Oxidized LDL-mediated monocyte adhesion to endothelial cells does not involve NF kappa B

Oxidised LDL (oxLDL) is a key pathogenic mediator of atherogenesis, exhibit ing many proatherogenic properties. We have examined the effect of oxLDL on monocyte adhesion in the endothelial cell line, EA.hy 926. This has includ ed the role of endothelial cell adhesion molecule expression (ICAM-1 and VC AM-1), monocyte chemoattractant protein-1 (MCP-1), and the transcription fa ctor NF kappaB in this interaction. In response to oxLDL (10-100 mug/ml), m onocyte adhesion to cells increased dose-dependently. Adhesion of oxLDL at 100 mug/ml was equivalent to that seen with TNF alpha (10 ng/ml). Unmodifie d LDL (nLDL, 100 ug/ml) had no effect. Both oxLDL and nLDL increased MCP-1 mRNA levels. Interestingly, oxLDL had no effect on the expression of ICAM-1 and VCAM-1. In addition NF kappaB was not activated as shown by western bl ots of I kappaB-alpha degradation and electrophoretic mobility shift assay. In summary these data show that increased monocyte adhesion to EA.hy 926 c ells occurs independently of ICAM-1, VCAM-1, and NF kappaB activation and m ay involve novel adhesive mechanisms. (C) 2001 Academic Press.