CYP450 dietary inhibitors attenuate TNF-alpha-stimulated endothelial molecule expression and leukocyte adhesion.

Enhanced expression of mucosal addressin cell adhesion molecule-1 (MAdCAM-1) and other endothelial cell adhesion molecules (ECAMs) are associated with the onset and progression of inflammatory bowel disease (IBD). We show in this study that two cytochrome p-450 (CYP450) inhibitors from Citrus paradis (grapefruit), bergamottin, and 6',7'-dihydroxybergamottin (DHB) block tumor necrosis factor (TNF)-alpha-stimulated expression of MAdCAM-1 in cultured endothelial cells and also reduce alpha(4)beta(7)-dependent lymphocyte adhesion. Bergamottin (20-50 microM) or DHB (10-30 microM) pretreatment dose-dependently reduced TNF-alpha-mediated expression of MAdCAM-1 and lymphocyte adhesion. Bergamottin and DHB also prevented expression of two other ECAMs, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 (but not E-selectin). SKF-525a, a specific CYP450 inhibitor, also blocked the expression of MAdCAM-1 mediated by TNF-alpha. Similar to SKF-525a (20 microM), bergamottin (20 microM) and DHB (20 microM) directly inhibited the activity of CYP450 3A4. These results suggest that natural CYP450 inhibitors may be effective in reducing ECAM expression and leukocyte adhesion and therefore be useful in the clinical treatment of inflammatory states like IBD.