Journal of Thrombosis and Haemostasis最新文献

Introduction: The pediatric direct oral anticoagulation (DOAC) trials provide an opportunity to evaluate and characterize challenges in their design and execution to inform future antithrombotic trials.

Objective: To perform a systematic review of pediatric DOAC trials for the treatment of venous thromboembolism to critically appraise their methodology and understand the feasibility and challenges.

Methods: Systematic search of MEDLINE, EMBASE, the Cochrane Library and ClinicalTrials.gov (January 2002 to December 2022). Studies reporting the results of interventional trials of a DOAC for the treatment of acute VTE in children, and their respective design papers were included. Trial registration information was reviewed in clinicaltrials.gov. Discrepancies in study design, targeted populations, sample size and analyses between planned and actual trial conduct were examined qualitatively.

Results: Five published studies, and unpublished data for two additional trials were included. All trials had modifications to their design or methodology, and discrepancies between the trial's registration and the final published study, suggesting feasibility challenges. Modifications to the eligibility criteria, changes in sample size, challenges with recruitment of younger patients, and enrolled population not matching the clinical target population were identified for all trials. Discrepancies in outcome reporting, particularly for secondary endpoints, were also common.

Conclusions: DOAC trials experienced feasibility challenges that led to design or methodology modifications. Future pediatric antithrombotic trials will need to be adaptive in their design, prioritize enrollment of younger children and input from clinicians providing care to target populations, ensure that enrolled populations match the clinical population, and select clinically meaningful endpoints.

Background: There are limited data regarding the association between cancer and ischemic stroke, particularly among individuals with previous stroke. Our objective was to measure and compare the risk of ischemic stroke in individuals with and without cancer.

Methods: Population-based matched cohort study in Ontario, Canada. Participants ≥18 years with a new diagnosis of cancer were matched (1:1) to cancer-free controls by age and sex in two separate matched cohorts based on the absence (Matched Cohort 1) or presence (Matched Cohort 2) of prior ischemic stroke. The primary outcome was the incidence of ischemic stroke. We calculated sub-distribution adjusted hazard ratios (aHR) and 95% confidence intervals (CI) for ischemic stroke (death as a competing event).

Results: In Matched Cohort 1, the rate and risk of ischemic stroke were higher among 620,647 cancer patients versus 620,647 controls at 1.5 years (4.6/1000 person-years [95%CI 4.5-4.7] vs 3.5/1000 person-years [95%CI 3.4-3.6], aHR 1.40, 95%CI 1.34-1.47). In Matched Cohort 2, the rate and risk of ischemic stroke were similar among 13,924 cancer patients and 13,924 controls at 1.5 years (26.9/1000 person-years [95%CI 25.1-28.9] vs 22.0 /1000 person-years [95/%CI 20.7-23.4]; aHR 1.00, 95%CI 0.88-1.14). In both cohorts, the risk of ischemic stroke was lower in cancer patients versus controls from 1.5 to 5 years (aHR 0.72, 95%CI 0.69-0.74 and aHR 0.53, 95%CI 0.46-0.62).

Conclusions: Compared to cancer-free controls, the rate and risk of ischemic stroke were higher 1.5 years after cancer diagnosis in individuals without prior stroke and varied according to cancer site and stage.

Background: Portal vein thrombosis (PVT) is a common complication in patients with end-stage liver disease (ESLD). The portal vein in ESLD patients is proposedly an inflammatory vascular bed due to translocation of endotoxins and cytokines from the gut. We hypothesized that a pro-inflammatory gut microbiome and elevated trimethylamine N-oxide (TMAO), a driver of thrombosis, may contribute to PVT development.

Objectives: We investigated whether gut microbiome diversity, bacterial species, metabolic pathways, and TMAO levels are associated with PVT in ESLD patients.

Methods: Fecal samples, plasma samples and data from ESLD patients and healthy controls were collected through the TransplantLines Biobank and Cohort Study. PVT was defined as a thrombus in the portal vein within a year prior to or after fecal sample collection. Fecal samples were analyzed using Shotgun Metagenomic Sequencing, and TMAO levels were measured in plasma using a Vantera® Clinical Analyzer.

Results: 102 ESLD patients, of which 23 with PVT, and 246 healthy controls were included. No significant difference in gut microbiome diversity was found between patients with PVT and without PVT (P=0.18). Both ESLD groups had significantly lower alpha-diversity compared with controls. Bacteroides fragilis and three Clostridiales species were increased in patients with PVT compared to without PVT. TMAO levels between the three groups were not significantly different.

Conclusion: We observed profound differences in gut microbiota between ESLD patients and controls, but minimal differences between ESLD patients with or without PVT. In our cohort, a gut-derived pro-inflammatory state was not associated with presence of PVT in ESLD patients.

Background: Thrombin prefers substrates carrying Arg at the site of cleavage (P1) because of the presence of D189 in the primary specificity (S1) pocket but can also cleave substrates carrying Phe at P1. The structural basis of this property is unknown.

Objective: Solve the X-ray structure of thrombin bound to a ligand carrying Phe at P1 and investigate the effects of replacing D189.

Methods: X-ray crystallography is used to solve the structure of thrombin bound to the irreversible inhibitor H-D-Phe-Pro-Phe-CH₂Cl (PPPCK). Residue D189 is mutated to Ala, Lys, Phe and Ser.

Results: The X-ray structure of the thrombin-PPPCK complex is solved at 2.5 Å resolution and compared to the structure of thrombin bound to H-D-Phe-Pro-Arg-CH₂Cl (PPACK). PPPCK binds to thrombin in a conformation similar to that of PPACK, but Phe at P1 makes no contacts with D189. Replacement of D189 with Ala, Lys, Phe or Ser reverses both substrate preference and stability enhancement from Arg to Phe.

Conclusions: D189 in the S1 pocket confers thrombin "trypsin-like" specificity for Arg at P1. However, the S1 pocket is wide enough to also enable "chymotrypsin-like" specificity for Phe at P1. Consistent with these structural features, a single amino acid replacement (D189A) switches thrombin specificity from trypsin-like to chymotrypsin-like, converting the substrate preference from H-D-Phe-Pro-Arg-p-nitroanilide to H-D-Phe-Pro-Phe-p-nitroanilide and preferential stability enhancement from PPACK to PPPCK. The observation that thrombin specificity is controlled mainly by a single residue establishes a new paradigm in the field of trypsin-like proteases.

Background: Immune thrombocytopenia (ITP) is characterized by immune-mediated platelet destruction and impaired megakaryocyte maturation. Hypoxia-inducible factor-1 alpha (HIF-1α), pivotal in the development of megakaryocytes and immune regulation, is downregulated in ITP. Roxadustat, which stabilizes HIF-1α, has emerged as a potential therapeutic drug for ITP that acts by enhancing HIF-1α-mediated megakaryocyte development and modulating immune responses.

Objectives: This study evaluates the safety profile of roxadustat and its therapeutic efficacy for ITP treatment using Mendelian randomization (MR) analysis.

Methods: We used expression Quantitative Trait Loci (eQTLs) data for roxadustat's target genes (EGLN1, EGLN2, EGLN3) and genetic associations with ITP, and adverse outcomes from the Open Genome-Wide Association Study (OpenGWAS) project. MR analysis included IVW, MR-Egger regression, weighted median, and MR pleiotropy residual sum and outlier (MR-PRESSO) methods to evaluate pleiotropy. Heterogeneity was assessed using Cochran's Q statistic and I² measure, with sensitivity analyses. A meta-analysis was performed to integrate effect sizes from multiple literature sources.

Results: MR analysis revealed a significant association between roxadustat and reduced ITP risk (odds ratio [OR] 0.79, 95% confidence interval [CI] 0.66-0.95, P=0.01) with no evidence of horizontal pleiotropy. Meta-analysis confirmed the protective effect of roxadustat on ITP. Utilizing eQTLs of roxadustat's target gene EGLN1 as instrumental variables, an MR analysis of 39 potential adverse reactions revealed no significant increase, suggesting a favorable safety profile for roxadustat.

Conclusion: Roxadustat demonstrates a potential protective effect against ITP without increasing the risk of adverse outcomes, suggesting its promise as a therapeutic option for ITP and warranting further investigation.

Background: Genetically determined amino acid substitutions in the platelet adhesive A1 domain alter von Willebrand factor's platelet agglutination competence resulting in both gain- (Type 2B) and loss-of-function (Type 2M) phenotypes of Von Willebrand disease. Prior studies of variants in both phenotypes revealed defects in secondary structure that altered stability and folding of the domain. An intriguing observation was that loss of function arose from both misfolding of A1 and, in a few cases, hyper-stabilization of the native structure.

Objectives: To fully understand the 2M phenotype, we thoroughly investigated the structure/function relationships of fifteen additional type 2M variants and two polymorphisms in the A1 domain.

Methods: These variants were characterized using circular dichroism, fluorescence, calorimetry, hydrogen deuterium exchange mass spectrometry, surface plasmon resonance, and platelet adhesion under shear flow.

Results: Six variants were natively folded with four being hyper-stabilized. Nine variants disordered A1, causing a loss in α-helical structure and unfolding enthalpy. GPIbα binding affinity and platelet adhesion dynamics were highly correlated to helical structure. Hydrogen deuterium exchange resolved specific C-terminal secondary structure elements that differentially diminish the GPIbα binding affinity of A1. These localized structural perturbations were highly correlated to GPIbα binding affinity and shear-dependent platelet adhesion.

Conclusions: While hyper-stabilized dynamics in A1 do impair stable platelet attachment to VWF under flow, variant-induced localized disorder in specific regions of the domain misfolds A1 and abrogates platelet adhesion. These two opposing conformational properties represent two structural classes of VWF that drive the loss-of-function phenotype that is type 2M VWD.

Background: Immune thrombocytopenia during pregnancy (PITP) is the most common cause of platelet reduction in early and mid-pregnancy. However, the pathogenesis of PITP is still unclear.

Objectives: To determine the characteristics of bone marrow mesenchymal stem cells (BM-MSCs) in PITP patients and to explore the associations between metabolites, the gut microbiota, and BM-MSCs in PITP.

Methods: The characteristics of BM-MSCs were detected through in vitro and in vivo experiments. Non-targeted metabolomics was used to screen metabolites. The features of the gut microbiota were analyzed by 16S rDNA sequencing. PITP and a fecal microbiota transplantation (FMT) mouse model were established to explore the associations between metabolites, the gut microbiota, and BM-MSCs.

Results: BM-MSCs from PITP patients had significant senescence and apoptosis, as well as impaired immunoregulatory function. Metabolomic analysis indicated that progesterone was the most significant specific metabolite in PITP patients. In vivo studies showed that progesterone mediated the MSCs injury. Further analysis of the gut microbiota and FMT experiments revealed that progesterone mediated BM-MSCs injury by regulating the the composition of the gut microbiota in the PITP. RNA-seq analysis of BM-MSCs from FMT mice revealed abnormal expression of genes related to cell aging and the NOD-like receptor signaling pathway.

Conclusion: In conclusion, BM-MSCs in the PITP were significantly impaired, which was associated with increased progesterone and changes in the gut microbiota regulated by progesterone. Intervening with the gut microbiota may become a new treatment for PITP.

Background: Blood clot formation, triggered by vascular injury, is crucial for haemostasis and thrombosis. Blood clots are composed mainly of fibrin fibres, platelets and red blood cells (RBCs). Recent studies show that clot surface also develops a fibrin film, which provides protection against wound infection and retains components such as RBCs within the clot. However, the role of fibrin films in thrombi remains poorly understood.

Objectives: Explore the relationship between fibrin films and inflammation, RBC concentration, platelets and fibrinolysis activity.

Patients/methods: We used laser scanning confocal and scanning electron microscopy, ELISA, turbidity and fibrinolysis assays to investigate the interactions between fibrin film and inflamed endothelium, RBCs, platelets and fibrinolysis.

Results: We found that plasma clots forming on top of inflamed endothelial cells show less fibrin film coverage and are characterized by higher fiber density and shorter lag time compared to control cells. Blood clots formed under conditions of high haematocrit showed significantly more fibrin film coverage than low haematocrit clots. We found that platelet adhesion was significantly reduced on clots with film compared with clots without film even when platelets were preactivated. Fibrinolysis was faster in clots without film than in clots with film, partly due to reductions in plasmin generation.

Conclusions: Our findings indicate that reductions in fibrin film formation under thromboinflammatory conditions support continued clot growth, through effects on increased platelet adhesion and activation. On the other hand, increased fibrin film impairs fibrinolysis. These data show a multifaceted role of the fibrin film in clot growth and stability.

Background: Postthrombotic syndrome (PTS) is a chronic condition following deep vein thrombosis (DVT) and is associated with pain, swelling, and restricted use of the affected limb. In pediatric age groups, its incidence and risk factors are not well-known.

Methods: This observational cohort study of all consecutive children (≤18 years) with DVT treated at the Emma Children's Hospital Amsterdam between January 2001 and January 2021 was conducted to identify incidence and risk factors for PTS in neonates aged ≤2 months and children aged >2 months. PTS was diagnosed using the modified Villalta scale.

Results: In total, 315 patients were included. The 20-year incidence of PTS was 20.0% in neonates and 40.0% in children. In neonates, involvement of ≥3 vessels (odds ratio [OR], 6.6; 95% CI, 1.6-26.4) and incomplete thrombus resolution (OR, 3.0; 95% CI, 1.1-8.0) were risk factors for PTS. In children, involvement of ≥3 vessels (OR, 6.2; 95% CI, 2.2-17.8), recurrent DVT (OR, 3.7; 95% CI, 1.3-10.3), and incomplete thrombus resolution (OR, 5.2; 95% CI, 1.6-17.0) were associated with PTS. Exercise ≥3 times/wk (OR, 0.4; 95% CI, 0.2-0.9), central venous catheter-related DVT (OR, 0.2; 95% CI, 0.1-0.5), and provoked DVT (OR, 0.4; 95% CI, 0.1-0.97) were protective factors for PTS.

Conclusion: This study demonstrated a high incidence of pediatric PTS. Additionally, risk factors for PTS differed between neonates and children. These findings provide a basis for better prevention and management of PTS that may differ between neonates and children.

Background: Same-day emergency care (SDEC) is an expanding area of hospital acute medical care. It aims to minimize delays and manage medical emergency patients within the same day, enabling hospitalization to be avoided; the expectation is that the patients would have required inpatient hospitalization in the absence of the SDEC service. Venous thromboembolism (VTE) prevention is a key medical inpatient safety measure. Whether VTE prevention should be considered for SDEC patients is unknown.

Objectives: To examine the incidence and predictors of VTE diagnosed within 90 days of SDEC assessment.

Methods: Data were obtained from electronic health records of people who received SDEC at our hospital during a 5-year period (April 2016 to March 2021).

Results: There were 40 045 attendance episodes by 33 715 individuals. Median age was 60 years (IQR, 41.0-76.0 years), and 55.2% were women. Three hundred forty-nine patients (0.9%) developed a VTE within 90 days of SDEC. Increased risk of VTE was associated with age more than 60 years, prior malignancy (adjusted odds ratio [OR], 4.12; 95% CI, 3.19-5.32; P < .0001), history of diseases of the circulatory system (adjusted OR, 2.92; 95% CI, 2.27-3.76; P < .0001), and having 1 or more additional SDEC attendances within 30 days (adjusted OR, 4.61; 95% CI, 3.65-5.82; P < .0001). In the 90 days prior to VTE diagnosis, 36.6% of patients had a separate inpatient admission in addition to SDEC. There was no association with completion of an electronic VTE risk assessment (adjusted OR, 0.96; 95% CI, 0.76-1.20).

Conclusion: The incidence of VTE following SDEC is similar to that reported for symptomatic VTE in traditional medical inpatients without thromboprophylaxis.