Insulin enhances vascular cell adhesion molecule-1 expression in human cultured endothelial cells through a pro-atherogenic pathway mediated by p38 mitogen-activated protein-kinase

Aims/hypothesis Although hyperinsulinaemia in Type 2 diabetes in states of insulin resistance is a risk factor for atherosclerotic vascular disease, underlying mechanisms are poorly understood. We tested the hypothesis that insulin increases monocyte-endothelial interactions, which are implicated in atherosclerosis.Methods We treated human umbilical vein endothelial cells with insulin (10^–10 to 10^–7 mol/l) for 0 to 24 h. To dissect potentially implicated signal transduction pathways, we treated endothelial cells with known pharmacological inhibitors of two distinct insulin signalling pathways: the phosphatidylinositol-3-kinase (PI3-kinase) inhibitor wortmannin (3×10^–8 to 10^–6 mol/l), involved in insulin-induced endothelial nitric oxide synthase stimulation, and the p38 mitogen-activated protein (p38MAP) kinase inhibitor SB-203580 (10^–7 to 2×10^–6 mol/l). We measured adhesion molecule expression by cell surface enzyme immunoassays and U937 monocytoid cell adhesion in rotational adhesion assays.Results At pathophysiological concentrations (10^–9 to 10^–7 mol/l), insulin concentration-dependently induced vascular cell adhesion molecule (VCAM)-1 (average increase: 1.8-fold) peaking at 16 h. By contrast, the expression of intercellular adhesion molecule-1 and E-selectin were unchanged. The effect on VCAM-1 was paralleled by increased U937 cell adhesion. In the absence of cytotoxicity, wortmannin significantly potentiated the effect of insulin alone on VCAM-1 surface expression and monocytoid cell adhesion, whereas SB-203580 (10^–6 mol/l) completely abolished such effects.Conclusions/interpretation These observations indicate that insulin promotes VCAM-1 expression in endothelial cells through a p38MAP-kinase pathway, amplified by the PI3-kinase blockage. This could contribute to explaining the increased atherosclerosis occurring in subjects with hyperinsulinaemia, or in states of insulin resistance, which feature a defective PI3-kinase pathway.Abbreviations VCAM-1 vascular cell adhesion molecule-1 - ICAM-1 intercellular adhesion molecule-1 - PI3-kinase phosphatidylinositol 3-kinase - MAP mitogen-activated protein - NO nitric oxide - EIA enzyme immunoassays     

霉酚酸酯抑制内皮细胞表面粘附分子的表达

目的 :观察霉酚酸酯 (MMF)对炎症因子刺激下内皮细胞表面粘附分子ICAM 1表达的影响。　 方法 :以TNFα(2 0 μg/L)刺激内皮细胞 ,细胞表面的ICAM 1蛋白表达以流式细胞术检测 ,内皮细胞ICAM 1mRNA表达采用逆转录 半定量PCR法进行测定。　 结果 :TNFα(2 0 μg/L)刺激内皮细胞 2 4h ,内皮细胞表面的粘附分子ICAM 1的蛋白和mRNA表达明显上升。MMF可以抑制内皮细胞的ICAM 1蛋白和mRNA的表达 ,这一抑制作用随着MMF剂量的增加而增强。　 结论 :MMF可以抑制内皮细胞粘附分子ICAM 1的表达     

Effect of an aldose reductase inhibitor on type IV collagen production by human endothelial cells cultured in high glucose

Summary Diabetic microangiopathy is characterized by a thickening of capillary basement membranes associated with type IV collagen accumulation. An increase in type IV collagen content of the aortic wall is also observed in macroangiopathy. In order to analyse the importance of the polyol pathway in the development of the collagen metabolism alterations seen in diabetic angiopathy and their prevention by aldose reductase inhibitors, we have studied the effects of sorbinil on the high glucose-induced stimulation of type IV collagen biosynthesis in human umbilical vein endothelial cells. Primary cultures were exposed to high glucose (16.7 mmol/l), with and without 0.11 mmol/l sorbinil, for 3 or 6 days after beginning of confluence. We measured the soluble type IV collagen secreted into the culture medium and the insoluble type IV collagen accumulated in the extracellular matrix and cells, by ELISA. We also studied [¹⁴C]proline incorporation into the newly synthesized collagenous and total proteins in the culture supernatant and in the extracellular matrix and cell fraction. High glucose decreased the number of cells and increased the amount of type IV collagen in the culture supernatant and in the extracellular matrix and cell fraction. It also increased proline incorporation into the newly synthesized collagenous and total proteins in the culture supernatant and in the extracellular matrix and cell fraction. Sorbinil corrected all these high glucose-induced alterations. The corrective effects of sorbinil on the proliferation and on type IV collagen metabolism of endothelial cells cultured in high glucose may be attributed to prevention of polyol pathway dysregulation.Abbreviations AGE Advanced glycation end product - AR aldose reductase - ARI aldose reductase inhibitor - BM basement membrane - EC endothelial cells - GGHG glucosyl-galactosyl-hydroxylysyl-collagen glucohydrolase - HUVEC human umbilical vein EC - HS human serum - PBS phosphate-buffered saline - PKC protein kinase C     

Influence of glucose,insulin and sera from diabetic patients on the prostacyclin synthesis in vitro in cultured human endothelial cells

Summary The effects of glucose, insulin and sera from Type 1 (insulin-dependent) diabetic patients on the synthesis of prostacyclin in vitro were studied in confluent primary cultures of human endothelial cells. The stable metabolite, 6-keto-prostaglandin F₁, was measured in growth medium after 24 h of incubation with endothelial cells in a buffer incubated with the cells for 10 min on a rocker platform, and in a buffer solution of ruptured cells. Glucose (11, 15, 20 or 25 mmol/l) and glucose (11 mmol/l) plus insulin (10³, 10⁴ or 10⁶ mU/l) in growth medium did not have any effects on the prostacyclin synthesis. The prostacyclin synthesis was significantly reduced in cell cultures incubated with medium supplemented with 10% serum from patients with Type 1 diabetes (p<0.01) compared with cultures incubated with pooled serum from healthy blood donors. These data suggest that diabetic sera inhibit the prostacyclin synthesis in cultured endothelial cells unrelated to the glucose and insulin levels.     

The polyol pathway and glucose 6-phosphate in human endothelial cells cultured in high glucose concentrations

Summary In an attempt to identify the mechanisms underlying the ill effects of high glucose previously described in cultured human endothelial cells, we have investigated in these cells the activity of the polyol pathway and accumulation of glucose 6-phosphate, a powerful agent of non-enzymatic glycosylation. Sorbitol accumulation varied among different batches of cells (primary cultures). In presence of 5 mmol/l glucose the cellular sorbitol content ranged from 0.04 to 0.12 nmol/10⁶ cells. When cells were exposed to 20 mmol/l glucose the sorbitol content increased by 2- to 3-fold to concentrations of 0.08–0.38 nmol/10⁶ cells (p<0.01). Addition to the culture medium of 100 mol/l Sorbinil, an inhibitor of aldose reductase, resulted in a substantial inhibition of sorbitol accumulation throughout the 14 days in culture, but the degree of inhibition varied inversely with the duration of cell exposure to high glucose (70% inhibition in cells exposed to high glucose and Sorbinil for 1–3 days versus 14% inhibition in cells exposed for 14 days, p<0.01). Sorbinil treatment failed to improve even slightly the abnormalities in cellular replication induced by high glucose. The cellular content of glucose 6-phosphate was augmented 3-fold by exposure to 20 mmol/l glucose (p<0.001). In conjunction with other studies these results indicate that in this model the polyol pathway is not an osmotically or metabolically important mechanism of glucotoxicity, and that the inhibitory activity of Sorbinil on the polyol pathway of human tissues may be a function of their length of exposure to hyperglycaemia. The consequences of intracellular accumulation of glucose 6-phosphate await investigation.     

小干扰RNA对大鼠血管内皮细胞ICAM-1表达的抑制作用

目的:探讨小干扰RNA对大鼠血管内皮细胞细胞间黏附分子-1(ICAM-1)表达的抑制作用.方法:使用 ICAM-1siRNA及错配siRNA转染肿瘤坏死因子-α刺激过的大鼠血管内皮细胞,聚合酶链反应和蛋白印迹检测转染后48 h ICAM-1 mRNA和蛋白表达水平.结果:与空白对照组比较,大鼠血管内皮细胞在转染48 h后ICAM-1 mRNA表达减少90.0％,蛋白表达减少83.0％.结论:使用小干扰RNA能有效抑制大鼠血管内皮细胞ICAM-1表达.     

红芪多糖对高糖条件下人脐静脉内皮细胞功能的影响

目的研究红芪多糖（HPS）对高糖条件下人脐静脉内皮细胞（HUVEC）合成和释放一氧化氮（NO）和内皮素-1（ET-1）的影响及作用机制。方法从新鲜脐带中分离HUVEC进行鉴定、培养,细胞分为正常对照组、高糖组（30mmol／L葡萄糖）和HPS干预组。MTT比色法分析HPS对高糖诱导HUVEC增殖率的影响,流式细胞术Annexin—V／PI双染法检测细胞凋亡,硝酸盐还原酶法检测上清液中NO的水平,分光光度法检测细胞内一氧化氮合酶（NOS）、诱导型一氧化氮合酶（iNOS）的浓度,酶联免疫吸附（ELISA）法检测上清液中ET-1的含量,实时荧光定量聚合酶链反应（RT—PCR）检测细胞内皮型一氧化氮合酶（eNOS）、ET-1和c-Jun氨基末端激酶l（JNKl）mRNA的表达水平。组间差异显著性检验使用单因素方差分析,组间两两比较使用LSD法。结果高糖组在6h[（82．4±3．5）％]、24h[（68．2±1．4）％]、48h[（63．0±2．9）％]的细胞增殖率显著低于对照组（100％,P〈0．05）;HPS干预组细胞增殖率随浓度变化呈现先上升后下降的趋势,其中50mg／L[（85．34-4．6）％]、100mg／L[（89．6±1．1）％]、200mg／L[（88．8±3．6）％]HPS干预组较高糖组增加,差异具有统计学意义（均P〈0．05）;高糖组NO[（24．84±1．34）μmol／L]、NOS[（0．54±0．06）U／m1]含量较正常对照组呈现下降的趋势,iNOS[（0．133±0．015）U／m1]和ET_l[1（0．740±0．070）ng／m1]含量则在各时间点均高于对照组,HPS干预组升高不同时间点HUVEC内NO[（23．20±0．55）p．mol／L]、NOS[（0．46±0．10）U／m1]、以及降低iNOS[（0．08±0．020）U／m1]和ET-1[（0．710±0．030）μg/L]的变化,P〈0．05,使其趋向正常水平;HPS可提高高糖所致内皮细胞eNOSmRNA的水平[（0．33±0．02）比（0．23±0．04）],降低ET-1mRNA的水平（2．28±0．31比2．79±0．29）;高糖组细胞内JNK1mRNA水平表达（2．95±0．05）较正常对照组（1．00±0．00）显著增加（P〈0．05）,而HPS干预组（1．45±0．05）则较高糖组（2．95±0．05）明显减少（P〈0．05）。结论HPS对体外高糖诱导HUVEC损伤具有保护作用,这一作用可能与抑制JNK信号通路有关。     

青藤碱对肿瘤坏死因子-α诱导人脐静脉内皮细胞VCAM-1表达影响初步研究

目的 进一步研究青藤碱(SIN)对肿瘤坏死因子(TNF)-α诱导脐静脉内皮细胞(HUVECs)血管细胞黏附分子(VCAM)-1表达的影响.方法 从新鲜脐带中分离培养HUVECs.用TNF-α诱导HUVECs表达VCAM-1,实验组加入不同浓度的SIN(0.25、0.0和1.0 mol/L)或地塞米松(1.0×106mol/L)分别进行或联合进行干预,用流式细胞仪检测细胞表面VCAM-1表达.结果 与TNF-α刺激组相比,SIN干预组细胞表面VCAM-1表达下降,抑制作用以1.0 mol/L最为显著.联合地塞米松(1.0x106 mol/L)进行干预,可加强SIN对TNF-α诱导的VCAM-1表达的抑制作用.结论 SIN可抑制TNF-α诱导的脐静脉内皮细胞VCAM-1的表达.青藤碱与地塞米松对TNF-α诱导的VCAM-1表达的抑制有协同作用.     

艾塞那肽抑制高糖诱导内皮细胞凋亡的作用机制

在正常糖浓度(5.5 mmol/L)和高糖(33 mmol/L)培养的人脐静脉内皮细胞(HUVECs)分别加入不同浓度的艾塞那肽并干预不同时间后,噻唑蓝(MTF)法检测细胞活力,应用流式细胞仪检测细胞早期凋亡率,Western印迹法检测蛋白激酶B(Akt)磷酸化、Bcl-2和Bax蛋白表达水平.结果显示,HUVECs经高糖培养48和72 h后,细胞活力明显下降(P＜0.01).经1、10和100 nmol/L艾塞那肽干预48 h后,细胞活力明显增加,并呈浓度依赖性(P＜0.01).与正常糖浓度组比较,高糖组细胞凋亡率升高,Akt磷酸化和Bcl-2蛋白表达水平下降,Bax蛋白表达增加,Bcl-2/Bax比值降低(P＜0.01).艾塞那肽干预后,细胞凋亡率下降,Akt磷酸化和Bcl-2蛋白表达增加,Bax蛋白表达下降,Bcl-2/Bax比值升高(P＜0.01),而艾塞那肽的作用可被磷酸肌醇3激酶(PI3K)抑制剂LY294002所对抗(P＜0.01).提示艾塞那肽可通过PI3 k/Akt信号通路调节Bcl-2/Bax蛋白表达来抑制高糖诱导的内皮细胞凋亡,起到保护内皮细胞的作用.     

Glucose modulation of aldose reductase mRNA expression and its activity in cultured calf pulmonary artery endothelial cells

Summary We examined the effect of glucose on aldose reductase mRNA expression and its activity in calf pulmonary artery endothelial cells. After the cells were exposed to 18 mmol/l glucose, aldose reductase mRNA expression began to increase at 6 h, reached a maximum (about 2.4-fold increase) at 12 h, and thereafter gradually decreased. Aldose reductase activity was found to strongly correlate with aldose reductase mRNA expression after cells were exposed to 18 mmol/l glucose. In contrast, aldose reductase mRNA expression was significantly decreased following exposure to 55 mmol/l glucose. Aldose reductase activity was also decreased at 24 h after 55 mmol/l glucose. The increase in aldose reductase mRNA level caused by glucose was inhibited by 1 g/ml of actinomycin D. These phenomena appear to be glucose-specific since neither 3-O-methylglucose nor fructose affected the levels of aldose reductase mRNA. We clearly demonstrate that aldose reductase mRNA level and its activity are modulated by glucose in calf pulmonary artery endothelial cells. Our data suggest that activation of aldose reductase in endothelial cells may contribute to the development of diabetic macroangiopathy.     

表没食子儿茶素没食子酸酯对高糖环境下内皮细胞氧化应激的影响

目的研究不同剂型表没食子儿茶素没食子酸酯（EGCG）对高糖诱导人脐静脉内皮细胞（HUVEC）氧化应激损伤所引起凋亡的抑制作用及人核因子-κB P65（NF-κB P65）表达的影响。方法从新鲜脐带中分离培养HUVEC。用高糖诱导HUVEC表达NF-κB P65,实验组加入不同浓度的EGCG（12．5、25、50、100、200μmol／L）进行干预,PCR检测NF-κB P65mRNA的表达,AV-PI法检测凋亡细胞。结果高糖可诱导HUVEC凋亡,NF-κB P65表达增高;EGCG可抑制NF-κB P65的表达,降低凋亡指数,具有一定的时效关系、剂量关系。结论EGCG可在一定程度上抑制高糖诱导的氧化应激损伤所致的细胞凋亡。EGCG可能是通过抑制高糖所致的NF-κB增高,从而调控HUVEC细胞凋亡过程,发挥对HUVEC的保护作用。     

Glucose inhibits replication of cultured human endothelial cells

Summary Diabetes is an important risk factor for atherosclerosis but the mechanism of the risk is unknown. As endothelial injury is considered to be an early event in the development of atherosclerosis, the effect of glucose on endothelial cell replication was studied. Concentrations of glucose of 11.2, 16.8 and 22.4 mmol/l inhibited DNA synthesis in cultured human umbilical venous endothelial cells by 8.1±10.8, 24.3±8.8 and 30.9±7.4%, respectively. Glucose also inhibited the proliferative response of endothelial cells to experimental wounds in the cell layer. Sorbitol (22.4 mmol/l) inhibited endothelial cell DNA synthesis by 50±13.6%, but mannitol (22.4 mmol/l) inhibited DNA synthesis by only 3±24.3%. It is suggested that in diabetic subjects, high blood glucose levels may cause endothelial injury, or inhibit its repair, and hence allow the exposure of the arterial media to plasma and its constituents.     

Differential modulation of adhesion molecule expression by hydroxycarbamide in human endothelial cells from the micro- and macrocirculation: potential implications in sickle cell disease vasoocclusive events

Background

All the cellular partners of the vascular system and especially endothelial cells are involved in the pathophysiology of the vasoocclusive crises associated with sickle cell disease. In sickle cell disease, circulating cells adhere abnormally to endothelial cells in a chronic pro-inflammatory context. Hydroxycarbamide is the only drug with demonstrated efficacy to reduce the frequency of vasoocclusive crises. Here, we investigated the effects of hydroxycarbamide and/or cytokines on the expression of genes related to adhesion events in endothelial cells from three different vascular sites.

Design and Methods

Endothelial cells representative of the macro- (HUVEC) or microcirculation (TrHBMEC and HPMEC) were grown in the presence or absence of hydroxycarbamide and/or cytokines (TNFα and IFNγ). Expression of genes encoding adhesion proteins was analyzed by RQ-PCR, ELISA, flow cytometry, in situ ELISA for extracellular matrix proteins, and Western blot.

Results

In cells from the microcirculation, expression of TSP-1, vWF, and PECAM-1 genes was decreased by hydroxycarbamide and/or cytokine treatment at the mRNA level. In the macro-circulation their expression was unaffected or increased. Hydroxycarbamide significantly decreased vWF incorporated in the TrHBMEC extracellular matrix. CD36 mRNA was strongly down-regulated by cytokines in HPMEC, the only cell type in which it is expressed. Hydroxycarbamide decreased soluble PECAM-1 in HUVEC supernatants.

Conclusions

Our results highlight the heterogeneity of vascular endothelial cell responses to hydroxycarbamide and/or cytokines depending upon their origin. They also suggest that hydroxycarbamide has an anti-adhesogenic effect on endothelial cells, but by mechanisms which could vary according to their macro- or microcirculation and organ origin.     

蛋白激酶C活性变化影响内皮-单核细胞黏附

目的探讨蛋白激酶C(PKC)激动剂佛波酯(PMA)和抑制剂钙磷酸结合蛋白(Calphostin C)对荷脂ECV304内皮细胞黏附能力影响的机制。方法采用体外培养和直接计数法观察内皮细胞黏附能力变化;PepTag Non-Radioactive Assay法定性定量细胞膜上PKC活性状态;RT-PCR和Western blot检测黏附相关指标细胞间黏附分子-1(ICAM-1)、I-κBα和ezrin表达的变化。结果100nmol/L PMA在激活细胞膜PKC活性的同时,可以与氧化型低密度脂蛋白(ox-LDL)协同增强ICAM-1和ezrin表达,但下调I-κBα的表达,并使内皮-单核细胞的黏附能力增强;300nmol/L Calphostin C基本上可以逆转50μg/ml ox-LDL诱导的酶活化和对ICAM-1、I-κBα和ezrin表达的调节,即PKC活性减弱,ICAM-1和ezrin表达下调,I-κBα表达上调,内皮细胞黏附能力明显降低。结论PMA、Calphostin C→PKC→NF-κB/I-κB→ICAM-1→Adhesion可能是黏附信息传递整合的一条重要途径,而黏附分子→ezrin→细胞骨架途径则可能起到加强内皮-单核细胞间黏附能力的作用。     

高浓度葡萄糖对人脐静脉内皮细胞内皮型一氧化氮合酶活性及其蛋白表达的影响

不同浓度葡萄糖及高浓度葡萄糖（高糖）加胰岛素孵育人脐静脉内皮细胞（HUVECs）不同时间后，高浓度葡萄糖呈浓度和时间依赖性明显抑制内皮型一氧化氮合酶（eNOS）活性，生理浓度的胰岛素可部分地逆转高糖对eNOS活性及其表达的抑制作用。     

同型半胱氨酸对血管内皮细胞E-选择素、IL-6分泌的影响

目的探讨同型半胱氨酸（homocysteine,Hcy）对人脐静脉内皮细胞E-选择素、白细胞介素6（IL6）分泌的影响。方法在人脐静脉内皮细胞ECV304培养基中加入不同浓度Hcy,孵育不同时间,用ELISA法分别测定培养上清液中E-选择素及IL6的含量。结果终浓度为250μmol/L的Hcy孵育内皮细胞,E选择素的分泌在4h显著上调,6h达峰值;IL6的分泌在6h开始升高,24h达峰值,之后随着时间的延长逐渐下降。Hcy呈浓度依赖性（50μmol/L～500μmol/L）促进内皮细胞E选择素及IL6的分泌。结论Hcy能刺激血管内皮细胞分泌E选择素及IL6。     

Expression of adhesion molecules in endothelial cells during allogeneic bone marrow transplantation

Abstract: Endothelial cell activation during allogeneic bone marrow transplantation, mainly in acute graft-versus-host disease (aGvHD) was studied in 23 recipients and 5 controls using anti-von Willebrand factor (vWF) antibody, antibodies to endothelial leukocyte adhesion molecule-1 (ELAM-1), vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1), and anti-HLA-DQ antibody, by immunohistological staining of skin. vWF extravasation, ELAM-1 and VCAM-1 expression were present in most recipients with a cutaneous rash which was confirmed as an aGvHD by histological examination (documented aGvHD) (p = 0.005 for vWF extravasation and ELAM-1 expression and p = 0.03 for VCAM-1 expression in comparison with the controls). In recipients with a rash, the cases displaying vWF extravasation and ELAM-1 expression were significantly more numerous in those with a documented aGvHD than in those without histological features of aGvHD (p = 0.01). vWF extravasation and ELAM-1 occurred concomitantly (p<0.01). This study demonstrates that, during the course of skin aGvHD following bone marrow transplantation, there is transient expression of ELAM-1 and VCAM-1 by endothelial cells and simultaneous vWF extravasation, indicating an intense inflammation with endothelial cell participation.