Different mechanisms contribute to the biphasic pattern of carboxypeptidase U (TAFIa) generation during in vitro clot lysis in human plasma

2003 ◽  
Vol 89 (02) ◽  
pp. 264-271 ◽  
Author(s):  
Judith Leurs ◽  
Britt-Marie Wissing ◽  
Viveca Nerme ◽  
Katinka Schatteman ◽  
Petter Björquist ◽  
...  

SummaryCarboxypeptidase U (CPU, TAFIa) recently gained interest as a significant player in dampening the fibrinolytic rate. The aim of this study was to investigate the time course of the generation of CPU activity during coagulation and fibrinolysis using an in vitro clot lysis model in human plasma. A first peak of CPU activity appeared after initiation of the coagulation phase and a second rise in CPU activity was observed during the fibrinolysis. The decrease in the proCPU plasma concentration followed the same trend as the appearance of the CPU activity. The direct thrombin inhibitor inogatran eliminated the CPU generation during coagulation but not during fibrinolysis. Addition of the plasmin inhibitor aprotinin during fibrinolysis resulted in a decrease in CPU activation during the lysis phase. These results demonstrate that proCPU was activated during coagulation by thrombin and during fibrinolysis by plasmin. Addition of a CPU inhibitor before initiation of clotting decreased the clot lysis time as expected. However, addition in the time period between the two peaks of CPU activity had no apparent effect on the clot lysis time.

1987 ◽  
Author(s):  
D Thorir ◽  
M D Bjornsson ◽  
Henry Berger

In addition to its antiplatelet effect, aspirin has been reported to have fibrinolytic and hypoprothrombinémie effects. The objective of this study was to investigate possible mechanisms underlying the enhanced fibrinolysis observed after aspirin. Five healthy subjects received 650 mg of aspirin ql2hr for five days. Blood samples were collected before aspirin (control) and immediately before (0 hr) and two hours after (2 hr) the last dose for determinations of clot lysis time, time course of thrombin-induced fibrin aggregation, tissue plasminogen activator (tPA), intrinsic pathway fibrinolytic activity (IPFA), plasminogen, fibrinogen, aspirin and salicylic acid, and the coagulation tests activated partial thromboplastin time, thrombin time and prothrombin time. Clot lysis time was shorter after aspirin, control: 9.1±12.4 min (mean±s.d.), 0 hr: 4.6±4.0 min, 2 hr: 5.7±6.2 min (p:0.04), and the fibrin aggregation curves showed increased turbidity (expressed as AUC over 10 min), control: 72.7±17.8 mnumin, 0 hr: 94.6±1.6 mnumin, 2 hr: 112.8±45.1 mnumin (p:0.02). Control values of tPA (0.11±0.04 IU/ml), IPFA (2.20±0.59 IU/ml), plasminogen (10.9±1.0 mg/dl), fibrinogen (288±37 mg/dl), and the coagulation tests were not differnet from those after aspirin. Plasma aspirin concentrations were below detection limits at 0 hr and averaged 1.63±0.97μg/ml at 2 hr. In vitro studies using fibrinogen-free plasma and added acetylated fibrinogen sfiowed an inverse relationship between the extent of acétylation and clot lysis time. Studies using 14C-acetyl-labeled aspirin and fibrinogen showed that fibrinogen is acetylated to form ε-N-acetyl-lysine on both D and E domains of the molecule (50.6±2.0 and 49.4±2.0%, respectively) and on α β and γchains of the molecule (34.4±1.6, 30.7±3.4 and 34.9±4.7%, respectively), with preferential acétylation on the E domain. On the average, 2.88±1.49 ε-N-acetyl-lysyl residues were formed on each fibrinogen molecule. These results suggest that N-acetylation of lysyl residues of fibrinogen is responsible for the increased susceptibility of fibrin clots to lysis after aspirin.


2011 ◽  
Vol 106 (07) ◽  
pp. 90-101 ◽  
Author(s):  
Niraj Mishra ◽  
Ellen Vercauteren ◽  
Jan Develter ◽  
Riet Bammens ◽  
Paul J. Declerck ◽  
...  

SummaryThrombin activatable fibrinolysis inhibitor (TAFI) forms a molecular link between coagulation and fibrinolysis and is a putative target to develop profibrinolytic drugs. Out of a panel of monoclonal antibodies (MA) raised against TAFI-ACIIYQ, we selected MA-TCK11A9, MA-TCK22G2 and MA-TCK27A4, which revealed high affinity towards human TAFITI- wt. MA-TCK11A9 was able to inhibit mainly plasmin-mediated TAFI activation, MA-TCK22G2 inhibited plasmin- and thrombin-mediated TAFI activation and MA-TCK27A4 inhibited TAFI activation by plasmin, thrombin and thrombin/thrombomodulin (T/TM) in a dose-dependent manner. These MA did not interfere with TAFIa activity. Using an eightfold molar excess of MA over TAFI, all three MA were able to reduce clot lysis time significantly, i.e. in the presence of exogenous TM, MATCK11A9, MA-TCK22G2 and MA-TCK27A4 reduced clot lysis time by 47 ± 9.1%, 80 ± 8.6% and 92 ± 14%, respectively, compared to PTCI. This effect was even more pronounced in the absence of TM i.e. MATCK11A9, MA-TCK22G2 and MA-TCK27A4 reduced clot lysis time by 90 ± 14%, 140 ± 12% and 147 ± 29%, respectively, compared to PTCI. Mutagenesis analysis revealed that residues at position 268, 272 and 276 are involved in the binding of MA-TCK11A9, residues 147 and 148 in the binding of MA-TCK22G2 and residue 113 in the binding of MATCK27A4. The present study identified three MA, with distinct epitopes, that impair the activation of human TAFI and demonstrated that MATCK11A9 which mainly impairs plasmin-mediated TAFI activation can also reduce significantly clot lysis time in vitro.


1975 ◽  
Author(s):  
N. Aoki ◽  
M. Matsuda ◽  
M. Moroi ◽  
N. Yoshida

A fraction of human plasma prolongs the activator-induced clot lysis time and inhibits plasminogen activation by the plasminogen activators derived from various sources (urine and tissues). This fraction, designated as antiactivator fraction, was separatid from antiplasmin fractions (α2-macroglobulin and α1-antitrypsin) by gel filtration and affinity chromatography on Sepharose coupled with IgG of antiserum to α1-antitrypsin. Anti-activator fraction thus obtained exerted little antiplasmin activity but inhibited strongly activator-induced clot lysis.Inhibitory effect of plasma on urokinase-induced clot lysis (antiactivator activity) was assayed in various diseases and compared with antiplasmin activity. No correlation was found between the two activities, and it was concluded that the two activities are independent and are ascribed to two different entities.


Blood ◽  
2002 ◽  
Vol 99 (1) ◽  
pp. 175-179 ◽  
Author(s):  
Ton Lisman ◽  
Laurent O. Mosnier ◽  
Thierry Lambert ◽  
Evelien P. Mauser-Bunschoten ◽  
Joost C. M. Meijers ◽  
...  

Recombinant factor VIIa (rFVIIa) is a novel prohemostatic drug for patients with hemophilia who have developed inhibitory antibodies. The postulation has been made that hemophilia is not only a disorder of coagulation, but that hyperfibrinolysis due to a defective activation of thrombin activatable fibrinolysis inhibitor (TAFI) might also play a role. In this in vitro study, the potential of rFVIIa to down-regulate fibrinolysis via activation of TAFI was investigated. rFVIIa was able to prolong clot lysis time in plasmas from 17 patients with severe hemophilia A. The prolongation of clot lysis time by rFVIIa was completely abolished by addition of an inhibitor of activated TAFI. The concentration of rFVIIa required for half maximal prolongation of clot lysis time (Clys½-VIIa) varied widely between patients (median, 73.0 U/mL; range, 10.8-250 U/mL). The concentration of rFVIIa required for half maximal reduction of clotting time (Cclot½-VIIa) was approximately 10-fold lower than the Clys½-VIIa value (median, 8.4 U/mL; range, 1.7-22.5 U/mL). Inhibition of TFPI with a polyclonal antibody significantly decreased Clys½-VIIa values (median, 2.6 U/mL; range, 0-86.9 U/mL), whereas Cclot½-VIIa values did not change (median, 7.2 U/mL; range, 2.2-22.5 U/mL). On addition of 100 ng/mL recombinant full-length TFPI, a nonsignificant increase of Clys½-VIIa values was observed (median, 119.2 U/mL; range, 12.3-375.0 U/mL), whereas Cclot½-VIIa values did not change (median, 8.8 U/mL; range, 2.6-34.6 U/mL). In conclusion, this study shows that rFVIIa both accelerates clot formation and inhibits fibrinolysis by activation of TAFI in factor VIII-deficient plasma. However, a large variability in antifibrinolytic potential of rFVIIa exists between patients.


2017 ◽  
Vol 117 (08) ◽  
pp. 1498-1508 ◽  
Author(s):  
Dorien Leenaerts ◽  
Jef Aernouts ◽  
Pieter Van Der Veken ◽  
Yani Sim ◽  
Anne-Marie Lambeir ◽  
...  

SummaryCarboxypeptidase U (CPU, CPB2, TAFIa) is a basic carboxypeptidase that is able to attenuate fibrinolysis. The inactive precursor procarboxypeptidase U is converted to its active form by thrombin, the thrombin-thrombomodulin complex or plasmin. The aim of this study was to investigate and characterise the time course of CPU generation in healthy individuals. In plasma of 29 healthy volunteers, CPU generation was monitored during in vitro clot lysis. CPU activity was measured by means of an enzymatic assay that uses the specific substrate Bz-o-cyano-Phe-Arg. An algorithm was written to plot the CPU generation curve and calculate the parameters that define it. In all individuals, CPU generation was biphasic. Marked inter-individual differences were present and a reference range was determined. The endogenous CPU generation potential is the composite effect of multiple factors. With respect to the first CPU activity peak characteristics, we found correlations with baseline proCPU concentration, proCPU Thr325Ile polymorphism, time to clot initiation and the clot lysis time. The second CPU peak related with baseline proCPU levels and with the maximum turbidity of the clot lysis profile. In conclusion, our method offers a technique to determine the endogenous CPU generation potential of an individual. The parameters obtained by the method quantitatively describe the different mechanisms that influence CPU generation during the complex interplay between coagulation and fibrinolysis, which are in line with the threshold hypothesis.Supplementary Material to this article is available online at www.thrombosis-online.com.


1982 ◽  
Vol 47 (03) ◽  
pp. 254-258 ◽  
Author(s):  
J Dalsgaard-Nielsen ◽  
S Madsbad ◽  
J Hilsted

SummaryHaemostatic parameters were assessed before insulin induced hypoglycaemia and 0, 1 and 2 fu after discontinuation of insulin infusion in 7 non-diabetics, aged 28 (22-31) years (mean and range), and 8 juvenile diabetics, aged 3L (27-35) years, with a mean duration of diabetes of 4 years. The patients were normoglycaemic for at least L0 hr before the study.Platelet aggregation in vitro was induced by lower adenosine diphosphate (ADP) concentrations in the diabetics than in the controls before hypoglycaemia and 0 and 60 min after insulin infusion. Platelet counts decreased significantly in the diabetics after hypoglycaemia, whereas no changes were seen in the control group. The activated partial thromboplastin time (APTT) was reduced in both groups and significantly lower in the diabetics than in the controls 120 min after insulin infusion.Fibrinogen and factor VIII R: Ag increased after insulin infusion; highest values were seen in the diabetics. The euglobulin clot lysis time (ELT) was reduced in both groups during insulin infusion; L20 min after end of insulin infusion ELT was significantly longer in the diabetics than in the control group.


1979 ◽  
Author(s):  
Sandbjerg M. Hansen ◽  
I. Clemmensen

An inhibitor (I) of the plasma proteinase plasmin (P)(EC 3.4.21.7) was partially purified from washed and lysed human blood platelets by ammani sulphate fractionation and affinity chromatography. The material contain none of the known plasma proteinase inhibitors when studied by crossed ir munoelectraphoresis (CIE) and elee troimmuno assay, but inhibited a clot lysis time assay and an esterolytic assay using the synthetic substrate 2251 (O-Val-Leu-Lys-pNA), The inhibitory activity was found in the alpha region by preparative agarose gel electrophoresis (AGE). Titration of the I preparation by active-site titrated P showed a linear relationship untj zero activity indicating a strong binding of I to P. The inhibition was complete within one minute. The I changed the mobility in AGE af activator-free P or 125-I-P from the gamma region to the alpha-2 region as demoi strated by CIE against specific immunoglobulins against plasminogen or by autoradiography. An antibody against I has been raised in rabbits. The results strongly suggests the presence in platelets of a plasmin inhibitor different from the known plasma proteinase inhibitors.


Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3786-3786
Author(s):  
Yoshiyuki Morishima ◽  
Yuko Honda ◽  
Taketoshi Furugohri

Abstract Introduction: Direct oral anticoagulants are as effective as vitamin K antagonists for the treatment of venous thromboembolism and are associated with less bleeding. We have reported that a direct oral factor Xa inhibitor edoxaban exerts a thrombus resolution effect in a rat model of venous thrombosis and enhances tissue plasminogen activator (t-PA)-induced clot lysis in human plasma. However, the mechanism underlying the thrombus resolution effect and fibrinolysis enhancement by edoxaban remains to be determined. Purposes: To evaluate the effect of edoxaban on plasmin generation during clot lysis in human plasma in vitro. To determine the role of thrombin-activatable fibrinolysis inhibitor (TAFI) in the enhancement of fibrinolysis by edoxaban. Methods: Pooled human normal plasma or TAFI-deficient plasma (both containing 180 ng/mL t-PA and 0.1 nM thrombomodulin) was mixed with edoxaban, an activated TAFI (TAFIa) inhibitor (a fibrinolysis enhancer) potato tuber carboxypeptidase inhibitor (PCI), or vehicle. Clot was induced by adding 2.5 pM tissue factor and 4 µM phospholipids. To monitor the clot formation and lysis, the absorbance of plasma at 405 nm was measured every 30 sec. Clot lysis time was defined as the interval between the time of the midpoint of the clear to maximum turbidity transition and the midpoint of the maximum turbidity to clear transition. Plasmin-α2 antiplasmin complex (PAP) concentration was measured by ELISA as an indicator of plasmin generation. Results: In normal plasma, PCI accelerated clot lysis and increased plasma PAP concentration. There was a correlation between plasma PAP concentration and percent of clot lysis, indicating that plasma PAP concentration is an appropriate marker of fibrinolysis. Edoxaban at clinically relevant concentrations (75, 150, and 300 ng/mL) significantly shortened clot lysis time and elevated plasma PAP concentration. The additive combined effect of edoxaban and PCI was observed. In TAFI-deficient plasma, clot lysis time was shortened and plasma PAP concentration increased compared with normal plasma. In these samples, the effects of edoxaban and PCI on clot lysis and plasma PAP concentration were markedly diminished as compared with normal plasma. Conclusions: Edoxaban at clinically relevant concentrations enhanced t-PA-induced clot lysis with increasing plasma PAP concentration in human plasma. The effects of edoxaban on clot lysis and plasmin generation were diminished in TAFI-deficient plasma. A TAFIa inhibitor PCI exerted similar effects. These data suggest that edoxaban enhanced fibrinolysis via inhibition of TAFI activation and enhancement of plasmin generation. Disclosures Morishima: Daiichi Sankyo Co., Ltd.: Employment. Honda:Daiichi Sankyo Co., Ltd.: Employment. Furugohri:Daiichi Sankyo Co., Ltd.: Employment.


1986 ◽  
Vol 56 (01) ◽  
pp. 028-034 ◽  
Author(s):  
Y Tamao ◽  
T Yamamoto ◽  
R Kikumoto ◽  
H Hara ◽  
J Itoh ◽  
...  

SummaryThe effect of a selective thrombin inhibitor, (2R, 4R)-4-methyl-1- [N2- [(3-methyl-1,2,3,4-tetrahydro-8-quinolinyl)sulfo-nyl]-L-arginyl]-2-piperidinecarboxylic acid (MCI-9038), on the fibrinolysis induced by t-PA and u-PA was studied in vitro and in vivo. MCI-9038 remarkably reduced the lysis time of the plasma clot generated by the addition of calcium chloride to the plasma at the concentration ranging from 0.01 to 0.3 μM. Heparin also reduced the plasma clot lysis time with a lower effect than MCI-9038. The fibrin crosslinkage in the plasma clot was inhibited by MCI-9038 or heparin. MCI-9038 potently inhibited the factor XIIIa generation from factor XIII by thrombin.The effect on the in vivo thrombolysis was studied on the arterial thrombosis generated by the endothelial cell injury of the rabbit carotid artery by acetic acid. t-PA dissolved the thrombi with the infusion at 0.96 mg/kg over 2 h without a significant activation of a systemic fibrinolysis. u-PA dissolved the thrombi with the infusion at 180,000 and 360,000 IU/kg over 2 h. At a dose of 0.48 mg/kg t-PA or 90,000 IU/kg u-PA, the thrombi were not dissolved, but the combined use of MCI-9038 at 1.2 mg/kg over 2 h effectively dissolved the thrombi. Thus, combination of MCI-9038 with plasminogen activators accelerated thrombolysis of an experimental thrombosis in rabbits.


1987 ◽  
Author(s):  
Y Sakata ◽  
J Mimuro ◽  
Y koike

A Monoclonal antibody (MCA) against α2-plasmin inhibitor α2-Pl) designated as JTP-1 inhibited antiplasmin act ivity and complex formation of a2-PI with plasmin. By using this MCA we tried to observe plasma-clot lysis (CL) in vitro and to estimate the level of total fibrinolytic capacity in plasma. As reported previously (Blood 55: U83, 1980) spontaneous CL is a striking feature of the plasma derived from a patient with α2-PI deficiency. We showed that this abnormally increased fibrinolysis was solely due to the deficiency of α2-PI. However, the contribution of plasminogen activator (PA) and its inhibitor to this specific patient' plasma -CL has been under discussion. Therefore, to test whether similar CL can be found in normal plasma without an addition of PA, plasma clots were made after incubation of plasma from normal volunteers containing 125i fibrinogen with various concentration of JTP-1, and fibrinolysis was measured by counting the soluble radioactivity. The addition of JTP-1 to plasma led to a dose-dependent enhancement of the soluble 125i fragment-release from the clot. However, JTP-1 had no effect on a2-PI-deficient plasma-CL. Other anti-a2-PI MCAs whose epitopes were not involved in the reactive site of a2-PI had no effect on CL and rabbit anti-mouse immunoglobulin IgG neutralized this JTP-l-inducing CL completely. Immunodepletion of tissue PA (tPA) or plasminogen from plasma decreased the rate of CL but that of prourokinase did not. To determine the role of PA inhibitor (PAl) released from platelets (pits) in the regulation of CL in vitro, plasma clots were made from pits poor plasma (PPP) and pits rich plasma (PRP), and CL was observed in the presence of JTP-1. There was almost no difference of the lysis time between PPP clot and PRP clot, although plasma clot from pregnant woman was lysed slowly. These results strongly suggest that endogenous t-PA in plasma is still functionally active after blood collection and CL is mainly prevented by a2-PI in vitro.-plasmin inhibitor (a2-Pl) designated as JTP-1 inhibited antiplasmin act ivity and complex formation of a2-PI with plasmin. By using this MCA we tried to observe plasma-clot lysis (CL) in vitro and to estimate the level of total fibrinolytic capacity in plasma. As reported previously (Blood 55: U83, 1980) spontaneous CL is a striking feature of the plasma derived from a patient with a2-PI deficiency. We showed that this abnormally increased fibrinolysis was solely due to the deficiency of a2-PI. However, the contribution of plasminogen activator (PA) and its inhibitor to this specific patient' plasma -CL has been under discussion. Therefore, to test whether similar CL can be found in normal plasma without an addition of PA, plasma clots were made after incubation of plasma from normal volunteers containing 125i fibrinogen with various concentration of JTP-1, and fibrinolysis was measured by counting the soluble radioactivity. The addition of JTP-1 to plasma led to a dose-dependent enhancement of the soluble 125i fragment-release from the clot. However, JTP-1 had no effect on a2-PI-deficient plasma-CL. Other anti-a2-PI MCAs whose epitopes were not involved in the reactive site of a2-PI had no effect on CL and rabbit anti-mouse immunoglobulin IgG neutralized this JTP-l-inducing CL completely. Immunodepletion of tissue PA (tPA) or plasminogen from plasma decreased the rate of CL but that of prourokinase did not. To determine the role of PA inhibitor (PAl) released from platelets (pits) in the regulation of CL in vitro, plasma clots were made from pits poor plasma (PPP) and pits rich plasma (PRP), and CL was observed in the presence of JTP-1. There was almost no difference of the lysis time between PPP clot and PRP clot, although plasma clot from pregnant woman was lysed slowly. These results strongly suggest that endogenous t-PA in plasma is still functionally active after blood collection and CL is mainly prevented by a2-PI in vitro.-plasmin inhibitor (a2-Pl) designated as JTP-1 inhibited antiplasmin act ivity and complex formation of a2-PI with plasmin. By using this MCA we tried to observe plasma-clot lysis (CL) in vitro and to estimate the level of total fibrinolytic capacity in plasma. As reported previously (Blood 55: U83, 1980) spontaneous CL is a striking feature of the plasma derived from a patient with α2-PI deficiency. We showed that this abnormally increased fibrinolysis was solely due to the deficiency of a2-PI. However, the contribution of plasminogen activator (PA) and its inhibitor to this specific patient' plasma -CL has been under discussion. Therefore, to test whether similar CL can be found in normal plasma without an addition of PA, plasma clots were made after incubation of plasma from normal volunteers containing 125i fibrinogen with various concentration of JTP-1, and fibrinolysis was measured by counting the soluble radioactivity. The addition of JTP-1 to plasma led to a dose-dependent enhancement of the soluble 125i fragment-release from the clot. However, JTP-1 had no effect on a2-PI-deficient plasma-CL. Other anti-a2-PI MCAs whose epitopes were not involved in the reactive site of a2-PI had no effect on CL and rabbit anti-mouse immunoglobulin IgG neutralized this JTP-l-inducing CL completely. Immunodepletion of tissue PA (tPA) or plasminogen from plasma decreased the rate of CL but that of prourokinase did not. To determine the role of PA inhibitor (PAl) released from platelets (pits) in the regulation of CL in vitro, plasma clots were made from pits poor plasma (PPP) and pits rich plasma (PRP), and CL was observed in the presence of JTP-1. There was almost no difference of the lysis time between PPP clot and PRP clot, although plasma clot from pregnant woman was lysed slowly. These results strongly suggest that endogenous t-PA in plasma is still functionally active after blood collection and CL is mainly prevented by α2-PI in vitro.


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