Function Of Plasminogen Activator Inhibitor-1 Research Articles

Pharmacological inhibition of plasminogen activator inhibitor-1 prevents memory deficits and reduces neuropathology in APP/PS1 mice.

Extracellular proteolytic activity plays an important role in memory formation and the preservation of cognitive function. Previous studies have shown increased levels of plasminogen activator inhibitor-1 (PAI-1) in the brain of mouse models of Alzheimer's disease (AD) and plasma of AD patients, associated with memory and cognitive decline; however, the exact function of PAI-1 in AD onset and progression is largely unclear. In this study, we evaluated a novel PAI-1 inhibitor, TM5A15, on its ability to prevent or reverse memory deficits and decrease Aβ levels and plaque deposition in APP/PS1 mice. We administered TM5A15 mixed in a chow diet to 3-month and 9-month-old APP/PS1 mice before and after neuropathological changes were distinguishable. We then evaluated the effects of TM5A15 on memory function and neuropathology at 9 months and 18 months of age. In the younger mice, 6 months of TM5A15 treatment protected against recognition and short-term working memory impairment. TM5A15 also decreased oligomer levels and amyloid plaques, and increased mBDNF expression in APP/PS1 mice at 9 months of age. In aged mice, 9 months of TM5A15 treatment did not significantly improve memory function nor decrease amyloid plaques. However, TM5A15 treatment showed a trend in decreasing oligomer levels in APP/PS1 mice at 18 months of age. Our results suggest that PAI-1 inhibition could improve memory function and reduce the accumulation of amyloid levels in APP/PS1 mice. Such effects are more prominent when TM5A15 is administered before advanced AD pathology and memory deficits occur.

Plasminogen Activator Inhibitor-1 Potentiates Neutrophil Infiltration and Tissue Injury in Colitis.

The mechanism underlying inflammatory bowel disease (IBD) remains unclear. We aimed to identify early diagnostic biomarkers and understand their roles in the pathogenesis of IBD. Methods: We identified plasminogen activator inhibitor-1 (PAI-1) as a potential key gene that is upregulated in IBD based on published transcriptomic datasets. To further determine the role of PAI-1 in disease pathogenesis, we induced colitis in wild-type (WT) and PAI-1 knockout (KO) mice by administering dextran sulfate sodium (DSS). We used an RNA array of genes and 16S rRNA sequencing of the microbiome to analyze PAI-1 function. The colon and serum PAI-1 levels in humans were further evaluated for their diagnostic value. Results: PAI-1 expression was significantly increased in patients and DSS-induced WT mice but reduced in PAI-1 KO mice. These changes were associated with significantly decreased neutrophil infiltration in colonic tissues. The RNA array revealed that the CXC chemokines CXCL1 and CXCL5 and their common receptor CXCR2 were among the most significantly different genes between the PAI-1 KO mice with DSS-induced colitis and the WT mice. Mechanistically, PAI-1 deficiency led to blunted activation of the NF-κB pathway in the colon epithelium. The gut microbiome was altered in the PAI-1 KO mice, which showed enriched abundances of short-chain fatty acid-producing genera and diminished abundances of pathogenic genera. Receiver operating characteristic (ROC) curve analysis revealed the diagnostic value of PAI-1. Conclusions: Our data suggest a previously unknown function of PAI-1 inducing neutrophil-mediated chemokine expression by activating the NF-κB pathway and affecting the function of the gut microbiome. PAI-1 could be a potential diagnostic biomarker and a therapeutic target in IBD.

PAI-1 is a potential transcriptional silencer that supports bladder cancer cell activity

The extracellular activity of Plasminogen activator inhibitor-1 (PAI-1) is well described, acting as an inhibitor of tissue plasminogen activator and urokinase-type plasminogen activator, impacting fibrinolysis. Recent studies have revealed a pro-tumorigenic role of PAI-1 in human cancers, via the regulation of angiogenesis and tumor cell survival. In this study, immunohistochemical staining of 939 human bladder cancer specimens showed that PAI-1 expression levels correlated with tumor grade, tumor stage and overall survival. The typical subcellular localization of PAI-1 is cytoplasmic, but in approximately a quarter of the cases, PAI-1 was observed to be localized to both the tumor cell cytoplasm and the nucleus. To investigate the potential function of nuclear PAI-1 in tumor biology we applied chromatin immunoprecipitation (ChIP)-sequencing, gene expression profiling, and rapid immunoprecipitation mass spectrometry to a pair of bladder cancer cell lines. ChIP-sequencing revealed that PAI-1 can bind DNA at distal intergenic regions, suggesting a role as a transcriptional coregulator. The downregulation of PAI-1 in bladder cancer cell lines caused the upregulation of numerous genes, and the integration of ChIP-sequence and RNA-sequence data identified 57 candidate genes subject to PAI-1 regulation. Taken together, the data suggest that nuclear PAI-1 can influence gene expression programs and support malignancy.

A Serpin With a Finger in Many PAIs: PAI-1's Central Function in Thromboinflammation and Cardiovascular Disease.

Plasminogen activator inhibitor 1 (PAI-1) is a member of the serine protease inhibitor (serpin) superfamily. PAI-1 is the principal inhibitor of the plasminogen activators, tissue plasminogen activator (tPA), and urokinase-type plasminogen activator (uPA). Turbulence in the levels of PAI-1 tilts the balance of the hemostatic system resulting in bleeding or thrombotic complications. Not surprisingly, there is strong evidence that documents the role of PAI-1 in cardiovascular disease. The more recent uncovering of the coalition between the hemostatic and inflammatory pathways has exposed a distinct role for PAI-1. The storm of proinflammatory cytokines liberated during inflammation, including IL-6 and TNF-α, directly influence PAI-1 synthesis and increase circulating levels of this serpin. Consequently, elevated levels of PAI-1 are commonplace during infection and are frequently associated with a hypofibrinolytic state and thrombotic complications. Elevated PAI-1 levels are also a feature of metabolic syndrome, which is defined by a cluster of abnormalities including obesity, type 2 diabetes, hypertension, and elevated triglyceride. Metabolic syndrome is in itself defined as a proinflammatory state associated with elevated levels of cytokines. In addition, insulin has a direct impact on PAI-1 synthesis bridging these pathways. This review describes the key physiological functions of PAI-1 and how these become perturbed during disease processes. We focus on the direct relationship between PAI-1 and inflammation and the repercussion in terms of an ensuing hypofibrinolytic state and thromboembolic complications. Collectively, these observations strengthen the utility of PAI-1 as a viable drug target for the treatment of various diseases.

A Narrative Review on Plasminogen Activator Inhibitor-1 and Its (Patho)Physiological Role: To Target or Not to Target?

Plasminogen activator inhibitor-1 (PAI-1) is the main physiological inhibitor of plasminogen activators (PAs) and is therefore an important inhibitor of the plasminogen/plasmin system. Being the fast-acting inhibitor of tissue-type PA (tPA), PAI-1 primarily attenuates fibrinolysis. Through inhibition of urokinase-type PA (uPA) and interaction with biological ligands such as vitronectin and cell-surface receptors, the function of PAI-1 extends to pericellular proteolysis, tissue remodeling and other processes including cell migration. This review aims at providing a general overview of the properties of PAI-1 and the role it plays in many biological processes and touches upon the possible use of PAI-1 inhibitors as therapeutics.

MiR145-5p inhibits proliferation of PMVECs via PAI-1 in experimental hepatopulmonary syndrome rat pulmonary microvascular hyperplasia.

ABSTRACTHepatopulmonary syndrome (HPS) is a triad of advanced liver disease, intrapulmonary vasodilatation and arterial hypoxemia. Increasing evidence shows that HPS is associated with pulmonary microvascular hyperplasia. The aim of this work was to investigate the underlying mechanism of miR-145 in regulating the proliferation of pulmonary microvascular endothelial cells (PMVECs) and angiogenesis in HPS via plasminogen activator inhibitor-1 (PAI-1). To test this, morphology score and number of pulmonary microvascular were assessed in lung tissues from rats with HPS by Hematoxylin and Eosin (H&E) staining. Expression levels of PAI-1 were assessed in lung tissues from HPS rats, as well as in PMVECs treated with HPS rat serum. We also selected the putative microRNA binding site on PAI-1 by bioinformatics analysis. Then, miR145-3p and miR145-5p expression levels in the lungs and PMVECs of rats were detected by qRT-PCR because miR145-5p is a microRNA binding site on PAI-1. In addition, the effects of miR-145-5p regulation on PAI-1 were examined by upregulation and downregulation of miR-145-5p and specific lentivirus transfection was used to overexpress and knockdown PAI-1 to assess PAI-1 function on PMVECs proliferation. Our data showed that levels of PAI-1 expression in lung tissue of rats increased significantly when rats were treated with common bile duct ligation. We found that levels of miR-145-5p were frequently downregulated in HPS tissues and cell lines, and overexpression of miR-145-5p dramatically inhibited PMVECs proliferation. We further verified PAI-1 as a novel and direct target of miR-145-5p in HPS. MiR-145-5p inhibits PAI-1 synthesis and the expression changes of PAI-1 directly affect the proliferation of PMVECs. We concluded that miR-145-5p negatively regulates PMVEC proliferation through PAI-1 expression. In addition, overexpression of miR-145-5p may prove beneficial as a therapeutic strategy for HPS treatment.

Plasminogen Activator Inhibitor-1 Promotes the Recruitment and Polarization of Macrophages in Cancer

Plasminogen activator inhibitor-1 (PAI-1) has a pro-tumorigenic function via its pro-angiogenic and anti-apoptotic activities. Here, we demonstrate that PAI-1 promotes the recruitment and M2 polarization of monocytes/macrophages through different structural domains. Its LRP1 interacting domain regulated macrophage migration, while its C-terminal uPA interacting domain promoted M2 macrophage polarization through activation of p38MAPK and nuclear factor κB (NF-κB) and induction of an autocrine interleukin (IL)-6/STAT3 activation pathway. We then show in several experiments in mice that expression of PAI-1 is associated with increased tumorigenicity, increased presence of M2 macrophages, higher levels of IL-6, and increased STAT3 phosphorylation in macrophages. Strong positive correlations between PAI-1, IL-6, and CD163 (M2 marker) expression were also found by meta-analysis of transcriptome data in many human cancers. Altogether, these data provide evidence for a mechanism explaining the paradoxical pro-tumorigenic function of PAI-1 in cancer.

Inhibition of Plasminogen Activator Inhibitor 1 Attenuates Hepatic Steatosis but Does Not Prevent Progressive Nonalcoholic Steatohepatitis in Mice.

Plasminogen activator inhibitor 1 (PAI‐1), an essential regulator of fibrinolysis, is increasingly implicated in the pathogenesis of metabolic disorders, such as obesity and nonalcoholic fatty liver disease (NAFLD). Pharmacologic inhibition of PAI‐1 is emerging as a highly promising therapeutic strategy for obesity and its sequelae. Given the well‐established profibrotic function of PAI‐1, we considered whether PAI‐1 may serve as a target for antifibrotic therapy in nonalcoholic steatohepatitis (NASH). We therefore determined the effect of genetic Pai‐1 deletion and pharmacologic PAI‐1 inhibition on the development of NASH‐related fibrosis in mice. Pai‐1 knockout (Pai‐1 –/–) and wild‐type control (Pai‐1 +/+) mice were fed a high‐fat/high‐cholesterol high‐sugar (HFHS) diet or a methionine‐ and choline‐deficient (MCD) diet to induce steatohepatitis with fibrosis. PAI‐1 was pharmacologically inhibited using the small molecule inhibitor TM5441 in wild‐type C57BL/6 mice fed an HFHS or MCD diet. Either genetic deletion of Pai‐1 or pharmacologic inhibition of PAI‐1 attenuated MCD diet‐induced hepatic steatosis but did not prevent hepatic inflammation or fibrosis. Targeted inhibition of PAI‐1 conferred transient protection from HFHS diet‐induced obesity and hepatic steatosis, an effect that was lost with prolonged exposure to the obesigenic diet. Neither genetic deletion of Pai‐1 nor pharmacologic inhibition of PAI‐1 prevented HFHS diet‐induced hepatic inflammation or fibrosis. Conclusion: Pai‐1 regulates hepatic lipid accumulation but does not promote NASH progression. The PAI‐1 inhibitor TM5441 effectively attenuates diet‐induced obesity and hepatic steatosis but does not prevent NASH‐related fibrosis in mice.

Abstract 566: Functional Analysis of Inducible Pluripotent Stem Cell-derived Vascular Endothelial Cells From Plasminogen Activator Inhibitor-1 Deficient Patients

Background: Plasminogen Activator inhibitor-1 (PAI-1) is the principle regulator of PA system and its enhanced expression levels are related to many pathological conditions including thrombosis and malignant tumors. We have identified two distinct PAI-1 deficient patients having apparent phenotypes of severe bleeding and impaired wound healing, both of which are not seen in the PAI-1 deficient mice. With employing inducible Pluripotent Stem (iPS) cells established from the patients, we investigated the intrinsic function of PAI-1 in endothelial cells. Methods: iPS cells, generated from PAI-1 deficient patients and control subject, were differentiated to endothelial cells. Endothelial cells were isolated by magnetic sorting with anti-VEGFR-2 antibody, and their functions and the related gene expressions were analyzed. Results: (1) Endothelial cells derived from PAI-1 deficient iPS cells (PAI-1 iPS-ECs) detached more easily from gelatin-coated dishes. (2) PAI-1 iPS-ECs migrated faster in migration assay. (3) Tube formation activities of PAI-1 iPS-ECs, especially vessel branching, were impaired compared with control iPS-ECs. (4) The expression of Dll4 gene, known to be mainly observed at the region of angiogenic-edge, was reduced in PAI-1 iPS-ECs. Conclusion: PAI-1 appeared to play important roles in the function of endothelial cells and to contribute to angiogenesis.

The vitronectin RGD motif regulates TGF-β-induced alveolar epithelial cell apoptosis.

Transforming growth factor-β (TGF-β) is a critical driver of acute lung injury and fibrosis. Injury leads to activation of TGF-β, which regulates changes in the cellular and matrix makeup of the lung during the repair and fibrosis phase. TGF-β can also initiate alveolar epithelial cell (AEC) apoptosis. Injury leads to destruction of the laminin-rich basement membrane, which is replaced by a provisional matrix composed of arginine-glycine-aspartate (RGD) motif-containing plasma matrix proteins, including vitronectin and fibronectin. To determine the role of specific matrix proteins on TGF-β-induced apoptosis, we studied primary AECs cultured on different matrix conditions and utilized mice with deletion of vitronectin (Vtn(-/-)) or mice in which the vitronectin RGD motif is mutated to nonintegrin-binding arginine-glycine-glutamate (RGE) (Vtn(RGE/RGE)). We found that AECs cultured on fibronectin and vitronectin or in wild-type mouse serum are resistant to TGF-β-induced apoptosis. In contrast, AECs cultured on laminin or in serum from Vtn(-/-) or Vtn(RGE/RGE) mice undergo robust TGF-β-induced apoptosis. Plasminogen activator inhibitor-1 (PAI-1) sensitizes AECs to greater apoptosis by disrupting AEC engagement to vitronectin. Inhibition of integrin-associated signaling proteins augments AEC apoptosis. Mice with transgenic deletion of PAI-1 have less apoptosis after bleomycin, but deletion of vitronectin or disruption of the vitronectin RGD motif reverses this protection, suggesting that the proapoptotic function of PAI-1 is mediated through vitronectin inhibition. Collectively, these data suggest that integrin-matrix signaling is an important regulator of TGF-β-mediated AEC apoptosis and that PAI-1 functions as a natural regulator of this interaction.

Plasminogen Activator Inhibitor-1 Controls Vascular Integrity by Regulating VE-Cadherin Trafficking.

BackgroundPlasminogen activator inhibitor-1 (PAI-1), a serine protease inhibitor, is expressed and secreted by endothelial cells. Patients with PAI-1 deficiency show a mild to moderate bleeding diathesis, which has been exclusively ascribed to the function of PAI-1 in down-regulating fibrinolysis. We tested the hypothesis that PAI-1 function plays a direct role in controlling vascular integrity and permeability by keeping endothelial cell-cell junctions intact.Methodology/Principal FindingsWe utilized PAI-039, a specific small molecule inhibitor of PAI-1, to investigate the role of PAI-1 in protecting endothelial integrity. In vivo inhibition of PAI-1 resulted in vascular leakage from intersegmental vessels and in the hindbrain of zebrafish embryos. In addition PAI-1 inhibition in human umbilical vein endothelial cell (HUVEC) monolayers leads to a marked decrease of transendothelial resistance and disrupted endothelial junctions. The total level of the endothelial junction regulator VE-cadherin was reduced, whereas surface VE-cadherin expression was unaltered. Moreover, PAI-1 inhibition reduced the shedding of VE-cadherin. Finally, we detected an accumulation of VE-cadherin at the Golgi apparatus.Conclusions/SignificanceOur findings indicate that PAI-1 function is important for the maintenance of endothelial monolayer and vascular integrity by controlling VE-cadherin trafficking to and from the plasma membrane. Our data further suggest that therapies using PAI-1 antagonists like PAI-039 ought to be used with caution to avoid disruption of the vessel wall.

Plasminogen Activator Inhibitor-1 in Cancer: Rationale and Insight for Future Therapeutic Testing.

Despite its function as an inhibitor of urokinase and tissue-type plasminogen activator (PA), PA inhibitor-1 (PAI-1) has a paradoxical protumorigenic role in cancer, promoting angiogenesis and tumor cell survival. In this review, we summarize preclinical evidence in support of the protumorigenic function of PAI-1 that has led to the testing of small-molecule PAI-1 inhibitors, initially developed as antithrombotic agents, in animal models of cancer. The review discusses the challenges and the opportunities that lay ahead to the development of efficacious and nontoxic PAI-1 inhibitors as anticancer agents.

Abrogation of plasminogen activator inhibitor-1-vitronectin interaction ameliorates acute kidney injury in murine endotoxemia.

Sepsis-induced acute kidney injury (AKI) contributes to the high mortality and morbidity in patients. Although the pathogenesis of AKI during sepsis is poorly understood, it is well accepted that plasminogen activator inhibitor-1 (PAI-1) and vitronectin (Vn) are involved in AKI. However, the functional cooperation between PAI-1 and Vn in septic AKI has not been completely elucidated. To address this issue, mice were utilized lacking either PAI-1 (PAI-1−/−) or expressing a PAI-1-mutant (PAI-1R101A/Q123K) in which the interaction between PAI-1 and Vn is abrogated, while other functions of PAI-1 are retained. It was found that both PAI-1−/− and PAI-1R101A/Q123K mice are associated with decreased renal dysfunction, apoptosis, inflammation, and ERK activation as compared to wild-type (WT) mice after LPS challenge. Also, PAI-1−/− mice showed attenuated fibrin deposition in the kidneys. Furthermore, a lack of PAI-1 or PAI-1-Vn interaction was found to be associated with an increase in activated Protein C (aPC) in plasma. These results demonstrate that PAI-1, through its interaction with Vn, exerts multiple deleterious mechanisms to induce AKI. Therefore, targeting of the PAI-1-Vn interaction in kidney represents an appealing therapeutic strategy for the treatment of septic AKI by not only altering the fibrinolytic capacity but also regulating PC activity.

Vitronectin-binding PAI-1 protects against the development of cardiac fibrosis through interaction with fibroblasts

Plasminogen activator inhibitor-1 (PAI-1) promotes or abates fibrotic processes occurring in different organs. Binding of PAI-1 to vitronectin, an extracellular matrix component, may inhibit vitronectin–integrin complex-mediated cellular responses in pathophysiological conditions. To investigate the importance of plasmin suppression vs vitronectin-binding pathways of PAI-1 in cardiac fibrosis, we studied uninephrectomized mice fed a high salt diet and infused with angiotensin II (Ang II) together with different PAI-1 variants, including PAI-1AK (AK) that inhibits plasminogen activators but does not bind vitronectin, PAI-1RR (RR) that binds vitronectin but does not have protease inhibitory effects or control PAI-1 (CPAI), the control mutant that has similar molecular backbone and half-life as AK and RR while retaining all functions of native PAI-1. Compared with RR and CPAI, non-vitronectin-binding AK significantly increased expression of cardiac fibroblast marker, periostin (Ang+AK 8.40±3.55 vs Ang+RR 2.23±0.44 and Ang+CPAI 2.33±0.12% positive area, both P<0.05) and cardiac fibrosis (Ang+AK 1.79±0.26% vs Ang+RR 0.91±0.18% and Ang+CPAI 0.81±0.12% fibrotic area, both P<0.05), as well as Col1 mRNA (Ang+AK 12.81±1.84 vs Ang+RR 4.04±1.06 and Ang+CPAI 5.23±1.21 fold increase, both P<0.05). To elucidate mechanisms underlying the protective effects of vitronectin-binding PAI-1 against fibrosis, fibroblasts from normal adult human ventricles were stimulated with Ang and different PAI-1 variants. Protease inhibitory AK and CPAI increased supernatant fibronectin, while decreasing plasminogen activator/plasmin activities and matrix metalloproteinase. RR and CPAI variants significantly reduced fibroblast expression of integrin β3, vitronectin level in the supernatant and fibroblast adhesion to vitronectin compared with the non-vitronectin-binding AK. Further, RR and CPAI preserved apoptotic, decreased anti-apoptotic and proliferative activities in fibroblasts. Thus, PAI-1 promotes or protects against development of cardiac fibrosis differentially through the protease inhibitory pathway or through its binding to vitronectin.

PAI-1 Leads to G1-Phase Cell-Cycle Progression through Cyclin D3/cdk4/6 Upregulation

The canonical function of plasminogen activator inhibitor-1 (PAI-1/SERPINE1) is as an inhibitor of urokinase-type plasminogen activator for blood clot maintenance, but it is now also considered a pleiotropic factor that can exert diverse cellular and tumorigenic effects. However, the mechanism controlling its pleiotropic effects is far from being understood. To elucidate the tumorigenic role of PAI-1, we tested the effects of PAI-1 after manipulation of its expression or through the use of a small-molecule inhibitor, tiplaxtinin. Downregulation of PAI-1 significantly reduced cellular proliferation through an inability to progress from the G(0-G1) phase of the cell cycle. Accordingly, overexpression of PAI-1 augmented proliferation by encouraging S-phase entry. Biochemically, cell-cycle arrest was associated with the depletion of the G(1)-phase transition complexes, cyclin D3/cdk4/6 and cyclin E/cdk2, in parallel with the upregulation of the cell-cycle inhibitors p53, p21Cip1/Waf1, and p27Kip1. PAI-1 depletion significantly decreased the tumor size of urothelial T24 and UM-UC-14 xenografts, and overexpression of PAI-1 substantially increased the tumor size of HeLa xenografts. Finally, immunohistochemical analysis of human bladder and cervical tumor tissue microarrays revealed increased expression of PAI-1 in cancerous tissue, specifically in aggressive tumors, supporting the relevance of this molecule in human tumor biology. Targeting PAI-1 has beneficial antitumoral effects and should be further investigated clinically.

PAI‐1 promotes the accumulation of exudate macrophages and worsens pulmonary fibrosis following type II alveolar epithelial cell injury

Fibrotic disorders of the lung are associated with perturbations in the plasminogen activation system. Specifically, plasminogen activator inhibitor-1 (PAI-1) expression is increased relative to the plasminogen activators. A direct role for this imbalance in modulating the severity of lung scarring following injury has been substantiated in the bleomycin model of pulmonary fibrosis. However, it remains unclear whether derangements in the plasminogen activation system contribute more generally to the pathogenesis of lung fibrosis beyond bleomycin injury. To answer this question, we employed an alternative model of lung scarring, in which type II alveolar epithelial cells (AECs) are specifically injured by administering diphtheria toxin (DT) to mice genetically engineered to express the human DT receptor (DTR) off the surfactant protein C promoter. This targeted AEC injury results in the diffuse accumulation of interstitial collagen. In the present study, we found that this targeted type II cell insult also increases PAI-1 expression in the alveolar compartment. We identified AECs and lung macrophages to be sources of PAI-1 production. To determine whether this elevated PAI-1 concentration was directly related to the severity of fibrosis, DTR(+) mice were crossed into a PAI-1-deficient background (DTR(+) : PAI-1(-/-) ). DT administration to DTR(+) : PAI-1(-/-) animals caused significantly less fibrosis than was measured in DTR(+) mice with intact PAI-1 production. PAI-1 deficiency also abrogated the accumulation of CD11b(+) exudate macrophages that were found to express PAI-1 and type-1 collagen. These observations substantiate the critical function of PAI-1 in pulmonary fibrosis pathogenesis and provide new insight into a potential mechanism by which this pro-fibrotic molecule influences collagen accumulation. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Effects of Altered Plasminogen Activator Inhibitor-1 Expression on Cardiovascular Disease

Plasminogen Activator Inhibitor-1 (PAI-1) is a multifunctional protein with the ability to not only regulate fibrinolysis through inhibition of plasminogen activation, but also cell signaling events which have direct downstream effects on cell function. Elevated plasma levels of this protein have been shown to have profound effects on the development and progression of cardiovascular diseases. However, results from a number of studies, especially those using PAI-1 deficient mouse models, have demonstrated that its function is ambiguous, with evidence of both preventing and enhancing various disease states. A number of lifestyle changes and pharmacological reagents have been identified that can regulate PAI-1 levels or function. Those reagents that target function are focused on its ability to regulate plasmin formation, and have been studied in in vivo models of thrombosis. Further investigations involving regulation of cell function could potentially resolve paradoxical issues associated with the function of this protein in regulating cardiovascular disease.

The effect of plasminogen activator inhibitor-1 on embryonic lung fibroblasts from rats

To explore the effect of plasminogen activator inhibitor-1 (PAI-1) on the proliferation and conversion of rat embryonic lung fibroblasts and the synthesis of collagen, and therefore to explore the function of PAI-1 in pulmonary fibrosis. The embryonic lung fibroblasts from pregnant Wistar rats were isolated and cultured in vitro. The reproduction rate of fibroblasts at 12 h, 24 h, and 48 h after being stimulated by PAI-1 with different concentrations (5, 10, 20, 40, 80, and 100 µg/L) was measured by MTT assay. After being stimulated by PAI-1 with the most suitable concentration (20 µg/L) for 48 h and 72 h, the expression of proliferating cell nuclear antigen (PCNA) was measured by immunocytochemical technique, and the mRNA expression of α-SMA and type-1 collagen at 24 h and 48 h was measured by real-time PCR. PAI-1 with different concentrations stimulated the proliferation of fibroblasts. The highest proliferation rate and absorbance in concentration of 20 µg/L and at 12 h were 62.6% and 0.573 ± 0.039. The comparison of different concentrations showed that the difference was significant (F = 111.112, P = 0.000). Therefore, 20 µg/L was selected as the most suitable concentration. Using immunocytochemical method, the optical density of PCNA at 48 h and 72 h were 3685 ± 686 and 2530 ± 477 after being stimulated with 20 µg/L PAI-1. The comparison showed significant difference (F = 7.85, P = 0.02). The expression of α-SMA increased (230 ± 11)% and (159 ± 9)% at 24 h and 48 h after being stimulated with 20 µg/L PAI-1, and the difference was significant (F = 39.92, P = 0.0003). The expression of type-1 collagen increased (92 ± 8)% and (65 ± 12)%, the difference being significant (F = 32.61, P = 0.0006). PAI-1 can promote the proliferation and conversion of fibroblasts and the synthesis of collagen, which may be involved in the pathogenesis of pulmonary interstitial fibrosis.

Life‐threatening hemorrhage and prolonged wound healing are remarkable phenotypes manifested by complete plasminogen activator inhibitor‐1 deficiency in humans

Plasminogen activator inhibitor-1 (PAI-1) is the primary physiological regulator of urokinase plasminogen activator (uPA) and tissue plasminogen activator (tPA) activity. A number of studies have shown that elevated levels of PAI-1 are related to pathological states such as an increased risk of arterial thrombotic events and a poor prognosis for cancer patients; however, there are few reports about PAI-1 deficiency in humans because the disorder is very rare. To understand the in vivo impact of a complete PAI-1 deficiency, Serpine1(-/-) mice were generated; a number of in vivo studies have been conducted to elucidate the function of PAI-1 using Serpine1(-/-) mice. The phenotypes demonstrated in Serpine1(-/-) mice, however, were quite different from those in humans. Therefore, it is necessary to find out and analyze SERPINE1 deficiency in humans. The patient is a 47-year-old woman who has had multiple episodes of major bleeding. Although most of the patient's blood coagulation factors were functionally normal, her PAI-1 antigen levels were undetectable. Therefore, DNA sequencing of the SERPINE1 gene were analyzed. The proband had a homozygous 1-bp duplication (C) at exon 3 (c.356dupC; p.Ile120AspfsX42). Both wild-type PAI-1 (42.7 kDa) and mutated (Mut) PAI-1 (14.7kDa) were expressed in COS-1 cells, although the level of Mut PAI-1 expressed in the cell lysates was much lower. Wild-type PAI-1 was observed in the culture supernatant, whereas no Mut PAI-1 was detected in the supernatant. Considering the results of the present study, the translation of mouse studies to humans must be performed with great care.

Association of elevated plasminogen activator inhibitor 1 levels with diminished lung function in patients with asthma

We previously reported that plasminogen activator inhibitor 1 (PAI-1) was upregulated in human asthmatic airways and promotes airway fibrosis in an allergen-challenged murine model of asthma.To examine whether elevated plasma levels of PAI-1 are associated with poor lung function in asthmatic patients.Five hundred nineteen adults were eligible for the study, and ultimately 353 adults were enrolled and completed the baseline protocol between January 24, 2004, and July 30, 2005. Of these, 231 adults with asthma from the Chicago Initiative to Raise Asthma Health Equity study were randomly selected and the plasma levels of PAI-1 were measured by enzyme-linked immunosorbent assay. Asthma burden, medication, smoking status, and body mass index (BMI) were obtained by history and spirometry was performed. A multivariate regression analysis was performed to evaluate the association of PAI-1 levels and lung function and the potential determinant variables that were associated with PAI-1.We found associations between PAI-1 and BMI (β = 0.606, P = .002), smoking (β = 7.526, P = .001), and African American race (β = -9.061, P = .01). Obese patients showed a significant increase in PAI-1, and current smokers demonstrated higher levels of PAI-1 compared with nonsmokers. When we evaluated the associations between lung function parameters and PAI-1, we found that PAI-1 was negatively associated with forced vital capacity (FVC) (β = -0.098, P = .011) but not with forced expiratory volume in 1 second (FEV(1)) or the FEV(1)/FVC ratio. There was a negative association between BMI and FVC, and PAI-1 may mediate some of this association.This study suggests a significant association between PAI-1 and lung function in patients with asthma. The effect of obesity on FVC may in part be mediated by PAI-1.