Ox-LDL plays dual effect in modulating expression of inflammatory molecules through LOX-1 pathway in human umbilical vein endothelial cells.

Lectin-like oxidized low-density lipoprotein receptor1 (LOX-1) has been recognized to be the major endothelial receptor for oxidized low-density lipoprotein (ox-LDL). Ox-LDL has been reported to induce the expression of inflammatory adhesive molecules from vascular endothelium. However, the mechanism of this action has not been fully elucidated. Peroxisome proliferation-activated receptor-gamma (PPARgamma) regulates the expression of inflammatory adhesive molecules. The present study was carried out to investigate the role of LOX-1-PPARgamma pathway in regulating expression of adhesion molecules, ICAM-1 and E-selectin in HUVECs. Ox-LDL increased the expression of ICAM-1 and E-selectin in a concentration (10-50 microg/ml)--and time (6-36 hours)--dependent manners. These effects were significantly inhibited by pretreatment of HUVECs with polyinosonic acid or carrageenan. Preincubating HUVECs with 15d-PGJ2 attenuated the expression of ICAM-1 and E-selectin in response to ox-LDL, although ox-LDL stimulated the expression of PPARgamma. Upregulation of ICAM-1 and E-selectin mediated by ox-LDL were inhibited more significantly by the combination of 15d-PGJ2 and polyinosonic acid as compared to either 15d-PGJ2 or polyinosonic acid alone. The results suggested that ox-LDL through its receptor LOX-1 promotes pro-inflammation response by increasing expression of ICAM-1 and E-selectin, simultaneously activates PPARgamma triggering cellular anti-inflammation response in protection from the inflammation lesions in HUVECs.