Plasminogen Activator Inhibitor-1 Activity Research Articles

Plasminogen Degradation by Neutrophil Elastase in Pleural Infection, Not High Plasminogen Activator Inhibitor-1 (PAI-1), is the Cause of Intrapleural Lytic Failure.

Complex pleural space infections often require treatment with multiple doses of intrapleural tissue-plasminogen activator(tPA) and deoxyribonuclease(DNase), with treatment failure frequently necessitating surgery. Pleural infections are rich in neutrophils, and neutrophil elastase degrades plasminogen, the target substrate of tPA, that is required to generate fibrinolysis. We hypothesized that pleural fluid from patients with pleural space infection would have high elastase activity, evidence of inflammatory plasminogen degradation, and low fibrinolytic potential in response to tPA that could be rescued with plasminogen supplementation. Does neutrophil elastase degradation of plasminogen contribute to intrapleural fibrinolytic failure? We obtained infected pleural fluid and circulating plasma from hospitalized adults(n=10) with IRB approval from a randomized trial evaluating intrapleural fibrinolytics versus surgery for initial management of pleural space infections. Samples were collected pre-intervention, post-intervention day-1(PID1), PID2, and PID3. Activity assays, enzyme-linked immunosorbent assays, and western blot(WB) analysis were performed, and turbidometric measurements of fibrinolysis were performed on pleural fluid +/- exogenous plasminogen supplementation. Results are reported as median(Q1, Q3) or n(%) as appropriate, with alpha set at 0.05. Pleural fluid elastase activity was >4-fold higher(p=0.02) and plasminogen antigen levels >3-fold lower(p=0.04) than their corresponding plasma. Pleural fluid WB analysis demonstrated abundant plasminogen degradation fragments consistent with elastase degradation patterns. We found that plasminogen-activator inhibitor-1(PAI-1), the native tPA inhibitor, had high antigen levels pre-intervention but the overwhelming majority of this PAI-1(82%) was not active(p=0.003), and all PAI-1 activity was lost by PID2 in patients receiving intrapleural tPA/DNase. Finally, using turbidity clot lysis assays we found that 9 of 10 patients' pleural fluid was unable to generate a significant fibrinolytic response when challenged with tPA and that plasminogen supplementation rescued fibrinolysis in all patients. Inflammatory plasminogen deficiency, not high PAI-1 activity, is a significant contributor to intrapleural fibrinolytic failure.

Platelet activity, coagulation, and fibrinolysis in long-term users of anabolic-androgenic steroids compared to strength-trained athletes

IntroductionUse of anabolic-androgenic steroids (AAS) is associated with adverse cardiovascular (CV) effects, including potential prothrombotic effects. This study aimed to assess platelet activation and aggregation, coagulation, and fibrinolysis, in long-term AAS users compared to non-using strength-trained athletes. Materials and methodsThirty-seven strength-trained men using AAS were compared to seventeen non-using professional strength-trained athletes at similar age (median 33 years). AAS use was verified by blood and urine analyses. Platelet Function Analyzer 100 (PFA-100) and whole blood impedance aggregometry with thrombin, arachidonic acid, and ADP as agonists, were performed to evaluate platelet aggregation. ELISA methods were used for markers of platelet activation. Fibrinogen, D-dimer, the coagulation inhibitors protein S and C activity, and antithrombin were measured by routine. Fibrinolysis was evaluated by Plasminogen Activator Inhibitor-1 (PAI-1) activity. ResultsThere were no significant differences in platelet aggregation between the two groups. Von Willebrand factor was lower among the AAS users (p < 0.01), and P-Selectin was slightly higher (p = 0.05), whereas CD40 Ligand, β-thromboglobulin, and thrombospondin did not differ significantly. No differences were found in the assessed coagulation inhibitors. Higher D-dimer levels (p < 0.01) and lower PAI-1 activity (p < 0.01) were found among the AAS users. ConclusionsThe investigated long-term users of AAS did not exhibit elevated platelet activity compared to strength-trained non-using athletes. However, AAS use was associated with higher D-dimer levels and lower PAI-1 activity. These findings suggest that any prothrombotic effect of long-term AAS use may predominantly involve other aspects of the hemostatic system than blood platelets.

Effects of Anti-Fibrotic Drugs on Transcriptome of Peripheral Blood Mononuclear Cells in Idiopathic Pulmonary Fibrosis.

Two anti-fibrotic drugs, pirfenidone (PFD) and nintedanib (NTD), are currently used to treat idiopathic pulmonary fibrosis (IPF). Peripheral blood mononuclear cells (PBMCs) are immunocompetent cells that could orchestrate cell-cell interactions associated with IPF pathogenesis. We employed RNA sequencing to examine the transcriptome signature in the bulk PBMCs of patients with IPF and the effects of anti-fibrotic drugs on these signatures. Differentially expressed genes (DEGs) between "patients with IPF and healthy controls" and "before and after anti-fibrotic treatment" were analyzed. Enrichment analysis suggested that fatty acid elongation interferes with TGF-β/Smad signaling and the production of oxidative stress since treatment with NTD upregulates the fatty acid elongation enzymes ELOVL6. Treatment with PFD downregulates COL1A1, which produces wound-healing collagens because activated monocyte-derived macrophages participate in the production of collagen, type I, and alpha 1 during tissue damage. Plasminogen activator inhibitor-1 (PAI-1) regulates wound healing by inhibiting plasmin-mediated matrix metalloproteinase activation, and the inhibition of PAI-1 activity attenuates lung fibrosis. DEG analysis suggested that both the PFD and NTD upregulate SERPINE1, which regulates PAI-1 activity. This study embraces a novel approach by using RNA sequencing to examine PBMCs in IPF, potentially revealing systemic biomarkers or pathways that could be targeted for therapy.

Exercise testing unmasks exaggerated blood pressure independent of fibrinolytic response in Black but not White postmenopausal females.

Exercise testing unmasks more exaggerated systolic blood pressure responses (SBP) in Black compared with White male adults. Such responses, if translatable to females, may detect racial disparities particularly relevant during menopause. Given the endothelial involvement in BP regulation and as a source of fibrinolytic markers, it follows that fibrinolytic and BP response to exercise could be linked. Thus, we examined BP and fibrinolytic responses to exercise testing in Black and White postmenopausal females. Postmenopausal females (Black = 40; White = 41; 51-70 yr) performed maximal treadmill exercise. BP and blood draws were conducted before and immediately after exercise. Plasma samples, using minimal stasis, were analyzed for tissue plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI-1) activity and antigen, respectively. Resting SBP and fibrinolytic potential were similar between races. Black females exhibited greater increases in SBP during exercise [change (d)=75, 95% CI: 64-86 mmHg, P < 0.001] than White females (d = 60, 95% CI: 48-71 mmHg, P < 0.001). Black compared with White females had smaller changes in tPA (d = 3.27, 95% CI: 2.28-4.27 IU/mL, P < 0.001 vs. d = 5.55, 95% CI: 4.58-6.53, P < 0.001) and PAI-1 (d = -2.89, 95% CI: -4.39 to -1.40 IU/mL, P < 0.001 vs. d = -5.08, 95% CI: -6.59 to -3.61, P < 0.001) activities after exercise. SBP exercise-induced changes were not associated with tPA (r = -0.10, P = 0.42) or PAI-1 (r = 0.13, P = 0.30), without any influence of race (P > 0.05). Our findings show that maximal exercise unmasks risk factors for cardiovascular disease in Black postmenopausal females.NEW & NOTEWORTHY Exaggerated SBP responses to exercise testing are more frequent in Black than in White male adults. Such responses, if translatable to females, may detect early racial disparities arriving during menopause. Because the endothelium regulates BP and fibrinolytic responses, these could be linked during exercise. At peak exercise, Black but not White postmenopausal females had more exaggerated SPB responses regardless of reduced fibrinolytic potential. Maximal exercise unmasked risk factors for cardiovascular disease in Black postmenopausal females.

Urokinase-type plasminogen activator and plasminogen activator inhibitor-1 complex as a serum biomarker for COVID-19.

Patients with coronavirus disease-2019 (COVID-19) have an increased risk of thrombosis and acute respiratory distress syndrome (ARDS). Thrombosis is often attributed to increases in plasminogen activator inhibitor-1 (PAI-1) and a shut-down of fibrinolysis (blood clot dissolution). Decreased urokinase-type plasminogen activator (uPA), a protease necessary for cell-associated plasmin generation, and increased tissue-type plasminogen activator (tPA) and PAI-1 levels have been reported in COVID-19 patients. Because these factors can occur in free and complexed forms with differences in their biological functions, we examined the predictive impact of uPA, tPA, and PAI-1 in their free forms and complexes as a biomarker for COVID-19 severity and the development of ARDS. In this retrospective study of 69 Japanese adults hospitalized with COVID-19 and 20 healthy donors, we found elevated free, non-complexed PAI-1 antigen, low circulating uPA, and uPA/PAI-1 but not tPA/PAI-1 complex levels to be associated with COVID-19 severity and ARDS development. This biomarker profile was typical for patients in the complicated phase. Lack of PAI-1 activity in circulation despite free, non-complexed PAI-1 protein and plasmin/α2anti-plasmin complex correlated with suPAR and sVCAM levels, markers indicating endothelial dysfunction. Furthermore, uPA/PAI-1 complex levels positively correlated with TNFα, a cytokine reported to trigger inflammatory cell death and tissue damage. Those levels also positively correlated with lymphopenia and the pro-inflammatory factors interleukin1β (IL1β), IL6, and C-reactive protein, markers associated with the anti-viral inflammatory response. These findings argue for using uPA and uPA/PAI-1 as novel biomarkers to detect patients at risk of developing severe COVID-19, including ARDS.

Fibrinolysis Assessment with Tpa-ROTEM in Patients with Bleeding Disorders of Unknown Cause (BDUC)

Background: In 40-70% of patients referred to the hematologist for evaluation of bleeding symptoms, no cause for their increased bleeding tendency can be found using currently available hemostasis laboratory tests. This group is classified as patients with bleeding disorder of unknown cause (BDUC). The lack of clear guidelines concerning diagnosis, management and genetic counseling in BDUC-patients poses a challenge for patients, family members and treating physicians. Several hemostasis assays have been investigated in BDUC-patients, but little is known about the role of the fibrinolytic pathway in this patient group. This can be explained by the lack of standardized fibrinolysis tests and the limited availability of these tests in laboratories. To further unravel potential bleeding mechanisms in BDUC, in the present study we assessed fibrinolysis in BDUC patients by using a global whole blood tPA ROTEM assay and determining of individual fibrinolysis proteins. Aim: To investigate the capacity of the tPA-ROTEM assay to detect fibrinolytic abnormalities in BDUC-patients and to correlate these findings with fibrinolytic protein activity levels in plasma. Methods: Data from patients referred to the hematologist for bleeding evaluation and included in the Prediction of Evaluation in Adult Hematologic Patients with Bleeding Tendencies (ProBe-AHP) study (METC:14-4-036) were used. BDUC-patients were identified based on (1) a clinically relevant increased bleeding tendency and (2) no abnormalities in extended hemostasis laboratory testing. tPA-ROTEM assay was done according to the in 2016 validated and published method on the ROTEM device. Fibrinolysis protein plasma levels, including plasminogen, plasminogen activator inhibitor 1 (PAI-1) antigen and activity, tissue plasminogen activator (tPA) antigen, alpha2-antiplasmin and thrombin activatable fibrinolysis inhibitor (TAFI), were measured using ELISA assays. Pre-specified definitions of hyper- and hypofibrinolysis as measured by tPA-ROTEM were applied to identify hyper- and hypofibrinolytic profiles. Results: tPA-ROTEM identified a hyperfibrinolytic profile in 15/73 (20%) of BDUC-patients, a hypofibrinolytic profile in 16/73 (22%) of BDUC-patients and a normal profile in 42 BDUC-patients (58%). Plasminogen activity inhibitor 1 (PAI-1) activity and antigen levels and α2-antiplasmin levels were lower in BDUC-patients with a hyperfibrinolytic profile compared to BDUC-patients with a hypofibrinolytic profile. No statistically significant correlations between tPA-ROTEM parameters and fibrinolysis protein plasma levels were identified using multivariate regression analysis. Conclusion: tPA-ROTEM identified a hyperfibrinolytic profile in 20% of BDUC-patients. In this group, the lower PAI-1 activity and antigen levels and lower α2-antiplasmin levels are in concordance with the expected changes in case of hyperfibrinolysis. These findings indicate that these fibrinolysis protein plasma levels are within the lower functional range of their distribution, shifting the balance towards increased clot lysis leading to an increased bleeding tendency. These findings might deliver evidence to the use of antifibrinolytic therapies in BDUC-patients in case of bleeding or interventions. Informed consent and approval from the medical-ethical committee from Maastricht (METC azM/UM) were obtained.

Development of a Hypercoagulable-Hypofibrinolytic State Early After Spinal Cord Injury

ObjectivesTo determine whether spinal cord injury (SCI) is associated with adverse changes in coagulation and fibrinolytic factors that underlie thrombogenesis and contribute to atherothrombotic events such as myocardial infarctions (MIs) and strokes. DesignCross-sectional study. SettingNeurorehabilitation hospital and general community. ParticipantsThirty young and middle-aged (20-58 years) adults (N=30) were studied: 14 non-injured community dwelling adults. (11M/4F) and 16 with subacute tetraplegic motor complete SCI during initial inpatient rehabilitation (13M/3F; time since injury: 11.8±5.3 wk). InterventionsNot applicable. Main Outcome MeasuresCirculating markers of coagulation [von Willebrand factor (vWf) and factors VII, VIII, and X], the fibrinolytic system [tissue-type plasminogen activator (t-PA), and plasminogen activator inhibitor-1 (PAI-1) antigen and activity], and fibrin formation (D-dimer) were determined by enzyme immunoassay. ResultsThirty young and middle-aged (20-58 years) adults were studied: 14 non-injured (11M/4F) and 16 with subacute tetraplegic motor complete SCI (13M/3F; time since injury: range 4-25 wk). Circulating levels of coagulation factors VII, VIII, and X were significantly higher (∼20%-45%; P<.05) in the adults with SCI than non-injured adults, whereas vWf was similar between groups. Fibrinolytic markers were adversely disrupted with SCI with t-PA antigen, PAI-1 antigen and PAI-1 activity were markedly higher (∼50%-800%; P<.05) in adults with SCI compared with non-injured adults. The molar concentration ratio of active t-PA to PAI-1 was significantly higher (∼350%) in adults with SCI. Concordant with coagulation cascade activation and fibrinolytic system inhibition, D-dimer concentrations were markedly ∼70% higher (P<.05) in adults with SCI compared with non-injured adults. ConclusionsSubacute tetraplegic motor complete SCI is associated with a prothrombotic hemostatic profile. Adverse changes in the coagulation cascade and fibrinolytic system appear to occur early after injury and may contribute to the increased atherothrombotic risk in adults living with SCI.

PAI-1 genetic polymorphisms influence septic patients' outcomes by regulating neutrophil activity.

Plasminogen activator inhibitor-1 (PAI-1) plays an important role in the pathophysiology of sepsis, but the exact mechanism remains debatable. In this study, we investigated the associations among the serum levels of PAI-1, the incidence of 4G/5G promoter PAI-1 gene polymorphisms, immunological indicators, and clinical outcomes in septic patients. A total of 181 patients aged 18-80 years with sepsis between November 2016 and August 2018 in the intensive care unit in the Xinhua Hospital were recruited in this retrospective study, with 28-day mortality as the primary outcome. The initial serum level of PAI-1 and the presence of rs1799768 single nucleotide polymorphisms (SNPs) were examined. Univariate logistic regression and multivariate analyses were performed to determine the factors associated with different genotypes of PAI-1, serum level of PAI-1, and 28-day mortality. The logistic analysis suggested that a high serum level of PAI-1 was associated with the rs1799768 SNP of PAI-1 (4G/4G and 4G/5G) (Odds ratio [OR]: 2.49; 95% confidence interval [CI]: 1.09, 5.68). Furthermore, a high serum level of PAI-1 strongly influenced 28-day mortality (OR 3.36; 95% CI 1.51, 7.49). The expression and activation of neutrophils (OR 0.96; 95% CI 0.93, 0.99), as well as the changes in the expression patterns of cytokines and chemokine-associated neutrophils (OR: 1.00; 95% CI: 1.00, 1.00), were both regulated by the genotype of PAI-1. Genetic polymorphisms of PAI-1 can influence the serum levels of PAI-1, which might contribute to mortality by affecting neutrophil activity. Thus, patients with severe sepsis might clinically benefit from enhanced neutrophil clearance and the resolution of inflammation via the regulation of PAI-1 expression and activity.

PAI-1 Overexpression in Valvular Interstitial Cells Contributes to Hypofibrinolysis in Aortic Stenosis.

Aortic stenosis (AS) is associated with hypofibrinolysis, but its mechanism is poorly understood. We investigated whether LDL cholesterol affects plasminogen activator inhibitor 1 (PAI-1) expression, which may contribute to hypofibrinolysis in AS. Stenotic valves were obtained from 75 severe AS patients during valve replacement to assess lipids accumulation, together with PAI-1 and nuclear factor-κB (NF-κB) expression. Five control valves from autopsy healthy individuals served as controls. The expression of PAI-1 in valve interstitial cells (VICs) after LDL stimulation was assessed at protein and mRNA levels. PAI-1 activity inhibitor (TM5275) and NF-κB inhibitor (BAY 11-7082) were used to suppress PAI-1 activity or NF-κB pathway. Clot lysis time (CLT) was performed to assess fibrinolytic capacity in VICs cultures. Solely AS valves showed PAI-1 expression, the amount of which was correlated with lipid accumulation and AS severity and co-expressed with NF-κB. In vitro VICs showed abundant PAI-1 expression. LDL stimulation increased PAI-1 levels in VICs supernatants and prolonged CLT. PAI-1 activity inhibition shortened CLT, while NF-κB inhibition decreased PAI-1 and SERPINE1 expression in VICs, its level in supernatants and shortened CLT. In severe AS, valvular PAI-1 overexpression driven by lipids accumulation contributes to hypofibrinolysis and AS severity.

Obesity paradox in acute myocardial infarction: Is plasminogen activator inhibitor 1 the culprit?

The obesity paradox continues to puzzle scientists. The unexpected observation of a higher incidence but more favorable outcomes in obese patients has been described in several cardiovascular and non-cardiovascular conditions. A number of possible causes of the paradox have been proposed. Plasminogen activator inhibitor 1 (PAI-1) has not yet been evaluated in this context. Our study group investigated the prognostic value of PAI-1 dynamics in the early stages of acute ST elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention. A higher rise in PAI-1 activity within 24 h of STEMI was associated with worse long-term outcomes. Within the study population, which involved 87 consecutive patients, we observed a certain pattern of PAI-1 dynamics that may be protective in obese patients. In these patients, initial PAI-1 activity levels were elevated, a fact in line with the higher incidence of acute coronary syndromes in the obese population. However, the increase in PAI-1 activity during first 24 h of STEMI was not as pronounced in obese patients. It is our hypothesis that this correlation may prove protective in this population. If confirmed in larger studies, this observation may provide a piece of the puzzle towards elucidating the origins of the obesity paradox, as well as further promote the development of PAI-1 inhibitors as a viable therapeutic option for STEMI patients.

Minoxidil Regulates Aging-Like Phenotypes in Rat Cortical Astrocytes In Vitro.

Mainly due to the slanted focus on the mechanism and regulation of neuronal aging, research on astrocyte aging and its modulation during brain aging is scarce. In this study, we established aged astrocyte culture model by long-term culturing. Cellular senescence was confirmed through SA-β-gal staining as well as through the examination of morphological, molecular, and functional markers. RNA sequencing and functional analysis of astrocytes were performed to further investigate the detailed characteristics of the aged astrocyte model. Along with aged phenotypes, decreased astrocytic proliferation, migration, mitochondrial energetic function and support for neuronal survival and differentiation has been observed in aged astrocytes. In addition, increased expression of cytokines and chemokine-related factors including plasminogen activator inhibitor -1 (PAI-1) was observed in aged astrocytes. Using the RNA sequencing results, we searched potential drugs that can normalize the dysregulated gene expression pattern observed in long-term cultured aged astrocytes. Among several candidates, minoxidil, a pyrimidine-derived anti-hypertensive and anti-pattern hair loss drug, normalized the increased number of SA-β-gal positive cells and nuclear size in aged astrocytes. In addition, minoxidil restored up-regulated activity of PAI-1 and increased mitochondrial superoxide production in aged astrocytes. We concluded that long term culture of astrocytes can be used as a reliable model for the study of astrocyte senescence and minoxidil can be a plausible candidate for the regulation of brain aging.

Association of the metabolic syndrome with PAI 1act and clot lysis time over a 10-year follow up in an African population

Background and aimsThe association between the metabolic syndrome (MetS) and plasminogen activator inhibitor-1 (PAI-1) has been well established in cross-sectional studies. It is less clear whether this translates into decreased clot lysis rates and very little information is available on non-European populations. Little is known regarding prospective associations and whether clot lysis progressively worsens in MetS individuals over time. We determined the prospective association of MetS with PAI-1 activity (PAI-1act) and clot lysis time (CLT) over a 10-year period. Methods and resultsAs many as 2010 African men and women aged ≥30 years were stratified according to MetS status and number of MetS criteria (0–5). We also determined the contribution of the PAI-1 4G/5G polymorphism to these associations and identified which MetS criteria had the strongest associations with PAI-1act and CLT. Both PAI-1act and CLT remained consistently elevated in individuals with MetS throughout the 10-year period. PAI-1act and CLT did not increase more over time in MetS individuals than in controls. The 4G/5G genotype did not influence the association of PAI-1act or clot lysis with MetS. Increased waist circumference, increased triglycerides and decreased HDL-C were the main predictors of PAI-1act and CLT. ConclusionsBlack South Africans with MetS had increased PAI-1act and longer CLTs than individuals without MetS. The inhibited clot lysis in MetS did, however, not deteriorate over time compared to controls. Of the MetS criteria, obesity and altered lipids were the main predictors of PAI-1act and CLT and are thus potential targets for prevention strategies to decrease thrombotic risk.

Effects of the New Thrombolytic Compound LT3001 on Acute Brain Tissue Damage After Focal Embolic Stroke in Rats.

LT3001 is a novel synthetic small molecule with thrombolytic and free radical scavenging activities. In this study, we tested the effects of LT3001 as a potential alternative thrombolytic in focal embolic ischemic stroke rat model. Stroked rats received intravenous injection of 10mg/kg LT3001 or tPA at 1.5, 3, or 4.5h after stroke, respectively, and the outcomes were measured at different time points after stroke by performing multi-parametric MRI, 2,3,5-triphenyltetrazolium chloride (TTC) staining, and modified neurological severity score. Lastly, we assessed the effect of LT3001 on the tPA activity in vitro, the international normalized ratio (INR), and the serum levels of active tPA and plasminogen activator inhibitor-1 (PAI-1). LT3001 treated at 1.5h after stroke is neuroprotective by reducing the CBF lesion size and lowering diffusion and T2 lesion size measured by MRI, which is consistent with the reduction in TTC-stained infarction. When treated at 3h after stroke, LT3001 had significantly better therapeutic effects regarding reduction of infarct size, swelling rate, and hemorrhagic transformation compared to tPA. When treated at 4.5h after stroke, tPA, but not LT3001, significantly increased brain swelling and intracerebral hemorrhagic transformation. Lastly, LT3001 did not interfere with tPA activity in vitro, or significantly alter the INR and serum levels of active tPA and PAI-1 in vivo. Our data suggests that LT3001 is neuroprotective in focal embolic stroke rat model. It might have thrombolytic property, not interfere with tPA/PAI-1 activity, and cause less risk of hemorrhagic transformation compared to the conventional tPA. Taken together, LT3001 might be developed as a novel therapy for treating thrombotic ischemic stroke.

PSUN171 CORRELATIONS BETWEEN SERUM AND TEAR PLASMINOGEN ACTIVATOR INHIBITOR-1 (PAI-1) AND TISSUE PLASMINOGEN ACTIVATOR (tPA) IN PATIENTS WITH DIABETIC RETINOPATHY

Abstract Introduction Diabetic retinopathy (DR) is a leading cause of blindness and visual disability, worldwide. The aim of the study was to investigate the correlation between tears and plasma levels of activity of tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) in patients with diabetic retinopathy. Method Patients with T2DM and DR (n=26) were enrolled in this study. Blood and tears samples were obtained from both groups and analysed for PAI-1 and tPA activities. Anthropometric measurements were also obtained. Results There was no correlation between serum and tear PAI-1 levels with a Spearman's coefficient of 0.028 (p=0.928). We were also unable to detect significant correlations between serum and tear tPA levels. However, there was a significant positive correlation between levels of tears PAI-1 and BMI (r=0.555, p=0.026). Conclusion This present study demonstrated no significant correlations between tears and serum PAI-1 and tPA, which was most likely due to the small sample size. However, the significant correlation between tear PAI-1 levels with BMI could indicate the potential role of tear biomarkers in diabetic retinopathy in obese patients. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

The role of the platelet pool of Plasminogen Activator Inhibitor-1 in well-controlled type 2 diabetes patients.

BackgroundThe main inhibitor of the fibrinolytic system, Plasminogen Activator Inhibitor -1 (PAI-1), irreversibly binds tissue-type Plasminogen Activator (t-PA) and thereby inhibits the protective action of tPA against thrombus formation. Elevated levels of plasma PAI-1 are associated with an increased risk of cardiovascular events and are observed in subjects with type 2 diabetes (T2D) and obesity. Platelets contain the majority of PAI-1 present in blood and exhibit the ability to synthesis active PAI-1. Diabetic platelets are known to be hyper-reactive and larger in size; however, whether these features affect their contribution to the elevated levels of plasma PAI-1 in T2D is not established.ObjectivesTo characterize the PAI-1 antigen content and the mRNA expression in platelets from T2D subjects compared to obese and lean control subjects, in order to elucidate the role of platelet PAI-1 in T2D.MethodsNine subjects with T2D and obesity were recruited from Primary Care Centers together with 15 healthy control subjects (8 lean subjects and 7 with obesity). PAI-1 antigen levels in plasma, serum and platelets were determined by ELISA, and PAI-1 mRNA expression was analyzed by qPCR.ResultsThere was no significant difference in PAI-1 mRNA expression or PAI-1 antigen in platelets in T2D subject in comparison to obese and lean control subjects. An elevated level of plasma PAI-1 was seen in both T2D and obese subjects. PAI-1 gene expression was significantly higher in both obese groups compared to lean.ConclusionSimilar levels of protein and mRNA expression of PAI-1 in platelets from T2D, obese and lean subjects indicate a limited role of platelets for the elevated plasma PAI-1 levels. However, an increased synthesis rate of mRNA transcripts in platelets from T2D and an increased release of PAI-1 could also result in similar mRNA and protein levels. Hence, synthesis and release rates of PAI-1 from platelets in T2D and obesity need to be investigated to further elucidate the role of platelets in obesity and T2D.

Family-based analysis of -675 4G/5G polymorphism in the PAI-1 gene of polycystic ovary syndrome in Chinese population

Previous studies have shown that 4G/5G polymorphism in promoter region of plasminogen activator inhibitor-1 (PAI-1) gene can affect insulin sensitivity by elevating the level and activity of plasma PAI-1. In order to elucidate the relationship between the polymorphism of PAI-1 gene and polycystic ovary syndrome (PCOS), we used transmission disequilibrium test (TDT) to study the family of PCOS. Eight hundred and fifty-five participants consisting of 285 trios (mother, father and offspring with PCOS) were recruited at the Center of Reproductive Medicine, Shandong University from July 2007 to August 2014. 4G/5G polymorphism of PAI-1 gene was genotyped using direct sequencing protocol and TDT was used to analyse the association between PAI-1 gene and PCOS. Though the 5G allele in PAI-1 gene was overtransmitted in families, no statistical significance existed and there was no association between PAI-1 gene and PCOS, indicating that PAI-1 gene was unlikely to play a major role in the aetiology of PCOS in Chinese population. Impact Statement What is already known on this subject? Some studies have shown that 4G/5G polymorphism in promoter region of plasminogen activator inhibitor-1 (PAI-1) gene can affect insulin sensitivity by elevating the level and activity of plasma PAI-1, participating in the formation of insulin resistance (IR). What do the results of this study add? Though the 5G allele in PAI-1 gene was overtransmitted in families, no statistical significance existed and there was no association between PAI-1 gene and polycystic ovary syndrome (PCOS). What are the implications of these findings for clinical practice and/or further research? PAI-1 gene was unlikely to play a major role in the aetiology of PCOS.

Compartmentalized Actions of the Plasminogen Activator Inhibitors, PAI-1 and Nsp, in Ischemic Stroke.

Tissue plasminogen activator (tPA) is a multifunctional protease. In blood tPA is best understood for its role in fibrinolysis, whereas in the brain tPA is reported to regulate blood-brain barrier (BBB) function and to promote neurodegeneration. Thrombolytic tPA is used for the treatment of ischemic stroke. However, its use is associated with an increased risk of hemorrhagic transformation. In blood the primary regulator of tPA activity is plasminogen activator inhibitor 1 (PAI-1), whereas in the brain, its primary inhibitor is thought to be neuroserpin (Nsp). In this study, we compare the effects of PAI-1 and Nsp deficiency in a mouse model of ischemic stroke and show that tPA has both beneficial and harmful effects that are differentially regulated by PAI-1 and Nsp. Following ischemic stroke Nsp deficiency in mice leads to larger strokes, increased BBB permeability, and increased spontaneous intracerebral hemorrhage. In contrast, PAI-1 deficiency results in smaller infarcts and increased cerebral blood flow recovery. Mechanistically, our data suggests that these differences are largely due to the compartmentalized action of PAI-1 and Nsp, with Nsp deficiency enhancing tPA activity in the CNS which increases BBB permeability and worsens stroke outcomes, while PAI-1 deficiency enhances fibrinolysis and improves recovery. Finally, we show that treatment with a combination therapy that enhances endogenous fibrinolysis by inhibiting PAI-1 with MDI-2268 and reduces BBB permeability by inhibiting tPA-mediated PDGFRα signaling with imatinib significantly reduces infarct size compared to vehicle-treated mice and to mice with either treatment alone.

Delayed Plasma Clot Lysis in Adult Patients with Primary Immune Thrombocytopenia (ITP)

Introduction: Primary immune thrombocytopenia (ITP) is an orphan disease characterized by very low platelet counts. Patients have heterogeneous bleeding phenotypes, which are not only determined by platelet counts, also a paradoxically increased thrombotic risk has been observed.Aim: To investigate, whether the fibrinolysis inhibitors plasminogen activator inhibitor-1 (PAI-1) and α2-antiplasmin are associated with impaired plasma clot lysis in primary ITP patients in comparison to non-immunologic thrombocytopenic controls (TPC) and healthy controls (HC). Furthermore, associations with bleeding severity and previous thrombotic events were investigated.Methods: Patients from the Vienna ITP biobank (EC 1843/2016), a multi-centric study including adult patients with primary ITP were investigated and compared to age- and sex-matched control groups: TPC with thrombocytopenia after chemotherapy and HC. Informed consent was obtained from all individuals before study inclusion. A clot formation and lysis assay (CLA) was performed according to the recommendations of the ISTH SSC. Platelet poor plasma samples were measured in duplicates for each patient and control. PAI-1 (PAI-1 Actibind ELISA, Technoclone, Vienna, Austria) and α2-antiplasmin by the chromogenic STA Stachrom antiplasmin assay (Diagnostic Stago, Asnieres, France) were measured. Bleeding severity was measured using the ITP-specific ITP-ISTH BAT (Rodeghiero et al. 2013).Results: In total, 37 primary ITP patients, 18 TPC and 156 healthy controls were analyzed (Table 1). Primary ITP patients had a higher BMI than HC. Bleeding severity was higher and more ITP patients had a thrombosis history compared to HC, whereas there was no difference in comparison to TPC. PAI-1 activity was highest in ITP patients, with a statistically significant difference in comparison to HC. α2-antiplasmin activity was higher in ITP patients than in TPC, whereas there was no difference in comparison to HC.After adjustment for sex, age, BMI and fibrinogen, primary ITP patients had a reduced clot formation rate (V max) and significantly delayed plasma clot lysis compared to TPC and HC (Table 2). Also, the lag phase and time to peak absorbance (TTP) were prolonged with a significant difference in comparison to HC.To investigate outliers of PAI-1 and α2-antiplasmin, we calculated cut-offs at the 75 th percentile of healthy controls (PAI-1: ≥ 3.1 U/mL, α2-antiplasmin: ≥ 107.0 %). 14 (37.8 %) ITP patients had PAI-1 levels and 10 (27.0 %) ITP patients had α2-antiplasmin activity above the cut-off. ITP patients with high PAI-1 levels had mildly delayed clot lysis in comparison to those below with a significantly lower maximal lysis rate (mLR). ITP patients with α2-antiplasmin activity above the cut-off had a significantly shorter lag phase, faster V max and shorter TTP than patients below the cut-off, whereas there was no difference in clot lysis. No differences between ITP patients above or below the respective cut-offs of PAI-1 and α2-antiplasmin regarding their bleeding severity and thrombosis incidence were observed (Table 3).Conclusion: Primary ITP patients have a tendency towards increased PAI-1 activity, which is associated with considerably delayed plasma clot lysis. Albeit an association with the bleeding score could not be identified, this impaired lysis could be seen as a counter-regulation and at least contribute to the relatively mild bleeding tendency in patients with ITP. [Display omitted] DisclosuresPabinger: CSL Behring: Consultancy, Honoraria, Research Funding; NovoNordisk: Consultancy, Research Funding; Bayer: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Daiichi Sanchyo: Consultancy, Honoraria; Alexion: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria.

Coagulation Factor Activity and Hemostatic Markers of Endothelial Dysfunction in Patients with Peripheral Arterial Disease

Purpose We aimed to evaluate the impact of intrinsic coagulation factors and hemostatic markers of endothelial dysfunction on complications in patients with atherosclerotic peripheral arterial disease (PAD). Materials and Methods This prospective study enrolled 120 PAD patients at Fontaine stages 2b to 3 who underwent open surgical, endovascular, or conservative treatment. Coagulation factors (FVIII, FIX, and FXI) and endothelial hemostatic markers, including von Willebrand factor (vWF) activity and level, soluble endothelial protein C receptor, and plasminogen activator inhibitor-1 (PAI-1) levels, were assessed. Results At 3 months after open bypass grafting, activity of FVIII significantly increased from a median of 175% to 233% (P<0.001). At 3 months after endovascular treatment, the activities of FVIII, FIX, and FXI significantly increased from medians of 157%, 180%, and 156% to 184%, 218%, and 181%, respectively (P<0.05). Six patients with increased FVIII activity developed bypass graft thrombosis. Four patients in the endovascular group and three patients in the conservative treatment group with increased activity of vWF developed myocardial infarction (P=0.049). The subjects who developed restenosis had increased vWF activity (P=0.023) and decreased nitric oxide metabolite levels (P=0.003). Three subjects who received conservative treatment and developed PAD progression at 12 months had increased PAI-1 activity (P=0.028). Conclusion Patients with advanced PAD had a hypercoagulable status, and performance of open or endovascular revascularization was associated with further hypercoagulability. Increased activity of coagulation factors and altered levels of hemostatic markers of endothelial dysfunction were associated with PAD complications such as graft thrombosis, myocardial infarction, disease progression, and restenosis.

Endothelial METTL3 (Methyltransferase-Like 3) Inhibits Fibrinolysis by Promoting PAI-1 (Plasminogen Activator Inhibitor-1) Expression Through Enhancing Jun Proto-Oncogene N6-Methyladenosine Modification.

METTL3 (methyltransferase-like protein 3)-mediated N6-methyladenosine modification is the most abundant RNA modification on eukaryote mRNAs and plays a crucial role in diverse physiological and pathological processes. However, whether N6-methyladenosine modification has function in thrombosis is unknown. This study aims to determine the role of METTL3 in the endothelial cells-mediated thrombosis. Approach and Results: RNA-sequencing and real-time quantitative PCR revealed that the expression of PAI-1 (plasminogen activator inhibitor-1) was downregulated in METTL3 knockdown human umbilical vein endothelial cells. In vitro experiments showed that METTL3 suppressed fibrinolysis. Mechanically, RNA methylation sequencing and meRIP-quantitative real-time PCR showed that METTL3 catalyzed N6-methyladenosine modification on 3' UTR of JUN mRNA. Western blotting analysis showed that METTL3 promoted JUN protein expression. Chromatin immunoprecipitation analysis demonstrated that JUN bound to the PAI-1 promoter in human umbilical vein endothelial cells. Furthermore, mice challenged with lipopolysaccharide resulted in higher METTL3 expression in vessels. Endothelial-specific knockdown of Mettl3 decreased expression of active PAI-1 in plasma and attenuated fibrin deposition in livers and lungs during endotoxemia. Our study reveals that METTL3-mediated N6-methyladenosine modification plays a crucial role in fibrinolysis and is an underlying target for the therapy of thrombotic disorders.