Selective inhibition of E-selectin, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1 expression by inhibitors of I kappa B-α phosphorylation

The promoters of the E-selectin, vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) genes contain recognition sequences for the inducible nuclear transcription factor kappa B (NF-kappa B). We demonstrate that the appearance of NF-kappa B DNA-binding activity in the nucleus of TNF-alpha-stimulated HUVEC is associated with the rapid phosphorylation and subsequent degradation of I kappa B-alpha, the cytoplasmic inhibitor of NF-kappa B. Serine protease inhibitors prevented the TNF-alpha-induced accumulation of phosphorylated I kappa B-alpha, and prevented I kappa B-alpha degradation and the appearance of NF-kappa B DNA-binding activity. These inhibitors had no direct effect upon the ability of NF-kappa B to bind its cognate recognition sequences, nor upon the DNA-binding activities of other transcription factors. Inhibition of I kappa B-alpha proteolysis resulted in the inhibition of the cytokine- and LPS-induced transcriptional up-regulation and cell-surface expression of E-selectin, VCAM-1, and ICAM-1. In contrast, the TNF-alpha-induced expression of plasminogen activator inhibitor-1 and the constitutive expression of ICAM-2 were unaffected. These inhibitors also had no effect on cellular viability or rates of RNA or protein synthesis. Inhibitors of other proteases and various protein kinases had no effect on the cytokine-induced expression of these endothelial adhesion molecules. These findings indicate that it is possible, using a single pharmacologic agent, to selectively inhibit the expression of the E-selectin, VCAM-1, and ICAM-1 genes without affecting the constitutive or inducible expression of other genes. Pharmacologic inhibition of I kappa B-alpha proteolysis represents a novel approach to the development of anti-inflammatory therapeutics.