A novel thiazolidinedione MCC-555 down-regulates tumor necrosis factor-α-induced expression of vascular cell adhesion molecule-1 in vascular endothelial cells

Thiazolidinediones (TZDs) are anti-diabetic agents that enhance insulin sensitivity through activating peroxisome proliferator-activated receptor (PPAR) γ. Besides their glucose-lowering effects, TZDs are shown to exhibit anti-inflammatory properties in vascular cells, although their precise molecular mechanisms are unknown. In the present study, we examined the effects of a novel TZD MCC-555, which has unique characteristics of ability to activate not only PPARγ but also PPARα and PPARδ on vascular cell adhesion molecule-1 (VCAM-1) expression in vascular endothelial cells (ECs). Human aortic ECs were treated with MCC-555, followed by stimulation with tumor necrosis factor (TNF)-α. Cell surface VCAM-1 protein expression and human monocytoid U937 cell adhesion to these cells were determined. MCC-555 efficiently inhibited TNF-α-stimulated VCAM-11expression and U937 cell adhesion. Transient transfection of bovine aortic ECs with a VCAM-1 promoter construct revealed that MCC-555 inhibited TNF-α-induced VCAM-1 promoter activity. Electrophoretic mobility-shift assay demonstrated that MCC-555 reduced the amount of nuclear factor-κB (NF-κB) bound to its recognition site on the VCAM-1 promoter. The considered PPARδ activator GW501516 and the considered PPARα activator fenofibrate also inhibited TNF-α-induced VCAM-1 expression, whereas pioglitazone and rosiglitazone did not. These results indicate that MCC-555 is a strong TZD agent to inhibit the cytokine-induced VCAM-1 expression in vascular ECs. This effect is exerted probably through activation of PPARα and/or PPARδ, rather than PPARγ, mediating down-regulation of NF-κB activity.