The Inhibitory Effect of Quercetin on Adipose Tissue Inflammation in Mice Fed on a High-fat Diet

Background: Obesity-induced adipose inflammation contributes to the development of metabolic disorders such as insulin resistance and type 2 diabetes. In this study, we investigated whether quercetin, a naturally occurring phytochemical, can attenuate adipose tissue inflammation in obese mice. Methods: Male C57BL/6 mice were randomly assigned into either control (RD, N=6), high fat diet (HFD, N=6), or HFD supplemented with 0.05% quercetin (HFD+Que, N=6) groups and treated with their respective diets for 9 weeks. The inflammatory cytokine pro-teins were measured by ELISA, and macrophage populations were determined by immunohistochemistry. The inflammatory receptors and downstream signaling molecules were measured by qPCR and western blot, respectively. Results: We show here that in an HFD-fed mice model, quercetin supplementation reduced adipose tissue weight without affecting HFD-induced body weight gain. Quercetin supplementation reduced expression of inflammatory cytokines (TNF-α, MCP-1, MIP-1α) and macrophage accumulation (F4/80) in adipose tissue of an HFD-fed mice. Quercetin also suppressed the expression of inflammatory receptors (CCR2, TLR4, TNFRSF9) and the activation of downstream inflammatory signaling molecules (JNK, NF-κB) in adipose tissue. Conclusion: These findings indicate that quercetin can reduce adipose inflammatory responses in mice exposed to HFD by inhibiting inflammatory cytokines production, inflammatory receptor expression and their signaling pathway. Quercetin may be useful for preventing HFD-induced adipose tissue inflammation.