Congress of the International Society on Thrombosis and Haemostasis

Prolonged survival following microbial infection in mice expressing the thrombin anticoagulant mutant W215/E217A

Abstract number: OC-TH-063

Flick¹ M.J., Chauhan² A.K., Mullins³ E.S., Palumbo³ J.S., Thornton¹ S., Zheng⁴ X., Esmon⁴ N.L., Esmon⁵ C.T., Wagner² D.D., Degen⁶ J.L.

¹¹Division of Rheumatology, Cincinnati Children's Hospital, Cincinnati ²²CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston ³³Division of Hematology/Oncology, Cincinnati Children's Hospital, Cincinnati ⁴⁴Department of Pathology ⁵⁵Howard Hughes Medical Institute; Departments of Biochemistry and Molecular Biology and Pathology, University of Oklahoma Health Sciences Center, Oklahoma City ⁶⁶Division of Developmental Biology, Cincinnati Children's Hospital, Cincinnati, OH, USA

How-to-cite Flick MJ, Chauhan AK, Mullins ES, Palumbo JS, Thornton S, Zheng X, Esmon NL, Esmon CT, Wagner DD, Degen JL. Prolonged survival following microbial infection in mice expressing the thrombin anticoagulant mutant W215/E217A. Journal of Thrombosis and Haemostasis 2009; Volume 7, Supplement 2: Abstract OC-TH-063

Thrombin is both a positive mediator of thrombus formation through the activation of PARs, fibrinogen, fXI and other substrates, and a negative regulator of coagulation through activation of protein C. Mutagenesis studies have shown that the thrombin active site substitutions W215A/E217A (fII^WE) dramatically reduce catalytic efficiency with fibrinogen and PARs while only modestly reducing activity for protein C. To explore the hypothesis that a thrombin specificity switch favoring an antithrombotic phenotype would limit inflammatory processes in vivo, we generated mice carrying the fII^WE mutations within the endogenous prothrombin gene. The mutant allele supported normal expression of hepatic mRNA and plasma protein. Homozygous fII^WE mice developed normally and were observed at term with Mendelian frequency but uniformly succumbed to spontaneous bleeding events in the perinatal period. Heterozygous fII^WE/WT animals survived through adulthood and unchallenged mice displayed a normal hematological profile. Consistent with a predicted anticoagulant phenotype, fII^WE/WT mice exhibited prolonged tail-bleeding times and significantly extended in vivo thrombus formation times following FeCl₃ injury of mesenteric arterioles relative to WT mice. We explored whether the shift in thrombin specificity would render animals tolerant to acute septic challenges. The survival profile of fII^WT/WE mice was identical to WT animals following LPS challenge. However, following intravenous administration of S. aureus, a significant survival advantage was observed for fII^WT/WE mice over a 7-day observation period. A survival advantage following i.v. S. aureus challenge also was observed for both mice genetically altered to express low levels (e.g., 10%) of WT prothrombin and for fibrinogen-deficient mice. These studies suggest that there is a context dependent benefit to diminished pro-coagulant function following inflammatory challenge.

Disclosure of interest: none declared.

To cite this abstract use the following format:

Journal of Thrombosis and Haemostasis 2007; Volume 5, Supplement 2: abstract number

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Date:	Unpresented
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Session name:	ISTH2009
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