Dissecting the anti-inflammatory effects of Viscum album: inhibition of cytokine-induced expression of cyclooxygenase-2 and secretion of prostaglandin E2

International audience; Reports unraveling the beneficial effects of Viscum album (VA) preparations as complementary therapies for cancer have increasingly revealed the underlying molecular and cellular mechanisms, which encompass cytotoxic properties, induction of apoptosis, inhibition of angiogenesis and several other immunomodulatory mechanisms. In addition to their propitious relevance to cancer therapy, VA preparations are also relevant for the treatment of several inflammatory pathologies. In view of the intricate association of inflammation and cancer and the fact that several anti-tumor phytotherapeutics exert potent anti-inflammatory effects, we believe that an anti-inflammatory effect is responsible for the therapeutic benefits of VA preparations. One of the underlying molecular mechanisms of this inflammatory response is the selective down-regulation of the cyclo-oxygenase (COX)-2-mediated cytokine-induced secretion of prostaglandin E2 (PGE2). This inhibitory action has been associated with reduced expression of COX-2, without modulating COX-1 expression. This mechanism is associated with VA-induced destabilization of COX-2 mRNA, thereby depleting the functional COX-2 mRNA available for protein synthesis and for subsequent induction of secretion of PGE2. Together, these results demonstrate a novel anti-inflammatory mechanism of action of VA preparation, wherein VAQUSpez an anti-inflammatory effect by inhibiting cytokine-induced PGE2 via selective inhibition of COX-2 and destabilization of COX-2 mRNA.