Vol. 62, Issue 4, 856-863, October 2002

Tranilast Inhibits Cytokine-Induced Nuclear Factor B Activation in Vascular Endothelial Cells

Martin Spiecker, Ioana Lorenz, Nikolaus Marx, and Harald Darius

Department of Medicine II, University of Bochum, Bochum, Germany (M.S.); Department of Medicine II, University of Mainz, Mainz, Germany (I.L., H.D.); Department of Medicine II, University of Ulm, Ulm, Germany (N.M.)

Tranilast [N-(3,4-dimethoxycinnamoyl)anthranilic acid] inhibits vascular inflammation. However, the relevant anti-inflammatory mechanisms are not completely understood. We studied the effects of tranilast on nuclear factor-B (NF-B)-dependent endothelial cell adhesion molecule expression and transcriptional regulation. Cultured human umbilical vein endothelial cells were preincubated with 12.5 to 100 µg/ml tranilast. Tumor necrosis factor- (TNF-)-induced endothelial VCAM-1, ICAM-1, and E-selectin surface expression was inhibited dose dependently. Maximal inhibition achieved with 100 µg/ml tranilast was 38 ± 6.9, 31.8 ± 1.5, and 31.9 ± 1.9%, respectively (mean ± S.E.M., p < 0.001, n = 5). Secretion of interleukin 6, which is also NF-B-sensitive, was significantly inhibited by tranilast. Endothelial MHC-I expression, which is independent of NF-B, was not inhibited. Although cytokine-induced degradation of NF-B inhibitor proteins (IB-, -, and -), nuclear translocation of NF-B, and binding of NF-B to B cis-acting elements in the adhesion molecule promoters were not affected by tranilast, ICAM-1-B and E-selectin-B reporter gene activity was inhibited by 53% (n = 5, p < 0.01) and 51% (n = 5, p < 0.001), respectively. In contrast, using SP-1 and C/EBP constructs, reporter gene activity was not altered. Expression of the transcriptional coactivator cAMP response element binding protein binding protein (CBP) was inhibited by tranilast, resulting in a loss of interaction between NF-B and CBP. Therefore, in therapeutically relevant concentrations (50 µg/ml), tranilast inhibits NF-B-dependent transcriptional activation by interfering with the NF-B/CBP association. We propose that inhibition of NF-B dependent gene transcription contributes to the anti-inflammatory effects of tranilast.