Epigallocatechin gallate suppresses LPS endocytosis and nitric oxide production by reducing Rab5-caveolin-1 interaction.

Epigallocatechin gallate (EGCG) is the major polyphenol in green tea and the main bioactive compound responsible for the health benefits of tea consumption. The molecule exhibits antimicrobial and anti-inflammatory activities. However, little is known about the molecular mechanisms by which EGCG elicits those activities. In this study, we examined the effects of EGCG on lipopolysaccharide (LPS) endocytosis and LPS-induced NO production. We also investigated the mechanism with focus on the effect of EGCG on interaction between small GTPase Rab5 and caveolin-1. EGCG suppressed endocytosis of LPS and LPS-induced nitric oxide production in mouse macrophage-like cells (RAW 264). EGCG suppressed the Rab5-caveolin-1 interaction and reduced Rab5 activity. The results suggest that EGCG reduced LPS-induced innate immune responses through suppression of LPS endocytosis by interfering with Rab5-caveolin-1 interaction and by reducing Rab5 activity.