Differences in the effects of cytokines on the expression of adhesion molecules in endothelial cells

Objectives.- Expressions of adhesion molecules on arterial endothelial cells are crucial events in initiation of atherosclerosis. Our recent study has shown that endothelial cells express endothelial leukocyte adhesion molecule-1 (ELAM-1) significantly due to stimulation with oxidized LDL, H2O2, or hypoxia. This current study is aimed at investigating temporal relations of the induction of ELAM-1, intercellular adhesion molecule-1 (ICAM-1), and vascular cell: adhesion molecule-1 (VCAM-1) in cultured endothelial cells of the human thoracic aorta. Methods. - The activators examined were interleukin 1 alpha (IL-1 alpha), tumor necrosis factor alpha (TNF alpha), and interferon gamma (IFN gamma). Cells were incubated with each of the cytokines at 10 ng/ml for 0.5-48 hours. The adhesion molecules were determined by enzyme immunoassay. Results. - ELAM-1 appeared after stimulations by IL-1 and TNF alpha; ELAM-1 was induced by DL-l after one hour, while it rose sharply after a 30-min stimulation by TNF alpha. The ICAM-1 expression was observed even in non-stimulated cells and further increased in proportion to duration of stimulation. No significant difference occurred between the effects of IL-1 and TNF alpha on the ICAM-1 expression. Weak expression of VCAM-1 was observed only by TNF alpha after 4- through 24-h stimulation. IFN gamma did not cause any changes in the expression of ELAM-1, VCAM-1, and ICAM-1. Conclusions. - The present data indicate a specific time course for each induction of ELAM-1 and VCAM-1, but not ICAM-1. Therefore, the combination of molecules may play a role for endothelial cells to discriminate monocytes from such other cells as neutrophils and lymphocytes.