Endothelium : journal of endothelial cell research最新文献

Oxidative damage of endothelial tight junction permeability is involved in the pathophysiology of a variety of vascular diseases. The authors studied the role of the antioxidant enzyme, human glutathione-S-transferase A4-4 (hGSTA4-4), in regulating expression of major molecules of tight junction in vascular endothelial cells under oxidative stress induced by H(2)O(2). A vascular endothelial cell line, mouse pancreatic endothelial cells (MS1), was transduced with recombinant adenoviral vector containing hGSTA4-4 gene. hGSTA4-4 induced expression of tight junction proteins occludin and zonula occludens (ZO)-1 under oxidative stress. Increased hGSTA4-4 expression correlated with increased transepithelial electrical resistance and decreased tyrosine phosphorylation of occludin and ZO-1 following exposure to H(2)O(2). In addition, morphologic dissociation of occludin, ZO-1, and F-actin during oxidative stress was reduced in hGSTA4-4-expressing cells. To explore a genetic approach for vascular diseases associated with disruption of tight junction proteins, we introduced the same viral vector to blood vessels of mice, rats, and rabbits ex vivo and found strong expression of hGSTA4-4 in endothelial cells. These results demonstrate that oxidative stress mediated disruption of tight junctions in endothelial cells may be attenuated by hGSTA4-4 expression.

Both senescence and apoptosis of vascular endothelial cells (VECs) are involved in the development of cardiovascular diseases, including atherosclerosis. To understand the association between senescence and apoptosis in vascular endothelial cells, the authors first explored whether senescence and apoptosis took place at the same time in human umbilical vein endothelial cells (HUVECs) deprived of the growth factors. Integrin beta4 is a key factor in HUVEC apoptosis, to know whether this integrin is implicated in VEC senescence, the authors checked the changes of integrin beta4 level during HUVEC aging. Then the authors investigated the effects of 3BDO (3-benzyl-5-((2-nitrophenoxy)methyl)-dihydrofuran-2(3H)-one) on the senescence induced by deprivation of serum and fibroblast growth factor (FGF)-2. The results showed that deprivation of growth factors not only induced apoptosis, but also triggered senescence in HUVECs. The authors found that the level of integrin beta 4 was increased markedly during HUVEC senescence. 3BDO (20 to 60 microg/mL) could inhibit both senescence and apoptosis and depress integrin beta 4 level. The data suggested that integrin beta4 might be a pivotal factor in the relationship between senescence and apoptosis.

Ligand-specific integrins are thought to play a critical role in regulating multiple biological processes. However, the mechanisms by which ligand-specific integrins mediate external stimuli and activate intracellular signaling pathways remain to be elucidated. The aim of this study was to clarify the role of ligand-specific integrins in the morphological changes induced by cyclic strain (CS) via the p38 mitogen-activated protein kinase (p38 MAPK) pathway. Endothelial cells (ECs) were cultured on collagen (a ligand for integrin alpha 2 beta1, but not for alpha 5 and beta 4)-coated flexible plates and incubated for 24 h with or without anti-alpha2 integrin antibody (anti-alpha2), anti-alpha5, anti-beta1, or anti-beta4. ECs were then subjected to 15.6% average CS at 60 cycles/min up to 24 h. After exposure to CS, the cell shape index (defined as (4pi x cell area)/(cell perimeter)(2)), the cell orientation angle, and activation of p38 MAPK were assessed. ECs in the absence of integrin-blocking antibodies were elongated and aligned in response to CS. Anti-alpha 2 and anti-beta1 abolished both morphological changes of ECs as well as the activation of p38 MAPK. In contrast, anti-alpha 5 and anti-beta 4 inhibited neither morphological changes of ECs nor the activation of p38 MAPK. Our results indicate that ligand-specific integrins play a crucial role in the morphological changes of ECs induced by CS via the p38 MAPK pathway.

Recent evidences suggest that modulation of vascular structure by matrix metalloproteinases (MMPs) could be a main determinant of acute cardiovascular events in high-risk subjects. The authors consecutively selected 46 subjects affected by familial combined hyperlipidemia (FCH), 44 by metabolic syndrome (MS), 44 by FCH and MS, and 40 healthy subjects. All these subjects were firstly diagnosed and not treated with lipid-lowering, antihypertensive, or antidiabetic drugs. A 12-h fasting blood sample was obtained from each patient, and plasma levels of MMP-2 and MMP-9 were measured together with their tissue inhibitors and a full set of laboratory cardiovascular disease markers. MMP-2 plasma levels were not significantly different among the considered groups. MMP-9, tissue inhibitor of MMP (TIMP)-1, and TIMP-2 are significantly higher in FCH (p < .001) and MS (p < .001) patients than in healthy controls, and they are also higher in MS patients than in FCH ones (p < .001). TIMP-1 (p < .001) and TIMP-2 (p < .001), but not MMP-9, are also significantly higher in subjects with MS associated to FCH than in patients with MS alone. No specific correlation among MMPs, TIMPs, and the other studied parameters has been observed in the whole sample and in the four above-defined subgroups. MMP-9, TIMP-1, and TIMP-2 plasma levels could be significant determinant and/or diagnostic markers of MS but not of FCH. However, the superposition of MS on FCH further increases the plasma level of these parameters. The prognostic value of this observation has to be evaluated.

It has not been established yet whether patients who suffer myocardial infaction (MI) in the absence of classic risk factors also have endothelial dysfunction (ED), as has been shown for patients with risk factors, and if so, to what extent it is manifested. Young male patients in the stable phase after MI were included in the study. At the time of MI, 20 patients had high and 21 patients low expression of risk factors. The control group consisted of 35 healthy age-matched males. ED was estimated by ultrasound measurement of the endothelium-dependent dilation of the brachial artery, induced by the reactive hyperemia test. Compared to the control group, the level of endothelium-dependent vasodilation was significantly reduced in both groups of patients (controls: 9.1% +/- 5.6%; patients with high risk: 5.5% +/- 5.1%; patients with low risk: 5.6 +/- 3.5 %; ANOVA, p<.01). There was no difference between both groups of patients. These results showed that ED is not associated or due only to classic risk factors. It appears that ED may occur and precede development of atherosclerosis in the absence of classic risk factors. These novel findings can have important clinical implications.

Microvascular endothelial activity (EA) after stimulation with iontophoretically administered acetylcholine was evaluated using laser Doppler fluxmetery (LDF) and calibrated photoplethysmography (c-PPG) in normal patients and patients with peripheral artery disease (PAD). The patients included 79 non-PAD subjects and 51 patients with PAD. Upper and lower extremity EA was examined using LDF and c-PPG after acetylcholine iontophoresis for 10 min. Sensitivity and specificity were assessed using integrated area under response curve. In non-PAD patients, the EA by LDF in the upper extremity was significantly lower in the older patients compared to the younger patients. Conversely, EA by LDF detected no significant difference between these groups in the lower extremity.With c-PPG, the EA was slightly reduced in the upper but not in the lower extremity in older patients. Comparing PAD patients to the older patients, there was a significantly lower EA response in the upper and lower extremities by LDF. Likewise, c-PPG detected a highly significantly reduced EA in the upper and lower extremities for PAD patients. These results indicated that using a noninvasive technique to determine EA, there were significant differences in the EA response to acetylcholine between those with PAD and normal patients over the age of 50. Importantly, the EA response was reduced in the upper and lower extremities, indicating systemic disease of the endothelium in PAD patients.

EP2306 and EP2302 are two novel squalene synthase inhibitors with hypolipidemic, antiatherosclerotic, and antioxidant properties. In the present study, the authors investigated their effect on the expression and activity of endothelial nitric oxide synthase (eNOS) in cultured bovine aortic endothelial (BAE) cells and calf pulmonary artery endothelial (CPAE) cells. eNOS concentration was determined by immunoassay and eNOS activity by measuring the conversion of [(3)H]arginine to [(3)H]citrulline. Basal levels of eNOS in untreated BAE cells were 13.3 +/-1.6 ng/mg protein. Stimulation for 4 h with 30 microM of EP2306 or EP2302 resulted in increased eNOS protein level to 40% +/- 10% (p<.05) or 165% +/- 15% (p < .05) of unstimulated levels, respectively. Basal levels of eNOS in untreated CPAE cells were 3.4 +/- 0.4 ng/mg protein. Stimulation of CPAE cells for 4 h with 30 microM of EP2306 or EP2302 resulted in increased eNOS protein level to 195% +/- 24% (p < .05) and 152% +/- 19% (p < .05) of unstimulated levels, respectively. Despite their stimulatory action on eNOS expression, EP2300 compounds failed to induce any significant changes on eNOS enzymatic activity in BAE and CPAE cells. The finding that EP2300 compounds significantly increase the accumulation of eNOS in cultured endothelial cells sheds some light into their mechanism of action and supports a possible protective role of these compounds in atherosclerosis-related diseases.

Resistin, a novel adipokine, was recently suggested to be involved in the development of endothelial dysfunction. However, the mechanisms of how resistin works are still unknown. This study was performed to investigate the relationship between resistin and phosphatidylinositol 3-kinase (PI3K), with the aim of gaining insight to the mechanisms by which resistin induces changes of secretion function of vascular endothelium. This study was conducted on 60 male 4-week-old Sprague-Dawley rats, which were randomly divided into four groups: resistin group (RS; n = 8), normal saline group (NS; n = 8), high-fat diet group (HF; n = 36), and control group (CO; n = 8). The resistin group was administered two injections of rat recombinant resistin. The diet-induced hyperresistinemia rats were selected from the HF group after the HF group was administered a high-fat diet for 8 weeks. The diet-induced hyperresistinemia rats were randomized into the antibody group (AB; n = 8) and hyperresistinemia group (HR; n = 8). The antibody group was given injections of resistin antibody twice per day and for 3 days. Immunohistochemistry was employed to examine the expression of PI3K p85alpha subunit and endothelial nitric oxide synthase (eNOS) in thoracic artery endothelium. In the resistin group, the levels of endothelin (ET), plasminogen activator inhibitor (PAI), and von Willebrand factor (vWF) were higher and NO was lower than those in the normal saline group. The NO level increased and ET, PAI, and vWF levels decreased in the antibody group when compared with the hyperresistinemia group. After administration of resistin antibody, the expression of PI3Kp85alpha and eNOS proteins in the antibody group was significantly increased but still differed significantly from those in the control group. PI3K grey value was correlated with resistin, PAI-1, vWF, NO, and the expression of eNOS (p < .05), after controlling for the effect of insulin. Resistin can affect the protein expression of PI3Kp85alpha, stimulate release of PAI-1, vWF, and ET, and down-regulate eNOS. The effect of resistin on PI3K signaling pathway might contribute to the development of endothelial secretion dysfunction in young rats.

Endothelial nitric oxide synthase (eNOS) is regulated by phosphorylation of Ser(1177) and Thr(495), which affects NO bioavailability. Cigarette smoke disturbs the eNOS-cGMP-NO pathway and causes decreased NO production. Here the authors investigated the acute effects of cigarette smoke on eNOS phosphorylation, focusing on protein kinases (PKs). Endothelial cell culture was concentration- and time-dependently treated first with cigarette smoke buffer (CSB), then with reduced glutathione (GSH) or various PK inhibitors (H-89, LY-294002, Ro-318425, and ruboxistaurin). eNOS, phospho-Ser(1177)-eNOS, phospho-Thr(495)-eNOS, Akt(PKB), and phospho-Akt protein levels were determined by Western blot. CSB increased the phosphorylation of eNOS at Ser(1177) and more at Thr(495) in a concentration- and time-dependent manner (p < .01, p < .05 versus control, respectively) and resulted in the dissociation of the active dimeric form of eNOS (p < .05). GSH decreased the phosphorylation of eNOS at both sites (p < .05 versus CSB without GSH) and prevented the decrease of dimer eNOS level. CSB treatment also decreased the level of phospho-Ser(473)-Akt (p < .05 versus control). Inhibition of PKA by H-89 did not affect CSB-induced phosphorylation, whereas the PKB inhibitor LY-294002 enhanced it at Ser(1117). The PKC blockers Ro-318425 and ruboxistaurin augmented the CSB-induced phosphorylation at Ser(1177) but decreased phosphorylation at Thr(495) (p < .05 versus CSB). Cigarette smoke causes a disruption of the enzymatically active eNOS dimers and shifts the eNOS phosphorylation to an inhibitory state. Both effects might lead to reduced NO bioavailability. The shift of the eNOS phosphorylation pattern to an inhibitory state seems to be independent of the PKA and phosphoinositol 3-kinase (PI3-K)/Akt pathways, whereas PKC appears to play a key role.

Hypoxia is related to the etiology of numerous pathological disease states, such as the formation of tumors or diverse retinopathies. Epigallocatechin-3-gallate (EGCG), a potent polyphenolic antioxidant and antiangiogenic compound found in green tea, has been shown to suppress the growth of blood vessels necessary for the growth of tumors and the induction of retinopathies. However, only a few studies have been carried focusing on the protective effects of EGCG on hypoxia-induced injury of cultured endothelial cells. The present study investigated the effects of EGCG on Na(2)S(2)O(4)-induced hypoxic injury in three types of cultured endothelial cells, primary isolates of normal human umbilical vein endothelial cells (HUVECs), and two transformed endothelial cells lines, RF/6A and ECV304. Our results indicated that Na(2)S(2)O(4) inhibited the growth of HUVE, RF/6A, and ECV304 cells in a dose-dependent manner; EGCG also exerted inhibitory effects on the growth of the three cell types, but the toxicity of EGCG to HUVECs was less than to RF/6A and ECV304 cells. The viability of HUVE, RF/6A, and ECV304 cells treated with EGGC were the lowest at 24, 24, and 36 h, respectively, and the IC(50) of EGCG were 420 +/- 8.0, 125 +/- 7.1, and 75 +/- 5.1 microM, respectively. Furthermore, EGCG, an efficient nontoxic agent, protected all three cell types from Na(2)S(2)O(4)-induced hypoxia injury, providing partial protection from hypoxia-induced injury in normal endothelial cells at 100, 30, and 10 microM for HUVE, RF/6A, and ECV304 cells, respectively.