Journal of Thrombosis and Haemostasis最新文献

Background: While bleeding around pregnancy is well described in von Willebrand disease (VWD), risk of pregnancy loss is less certain. We aimed to describe the frequency of pregnancy loss in females with VWD, compared with those with a similar mucocutaneous bleeding phenotype and no VWD, or compared with non-bleeding disorder controls.

Methods: Female patients were consecutively approached in 8 specialty bleeding disorder clinics between 2014-2023. The VWD group was defined as having VWF:Antigen (Ag) and VWF:Activity (Act) levels, each <0.50 IU/mL on ≥2 occasions, and a Condensed MCMDM-1 score of ≥4. The non-VWD mucocutaneous bleeding disorder group had VWF levels ≥0.50 IU/mL on ≥2 occasions and a MCMDM-1 score ≥4. A non-bleeding disorder control group was recruited in pregnancy from a low-risk maternity clinic.

Results: There were 150 females in the VWD group, 145 in the non-VWD mucocutaneous bleeding disorder group, and 137 in the control group. There was a similar frequency of individuals with ≥1 loss in the VWD group (45.3%, 68/150), the non-VWD group (56.6%, 82/145) (-11.2%, 97.5% CI -24.2, 1.8%), and the non-bleeding disorder control group (37.2%, 51/137) (8.1%, 97.5% CI -4.9%, 21.1%). Using a logistic regression, the odds ratio of pregnancy losses in the VWD group versus non-VWD group was 0.94 (95% CI 0.65, 1.36). All groups experienced more recurrent losses compared to the literature.

Conclusions: There was no statistically significant difference in risk of pregnancy loss between females with VWD, females with a similar mucocutaneous bleeding phenotype, and with non-bleeding disorder controls.

Background: Protein Disulfide Isomerase (PDI) is a promising target for combating thrombosis. Extensive research over the past decade has identified numerous PDI-targeting compounds. However, limited information exists regarding how these compounds control PDI activity, which complicates further development.

Objectives: To define the mechanism of action of two allosteric antithrombotic compounds of therapeutic interest, quercetin-3-O-rutinoside and bepristat-2a.

Methods: A multi-pronged approach that integrates single-molecule spectroscopy, steady-state kinetics, single turnover kinetics, and site-specific mutagenesis.

Results: PDI is a thiol-isomerase consisting of two catalytic a-domains and two inactive b-domains arranged in the order a-b-b'-a'. The active sites CGHC are located in the a and a' domains. The binding site of quercetin-3-O-rutinoside and bepristat-2a is in the b' domain. Using a library of nine FRET sensors, we show that quercetin-3-O-rutinoside and bepristat-2a globally alter PDI structure and dynamics, leading to ligand-specific modifications of its shape and reorientation of the active sites. Combined with enzyme kinetics and mutagenesis of the active sites, FRET data reveal that binding of quercetin-3-O-rutinoside results in a twisted enzyme with reduced affinity for the substrate. In contrast, bepristat-2a promotes a more compact conformation of PDI, in which a greater enzymatic activity is achieved by accelerating the nucleophilic step of the a domain, leading to faster formation of the covalent enzyme-substrate complex.

Conclusions: This work reveals the mechanistic basis underlying PDI regulation by antithrombotic compounds quercetin-3-O-rutinoside and bepristat-2a, and points to novel strategies for furthering the development of PDI-targeting compounds into drugs.

Background: Hereditary hemorrhagic telangiectasia (HHT) is a bleeding disorder characterized by arteriovenous malformations (AVMs), commonly presenting with epistaxis and gastrointestinal bleeding. Bleeding symptoms may be difficult to manage and may become life-threatening, with many patients developing dependence on parenteral iron and/or blood transfusion. There is a growing body of evidence that antiangiogenic therapies may be effective in management of bleeding symptoms, presumably targeting pathogenic HHT pathways such as vascular endothelial growth factor (VEGF) receptor.

Objectives: To report single-center, retrospective real-world use of pazopanib, an orally administered tyrosine kinase inhibitor that blocks VEGF receptors, in six patients with HHT-associated epistaxis and/or gastrointestinal (GI) bleeding.

Patient/methods: A retrospective observational analysis was performed to assess the safety/efficacy of pazopanib use in patients with confirmed HHT-associated epistaxis and/or GI bleeding between 01 January 2019 and 14 June 2023 The Indiana Hemophilia and Thrombosis (IHTC) institutional EMR was queried for HHT patients who were treated with pazopanib for >3 months. Patient data were obtained from patient documentation, physician/nursing notes, and on-call documentation Institutional IRB approval was obtained for data pull as an exempt study RESULTS AND CONCLUSIONS: Our observations on the real-world use of pazopanib in six HHT patients with moderate to severe bleeding showed improvement in hemoglobin levels, with reduction in iron infusions and red blood cell transfusion requirement. Pazopanib may be a reasonable option for patients with HHT with epistaxis or gastrointestinal bleeding that are refractory to standard treatment.

Background: Inherited platelet diseases (IPDs) are bleeding disorders characterized by either defect in platelet count or in platelet function, the latter being less common and very heterogeneous. Numerous gene variants associated with abnormal receptors, granules, and signaling pathways have been reported. Despite significant advancements in our understanding, many patients still lack a precise diagnosis.

Objectives: To identify the genetic basis of a novel mild bleeding syndrome in a family exhibiting a selective defect of platelet aggregation.

Patients/methods: Our study included 6 family members across three generations, who displayed reduced platelet aggregation in response to ADP, PAR1-AP, arachidonic acid, and epinephrine, but not collagen. Platelet morphology, granule content and expression of major surface glycoproteins were all found to be normal. Whole exome sequencing was performed for affected and non-affected family members.

Results and conclusions: We identified RGS18, which encodes the regulator of G protein signaling (RGS) 18, as a candidate gene for the platelet function defect observed in this family. The RGS18 protein serves as a crucial negative regulator of G protein-coupled receptor (GPCR) signaling and coordinates the signaling pathways of natural platelet inhibitors. The heterozygous RGS18 c.643C>T, p.Arg215* variant was found to co-segregate among all six affected subjects. Truncation at Arg215 removes the S216 and S218 phosphorylation sites, which are crucial regulatory domains for RGS18 activation. The impaired platelet function is thought to arise from excessive platelet downregulation due to constitutive activation of RGS18, resulting from a loss of association of the truncated form with the 14-3-3 protein.

Introduction: Managing older patients with acute pulmonary embolism (PE) is challenging due to their underrepresentation in clinical trials, comorbidities and increased complication risk. This study evaluates risk assessment and management outcomes in older PE patients focussing on home and reperfusion treatment.

Methods: A retrospective analysis was conducted on patients aged ≥70 years diagnosed with acute PE at an academic medical centre (2015-2022).

Results: 242 patients with a mean age of 77 years were included. All 59 patients with negative Hestia criteria were discharged ≤24h, and in total 81 patients (35%) received home treatment. Among these 14-day mortality and recurrent venous-thromboembolism were 0% and major bleeding occurred in 1.3% (one patient, 95%CI 0.11-6.1). European Society of Cardiology (ESC) risk-classification showed 9 low-risk PE (3.9%), 199 intermediate-risk (87%), and 20 high-risk PE patients (8.8). In 5 of the 20 high-risk patients, hypotension was mainly caused by another condition, i.e. sepsis. Eight high-risk patients received reperfusion therapy. Fourteen-day mortality was 51% in high-risk patients (95%CI 27-71); 5 out of 8 patients receiving reperfusion treatment died within 5 days. Patients with an Acute Presenting Older Patient (APOP) score of ≥45% had higher 14-day mortality (28%; 95%CI 12-46) compared to <45% (3.2%; 95%CI 0.85-8.3; HR 10.2; 95%CI 2.6-39).

Conclusion: Selecting for home treatment using Hestia was safe for older PE patients in our cohort. Mortality in the high-risk group was high also when receiving reperfusion treatment. The ESC risk-classification and APOP score identified patients at higher mortality risk, suggesting their potential utility in clinical decision-making.

Background: Deep vein thrombosis (DVT) is a major cause of morbidity and mortality globally. While its pathophysiology is complex, increasing evidence suggests a more prominent role for platelets than previously suspected. Genetic deletion of Ral GTPases, RalA and RalB, conditionally in mouse platelets (RalAB DKO), results in a near complete defect in P-selectin externalisation upon activation, while other platelet activation responses and arterial thrombosis are preserved.

Objective: Given the critical role of P-selectin in mediating platelet-neutrophil interaction and thromboinflammation, we sought to investigate whether platelet Rals would also play critical roles in venous thrombosis, a thromboinflammatory disease, using RalAB DKO mice.

Methods: DVT was induced by surgical partial ligation of the caudal (inferior) vena cava for 24-h or 48-h before venous thrombi were assessed by histology and immunofluorescence microscopy.

Results: RalAB DKO mice show a reduction in venous thrombus formation after 24-h, and near complete ablation of venous thrombosis by 48-h post IVC ligation. Immunofluorescence microscopy revealed that cross sections of thrombi from wildtype mice consist of an organised scaffolded structure of platelets surrounding leukocytes/neutrophils producing NETs to stabilize and propagate the thrombus. This organised structure was absent in platelet-specific conditional RalAB DKO thrombi. In vitro analysis of platelet-mediated NET formation was also significantly reduced when platelets lacked RalAB or when platelets were treated with the Ral inhibitor RBC8.

Conclusion: We identify platelet Rals as novel, potentially critical regulators of venous thrombus stability, through their ability to regulate neutrophil NET formation via platelet P-selectin.

Background: Acute large vessel occlusion (LVO) stroke is highly prevalent and severe. Despite thrombolytic therapy, many patients experience substantial complications. Understanding the origins, constituents, and pathological processes involved in thrombus formation in acute intracranial large artery occlusion is crucial.

Objectives: To identify the characteristics of insoluble proteins from different sources of cerebral thrombus.

Methods: This study included 13 patients with cardiogenic embolic thrombus (CE) and 15 with large artery atherosclerosis thrombus (LAA). High-performance liquid chromatography and liquid chromatography-tandem mass spectrometry were used to analyze insoluble proteins in thrombi. Bioinformatics analyses explored differential proteins and associated functional pathways. Least Absolute Shrinkage and Selection Operator and Random Forest identified biomarkers for diagnosing thrombus sources, validated by parallel reaction monitoring.

Results: We constructed an insoluble protein atlas of cerebral thrombi, identifying 6975 insoluble proteins, including 143 extracellular matrix (ECM)-related proteins. The enrichment pathways considerably varied between thrombi from different sources. Inflammation-related pathways, such as "acute inflammatory response," along with ECM-related pathways such as "laminin interactions," were notably upregulated in LAA compared to CE. Additionally, two biomarkers (IDH2, HSPG2) exhibited strong diagnostic performance (AUC = 1) and robustness.

Conclusions: In the insoluble Proteomics of thrombus, we highlighted the crucial roles of immune responses and ECM proteins in thrombus formation, providing new insights into its mechanisms and potential drug development. Additionally, we identified two biomarkers that offer new methods for determining thrombus sources in patients with LVO.

Background: Non-immunogenic staphylokinase is a modified recombinant staphylokinase with low immunogenicity, high thrombolytic activity, and fibrin selectivity.

Aim: To assess the safety and efficacy of a single intravenous bolus of non-immunogenic staphylokinase compared to those of alteplase in patients with massive pulmonary embolism and haemodynamic instability.

Patients and methods: A randomised, open-label, multicentre, parallel-group, non-inferiority trial, the FORPE was conducted in Russia. A total of 310 patients aged 18 years and older with computed tomography pulmonary angiography confirmed diagnosis of massive pulmonary embolism and right ventricular dysfunction were included. The patients were randomly assigned to receive either non-immunogenic staphylokinase (15 mg) or alteplase (100 mg), both administered intravenously. The primary efficacy endpoint was death from all causes within seven days of randomisation.

Results: A total of 155 patients were randomly assigned to receive non-immunogenic staphylokinase, and 155 received alteplase. In the non-immunogenic staphylokinase group, the primary efficacy endpoint was 2% in the intention-to-treat population, while in the alteplase group it was 3% (odds ratio [OR] 0.75, 95% confidence interval [CI] 0.11 to 4.49; p=1.00). The difference in the primary efficacy endpoint was 0.6% (95%CI -2.8 to 4.0). Thus, the lower limit of the 95%CI did not cross the margin of non-inferiority. No cases of major bleeding were recorded in the non-immunogenic staphylokinase group, whereas there were five cases of major bleeding (3%, p=0.09) in the alteplase group.

Conclusions: Non-immunogenic staphylokinase was non-inferior to alteplase in patients with massive pulmonary embolism. Future observational studies are needed to assess it safety and efficacy.

Background: Myocardial ischemia-reperfusion (MI/R) injury tends to affect cardiac function and leads to poor patient prognosis, and there is still no effectively targeted drug to develop anti-von Willebrand factor (VWF) aptamer in acute coronary heart disease. However, the newly anti-VWF aptamer BT200 is applied not only for stroke and hemophilia but also for antithrombolism function in clinical development. The role of BT200 in acute myocardial injury during MI/R is still unknown.

Objectives: To investigate the cardioprotective effect of aptamer BT200 in a mouse model of MI/R.

Methods: C57BL/6 mice were subjected to 30-minute ischemia and 24-hour reperfusion to establish MI/R model. Mice were treated with intravenous injection of cy3-labeled BT200 and were observed by an in vivo imaging system at different time points. Then, mice were sampled and evaluated by echocardiography, Evans triphenyltetrazolium chloride staining, histopathologic, western blotting, and real-time quantitative polymerase chain reaction assays to detect cardiac injury and inflammation response after 24-hour reperfusion.

Results: BT200 aptamer can enter and infiltrate into the ischemic myocardium after 24-hour reperfusion. BT200 was shown to inhibit VWF A1 activity and prolong bleeding time in MI/R mice. Moreover, BT200-treated mice had a significant reduction in infarct size and an improvement in cardiac function post-MI/R. BT200 treatment can also alleviate MI/R-induced microvascular obstruction, inflammation response, and cardiomyocyte apoptosis.

Conclusion: Pharmacologic targeting of VWF with BT200 alleviates acute MI/R injury in a murine model and may be a novel therapy strategy for acute myocardial infarction.

Background: The vascular endothelial cell (EC) monolayer plays a crucial part in maintaining hemostasis. An extensive array of G protein-coupled receptors allows ECs to dynamically act on key hemostatic stimuli such as thrombin and histamine. The impact of these individual stimuli on EC signal transduction has been the subject of various studies, but insight into discordant and concordant EC signaling between different G protein-coupled receptors remains limited.

Objectives: To elucidate histamine and protease-activated receptor (PAR1-4) signaling cascades in ECs, discern overlapping and diverging regulation between these stimuli and their effect on the EC monolayer.

Methods: We employed stable isotope labeling by amino acids in cell culture mass spectrometry-based phosphoproteomics on in vitro cultured blood outgrowth ECs stimulated with histamine and different PAR1 to 4 peptides. We investigated key phosphosites through immuno(fluorescence) staining and determined effects on barrier function through transendothelial resistance assays.

Results: EC histamine activation initiated an extensive (kinase) signaling network (including MAPK3, STAT3, and CTNND1). PAR1 and PAR2 receptors induced highly similar signaling cascades, whereas PAR3 and PAR4 induced minimal phospho-regulation. Integration of all applied stimuli indicated uniquely activated proteins between both stimuli, as well as a general overlapping activation of cell junction and actin cytoskeletal proteins.

Conclusion: We provide an integrative phosphoproteomic analysis of histamine and PAR agonists in the endothelium that highlights the endothelial response programs that are at the basis of regulating hemostasis.