scholarly journals The Role of Factor XI in Thrombin Generation Induced by Low Concentrations of Tissue Factor

2001 ◽  
Vol 85 (06) ◽  
pp. 1060-1065 ◽  
Author(s):  
Irene Keularts ◽  
Ariella Zivelin ◽  
Uri Seligsohn ◽  
H. Coenraad Hemker ◽  
Suzette Béguin
Keyword(s):  
Tissue Factor ◽  
Thrombin Generation ◽  
Contact Activation ◽  
Factor Xi ◽  
Platelet Poor Plasma ◽  
Low Concentrations ◽  
Time Determination ◽  
Thrombin Formation

SummaryThrombin generation has been studied in the plasma of severely factor XI deficient patients under conditions in which contact activation did not play a role. In platelet-rich as well as platelet-poor plasma, thrombin generation was dependent upon the presence of factor XI at tissue factor concentrations of between 1 and 20 pg/ml i.e. ~ 0.01 to 0.20% of the concentration normally present in the thromboplastin time determination. The requirement for factor XI is low; significant thrombin generation was seen at 1% factor XI; at 10%, thrombin formation was nearly normalised. A suspension of normal platelets in severely factor XI deficient plasma did not increase thrombin generation. This implies that there is no significant factor XI activity carried by normal platelets, although the presence of factor XI and factor XI inhibitors in platelets cannot be ruled out.

scholarly journals Factor XI contributes to thrombin generation in the absence of factor XII

Blood ◽  
2009 ◽  
Vol 114 (2) ◽  
pp. 452-458 ◽  
Author(s):  
Dmitri V. Kravtsov ◽  
Anton Matafonov ◽  
Erik I. Tucker ◽  
Mao-fu Sun ◽  
Peter N. Walsh ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Thrombin Generation ◽  
Factor Xa ◽  
Factor Ix ◽  
Factor Xii ◽  
Factor Xi ◽  
Factor Xii Deficiency ◽  
Low Concentrations

Abstract During surface-initiated blood coagulation in vitro, activated factor XII (fXIIa) converts factor XI (fXI) to fXIa. Whereas fXI deficiency is associated with a hemorrhagic disorder, factor XII deficiency is not, suggesting that fXI can be activated by other mechanisms in vivo. Thrombin activates fXI, and several studies suggest that fXI promotes coagulation independent of fXII. However, a recent study failed to find evidence for fXII-independent activation of fXI in plasma. Using plasma in which fXII is either inhibited or absent, we show that fXI contributes to plasma thrombin generation when coagulation is initiated with low concentrations of tissue factor, factor Xa, or α-thrombin. The results could not be accounted for by fXIa contamination of the plasma systems. Replacing fXI with recombinant fXI that activates factor IX poorly, or fXI that is activated poorly by thrombin, reduced thrombin generation. An antibody that blocks fXIa activation of factor IX reduced thrombin generation; however, an antibody that specifically interferes with fXI activation by fXIIa did not. The results support a model in which fXI is activated by thrombin or another protease generated early in coagulation, with the resulting fXIa contributing to sustained thrombin generation through activation of factor IX.

scholarly journals The Effect of Trace Amounts of Tissue Factor on Thrombin Generation in Platelet Rich Plasma, its Inhibition by Heparin

1989 ◽  
Vol 61 (01) ◽  
pp. 025-029 ◽  
Author(s):  
S Béguin ◽  
T Lindhout ◽  
H C Hemker
Keyword(s):  
Synergistic Effect ◽  
Human Brain ◽  
Tissue Factor ◽  
Thrombin Generation ◽  
Platelet Rich Plasma ◽  
Blood Platelets ◽  
Thrombin Inhibitor ◽  
Platelet Poor Plasma ◽  
Activated Platelets ◽  
Low Concentrations

SummaryAmounts of human brain thromboplastin that do not stimulate thrombin generation in platelet poor plasma, were shown to advance by about 4 min an explosive formation of thrombin that occurs after recalcification in the presence of blood platelets. This synergistic effect is inhibited by the specific thrombin inhibitor hirudin and mimicked by adding low concentrations (< 5 nM) of thrombin to platelet rich plasma. It is our conclusion that, small amounts of thrombin, generated under the influence of thromboplastin induced procoagulant activity in the blood platelets. This activity is most likely mainly due to procoagulant phospholipids. Heparin inhibits this effect and retards the explosive thrombin formation. It does not, however, diminish the peak amount of thrombin eventually formed, because heparin neutralizing material released from the activated platelets quenches the heparin effect.

scholarly journals In Hemophilia Α Plasma Treated with Emicizumab, Factor IX Activation By Factor VIIa Drives Thrombin Generation

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 17-17
Author(s):  
Dougald Monroe ◽  
Mirella Ezban ◽  
Maureane Hoffman
Keyword(s):  
Factor Viii ◽  
Tissue Factor ◽  
Plasma Levels ◽  
Thrombin Generation ◽  
Hemophilia A ◽  
Factor Viia ◽  
Factor Ix ◽  
Factor X ◽  
Dose Dependent

Background.Recently a novel bifunctional antibody (emicizumab) that binds both factor IXa (FIXa) and factor X (FX) has been used to treat hemophilia A. Emicizumab has proven remarkably effective as a prophylactic treatment for hemophilia A; however there are patients that still experience bleeding. An approach to safely and effectively treating this bleeding in hemophilia A patients with inhibitors is recombinant factor VIIa (rFVIIa). When given at therapeutic levels, rFVIIa can enhance tissue factor (TF) dependent activation of FX as well as activating FX independently of TF. At therapeutic levels rFVIIa can also activate FIX. The goal of this study was to assess the role of the FIXa activated by rFVIIa when emicizumab is added to hemophilia A plasma. Methods. Thrombin generation assays were done in plasma using 100 µM lipid and 420 µM Z-Gly-Gly-Arg-AMC with or without emicizumab at 55 µg/mL which is the clinical steady state level. The reactions were initiated with low (1 pM) tissue factor (TF). rFVIIa was added at concentrations of 25-100 nM with 25 nM corresponding to the plasma levels achieved by a single clinical dose of 90 µg/mL. To study to the role of factor IX in the absence of factor VIII, it was necessary to create a double deficient plasma (factors VIII and IX deficient). This was done by taking antigen negative hemophilia B plasma and adding a neutralizing antibody to factor VIII (Haematologic Technologies, Essex Junction, VT, USA). Now varying concentrations of factor IX could be reconstituted into the plasma to give hemophilia A plasma. Results. As expected, in the double deficient plasma with low TF there was essentially no thrombin generation. Also as expected from previous studies, addition of rFVIIa to double deficient plasma gave a dose dependent increase in thrombin generation through activation of FX. Interestingly addition of plasma levels of FIX to the rFVIIa did not increase thrombin generation. Starting from double deficient plasma, as expected emicizumab did not increase thrombin generation since no factor IX was present. Also, in double deficient plasma with rFVIIa, emicizumab did not increase thrombin generation. But in double deficient plasma with FIX and rFVIIa, emicizumab significantly increased thrombin generation. The levels of thrombin generation increased in a dose dependent fashion with higher concentrations of rFVIIa giving higher levels of thrombin generation. Conclusion. Since addition of FIX to the double deficient plasma with rFVIIa did not increase thrombin generation, it suggests that rFVIIa activation of FX is the only source of the FXa needed for thrombin generation. So in the absence of factor VIII (or emicizumab) FIX activation does not contribute to thrombin generation. However, in the presence of emicizumab, while rFVIIa can still activate FX, FIXa formed by rFVIIa can complex with emicizumab to provide an additional source of FX activation. Thus rFVIIa activation of FIX explains the synergistic effect in thrombin generation observed when combining rFVIIa with emicizumab. The generation of FIXa at a site of injury is consistent with the safety profile observed in clinical use. Disclosures Monroe: Novo Nordisk:Research Funding.Ezban:Novo Nordisk:Current Employment.Hoffman:Novo Nordisk:Research Funding.

Significant Correlations between Tissue Factor and Thrombin Markers in Trauma and Septic Patients with Disseminated Intravascular Coagulation

1998 ◽  
Vol 79 (06) ◽  
pp. 1111-1115 ◽  
Author(s):  
Satoshi Nanzaki ◽  
Shigeyuki Sasaki ◽  
Osamu Kemmotsu ◽  
Satoshi Gando
Keyword(s):  
Tissue Factor ◽  
Disseminated Intravascular Coagulation ◽  
Thrombin Generation ◽  
Trauma Patients ◽  
Elevated Plasma ◽  
Antigen Concentration ◽  
Intravascular Coagulation ◽  
Factor Antigen ◽  
D Dimer

SummaryTo determine the role of plasma tissue factor on disseminated intravascular coagulation (DIC) in trauma and septic patients, and also to investigate the relationships between tissue factor and various thrombin markers, we made a prospective cohort study. Forty trauma patients and 20 patients with sepsis were classified into subgroups according to the complication of DIC. Plasma tissue factor antigen concentration (tissue factor), prothrombin fragment F1+2 (PF1+2), thrombin antithrombin complex (TAT), fibrinopeptide A (FPA), and D-dimer were measured on the day of admission (day 0), and on days 1, 2, 3, and 4 after admission. The levels of plasma tissue factor in the DIC group were more elevated than those of the non-DIC group in both the trauma and the septic patients. In patients with sepsis, tissue factor levels on days 0 through 4 in the non-DIC group showed markedly higher values than those in the control patients (135 ± 8 pg/ml). Significant correlations between tissue factor and PF1+2, TAT, FPA, and D-dimer were observed in the DIC patients, however, no such correlations were found in the non-DIC patients. These results suggest that elevated plasma tissue factor in patients with trauma and sepsis gives rise to thrombin generation, followed by intravascular coagulation.

Microparticles Are a Major Determinant of Thrombin Generation Measured by Technothrombin®TGA.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1462-1462
Author(s):  
Viktoria Kaufmann ◽  
Jutta Mager ◽  
Sabine Eichinger ◽  
Bernd R. Binder
Keyword(s):  
Venous Thromboembolism ◽  
Tissue Factor ◽  
Anticoagulant Therapy ◽  
Lupus Anticoagulant ◽  
Thrombin Generation ◽  
Major Determinant ◽  
Clotting Factor ◽  
Platelet Poor Plasma ◽  
Recurrent Venous Thromboembolism ◽  
Free Plasma

Abstract We have recently shown that a thrombin generation assay using low concentrations of phospholipids (3,2 mM; 20% PS) can discriminate patients with an increased risk for recurrent venous thromboembolism after cessation of anticoagulant therapy from those with a lower risk (Hron et al JAMA 2006). Patients with peak thrombin of ≥400nM had a ~3-fold higher relative risk of recurrence than those with peak thrombin <400nM. This difference was not explained by a larger proportion of patients with clotting factor abnormalities among those with high peak thrombin. We therefore investigated which other factors might influence peak thrombin generation. For this purpose 35 healthy male plasma donors were analyzed. Thrombin generation was measured in standard platelet poor plasma and in plasma made microparticle (MP) free by centrifugation for 120 minutes at 35,250 x g using low (3,2μM) and high (32μM ) phospholipids concentrations at the same tissue factor concentration (71,6 pM). For control purposes, peak thrombin was measured under similar conditions in 12 individuals each having either heterozygous FVLeiden mutation, being on vitamin K-antagonist therapy (VKA; mean INR=3.2) or having a lupus anticoagulant. In healthy plasma donors peak thrombin as generated by tissue factor and low phospholipids (RCL) in platelet poor plasma was 110±40 nM and increased to 306±99 nM in the presence of high phospholipids (RCH). When MP free plasma was used, however, peak thrombin dropped to 23±13 nM (RCL) and 109±43 nM thrombin (RCH), respectively. When MPs were re-added to MP-free plasma samples, a dose dependent increase in peak thrombin was found both for RCL and RCH reagents. At a MP concentration of 25,000 added per 1 ml MP free plasma, peak thrombin was 381±24 nM for RCL and 399±63 nM for RCH. The effects of MPs on peak thrombin using RCL were much more pronounced than the differences in peak thrombin seen between plasmas from individuals with FVLeiden, during anticoagulant therapy or with lupus anticoagulant as compared to controls (FVLeiden : 161±50 nM; VKA: 50±12 nM; lupus: 37±23 nM; controls: 110±40 nM). These results indicate that MPs contained in platelet poor plasma are a major determinant of peak thrombin in thrombin generation assays when low phospholipids are used and might cause increased peak thrombin levels found in patients with recurrent venous thromboembolism.

The Concentration of Exogenously Added Lipids and Endogenously Available Microparticles Are Major Determinants of Thrombin Generation in Plasma.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4000-4000
Author(s):  
C. Kluft ◽  
P. Meijer ◽  
R. Kret ◽  
V. Kaufmann ◽  
J. Mager
Keyword(s):  
Tissue Factor ◽  
Thrombin Generation ◽  
Area Under The Curve ◽  
Coagulation Factors ◽  
Factor Ix ◽  
Fixed Amount ◽  
High Lipid ◽  
Factor Ii ◽  
The Difference

Abstract Thrombin generation tests are started by adding coagulation activator (e.g. tissue factor or contact activator) together with lipids. We evaluated the role of lipids in tests started with a fixed amount of tissue factor (7.16 pM) and addition of either 3.2 (high) or 0.32 (low) μM of lipids (Technothrombin ® TGA assays from Technoclone, Vienna) in both normal plasma and plasma that was ultracentrifuged (30 minutes at 15,000 g) to remove microparticles (MPs). The tests were performed in plasma samples of groups of apparently healthy individuals. It was observed in 54 healthy volunteers that starting with high or low lipids substantially influenced the total amount of thrombin generated expressed by the area under the curve (AUC) (AUC median 2492, IQR 716 versus AUC median 1154, IQR 652 nM*min, respectively), the rate of thrombin formation or velocity index (VI) (median 53.4, IQR 43.6 and median 11.7, IQR 10.6 nM/min, respectively), and the lag time to the start of thrombin generation (median 10.3, IQR 2.4 versus median 17.5, IQR 5.0 minutes, respectively). It can be concluded that the VI is the most sensitive variable showing approximately a factor of 5 difference between high and low lipid. The difference of adding high or low lipid on VI was primarily dependent upon the lipid concentration and to a limited extend influenced (univariate) by factor II levels (12%) and factor IX levels (10 %), taking into account practically all known coagulation factors (fibrinogen, II, V, VII, VIII, IX, X, XI, XII, PC, PS, PZ, TFPI, PCI) determined in the 54 plasma’s as potential determinant. In plasma of 36 volunteers microparticles were removed and VI dropped to 19% in comparison to the untreated plasma when tested with the addition of high lipid and to 3.1% with the addition of low lipid. Re-addition of MPs to a specific plasma restored VI dose dependently with an optimum at 2x104 MPs/ml. The same level of VI (63.8 and 62.0 nM/min, respectively) was reached with high and low lipid addition when 2.104 MPs/ml were added. It is concluded that endogenous MPs play an important role in thrombin generation tests, in particular but not exclusively when the test is performed with low levels of added lipids.

Recombinant factor VIIa enhances deposition of platelets with congenital or acquired αIIbβ3 deficiency to endothelial cell matrix and collagen under conditions of flow via tissue factor–independent thrombin generation

Blood ◽  
2003 ◽  
Vol 101 (5) ◽  
pp. 1864-1870 ◽  
Author(s):  
Ton Lisman ◽  
Sultana Moschatsis ◽  
Jelle Adelmeijer ◽  
H. Karel Nieuwenhuis ◽  
Philip G. De Groot
Keyword(s):  
Tissue Factor ◽  
Thrombin Generation ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Umbilical Vein ◽  
Novel Approach ◽  
Platelet Deposition ◽  
Platelet Aggregate ◽  
Umbilical Vein Endothelial Cells ◽  
Thrombin Formation

A novel approach to treat bleeding episodes in patients with Glanzmann thrombasthenia (GT) and perhaps also in patients receiving αIIbβ3 inhibitors is the administration of recombinant factor VIIa (rFVIIa). The mechanism of action of rFVIIa in these patients is, however, still unclear. We studied the effect of rFVIIa-mediated thrombin formation on adhesion of αIIbβ3-deficient platelets under flow conditions. Adhesion of αIIbβ3-deficient platelets to the extracellular matrix (ECM) of stimulated human umbilical vein endothelial cells or to collagen type III was studied using a model system with washed platelets and red cells. When αIIbβ3-deficient platelets were perfused over the surface at arterial shear rate for 5 minutes, a low surface coverage was observed (GT platelets, mean ± SEM, 37.5% ± 5.0%; normal platelets preincubated with an RGD-containing peptide, 7.4% ± 2.1%). When rFVIIa, together with factors X and II, was added to the perfusate, platelet deposition significantly increased (GT platelets, mean ± SEM, 67.0% ± 4.3%; normal platelets preincubated with an RGD-containing peptide, 48.2% ± 2.9%). The same effect was observed when normal platelets were pretreated with the commercially available anti-αIIbβ3 drugs abciximab, eptifibatide, or tirofiban. It was shown that tissue factor–independent thrombin generation (presumably induced by binding of rFVIIa to adhered platelets) was responsible for the increase in platelet deposition. In conclusion, defective adhesion of αIIbβ3-deficient platelets to ECM can be restored by tissue factor–independent rFVIIa-mediated thrombin formation. The enhanced generation of platelet procoagulant surface facilitates fibrin formation, so that lack of platelet aggregate formation might be compensated for.

scholarly journals Thrombin generation in rheumatoid arthritis: Dependence on plasma factor composition

2010 ◽  
Vol 104 (08) ◽  
pp. 224-230 ◽  
Author(s):  
Anetta Undas ◽  
Matthew Gissel ◽  
Beata Kwasny-Krochin ◽  
Piotr Gluszko ◽  
Kenneth Mann ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Tissue Factor ◽  
Cardiovascular Events ◽  
Thrombin Generation ◽  
Protein Composition ◽  
Initiation Phase ◽  
Increased Risk ◽  
Intergroup Comparison ◽  
Plasma Factor ◽  
Thrombin Formation

SummaryGrowing evidence indicates that rheumatoid arthritis (RA) is associated with an increased risk for thromboembolic cardiovascular events. We investigated thrombin generation profiles in RA patients and their dependence on plasma factor/inhibitor composition. Plasma factor (F) compositions (II, V, VII, VIII, IX, X), antithrombin and free tissue factor pathway inhibitor (TFPI) from 46 consecutive RA patients with no cardiovascular events (39 female, 7 male, aged 57 [range, 23–75] years; DAS28 [Disease Activity Score] 5.2 ± 1.1) were compared with those obtained in age- and sex-matched apparently healthy controls. Using each individual’s plasma coagulation protein composition, tissue factor- initiated thrombin generation was assessed both computationally and empirically. RA patients had higher fibrinogen (4.18 [IQR 1.09] vs. 2.56 [0.41] g/l, p<0.0001), FVIII (226 ± 40 vs. 113 ± 15%, p<0.001), PC (107 [16] vs. 100 [14]%, p<0.001), and free TFPI levels (22.3 [2.2] vs. 14.7 [2.1] ng/ml, p<0.001). DAS28, but not age, RA duration, or C-reac- tive protein, was associated with FV, FVIII, FIX, FX, antithrombin, and free TFPI (r from 0.27 to 0.48, p<0.05). Intergroup comparison of computational thrombin generation profiles showed that in RA patients, maximum thrombin levels (p=0.01) and the rate of thrombin formation (p<0.0001) were higher, whereas the initiation phase of thrombin generation (p<0.0001) and the time to maximum thrombin levels (p<0.0001) were longer. Empirical reconstructions of the populations reproduced the thrombin generation profiles generated by the computational model. Simulations of thrombin formation suggest that blood plasma composition, i.e. a marked increase in FVIII, somewhat counterbalanced by free TFPI, contributes to the prothrombotic phenotype in RA patients.

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