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Abstract
Inflammatory processes of vascular endothelial cells play a key role in the development ofatherosclerosis. We determined the anti-inflammatory effects and mechanisms of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on LPS-treated human umbilical vein endothelial cells (HUVECs) to evaluate their cardioprotective potential. Cells were pretreated with DHA, EPA, or troglitazone prior to activation with LPS. Expression of COX-2, prostaglandin E2 (PGE2) and IL-6 production, and NF-κB activity were measured by Western blot, ELISA, and luciferase activity, respectively. Results showed that EPA, DHA, or troglitazone significantly reduced COX-2 expression, NF-κB luciferase activity, and PGE2 and IL-6 production in a dose-dependent fashion. Interestingly, low doses (10 μM) of DHA and EPA, but not troglitozone, significantly increased the activity of NF-κB in resting HUVECs. Our study suggests that while DHA, EPA, and troglitazone may be protective on HUVECs under inflammatory conditions in a dose-dependent manner. However there may be some negative effects when the concentrations are abnormally low, even in normal endothelium.
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Fig. 1.
Inhibitory effect of DHA (A), EPA (B), or troglitazone (C) on PGE2 production by LPS-treated HUVECs. The results were confirmed by three experiments (n=6). Significance compared with the control, ∗p<0.05; significance compared with LPS, †p<0.05.
Fig. 2.
Inhibitory effect of DHA (A), EPA (B), or troglitazone (C) on IL-6 production by LPS-treated HUVECs. The results were confirmed by three experiments (n=6). Significance compared with the control, ∗∗p<0.01; significance compared with LPS, †p<0.05, ††p<0.01.
Fig. 3.
Inhibitory effect of DHA (A), EPA (B), or troglitazone (C) on the expression of COX-2. The results were confirmed by three experiments (n=3). Significance compared with the control, ∗∗p <0.01; significance compared with LPS, †p<0.05, ††p<0.01.
Fig. 4.
Inhibition of LPS-induced NF-κB-luciferase activity by DHA, EPA, or troglitazone. Cells were transfected with 2 μg of NF-κB-luciferase, allowed to recover for 24 h, and then stimulated with LPS in the absence of agents (A) or in the presence of DHA (B), EPA (C), or troglitazone (D). Cells were harvested 8 h after treatment, and luciferase activities were determined. The results were confirmed by three experiments (n=6). Significance compared with NF-κB transfected control, ∗p<0.05, ∗∗p<0.01; significance compared with NF-κB+LPS, †p<0.05, ††p<0.01. (E) Effect of DHA, EPA, or troglitazone on PPARγ expression by HUVECs. The results were confirmed by three experiments (n=6). Significance compared with the control, ††p<0.01.
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