Apoptosis In Aortic Endothelial Cells Research Articles

Cyclin-dependent kinase 5 contributes to apoptosis of vascular endothelial cells during aortic dissection.

BackgroundTearing of inner layer of aorta causes aortic dissection (AD), a severe disease with high morbidity and mortality. The pathological development of AD partially results from apoptotic death of aortic endothelial cells (AECs), the trigger and the molecular regulation of which remain largely unknown. Cyclin-dependent kinase 5 (CDK5) was initially detected in the brain as a proline-directed serine/threonine protein kinase regulating neuronal cell cycle re-entry and arrest. The abnormal expression of CDK5 leads to apoptotic cell death following abortive cell cycle re-entry in some neuronal diseases. Although physiological and pathological roles of CDK5 have been widely investigated, the expression and function of CDK5 in AD have not been reported. Therefore, the aim of the present study was to discuss the expression and function of CDK5 in AD.MethodsGene expression profiles were compared between AD tissues and normal aortic tissues using Gene Expression Omnibus (GEO) database with bioinformatic tools. Different cell types were isolated from the digested AD and normal aortic specimens by fluorescence-activated cell sorting (FACS). Gene expression in cells was quantified by quantitative reverse transcription polymerase chain reaction. Endothelial cells purified by FACS were transfected in vivo with plasmids. Cell growth was analyzed by Cell Counting Kit-8 assay. Cell apoptosis was analyzed by terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick-end labeling assay.ResultsAnalysis of gene profiles from AD tissues and normal aortic tissues using GEO database showed significant higher expression of CDK5 and its downstream regulated genes, proliferating cell nuclear antigen, cyclin B1, and B-cell lymphoma 2, which are regulators for cell cycle and apoptosis. Analysis of purified cells from AD and normal aortic specimens further confirmed this result and showed that the major source of CDK5 was endothelial cells. Depletion of CDK5 inhibited apoptosis of AECs, while the expression of CDK5 promoted apoptosis of AECs.ConclusionsCDK5 induces apoptosis of AECs to promote AD. CDK5 appears to be a promising novel target for preventing AD.

MiR-137 regulates low-intensity shear stress-induced human aortic endothelial cell apoptosis via JNK/AP-1 signaling.

The objective of this study is to evaluate the role of miR-137 in low-intensity shear stress-induced endoplasmic reticulum (ER) stress and cell apoptosis in human aortic endothelial cells (HAECs). HAECs were transfected with miR-137 mimic, miR-137 inhibitor, or the corresponding negative control and then exposed to pulsatile shear stress in a parallel-plate flow chamber at 1, 2, 5, 10, and 15 dyn/cm2 for 3 h. Real-time polymerase chain reaction was used to detect mRNA expression of miR-137 and SDS22. A dual-luciferase reporter assay was employed to verify the direct interaction between miR-137 and SDS22. The internal morphology of cells and cell apoptosis was assessed by TUNEL staining observed under a transmission electron microscope. Meanwhile, the protein expression of oxidative stress-related, apoptosis-related, and activated c-Jun N-terminal kinase (JNK)/activator protein-1 (AP-1) signaling-related genes were analyzed by western blotting. Low strength shear stress (0-5 dyn/cm2) caused a negative change of HAEC surface and internal morphology in an intensity-dependent manner, and these changes were gradually weakened when shear stress was increased more than 5 dyn/cm2. Furthermore, low-intensity shear stress promoted oxidative stress response, accelerated cell apoptosis, and upregulated miR-137 expression and JNK/AP-1 signaling in HAECs. MiR-137 directly targets SDS22. Knockdown of miR-137 noticeably reduced activation of JNK/AP-1 signaling, oxidative stress response, and cell apoptosis induced by shear stress. MiR-137 regulated low-intensity shear stress-induced human aortic endothelial cell ER stress and cell apoptosis via JNK/AP-1 signaling.

Decreased expression of PPARγ is associated with aortic endothelial cell apoptosis in intermittently hypoxic rats.

Increasing medical researche shows that endothelial dysfunction is one of the important causes of various cardiovascular diseases related to chronic intermittent hypoxia (CIH). This study aimed to identify target proteins in CIH-related vascular dysfunction. A comparative proteomics analysis was conducted in aortic samples of rats treated with CIH and controls with normoxia. Bioinformatics analyses were performed to determine the potential roles of major proteins. The expressions of target proteins were measured by western blotting. Cell apoptotic ratio was detected by flow cytometer. A total of 3,593 proteins in aortic tissues of rats were quantified. Ninety-two upregulated proteins and 468 downregulated proteins were identified when the cutoff of fold change was set at 1.5 (CIH vs. normoxia). The results of bioinformatics analysis revealed that the differentially expressed proteins were enriched in the processes of energy metabolism and lipid metabolism. The reduced expression level of peroxisome proliferator-activated receptor γ (PPARγ) protein was identified in thoracic aortic tissues of rats with CIH by proteomics analysis and western blotting. In intermittent hypoxia-treated rat aortic endothelial cells, PPARγ protein levels were reduced, and the apoptosis rate and caspase-3 and Bax protein levels were markedly elevated. Importantly, forced expression of PPARγ by rosiglitazone in intermittent hypoxia-treated rat aortic endothelial cells not only attenuated caspase-3 and Bax protein levels but also reduced the rate of apoptosis. PPARγ is critical in endothelial dysfunction of rats with CIH. Additional studies on these differentially expressed proteins associated with CIH-related endothelial dysfunction are necessary.

Silencing of the long non-coding RNA MEG3 suppresses the apoptosis of aortic endothelial cells in mice with chronic intermittent hypoxia via downregulation of HIF-1α by competitively binding to microRNA-135a.

BackgroundChronic intermittent hypoxia (CIH) involves substantial cortico-hippocampal injury, causing impairments of neurocognitive, respiratory, and cardiovascular functions. Long non-coding RNAs (lncRNAs) participate in CIH functions and development. Therefore, we explored the mechanisms involving lncRNA maternally expressed gene 3 (MEG3) regulating the aortic endothelial function of CIH mice via regulation of microRNA-135a (miR-135a) and the hypoxia-inducible factor (HIF)-1α.MethodsExpression of MEG3, miR-135a, and HIF-1α in CIH mice and CIH-treated cells was detected. Then, the apoptosis and proliferation of the aortic endothelial cells were examined to verify whether miR-135a and HIF-1α participated in CIH. Next, the interactions between MEG3, miR-135a, and HIF-1α were explored. Later, the effects of MEG3/miR-135a/HIF-1α on the expression of proliferation- and apoptosis-related factors and aortic injury were investigated via gain- and loss-of function studies both in vivo and in vitro.ResultsMEG3 and HIF-1α were highly expressed while miR-135a was poorly expressed in CIH mice and CIH-modeled cells. Moreover, miR-135a targeted HIF-1α to promote cell proliferation and inhibit apoptosis. MEG3 regulated HIF-1α expression by competitively binding to miR-135a. More importantly, we found that the silencing of MEG3/HIF-1α and the overexpression of miR-135a inhibited the apoptosis and injury of aortic endothelial cells while promoting cell proliferation in CIH mice.ConclusionsAltogether, silencing of MEG3 suppressed the aortic endothelial injury and cell apoptosis in CIH mice by downregulating HIF-1α through sponging miR-135a, providing evidence of a potential therapeutic target for CIH.

Pigment epithelium-derived factor (PEDF) ameliorates arsenic-induced vascular endothelial dysfunction in rats and toxicity in endothelial EA.hy926 cells

Although the harmful effects of arsenic exposure on the cardiovascular system have received great attention, there is still no effective treatment. Vascular endothelial dysfunction (VED) is the initial step of cardiovascular diseases, where pigment epithelium-derived factor (PEDF) plays an important role in maintaining endothelial function. Here, we explored the protective role of PEDF in VED induced by arsenic, and its underlying molecular mechanism, designing an in vivo rat model of arsenic exposure recovery and in vitro endothelial EA. hy926 cell-based assays. The edema of aortic endothelial cells in rats significantly improved during recovery from arsenite exposure compared with rats exposed to 10 and 50 mg/L arsenite continuously. In addition, serum levels of nitric oxide (NO), von Willebrand factor, and nitric oxide synthase (inducible and total activities) in rats, which were greatly affected by arsenite exposure, returned to levels similar to those in the control group after recovery with distilled water. The recovery from arsenite exposure was associated with increased levels of PEDF; decreased protein levels of Fas, FasL, P53, and phospho-p38; and inhibited apoptosis in aortic endothelial cells in vivo. Recombinant human PEDF treatment (100 nM) prevented the toxic effects of arsenite (50 μM) on endothelial cells in vitro by increasing NO content, decreasing reactive oxygen species (ROS) levels, and inhibiting apoptosis, as well as increasing cell viability and decreasing levels of P53 and phospho-p38. Our findings suggest that PEDF protects endothelial cells from arsenic-induced VED by increasing NO release and inhibiting apoptosis, where P53 and p38MAPK are its main targets.

MicroRNA-217-5p ameliorates endothelial cell apoptosis induced by ox-LDL by targeting CLIC4

Background and aimsEndothelial cell apoptosis plays an essential role in the pathogenesis of atherosclerosis. MicroRNAs and chloride intracellular channels (CLICs) have been verified to participate in the endothelial cell apoptosis process, however, the underlying molecular mechanisms are still unclear. The main aim of this study was to investigate the biological effects of microRNA-217-5p (miR-217-5p) and CLIC4 on endothelial cell apoptosis in atherosclerosis. Methods and resultsAn atherosclerotic mouse model (n = 18) was constructed by feeding apolipo protein E knockout ApoE(−/−) mice with high-fat diet for 12 weeks. An atherosclerotic cell model was established by treating human aortic endothelial cells with oxidized low-density lipoprotein (ox-LDL; 50 μg/mL) for 24 h. Quantitative real-time polymerase chain reaction and immunofluorescent staining confirmed the downregulation of miR-217-5p and upregulation of CLIC4 in atherosclerotic endothelial cells. Combined with western blot, flow cytometry assay and Hoechst staining, we demonstrated that miR-217-5p upregulation or CLIC4 knockdown regulated the apoptosis-related genes, ameliorated mitochondrial membrane permeability and therefore inhibited the apoptosis of aortic endothelial cells induced by ox-LDL. We further confirmed that miR-217-5p inhibited apoptosis of endothelial cells through targeting CLIC4 using luciferase report assay and rescue experiments. ConclusionWe revealed for the first time that miR-217-5p inhibited apoptosis of endothelial cells in atherosclerosis and identified CLIC4 as a novel target of miR-217-5p. Our work provides a potential therapeutic approach for the treatment of atherosclerosis.

Down-regulation of lncRNA MALAT1 alleviates vascular lesion and vascular remodeling of rats with hypertension.

Objective: Recently, the effect of long non-coding RNAs (lncRNAs) in hypertension (HTN) has been identified. This study aims to explore the expression of lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in HTN and its role in vascular lesion and remodeling of HTN rats.Results: LncRNA MALAT1 expression was up-regulated in HTN patients, and lncRNA MALAT1 could be an effective index of HTN diagnosis. Down-regulated MALAT1 and inhibited Notch-1 could reduce relative factor expression, including inflammation-related factors, endothelial function-related factors and oxidative stress-related factors, and inhibit apoptosis of aortic endothelial cells of HTN rats.Methods: LncRNA MALAT1 expression in HTN patients and healthy controls was detected by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Angiotensin II (Ang II)-induced HTN rat models were injected with MALAT1-siRNA, empty lentivirus vector, Notch pathway inhibitor (DAPT) and dimethyl sulphoxide (DMSO) via caudal vein. After three-week treatment, changes of blood pressure, inflammatory factor levels, endothelial function-related factors, oxidative stress indices and apoptosis of vascular endothelial cells were determined by a series of assays.Conclusion: This study revealed that down-regulated lncRNA MALAT1 could alleviate the vascular lesion and remodeling of HTN rats, the mechanism may be related to the inhibited activation of Notch signaling pathway.

Effects of Taurine on Broiler Aortic Endothelial Apoptosis Induced by Heat Stress.

Heat stress is an environmental factor that causes severe economic loss to the current intensive breeding industry and induces huge impact on the long-term growth in livestock and poultry industry. Many animal experiments confirmed that heat stress is a major cause of heat stroke death, which is due to severe damage to endothelial cells. In order to provide a theoretical basis for the treatment or mitigation of heat stress related diseases in broilers, the effect of taurine on injury and apoptosis of aortic endothelial cells in broilers under heat stress was investigated in the present study. Ten days healthy broilers were sacrificed, then aortic tissue was used to isolate and cultivate primary broiler aortic endothelial cells. The third to the fifth generations of cells were used in the experiment. The cells were randomly divided into five groups, including control group (C), heat stress group (HS), low taurine (HS+LTau) group, mild taurine (HS+MTau) group and high taurine (HS+HTau) group. Cells in all groups were cultivated for 24h in cell incubator (37°C, 5% CO2). Then the heat stress group cells were cultivated in a 43°C thermostatic water bath for 6h under heat stress, and then re-incubated under 37°C for 1h. The results showed that compared with the control group, expression levels of Bax, Caspase-9, Caspase-3, Cyt-c, P53 and other pro-apoptosis factors in HS groups were significantly increased (P<0.05), while expression levels of anti-apoptosis factor Bcl-2 showed a significant decrease (P<0.05). Compared with HS group, expression levels of Bcl-2 in endothelial cells were significantly increased by taurine administration (P<0.05), while expression of Bax, Caspase-9, Caspase-3, Cyt-c and P53 were significantly increased by taurine (P<0.05). In summary, the present data indicated that taurine could protect against injury and apoptosis of aortic endothelial cells under heat stress by inhibiting the activation of mitochondria-mediated apoptotic pathways.

Matrine‐Type Alkaloids Inhibit Advanced Glycation End Products Induced Reactive Oxygen Species‐Mediated Apoptosis of Aortic Endothelial Cells In Vivo and In Vitro by Targeting MKK3 and p38MAPK Signaling

BackgroundThe matrine‐type alkaloids are bioactive components extracted from Sophora flavescens, which is used in treatment of diabetes mellitus in traditional Chinese medicine. Advanced glycation end products mediate diabetic vascular complications. This study was aimed to investigate the protective effects and molecular mechanisms of matrine‐type alkaloids on advanced glycation end products–induced reactive oxygen species–mediated endothelial apoptosis.Methods and ResultsRats aorta and cultured rat aortic endothelial cells were exposed to advanced glycation end products. Matrine‐type alkaloids, p38 mitogen‐activated protein kinase (MAPK) inhibitor, and small interference RNAs against p38 MAPK kinases MAPK kinase kinase (MKK)3 and MKK6 were administrated. Intracellular reactive oxygen species production, cell apoptosis, phosphorylation of MKKs/p38 MAPK, and expression levels of heme oxygenase/NADPH quinone oxidoreductase were assessed. The nuclear factor erythroid 2‐related factor 2 nuclear translocation and the binding activity of nuclear factor erythroid 2‐related factor 2 with antioxidant response element were also evaluated. Matrine‐type alkaloids suppressed intracellular reactive oxygen species production and inhibited endothelial cell apoptosis in vivo and in vitro by recovering phosphorylation of MKK3/6 and p38 MAPK, nuclear factor erythroid 2‐related factor 2 nuclear translocation, and antioxidant response element binding activity, as well as the expression levels of heme oxygenase/NADPH quinone oxidoreductase. p38 MAPK inhibitor treatment impaired the effects of matrine‐type alkaloids in vivo and in vitro. MKK3/6 silencing impaired the effects of matrine‐type alkaloids in vitro.ConclusionsMatrine‐type alkaloids exert endothelial protective effects against advanced glycation end products induced reactive oxygen species–mediated apoptosis by targeting MKK3/6 and enhancing their phosphorylation.

Shear stress induces human aortic endothelial cell apoptosis via interleukin‑1 receptor‑associated kinase 2‑induced endoplasmic reticulum stress.

Atherosclerosis is characterized by localized lesions distributed in the arterial tree due to the shear stress produced by blood flow. Endothelial cells are directly affected by alterations in blood flow. Dysfunction and injury to endothelial cells has been hypothesized to initiate the pathological processes of atherosclerosis. The present study aimed to investigate the mechanism of shear stress-induced endothelial cellular apoptosis. Shear stress was generated using an artificial device to mimic the impact of disturbed blood flow on cultured human aortic endothelial cells (HAECs). Cellular apoptosis was assessed using a terminal deoxynucleotidyl transferase dUTP nick end labeling assay; an ELISA assay was used to detect the produced interleukin (IL)-1β; specific small interfering (si)RNA was used to knockdown the expression of interleukin-1 receptor-associated kinase 2 (IRAK2) in HAECs and the expression levels of 78 kDa glucose-regulated protein, DNA damage-inducible transcript 3 protein (CHOP), IRAK2 and IL-1β were evaluated using western blotting. The results of the present study demonstrated that artificial shear stress induced endoplasmic reticulum (ER) stress, IL-1β production and apoptosis in HAECs in a time-dependent manner. The inhibition of ER stress, and treatment with interleukin-1 receptor antagonist protein and siRNA against IRAK2 attenuated shear stress-induced CHOP signaling-mediated cellular apoptosis. Therefore, overproduction of IL-1β exacerbated shear stress-induced ER stress-mediated apoptosis via the IRAK2/CHOP signaling pathway in endothelial cells.

Sodium tanshinone IIA sulfonate improves inflammation, aortic endothelial cell apoptosis, disseminated intravascular coagulation and multiple organ damage in a rat heat stroke model.

The aim of the present study was to investigate the effects of sodium tanshinone IIA sulfonate (STS) on inflammatory responses, aortic endothelial cell apoptosis, disseminated intravascular coagulation (DIC) and multiple organ damage in an animal model of classic heat stroke (CHS). The rats in the heat stroke (HS) and STS-treated heat stroke (STS-HS) groups were placed into a pre-warmed animal temperature controller (ATC) at 35°C. The moment at which the rectal temperature reached 43.5°C was considered as the time of onset of HS. In the HS groups, the rats were removed from the ATC and allowed to recover at 26°C for 0, 2, 6 or 12 h. In the STS-HS groups, the rats received femoral vein injections of 5–40 mg/kg STS immediately following the onset of HS and were subsequently placed at a temperature of 26°C to recover for 6 h. In the present study, the serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were assessed using ELISA, and the numbers of apoptotic aortic endothelial cells were investigated using terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling combined with immunofluorescence. In the HS groups, the serum levels of TNF-α, IL-1β and IL-6, as well as the numbers of apoptotic aortic endothelial cells were increased compared with the normothermic control group. Additionally, the plasma prothrombin time, activated partial thromboplastin time and D-dimer level were significantly increased in the HS group compared with the normothermic control group following recovery for 6 h. By contrast, the platelet count was decreased in the HS group compared with the normothermic control group. The serum levels of creatinine, blood urea nitrogen, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase were increased and histopathological damage to multiple organs was observed in the HS group following recovery for 6 h. In the STS-HS groups, cytokine levels and apoptotic aortic endothelial cell numbers were reduced compared with the HS group after 6 h recovery. STS (40 mg/kg) treatment additionally improved the serum levels of organ injury indicators and plasma indicators of coagulopathy, and prevented histopathological damage to multiple organs. These findings demonstrated that STS treatment may ameliorate multiple organ damage by attenuating inflammatory responses, aortic endothelial cell apoptosis and DIC in CHS. These results suggested that STS may hold potential as an alternative therapeutic strategy for the treatment of patients with HS.

Sibutramine provokes apoptosis of aortic endothelial cells through altered production of reactive oxygen and nitrogen species

Overdose administration of sibutramine, a serotonin-noradrenalin reuptake inhibitor, is considered to elicit severe side effects including hypertension, whose pathogenic mechanism remains unclear. Here, we found that 48-h incubation with >10μM sibutramine provokes apoptosis of human aortic endothelial (HAE) cells. Treatment with the lethal concentration of sibutramine facilitated production of reactive oxygen species (ROS), altered expression of endoplasmic reticulum stress response genes (heat shock protein 70 and C/EBP homologous protein), and inactivated 26S proteasome-based proteolysis. The treatment also decreased cellular level of nitric oxide (NO) through lowering of expression and activity of endothelial NO synthase. These results suggest that ROS production and depletion of NO are crucial events in the apoptotic mechanism and may be linked to the pathogenesis of vasoconstriction elicited by the drug. Compared to sibutramine, its metabolites (N-desmethylsibutramine and N-didesmethylsibutramine) were much less cytotoxic to HAE cells, which hardly metabolized sibutramine. In contrast, both the drug and metabolites showed low cytotoxicity to hepatic HepG2 cells with high metabolic potency and expression of cytochrome P450 (CYP) 3A4. The cytotoxicity of sibutramine to HepG2 and Chang Liver cells was remarkably augmented by inhibition and knockdown of CYP3A4. This study also suggests an inverse relationship between sibutramine cytotoxicity and CYP3A4-mediated metabolism into the N-desmethyl metabolites.

Food supplementation with rice bran enzymatic extract prevents vascular apoptosis and atherogenesis in ApoE-/- mice.

Atherosclerosis is associated with reduced mononuclear cell (MNC) telomere length, and senescent cells have been detected in atherosclerotic plaques. Rice bran is a source of γ-oryzanol, phytosterols and tocols with potential lipid-lowering, antioxidant and anti-inflammatory activities. Here, we tested the hypothesis that rice bran enzymatic extract (RBEE) impacts on apoptosis, telomere length and atherogenesis in mice. Seven-week-old male ApoE-/- mice were fed high-fat diet (HFD) or isocaloric HFD supplemented with 5% (w/w) RBEE for 23weeks. Wild-type mice of the same age were kept under standard diet as controls. RBEE treatment reduced total cholesterol (19.24±1.63 vs 24.49±1.71mmol/L) and triglycerides (1.13±0.18 vs 1.75±0.22mmol/L) and augmented HDL-cholesterol (1.86±0.20 vs 1.07±0.20mmol/L). RBEE attenuated macrophage infiltration by 56.69±4.65% and plaque development (7737±836 vs 12,040±1001μm2) in the aortic sinus. In the aorta, RBEE treatment reduced expression of the apoptosis pathway components p16, p53 and bax/bcl-2 ratio. RBEE prevented apoptosis of aortic endothelial cells (2.81±0.71-1.14±0.35 apoptotic nuclei/ring for ApoE-/- HFD and ApoE-/- HFD 5% RBEE, respectively). In contrast, MNC of RBEE-fed mice exhibited enhanced apoptosis marker expression with increased p53 and bax/bcl-2 protein levels. Compared to WT, ApoE-/- mice on HFD were characterized by significant telomere shortening in aorta (11±2%) and MNC (73±7%), which was reduced by supplementation with RBEE (aorta: 40±7%; MNC: 105±10%). Expression of telomere repeat-binding factor 2 was increased in RBEE-fed mice. Long-term food supplementation with RBEE lowers cholesterol and prevents atherosclerotic plaque development in ApoE-/- mice. Differential regulation of vascular and MNC apoptosis and senescence were identified as potential mechanisms.

FOXO3A elicits vascular smooth muscle cell apoptosis through release of MMP-13 and subsequent degradation of the extracellular matrix

FOXO3A elicits vascular smooth muscle cell apoptosis through release of MMP-13 and subsequent degradation of the extracellular matrix

Enhanced matrix metalloproteinases-2 activates aortic endothelial hypermeability, apoptosis and vascular rarefaction in spontaneously hypertensive rat

Microvascular rarefaction with endothelial cells apoptosis is a common characteristic of various microvascular complications in the spontaneously hypertensive rat (SHR). Elevated levels of proteolytic (e.g. matrix metalloproteinase, MMPs) activity and apoptosis in aortic endothelial cells of SHR were found when compared to its normotensive control. However, the exact mechanisms of microvascular rarefaction and the role of MMPs in this process remain poorly understood. Besides cleavage of VEGFR2 via unbalanced MMPs, we hypothesize that selected cleavage of Beta-Catenin and VE-cadherin by MMPs could induce apoptosis of rat aortic endothelial cells (RAECs) and rarefaction. Primary RAECs were isolated, identified and used in a in-vitro model. Transwell system was used to analyze the permeability of Wistar RAECs, SHR RAECs and SHR RAECs with pretreatment by doxycycline. Qualitative and semi-quantitative analysis of major endothelial adhesion molecules were detected by immunofluorescence technique and Western blot, respectively. MMP-2 activity of SHR RAECs was increased significantly and doxycycline (50 μM) effectively reduced the level of MMP-2 and hyper-permeability in SHR RAECs. SHR RAECs showed enhanced cleavage of VEGFR2, VE-cadherin and B-catenin, which could be prevented by doxycycline (50 μM). Doxycycline (50 μM) attenuated hyper-permeability via decreased MMP-2 by protecting VEGFR2, VE-cadherin, Beta-catenin from cleavage and inhibited the reduction of mitochondrial transmembrane potential (MTP), thus prevented mitochondria-mediated apoptotic signaling and capillary rarefaction in the SHR. It might be a novel insight into the mechanisms of SHR microvascular rarefaction that is independent of pressure but relevant to MMP-2.

The effects of onion (Allium cepa) extract on doxorubicin‐induced apoptosis in aortic endothelial cells

The aim of this study was to investigate the effects of onion (Allium cepa) extracts (ACE) on doxorubicin (DOX)-induced apoptosis in aortic endothelial cells. The rats in the ACE-pretreated group were given a daily dose of 1 ml ACE for 14 days. To induce aortic endothelial cell apoptosis, DOX (30 mg kg(-1) body weight) was injected intraperitoneally by a single dose and the rats were sacrificed after 48 h. To date, no such studies have been performed on antiapoptotic potential of ACE on DOX-induced apoptosis in aortic endothelial cells. Our data indicate a significant reduction in the activity of in situ identification of apoptosis using terminal dUTP nick end-labeling in aortic endothelial cells of the DOX-treated group with ACE therapy. DOX-treated with ACE groups showed a significant decrease in malondialdehyde levels and increased levels of glutathione in comparison with the DOX-treated group. Data from our study show that prevention of endothelial cell apoptosis by ACE may contribute to the restoration of aortic endothelial dysfunction that is associated with DOX treatment.

Diazoxide inhibits aortic endothelial cell apoptosis in diabetic rats via activation of ERK

Endothelial cell (EC) survival is critical in the maintenance of endothelial function as well as in the regulation of angiogenesis and vessel integrity since endothelial dysfunction is the initial lesion of atherosclerosis. The goal of this study was to examine the effect of diazoxide, a mitochondrial ATP-sensitive K(+)(mito K(ATP)) channel opener, on aorta ECs apoptosis and its potential mechanism in Otsuka Long-Evans Tokushima Fatty (OLETF) rats at prediabetic stage. Diazoxide (25 mg kg(-1) day(-1)) was administered intraperitoneally from age 8 weeks to age 30 weeks. Thoracic aorta and cultured thoracic aortic ECs were used. The thickening of thoracic aortic wall and apoptosis of ECs were markedly increased in OLETF rats early from the age of 16 weeks, at the impaired glucose tolerance stage, compared with Long-Evans Tokushima Otsuka rats, in conjunction with intimal hyperplasia and perivascular fibrosis. In contrast, diazoxide treatment inhibited these changes. Further study strongly demonstrated that extracellular signal-regulated kinases (ERKs) are key regulatory proteins in protecting ECs from apoptosis. Diazoxide could significantly enhance phosphorylation of ERK via opening mito K(ATP) channels. This role was reversed by both 5-hydroxydecanoate, selectively closing mito K(ATP) channels, and PD-98509, MEK inhibitors. The present studies demonstrate that diazoxide prevents the onset and development of macrovascular disease in OLETF rats by inhibiting apoptosis directly via phosphorylated ERK increase in aorta ECs. Our findings establish the basis for the therapeutic potential of diazoxide in atherosclerotic disease.

Single-walled carbon nanotube induction of rat aortic endothelial cell apoptosis: Reactive oxygen species are involved in the mitochondrial pathway

The use of nano-sized materials offers exciting new options in technical and medical applications. Single-walled carbon nanotubes are emerging as technologically important in different industries. However, adverse effects on cells have been reported and this may limit their use. We previously found that 200 μg/mL of single-walled carbon nanotubes induce apoptosis in rat aorta endothelial cells. The current study aimed to determine the signaling pathway involved in this process. We found that reactive oxygen species generation was involved in activation of the mitochondria-dependent apoptotic pathway. The finding of apoptosis was supported by a number of morphological and biochemical hallmarks, including chromatin condensation, internucleosomal DNA fragmentation, and caspase-3 activation. In conclusion, our results demonstrate that single-walled carbon nanotubes induce apoptosis in rat aorta endothelial cells and that reactive oxygen species are involved in the mitochondrial pathway.

Increased Expression Ratio of Bcl‐2/Bax Is Associated with Crocin‐Mediated Apoptosis in Bovine Aortic Endothelial Cells

Crocin, extracted and purified from Gardenia jasminoids Ellis in our laboratory, has been reported to have antioxidative, hypolipidaemic and anti-atherosclerorotic effects. However, the underlying molecular mechanisms by which crocin acts as a cytoprotective agent remain to be elucidated. In the present study, we examined the mechanisms of crocin, the digentiobiosyl ester of crocetin, on bovine aortic endothelial cell apoptosis induced by hydrogen peroxide (H2O2). The cells were obtained from the thoracic aorta of newborn calves, and apoptosis was induced by 200 microM H2O2. Before addition of H2O2, the cells were pretreated with different concentrations of crocin for 6 hr. After incubation of the cells with H2O2, a comparative reverse transcriptase-polymerase chain reaction-based repeated amplification protocol assay was used to determine the ratio of bcl-2/bax mRNA expression, and cells loaded with fluo-3/AM were subjected to laser scanning confocal microscopy for detection of intracellular calcium ([Ca2+]i) levels. Treatment of the cells with H2O2 alone decreased the ratio of bcl-2/bax expression to almost twice of those of untreated cells (from 0.33+/-0.05 to 0.16+/-0.02). In the presence of 1 and 10 microM crocin, the ratios were enhanced when compared with H2O2 alone respectively (from 0.16+/-0.02 to 0.58+/-0.04, 1.18+/-0.13). The treatment of cells with crocin alone had little effect on the value of this ratio. In the presence or absence of extracellular Ca2+, H2O2 could induce intracellular calcium elevation not only in the elevation presence of extracellular Ca2+ (Hanks), but also without extracellular calcium present (D-Hanks). But the extent of [Ca2+]i under conditions lacking extracellular calcium is less. Crocin concentration dependently inhibited the [Ca2+]i elevation induced by H2O2 under these two conditions. Our data suggest that crocin may exert anti-atherosclerotic effects by increasing the expression ratio of bcl-2/bax, as a result, inhibiting the bovine aortic endothelial cell apoptosis that plays an important role in the initiation and progression of atherosclerosis.

Hyperglycemia and reactive oxygen species mediate apoptosis in aortic endothelial cells through Janus kinase 2

The generation of reactive oxygen species (ROS) has been implicated in the perturbation of endothelial function and cell death. However, the specific signaling pathways which mediate and modifying this response have not been fully elucidated. Therefore, in this study we tested the hypothesis that activation of JAK2 is involved in the aortic endothelial cell (EC) response to ROS. When ECs were exposed to HG (25 mM) for 6 h or ROS (i.e., H 2O 2 (100 μM)) for 1 h and returned to normal medium we found a decrease in cell density and morphologic signs of apoptosis. Furthermore, incubation of ECs with HG and H 2O 2 also resulted in the tyrosine phosphorylation of JAK2. In addition, pretreatment of ECs with AG-490, an inhibitor of JAK2, prevented nuclear fragmentation, whereas inhibitors of Jun kinase (SP 600125), MAP kinase (PD 98059), Src kinase (PP2) or PI-3 kinase (wortmannin) were without effect. Finally, immunoblot analysis of caspase-3 and PARP cleavage confirmed a role for activation of JAK2 in both HG- or ROS-induced apoptosis, based on inhibition by either AG-490 or adenoviral transfection with a dominant-negative JAK2 mutant. In conclusion the activation of JAK2 plays a pivotal role in oxidant stress-induced commitment of ECs to apoptosis, based on studies with HG and H 2O 2.