Thromb Haemost 2012; 107(05): 972-984
DOI: 10.1160/TH11-09-0604
Animal Models
Schattauer GmbH

Reduction of thrombus size in murine models of thrombosis following administration of recombinant α1-proteinase inhibitor mutant proteins

William P. Sheffield
1   Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
2   Canadian Blood Services, Research and Development, Hamilton, Ontario, Canada
,
Louise J. Eltringham-Smith
1   Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
,
Varsha Bhakta
2   Canadian Blood Services, Research and Development, Hamilton, Ontario, Canada
,
Sharon Gataiance
1   Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
› Author Affiliations

Financial support: This work was made possible by Grant-In-Aid T6271 from the Heart and Stroke Foundation of Ontario to WPS.
Further Information

Publication History

Received: 01 September 2011

Accepted after minor revision: 02 February 2012

Publication Date:
25 November 2017 (online)

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Summary

The variant serpin α1-PI M358R inhibits thrombin and other proteases such as activated protein C (APC) and factor XIa. We previously described recombinant proteins HAPI M358R (α1-PI M358R containing an N-terminal extension corresponding to residues 1–75 of heparin cofactor II) and HAPI RCL5 (HAPI M358R with F352-I356 and I360 substituted for the corresponding residues of antithrombin), with enhanced selectivity for thrombin over APC inhibition. We tested the hypotheses that these recombinant proteins would limit thrombosis in three mouse models, and that the HAPI chimeric proteins would be more effective than α1-PI M358R. Recombinant serpins were purified from Escherichia coli by nickel chelate and ion exchange affinity chromatography, and administered to mice intravenously. HAPI RCL5 reduced incorporation of radiolabelled fibrin(ogen) into thrombi in the ferric chloride-injured vena cava in a dose-dependent manner; HAPI M358R was less effective and α1-PI M358R was without effect. In a model of murine endotoxaemia, HAPI RCL5 was more effective than α1-PI M358R in reducing radiolabelled fibrin(ogen) deposition in heart and kidneys; immunohis-tochemistry of tissue sections showed lesser staining with anti-fibrin(ogen) antibodies with both treatments. In the ferric chloride-injured murine carotid artery, administration of both recombinant serpins was equally effective in lengthening the vessel’s time to occlusion. Our results show that the antithrombotic efficacy of the recombinant serpins correlates with their potency as thrombin inhibitors, since HAPI RCL5 inhibits thrombin, but not factors Xa, XIa, XIIa, or neutrophil elastase, more rapidly than α1-PI M358R.