oxLDL-induced Injury Research Articles

LINC00452 overexpression reverses oxLDL-induced injury of human umbilical vein endothelial cells (HUVECs) via regulating miR-194-5p/IGF1R axis.

It has been reported that atherosclerosis (AS) is the basis of the development of coronary artery disease (CAD). In addition, a previous study demonstrated that long non-coding RNA LINC00452 was notably downregulated in the whole blood of patients with CAD. However, the role of LINC00452 in the progression of AS remains unclear. Therefore, to mimic AS in vitro, HUVECs were treated with 100 μg/ml oxLDL for 24 h. Reverse transcription-quantitative PCR was performed to detect the expression levels of LINC00452 and IGF1R in HUVECs. Additionally, the cell angiogenetic ability was assessed by tube formation assay, while dual-luciferase reporter assay was carried out to explore the association among LINC00452, miR-194-5p, and IGF1R. The results showed that LINC00452 was downregulated in oxLDL-treated HUVECs. In addition, HUVEC treatment with oxLDL significantly inhibited cell viability, proliferation, and angiogenesis. However, the above effects were all reversed by LINC00452 overexpression. Furthermore, LINC00452 overexpression in HUVECs remarkably inhibited oxLDL-induced cell apoptosis and endothelial to mesenchymal transition. In addition, LINC00452 overexpression could markedly reverse oxLDL-induced inhibition of angiogenesis in HUVEC. The results of dual-luciferase reporter assay indicated that LINC00452 could bind with miR-194-5p. In addition, IGF1R was identified as a downstream target of miR-194-5p. And LINC00452 was able to regulate the miR-194-5p/IGF1R axis in HUVECs. Moreover, LINC00452 overexpression obviously reversed oxLDL-mediated growth inhibition of HUVEC via regulating the miR-194-5p/IGF1R axis. Overall, the current study demonstrated that LINC00452 overexpression reversed oxLDL-induced growth inhibition of HUVECs via regulating the miR-194-5p/IGF1R axis, thus providing a potential beneficial targets for AS.

Design, synthesis and biological evaluation of marine phidianidine-inspired derivatives against oxidized ldl-induced endothelial injury by activating Nrf2 anti-oxidation pathway

Inhibition of oxidized low-density lipoprotein (oxLDL)-induced vascular endothelial cell (VEC) injury is one of the effective strategies for treating atherosclerosis. In the present study, a series of novel marine phidianidine-inspired indole-1,2,4-oxadiazoles was designed, synthesized, and evaluated for their effects against oxLDL-induced injury in VECs. Among them, compound D-6, displaying the most effective protective activity, was found to inhibit oxLDL-induced apoptosis and the expression of ICAM-1 and VCAM-1 in VECs. Mechanistic studies showed that D-6 could trigger Nrf2 nuclear translocation, subsequently resulting in increased expression of Nrf2 target gene HO-1. Meanwhile, D-6 suppressed the increase of ROS level and nuclear translocation of NF-κB induced by oxLDL. Importantly, Nrf2 knockdown attenuated the inhibition effects of D-6 on oxLDL-induced apoptosis, ROS production and NF-κB nuclear translocation. Collectively, our studies demonstrated that compound D-6 protected against oxLDL-induced endothelial injury by activating Nrf2/HO-1 anti-oxidation pathway.

Effect of total flavones of Clematis filamentosa Dunn on the oxLDL-induced injury of vascular smooth muscle cells by regulating miR-455-5p

This experiment was conducted to investigate whether total flavones of Clematis filamentosa Dunn affect the inflammatory response and apoptosis of vascular smooth muscle cells induced by oxidized low-density lipoprotein (oxLDL) by regulating microRNA-455-5p (miR-455-5p). 50 mg/mL oxLDL was performed to stimulate the injury of vascular smooth muscle cells, and the total flavones of Clematis filamentosa Dunn were added at concentrations of 75, 150, and 300 μg/mL. The expressions of inflammatory factors IL-1β and TNF-α were analyzed by ELISA, the apoptosis was evaluated by flow cytometry, the expression of Bcl-2 and Bax was determined by western blot, and the real-time fluorescence quantitative PCR (qRT-PCR) was applied to detect miR-455-5p expression. MiR-455-5p mimic was transfected into vascular smooth muscle cells and then induced injury with oxLDL; miR-455-5p inhibitor was transfected into vascular smooth muscle cells and treated with oxLDL and 300 μg/mL total flavones of Clematis filamentosa Dunn. The above methods were employed to investigate the inflammatory response and apoptosis of cells. The total flavones of Clematis filamentosa Dunn significantly inhibited the expression of IL-1β, TNF-α, apoptosis rate, Bax protein expression of oxLDL induced vascular smooth muscle cells, and remarkably promoted the expression of Bcl-2 protein and miR-455-5p, which all showed concentration dependence (p<0.05). Overexpression of miR-455-5p reduced IL-1β, TNF-α expression, apoptosis rate, Bax protein expression, and greatly increased Bcl-2 protein expression in oxLDL injured vascular smooth muscle cells (p<0.05). After interfering with the expression of miR-455-5p, the inhibitory effect of total flavones of Clematis filamentosa Dunn on the expression of IL-1β, TNF-α, apoptosis, Bax protein expression of oxLDL-induced vascular smooth muscle cells was reversed, and its promotion effect on Bcl-2 protein expression was also reversed. Total flavones of Clematis filamentosa Dunn can reduce oxLDL-induced vascular smooth muscle cell inflammation and inhibit its apoptosis. The mechanism of action is related to the up-regulation of miR-455-5p expression.

Oxidized LDL triggers changes in oxidative stress and inflammatory biomarkers in human macrophages

Oxidized low-density lipoprotein (oxLDL) is a well-recognized proatherogenic particle that functions in atherosclerosis. In this study, we established conditions to generate human oxLDL, characterized according to the grade of lipid and protein oxidation, particle size and oxylipin content. The induction effect of the cellular proatherogenic response was assessed in foam cells by using an oxLDL-macrophage interaction model. Uptake of oxLDL, reactive oxygen species production and expression of oxLDL receptors (CD36, SR-A and LOX-1) were significantly increased in THP-1 macrophages. Analyses of 35 oxylipins revealed that isoprostanes (IsoP) and prostaglandins (PGs) derived from the oxidation of arachidonic, dihomo gamma-linolenic and eicosapentaenoic acids were strongly and significantly induced in macrophages stimulated with oxLDL. Importantly, the main metabolites responsible for the THP1-macrophage response to oxLDL exposure were the oxidative stress markers 5-epi-5-F2t-IsoP, 15-E1t-IsoP, 8-F3t-IsoP and 15-keto-15-F2t-IsoP as well as inflammatory markers PGDM, 17-trans-PGF3α, and 11β-PGF2α, all of which are reported here, for the first time, to function in the interaction of oxLDL with THP-1 macrophages. By contrast, a salvage pathway mediated by anti-inflammatory PGs (PGE1 and 17-trans-PGF3α) was also identified, suggesting a response to oxLDL-induced injury. In conclusion, when THP-1 macrophages were treated with oxLDL, a specific induction of biomarkers related to oxidative stress and inflammation was triggered. This work contributes to our understanding of initial atherogenic events mediated by oxLDL-macrophage interactions and helps to generate new approaches for their modulation.

Dihydromyricetin Ameliorates Atherosclerosis in LDL Receptor Deficient Mice

Abstract Background and aims Dihydromyricetin, the most abundant flavonoid in Ampelopsis grossedentata , exerts numerous pharmacological activities, including anti-inflammatory, antioxidant, hepatoprotective, and lipid regulatory activities; however, its protective effect against atherosclerosis remains poorly understood. The aim of the present study was to evaluate the effects of dihydromyricetin on high fat diet (HFD)-induced atherosclerosis using LDL receptor deficient ( LDLr −/− ) mice. Methods Blood samples were collected for determination of serum lipid profiles, oxidized LDL (ox-LDL) and pro-inflammatory cytokines. Histology, hepatic lipid content, quantification of atherosclerosis, assessment of oxidative stress and inflammation were performed on liver and aorta samples by molecular biology methods. The effects of dihydromyricetin on ox-LDL-induced human umbilical vein endothelial cells (HUVECs) dysfunction and foam cell formation were further studied. Results (1) Dihydromyricetin ameliorated hyperlipidemia, reduced serum ox-LDL, IL-6 and TNF-α levels in HFD-fed LDLr −/- mice. Moreover, (2) dihydromyricetin suppressed hepatic lipid accumulation and increased protein expressions of PPARα, LXRα and ABCA1. (3) It inhibited atherosclerotic lesion formation and favoured features of plaque stability. (4) Dihydromyricetin prevented hepatic and aortic inflammation as evidenced by the reduced IL-6 and TNF-α mRNA expression; (5) it prevented hepatic and aortic oxidative stress by normalizing activities of antioxidant enzymes in the liver and suppressing reactive oxygen species generation and NOX2 protein expression in both liver and aorta; (6) it inhibited oxLDL-induced injury, monocytes adhesion and oxidative stress in HUVECs and (7) inhibited macrophage foam cell formation and enhanced cholesterol efflux. Conclusions These findings suggest that dihydromyricetin could reduce atherosclerosis via its pleiotropic effects, including improvement of endothelial dysfunction, inhibition of macrophage foam cell formation, amelioration of lipid profiles, anti-inflammatory action and anti-oxidative effect.

Dihydromyricetin ameliorates atherosclerosis in LDL receptor deficient mice

Background and aimsDihydromyricetin, the most abundant flavonoid in Ampelopsis grossedentata, exerts numerous pharmacological activities, including anti-inflammatory, antioxidant, hepatoprotective, and lipid regulatory activities; however, its protective effect against atherosclerosis remains poorly understood. The aim of the present study was to evaluate the effects of dihydromyricetin on high fat diet (HFD)-induced atherosclerosis using LDL receptor deficient (LDLr−/−) mice. MethodsBlood samples were collected for determination of serum lipid profiles, oxidized LDL (ox-LDL) and pro-inflammatory cytokines. Histology, hepatic lipid content, quantification of atherosclerosis, assessment of oxidative stress and inflammation were performed on liver and aorta samples by molecular biology methods. The effects of dihydromyricetin on ox-LDL-induced human umbilical vein endothelial cells (HUVECs) dysfunction and foam cell formation were further studied. Results(1) Dihydromyricetin ameliorated hyperlipidemia, reduced serum ox-LDL, IL-6 and TNF-α levels in HFD-fed LDLr−/− mice. Moreover, (2) dihydromyricetin suppressed hepatic lipid accumulation and increased protein expressions of PPARα, LXRα and ABCA1. (3) It inhibited atherosclerotic lesion formation and favoured features of plaque stability. (4) Dihydromyricetin prevented hepatic and aortic inflammation as evidenced by the reduced IL-6 and TNF-α mRNA expression; (5) it prevented hepatic and aortic oxidative stress by normalizing activities of antioxidant enzymes in the liver and suppressing reactive oxygen species generation and NOX2 protein expression in both liver and aorta; (6) it inhibited oxLDL-induced injury, monocytes adhesion and oxidative stress in HUVECs and (7) inhibited macrophage foam cell formation and enhanced cholesterol efflux. ConclusionsThese findings suggest that dihydromyricetin could reduce atherosclerosis via its pleiotropic effects, including improvement of endothelial dysfunction, inhibition of macrophage foam cell formation, amelioration of lipid profiles, anti-inflammatory action and anti-oxidative effect.

Delphinidin-3-glucoside protects human umbilical vein endothelial cells against oxidized low-density lipoprotein-induced injury by autophagy upregulation via the AMPK/SIRT1 signaling pathway.

Oxidized LDL (oxLDL) induced vascular endothelial cell injury is a key event in the pathogenesis of atherosclerosis (AS). In our previous studies, we showed that delphinidin-3-glucoside (Dp), a natural anthocyanin, attenuated oxLDL-induced injury in human umbilical vein endothelial cells (HUVECs), indicating its potential role in preventing AS. However, the involved mechanism is not fully understood. Via methyl thiazolyl tetrazolium and flow cytometry assay, we found that Dp-attenuated oxLDL-induced cell viability decrease and apoptosis in HUVECs. Depending on confocal microscopy, transmission electron microscopy, and Western blot assay, we found that Dp-induced autophagy in HUVECs, whereas suppression of autophagy significantly abolished the protective role of Dp against oxLDL-induced endothelial cell injury. Furthermore, Dp upregulated sirtuin 1 (SIRT1) expression and SIRT1 knockdown notably suppressed Dp-induced autophagy in HUVECs. Dp also increased the expression of phosphorylated adenosine monophosphate-activated protein kinase, while adenosine monophosphate-activated protein kinase (AMPK) knockdown remarkably abolished Dp-induced SIRT1 expression and subsequent autophagy. Our data suggested that Dp protected HUVECs against oxLDL-induced injury by inducing autophagy via the adenosine monophosphate-activated protein kinase/SIRT1 signaling pathway. This new finding might shed light to the prevention and therapy of AS.

Taurine protects HK-2 cells from oxidized LDL-induced cytotoxicity via the ROS-mediated mitochondrial and p53-related apoptotic pathways

Oxidized LDL (oxLDL) induces a pro-oxidative environment and promotes apoptosis, causing the progression of renal diseases in humans. Taurine is a semi-essential amino acid in mammals and has been shown to be a potent endogenous antioxidant. The kidney plays a pivotal role in maintaining the balance of taurine. However, the mechanisms underlying the protective effects of taurine against oxLDL-induced injury in renal epithelial cells have not been clarified. In the present study, we investigated the anti-apoptotic effects of taurine on human proximal tubular epithelial (HK-2) cells exposed to oxLDL and explored the related mechanisms. We observed that oxLDL increased the contents of ROS and of malondialdehyde (MDA), which is a lipid peroxidation by-product that acts as an indicator of the cellular oxidation status. In addition, oxLDL induced cell death and apoptosis in HK-2 cells. Pretreatment with taurine at 100μM significantly attenuated the oxLDL-induced cytotoxicity. We determined that oxLDL triggered the phosphorylation of ERK and, in turn, the activation of p53 and other apoptosis-related events, including calcium accumulation, destabilization of the mitochondrial permeability and disruption of the balance between pro-apoptotic Bax and anti-apoptotic Bcl-2 proteins. The malfunctions induced by oxLDL were effectively blocked by taurine. Thus, our results suggested that taurine exhibits potential therapeutic activity by preventing oxLDL-induced nephrotoxicity. The inhibition of oxLDL-induced epithelial apoptosis by taurine was at least partially due to its anti-oxidant activity and its ability to modulate the ERK and p53 apoptotic pathways.

LOX-1-mediated injury in sensory neurons in type 2 diabetes

Our laboratory recently identified several differentially expressed genes (DEG) through microarray analysis of the sciatic nerves of 24-week-old BKS db/db (diabetic) and db/+ (nondiabetic) mice. We noted prominent increases in lipid metabolism genes, consistent with another model, the high fat-fed C57BL6/J mouse, where we postulated that oxidized low-density lipoproteins (oxLDL) activate a receptor-mediated inflammatory pathway of neuronal injury. Our findings support clinical observations that plasma lipids associate with neuropathy, and suggest that glucose and lipids together will be responsible for the most aggressive development of diabetic neuropathy. A role for oxLDL-induced injury remains to be proved in vivo, and this is the goal of the present study. First, we performed biostatistical network analysis to identify molecular interactions of our LOX-1 gene of interest, Olr1. Next, nondiabetic BKSdb/+ and diabetic BKSdb/db littermates received intraperitoneal injections of LOX-1 neutralizing antibody or control non-immune IgG every 48 h from 6-12 wk of age. At 12 wk of age, blood and tissues were harvested for metabolic and neuropathy phenotyping. We confirmed our network analysis by demonstrating that NFkappaB, a gene closely linked to Olr1 in our network, was decreased in anti-LOX-1 treated mice. Most metabolic parameters (blood glucose, glycated hemoglobin, plasma triglycerides and cholesterol) and also the sciatic motor nerve conduction velocity deficit were unchanged in the presence of anti-LOX-1 treatment compared with control IgG. However, there was a striking preservation of the sural nerve conduction velocity in anti-LOX-1-treated mice, demonstrating that this receptor is involved in sural nerve injury in type 2 diabetes.

Ellagic acid protects endothelial cells from oxidized low-density lipoprotein-induced apoptosis by modulating the PI3K/Akt/eNOS pathway

Endothelial apoptosis is a driving force in atherosclerosis development. Oxidized low-density lipoprotein (oxLDL) promotes inflammatory and thrombotic processes and is highly atherogenic, as it stimulates macrophage cholesterol accumulation and foam cell formation. Previous studies have shown that the phosphatidylinositol 3-kinase/Akt/endothelial nitric oxide synthase/nitric oxide (PI3K/Akt/eNOS/NO) pathway is involved in oxLDL-induced endothelial apoptosis. Ellagic acid, a natural polyphenol found in berries and nuts, has in recent years been the subject of intense research within the fields of cancer and inflammation. However, its protective effects against oxLDL-induced injury in vascular endothelial cells have not been clarified. In the present study, we investigated the anti-apoptotic effect of ellagic acid in human umbilical vein endothelial cells (HUVECs) exposed to oxLDL and explored the possible mechanisms. Our results showed that pretreatment with ellagic acid (5–20 μM) significantly attenuated oxLDL-induced cytotoxicity, apoptotic features, and generation of reactive oxygen species (ROS). In addition, the anti-apoptotic effect of ellagic acid was partially inhibited by a PI3K inhibitor (wortmannin) and a specific eNOS inhibitor (cavtratin) but not by an ERK inhibitor (PD98059). In exploring the underlying mechanisms of ellagic acid action, we found that oxLDL decreased Akt and eNOS phosphorylation, which in turn activated NF-κB and downstream pro-apoptotic signaling events including calcium accumulation, destabilization of mitochondrial permeability, and disruption of the balance between pro- and anti-apoptotic Bcl-2 proteins. Those alterations induced by oxLDL, however, were attenuated by pretreatment with ellagic acid. The inhibition of oxLDL-induced endothelial apoptosis by ellagic acid is due at least in part to its anti-oxidant activity and its ability to modulate the PI3K/Akt/eNOS signaling pathway.

Crude extracts of Solanum lyratum protect endothelial cells against oxidized low-density lipoprotein-induced injury by direct antioxidant action

Oxidized low-density lipoprotein (oxLDL) is a proatherogenic molecule that accumulates in the vascular wall and contributes to the pathogenesis of vascular dysfunction early in the development of atherosclerosis. The whole plant of Solanum lyratum is a traditional Chinese medicine that has been used for centuries to treat cancer, tumors, and herpes. However, the cellular and molecular mechanisms of its antioxidant effects are still largely unknown. This study tested the hypothesis that Solanum lyratum Thunberg extract (SLE) could block oxLDL-induced endothelial dysfunction in cultured human umbilical vein endothelial cells (HUVECs). Possible mechanisms were explored. Antioxidative activities of SLE were assayed by measuring the scavenging of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical and the inhibition of copper-mediated or cell-mediated LDL oxidation. Production of reactive oxygen species (ROS) and the expression of adhesion molecules were evaluated in HUVECs after exposure to oxLDL and treatment with SLE. Several apoptotic signaling pathways were investigated. SLE scavenged DPPH and also delayed the kinetics of LDL oxidation in a dose-dependent manner. SLE attenuated the level of oxLDL-induced ROS generation, diminished the expression of endothelial NO synthase (eNOS), and enhanced the expression of adhesion molecules (vascular cellular adhesion molecule-1, E-selectin, and monocyte chemotactic protein-1) and the adherence of monocytic THP-1 cells to HUVECs. OxLDL increased the concentration of intracellular calcium, disturbed the balance of the Bcl-2 protein family, destabilized the mitochondrial membrane potential, increased the amount of cytochrome c released into the cytosol, and increased the activation of caspase 3. These detrimental effects were ameliorated dose-dependently by SLE (P < .05). Crude extracts of Solanum lyratum protect against oxLDL-induced injury in endothelial cells by direct antioxidant action. Atherosclerosis is a chronic inflammatory disease characterized by lipid-laden lesions within arterialblood vessel walls. Inhibiting the oxidation of low-density lipoprotein may be an effective way to prevent or delay theprogression of atherosclerosis. This study underscores the potential clinical benefits and application of Solanum lyratumextract in controlling oxidized low-density lipoprotein-associated vascular injury and cardiovascular disease.