Thromb Haemost 2010; 104(06): 1116-1123
DOI: 10.1160/TH10-03-0186
Blood Coagulation, Fibrinolysis and Cellular Haemostasis
Schattauer GmbH

Nitrophorin 2, a factor IX(a)-directed anticoagulant, inhibits arterial thrombosis without impairing haemostasis[*]

Daniella M. Mizurini
1   Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
,
Ivo M. B. Francischetti
2   Section of Vector Biology, Laboratory of Malaria and Vector Research, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
,
John F. Andersen
2   Section of Vector Biology, Laboratory of Malaria and Vector Research, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
,
Robson Q. Monteiro
1   Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
› Author Affiliations
Further Information

Publication History

Received: 21 March 2010

Accepted after major revision: 30 July 2010

Publication Date:
24 November 2017 (online)

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Summary

Nitrophorin 2 (NP2) is a 20 kDa lipocalin identified in the salivary gland of the blood sucking insect, Rhodnius prolixus. It functions as a potent inhibitor of the intrinsic pathway of coagulation upon binding to factor IX (FIX) or FIXa. Herein we have investigated the in vivo antithrombotic properties of NP2. Surface plasmon resonance assays demonstrated that NP2 binds to rat FIX and FIXa with high affinities (KD = 43 and 47 nM, respectively), and prolongs the aPTT without affecting the PT. In order to evaluate NP2 antithrombotic effects in vivo two distinct models of thrombosis in rats were carried out. In the rose Bengal/laser induced injury model of arterial thrombosis, NP2 increased the carotid artery occlusion time by ≈35 and ≈155%, at doses of 8 and 80 μg/kg, respectively. NP2 also inhibited thrombus formation in an arterio-venous shunt model, showing ≈60% reduction at 400 μg/kg (i.v. administration). The antithrombotic effect lasted for up to 48 hours after a single i.v. dose. Notably, effective doses of NP2 did not increase the blood loss as evaluated by tail-transection model. In conclusion, NP2 is a potent and long-lasting inhibitor of arterial thrombosis with minor effects on haemostasis. It might be regarded as a potential agent for the treatment of human cardiovascular diseases.

* This work is dedicated to Professor Jorge A. Guimarães on his 70th birthday.