The procyanidin trimer C1 inhibits LPS-induced MAPK and NF-κB signaling through TLR4 in macrophages

Natural products and dietary components rich in polyphenols have been shown to reduce inflammation; however, the molecular mechanisms underlying this anti-inflammatory activity are not completely characterized, and many features remain to be elucidated. This research was carried out to clarify the potential role of procyanidin trimer Cl in the anti-inflammatory effect of polyphenols. Procyanidin C1 inhibited inducible nitric oxide synthase-mediated nitric oxide production and the release of pro-inflammatory cytokines (interleukin-6 and tumor necrosis factor-alpha) in lipopolysaccharide (LPS)-induced macrophages. Treatment with procyanidin Cl resulted in a significant decrease in prostaglandin E-2 and cyclooxygenase-2 levels, as well as the expression of cell surface molecules (CD80, CD86, and MHC class II), which was induced by LPS. Furthermore, our data demonstrated that the anti-inflammatory effect of procyanidin Cl occurs through inhibition of mitogen-activated protein kinase (p38 and c-Jun N-terminal kinase) and nuclear factor-kappa B signaling pathways. These 2 factors play a major role in controlling inflammation, through toll-like receptor 4, suggesting that procyanidin Cl plays a potent role in promoting anti-inflammatory activity in macrophages. These results represent a novel and effective therapeutic intervention for the treatment of inflammatory disease. (C) 2012 Elsevier B.V. All rights reserved.