Isothiocyanates protect against oxidized LDL-induced endothelial dysfunction by upregulating Nrf2-dependent antioxidation and suppressing NFκB activation.

Oxidative stress plays a pivotal role in the pathophysiology of cardiovascular diseases. Oxidized low-density lipoprotein (oxLDL) is a key contributor to atherogenesis through multiple mechanisms. In this study, we investigated the protection by three structurally related isothiocyanates, i.e., sulforaphane (SFN), benzyl isothiocyanate (BITC), and phenethyl isocyanate (PEITC), against oxLDL-induced leukocyte adhesion to vascular endothelium and the mechanism involved. The protection against oxLDL-induced endothelial dysfunction by isothiocyanates was studied in human umbilical vein endothelial cells (HUVECs). oxLDL increased reactive oxygen species (ROS) production, stimulated nuclear factor-kappaB (NFκB) activation, and enhanced intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), and E-selectin expression in HUVECs, which led to promotion of monocyte adhesion to HUVECs. Treatment with SFN, BITC, and PEITC (0-10 μM) dose-dependently induced heme oxygenase (HO)-1, glutamate cysteine ligase (GCL) catalytic and modifier subunit expression, intracellular glutathione content, and antioxidant response element (ARE)-luciferase reporter activity. SFN, BITC, and PEITC pretreatment reversed oxLDL-induced ROS production, NFκB nuclear translocation, κB-reporter activity, ICAM-1, VCAM-1, and E-selectin expression, and monocyte adhesion to endothelial cells. Both heme oxygenase 1 (HO-1) and nuclear factor erythroid 2-related factor 2 (Nrf2) knockdown attenuated the isothiocyanate inhibition of oxLDL-induced ROS production, κB-reporter activity, and adhesion molecule expression. SFN, BITC, and PEITC protect against oxLDL-induced endothelial damage by upregulating Nrf2-dependent HO-1 and GCL expression, which leads to inhibition of NFκB activation and ICAM-1, VCAM-1, and E-selectin expression.

Huang CS ，Lin AH ，Liu CT ，Tsai CW ，Chang IS ，Chen HW ，Lii CK ... -  《-》

Shikonin inhibits oxidized LDL-induced monocyte adhesion by suppressing NFκB activation via up-regulation of PI3K/Akt/Nrf2-dependent antioxidation in EA.hy926 endothelial cells.

Oxidized low-density lipoprotein (oxLDL) is a key contributor to atherogenesis through multiple mechanisms, including the reactive oxygen species (ROS)-mediated nuclear factor-kappaB (NFκB) signaling pathway. Although shikonin, one of the main active components isolated from the Chinese herb Lithospermum erythrorhizon, has been shown to possess cardioprotective, antioxidative, and anti-inflammatory effects, the mechanisms underlying these actions are not well understood. In this study, we used EA.hy926 endothelial-like cells to examine the anti-atherogenic activity of shikonin. Shikonin (0-1 μM) concentration-dependently induced heme oxygenase-1, glutamate cysteine ligase modifier subunit, catalase, superoxide dismutase 1, glutathione peroxidase 1, and glutathione reductase protein and mRNA expression and glutathione content via activation of the phosphatidylinositol 3-kinase (PI3K)/Akt/Nrf2 signaling pathway. In the presence of oxLDL (40 μg/ml), shikonin pretreatment reversed oxLDL-induced ROS production, antioxidant response element reporter activity, NFκB nuclear translocation, and intercellular adhesion molecule (ICAM)-1 and E-selectin expression and suppressed the increase of monocyte adhesion to endothelial cells. Nrf2 knockdown by using RNA interference attenuated the ability of shikonin to inhibit oxLDL-induced NFκB DNA binding activity, adhesion molecule expression, and monocyte adhesion. Taken together, these results suggest that shikonin protects against oxLDL-induced endothelial damage by suppressing ROS/NFκB-mediated ICAM-1 and E-selectin expression via up-regulation of PI3K/Akt/Nrf2-dependent antioxidant enzyme expression.

Huang CS ，Lin AH ，Yang TC ，Liu KL ，Chen HW ，Lii CK ... -  《-》

Functional dissection of Nrf2-dependent phase II genes in vascular inflammation and endotoxic injury using Keap1 siRNA.

Keap1 is a cytoplasmic repressor of the transcription factor Nrf2, and its degradation induces Nrf2 activation, leading to upregulation of antioxidant phase II genes. We investigated the roles of phase II genes in vascular inflammation and septic injury using Keap1 siRNA and elucidated its underlying mechanism. Selective knockdown of Keap1 with siRNA promoted Nrf2-dependent expression of phase II genes in endothelial cells, such as heme oxygenase-1 (HO-1), glutamate-cysteine ligase (GCL), and peroxiredoxin-1 (Prx1), resulting in the elevation of cellular glutathione levels and suppression of tumor necrosis factor (TNF)-α-induced intracellular H(2)O(2) accumulation. Keap1 knockdown inhibited TNF-α-induced expression of intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) by suppressing NF-κB activation via inhibition of its upstream modulators, Akt, NIK, and IKK, resulting in the elevation of monocyte adhesion to endothelial cells. Importantly, these events were reversed by HO-1 and GCL inhibitors and Prx1-specific siRNA. Keap1 knockdown also inhibited endotoxin-induced expression of inducible nitric oxide synthase (iNOS) and TNF-α by upregulating HO-1, GCL, and Prx1 expression in macrophages. Moreover, in vivo Keap1 knockdown increased the expression of phase II genes and suppressed the expression of ICAM-1, VCAM-1, iNOS, and TNF-α in an endotoxemic mouse model, resulting in significant protection against liver and lung injuries and lethality. Our results indicate that Keap1 knockdown prevents NF-κB-mediated vascular inflammation and endotoxic shock by suppressing NF-κB-mediated inflammatory gene expression via upregulation of Nrf2-mediated antioxidant genes. Thus, siRNA targeting Keap1 may provide a new therapeutic approach for inflammation-associated vascular diseases and sepsis.

Kim JH ，Choi YK ，Lee KS ，Cho DH ，Baek YY ，Lee DK ，Ha KS ，Choe J ，Won MH ，Jeoung D ，Lee H ，Kwon YG ，Kim YM ... -  《-》

Activation of Nrf2/HO-1 signaling: An important molecular mechanism of herbal medicine in the treatment of atherosclerosis via the protection of vascular endothelial cells from oxidative stress.

Recently, Nrf2/HO-1 has received extensive attention as the main regulatory pathway of intracellular defense against oxidative stress and is considered an ideal target for alleviating endothelial cell (EC) injury. This paper aimed to summarized the natural monomers/extracts that potentially exert protective effects against oxidative stress in ECs. A literature search was carried out regarding our topic with the keywords of "atherosclerosis" or "Nrf2/HO-1" or "vascular endothelial cells" or "oxidative stress" or "Herbal medicine" or "natural products" or "natural extracts" or "natural compounds" or "traditional Chinese medicines" based on classic books of herbal medicine and scientific databases including Pubmed, SciFinder, Scopus, the Web of Science, GoogleScholar, BaiduScholar, and others. Then, we analyzed the possible molecular mechanisms for different types of natural compounds in the treatment of atherosclerosis via the protection of vascular endothelial cells from oxidative stress. In addition, perspectives for possible future studies are discussed. These agents with protective effects against oxidative stress in ECs mainly include phenylpropanoids, flavonoids, terpenoids, and alkaloids. Most of these agents alleviate cell apoptosis in ECs due to oxidative stress, and the mechanisms are related to Nrf2/HO-1 signaling activation. However, despite continued progress in research on various aspects of natural agents exerting protective effects against EC injury by activating Nrf2/HO-1 signaling, the development of new drugs for the treatment of atherosclerosis (AS) and other CVDs based on these agents will require more detailed preclinical and clinical studies. Our present paper provides updated information of natural agents with protective activities on ECs against oxidative stress by activating Nrf2/HO-1. We hope this review will provide some directions for the further development of novel candidate drugs from natural agents for the treatment of AS and other CVDs.

Zhang Q ，Liu J ，Duan H ，Li R ，Peng W ，Wu C ... -  《-》

Antrodia salmonea inhibits TNF-α-induced angiogenesis and atherogenesis in human endothelial cells through the down-regulation of NF-κB and up-regulation of Nrf2 signaling pathways.

Antrodia salmonea (AS) is known as a traditional Chinese medicine, but very few biological activities have been reported. The present study was aimed to investigate the anti-angiogenic and anti-atherosclerotic potential of the fermented culture broth of AS against tumor necrosis factor-α (TNF-α)-stimulated human endothelial (EA.hy 926) cells. The non-cytotoxic concentrations of AS significantly inhibited TNF-α-induced migration/invasion and capillary-like tube formation in EA.hy 926 cells. Furthermore, AS suppressed TNF-α-induced activity and expression of matrix metalloproteinase-9 (MMP-9), and cell-surface expression of intercellular adhesion molecule-1 (ICAM-1), which was associated with abridged adhesion of U937 leukocytes to endothelial cells. Moreover, AS significantly down-regulated TNF-α-induced nuclear translocation and transcriptional activation of nuclear factor κB (NF-κB) followed by suppression of I-κB degradation and phosphorylation of I-κB kinase-α (IKKα). Notably, the protective effect of AS was directly correlated with the increased expression of hemeoxygenase-1 (HO-1) and γ-glutamylcysteine synthetase (γ-GCLC), which was reasoned by nuclear translocation and transactivation of NF-E2 related factor-2 (Nrf2)/antioxidant response element (ARE). Furthermore, HO-1 knockdown by HO-1-specific shRNA diminished the protective effects of AS on TNF-α-stimulated invasion, tube formation, and U937 adhesion in EA.hy 926 cells. Taken together, these results suggest that Antrodia salmonea may be useful for the prevention of angiogenesis and atherosclerosis.

Yang HL ，Chang HC ，Lin SW ，Senthil Kumar KJ ，Liao CH ，Wang HM ，Lin KY ，Hseu YC ... -  《-》