Surface Independent Factor XI Activation by Thrombin in the Presence of High Molecular Weight Kininogen

Summary

A deficiency of one of the proteins of the contact system of blood coagulation does not result in a bleeding disorder. For this reason activation of blood coagulation via this system is believed to be an in vitro artefact. However, patients deficient in factor XI do suffer from variable bleeding abnormalities. Recently, an alternative pathway for factor XI activation has been described. Factor XI was found to be activated by thrombin in the presence of dextran sulfate as a surface. However, high molecular weight kininogen (HK), to which factor XI is bound in plasma, and fibrinogen were shown to block this activation suggesting it to be an in vitro phenomenon. We investigated the thrombin-mediated factor XI activation using an amplified detection system consisting of factors IX, VIII and X, which was shown to be very sensitive for factor XIa activity. This assay is approximately 4 to 5 orders of magnitude more sensitive than the normal factor XIa activity assay using a chromogenic substrate. With this assay we found that factor XI activation by thrombin could take place in the absence of dextran sulfate. The initial activation rate was approximately 0.3 pM/min (using 25 nM factor XI and 10 nM thrombin). The presence of dextran sulfate enhanced this rate about 8500-fold. A very rapid and complete factor X activation was observed in the presence of dextran sulfate. Although only minute amounts of factor XIa were formed in the absence of dextran sulfate, significant activation of factor X was detected in the amplification assay within a few minutes. HK inhibited the activation of factor XI by thrombin strongly in the presence, yet only slightly in the absence of dextran sulfate (26 and 1.2 times, respectively). Despite the strong inhibition of HK on the activation of factor XI by thrombin in the presence of dextran sulfate, HK had only a minor effect on the factor Xa generation.

We conclude that activation of factor XI by thrombin can take place regardless of the presence of a surface or HK. This activation might therefore be physiologically relevant. The inhibitory effect of HK on the thrombin-mediated factor XI activation is largely dextran sulfate dependent. Due to the amplification in the intrinsic system, trace amounts of factor XIa might generate physiological sufficient amounts of factor Xa for an adequate haemostatic response.

• References

• 1 Walsh PN. Factor XI: a renaissance. Semin Hematol 1992; 29: 189-201
• 2 Schmaier AH, Silverberg M, Kaplan AP, Colman RW. Contact activation and its abnormalities. In: Hemostasis and Thrombosis, 2nd edition Colman RW, Hirsh J, Marder VJ, Salzman EW. (eds) Philadelphia, PA: Lippincott: JB Lippincott Company; 1987. pp 18-38
• 3 Saito H. Contact factors in health and disease. Semin Thromb Hemostas 1987; 13: 36-49
• 4 Kitchens CS. Factor XI: a review of its biochemistry and deficiency. Semin Thromb Hemostas 1991; 17: 55-72
• 5 Naito K, Fujikawa K. Activation of human blood coagulation factor XI independent of factor XII. Factor XI is activated by thrombin and factor XIa in the presence of negatively charged surfaces. J Biol Chem 1991; 266: 7353-8
• 6 Gailani D, Broze GJ. Factor XI activation in a revised model of blood coagulation. Science 1991; 253: 909-12
• 7 Scott CF, Colman RW. Fibrinogen blocks the autoactivation and thrombin-mediated activation of factor XI on dextran sulfate. Proc Natl Acad Sci USA 1992; 89: 11189-93
• 8 Brunnee T, La Porta C, Reddigari SR, Salerno VM, Kaplan AP, Silverberg M. Activation of factor XI in plasma is dependent on factor XII. Blood 1993; 81: 580-6
• 9 Gailani D, Broze GJ. Factor XH-independent activation of factor XI in plasma: Effects of sulfatides on tissue factor induced coagulation. Blood 1993; 82: 813-9
• 10 Kerbiriou DM, Griffin JH. Human high molecular weight kininogen. Studies on structure-function relationships of proteolysis of the molecule occurring during contact activation in plasma. J Biol Chem 1979; 254: 12020-7
• 11 Miletich JP, Jackson CM, Majerus PW. Properties of the factor Xa binding site on platelets. J Biol Chem 1978; 253: 6908-16
• 12 Meijers JCM. Regulation of the blood coagulation mechanism by plasma proteinase inhibitors. Ph. D. Thesis State University of Utrecht; The Netherlands: 1988. pp 93-108
• 13 Van der Graaf F, Greengard JS, Bouma BN, Kerbiriou DM, Griffin JH. Isolation and functional characterization of the active light chain of activated human blood coagulation factor XI. J Biol Chem 1983; 258: 9669-75
• 14 Meijers JCM, Tijburg PNM, Bouma BN. Inhibition of human blood coagulation factor Xaby a2-macroglobulin. Biochemistry 1987; 26: 5932-7
• 15 Brunner J, Skrabal P, Hauser H. Single bilayer vesicles prepared without sonication. Physico-chemical properties. Biochim Biophys Acta 1976; 455: 322-31
• 16 Rouser G, Fleisher S, Yamamoto A. Two dimensional thin layer chromatographic separation of polar lipids and determination of phospholipid by phosphorus analysis of spots. Lipids 1970; 5: 494-6
• 17 Burrie BJ, Edgington TS, Fair DS. Molecular interactions of the intrinsic activation complex of coagulation: binding of native and activated human factors IX and X to defined phospholipid vesicles. Biochimica et Biophysi-ca Acta 1987; 923: 176-86
• 18 Davie EW, Fujikawa K, Kisiel W. The coagulation cascade: initiation, maintenance and regulation. Biochemistry 1991; 30: 10363-70
• 19 Stirling D, Ludlam CA. Therapeutic concentrates for the treatment of congenital deficiencies of factors VII, XI and XIII. Semin Thromb Hemostas 1993; 19: 48-53
• 20 Santagostino E, Gringeri A, Bottasso B, Bauer K, Mannucci PM. Abnormal activation of the coagulation cascade after a highly purified factor XI concentrate. Thromb Haemost 1993; 69: 968 (abstr)
• 21 Oohira A, Wight TN, Bornstein P. Sulfated proteoglycans synthesized by vascular endothelial cells in culture. J Biol Chem 1983; 258: 2014-21
• 22 Mosesson MW. The roles of fibrinogen and fibrin in hemostasis and thrombosis. Semin Hematol 1992; 29: 177-88