Inhibition of homodimerization of toll-like receptor 4 by 6-shogaol.

Abstract

Toll-like receptors (TLRs) play a critical role in sensing microbial components and inducing innate immune and inflammatory responses by recognizing invading microbial pathogens. Lipopolysaccharide-induced dimerization of TLR4 is required for the activation of downstream signaling pathways including nuclear factor-kappa B (NF-kappaB). Therefore, TLR4 dimerization may be an early regulatory event in activating ligand-induced signaling pathways and induction of subsequent immune responses. Here, we report biochemical evidence that 6-shogaol, the most bioactive component of ginger, inhibits lipopolysaccharide-induced dimerization of TLR4 resulting in the inhibition of NF-kappaB activation and the expression of cyclooxygenase-2. Furthermore, we demonstrate that 6-shogaol can directly inhibit TLR-mediated signaling pathways at the receptor level. These results suggest that 6-shogaol can modulate TLR-mediated inflammatory responses, which may influence the risk of chronic inflammatory diseases.