STAT6 and Akt in Raw 264.7 macrophages.

CONCLUSIONS: Lycopene facilitated M2-dominant polarization in ATM, thereby attenuating HF diet-induced inflammation and insulin resistance in eWAT and the liver. This article is protected by copyright. All rights reserved.