In vitro studies of changes in human endothelial cell functions under the effect of imiquimod.

Imiquimod (1-(2-methylpropyl)-1H-imidazo[4,5-c]quinolin-4-amine) is an active immunomodulator with antiviral effects. In addition to its stimulatory effect on cell-mediated immunity, in vivo studies have detected its antiviral and antiangiogenic effects. Possible direct effect of imiquimod on endothelial cells remains not studied. We have shown that imiquimod inhibited proliferation and migration of human endothelial cells (EA.hy 926 strain) in vitro and induced apoptosis (but not necrosis) of endothelial cells and production of IL-6 cytokine. These results suggest that imiquimod inhibits angiogenesis via direct modulation of endothelial cell function.