Differential influences of bFGF and VEGF on the expression of vascular cell adhesion molecule-1 on human umbilical vein endothelial cells

Abstract

A fundamental feature of inflammation includes angiogenesis, adhesion of leukocytes to vascular endothelium, and entry of leukocytes into inflamed tissues. Recent studies have suggested that angiogenesis and cellular adhesion may be mutually linked processes. Both basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) have been shown to facilitate angiogenesis. However, their roles in the expression of adhesion molecules on the endothelial cells have not been clarified. The current studies therefore examined the effect of bFGF and VEGF on the expression of vascular cell adhesion molecule-1 (VCAM-1) on human umbilical vein endothelial cells (HUVEC) stimulated with tumor necrosis factor alpha (TNF-alpha). HUVEC (1 x 10(4)/well) were incubated in a 96 well microtiter plate with culture medium containing endothelial cell growth supplement (ECGS) for 24 h. After the incubation, culture medium was replaced by ECGS free culture medium with or without TNF-alpha (10 ng/ml), bFGF (10 ng/ml) and VEGF (10 ng/ml), and the culture was further carried out for additional 24 h. The expression of VCAM-1, E-selectin, and intercellular adhesion molecule-1 (ICAM-1) was measured by cell ELISA and the proliferation of HUVEC was measured by MTT colorimetric assay. Soluble VCAM-1 (sVCAM-1) in the supernatants were assessed by ELISA. Although, both bFGF and VEGF supported the proliferation of HUVEC, bFGF, but not VEGF, selectively suppressed the expression of VCAM-1 on HUVEC stimulated with TNF-alpha. The expression of ICAM-1 and E-selectin induced by TNF-alpha was not inhibited by either bFGF or VEGF. In addition, bFGF also decreased the levels of sVCAM-1 in the supernatants of TNF-alpha stimulated HUVEC. The data indicate that bFGF, but not VEGF, suppresses the production of VCAM-1 by HUVEC under stimulation with TNF-alpha. These results therefore suggest that angiogenic cytokines bFGF and VEGF play different roles in the regulation of the expression of adhesion molecules on endothelial cells under inflammation.