PART I.:Roles of LIGHT in atherosclerosis:functional assays toward macrophage and vascular smooth muscle cellPART II.: The mechanisms of statins in the regulation of inducible nitric oxide synthase gene expression on vascular smooth muscle cell

• Main Authors: Chun-yu Wei, 魏淳郁
• Other Authors: Wan-wan Lin
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/17815338084922783620

碩士 === 國立臺灣大學 === 藥理學研究所 === 92 === PART I LIGHT (homologous to lymphotoxins, shows inducible expression, and competes with herpes simplex virus glycoprotein D for herpesvirus entry mediator, a receptor expressed by T lymphocytes) is a member of the tumor necrosis factor superfamily that can interact with lymphotoxin-β receptor (LTβR), herpes virus entry mediator (HVEM), and decoy receptor (DcR3). In this study, in murine macrophages and rat aortic vascular smooth muscle cells (VSMC) expressing both LTβR and HVEM, we showed that LIGHT could induce chemotaxis and oxLDL phagocytic effect toward murine macrophage as well as proliferation and migration effects toward VSMC. Using LIGHT mutant, LIGHT-R228E, and LT�淯 agonist, �埕T�淯, we revealed that the migration and proliferation induced by LIGHT is HVEM-dependent because LIGHT-R228E and �埕T�淯 barely induce these effects in both cell types. LIGHT-induced macrophage migration is associated with activation of signaling kinases, including MAPKs, PI3K/Akt, PKC, Src members, FAK, and transcriptional factors, NF-�羠 and AP-1. Moreover, LIGHT-stimulated NF-�羠 and AP-1 activity were downstream the signaling pathways initiated by adaptor molecules, TRAFs. The proliferation effect in VSMC also was shown by inducing the activation of MAPKs, PI3K/Akt, PKC, and NF-�羠, which lead to alter the expression of cell cycle regulated molecules, p21, p27, p53, cyclins and RB protein. Meanwhile, VSMC migration as assessed by wound-healing model was elicited, and possibly associated with its effects in releasing chemokine IL-8 and expressing MMP-9. In conclusion, we demonstrate that LIGHT is a novel inducer for macrophage migration and lipid uptake, as well as VSMC proliferation and migration. All these effects strongly suggest the important role of LIGHT in atherosclerosis. PART II 　The 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitors, statins, are potent inhibitors of cholesterol synthesis and have wide therapeutic use in cardiovascular diseases. Recent evidence, however, suggests that the beneficial effects of statins may extend beyond their action on serum cholesterol levels. Although statins have been shown to reduce progression of atherosclerosis, little is known about mechanism by which statins affect iNOS expression. In this study, we investigated the effects of fluvastatin, lovastatin, pravastatin and atorvastatin on cultured rat vascular smooth muscle cells (VSMC). We found fluvastatin can inhibit LPS-induced iNOS expression and NO production, while they can potentiate IL-1��-elicited responses. In studying the activity of NF-�羠, which plays an important role for iNOS gene induction, we found that fluvastatin can increase IL-1��-induced p65 nuclear translocation and NF-�羠 activity, while inhibit those induced by LPS. The potentiation effects of fluvastatin on IL-1��-induced NO production, iNOS expression, NF-�羠 activation and p65 nuclear translocation were all mimicked by a ROCK inhibitor, Y-27632. IKK kinase assay showed that fluvastatin can downregulate LPS-induced IKK activity. Y-27632 itself has minimal effect on LPS-induced IKK activation, while enhances the response of IL-1��. Studies on examining ROCK activity showed LPS can downregulate constitutive ROCK activity, while IL-1�� oppositely increases ROCK activity. Taken together these data suggest ROCK is a crucial negative regulator of IKK/ NF-�羠 signaling pathway in VSMC, and this negative control is existing in the action IL-1��, but is absent in the action of LPS. Through abrogating the function of this negative regulator, statins and ROCK inhibitor thus differentially regulate iNOS expression induced by LPS and IL-1β in VSMC. These effects of statins possibly may contribute to the prevention effect on restenosis, and strengthen the pleiotropic actions of statins in anti-inflammation and anti-atherosclerosis.