FVIII/VWF complex displays a greater pro-haemostatic activity than FVIII preparations devoid of VWF: Study in plasma and cell-based models.

INTRODUCTION: Plasma-derived FVIII/VWF complex was reported to be less sensitive to inhibitors than FVIII preparations devoid of VWF. AIM: To compare the efficacy of FVIII/VWF complex (Fanhdi) and five different VWF-free FVIII preparations in restoring thrombin generation and activation of thrombin-activatable fibrinolysis inhibitor (TAFI) in haemophilic plasma, with and without inhibitor, and in cell-based models. METHODS: Experiments were performed in haemophilic plasma supplemented with inhibitory IgG or in plasma samples obtained from haemophilia A patients without (n = 11) and with inhibitor (n = 12). Thrombin generation was evaluated by calibrated automated thrombography (CAT) under standard conditions, in the presence of activated protein C (APC) or thrombomodulin (TM), and in cell-based models including endothelial cells, either alone or in combination with platelets or tissue factor-expressing blood mononuclear cells. The kinetics of TAFI activation was determined by a two-stage functional assay in the absence and in the presence of APC. RESULTS: In haemophilic plasma without inhibitor, Fanhdi enhanced thrombin generation and TAFI activation as well as recombinant (2nd-4th generation) and plasma-derived FVIII preparations devoid of VWF. On the contrary, in plasma with inhibitor, Fanhdi displayed a greater ability to restore thrombin generation and TAFI activation under all tested conditions. Notably, in cell-based models including endothelial cells, Fanhdi proved more efficient than all other preparations in improving thrombin generation even in the absence of inhibitor. CONCLUSION: The greater pro-haemostatic activity of FVIII/VWF complex, either in haemophilic plasma with inhibitor or in the presence of endothelial cells, may offer therapeutic advantages.

Inflammation as Prognostic Hallmark of Clinical Outcome in Patients with SARS-CoV-2 Infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is often characterized by a life-threatening interstitial pneumonia requiring hospitalization. The aim of this retrospective cohort study is to identify hallmarks of in-hospital mortality in patients affected by Coronavirus Disease 19 (COVID-19). A total of 150 patients admitted for COVID-19 from March to June 2021 to "F. Perinei" Murgia Hospital in Altamura, Italy, were divided into survivors (n = 100) and non-survivors groups (n = 50). Blood counts, inflammation-related biomarkers and lymphocyte subsets were analyzed into two groups in the first 24 h after admission and compared by Student's t-test. A multivariable logistic analysis was performed to identify independent risk factors associated with in-hospital mortality. Total lymphocyte count and CD3+ and CD4+ CD8+ T lymphocyte subsets were significantly lower in non-survivors. Serum levels of interleukin-6 (IL-6), lactate dehydrogenase (LDH), C-reactive protein (CRP) and procalcitonin (PCT) were significantly higher in non-survivors. Age > 65 years and presence of comorbidities were identified as independent risk factors associated with in-hospital mortality, while IL-6 and LDH showed a borderline significance. According to our results, markers of inflammation and lymphocytopenia predict in-hospital mortality in COVID-19.

Differential effect of direct oral anticoagulants on thrombin generation and fibrinolysis in patients with atrial fibrillation and venous thromboembolism.

BACKGROUND: Recent reports suggest that direct oral anticoagulants (DOAC) may induce different anticoagulant and profibrinolytic responses. We performed a head-to-head comparison of the changes in thrombin generation (TG) parameters and tissue plasminogen activator (t-PA)-induced clot lysis produced by different DOAC. MATERIAL AND METHODS: We tested 137 plasma samples from patients with non-valvular atrial fibrillation (n=72) and venous thromboembolism (n=65) under treatment with apixaban (n=38), edoxaban (n=29), rivaroxaban (n=39), or dabigatran (n=31). TG was evaluated by a fluorometric assay and fibrinolysis by measuring the lysis time of clots exposed to 40 ng/mL t-PA. RESULTS: Trough-to-peak changes of TG parameters, along with correlation analysis, showed that all DOAC prolonged the lag-time in a concentration-dependent fashion. As for the other parameters, anti-factor Xa drugs markedly reduced the thrombin peak and velocity index but had little (rivaroxaban) or no effect on endogenous thrombin potential (ETP); dabigatran, instead, reduced ETP, weakly decreased thrombin peak and did not influence the velocity index, as also inferred from the changes in TG values after neutralisation of dabigatran with idarucizumab. Concerning the profibrinolytic effect of DOAC, intergroup comparison showed that the clot lysis time of dabigatran samples was significantly shorter than that of the apixaban and rivaroxaban samples, at both C-Trough and C-Peak. Moreover, a significant correlation between trough-to-peak changes in drug level and clot lysis time was only observed in the dabigatran group (rho=0.53). Finally, after DOAC removal by DOAC-stop, only dabigatran samples showed a significant increase in lysis time. DISCUSSION: Our data show that dabigatran inhibits TG in a different way than anti-Xa DOAC; moreover, under our conditions, only dabigatran displayed profibrinolytic activity, most likely because of its distinctive effect on the TG curve.

Thrombin activatable fibrinolysis inhibitor pathway alterations correlate with bleeding phenotype in patients with severe hemophilia A.

BACKGROUND: Patients with severe hemophilia A display varied bleeding phenotypes despite similar factor VIII (FVIII) activity levels. OBJECTIVE: We investigated different thrombin activatable fibrinolysis inhibitor (TAFI)-related variables in patients with severe hemophilia A and their possible correlation with bleeding tendency. PATIENTS/METHODS: Sixty-one patients with severe hemophilia A (FVIII:C <1%], treated on demand, were included. Patients were categorized as mild, moderate, and severe bleeders according to number of bleeds per year (≤2, 3-24, ≥25, respectively). Thirty healthy males served as controls. Clot lysis time was assessed by turbidimetric assay, TAFI activation by two-stage functional assay, and response to TAFIa as the prolongation of fibrinolysis time upon addition of purified TAFIa. Circulating levels of activated TAFI (TAFIa/ai) were measured by specific enzyme-linked immunosorbent assay. RESULTS: As compared to controls, hemophilic patients displayed shorter lysis time, less TAFIa generation, and reduced response to TAFIa, but similar TAFIa/ai levels. Clot lysis time was similar in mild, moderate, and severe bleeders, whereas TAFIa generation and response to TAFIa decreased with the increase in bleeding tendency; moreover, circulating TAFIa/ai levels were highest in severe bleeders. Patients with markedly impaired TAFIa generation or TAFIa response (below median) displayed 3-fold to 4-fold higher bleeding rate and factor consumption than patients whose TAFI-related values approached the control ones. CONCLUSION: The TAFI pathway impairment correlates with bleeding phenotype in severe hemophilia and may represent a promising tool to stratify the bleeding risk.