Association of plasminogen activator inhibitor-1 with insulin resistance in Japan where obesity is rare

The association between plasminogen activator inhibitor-1 (PAI-1) and insulin resistance is established in western countries. The major component of this association is obesity. Accordingly, we examined this association in Japan where the prevalence of obesity is low. Data for fasting PAI-1 levels of 404 subjects were obtained from a general population in a farming area. We measured body mass index (BMI), systolic and diastolic blood pressure, high-density lipoprotein (HDL)-cholesterol, triglycerides, fasting plasma glucose (FPG), insulin, creatinine, and uric acid. The use of alcohol was ascertained by a questionnaire. The formula for the homeostasis model assessment (HOMA) score was used as an index of insulin resistance. Uni- and multivariate analyses were applied for the determinants of plasma PAI-1. Age and sex did not affect plasma PAI-1. The average BMI was 23.0 +/- 3.2 kg/m(2). Thus, most of the subjects were not obese. Because, even in this population, BMI (P <.001) was the strongest determinant for PAI-1 after univariate analysis, we performed multiple linear regression analyses after adjustment for BMI. The significance of triglycerides, FPG, insulin, and the HOMA score still remained. PAI-1 levels were linearly related to the HOMA score. From the subanalysis of the non-obese subjects (BMI < 25; n = 298), waist-hip ratio, triglycerides, FPG, and HOMA scores were significant determinants of PAI-1. This is the first demonstration that increased PAI-1 levels were significantly related to insulin resistance in a Japanese general population. PAI-1 levels are associated with insulin resistance, irrespective of obesity.     

Obesity and impaired fibrinolysis: role of adipose production of plasminogen activator inhibitor-1

Obesity is the central promoter of the metabolic syndrome which also includes disturbed fibrinolysis in addition to hypertension, dyslipidaemia and impaired glucose tolerance/type 2 diabetes mellitus. Plasminogen activator inhibitor-1 (PAI-1) is the most important endogenous inhibitor of tissue plasminogen activator and uro-plasminogen activator, and is a main determinant of fibrinolytic activity. There is now compelling evidence that obesity and, in particular, an abdominal type of body fat distribution are associated with elevated PAI-1 antigen and activity levels. Recent studies established that PAI-1 is expressed in adipose tissue. The greater the fat cell size and the adipose tissue mass, the greater is the contribution of adipose production to circulating PAI-1. Experimental data show that visceral adipose tissue has a higher capacity to produce PAI-1 than subcutaneous adipose tissue. Studies in human adipocytes indicate that PAI-1 synthesis is upregulated by insulin, glucocorticoids, angiotensin II, some fatty acids and, most potently, by cytokines such as tumour necrosis factor-alpha and transforming growth factor-beta, whereas catecholamines reduce PAI-1 production. Interestingly, pharmacological agents such as thiazolidinediones, metformin and AT(1)-receptor antagonists were found to reduce adipose expression of PAI-1. In addition, weight loss by dietary restriction or comprehensive lifestyle modification is effective in lowering PAI-1 plasma levels. In conclusion, impaired fibrinolysis in obesity is probably also due to an increased expression of PAI-1 in adipose tissue. An altered function of the endocrine system and an impaired auto-/paracrine function at the fat cell levels may mediate this disturbance of the fibrinolytic system and thereby increase the risk for cardiovascular disease..     

Developmental expression of plasminogen activator inhibitor-1 associated with thrombopoietin-dependent megakaryocytic differentiation.

Plasminogen activator inhibitor-1 (PAI-1) is present in the platelet alpha-granule and is released on activation. However, there is some debate as to whether the megakaryocyte and platelet synthesize PAI-1, take it up from plasma, or both. We examined the expression of PAI-1 in differentiating megakaryocytic progenitor cells (UT-7) and in CD34(+)/CD41(-) cells from cord blood. UT-7 cells differentiated with thrombopoietin (TPO) resembled megakaryocytes (UT-7/TPO) with respect to morphology, ploidy, and the expression of glycoprotein IIb-IIIa. PAI-1 messenger RNA (mRNA) expression was upregulated and PAI-1 protein synthesized in the UT-7/TPO cells accumulated in the cytoplasm without being released spontaneously. In contrast, erythropoietin (EPO)-stimulated UT-7 cells (UT-7/EPO) did not express PAI-1 mRNA after stimulation with TPO because they do not have endogenous c-Mpl. After cotransfection with human wild-type c-mpl, the cells (UT-7/EPO-MPL) responded to phorbol 12-myristate 13-acetate (PMA), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) with enhanced PAI-1 mRNA expression within 24 to 48 hours. However, induction of PAI-1 mRNA in UT-7/EPO-MPL cells by TPO required at least 14-days stimulation. UT-7/EPO cells expressing c-Mpl changed their morphology and the other characteristics similar to the UT-7/TPO cells. TPO also differentiated human cord blood CD34(+)/CD41(-) cells to CD34(-)/CD41(+) cells, generated morphologically mature megakaryocytes, and induced the expression of PAI-1 mRNA. These results suggest that both PAI-1 mRNA and de novo PAI-1 protein synthesis is induced after differentiation of immature progenitor cells into megakaryocytes by TPO.     

Gene polymorphisms of tissue plasminogen activator and plasminogen activator inhibitor-1 in patients with antiphospholipid antibodies

OBJECTIVE: Impaired fibrinolytical outcomes may be one of the pathogenic factors for thrombotic events in patients with antiphospholipid antibodies (aPL). We investigated the consequences of the gene polymorphisms of tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) in patients positive for aPL. METHODS: Seventy-seven Japanese and 82 British patients with aPL were examined for Alu-repeat insertion (I)/deletion (D) polymorphism of the tPA gene by polymerase chain reaction (PCR), and 4G/5G polymorphism in the PAI-1 promoter gene by site-directed mutagenesis-PCR and restriction fragment length polymorphism analysis. Correlations between these polymorphisms and clinical symptoms of antiphospholipid syndrome (APS) (arterial thrombosis, venous thrombosis, miscarriage) were analyzed. RESULTS: Significant differences in the allele frequencies of these genes did not exist between patients and controls. There was no significant correlation between these gene polymorphisms and clinical symptoms of APS in patients with aPL. CONCLUSION: Polymorphisms of the tPA or PAI-1 genes probably do not significantly influence the risk of anerial thrombosis, venous thrombosis, or pregnancy morbidity in patients with aPL.     

Expression of urokinase-type plasminogen activator receptor and plasminogen activator inhibitor-1 in gastric cancer

In gastric cancer, the urokinase-type plasminogen activator (uPA) system plays important roles in invasion and metastasis, processes which entail proteolysis and adhesion. Both the urokinasetype plasminogen activator receptor (uPAR) and the plasminogen activator inhibitor-1 (PAI-1) are thought to be important factors in this system. To clarify the relationship between these two factors and gastric cancer invasiveness, we evaluated the expression of uPAR and PAI-1 in 91 cases of gastric cancer by immunohistochemistry and in situ hybridization. Urokinase-type plasminogen activator receptor-mRNA, PAI-1-mRNA, uPAR and PAI-1 protein were diffusely distributed in the cytoplasm of the cancer cells and concentrated at invasive foci. Urokinase-type plasminogen activator receptor protein expression correlated with lymphatic, venous invasion (P<.01) and lymph node metastasis (P<0.05); uPAR-mRNA expression correlated with lymphatic, venous invasion and lymph node metastasis (P<0.05). Plasminogen activator inhibitor-1 protein expression correlated with lymphatic, venous invasion, lymph node metastasis and depth of invasion (P<0.01); PAI-1-mRNA expression was linked to lymphatic, venous invasion (P<0.01), lymph node metastasis and depth of invasion (P<0.05). This suggests that the proteolytic activity of uPAR and the cellular motility of PAI-1 in gastric cancer cells may determine penetration of lymphatic and blood vessels, whereby lymph node metastasis may be promoted and that the promotion of cellular motility by PAI-1 may influence the depth of cancer invasion.     

Detection of impaired fibrinolytic activity in coronary artery disease--electrophoretic and immuno-blotting analysis of tissue plasminogen activator

In present study, we investigated the fibrinolytic activities and plasma antigen levels of tissue plasminogen activator (tPA) before or after a submaximal exercise in patients with coronary artery disease (CAD). We also investigated tPA phenotypes in plasma by electrophoretic and immuno-blotting analysis. Euglobulin fractions obtained from plasma were submitted to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting analysis. There were no differences in plasma antigen levels of tPA between the study group and controls before or after the exercise, however CAD patients showed lower fibrinolytic activities after the exercise than controls. SDS-PAGE followed by immuno-blotting with an antisera against human tPA revealed two bands at molecular weights (m.w.) of 70,000 and 120,000. The band at m.w. of 70,000 corresponded to free tPA and that of 120,000 was considered to be identical to a complex of tPA with its inhibitor. Furthermore, we found a decrease in free tPA in the patients with low fibrinolytic activities. From these results it was concluded that impaired fibrinolytic activities, probably due to decreased free tPA, observed in CAD patients, might be an important factor in the pathogenesis of CAD.     

Epicardial fat thickness: relationship with plasma visfatin and plasminogen activator inhibitor-1 levels in visceral obesity

Background and aimEpicardial fat (EF), a true visceral adipose tissue (VAT) deposited around the heart, is considered as possible cardiovascular risk indicator, in view of its ability to produce and release several inflammatory adipo-cytokines. It is still not known whether increased cardiac adiposity is related to increased inflammatory adipo-cytokines in obesity. The aim of this study was to evaluate whether echocardiographic EF thickness, an indicator of cardiac adiposity, is related to circulating levels of inflammatory adipo-cytokines such as visfatin and plasminogen activator inhibitor-1 (PAI-1) in visceral obesity.Methods and resultsEF thickness (measured by echocardiography), visfatin, PAI-1 antigen and some inflammatory markers were studied in 42 women, 27 of them severely obese (OB) (BMI 43.5 ± 4.8 kg/m²) but with no apparent complications, and 15 normal-weight controls. Abdominal VAT in the OB was assessed by computed tomography. OB had thicker EF and higher visfatin and PAI-1 antigen concentrations than controls (P < 0.0001). EF thickness, log-visfatin and log-PAI-1 antigen concentrations directly correlated with VAT (P < 0.0001). Log-visfatin and log-PAI-1 antigen were correlated with EF thickness even after adjusting for indices of fat distribution (P < 0.01 and P < 0.001 respectively). Moreover, when dividing OB on the basis of median EF thickness, women with greater EF thickness had more VAT and higher adipo-cytokine concentrations and inflammatory markers.ConclusionsThis study suggests that EF thickness, an indicator of cardiac adiposity, may be significantly related to inflammatory adipo-cytokines in visceral-obese patients. This suggests EF might be used as an easy and reliable marker of visceral adiposity and inflammation and as a cardiovascular risk indicator.     

老年糖尿病PAI-1与IR的相关性分析

目的探讨老年糖尿病患者血浆纤溶酶原激活物抑制物-1(PAI-1)活性及基因启动子区4G/5G多态性与胰岛素抵抗(IR)的关系。方法运用等位基因特异性PCR扩增技术对136例老年糖尿病患者PAI-14G/5G多态位点的基因型进行检测,发色底物法测血浆PAI-1活性。结果1老年糖尿病患者血浆PAI-1活性明显升高,空腹胰岛素(FPG)、胰岛素抵抗指数(HOMA-IR)、体重指数(BMI)、4G/5G基因类型与PAI-1活性升高密切相关(P<0.05)。2对照组和伴IR的糖尿病患者的4G/4G基因型频率分别为47.2%和32,5%,两组比较无明显差异(P>0.05),IR组不同基因型患者的PAI-1活性差异显著(P<0.01),4G/4G型者PAI-1活性明显高于4G/5G和5G/5G者(P<0.05)。3胰岛素对PAI-1活性的影响无基因依赖性。结论老年糖尿病患者PAI-1活性升高,FPG、HOMA-IR、BMI与PAI-1活性升高有关,甘油三酯对PAI-1活性的调节存在基因型依赖性。     

纤溶酶原激活物抑制物在纤维化肝组织中的表达及其血浆活性检测

目的 研究和探讨纤溶酶原激活物抑制物（ｐｌａｓｍｉｎｏｇｅｎ ａｃｔｉｖａｔｏｒ ｉｎｈｉｂｉｔｏｒ－１,ＰＡＩ－１）在人肝纤维化组织中分布、作用及血浆中活性水平的变化。方法 采用原位杂交和免疫组织化学方法检测正常人,慢性乙型肝炎及肝硬化患者肝组织中ＰＡＩ－１ｍＲＮＡ和蛋白表达,并对蛋白表达的半定量结果与肝纤维化程度进行对比分析。同时采用发色７底物法检测血浆中ＰＡＩ－１活性。结果 随肝纤维化程度的     

In young post-myocardial infarction male patients elevated plasminogen activator inhibitor-1 correlates with insulin resistance and endothelial dysfunction

Classical and nonclassical risk factors contribute to the development of myocardial infarction (MI) in young patients. The aim of the present study was to find out whether insulin resistance and impaired fibrinolysis, with increased plasminogen activator inhibitor (PAI-1), are present in young male post-MI patients, and their relation to additional markers of cardiovascular risk such as endothelial dysfunction (ED) and intima-media thickness (IMT). Forty-one male patients (on average 44 years old) in the stable phase after MI were recruited, with 25 healthy males who did not differ from patients regarding age as controls. Body mass index (BMI) and waist-to-hip ratio were measured and insulin resistance was calculated. Several coagulation/fibrinolytic parameters and inflammation markers were measured. ED was estimated by ultrasound measurement of the flow-mediated dilatation (FMD) of the brachial artery, and IMT was measured on the common carotid artery. BMI was increased in post-MI patients in comparison with healthy controls. Compared with the control group, in post-MI patients PAI-1 antigen (13.8 ± 10.6 vs 9.1 ± 7.6 ng/ml, P = 0.042), PAI-1 activity (14.8 ± 10.8 vs 9.0 ± 8.0 IU/ml, P = 0.015), and fibrinogen were significantly elevated. In patients increased PAI-1, antigen and activity were both significantly positively related to insulin resistance. We found an important negative relation between PAI-1 antigen and FMD (r = ?0.32, P = 0.04) and between PAI-1 activity and FMD (r = ?0.39, P = 0.01). Our results suggest that PAI-1 can be a link between obesity, insulin resistance, and MI in young patients. It is thus concluded that impaired fibrinolysis with increased PAI-1 may be an important nonclassical risk factor for MI, particularly in young males with increased BMI and insulin resistance.     

Tissue plasminogen activator,plasminogen activator inhibitor-1 and von willebrand factor in rheumatoid arthritis

Summary Tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) and von Willebrand factor (vWF), all of endothelial origin and active in the haemostasis, were analysed in 74 patients with rheumatoid arthritis. The concentrations were related to extra-articular disease and to the incidence of thromboembolic events (TE) registered in a 2-year follow-up period. Patients with extra-articular disease had a significant increase in PAI-1 activity and reduced tPA release in the venous occlusion test. von Willebrand factor, PAI-1 and also haptoglobin and triglycerides were significantly increased in the group of patients who later suffered from TE. In a multiple regression model, in which cholesterol, triglycerides and lipoprotein (a) showed significant association with TE, vWF had the strongest additive explanatory value. No distinct acute phase pattern of PAI-1 was found in any patient subgroup.     

纤溶酶原激活剂抑制物的基因多态性与狼疮性肾炎肾小球的微血栓

目的：探讨纤溶酶原激活剂抑制物－1（PAI－1）基因启动子区－675bp4G/5G多态性与狼疮性肾炎（LN）肾小球微血栓形成的关系。方法：选取101例LN患者，所有患者均行经皮肾活检。其中46例患者伴有肾小球毛细血管袢内微血栓（T组），55例患者不伴血栓（non-T组）。应用PCR－SLP法分析基因型。同时收集肾活检时各患者的临床资料。正常对照组包括128名健康成人。结果：①T组血清肌酐（SCr)水平显著高于non-T组，蛋白尿和血尿也较non-T组严重；但两组间血清抗心磷脂抗体阳性率无差异；②PAI－I基因4G／4G基因型及4G型等位基因与T组显著相关；LN中4G／4G型患者形成袢内血栓的相对风险率为OR＝2．96，95％CI：1．26－6．92。结论：LN肾小球微血栓的形成与PAI－I基因4G／5G多态性密切相关。     

Impaired fibrinolytic compensation for hypercoagulability in obese patients with type 2 diabetes: association with increased plasminogen activator inhibitor-1

In patients with type 2 diabetes, fibrinolysis is considered impaired by increased plasma concentrations of plasminogen activator inhibitor (PAI)-1. However, several investigators found both coagulation and fibrinolysis to be activated in these patients. We further characterized the balance between coagulation and fibrinolysis in lean and obese patients with type 2 diabetes. We studied 112 type 2 diabetic patients (66 lean, 46 obese) and 69 age-matched healthy subjects (46 lean, 23 obese). We measured plasma concentrations of fibrinogen and prothrombin F1+2 (F1+2) as indicating coagulation activity and plasmin-antiplasmin complex (PAP) and D dimer as indicating fibrinolytic activity. Plasma PAI-1 concentrations also were determined. Plasma concentrations of F1+2, PAP, D dimer, and PAI-1 were higher in diabetic patients than in control subjects. Plasma fibrinogen and F1+2 were similar between lean and obese diabetic patients, but plasma PAP and D dimer were significantly lower in obese than lean diabetic patients (P <.0001, P =.0194, respectively). By multivariate analysis, plasma PAI-1 and body mass index (BMI) were independent factors in diabetic patients predicting PAP, while BMI and glycosylated hemoglobin (HbA(1c)) independently predicted D dimer. Plasma PAI-1 concentrations were significantly higher in obese than lean diabetic patients (P <.0001). In conclusions, both coagulation and fibrinolytic systems are enhanced in lean and obese type 2 diabetic patients compared with healthy subjects. Although the degree of activation of coagulation was similar between lean and obese diabetic patients, the fibrinolytic activity was lower in obese than lean patients. Fibrinolytic compensation for hypercoagulation is incomplete in obese patients with type 2 diabetes, partly because of elevated PAI-1 in the blood.     

Studies of recombinant plasminogen activator inhibitor-1 in rabbits. Pharmacokinetics and evidence for reactivation of latent plasminogen activator inhibitor-1 in vivo

The pharmacokinetics of human recombinant plasminogen activator inhibitor-1 (rPAI-1) was studied in rabbits. Latent rPAI-1 (0-2 units of tissue-type plasminogen activator neutralizing activity per microgram protein); reactivated rPAI-1 (approximately 150 units/micrograms); and chloramine T-oxidized, nonreactivatable rPAI-1 (approximately 0.7 units/microgram) were studied. The pharmacokinetic parameters for the disposition of rPAI-1 antigen after an intravenous bolus injection of 1.0 or 2.5 mg/kg rPAI-1 were very similar for all three forms: the initial volume of distribution was approximately 60 ml/kg, the initial half-life in plasma was 6 minutes, and the plasma clearance was approximately 4 ml/kg/min. The disposition of PAI activity after injection of reactivated rPAI-1 was similar to that of rPAI-1 antigen. Injection of latent rPAI-1 was associated with a nearly threefold increase in the specific activity of circulating PAI-1 from 2 units/micrograms to 5.0 +/- 1.1 units/micrograms (p less than 0.01) within 1 minute, followed by a cumulative 25-fold increase in specific activity over 1 hour (p = 0.01). In contrast, the specific activity of oxidized or reactivated preparations of rPAI-1 did not increase in the first several minutes after injection. These findings support the existence of a fast-acting but low-capacity mechanism for the reactivation of rPAI-1 in vivo.