Indole-3-carbinol is a potent inhibitor of ischemia-reperfusion-induced inflammation

Abstract

Background: Ischemiaereperfusion (I/R) induces tissue inflammation, which is characterized by an increased leukocyteeendothelial cell interaction and leukocyte transmigration. These processes are mediated by the activation of the nuclear factor (NF) kB signaling pathway, resulting in an elevated expression of specific adhesion molecules. The phytochemical indole-3-carbinol (I3C) has been shown to exert anti-inflammatory effects by interfering with NFkB signal transduction. The aim of the present study was to investigate whether I3C is capable of counteracting the pathogenesis of I/R injury. Materials and methods: We investigated the inhibitory effect of I3C on endothelial surface protein expression during hypoxia and reoxygenation by flow cytometry. Moreover, the subcellular localization of NFkB was analyzed by immunofluorescence and Western blot. Adhesion protein levels on leukocytes after tumor necrosis factor-a stimulation were determined using flow cytometry. Finally, leukocyteeendothelial cell interaction and leukocyte transmigration during I/R was investigated in dorsal skinfold chambers of BALB/c mice by means of repetitive intravital fluorescence microscopy and immunohistochemistry. Results: I3C suppressed the expression of E-selectin and intercellular adhesion molecule-1 on human dermal microvascular endothelial cells by reducing the transcriptional activity of NFkB. Furthermore, surface protein levels of macrophage-1 antigen as well as activated lymphocyte functioneassociated antigen-1 were markedly reduced on I3C-treated leukocytes. In vivo, I3C treatment decreased the numbers of adherent and transmigrated leukocytes. This was associated with a reduced macromolecular leakage when compared with vehicle-treated controls. Conclusions: These novel results indicate that I3C reduces the expression of endothelial and leukocytic adhesion proteins, resulting in attenuated leukocyteeendothelial cell interactions during I/R. Accordingly, dietary supplements containing I3C may be beneficial for the treatment of I/R-induced inflammation.