Background:Antithrombin, PC (protein C), and PS (protein S) are circulating natural anticoagulant proteins that regulate hemostasis and of which partial deficiencies are causes of venous... Show moreBackground:Antithrombin, PC (protein C), and PS (protein S) are circulating natural anticoagulant proteins that regulate hemostasis and of which partial deficiencies are causes of venous thromboembolism. Previous genetic association studies involving antithrombin, PC, and PS were limited by modest sample sizes or by being restricted to candidate genes. In the setting of the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium, we meta-analyzed across ancestries the results from 10 genome-wide association studies of plasma levels of antithrombin, PC, PS free, and PS total. Methods:Study participants were of European and African ancestries, and genotype data were imputed to TOPMed, a dense multiancestry reference panel. Each of the 10 studies conducted a genome-wide association studies for each phenotype and summary results were meta-analyzed, stratified by ancestry. Analysis of antithrombin included 25 243 European ancestry and 2688 African ancestry participants, PC analysis included 16 597 European ancestry and 2688 African ancestry participants, PSF and PST analysis included 4113 and 6409 European ancestry participants. We also conducted transcriptome-wide association analyses and multiphenotype analysis to discover additional associations. Novel genome-wide association studies and transcriptome-wide association analyses findings were validated by in vitro functional experiments. Mendelian randomization was performed to assess the causal relationship between these proteins and cardiovascular outcomes. Results:Genome-wide association studies meta-analyses identified 4 newly associated loci: 3 with antithrombin levels (GCKR, BAZ1B, and HP-TXNL4B) and 1 with PS levels (ORM1-ORM2). transcriptome-wide association analyses identified 3 newly associated genes: 1 with antithrombin level (FCGRT), 1 with PC (GOLM2), and 1 with PS (MYL7). In addition, we replicated 7 independent loci reported in previous studies. Functional experiments provided evidence for the involvement of GCKR, SNX17, and HP genes in antithrombin regulation. Conclusions:The use of larger sample sizes, diverse populations, and a denser imputation reference panel allowed the detection of 7 novel genomic loci associated with plasma antithrombin, PC, and PS levels. Show less
Sedek, L.; Flores-Montero, J.; Sluijs, A. van der; Kulis, J.; Marvelde, J. te; Philippe, J.; ... ; Orfao, A. 2022
Simple Summary Objective: interpretation of flow cytometry may be hampered by a lack of standardized sample preparation procedures. The EuroFlow consortium conducted a series of experiments to... Show moreSimple Summary Objective: interpretation of flow cytometry may be hampered by a lack of standardized sample preparation procedures. The EuroFlow consortium conducted a series of experiments to determine the potential impact of different pre-analytical and analytical factors on the variability of results in terms of relative cell populations distribution and marker expression levels. The experiments were performed on healthy donors and patients with different hematological malignancies (e.g., acute leukemia, lymphoma, multiple myeloma, and myelodysplastic syndrome) to mimic real-world clinical settings. Overall, the results showed that sample storage conditions, anticoagulant use, and sample processing protocol might need to be tailored for sample and cell type(s), as well as to the specific markers evaluated. However, defining of well-balanced boundaries for storage time to 24 h, staining-acquisition delay to 3 h, and choosing a washing buffer of pH within the range of 7.2 to 7.8 would be a valid recommendation for most applications and circumstances described herein. Objective: interpretation of FC results may still be hampered by limited technical standardization. The EuroFlow consortium conducted a series of experiments to determine the impact of different variables on the relative distribution and the median fluorescence intensity (MFI) of markers stained on different cell populations, from both healthy donors and patients' samples with distinct hematological malignancies. The use of different anticoagulants; the time interval between sample collection, preparation, and acquisition; pH of washing buffers; and the use of cell surface membrane-only (SM) vs. cell surface plus intracytoplasmic (SM+CY) staining protocols, were evaluated. Our results showed that only monocytes were represented at higher percentages in EDTA- vs. heparin-anticoagulated samples. Application of SM or SM+CY protocols resulted in slight differences in the percentage of neutrophils and debris determined only with particular antibody combinations. In turn, storage of samples for 24 h at RT was associated with greater percentage of debris and cell doublets when the plasma cell disorder panel was used. Furthermore, 24 h storage of stained cells at RT was selectively detrimental for MFI levels of CD19 and CD45 on mature B- and T-cells (but not on leukemic blasts, clonal B- and plasma cells, neutrophils, and NK cells). The obtained results showed that the variables evaluated might need to be tailored for sample and cell type(s) as well as to the specific markers compared; however, defining of well-balanced boundaries for storage time, staining-to-acquisition delay, and pH of washing buffer would be a valid recommendation for most applications and circumstances described herein. Show less
Although direct-acting oral anticoagulants (DOACs) have widespread first-line use for treatment and prevention of venous thromboembolism (VTE), uncertainty remains regarding their efficacy and... Show moreAlthough direct-acting oral anticoagulants (DOACs) have widespread first-line use for treatment and prevention of venous thromboembolism (VTE), uncertainty remains regarding their efficacy and safety in patients with obesity. We reviewed available data for use of DOACs for VTE treatment and prevention in patients with obesity, including phase 3, phase 4, meta-analyses, and pharmacokinetic and pharmacodynamics studies. In addition, we reviewed available data regarding DOACs in bariatric surgery. We provide updated guidance recommendations on using DOACs in patients with obesity for treatment and prevention of VTE, as well as following bariatric surgery. Show less
Maag, A.; Sharma, P.; Schuijt, T.J.; Kopatz, W.F.; Kruijswijk, D.; Marquart, J.A.; ... ; Veer, C. van 't 2021
Background The prothrombinase complex consists of factors Xa (FXa) and Va (FVa) on an anionic phospholipid surface and converts prothrombin into thrombin. Both coagulation factors require... Show moreBackground The prothrombinase complex consists of factors Xa (FXa) and Va (FVa) on an anionic phospholipid surface and converts prothrombin into thrombin. Both coagulation factors require activation before complex assembly. We recently identified TIX-5, a unique anticoagulant tick protein that specifically inhibits FXa-mediated activation of FV. Because TIX-5 inhibited thrombin generation in blood plasma, it was concluded that FV activation by FXa contributes importantly to coagulation.Objective We aimed to unravel the structure-function relationships of TIX-5.Method We used a structure model generated based on homology with the allergen Der F7.Results Tick inhibitor of factor Xa toward FV was predicted to consist of a single rod formed by several beta sheets wrapped around a central C-terminal alpha helix. By mutagenesis we could show that two hydrophobic loops at one end of the rod mediate the phospholipid binding of TIX-5. On the other end of the rod an FV interaction region was identified on one side, whereas on the other side an EGK sequence was identified that could potentially form a pseudosubstrate of FXa. All three interaction sites were important for the anticoagulant properties of TIX-5 in a tissue factor-initiated thrombin generation assay as well as in the inhibition of FV activation by FXa in a purified system.Conclusion The structure-function properties of TIX-5 are in perfect agreement with a protein that inhibits the FXa-mediated activation on a phospholipid surface. The present elucidation of the mechanism of action of TIX-5 will aid in deciphering the processes involved in the initiation phase of blood coagulation. Show less
Ageno, W.; Vedovati, M.C.; Cohen, A.; Huisman, M.; Bauersachs, R.; Gussoni, G.; ... ; Agnelli, G. 2020
Background Direct oral anticoagulants are recommended for the treatment of cancer-associated thrombosis (CAT) as an alternative to low-molecular-weight heparin (LMWH), but an increased bleeding... Show moreBackground Direct oral anticoagulants are recommended for the treatment of cancer-associated thrombosis (CAT) as an alternative to low-molecular-weight heparin (LMWH), but an increased bleeding risk in patients with gastrointestinal cancer was reported. The Caravaggio study compared apixaban and dalteparin for the treatment of patients with CAT. Here we describe sites of bleeding, associated cancer sites, clinical presentation, and course of major bleeding in patients included in the Caravaggio study.Methods The Caravaggio study was a multinational, randomized, open-label, noninferiority study. Bleeding events and the severity of major bleedings were adjudicated by a committee unaware of treatment allocation using predefined criteria; for the purpose of this analysis, data were analyzed in the safety population.Results Major bleeding occurred in 22 of 576 patients on apixaban (3.8%) and in 23 of 579 patients on dalteparin (4.0%). The sites of major bleeding and their distribution according to the type of cancer were similar between the two treatment groups. Major bleeding occurred in nine patients with gastrointestinal cancer in each treatment group. The clinical presentation of major bleeding was severe or fatal in 6 patients on apixaban and in 5 patients on dalteparin, while the clinical course was severe in 5 patients on apixaban and in 7 patients on dalteparin.Conclusion Apixaban is a safe alternative to LMWH for the treatment in patients with CAT. No excess in gastrointestinal bleeding was observed in patients who received apixaban, including those with gastrointestinal cancer. Show less
