EMODIN (3-METHYL-1,6,8-TRIHYDROXYANTHRAQUINONE) INHIBITS TNF-INDUCED NF-KAPPA-B ACTIVATION, I-KAPPA-B DEGRADATION, AND EXPRESSION OF CELL-SURFACE ADHESION PROTEINS IN HUMAN VASCULAR ENDOTHELIAL-CELLS

Most inflammatory agents activate nuclear transcription factor-kappa B (NF-kappa B) which results in expression of genes for cytokines, adhe sion molecules, and enzymes involved in amplification and perpetuation of inflammation. Emodin (3-methyl-1,6,8-trihydroxyanthraquinone) is a n active component from the roots of Polygonum cuspidatum that has bee n reported to exhibit antiinflammatory properties but the mechanism is not known. In the present study we investigated the effects of emodin on the activation of NF-kappa B in human umbelical vein endothelial c ells (EC), Treatment of EC with TNF activated NF-kappa B; preincubatio n with emodin inhibited this activation in a dose- and time-dependent manner. Emodin did not chemically modify NF-kappa B subunits but rathe r inhibited degradation of I kappa B, an inhibitory subunit of NF-kapp a B. Since the promoter regions of ICAM-1, VCAM-1, and ELAM-1 contain NF-kappa B binding sites and these adhesion molecules are involved in the attachment of leukocytes to EC, the effect of emodin on the adhesi on of monocytes to EC and the expression of these adhesion molecules w as also studied. Treatment of EC with TNF for 6 h increased the adhesi on of monocytes to EC, which correlated with increases in cell surface expression of ICAM-1, VCAM-1 and ELAM-1. Pretreatment of EC for Ih wi th emodin inhibited both monocyte-EC attachment and expression of ICAM -1, ELAM-1 and VCAM-1, These results indicate that emodin is a potent inhibitor of NF-kappa B activation and expression of adhesion molecule s and thus could be useful in treating various inflammatory diseases.