Purification and characterisation of recombinant rabbit plasminogen activator inhibitor-1 expressed in Saccharomyces cerevisiae

The rabbit plasminogen activator inhibitor-1 (PAI-1) cDNA has been isolated from a rabbit corneal cell cDNA library. The cDNA encodes a 402-amino acid (AA) protein that shares an overall 66% AA sequence identity with the rat, mouse, bovine and human forms of PAI-1 and exhibits the greatest AA sequence identity (85%) with human PAI-1. Three potential N-linked glycosylation sites and the P1, P1′ reactive centre of PAI-1 are conserved among all five species of animals. The cDNA encoding the proposed mature form of rabbit PAI-I was expressed in Saccharomyces cerevisiae as an intracellular, non-glycosylated protein. The purified, recombinant rabbit PAI-1 (R-rPAI-1) has an apparent M_r of 39 100 and exists primarily in a latent form which can be activated by guanidine HCI treatment. Activated R-rPAI-1 exhibits in vitro functional properties which are virtually indistinguishable from a recombinant, non-glycosylated form of human PAI-I and from fully glycosylated, native human PAI-1.     

Tissue plasminogen activator and plasminogen activator inhibitor-1 in human choledochal bile

Fibrinolytic properties have been detected in animal and human gallbladder (GB) bile. Plasminogen activator inhibitor-1 (PAI-1) has been reported in greater concentration in GB stone bile and may be a nucleating factor in the pathogenesis of GB stone formation. It is unknown whether or not human choledochal bile has similar properties, which could have a role in choledocholithiasis. The aims of this study were to determine the presence of fibrinolytic properties of human choledochal bile and to compare those properties among normal, acalculous, and calculous-infected choledochal bile. Tissue plasminogen activator (t-PA) and PAI-1 of choledochal bile were measured by enzyme linked immunosorbent assay in patients with cholangitis due to acalculous bile duct obstructions (n = 9), choledocholithiasis with cholangitis (n = 20), and normal bile (n = 7). The t-PA concentration of choledochal bile was no different among the three groups (acalculous-infected bile, median 4.61 ng/ml, and calculous-infected bile, 4.61 ng/ml, versus normal bile, 7.33 ng/ml). PAI-1 was detected in choledochal bile in significantly greater concentrations in patients with acalculous cholangitis due to bile duct obstructions and choledocholithiasis with cholangitis (acalculous-infected bile, median 0.36 ng/ml, and calculous-infected bile, 0.1 ng/ml, versus normal bile, 0.02 ng/ml, p < 0.05), but the bile concentration of PAI-1 was no different between the acalculous and calculous-infected choledochal bile. Human choledochal bile possesses t-PA and PAI-1. PAI-1 was present in greater concentrations in both acalculous and calculous-infected choledochal bile. Increased levels of PAI-1 may be an epiphenomenon of cholangitis rather than a factor in the pathogenesis of choledocholithiasis.     

Vitronectin effects on recombinant plasminogen activator inhibitor-1: structural and functional analysis

Functionally active recombinant plasminogen activator inhibitor-1 (rPAI-1) has been purified from bacterial cells in the absence of any discrete binding protein. In the present study, vitronectin, which is known to stabilise the natural form of PAI-1, was evaluated for its effects on the activity and structure of rPAI-1. As assessed by PAI-1 activity assays, purified human vitronectin was shown to stabilise rPAI-1, by doubling its half-life at 25° and 37°C, and to enhance the activity of rPAI-1 in concentration-dependent fashion. Vitronectin also restored partial activity to a latent form of rPAI-1 prepared by a 72h incubation at 37°C. Fluorescence spectroscopy studies revealed that rPAI-1 in association with vitronectin displayed a higher tryptophan emission signal than the sum of the emissions of the individual components. These results suggest that vitronectin effects on rPAI-1 activity may result from specific conformational effects induced upon binding of the two proteins.     

Plasma tissue plasminogen activator and plasminogen activator inhibitor-1 levels in acute myocardial infarction

The cause of the circadian variation in the incidence of acute myocardial infarction (AMI) has not been identified. Tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) have opposing effects on thrombi. Hence, the extent of the clot, the size of the infarct and outcome of patients could depend on t-PA and PAI-1 levels. In an effort to elucidate the pathophysiologic basis of circadian variation of AMI, we investigated the presence of a possible corresponding circadian variation in the levels of endogenous t-PA and PAI-1 in patients diagnosed to have AMI and the effects of hypertension, diabetes and site of the infarct on these levels. We estimated the levels of t-PA and PAI-1 in platelet-poor plasma of 42 patients with AMI on admission, using the enzyme-linked immunosorbant assay. Although not statistically significant, patients having an AMI in the morning hours had the highest t-PA:PAI-1 ratio. The normal circadian variation in PAI-1 levels was lost in patients with AMI, probably due to the disease process. Also, the t-PA levels in hypertensive patients were significantly lower than in nonhypertensives. PAI-1 levels were also significantly lower in patients with anteroseptal than in inferior and anterolateral AMI. This relationship between the fibrinolytic potential and the site of infarction needs further study. Furthermore, t-PA levels on admission were significantly lower in survivors and may have a predictive value in determining the outcome.     

Tissue plasminogen activator and plasminogen activator inhibitor-1 levels in patients with acute paraquat intoxication

To investigate the effects of reactive oxygen species (ROS) on tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) plasma levels, and their possible implications on clinical outcome, we measured tPA and PAI-1 levels in 101 patients with acute paraquat (PQ) intoxication. The control group consisted of patients who ingested non-PQ pesticides during the same period. tPA and PAI-1 levels were higher in the PQ group than in the controls. PQ levels were significantly correlated with ingested amount, timelag to hospital, tPA level, and hospitalization duration. tPA levels were correlated with PAI-1, fibrin degradation product (FDP), and D-dimer. D-dimer levels were lower in the PQ group than in the controls. Univariate analysis indicated the following significant determinants of death: age, ingested amount, PQ level, timelag to hospital, serum creatinine, lipase, pH, pCO(2), HCO(3) (-), WBC, FDP, PAI-1, and tPA. However, multivariate analysis indicated that only PQ level was significant independent factor predicting death. In conclusion, tPA and PAI-1 levels were higher, while D-dimer levels were lower in the PQ group than in the controls, implying that ROS stimulate tPA and PAI-1, but PAI-1 activity overrides tPA activity in this setting. Decreased fibrinolytic activity appears to be one of the clinical characteristics of acute PQ intoxication.     

Monoclonal antibodies against a recombinant form of plasminogen activator inhibitor-1: Effects on tissue plasminogen activator neutralizing and vitronectin binding properties

A panel of eight murine monoclonal antibodies was produced against a recombinant form of plasminogen activator inhibitor- 1 (rPAI-1). All the antibodies recognized active and latent forms of rPAI-1, and rPAI-1 complexed with tissue plasminogen activator (t-PA) as determined in enzyme-linked immunosorbent assays (ELISA). Three of the antibodies, FAG9, FAD3 and BBH2, were particularly effective at inhibiting the t-PA neutralizing activity of rPAI-1 as measured in a chromogenic assay. Three different antibodies, DD8E9, FEG7 and FGG7, inhibited the binding of [¹²⁵I]rPAI-1 to vitronectin immobilized on polystyrene wells. The combination of FGG7 and alkaline phosphatase-labeled BBH2 resulted in a sensitive sandwich ELISA for rPAI-I with detection limits in the range of 1–10 ng. Definition of epitopes recognized by these antibodies will be useful for identifying various domains on PAI-1 involved in its interaction with protease substrates and with its protein cofactor, vitronectin.     

Expression of urokinase-type plasminogen activator, urokinase-type plasminogen activator receptor, and plasminogen activator inhibitor-1 and -2 in hepatocellular carcinoma

It has become more and more clear in recent decades that the plasminogen activation system, which includes urokinase-type plasminogen activator (uPA), urokinase-type plasminogen activator receptor (uPAR), plasminogen activator inhibitor (PAI)-1 and PAI-2, plays a very important role in the aggressiveness of cancer. Using immunohistochemistry and enzyme-linked immunosorbent assay (ELISA), the expression of these four components of the uPA system was analyzed in 19 cases of hepatocellular carcinoma (HCC) and 18 cases of the adjacent non-cancer tissues which all had chronic active hepatitis with liver fibrosis or liver cirrhosis. Four cases of normal liver tissues, as controls for immunohistochemical stains, were obtained from the hepatectomized liver of patients with metastatic cancer in the liver. The positive rates of uPA, uPAR, PAI-1 and PAI-2 for immunohistochemical stains in cancer tissues were 78.9, 68.4, 57.9 and 31.6%, respectively. Positive signals were mainly distributed in the cytoplasm of the cancer and in stromal cells. Moreover, the strong stains were chiefly located in the invasive front of the cancer cells. No specific stain was detected in four cases of normal liver tissues. In ELISA, there were significant differences between cancer and non-cancer tissues in concentration of uPA, uPAR and PAI-1 (P < 0.0003, 0.0024 and 0.01, respectively), but there was no significant difference in that of PAI-2 (P = 0.37). These results suggest that uPA, uPAR and PAI-1 are related to invasion of HCC.     

Studies on the interaction between plasminogen activator inhibitor-1 and vitronectin

Recently, the functionally active form of plasminogen activator inhibitor type-1 (PAI-1) was found to bind to vitronectin both in plasma and in extracellular matrix. In the present study the formation of the complex between functionally active PAI-1 and vitronectin has been studied using vitronectin-coated microtitre plates. PAW bound to vitronectin in the microtitre plates was quantified using HRP-conjugated monoclonal antibodies towards PAI-1. Even at PAI-I concentrations of about I pmol/I the binding to the vitronectin-coated plates seem to be quantitative suggesting high affinity. In contrast, with ‘latent’ PAI-1 at similar molar concentrations, no binding was observed. The effects of pH, NaCl, KBr, KSCN, urea, guanidinium chloride and certain amino acids were studied on the interaction between active PAI-1 and vitronectin. The interaction was not affected at a wide pH range or by increasing the ionic strength by addition of NaCl, suggesting that the binding is more complicated than just an ionic binding. In addition, no effect was observed on the complex formation by 2 mol/I KBr. In contrast, 0.5 mol KSCN almost completely abolished complex formation. Furthermore, arginine and guanidinium chloride, both dissociated the complex readily. Half maximal binding was obtained at about 0.3 mol/I for both substances. In contrast hardly any effect was obtained with epsilon aminocaproic acid (EACA) or lysine in concentrations up to 1.6 mol/I. Our results suggest that guanidine groups and most likely also hydrophobic interactions are involved in the binding of the active form of PAI-1 to vitronectin.     

人脐静脉内皮细胞分泌组织型纤溶酶原激活物及其抑制剂1对醒脑静干预的反应

背景：前期研究发现醒脑静能有效抑制兔心肌缺血再灌注模型的炎症递质及促纤溶作用,但是影响纤溶系统活性的作用机制未完全明确。目的：观察醒脑静对重组人肿瘤坏死因子α介导人脐静脉内皮细胞分泌组织型纤溶酶原激活物和纤溶酶原激活物抑制剂1及其基因表达的影响。方法：取3-5 代人脐静脉内皮细胞,在培养基中添加10 μg/L 重组人肿瘤坏死因子α介导人脐静脉内皮细胞分泌组织型纤溶酶原激活物和纤溶酶原激活物抑制剂1及其基因表达,醒脑静组加入不同浓度(5,10,20 mL/L)的醒脑静干预,阳性对照组添加氟伐他汀(1 μmol/L),并设立单纯人脐静脉内皮细胞培养的空白对照组。培育24 h后采用酶联免疫吸附双抗体夹心法(ELISA)检测细胞上清液组织型纤溶酶原激活物和纤溶酶原激活物抑制剂1水平;采用反转录聚合酶链反应检测人脐静脉内皮细胞的组织型纤溶酶原激活物和纤溶酶原激活物抑制剂1的mRNA表达。结果与结论：重组人肿瘤坏死因子α组纤溶酶原激活物抑制剂1分泌和mRNA表达较空白对照组显著升高 (P < 0.05),组织型纤溶酶原激活物分泌和mRNA表达较空白对照组显著降低(P < 0.05)。不同浓度醒脑静组纤溶酶原激活物抑制剂1分泌和mRNA表达均较重组人肿瘤坏死因子α组显著降低(P < 0.05),而组织型纤溶酶原激活物分泌和mRNA表达均较重组人肿瘤坏死因子α组显著升高(P < 0.05),且呈剂量依赖关系。结果证实,醒脑静作用可逆转重组人肿瘤坏死因子α所致的人脐静脉内皮细胞的纤溶活性。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

Extracellular and cell-associated localizations of plasminogen activators and plasminogen activator inhibitor-1 in cultured endothelium

The extracellular localizations of urokinase-type plasminogen activator (uPA), tissue-type plasminogen activator (tPA), and plasminogen activator inhibitor-1 (PAI-1) were examined in cultured bovine capillary endothelial cells (BCEs) by an immunofluorescence method using BCEs treated with or without saponin and focal contact preparations. The specific immunofluorescence of cell surface uPA showed a patchy or strand-like distribution and was colocalized with vinculin strands indicating that uPA secreted from BCEs was mainly deposited at the cell surface of focal contacts. BCEs at a subconfluent density showed a higher intensity of specific immunofluorescence for uPA than when they were at a confluent density. tPA was observed over the dorsal surface of cultured BCEs and accentuated at their margins, suggesting that tPA was diffusely distributed on the luminal surface of BCEs in vivo. PAI-1 was distributed in the extracellular matrix under cultured BCEs. These findings suggest that uPA and PAI-1 are located under BCEs participating in the regulation of proteolytic activities provoked by plasminogen-PAs-plasmin system in vivo. The localization of tPA appears to be consistent with its function, which is to maintain the fluidity of the blood and to initiate thrombolysis in vivo.     

Leading-edge myofibroblasts in human colon cancer express plasminogen activator inhibitor-1

Plasminogen activator inhibitor-1 (PAI-1) is up-regulated strongly in various cancer tissues, including colon cancer tissue. Highly specific rabbit polyclonal antibodies against PAI-1 were used for immunohistochemical localization of PAI-1 in 12 invasive colorectal adenocarcinomas. PAI-1 immunoreactivity was observed in endothelial cells of some vessels located in the submucosa and in several fibroblast-like cells located at the invasive front. No PAI-1 immunoreactivity was seen in cancer cells in any of the 12 cases. Double immunofluorescence using the PAI-1 antibodies together with antibodies against alpha-smooth muscle actin for myofibroblast/smooth muscle cells and CD34 for endothelial cells showed that more than 80% of the PAI-1-positive fibroblast-like cells in all 12 cases were myofibroblasts. In 4 of 12 cases, a few of the PAI-1-positive fibroblast-like cells in the invasive front were CD34+. We conclude that the majority of PAI-1-positive fibroblast-like cells located at the leading edge of the invasive colon cancers are myofibroblasts.     

糖基化终末产物对大鼠肾系膜细胞纤溶酶原激活物抑制物-1表达的影响

目的:观察糖基化终末产物(AGEs)对大鼠肾系膜细胞纤溶酶原激活物抑制物-1(PAI-1)表达的影响及其与细胞外基质(ECM)成分含量的关系。方法:体外培养正常大鼠肾系膜细胞,分别用糖化牛血清白蛋白(AGEs)及未经糖化的牛血清白蛋白(BSA)处理,以常规培养的肾系膜细胞作为对照,检测不同时间、不同浓度AGEs对纤维连接蛋白(FN)、Ⅳ型胶原、PAI-1表达的影响。MTT法检测AGEs对系膜细胞增殖的作用,ELISA测定条件培养基中FN、Ⅳ型胶原及PAI-1蛋白含量,逆转录聚合酶链式反应(RT-PCR)检测系膜细胞PAI-1mRNA的表达。结果:与相应浓度的BSA比较,AGEs(0-200mg/L)对系膜细胞增殖无明显影响,但可不同程度地刺激系膜细胞FN、Ⅳ型胶原、PAI-1蛋白的产生。RT-PCR检测显示,给予AGEs(100mg/L)的系膜细胞PAI-1mRNA的表达明显增加(P<0.01)。结论:AGEs促进系膜细胞PAI-1的表达,提示AGEs通过上调PAI-1的表达而减少细胞外基质降解,可能是糖尿病肾病细胞外基质积聚的原因之一。     

糖基化终末产物对大鼠肾系膜细胞纤溶酶原激活物抑制物-1表达韵影响

目的：观察糖基化终末产物（AGEs）对大鼠肾系膜细胞纤溶酶原激活物抑制物-1（PAI-1）表达的影响及其与细胞外基质（ECM）成分含量的关系。方法：体外培养正常大鼠肾系膜细胞，分别用糖化牛血清白蛋白（AGEs）及未经糖化的牛血清白蛋白（BSA）处理，以常规培养的肾系膜细胞作为对照，检测不同时间、不同浓度AGEs对纤维连接蛋白（FN）、Ⅳ型胶原、PAI-1表达的影响。MTT法检测AGEs对系膜细胞增殖的作用，ELISA测定条件培养基中FN、Ⅳ型胶原及PAI-1蛋白含量，逆转录聚合酶链式反应（RT—PCR）检测系膜细胞PAI-1 mRNA的表达。结果：与相应浓度的BSA比较，AGEs（0—200mg／L）对系膜细胞增殖无明显影响，但可不同程度地刺激系膜细胞FN、Ⅳ型胶原、PAI-1蛋白的产生。RT—PCR检测显示，给予AGEs（100mg／L）的系膜细胞PAI-1 mRNA的表达明显增加（P〈0．01）。结论：AGEs促进系膜细胞PAI—1的表达，提示AGEs通过上调PAI-1的表达而减少细胞外基质降解，可能是糖尿病肾病细胞外基质积聚的原因之一。     

甲基强的松龙对狼疮性肾炎患者血浆中PAI-1的影响

目的 :研究甲基强的松龙对Ⅳ型狼疮性肾炎 (LN)患者血浆中 1型纤溶酶原激活物抑制物 (PAI 1)的影响。方法 :应用免疫组织化学ELISA方法检测患者血浆中PAI 1含量。结果 :①LN治疗组与对照组比较 (P <0 0 1) ;②LN患者经甲基强的松龙两次冲击治疗后与治疗前分别比较 (P <0 .0 1) ;③甲基强的松龙第二次冲击治疗后 ,与对照组比较无显著性差异 (P >0 0 5 )。结论 :甲基强的松龙通过干扰纤溶酶原激活物 (PA) 纤溶酶系统 ,使LN病人血浆中PAI 1含量明显降低 ,从而发挥治疗作用。     

Cerebrospinal fluid plasminogen activator inhibitor-1 in patients with neurological disease.

AIM: To study cerebrospinal fluid (CSF) concentrations of plasminogen activator inhibitor type-1 (PAI-1) in patients with neurological disease. METHODS: CSF PAI-1 concentrations were measured in 51 patients with neurological disease and 20 reference subjects using an ELISA. The patient group comprised three patients with viral meningitis, 20 with encephalitis, nine with acute lymphoblastic (n = 7) and myeloid (n = 2) leukaemia (with central nervous system involvement), and 19 with multiple sclerosis. RESULTS: Raised PAI-1 concentrations were observed in patients with leukaemia, encephalitis and multiple sclerosis. There was no difference in the mean concentrations of PAI-1 in patients with meningitis when compared with the reference subjects. The highest mean (SEM) PAI-1 concentration was found in patients with leukaemia (1.28 (0.36) ng/ml), and the next highest in those with encephalitis (1.19 (0.20) ng/ml). these values were much higher than those in patients with viral meningitis. In a previous report, raised CSF tissue-type plasminogen activator (tPA) activities were detected in patients with multiple sclerosis, leukaemia and encephalitis, with mean activities in decreasing order. PAI-1 concentrations in the same patients were the reverse of their corresponding tPA activities, being higher in those with leukaemia and encephalitis, than in patients with multiple sclerosis. There was no association between CSF PAI-1 concentrations and age in either patients or controls. Similarly, there was no association between CSF PAI-1 concentrations and urokinase-type plasminogen activator (uPA). CONCLUSIONS: Raised CSF PAI-1 concentrations may be used as a non-specific marker of neurological disease. Moreover, PAI-1 may play an important role in regulating the functions tPA, and probably uPA, in CSF.     

Oxidative stress and hypoxia: implications for plasminogen activator inhibitor-1 expression

Plasminogen activator inhibitor-1 (PAI-1) is the major physiological inhibitor of urokinase-type and tissue-type plasminogen activators. It has gained special interest among clinicians because a number of pathological conditions, such as myocardial infarction, atherosclerosis, thrombosis, several types of cancer, and the metabolic syndrome, as well as type 2 diabetes mellitus, are associated with increased PAI-1 levels. Interestingly, a number of these diseases are also accompanied by oxidative stress and the enhanced production of reactive oxygen species or tissue hypoxia. This article tries to summarize some aspects leading to enhanced PAI-1 production under oxidative stress or hypoxia.     

Dexamethasone-induced plasminogen activator inhibitor-1 expression in human primary bone marrow adipocytes

Several studies have demonstrated the association of plasminogen activator inhibitor-1 (PAI-1) with osteonecrosis, but the underlying mechanism of osteonecrosis and its relationship with local PAI-1 is not clear. The objective of this study was to evaluate PAI-1 production by primary human bone marrow adipocytes and the effects of glucocorticoid administration. Bone marrow was obtained from 25 individuals during prosthetic insertion. Mature adipocytes were cultured for 24 h with or without dexamethasone. PAI-1, adiponectin, tumor necrosing factor-α (TNFα) expression were measured by latex photometric immunoassay or RT-PCR. Adiponectin, TNFα and PAI-1 were detected in all culture media. PAI-1 expression was significantly increased by treatment with 10(-6) mol/L dexamethasone up to 24 h in protein and mRNA levels, while the levels of other adipokines did not change by dexamethasone. These results suggest that bone marrow adipocytes may play important roles for the development of glucocorticoid-induced osteonecrotic diseases by enhancing PAI-1 expression.     

Acute psychological stress decreases plasma tissue plasminogen activator (tPA) and tissue plasminogen activator/plasminogen activator inhibitor-1 (tPA/PAI-1) complexes in cardiac patients

Tissue plasminogen activator (tPA) promotes fibrinolysis, and impaired fibrinolysis is associated with atherosclerosis and thrombosis. Plasminogen activator inhibitor-1 (PAI-1) inhibits t-PA expression. The effects of acute laboratory stressors on tPA and tPA/PAI-1 complexes were assessed in a sample of 11 cardiac patients. Participants were randomly assigned to either a stress or relaxation condition at time 1, and the alternative condition at time 2. Blood samples were taken before (pre) and after (post) each session and participants completed a battery of psychological questionnaires. Two-way repeated-measures analysis of variance revealed a statistically significant decrease in tPA (P=0.01) and tPA-PAI-1 complexes (P=0.04) during the mental stress condition. Anger-in had a strong relationship to decreases in tPA/PAI-1 levels in the stress condition (r=0.68, P?<?0.05). Relaxation had no significant effect on tPA and tPA/PAI-1 levels. These data suggest that decreased fibrinolysis mediates the relationship between mental stress and atherosclerosis.