Inhibitory effect of Thuja orientalis on TNF-α-induced vascular inflammation.

Vascular inflammation is involved in the initiation and progression of vascular diseases including atherosclerosis. While conducting in vitro screening of 600 medicinal plant extracts, an aqueous extract of Thuja orientalis (ATO) was found to exhibit antiinflammatory activity in human umbilical vein endothelial cells (HUVEC). In the current study, the antiinflammatory activity of ATO and possible mechanisms for this were investigated in HUVEC. Preincubation with ATO (20 μg/mL) suppressed tumor necrosis factor-α (TNF-α)-induced expression of adhesion molecules including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin at both the protein and mRNA levels. ATO also inhibited U937 monocyte adhesion to HUVEC stimulated by TNF-α. In addition, ATO attenuated TNF-α-induced p65 NF-κB translocation into the nucleus and phosphorylation of IκB-α. Furthermore, ATO significantly inhibited TNF-α-induced intracellular reactive oxygen species (ROS) production. Overall, the present data suggest that ATO can suppress TNF-α-induced vascular inflammatory processes, possibly via inhibition of ROS and NF-κB activation, in HUVEC.