Epigallocatechin-3-O-gallate inhibits the angiotensin II-induced adhesion molecule expression in human umbilical vein endothelial cell via inhibition of MAPK pathways.

Epigallocatechin-3-O-gallate (EGCG) is the main catechin, which is derived from Camellia sinensis plant. Vascular cell adhesion molecules (VCAMs) and intercellular adhesion molecules (ICAMs) mediate the binding of inflammatory cells onto the vascular wall-promoting the early phase of atherosclerosis. In the present study, we investigated the mechanism(s) by which EGCG inhibits angiotensin II (Ang II)-induced elevation of the membrane associated VCAM-1 and ICAM-1 in human umbilical vein endothelial cells (HUVEC). Ang II induced a 40% increase of VCAM-1 and ICAM-1 in the plasma membrane. EGCG (10 to 50 microM) inhibited the effect of Ang II in a concentration-dependent manner. In parallel, the Ang II-induced elevation of the mRNA expressions of VCAM-1 and ICAM-1 in HUVEC were completely inhibited by 50 microM EGCG. Since mitogen-activated protein kinase (MAPK) families are involved in vascular inflammation in response to stressful stimuli, we investigated the effects of EGCG on the MAPK signal transduction pathway stimulated by Ang II. EGCG (30 to 50 microM) completely inhibited the Ang II-induced phosphorylation of ERK (extracellular signal-regulated kinase) 1/2 and p38 MAPK. PD98059, an inhibitor of ERK1/2 inhibited the Ang II-induced increase of VCAM-1 but not of ICAM-1 in the plasma membranes. In contrast, SB203580, an inhibitor of p38 MAPK inhibited both the Ang II-induced enrichment of ICAM-1 and VCAM-1. From these results, it may be concluded that EGCG inhibits the Ang II-induced elevation of VCAM-1 and ICAM-1 in the HUVEC plasma membranes via inhibition of the p38 MAPK and the ERK1/2 signalling pathways resulting in an inhibition of the VCAM-1 and ICAM-1 transcription.