| Summary: | 博士 === 國立陽明大學 === 生化暨分子生物研究所 === 103 === Dietary polyunsaturated fatty acids (PUFAs) alleviate the progression of cardiovascular disease, but the underlying mechanisms within vascular cells remain unclear. The aim of this study was to investigate the biological function and regulatory mechanisms of PUFAs in the human aortic endothelial cells (HAECs), HepG2 cells and the liver of apolipoprotein E (apo E)-knockout mice. In the studies of vascular cells, our results showed that n-3 PUFAs docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) remarkably attenuated lipopolysaccharide (LPS)-induced the adhesion of THP-1 monocytes to HAECs, probably through inhibiting the expression of vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1). Using lipid raft isolation and confocal microscopy, we found that DHA and EPA suppressed the translocation of toll-like receptor 4 (TLR4) into lipid rafts in HAECs. Furthermore, DHA and EPA inhibited the ubiquitination and translocation of TNF receptor-associated factor-6 (TRAF6), and the phosphorylation of transforming growth factor-beta (TGF beta)-activated kinase 1 (TAK1), p38, and IkappaBalpha. We demonstrated that DHA reduced the phosphorylation of PKR, but EPA increased the expression of A20 in HAECs. Additionally, silencing of A20 reversed the inhibitory effect of EPA on the expression of adhesion molecules.
The liver is the essential metabolic center, which aids in maintaining health via diverse biological actions. The present study also used different PUFAs including DHA, EPA, arachidonic acid (AA), or linoleic acid (LA) to fed apoE-knockout mice for ten weeks. Plasma levels of triacylglycerol were significantly decreased in the DHA-fed and EPA-fed mice compared to those of the control mice. In contrast, plasma total cholesterol levels were significantly higher in the LA-fed group, while plasma levels of HDL-cholesterol and LDL-cholesterol were not statistically different among the five groups. Additionally, we investigated how n-3 PUFAs modulate the inflammatory response induced by interleukin (IL)-1β and IL-6 in HepG2 cells. The results showed that n-3 PUFAs inhibited the activation of nuclear factor-kappaB (NF-kappaB), the phosphorylation of nuclear signal transducer and activator of transcription 3 (STAT3) and the production of C-reactive protein (CRP) in HepG2 cells. Taken together, n-3 PUFAs exert their anti-inflammatory properties through differential molecular mechanisms in HAECs and HepG2 cells, suggesting promising strategies for the prevention of inflammatory diseases such as atherosclerosis.
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