Search Results (224)

(1) Background: The presence of metastatic disease significantly increases the risk of venous thromboembolism (VTE) in breast cancer, particularly during chemotherapy. Although not categorized as a highly thrombogenic malignancy, the elevated global prevalence of this cancer places a substantial number of patients at risk of thrombosis, which cannot yet be accurately predicted by validated risk assessment models (RAMs), highlighting the need for a dedicated model. (2) Aim: This study aims to develop a RAM for VTE in newly diagnosed metastatic breast cancer patients enrolled in a prospective, observational, and multicenter study. (3) Methods: A cohort of 189 patients beginning antitumor therapy were enrolled and prospectively monitored for VTE and mortality. Blood samples collected at enrollment were tested for D-dimer, fibrinogen, FVIII, prothrombin fragment 1 + 2 (F1 + 2), and thrombin generation (TG). Competing risk analyses were performed to identify significant predictors. (4) Results: Within one year, the cumulative incidences of VTE and mortality were 7.0% and 12%, respectively. Univariable analysis identified high Ki-67, D-dimer, FVIII, fibrinogen, and TG levels, along with low hemoglobin levels, as independent predictors of VTE. Only Ki-67, fibrinogen, FVIII, and hemoglobin were retained as significant predictors in multivariable analysis. These variables were further examined by multiple linear regression, which revealed Ki-67 and fibrinogen as the most significant parameters. A continuous RAM was then developed based on Ki-67 and fibrinogen (c-statistics 0.78), categorizing patients into low-risk and high-risk groups for VTE (2% vs. 13%; SHR 3.6, p = 0.018). This stratification could not be achieved using currently validated models for VTE risk. (5) Conclusions: We developed an accurate RAM for VTE that enables the identification of metastatic breast cancer patients at high risk for VTE, which supports clinicians in personalized thromboprophylaxis strategies if externally validated. Full article

Venoms of the Palearctic vipers in the Macrovipera genus cause severe procoagulant clinical effects, yet the precise molecular targets remain incompletely defined. To fill this toxicological knowledge gap, we tested five Macrovipera venoms—M. lebetina cernovi, M. l. obtusa, M. l. turanica (Turkmenistan and Uzbekistan localities), and M. schweizeri—using plasma clotting assays, Factors VII, X, XI, and XII and prothrombin zymogen activation assays, and SDS-PAGE to visualise Factor V (FV) cleavage. All venoms induced extremely rapid clot formation (10.5–12.5 s) compared with the negative control (spontaneous clotting) of 334.6 ± 3.6 s) and the positive control (kaolin trigger) of 55.8 ± 1.9 s. Activation of FVII or FXI was negligible, whereas consistent FX activation and species-variable FXII activation, both moderate, were observed. Prothrombin remained inert in the absence of cofactors, but the presence of FV or FVa elicited potent thrombin generation. SDS-PAGE confirmed proteolytic conversion of the 330 kDa FV zymogen into the ~105 kDa heavy and ~80 kDa light chains of FVa by the venoms of all species. This data demonstrates that Macrovipera venoms rely on a dual enzyme strategy: (i) activation of FV to FVa by serine proteases and (ii) FVa-dependent prothrombin activation by metalloproteases. These results reveal that prothrombin activation is the dominant procoagulant pathway and overshadows the historically emphasised FX activation. This mechanism mirrors, yet is evolutionarily independent from, the FXa:FVa prothrombinase formation seen in Australian elapid venoms, highlighting convergent evolution of cofactor-hijacking strategies among snakes. The discovery of potent FVa-mediated prothrombin activation in Macrovipera challenges existing paradigms of viperid venom action, prompts re-evaluation of related genera (e.g., Daboia), and underpins the design of targeted antivenom and therapeutic interventions. Full article

Platelets play critical roles in haemostasis and thrombosis. The platelet activation process is driven by agonist-induced rises in cytosolic [Ca²⁺]_i, where the patterns of Ca²⁺ responses are still incompletely understood. In this study, we developed a number of techniques to model the [Ca²⁺]_i curves of platelets from a single blood donor. Fura-2-loaded platelets were quasi-simultaneously stimulated with various agonists, i.e., thrombin, collagen, or CRP, in the presence or absence of extracellular Ca²⁺ entry, secondary mediator effects, or Ca²⁺ reuptake into intracellular stores. To understand the calibrated time curves of [Ca²⁺]_i rises, we developed two non-linear models, a multilayer perceptron (MLP) network and an autoregressive network with exogenous inputs (NARX). The trained networks accurately predicted the [Ca²⁺]_i curves for combinations of agonists and inhibitors, with the NARX model achieving an R² of 0.64 for the trend prediction of unforeseen data. In addition, we used the same dataset for the construction of a partial least square (PLS) linear regression model, which estimated the explained variance of each input. The NARX model demonstrated that good fits could be obtained for the nanomolar [Ca²⁺]_i curves modelled, whereas the PLS model gave useful interpretable information on the importance of each variable. These modelling results can be used for the development of novel platelet [Ca²⁺]_i-inhibiting drugs, such as the drug 2-aminomethyl diphenylborinate, blocking Ca²⁺ entry in platelets, or for the evaluation of general platelet signalling defects in patients with a bleeding disorder. Full article

Procoagulant platelets are a specialized subset of activated platelets that externalize phosphatidylserine (PS) on their surface, facilitating the assembly of tenase and prothrombinase complexes and enhancing thrombin generation and clot formation. Although procoagulant platelet formation shares certain features with nucleated cell death pathways, such as mitochondrial dysfunction, calcium (Ca²⁺) overload, membrane blebbing, and microvesiculation, it differs in key molecular mechanisms, notably lacking nuclei and caspase-dependent deoxyribonucleic acid (DNA) fragmentation. Interestingly, molecular components of nucleated cell death pathways in platelets can promote thrombus formation without impacting platelet lifespan. Under pathological conditions, excessive platelet activation may result in platelet lysis, resembling the complete activation of nucleated cell death pathways and contribute to thrombocytopenia. This review compares procoagulant platelet formation with various nucleated cell death pathways, including necrosis, necroptosis, pyroptosis, and ferroptosis, and explores their role in pathological thrombosis and blood clotting. A deeper understanding of mechanisms may help in developing targeted therapies to prevent aberrant blood clotting, platelet death and thrombocytopenia. Full article

Heparin, a widely used polysaccharidic anticoagulant of animal origin, is associated with risks of contamination and adverse effects, notably bleeding and thrombocytopenia. These limitations have prompted interest in alternative sulfated polysaccharides with anticoagulant properties and improved safety profiles. This study explored the anticoagulant potential of two marine bacterial exopolysaccharides (EPS), infernan and diabolican. It assessed whether chemical modifications (depolymerization, oversulfation) could enhance their anticoagulant properties compared to unfractionated and low molecular weight heparins. Native EPS were depolymerized to generate different molecular weights and then chemically oversulfated to increase negative charge density. Anticoagulant activities were evaluated using clotting and thrombin generation assays (TGA). Molecular docking was performed to model interactions with antithrombin and heparin cofactor II. Only highly sulfated derivatives significantly prolonged activated partial thromboplastin time while showing negligible effect on thrombin time and anti-factor Xa activity. They present different structures, and their binding to antithrombin is not achieved via the classic pentasaccharide motif. In TGA, these derivatives inhibited thrombin formation at higher doses than heparin but induced a marked delay in clot generation. Docking analyses supported their ability to bind serpins, albeit with lower specificity than heparin. Their limited anti-Xa activity and non-animal origin position them as promising anticoagulant candidates. Full article

Phosphatidylserine (PS) is an essential phospholipid and an emerging biomarker involved in key biological processes. While annexin V (axV) is the most widely used tool for PS detection, its calcium-dependent binding and other limitations have spurred interest in alternative probes. The lactadherin C2 domain (lactC2) offers a promising alternative, addressing many of the drawbacks associated with axV. However, its broader adoption has been hindered by challenges in production and modification for convenient experimental use. Here, we demonstrate the successful in-house engineering of fully functional recombinant bovine lactC2-based fluorescent sensors and compare their key parameters to axV probes. We show that mNeonGreen–lactC2 fusion exhibits calcium-independent binding with a comparable dissociation constant for 20% PS liposomes. We also demonstrate the detrimental effects of primary amine modification on lactC2’s PS binding efficiency, suggesting the preferential use of fluorescent protein fusion or alternative approaches. Finally, we show that unlike full-length lactadherin or axV, lactC2 inhibited thrombin generation only at high concentrations (>250 nM) in coagulation assays. These findings establish recombinant lactC2 as a versatile and promising PS sensor, with potential applications in experimental settings where axV might be unsuitable Full article

Pneumonia is the most common cause of sepsis, with Klebsiella pneumoniae frequently implicated as a causative pathogen. Platelets play a crucial role in host defense during sepsis, and their activation is essential for effective immune responses, which is at least in part induced through activation of the collagen receptor glycoprotein (GP)VI. Platelets require energy for their activation, and Liver kinase B1 (LKB1) is a key regulator of energy metabolism. We sought to determine the role of LKB1 in platelet function and host response during K. pneumoniae-induced pneumosepsis. Platelet-specific-Lkb1-deficient mice were generated and compared to control littermates. Platelet counts were unaffected by Lkb1 deficiency in naïve mice. However, Lkb1-deficient platelets exhibited significant hyperreactivity to GPVI stimulation, an effect not observed after stimulation of the thrombin receptor protease-activated receptor 4. During K. pneumoniae infection, platelets of both Lkb1-deficient and control mice became equally hyporesponsive to GPVI stimulation, without differences between genotypes. Platelet-specific Lkb1 deficiency did not alter bacterial outgrowth or dissemination, inflammatory responses, or lung pathology. These findings suggest that while Lkb1 plays a role in regulating platelet activation in response to GPVI stimulation, it does not significantly impact platelet activation or the host response during pneumonia-induced sepsis. Full article

Osteopontin (OPN), a matricellular protein, is produced as a full-length OPN (FL-OPN) and cleaved by thrombin, thus generating the N-terminal half of OPN (OPN N-half) with new functions. Although plasma FL-OPN levels have been associated with neurovascular events after aneurysmal subarachnoid hemorrhage (SAH), plasma OPN N-half levels have never been investigated. In this study, prospective clinical data and plasma samples were collected from 108 consecutive SAH patients with ruptured aneurysms undergoing acute treatment via surgery, and FL-OPN and OPN N-half levels were measured in plasma with a particular focus on delayed cerebral infarction (DCIn), which has the greatest impact on outcomes. Plasma FL-OPN and OPN N-half levels were intercorrelated and significantly higher in patients with DCIn at days 10–12 post-SAH; a greater area under the receiver-operating characteristic curve was observed for OPN N-half levels, with a cut-off value of 70.42 pmol/L. Multivariate analyses revealed that plasma OPN N-half levels of ≥70.42 pmol/L at days 10–12 were independently associated with DCIn development (adjusted odds ratio, 5.65; 95% confidence interval, 1.68–18.97; p = 0.005). Based on the findings of this study and previous reports, an increase in the OPN N-half level may be indicative of a protective mechanism against DCIn development, and, thus, it holds promise as a new therapeutic target against DCIn after aneurysmal SAH. Full article

Cardiovascular diseases, including thrombosis, are the leading cause of mortality worldwide. The generation of monoclonal antibodies (mAb) targeting specific coagulation factors could provide more targeted and safer anticoagulant therapies. Factor V (FV) is a critical cofactor in the prothrombinase complex, which catalyzes the conversion of prothrombin to thrombin, a key enzyme in the coagulation cascade. We isolated a novel human antibody specific to FV by using phage display technology. The selection occurred by panning a large repertoire of phages expressing human antibody fragments (scFv) in parallel on the purified recombinant protein in its native form (FV) or activated by proteolytic maturation (Factor Va (FVa)). Through ELISA screening, we identified the clone with the highest binding affinity for both targets, and it was successfully converted into IgG1. The novel human mAb, called D9, was found capable of binding to Factor V with a low nM affinity both by ELISA and BLI assays, whereas its cross-reactivity with some other coagulation factors was found null or very poor. Furthermore, when tested in blood clotting tests, it was found able to prolong activated partial thromboplastin time (aPTT). Thus, D9 could become not only a potential therapeutic agent as a specific anticoagulant but also a precious tool for diagnostic and research applications. Full article

Background and Objectives: With the increasing life expectancy, the frequency of total thyroidectomies in elderly patients has risen, raising concerns regarding hemorrhage and recurrent laryngeal nerve palsy compared to the general population. Therefore, considering the frequent alteration of the coagulation status in such patients, innovative methods able to reach an accurate hemostasis appear highly desirable. This retrospective multicentric study aimed to compare the postoperative outcomes of patients treated with conventional hemostasis with patients treated with the Harmonic Scalpel (HS) and gelatin–thrombin matrix (Floseal). Materials and Methods: Patients undergoing total thyroidectomy were retrospectively enrolled and categorized into two groups: Group A patients underwent surgery with the Harmonic Scalpel and Floseal, while Group B underwent traditional hemostasis surgery with ligations and monopolar electrocautery. The primary endpoint was the drain output after 24 and 48 h and the presence of significant blood loss. Secondary endpoints included the presence of seroma, wound infection, hematoma, laryngeal nerve palsy, surgery duration, and onset of post-surgical hypocalcemia. Results: From January 2014 to January 2024, 870 individuals participated in the study. Group A (gelatin–thrombin and HS) comprised 502 patients, while Group B (Standard Hemostasis—control group) comprised 368 patients. The 24 h drain output was 52 ± 25 mL in Group A vs. 113 ± 27 mL in Group B, p = 0.003, while the 48 h drain output was 95 ± 29 mL in Group A and 113 ± 27 mL in Group B (p = 0.002). Significant blood loss occurred in eight patients (2.2%) of Group B vs. three cases (0.6%) in Group A (p = 0.039). Also, neck hematoma (p = 0.012), seroma (p = 0.005), and reoperation (p = 0.052) values were significantly lower in Group A. Conclusions: Surgery aided with HS, and gelatin–thrombin was associated with lower major and minor complications compared to the conventional approach, guarantying reduced operative time, ensuring hemostasis, and preserving parathyroid glands, even in elderly patients. Full article

Hemorrhage, particularly non-compressible torso bleeding, remains the leading cause of preventable death in trauma. Self-propelling hemostats composed of thrombin-calcium carbonate (CaCO₃) particles and protonated tranexamic acid (TXA⁺) have been shown to reduce blood loss and mortality in severe bleeding animal models. To further enhance both hemostatic and self-propelling properties, this study was to investigate fibrinogen-CaCO₃ particles prepared via a water-oil-water (W/O/W) emulsion method. The particles were characterized using light and fluorescence microscopy, gel electrophoresis, rotational thromboelastometry (ROTEM), and video motion tracking. The method produced spherical micrometer-sized particles with various yields and fibrinogen content, depending on the preparation conditions. The highest yield was achieved with sodium carbonate (SC), followed by ammonium carbonate (AC) and sodium bicarbonate (SBC). AC and paraffin generated smaller particles compared to SC and heptane, which were used as the carbonate source and oil phase, respectively. Fibrinogen incorporation led to an increase in particle size, indicating a correlation between fibrinogen content and particle size. Fluorescence microscopy confirmed successful fibrinogen encapsulation, with various amounts and hemostatic effects as assessed by gel electrophoresis and ROTEM. Combining fibrinogen-CaCO₃ particles with TXA⁺ and thrombin-CaCO₃ particles showed synergistic hemostatic effects. All fibrinogen-encapsulated particles exhibited self-propulsion when mixed with TXA⁺ and exposed to water, regardless of fibrinogen content. This study advances current hemostatic particle technology by demonstrating enhanced self-propulsion and fibrinogen incorporation via the W/O/W emulsion method. Further optimization of the encapsulation method could enhance the effectiveness of fibrinogen-CaCO₃ particles for hemorrhage control. Full article

Background: Patients with cancer often develop a prothrombotic state that can evolve into venous and arterial thrombosis, which is associated with poor clinical outcomes. Glioblastoma multiforme (GBM) is the most frequently associated with thrombosis, but the underlying causes of this prothrombotic state are poorly defined. Objectives: We designed a study to characterize the expression of coagulation factor X (FX) and its alternatively spliced transcripts in glioblastoma tissues surgically removed from patients and in clonal cell lines. Methods: The F10 mRNA and FX protein were quantified in tissues surgically removed from seven patients with glioblastoma (glioma grade 3–4) and those from non-tumor patients. Glioblastoma cells from three human clonal lines were examined for the expression and secretion of FX at baseline and after the cells were stimulated with lipopolysaccharide (LPS) or subjected to oxygen/glucose starvation in culture. PCR products were subjected to Sanger sequencing and amplicon sequencing to identify F10 isoforms and their ratios. A chromogenic assay was performed to assess FX activity. Results: Glioblastoma tissue and cell lines expressed high levels of the full-length and an alternatively spliced F10 mRNA. The latter produced a C-terminal truncated FX. The ratio of full-length to truncated F10 transcripts was significantly higher in normal brain tissues than in glioblastoma tissue. In cultured cells from the glioblastoma cell lines, FX was secreted to the conditioned medium and was active in cleaving a chemical substrate. The FX expression and secretion were upregulated in cells stimulated with LPS or subjected to oxygen/glucose starvation. Discussion: Glioblastoma cells synthesize and secrete FX that was active in promoting thrombin generation. These findings provide a new underlying mechanism to explain why glioblastoma patients are prone to developing thrombosis. Full article

Background: The lingering effects of SARS-CoV-2 infection, collectively known as post-COVID syndrome (PCS), affect a significant proportion of recovered patients, manifesting as persistent symptoms like fatigue, cognitive dysfunction, and exercise intolerance. Increasing evidence suggests that endothelial dysfunction and coagulation abnormalities play a central role in PCS pathophysiology. This study investigates hypercoagulability and endothelial dysfunction in PCS through thrombin generation and the von Willebrand factor (VWF)/ADAMTS13 axis. Methods: Plasma samples from 97 PCS patients recruited since October 2020 by the clinical research unit of the Brugmann University Hospital were analyzed. A thrombin generation test was performed on a St-Genesia^® analyzer (Stago) using the Thromboscreen kit; VWF antigen was determined on a CS-2500 analyzer (Siemens); and ADAMTS-13 activity was determined using an ELISA kit (Technozym^®) on an ElX808 plate reader. Results: Thrombin generation testing revealed elevated thrombin production in PCS patients, particularly when thrombomodulin was included. Although most PCS patients showed normalized VWF/ADAMTS13 ratios, 11.3% exhibited elevated ratios (≥1.5), associated with advanced age. Conclusions: Patients with PCS show a consistent pattern of prolonged thrombo-inflammatory dysregulation, highlighted by elevated in vitro thrombin generation and the persistence of abnormal VWF/ADAMTS-13 ratios in a subset of patients. Full article

Background: Prostaglandins are naturally occurring local mediators that can participate in the modulation of the cardiovascular system through their interaction with Gs/Gi-coupled receptors in different tissues and cells, including platelets. Thrombin is one of the most important factors that regulates platelet reactivity and coagulation. Clinical trials have consistently shown that omega-3 fatty acid supplementation lowers the risk for cardiovascular mortality and morbidity. Since omega-3 fatty acids are the main precursors of PGE3 in vivo, it would be relevant to investigate the effects of PGE3 on Thrombin Receptor Activating Peptide (TRAP-6)-induced platelet reactivity to determine the receptors and possible mechanisms of action of these compounds. Methods: We have measured platelet aggregation, P-selectin expression, and vasodilator-stimulated phosphoprotein (VASP) phosphorylation to evaluate platelet reactivity induced by TRAP-6 to determine the effects of PGE3 on platelet function. Results: We assessed the ability of DG-041, a selective prostanoid EP3 receptor antagonist, and of ONO-AE3-208, a selective prostanoid EP4 receptor antagonist, to modify the effects of PGE3. PGE3 inhibited TRAP-6-induced platelet aggregation and activation. This inhibition was enhanced in the presence of a Gi-coupled EP3 receptor antagonist and abolished in the presence of a Gs-coupled EP4 receptor antagonist. The effects of PGE3 were directly related to changes in cAMP, assessed by VASP phosphorylation. Conclusions: The general effects of PGE3 on human platelet reactivity are the consequence of a balance between activatory and inhibitory effects at receptors that have contrary effects on adenylate cyclase. These results indicate a potential mechanism by which omega-3 fatty acids underlie cardioprotective effects. Full article

Inherited factor VII deficiency is the most common rare bleeding disorder, affecting about 1/500,000 individuals without gender predilection. Most of the patients with FVII 20–50% are asymptomatic, but post-traumatic or post-surgical bleeding may often occur since there is not an exact correlation between FVII plasma levels and the bleeding phenotype. We enrolled 19 children and adolescents with FVII levels of 20–35% and 33 controls. Laboratory data collected included thrombin generation, prothrombin time, activated partial thromboplastin time, fibrinogen, and FVII levels. In our study, we found a statistical difference in the lag time ratio (p < 0.01) and tt-peak ratio (p < 0.05) between patients and controls but no difference in the other parameters, such as the endogenous thrombin potential (ETP). However, when we categorized patients, regardless of their bleeding scores, as presenting symptoms and having no symptoms, both the lag time ratio (p = 0.01) and tt-peak ratio (p < 0.05) were significantly different, and the vel. index % showed increased levels in patients without symptoms (p < 0.05). This study shows that thrombin generation may be a useful tool in assessing the risk of bleeding symptoms in children with an FVII deficiency categorized in the mild category (20–35%), although we cannot predict the severity of the bleeding. Full article