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Oxidative stress is recognized as one of the most important contributing factors to the development of atherosclerosis. Oxidized low-density lipoprotein (ox-LDL) can induce vascular reactive oxygen species (ROS) production, trigger endothelial dysfunction and initiate the progression of atherosclerosis. Previous studies have demonstrated that thioredoxin-1 (Trx) is one of the key regulators of intracellular redox, which is pivotal in atherogenesis. However, the regulation mechanism is still unclear. In this study, we investigated the effects of Trx1 on NADPH oxidase in human umbilical vein endothelial cells (HUVECs), whose ROS level is mainly produced by NADPH oxidase, especially Nox4 isoform. Our data demonstrated that Trx decreased NADPH oxidase activity, ROS production and ICAM-1 expression in ox-LDL treated HUVECs. Genetic gain-of-function and loss-of-function studies showed that Trx1 suppressed ox-LDL-induced Nox4 and p22phox expression. A co-immunoprecipitation assay indicated that Trx1 decreased Nox4-p22phox complex level during ox-LDL stimulation. Transient transfection of Nox4 and p22phox significantly increased intracellular ROS generation, which could be blocked by Trx overexpression. In addition, Trx overexpression also prevented ox-LDL-induced Nox2 and Rac1 protein levels. These results suggest that Trx suppresses NADPH oxidase activity in vascular endothelia under pathological conditions and may prevent the initiation of atherosclerosis by attenuating exceeding ROS production. [ABSTRACT FROM AUTHOR]

Background: Atherosclerosis is a chronic inflammation disease which is initiated by endothelial cell injury Oxidized low-density lipoprotein (ox-LDL) is directly associated with chronic vascular inflammation. Many transcription factors take part in the initiation and progression of atherosclerosis. As a transcription factor mainly expressed in cardiovascular system, T-box20 (Tbx20) plays an important role in embryonic cardiovascular system development and homeostasis. However, the role of Tbx20 in endothelial cell injury and atherosclerosis is still not clear. We showed that Tbx20 might affect ox-LDL-induced inflammatory responses in human umbilical vein endothelial cells (HUVECs). Methods and Results: First, Tbx20 expression was down regulated in the C57BL/6 mice with high-fat diet-induced artery injury, which was accompanied by elevated reactive oxygen species (ROS) generation and cell adhesion molecule expression. Second, ox-LDL led to concurrent decreased Tbx20 expression and increased levels of ROS and adhesion molecules in the HUVECs. Third, over-expression of Tbx20 by adenovirus reduced ox-LDL-induced HUVEC injury via attenuation of ROS generation and cell adhesion molecule expression. Fourth, knock down of Tbx20 by siRNA significantly increased adhesion molecule expression and decreased cell viability. Moreover, Tbx20 could directly regulate PPAR-γ expression, as shown by Tbx20 knock down and PPAR-γ inhibition, which significantly reversed Tbx20's HUVEC protection effect. Conclusions: These results indicate that misregulation of Tbx20 could reduce HUVEC tolerance of ox-LDL-induced cell injury, suggesting that Tbx20 might be a crucial regulator and potential therapeutic target for atherosclerosis. © 2013 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Atherosclerosis is a chronic inflammation disease that is initiated by endothelial cell injury. Oxidized low-density lipoprotein (ox-LDL) is directly associated with chronic vascular inflammation. To understand whether thioredoxin1 (Trx1) participates in an antiinflammatory defense mechanism in atherosclerosis, we investigated the effect of Trx1 on the expression of two adhesion molecules, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1), in human umbilical vein endothelial cells (HUVECs). Thioredoxin1 and dominant-negative mutant thioredoxin1 (TD) were transiently overexpressed using adenovirus vector gene transfer. Our data showed that Trx1 overexpression suppressed ox-LDL-induced adhesion molecule expression in HUVECs. The overexpression of Trx1 promoted ox-LDL-induced Smad3 phosphorylation and nuclear translocation. A co-immunoprecipitation assay indicated that Smad3 continued to interact with Trx1 with or without ox-LDL stimulation. These results suggest that Trx1 inherently suppresses VCAM-1 and ICAM-1 expression in vascular endothelia and may prevent the initiation of atherosclerosis by attenuating adhesion molecule expression. The enhancement of Smad3 phosphorylation and nuclear expression appears to be primarily responsible for the Trx1-induced downregulation of adhesion molecules. [ABSTRACT FROM AUTHOR]

Oxidized low-density lipoprotein (ox-LDL) is an important risk factor in the development of atherosclerosis. LOX-1, a lectin-like receptor for ox-LDL, is present primarily on endothelial cells and upregulated by ox-LDL, tumor necrosis factor a, shear stress, and cytokines in atherosclerosis. Recent studies demonstrated that ginkgolide B, a platelet-activating factor receptor antagonist, has antiinflammatory and antioxidant effects on endothelial and nerve cells. The present study investigated the effects of ginkgolide B on LOX-1 expression and the possible mechanism of action. Our results showed that ginkgolide B inhibited LOX-1 and intercellular cell adhesion molecule-1 (ICAM-1) expression in ox-LDL-stimulated endothelial cells through a mechanism associated with the attenuation of Akt activation. Similar data were obtained by silencing Akt and LY294002. We also evaluated Sirt1 and nuclear factor erythroid 2-related factor 2 (Nrf2) expression. These molecules play a protective role in endothelial cell injury. The results showed that ginkgolide B increased Sirt1 expression in ox-LDL-treated cells. The inhibitory effects of ginkgolide B on LOX-1 and ICAM-1 expression were reduced in Sirt1 siRNA-transfected cells. Nrf2 expression was increased in ox-LDL-treated cells, and ginkgolide B downregulated Nrf2 expression. These results suggest that ginkgolide B reduces Nrf2 expression by inhibiting LOX-1 expression, consequently reducing oxidative stress injury in ox-LDL-stimulated cells. Altogether, these results indicate that the protective effect of ginkgolide B on endothelial cells may be attributable to a decrease in LOX-1 expression and an increase in Sirt1 expression in ox-LDL-stimulated endothelial cells, the mechanism of which is linked to the inhibition of Akt activation. Ginkgolide B may be a multiple-target drug that exerts protective effects in ox-LDL-treated human umbilical vein endothelial cells. [ABSTRACT FROM AUTHOR]