Abstract |
This report aims at exploring quantitatively the relationship between FXII inhibition and thromboprotection. FXII full and partial null in rats were established via zinc finger nuclease-mediated knockout and siRNA-mediated knockdown, respectively. The rats were subsequently characterized in thrombosis and hemostasis models. Knockout rats exhibited complete thromboprotection in both the arteriovenous shunt model (∼100% clot weight reduction) and the FeCl3-induced arterial thrombosis model (no reduction in blood flow), without any increase in cuticle bleeding time compared with wild-type control rats. Ex-vivo aPTT and the ellagic acid-triggered thrombin generation assay (TGA) exhibited anticoagulant changes. In contrast, ex-vivo PT or high tissue factor-triggered TGA was indistinguishable from control. Rats receiving single doses (0, 0.01, 0.03, 0.1, 0.3, 1 mg/kg) of FXII siRNA exhibited dose-dependent knockdown in liver FXII mRNA and plasma FXII protein (95 and 99%, respectively, at 1 mg/kg) at day 7 post dosing. FXII knockdown was associated with dose-dependent thromboprotection (maximal efficacy achieved with 1 mg/kg in both models) and negligible change in cuticle bleeding times. Ex-vivo TGA triggered with low-level (0.5 μmol/l) ellagic acid tracked best with the knockdown levels and efficacy. Our findings confirm and extend literature reports of an attractive benefit-to-risk profile of targeting FXII for antithrombotic therapies. Titrating of FXII is instructive for its pharmacological inhibition. The knockout rat is valuable for evaluating both mechanism-based safety concerns and off-target effects of FXII(a) inhibitors. Detailed TGA analyses will inform on optimal trigger conditions in studying pharmacodynamic effects of FXII(a) inhibition.
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Authors | Tian-Quan Cai, Weizhen Wu, Myung K Shin, Yiming Xu, Nina Jochnowitz, Yuchen Zhou, Lizbeth Hoos, Ross Bentley, Walter Strapps, Anil Thankappan, Joseph M Metzger, Martin L Ogletree, Marija Tadin-Strapps, Dietmar A Seiffert, Zhu Chen |
Journal | Blood coagulation & fibrinolysis : an international journal in haemostasis and thrombosis
(Blood Coagul Fibrinolysis)
Vol. 26
Issue 8
Pg. 893-902
(Dec 2015)
ISSN: 1473-5733 [Electronic] England |
PMID | 26192114
(Publication Type: Journal Article)
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Chemical References |
- Chlorides
- Ferric Compounds
- RNA, Messenger
- RNA, Small Interfering
- Ellagic Acid
- Factor XII
- Endodeoxyribonucleases
- Thrombin
- ferric chloride
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Topics |
- Animals
- Arteriovenous Shunt, Surgical
- Chlorides
(pharmacology)
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Ellagic Acid
(pharmacology)
- Endodeoxyribonucleases
(genetics, metabolism)
- Factor XII
(antagonists & inhibitors, genetics, metabolism)
- Ferric Compounds
(pharmacology)
- Gene Knockout Techniques
- Hemorrhage
(prevention & control)
- Humans
- Liver
(metabolism)
- Male
- Partial Thromboplastin Time
- RNA, Messenger
(genetics, metabolism)
- RNA, Small Interfering
(administration & dosage, genetics, metabolism)
- Rats
- Rats, Sprague-Dawley
- Thrombin
(metabolism)
- Thrombolytic Therapy
(methods)
- Thrombosis
(chemically induced, genetics, pathology, therapy)
- Zinc Fingers
(genetics)
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