Pioglitazone decreased CD40/CD40L expression on human umbilical vein endothelial cells induced by oxidized low-density lipoprotein.

BACKGROUND

The CD40/CD40 ligand pathway mediated inflammatory processes are important in atherogenesis and the formation of the intraplaque lipid pool. We tested the hypothesis that pioglitazone could decrease lectin-like oxLDL receptor-1 (LOX-1) and CD40/CD40L expression on human umbilical vein endothelial cells (HUVECs) induced by oxidized low-density lipoprotein (oxLDL).

METHODS

HUVECs were incubated with oxLDL for 24h with or without pretreated by pioglitazone. Expression of CD40/CD40L on the cell surface was detected by flow cytometry. CD40/CD40L and LOX-1 mRNA expression were evaluated by RT-PCR. The expression of LOX-1 on HUVECs was determined by cell immunohistochemistry.

RESULTS

OxLDL increased the expression of CD40 and CD40L in a dose- and time-dependent manner. Pretreatment of HUVECs with pioglitazone (1 and 10 micromol/l) for 60 min decreased the expression of CD40 mRNA induced by oxLDL by 16% and 52%, respectively (both P<0.05). Pretreatment of HUVECs with pioglitazone (1 and 10 micromol/l) for 60 min decreased the expression of CD40L mRNA induced by oxLDL by 16% and 43% (both P<0.05). Also, pretreatment of HUVECs with pioglitazone (1 and 10 micromol/l) for 60 min also significantly decreased CD40 and CD40L expression on HUVECs induced by oxLDL in a concentration-dependent manner. Pretreatment of HUVECs with pioglitazone (1 and 10 micromol/l) decreased oxLDL induced upregulation mRNA of LOX-1 by 11% and 28%, respectively. Furthermore, through immunohistochemistry, we found that pioglitazone could decrease the LOX-1 expression on HUVECs induced by oxLDL.

CONCLUSION

Pioglitazone inhibited the upregulation of LOX-1 on HUVECs elicited by oxLDL and subsequently decreased HUVECs CD40/CD40L expression induced by oxLDL. These observations provided novel insight into a potential novel anti-inflammatory pathway of thiazolidinediones.