Cytoprotective effects of euxanthone against ox-LDL-induced endothelial cell injury is mediated via Nrf2.

Atherosclerosis (AS) is a chronic condition of the arterial vessels and a risk factor for myocardial infarction and stroke. Euxanthone is a xanthone compound extracted from Polygala caudata, and shows vasodilatory action. The aim of this study was to determine the potential pharmacological effects of euxanthone against oxidized low-density lipoprotein (ox-LDL)-induced endothelial cell injury. Human umbilical vein endothelial cells (HUVECs) were exposed to ox-LDL, following pre-treatment with different concentrations of euxanthone. Viability, apoptosis and DNA fragmentation were respectively assessed by CCK-8 assay, Annexin-V/PI staining and TdT-mediated dUTP Nick-End Labeling (TUNEL) assay. The cellular levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were analyzed by enzyme linked immune-sorbent assays (ELISA), and reactive oxygen species (ROS) levels using dichlorodihydrofluorescin diacetate (DCFH) staining. Quantitative RT-PCR and Western blotting were respectively used to analyze the expression levels of specific mRNAs and proteins. HUVECs were transfected with Nrf2 siRNA to induce knockdown of the latter. Euxanthone pre-treatment rescued the HUVECs from ox-LDL-induced cytotoxicity, apoptosis and DNA fragmentation in a dose-dependent manner. In addition, euxanthone also significantly reversed ox-LDL-triggered loss of mitochondrial membrane potential (MMP), cytochrome C release from mitochondria to cytosol, cleavage of caspase-3 and PARP, and increase in Bax/Bcl-2 ratio. Pre-treatment with euxanthone markedly suppressed ox-LDL-induced ROS generation and inhibition of antioxidant enzymes, as well as the up-regulation of pro-inflammatory factors like MCP-1, IL-1β and TNF-α in the HUVECs. Euxanthone up-regulated and activated Nrf2 by repressing Keap1, and increased the expression of its downstream genes HO-1 and NQO-1. Nrf2 knockdown abrogated the cyto-protective, anti-apoptotic, anti-oxidant and anti-inflammatory effects of euxanthone in ox-LDL-treated HUVECs. Finally, euxanthone activated Nrf2 via the MAPK pathway and blocking the latter likewise negated the protective effects of euxanthone against cell ox-LDL. Euxanthone protected HUVECs against the oxidative and inflammatory damage induced by ox-LDL, indicating its potential as a novel therapeutic agent for AS.

Li S ，Sun Y ，Han Z ，Bu X ，Yu W ，Wang J ... -  《-》

Xanthoangelol Prevents Ox-LDL-Induced Endothelial Cell Injury by Activating Nrf2/ARE Signaling.

Yan R ，Yan J ，Chen X ，Yu Y ，Sun T ... -  《-》

Zedoarondiol Attenuates Endothelial Cells Injury Induced by Oxidized Low-Density Lipoprotein via Nrf2 Activation.

Zedoarondiol, a sesquiterpene lactone compound, showed an anti-proliferative activity on vascular smooth muscle cells in our previous study. However, whether it has a beneficial effect on endothelial cells injury induced by oxidized low-density lipoprotein (ox-LDL) remains unclear. This study was designed to investigate the protective effect of zedoarondiol on ox-LDL-induced injury of endothelial cells and explored its underlying mechanism. The protective effect of zedoarondiol on ox-LDL-induced human umbilical vein endothelial cells (HUVECs) injury were evaluated by Cell Counting Kit-8 (CCK-8) assay and released lactic dehydrogenase (LDH) activity assay. Oxidative stress was determined by malonedialdehyde (MDA) content and superoxide dismutase (SOD) activity. The level of reactive oxygen species (ROS) was measured by dichlorodihydrofluorescin diacetate (DCFH-DA) staining. The culture supernatant was collected for enzyme linked immune-sorbent assays (ELISA) of interleukine-1β (IL-1β), tumor necrosis factor-α (TNF-α), and monocyte chemoattractant protein-1 (MCP-1). Immunofluorescence staining was used to observe NF-E2-related factor 2 (Nrf2) translocation. Western blotting was performed to determine the expression of IL-1β, TNF-α, MCP-1, Kelch-like ECH associated protein 1 (Keap1), heme oxygenase-1 (HO-1), NAD(P)H: quinone oxidoreductase-1 (NQO1), and Nrf2. Zedoarondiol attenuated HUVECs injury, up-regulated SOD activity, suppressed formation of MDA and ROS, and secretion and protein expression of IL-1β, TNF-α, and MCP-1 in injured HUVECs induced by ox-LDL. Zedoarondiol induced nuclear Nrf2 translocation from cytoplasm into nucleus and up-regulated expression of HO-1, NQO1, and Nrf2 in nucleus. All-trans-retinoic acid (ATRA), an inhibitor of Nrf2, abolished zedoarondiol-mediated anti-oxidative effect. Zedoarondiol attenuates ox-LDL-induced endothelial cells injury by inhibiting oxidative stress and inflammation via Nrf2/HO-1 pathway, suggesting that zedoarondiol might be meaningful on prevention and treatment of atherosclerosis.

Mao H ，Tao T ，Wang X ，Liu M ，Song D ，Liu X ，Shi D ... -  《-》

Dihydromyricetin protects human umbilical vein endothelial cells from injury through ERK and Akt mediated Nrf2/HO-1 signaling pathway.

Luo Y ，Lu S ，Dong X ，Xu L ，Sun G ，Sun X ... -  《-》

Procyanidin B2 alleviates oxidized low-density lipoprotein-induced cell injury, inflammation, monocyte chemotaxis, and oxidative stress by inhibiting the nuclear factor kappa-B pathway in human umbilical vein endothelial cells.

Oxidized low-density lipoprotein (ox-LDL) can initiate and affect almost all atherosclerotic events including endothelial dysfunction. In this text, the role and underlying molecular basis of procyanidin B2 (PCB2) with potential anti-oxidant and anti-inflammatory activities in ox-LDL-induced HUVEC injury were examined. HUVECs were treated with ox-LDL in the presence or absence of PCB2. Cell viability and apoptotic rate were examined by CCK-8 assay and flow cytometry, respectively. The mRNA and protein levels of genes were tested by RT-qPCR and western blot assays, respectively. Potential downstream targets and pathways of apple procyanidin oligomers were examined by bioinformatics analysis for the GSE9647 dataset. The effect of PCB2 on THP-1 cell migration was examined by recruitment assay. The effect of PCB2 on oxidative stress was assessed by reactive oxygen species (ROS) level, malondialdehyde (MDA) content, and mitochondrial membrane potential (MMP). ox-LDL reduced cell viability, induced cell apoptosis, and facilitated the expression of oxidized low-density lipoprotein receptor 1 (LOX-1), C-C motif chemokine ligand 2 (MCP-1), vascular cell adhesion protein 1 (VCAM-1) in HUVECs. PCB2 alleviated ox-LDL-induced cell injury in HUVECs. Apple procyanidin oligomers triggered the differential expression of 592 genes in HUVECs (|log2fold-change| > 0.58 and adjusted p-value < 0.05). These dysregulated genes might be implicated in apoptosis, endothelial cell proliferation, inflammation, and monocyte chemotaxis. PCB2 inhibited C-X-C motif chemokine ligand 1/8 (CXCL1/8) expression and THP-1 cell recruitment in ox-LDL-stimulated HUVECs. PCB2 inhibited ox-LDL-induced oxidative stress and nuclear factor kappa-B (NF-κB) activation in HUVECs. PCB2 weakened ox-LDL-induced cell injury, inflammation, monocyte recruitment, and oxidative stress by inhibiting the NF-κB pathway in HUVECs.

Yuan L ，Fan L ，Zhang Z ，Huang X ，Liu Q ，Zhang Z ... -  《BMC Cardiovascular Disorders》