Cytokine-inducible CD40 expression in human endothelial cells is mediated by interferon regulatory factor-1

Given the significance of CD40-CD40 ligand interactions in chronic inflammatory diseases including atherosclerosis, the transcriptional regulation of CD40 expression as a potential therapeutic target was investigated in human umbilical vein cultured endothelial cells. Exposure to interferon-gamma (IFN-gamma) plus tumor necrosis factor-a resulted in a marked synergistic de novo expression of CD40, which, according to electrophoretic mobility shift analysis, was attributable to activation of the transcription factors nuclear factor-kappaB (NF-kappaB), signal transducer and activator of transcription-1 (STAT-1), and interferon regulatory factor-1 (IRF-1). Subsequent time-course studies revealed that de novo synthesis of IRF-1 preceded that of CD40. Decoy oligodeoxynucleotide (ODN) neutralization of STAT-1 or IRF-1, but not of NF-kappaB, inhibited cytokine-stimulated CD40 expression by 60% at both the mRNA and protein levels, and this effect was mimicked by antisense ODN blockade of IRF-1 synthesis. In contrast, CD40 expression in response to IFN-gamma stimulation was sensitive to neutralization of STAT-1 only. These findings suggest that depending on the cytokine composition, CD40 expression In human endothelial cells under proinflammatory conditions Is governed by STAT-1 either directly or Indirectly through de novo synthesis of IRF-1. Moreover, decoy ODN neutralization of these transcription factors may provide a novel therapeutic option for Interfering with CD40-CD40 ligand-mediated Inflammatory responses in vivo. (Blood. 2002;99:520-525) (C) 2002 by The American Society of Hematology.