1 Molecular and Cellular Biochemistry 216: 1–7, 2001. © 2001 Kluwer Academic Publishers. Printed in the Netherlands. Regulation of inducible adhesion molecule expression in human endothelial cells by grape seed proanthocyanidin extract Chandan K. Sen 1 and Debasis Bagchi 2 1 Energy and Environment Technologies Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA, USA and Department of Physiology, University of Kuopio, Finland; 2 School of Pharmacy and Allied Health Professions, Creighton University, Omaha, NE, USA Received 28 March 2000; accepted 4 July 2000 Abstract Altered expression of cell adhesion molecule expression has been implicated in a variety of chronic inflammatory conditions. Regulation of adhesion molecule expression by specific redox sensitive mechanisms has been reported. Grape seed pro- anthocyanidins have been reported to have potent antioxidant properties. We evaluated the effects of grape seed proanthocyanidin extract (GSPE) on the expression of TNFα-induced ICAM-1 and VCAM-1 expression in primary human umbilical vein en- dothelial cells (HUVEC). GSPE at low concentrations (1–5 μg/ml), down-regulated TNF α-induced VCAM-1 expression but not ICAM-1 expression in HUVEC. Such regulation of inducible VCAM-1 by GSPE was also observed at the mRNA expres- sion level. A cell-cell co-culture assay was performed to verify whether the inhibitory effect of GSPE on the expression of VCAM-1 was also effective in down-regulating actual endothelial cell/leukocyte interaction. GSPE treatment significantly de- creased TNFα-induced adherence of T-cells to HUVEC. Although several studies have postulated NF- κB as the molecular site where redox active substances act to regulate agonist-induced ICAM-1 and VCAM-1 gene expression, inhibition of inducible VCAM-1 gene expression by GSPE was not through a NF- κB-dependent pathway as detected by a NF-κB reporter assay. The potent inhibitory effect of low concentrations of GSPE on agonist-induced VCAM-1 expression suggests therapeutic potential of this extract in inflammatory conditions and other pathologies involving altered expression of VCAM-1. (Mol Cell Biochem 216: 1–7, 2001) Key words: proanthocyanidins, adhesion molecules, endothelial cell, inflammation, reactive oxygen species, antioxidant Introduction Cell adhesion represents a process that is centrally important in immune function and inflammation [1]. Intercellular ad- hesion molecule-1 (ICAM-1, CD54) and vascular cell adhe- sion molecule-1 (VCAM-1, CD 106) expressed on endothelial cells are major cell surface inducible glycoproteins that con- tribute to the cell adhesion processes [1, 2]. The ligands for ICAM-1 and VCAM-1 on leukocyte are lymphocyte func- tion-associated antigen-1 (LFA-1, CD11a/CD18) and very late antigens-4 (VLA-4, CD49d/CD29), respectively. Several stimuli such as pro-inflammatory cytokines [3], phorbol 12- myristate 13-acetate (PMA) [4, 5], oxidants [6] and HIV-1- tat protein [7] are known to activate the expression and func- tion of cell adhesion molecules. Cell adhesion molecule expression and adhesive proper- ties of cells are greatly modified in several diseased conditions involving redox imbalances such as cancer, atherosclerosis, diabetes, chronic-inflammation and ischemia-reperfusion in- jury. Therapeutic agents that down-regulate inducible ICAM- 1 or VCAM-1 expression and block leukocyte-endothelial interactions have been shown to markedly regulate the pro- gression of inflammatory responses in a number of in vivo models [2]. Regulation of both ICAM-1 and VCAM-1 gene Address for offprints: K. Sen, 512 Heart and Lung Institute, The Ohio State University Medical Center, 473 West 12th Avenue, Columbus, OH 43210-1252, USA