Quercetin ameliorates LPS-induced inflammation in human peripheral blood mononuclear cells by inhibition of the TLR2-NF-κB pathway

Quercetin, a dietary flavonoid abundant in fruits, vegetables, and herbs, presents various pharmacological effects. This study aimed to investigate the anti-inflammatory effect and the underlying mechanism of quercetin in lipopolysaccharide (LPS)-stimulated human peripheral blood mononuclear cells (PBMCs). Cell viability was measured by the Cell Counting Kit-8 assay. The mRNA expression of Toll-like receptor 2 (TLR2) was assessed by quantitative real-time polymerase chain reaction. Inflammatory cytokine secretions and nuclear factor (NF)-kappa B levels were analyzed by enzyme-linked immunosorbent assay. Our findings showed that quercetin significantly reduced LPS-induced cytotoxicity in human PBMCs. Quercetin suppressed the secretion of tumor necrosis factor-alpha, interleukin (IL)-1 beta, and IL-6 in LPS-stimulated human PBMCs. Moreover, quercetin reduced the LPS-induced increase in the expression of TLR2 mRNA and decreased the NF-kappa B concentration in LPS-stimulated human PBMCs. The data indicates that quercetin plays an important role in LPS-induced inflammation in human PBMCs via suppression of the TLR2-NF-kappa B pathway.