Resveratrol inhibits inflammation induced by heat-killed Listeria monocytogenes

Resveratrol is a polyphenolic compound in red wine that has antioxidant and cardioprotective effects in animal models. Listeria monocytogenes is a pathogen that mainly affects immunocompromised individuals and is initially detected at the cell surface or in phagosomes by toll-like receptor 2. Many antioxidants also exert anti-inflammatory activities; therefore, we evaluated the anti-inflammatory properties of resveratrol by studying the various inflammatory responses induced by heat-killed L. monocytogenes (HKLM). Resveratrol strongly blocked HKLM-induced NADPH oxidase-1 mRNA and reactive oxygen species production by macrophages. Resveratrol also suppressed monocyte chemotactic protein-1 expression, cyclooxygenase-2 expression, prostaglandin production, inducible nitric oxide (NO) synthase expression, and NO production induced by HKLM. We investigated the signaling pathway involved in the resveratrol effect. HKLM stimulated glycogen synthase kinase 3β (GSK3β) and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. The involvement of GSK3β and ERK1/2 was tested using inhibitors. While the GSK3β inhibitor LiCl potentiated the effect of HKLM, the MEK inhibitor U0126 blocked these responses. Additionally, pretreatment with resveratrol blocked phosphorylation of both kinases induced by HKLM. These results suggest that HKLM is strong inducer of inflammatory mediators, and that the inhibitory effect of resveratrol may be mediated by the GSK3β and ERK1/2 pathways.