Journal of Thrombosis and Haemostasis最新文献

Introduction: Concomitant administration of activated prothrombin complex concentrate (aPCC) at doses >100 U/kg/day is associated with thrombotic risk under emicizumab prophylaxis. In vitro global assay data on the effects of concomitant coagulation-factor-agents in the presence of NXT007, an emicizumab-based engineered bispecific antibody under clinical development, may serve as a basis for addressing this potential risk.

Aim: To investigate the in vitro effects of rFVIII, rFVIIa, and aPCC during NXT007 treatment and estimate tolerable doses with reference to emicizumab.

Methods: Thrombin generation assays, clot waveform analysis, and rotational thromboelastometry (ROTEM) were performed using hemophilia A plasma and blood samples spiked with NXT007 and others.

Results: A single dose of NXT007 at ≥10 μg/mL (plasma) achieved a non-hemophiliac coagulation potential. The concomitant addition of rFVIII, rFVIIa, and aPCC each boosted various parameters following NXT007 levels at 0.1-50 μg/mL. In the co-presence of NXT007 at 15 μg/mL (blood) and aPCC at 0.13 U/mL, with the blood level immediately following the administration of 10 U/kg, the ROTEM parameters were comparable to those observed with clinical emicizumab level and aPCC at 0.63 U/mL, corresponding to the blood level immediately after administrating 50 U/kg (recommended initial dose).

Conclusions: Concomitant addition of coagulation agents increased coagulation potentials in vitro in the presence of NXT007. A dose of 10 U/kg may serve as a rough indicator for the initial dose when exploring the concomitant use of aPCC at plasma NXT007 levels of approximately 30 μg/mL. Importantly, plasma NXT007 at ≥10 μg/mL demonstrated non-hemophiliac coagulation potentials in vitro.

Background: Despite efficacious vaccines many individuals remain at risk of severe illness and death from COVID-19 due to immune-escape variants. Hence, a better understanding of biomarkers underlying COVID-19 pathophysiology is needed to improve disease progression prediction and identify new drug targets. Angiostatin is a plasmin(ogen)-derived protein generated by platelets. As microvascular thrombosis, a key pathological feature of COVID-19, can create microenvironments of both high angiostatin concentration and hypoxia/acidosis, conditions known to favour angiostatin's pro-apoptotic actions on endothelial and epithelial cells, angiostatin may be a biomarker contributing to COVID-19 pathophysiology.

Objective: To assess the role of angiostatin in COVID-19.

Methods: Plasma angiostatin concentrations were compared between COVID-19 patients and COVID-19-negative controls, as were temporal changes in plasma angiostatin in COVID-19 patients. Subsequent, mechanistic cellular studies investigated the effects of angiostatin and its neutralization on both SARS-CoV-2 infection and subsequent cell death.

Results: Plasma angiostatin concentrations increased following SARS-CoV-2 infection and remained elevated in COVID-19 patients for 21 to 28 days. Angiostatin at concentration that would be generated within a clot over 7-8 h promoted cell death in acidic microenvironments characteristic of severe COVID-19. Irrespective of pH, angiostatin reduced SARS-CoV-2 cellular entry of multiple variants by interfering with spike protein proteolysis. Selective angiostatin neutralizing peptides inhibited angiostatin-induced cell death, but not angiostatin's ability to reduce infection.

Conclusions: Angiostatin has dual roles during COVID-19, both preventing infection and promoting cell death. Selective angiostatin neutralizing peptides may be novel therapeutics for further pre-clinical evaluation in models of severe COVID-19.

Lupus anticoagulant (LAC) is a well-known laboratory test used to explore potential reasons for the prolongation of phospholipid-dependent coagulation tests. An extended clotting time in a coagulation test typically suggests a bleeding tendency, as the plasma takes longer to clot. However, a positive LAC result, defined as normalization of prolonged clotting time by adding anionic phospholipids in the system, does not necessarily imply this. In fact, quite the opposite is true: a positive LAC often strongly correlates with an increased risk of thromboembolic events. Therefore, despite being conceptually counterintuitive, LAC remains extremely valuable in routine clinical practice for identifying individuals at risk for thromboembolic events. Over the years, various factors have been recognized as potential inducers of LAC, with antiphospholipid antibodies associated with antiphospholipid syndrome (APS) playing a significant role. Today, research indicates that, among antiphospholipid antibodies, those targeting plasma proteins β₂-glycoprotein I and prothrombin are central to LAC. This article offers a historical perspective on LAC, emphasizing recent developments in anti-prothrombin antibodies, their connection to LAC, and novel detection methods. Our premise is that a deeper understanding of how anti-prothrombin antibodies contribute to LAC and the identification of subpopulations of these antibodies potentially responsible for it in thrombotic APS patients could lead to transformative advancements, offering new strategies for risk stratification and personalized treatments for patients with APS and beyond.

Background: Thrombocytopenia and altered platelet activation correlate with COVID-19 severity and mortality. COVID-19 patients have modifications of the platelet and blood circulating megakaryocytes (MK) transcriptome. Our objective was to explore the features of bone marrow MK, which remain poorly characterized in SARS-CoV-2 infected patients, particularly those with thrombocytopenia.

Methods: In this case series study, we analyzed bone marrow samples from a series of 11 COVID-19 patients with thrombocytopenia admitted to the intensive care unit for acute respiratory distress syndrome. Bone marrow sampling, aimed to explore thrombocytopenia's etiology by cytology, allowed us to document bone marrow MK behavior.

Results: A reduction in bone marrow cellularity and a decrease in the megakaryocytic lineage, were observed suggesting a central component of the thrombocytopenia. Bone marrow MK exhibited significantly increased emperipolesis and vacuolization. Moreover, transmission electron microscopy pointed to the presence of viral particles inside bone marrow MK. Immunolabeling confirmed the presence of two SARS-CoV-2 proteins, spike and Orf3a, as well as double-stranded RNA suggesting a potential viral replication cycle.

Conclusion: In this series of COVID-19 patients with thrombocytopenia we report the presence of SARS-CoV-2 in bone marrow MK as well as a decrease in MK lineage and an increase in emperipolesis.

Background: Peptidylarginine deiminase 4 (PAD4) citrullinates histones, enabling the release of neutrophil extracellular traps (NETs). While NETs capture and kill pathogens, they also drive immunothrombosis, potentially worsening sepsis outcomes. However, it remains unclear whether PAD4 deficiency is beneficial or harmful in sepsis.

Objectives: To evaluate the impact of PAD4 deficiency in a fecal-induced peritonitis (FIP) sepsis model, with and without antibiotic treatment, and incorporating fluid resuscitation and both sexes.

Methods: Wild-type and PAD4^-/- C57Bl/6 mice received intraperitoneal injections of fecal slurry (0.6 mg/g). Mice received buprenorphine every 8h and antibiotics/fluids every 12h. Survival studies were also conducted without antibiotics at a reduced fecal dose (0.4 mg/g). Mice were culled at 8h or 48h post-infection. Organs, blood, and peritoneal cavity fluid (PCF) were collected. Plasma levels of interleukin (IL)-6, IL-10, cell-free DNA, and thrombin-antithrombin were quantified, as well as bacterial loads in blood and PCF. Organ histology/immunohistochemistry was performed.

Results: Female PAD4-/- mice had worsened survival compared to female wild-type mice. Male mice exhibited worse survival than females in both strains. Antibiotics eliminated survival differences between strains and sexes. Septic PAD4^-/- mice had reduced IL-10 in the early phase of sepsis, increased lung myeloperoxidase, and exacerbated lung injury compared with septic wild-type mice.

Conclusion: PAD4 deficiency in female mice worsened survival in the FIP sepsis model. In both strains, male mice exhibited worse survival compared to their female counterparts. PAD4 deficiency is associated with reduced IL-10, increased neutrophil infiltration, and exacerbated lung injury. Antibiotics eliminated survival differences between strains and sexes.

Management of recurrent thrombotic events in patients taking a direct oral anticoagulant can be challenging. In this review, we consider causes of so-called DOAC failure, from poor adherence, malabsorption and drug interactions to the presence of undiagnosed antiphospholipid syndrome, cancer- associated thrombosis, severe thrombophilia, vasculitis and other rare causes. We discuss the known or potential pathogenesis of VTE recurrence in these situations and provide practical guidance to assist clinicians faced with these challenging cases.

Background: Stroke is a major cause of death globally, especially in type 2 diabetes (T2D) patients. Fibrinogen is known to predict stroke risk, but fibrinogen is a highly variable protein and we hypothesized that fibrinogen variants can improve stroke prediction.

Objectives: To investigate the association of total fibrinogen and fibrinogen variants with risk of ischemic stroke in T2D patients.

Methods: In a nested case-control study with a median follow-up of 4.1 years, we included 144 T2D patients with ischemic stroke (cases) and 144 matched T2D patients without ischemic stroke (controls). We measured total fibrinogen, absolute and relative levels of three fibrinogen variants (fibrinogen α_E, fibrinogen γ´, and sialylated fibrinogen) and compared levels between cases and controls. We used logistic regression to determine the association with stroke risk.

Results: Total fibrinogen and absolute levels of fibrinogen α_E, fibrinogen γ´, and sialylated fibrinogen were higher in stroke cases than controls. Absolute levels of fibrinogen positively associated with risk of stroke, both for total fibrinogen (highest vs lowest tertile; adjusted odds ratio (OR) 1.9 (95% CI 0.9-4.2)), fibrinogen γ´ (OR 1.8 (0.8-3.8)), and sialylated fibrinogen (OR 2.5 (1.1-5.8)). Relative levels of fibrinogen variants did not convincingly associate with stroke risk.

Conclusion: Patients with T2D who developed stroke had increased levels of total fibrinogen, fibrinogen α_E, fibrinogen γ´, and sialylated fibrinogen compared with T2D controls. Total fibrinogen and absolute, but not relative, levels of fibrinogen γ´ and sialylated fibrinogen prospectively associated with a 2-fold increased risk of ischemic stroke.