scholarly journals A Systems Biology Model for the Coagulation Network in Non-Bleeding State Describes Baseline Activity of Coagulation

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4238-4238
Author(s):  
Dooyoung Lee ◽  
Satyaprakash Nayak ◽  
Debra Pittman ◽  
Steven Arkin ◽  
Steven Martin ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Prothrombin Time ◽  
Tissue Factor ◽  
Thrombin Generation ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Coagulation Activity ◽  
Low Level ◽  
Baseline Activity ◽  
Coagulation Pathway

Abstract Coagulation is a process crucial to stop bleeding from a damaged vessel. The network is comprised of a complex interplay of various pro-coagulant and anti-coagulant factors. Several systems models for the coagulation pathway have been published, as a way to investigate the pathway complexity. Most published models describe the thrombin generation profile (TGA) or prothrombin time (PT) following extrinsic pathway activation by tissue factor, or activated partial prothrombin time (aPTT) through activation of the intrinsic pathway by contact activation. In the clinical setting, thrombin-anti-thrombin complex (TAT) and prothrombin fragment 1+2 (PF1+2) are often used as biomarkers for in vivo coagulation activity in the non-bleeding state. Even in the absence of any treatment, there are detectable levels of PF1+2 and TAT in healthy volunteers indicating low level coagulation activity exists in the normal baseline, non-bleeding state. In this study, we developed a mathematical model for coagulation to describe the baseline activity of PF1+2 and TAT. We then used the model to understand the impact of the coagulation pathway activity during non-bleeding state on thrombin generation activated by tissue factor. First, a coagulation model from Hockin et al. (J Biol Chem. 2002;277(21):18322-33) was modified to describe internally generated data for thrombin generation and aPTT modulation following addition of various concentrations of recombinant factor VIIa or plasma derived factor Xa to normal or hemophilic human plasma. Next, protein synthesis and degradation were incorporated into the model and platelet-dependent reactions were tuned down to describe the baseline coagulation activity in non-bleeding healthy subjects. Using a simulated annealing algorithm, the new parameters were optimized to fit published data for PF1+2 and TAT in healthy volunteers and changes of PF1+2 following treatment with eptacog alfa (recombinant factor VIIa). In the model, the baseline coagulation activities can be described by a very low level of tissue factor, which is much lower than the detection limit of a regular ELISA method. Using this baseline model, we tested the effect of this baseline coagulation activity on tissue factor-activated thrombin generation, and found that very small baseline levels of activated enzymes significantly shorten the lag time of thrombin generation, but did not affect the peak thrombin. We also performed a global sensitivity analysis to identify key proteins in the coagulation network whose modulation will have the biggest impact on PF1+2 and TAT levels. Disclosures Lee: Pfizer Inc.: Employment. Nayak:Pfizer Inc.: Employment. Pittman:Pfizer Inc.: Employment. Arkin:Pfizer Inc.: Employment. Martin:Pfizer Inc.: Employment. Heatherington:Pfizer Inc.: Employment. Vicini:Pfizer Inc.: Employment. Hua:Pfizer Inc: Employment.

The glycoprotein Ib-IX-V complex contributes to tissue factor–independent thrombin generation by recombinant factor VIIa on the activated platelet surface

Blood ◽  
2008 ◽  
Vol 112 (8) ◽  
pp. 3227-3233 ◽  
Author(s):  
Cees Weeterings ◽  
Philip G. de Groot ◽  
Jelle Adelmeijer ◽  
Ton Lisman
Keyword(s):  
Tissue Factor ◽  
Cho Cells ◽  
Thrombin Generation ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Affinity Constant ◽  
Activate Factor ◽  
Platelet Surface ◽  
Static Conditions ◽  
Lines Of Evidence

Abstract Several lines of evidence suggest that recombinant factor VIIa (rFVIIa) is able to activate factor X on an activated platelet, in a tissue factor-independent manner. We hypothesized that, besides the anionic surface, a receptor on the activated platelet surface is involved in this process. Here, we showed that, in an ELISA setup, a purified extracellular fragment of GPIbα bound to immobilized rFVIIa. Surface plasmon resonance established a affinity constant (Kd) of approximately 20 nM for this interaction. In addition, CHO cells transfected with the GPIb-IX-V complex could adhere to immobilized rFVIIa, whereas wild-type CHO cells could not. Furthermore, platelets sti-mulated with a combination of collagen and thrombin adhered to immobilized rFVIIa under static conditions. Platelet adhesion was inhibited by treatment with O-sialoglycoprotein endopeptidase, which specifically cleaves GPIbα from the platelet surface. In addition, rFVIIa-mediated thrombin generation on the activated platelet surface was inhibited by cleaving GPIbα from its surface. In summary, 3 lines of evidence showed that rFVIIa interacts with the GPIb-IX-V complex, and this interaction enhanced tissue factor-independent thrombin generation mediated by rFVIIa on the activated platelet surface. The rFVIIa-GPIbα interaction could contribute to cessation of bleeding after administration of rFVIIa to patients with bleeding disorders.

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 In vitro evidence of a tissue factor-independent mode of action of recombinant factor VIIa in hemophilia

Blood ◽  
2014 ◽  
Vol 124 (20) ◽  
pp. 3172-3174 ◽  
Author(s):  
Cecilia Augustsson ◽  
Egon Persson
Keyword(s):  
Tissue Factor ◽  
Mode Of Action ◽  
Thrombin Generation ◽  
Hemophilia A ◽  
Recombinant Factor Viia ◽  
Negative Impact ◽  
Factor Viia ◽  
Key Points ◽  
Independent Mode

Key Points The negative impact on thrombin generation of zymogen FVII competing with rFVIIa for TF is counteracted by FVII (auto)activation. Correction of hemophilia A occurs in a rFVIIa concentration range where detectable effects of FVII competition are minimal or absent.

Extrinsic Coagulation Pathway Inhibitor during Recombinant Factor VIIa Infusion

1989 ◽  
Vol 62 (04) ◽  
pp. 1146-1146 ◽  
Author(s):  
Per Morten Sandset ◽  
Ulrich Abildgaard ◽  
Ulla Hedner ◽  
Hans Johansson
Keyword(s):  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Coagulation Pathway

The Effect of Active Site-inhibited Factor VIIa on Tissue Factor-initiated Coagulation Using Platelets before and after Aspirin Administration

1997 ◽  
Vol 78 (04) ◽  
pp. 1202-1208 ◽  
Author(s):  
Marianne Kjalke ◽  
Julie A Oliver ◽  
Dougald M Monroe ◽  
Maureane Hoffman ◽  
Mirella Ezban ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Active Site ◽  
Large Scale ◽  
Thrombin Generation ◽  
Factor Viia ◽  
Dependent Manner ◽  
Antithrombotic Agent ◽  
Before And After ◽  
Ic50 Values

SummaryActive site-inactivated factor VIIa has potential as an antithrombotic agent. The effects of D-Phe-L-Phe-L-Arg-chloromethyl ketone-treated factor VIla (FFR-FVIIa) were evaluated in a cell-based system mimicking in vivo initiation of coagulation. FFR-FVIIa inhibited platelet activation (as measured by expression of P-selectin) and subsequent large-scale thrombin generation in a dose-dependent manner with IC50 values of 1.4 ± 0.8 nM (n = 8) and 0.9 ± 0.7 nM (n = 7), respectively. Kd for factor VIIa binding to monocytes ki for FFR-FVIIa competing with factor VIIa were similar (11.4 ± 0.8 pM and 10.6 ± 1.1 pM, respectively), showing that FFR-FVIIa binds to tissue factor in the tenase complex with the same affinity as factor VIIa. Using platelets from volunteers before and after ingestion of aspirin (1.3 g), there were no significant differences in the IC50 values of FFR-FVIIa [after aspirin ingestion, the IC50 values were 1.7 ± 0.9 nM (n = 8) for P-selectin expression, p = 0.37, and 1.4 ± 1.3 nM (n = 7) for thrombin generation, p = 0.38]. This shows that aspirin treatment of platelets does not influence the inhibition of tissue factor-initiated coagulation by FFR-FVIIa, probably because thrombin activation of platelets is not entirely dependent upon expression of thromboxane A2.

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.

Inhibition of thrombin generation by the zymogen factor VII: implications for the treatment of hemophilia A by factor VIIa

Blood ◽  
2000 ◽  
Vol 95 (4) ◽  
pp. 1330-1335 ◽  
Author(s):  
Cornelis van 't Veer ◽  
Neal J. Golden ◽  
Kenneth G. Mann
Keyword(s):  
Factor Viii ◽  
Tissue Factor ◽  
Thrombin Generation ◽  
Hemophilia A ◽  
Factor Viia ◽  
Plasma Concentrations ◽  
Factor Xa ◽  
Factor Vii ◽  
Lag Phase ◽  
Single Chain

Factor VII circulates as a single chain inactive zymogen (10 nmol/L) and a trace (∼10-100 pmol/L) circulates as the 2-chain form, factor VIIa. Factor VII and factor VIIa were studied in a coagulation model using plasma concentrations of purified coagulation factors with reactions initiated with relipidated tissue factor (TF). Factor VII (10 nmol/L) extended the lag phase of thrombin generation initiated by 100 pmol/L factor VIIa and low TF. With the coagulation inhibitors TFPI and AT-III present, factor VII both extended the lag phase of the reaction and depressed the rate of thrombin generation. The inhibition of factor Xa generation by factor VII is consistent with its competition with factor VIIa for TF. Thrombin generation with TF concentrations >100 pmol/L was not inhibited by factor VII. At low tissue factor concentrations (<25 pmol/L) thrombin generation becomes sensitive to the absence of factor VIII. In the absence of factor VIII, factor VII significantly inhibits TF-initiated thrombin generation by 100 pmol/L factor VIIa. In this hemophilia A model, approximately 2 nmol/L factor VIIa is needed to overcome the inhibition of physiologic (10 nmol/L) factor VII. At 10 nmol/L, factor VIIa provided a thrombin generation response in the hemophilia model (0% factor VIII, 10 nmol/L factor VII) equivalent to that observed with normal plasma, (100% factor VIII, 10 nmol/L factor VII, 100 pmol/L factor VIIa). These results suggest that the therapeutic efficacy of factor VIIa in the medical treatment of hemophiliacs with inhibitors is, in part, based on overcoming the factor VII inhibitory effect.

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