title: Effects of plasma kallikrein deficiency on haemostasis and thrombosis in mice: murine ortholog of the Fletcher trait.
abstract: Plasma kallikrein is a multifunctional serine protease involved in contact activation of coagulation. Deficiency in humans is characterised by prolonged activated partial thromboplastin time (aPTT); however, the balance between thrombosis and haemostasis is not fully understood. A study of plasma kallikrein-deficient mice revealed increased aPTT, without prolonged bleeding time. Prekallikrein antisense oligonucleotide (ASO) treatment in mice suggested potential for a positive therapeutic index. The current goal was to further define the role of plasma kallikrein in coagulation. Blood pressure and heart rate were normal in plasma kallikrein-deficient mice, and mice were completely protected from occlusion (100 ± 1.3% control flow) in 3.5% FeCl3 -induced arterial thrombosis versus heterozygotes (20 ± 11.4%) and wild-type littermates (8 ± 0%). Vessels occluded in 8/8 wild-type, 7/8 heterozygotes, and 0/8 knockouts. Anti-thrombotic protection was less pronounced in 5% FeCl3-induced arterial injury. Integrated blood flow was 8 ± 0% control in wild-type and heterozygotes, and significantly (p<0.01) improved to 43 ± 14.2% in knockouts. The number of vessels occluded was similar in all genotypes. Thrombus weight was significantly reduced in knockouts (-47%) and heterozygotes (-23%) versus wild-type in oxidative venous thrombosis. Average tail bleeding time increased modestly in knockout mice compared to wild-type. Average renal bleeding times were similar in all genotypes. These studies confirm and extend studies with prekallikrein ASO, and demonstrate that plasma kallikrein deletion prevents occlusive thrombus formation in mice with a minimal role in provoked bleeding. Additional support for the significance of the intrinsic pathway in the coagulation cascade is provided, as well as for a potential new anti-thrombotic approach.
authors.affiliation: Department of Thrombosis Biology, Bristol-Myers Squibb, Pennington, New Jersey 08534, USA. eileen.bird@bms.com
authors.forename: J Eileen
authors.initials: JE
authors.lastname: Bird
authors.forename: Patricia L
authors.initials: PL
authors.lastname: Smith
authors.forename: Xinkang
authors.initials: X
authors.lastname: Wang
authors.forename: William A
authors.initials: WA
authors.lastname: Schumacher
authors.forename: Frank
authors.initials: F
authors.lastname: Barbera
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Revelli
authors.forename: Dietmar
authors.initials: D
authors.lastname: Seiffert
mesh_terms: D000818:Animals; D001760:Bleeding Time; D002712:Chlorides; D004195:Disease Models, Animal; D005290:Ferric Compounds; D006470:Hemorrhage / Q000097:blood / Q000235:genetics; D006487:Hemostasis / Q000235:genetics; D006579:Heterozygote; D051379:Mice; D018345:Mice, Knockout; D016376:Oligonucleotides, Antisense / Q000378:metabolism; D010314:Partial Thromboplastin Time; D010641:Phenotype; D020842:Plasma Kallikrein / Q000235:genetics / Q000378:metabolism*; D011288:Prekallikrein / Q000235:genetics / Q000378:metabolism*; D013927:Thrombosis / Q000097:blood / Q000139:chemically induced / Q000235:genetics / Q000517:prevention & control*; D013997:Time Factors; D020246:Venous Thrombosis / Q000097:blood / Q000139:chemically induced / Q000235:genetics / Q000517:prevention & control
chemical_list: D002712:Chlorides; D005290:Ferric Compounds; D016376:Oligonucleotides, Antisense; D011288:Prekallikrein; D020842:Plasma Kallikrein; C024555:ferric chloride