Journal of Thrombosis and Haemostasis最新文献

A 56-year-old woman required urgent cardiac surgery for Streptococcus mitis mitral valve infective endocarditis complicated by severe autoimmune HIT (aHIT). We reasoned that the combination of high-dose IVIG (to mitigate aHIT antibody-mediated platelet activation in the presence of heparin) together with the high concentrations of heparin attained during cardiac surgery (which typically produce less platelet activation in-vitro versus usual therapeutic heparin concentrations) might prove effective. Accordingly, our patient underwent cardiac surgery with heparin following high-dose IVIG (1g/kg×2), without intra- or postoperative thrombosis. Serial serotonin-release assays, using blood obtained pre-/post-IVIG, showed minimal platelet activation (∼30% serotonin-release) post-IVIG at heparin concentrations typically obtained during cardiac surgery (2-5 U/mL), and significantly less than pre-IVIG serum in heparin's absence (∼85% serotonin-release). In the setting of urgent cardiac surgery, preoperative high-dose IVIG appears to be a reasonable strategy to reduce platelet-activating effects of HIT (including aHIT) antibodies, permitting safe use of standard intraoperative heparin dosing.

Background and aims: Immediate factor Xa (FXa) inhibition exerts direct antiplatelet effects in the context of arterial thrombosis but little is known about the impact of long-term therapy on platelet function in ischemic cardiovascular diseases.

Methods: We evaluated the effect of acute versus chronic FXa inhibition on thromboinflammation following acute myocardial infarction (AMI) and stroke in mice in vivo. Mechanistically, we identified changes in platelet gene expression and proteome under chronic FXa NOAC and characterized its functional consequence on platelet physiology. In a prospectively recruited cohort of AMI patients, we determined CMR based cardiac endpoints under FXa NOAC effects on clinical endpoints in a cohort of AMI patients.

Results: Chronic but not acute FXa inhibition reduced cerebral and myocardial infarct size and improved cardiac function 24h after AMI in mice. Mechanistically, we identified an attenuated thromboinflammatory response with reduced NET formation in mice and patient samples. Proteome and RNA expression analysis of FXa-inhibitor treated patients revealed a reduction of key regulators within the membrane trafficking and secretion machinery hampering platelet alpha and dense granule release. Subsequent, thromboinflammatory NET density in thrombi isolated from stroke and myocardial infarction patients was reduced. AMI patients treated with FXa inhibitors showed decreased infarct size after myocardial infarction compared to patients without anticoagulation treatment.

Conclusions: Long-term FXa inhibition induces anti-thromboinflammatory proteome signatures in platelets, improving infarct size after myocardial infarction and stroke.

Background: Immune-mediated thrombotic thrombocytopenic purpura (iTTP) patients are not responsive to standard rituximab in approximately 10-15% of cases, and oral immunosuppressants showed controversial results with significant toxicity. Targeting plasma cells with bortezomib appears promising, but available evidence is scarce and stems only from isolated reports in the pre-caplacizumab era.

Objectives: To evaluate the safety and efficacy of bortezomib in rituximab-refractory iTTP patients.

Methods: We conducted a retrospective observational multicenter study among 13 Italian iTTP-treating centers, collecting data from May 2017 to May 2023 (caplacizumab licensed in Italy in January 2020).

Results: Bortezomib was effective in 10/17 patients (59%). Eleven were treated in the acute phase (9/11 responders, 82%, allowing discontinuation of caplacizumab in 5/6 treated patients), and 7 during clinical remission (2/7 responders, 28%). Responses occurred at a median time of 30 days, but 3 patients responded after 4 months. The median duration of response was 22 months (IQR 10-38), still ongoing in 6 patients at the time of data cut-off. Responders had fewer previous acute iTTP episodes than non-responders [median (IQR) 1 (1-2) vs 5.5 (2-7), p=0.03]. Eight subjects (47%) reported toxicities, mostly in those treated with ≥2 cycles.

Conclusion: Durable responses to bortezomib were registered in about 60% of multi-refractory iTTP patients, with mild-to-moderate toxicities. The occurrence of late responses (i.e., after 30 days) suggests a "watchful waiting" approach after bortezomib treatment.

Background: Following proteolytic activation, activated blood coagulation factor VIII (FVIIIa) binds to activated platelet membranes, forming the intrinsic tenase complex with activated factor IX (FIXa). Previous studies have identified the C1 and C2 domains as the membrane binding domains of FVIII through conserved arginine residues. A membrane binding model for the FVIII C domains proposes that surface exposed hydrophobic and positively charged residues at each C domain interact with the membrane, yet a comprehensive thermodynamic and structural description of this interaction is lacking.

Objective: To determine residues of interaction, thermodynamics, and membrane binding preference for FVIII membrane association.

Methods: Binding of FVIII constructs to lipid nanodiscs were characterized with nuclear magnetic resonance (NMR), isothermal titration calorimetry (ITC), bio-layer interferometry (BLI), and X-ray crystallography.

Results: The thermodynamics of FVIII membrane binding indicate that the C1 domain associates through an enthalpically driven process while the C2 domain is entropically driven. Alanine mutations to surface-exposed hydrophobic residues in the C2 domain reveal differential effects on membrane binding, highlighting important determinants at the residue-level. The structure of a C2 double mutant, L2251A/L2252A, demonstrates that its decreased affinity is likely due to decreasing the surface area hydrophobicity. NMR studies with the C2 domain identified residues of interaction with soluble O-phospho-L-serine (OPLS) as well as lipid nanodiscs. Lastly, increasing phosphatidylethanolamine (PE) and decreasing PS content decreases overall FVIII affinity for membrane surfaces.

Conclusion: This study provides further insight into the molecular basis for how FVIII interacts with platelets to form the intrinsic tenase complex.

Background: Catheter-related thrombosis (CRT) is a complication of central venous access devices (CVADs). Evidence is variable regarding the significance of the side of catheter insertion. The role of the patient's hand dominance in predisposition to CRT remains uncertain.

Objectives: In a prospective randomised controlled trial, adult cancer patients were randomly allocated to either dominant or non-dominant side CVAD insertion. The primary endpoint of this trial examined the incidence of catheter-associated blood stream infection. Here, we report the secondary endpoint of the incidence of CRT.

Methods: 640 CVADs were randomised to the dominant (n=322) or non-dominant (n=318) side of insertion. Only symptomatic patients underwent ultrasound imaging to evaluate for CRT.

Results: The median patient age was 58, 60% of patients had haematological malignancies and 40% had solid tumours. CVADs used were peripherally-inserted central catheter line (PICC)(67%), tunnelled CVAD (23%) or non-tunnelled CVAD (10%). The CRT incidence rate was 0.65 vs 0.82 per 1000 line days in the dominant vs non-dominant group (HR 1.2; 95% CI 0.58-2.48, P=0.63). There was no significant difference in CRT incidence rate between left and right sided insertions (HR 0.63; 95% CI 0.30-1.32, P=0.22). The CRT incidence rate was lower in right-handed versus left-handed line inserters (HR 0.29; 95% CI 0.12-0.71, P=0.007).

Conclusions: The rate of CRT was not associated with whether CVAD insertion was on the patient's dominant or non-dominant side or the side of insertion. The role of inserter hand dominance requires further investigation.

Background: While the number of models for predicting the risk of cancer-associated thrombosis has been rising, there is still a lack of comprehensive assessment for machine learning prediction models.

Objective: To critically appraise and quantify the performance studies using machine learning to predict cancer-associated thrombosis.

Methods: We conducted searches on PubMed, Embase, The Cochrane Library, Cumulative Index to Nursing and Allied Health Literature, and other related databases for the related publications (from inception to December 1, 2023). The Prediction Model Risk of Bias Assessment Tool checklist was employed to evaluate the risk of bias and applicability. The Grading of Recommendations Assessment, Development and Evaluation system was used to evaluate the quality of evidence in systematic reviews. Meta-analyses were conducted using R (version 4.3.2).

Results: A total of thirty-two studies were included. Mostly included literature exhibits a high risk of bias, and the applicability of the prediction models is deemed acceptable. The twenty-one included studies in the meta-analysis demonstrated the high predictive capacity of the machine learning models for cancer-associated thrombosis.

Conclusion: Most of the prediction models included in the study showed good applicability and excellent prediction performance, but there was a high risk of bias.

Background: Aplastic anemia (AA) is a bone marrow failure disease for which the means of assessing and predicting the therapeutic effectiveness are still relatively limited. Thrombocytopenia is often the earliest and most severe symptom in patients newly diagnosed with AA (Dx-AA). While clinical consideration is usually given to the quantitative changes in platelets during treatment, there is little focus on the resolution of the molecular characteristics of platelets in AA.

Objectives: To investigate the changes in platelet molecular characteristics throughout the treatment process of AA, and to explore the use of transcriptomics for monitoring and predicting treatment outcomes.

Methods: We comprehensively analyzed platelet transcriptomic changes in AA patients at initial diagnosis and different stages of treatment effectiveness using bulk transcriptome sequencing.

Results: Genes associated with cell proliferation, erythroid function, and amino acid transport were elevated in Dx-AA. Conversely, genes linked to histones, thrombosis, mitochondrial energy metabolism, and signaling pathways were significantly downregulated. 60.6% of the differentially expressed genes were substantially restored following complete remission. Furthermore, through the examination of longitudinal samples, we identified recovery ascending genes (RAG) that could serve as viable biomarkers for assessing treatment effectiveness in AA. Besides, we observed that higher expression levels of RAG may predict superior long-term platelet counts recovery six months in advance in patients with partial response.

Conclusions: The platelet transcriptome undergoes profound changes and can serve as a potential indicator for assessing treatment effectiveness and predicting long-term platelet counts recovery in AA.

Background: Tissue factor pathway inhibitor (TFPI) is an anticoagulant protein that inhibits FXa, the TF-FVIIa-FXa complex, and early forms of the prothrombinase complex. Concizumab is a monoclonal antibody that blocks FXa inhibition by TFPI and reduces bleeding in hemophilia.

Objectives: To examine how concizumab impacts various reactions of TFPI to restore thrombin generation in hemophilia A using mathematical models.

Methods: A compartment model was used to estimate plasma concentrations of free concizumab and its complexes with TFPIα and TFPIβ. Concizumab was integrated into a flow-mediated mathematical model of coagulation and a small injury was simulated under hemophilia A conditions. Simulations were then analyzed to determine how concizumab's blockade of TFPI anticoagulant activities, specifically the inhibition of FXa in plasma and on platelets, inhibition of TF:VIIa at the subendothelium, and prior sequestration of plasma TFPIα to the endothelium via TFPIβ, altered thrombin generation.

Results: Concizumab improved simulated thrombin generation in hemophilia A by simultaneously altering all three mechanisms of TFPI anticoagulant blockade examined. Concizumab sequesters ∼75% of plasma TFPIα through formation of ternary TFPIα-concizumab-TFPIβ-complexes. For all TF levels, reducing the TFPIα plasma concentration had the largest impact on the lag time followed by blocking TFPIα inhibition of TF:VIIa:FXa and subsequently followed by blocking TFPIα inhibition of FXa in plasma and on the platelet surface.

Conclusions: The effectiveness of concizumab is mediated through blockade of TFPI anticoagulant activities in plasma and on multiple physiological surfaces. An important and previously unrecognized function of concizumab was sequestration of plasma TFPIα to the endothelium.

Background: Understanding of the hemostatic and complement alterations associated with cardiopulmonary bypass (CPB) in pediatric patients and the impact of these alterations on outcome is limited.

Objectives: The present study prospectively characterized these alterations and their association with postoperative outcomes in pediatric CPB.

Patients/methods: All patients <21 years undergoing CPB at the authors' institution between 2020 and 2021 that weighed >3 kg, were >36 weeks gestational age, and had no known prothrombotic or hemorrhagic disorders were eligible. Blood samples were analyzed for multiple hemostatic and complement biomarkers pre-, intra-, and 24 hours post-CPB. Biomarker levels were compared to clinical outcomes, including chest tube output (CTO).

Results: Fifty consecutive patients were enrolled. CPB resulted in multiple significant alterations in hemostatic and complement components. Lower platelet counts (<80 x 10⁹ platelets/L) at CPB termination were associated with increased postoperative CTO (p=0.003). Lower factor VIII levels (<60 IU/dl) at the end of CPB were associated with a longer hospital stay (p<0.001) and increased postoperative CTO (p<0.001). Patients undergoing staged single ventricle reconstruction were more likely to have lower platelet counts at CPB termination (p=0.009) and higher CTO postoperatively (p=0.001) than patients undergoing other types of surgical repair. These differences were not due to different preoperative platelet counts, increased incidences of circulatory arrest, or longer CPB times.

Conclusions: These data suggest that intraoperative alterations in hemostatic system components may predict postoperative outcomes in pediatric CPB. Further study is needed to determine if interventions targeting platelets or factor VIII could improve outcomes in pediatric CPB.

Acquired Hemophilia A (AHA) is a rare bleeding disorder caused by inhibitory autoantibodies to factor VIII (FVIII). The goals of treatment are two-fold, namely immunosuppressive therapy (IST) to eradicate the inhibitor and hemostatic management to control bleeding. Emicizumab, a bispecific antibody that acts as a factor VIIIa (FVIIIa) mimetic, has seen growing use in AHA following its approval for congenital hemophilia A (cHA). This review provides an overview of the epidemiology, pathophysiology, diagnosis, and treatment of AHA. Registry, trial, and case series data are assimilated and summarized with an emphasis on a standardized approach that integrates the use of emicizumab. With recent registry data suggesting the need to focus on immunosuppression-related mortality in AHA, we provide treatment recommendations in an algorithmic format that have become the standard of care at our institution. These recommendations are intended to minimize hemostatic product usage and potential toxicity related to IST, while reducing morbidity and re-hospitalization rates for bleeding. The proposed treatment algorithm, which includes key interventions by phase of therapy, can be readily implemented at centers that have rapid access to plasma FVIII activity using a one-stage assay. A case is presented to illustrate the proposed diagnostic and management considerations.