Yoshinori Nishizawa

Gallates Inhibit Cytokine-Induced Nuclear Translocation of NF-κB and Expression of Leukocyte Adhesion Molecules in Vascular Endothelial Cells

Gallates (gallic acid esters) belong to the class of phenolic compounds, which are abundant in red wine. In this study, we show that gallates can inhibit cytokine-induced activation of nuclear factor kappaB (NF-kappaB) and thereby reduce expression of endothelial-leukocyte adhesion molecules in cultured human umbilical vein endothelial cells (HUVECs). Pretreatment of HUVECs with ethyl gallate (3 to 10 micromol/L) significantly suppressed interleukin-1alpha (IL-1alpha)- or tumor necrosis factor-alpha (TNF-alpha)- induced mRNA and cell-surface expression of vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1), and E-selectin, which was associated with reduced adhesion of leukocytes to HUVECs. Gel shift assays with the NF-kappaB consensus sequence showed the decreased densities of the shifted bands in gallate-treated HUVECs. Furthermore, gallate pretreatment inhibited cytokine-induced transcription of a fusion gene, which consisted of 4 repeats of the NF-kappaB consensus sequence and the luciferase reporter gene. Immunoblot analysis of nuclear extracts and whole-cell lysates demonstrated the decreased amounts of NF-kappaB p65 in nuclei but equal amounts of inhibitor-kappaBalpha (I-kappaBalpha) in whole-cell lysates of ethyl gallate-treated HUVECs. Incubation of the nuclear extracts from cytokine-activated HUVECs with ethyl gallate did not affect the NF-kappaB shifted bands induced by cytokines in gel shift assays. Taken together, these data demonstrate that ethyl gallate can inhibit cytokine-induced nuclear translocation of NF-kappaB p65 by way of a mechanism independent of I-kappaBalpha degradation and thereby suppress expression of VCAM-1, ICAM-1, and E-selectin, which was associated with reduced adhesion of leukocytes. These results in vitro demonstrate that gallates can exhibit anti-inflammatory properties by blocking activation of NF-kappaB and suggest that these natural compounds, abundant in red wine, may play important roles in the prevention of atherosclerosis and inflammatory responses in vivo.