IL-4-induced oxidative stress upregulates VCAM-1 gene expression in human endothelial cells

Vascular cell adhesion molecule-1 (VCAM-1) is expressed in early stages of atherosclerosis; however, the mechanisms of its upregulation are not fully understood. In the present study, we examined the effects of interleukin-4 (IL-4) on VCAM-1 gene expression and its transcriptional regulatory mechani sm in human umbilical vein endothelial cells (HUVEC). Reverse transcription -polymerase chain reaction showed that VCAM-1 mRNA was induced in IL-4-trea ted HUVEC in a time- and dose-dependent manner. Among known transcription f actors that have binding sites in the promoter region of the VCAM-1 gene, I L-4 activated only SP-1. In contrast, nuclear factor-kappaB (NF-kappaB), ac tivator protein-1 (AP-1) and interferon regulatory factor-1 (IRF-1), which also have consensus binding sequences in the 5'-flanking region of the huma n VCAM-1 gene, were not activated. The role of SP-1 in IL-4-induced VCAM-1 expression was confirmed in HUVEC transfected with a reporter construct of the VCAM-1 promoter with mutated SP-1 binding site. As IL-4 treatment of HU VEC enhanced the intracellular oxidizing potential, as indicated by an incr ease in 2',7'-dichlorofluorescein (DCF) fluorescence. we studied the effect of antioxidants on IL-4-induced VCAM-1 expression. Pretreatment of HUVEC w ith pyrrolidine dithiocarbamate (PDTC) or N-acetylcysteine (NAC) completely prevented IL-4-induced VCAM-1 expression. In addition. PDTC inhibited IL-4 -related activation of SP-1. These results suggest that IL-1-induced oxidat ive stress upregulates the expression of VCAM-1 gene in HUVEC at transcript ional levels via activation of SP-1 transcription factor. In contrast, NF-k appaB, AP-1 or IRF-1 do not appear to be involved in the signal transductio n cascade. (C) 2000 Academic Press.