Revised model of the tissue factor pathway of thrombin generation: Role of the feedback activation of FXI

Publication Date

6-1-2022

Document Type

Article

Publication Title

Journal of Thrombosis and Haemostasis

Volume

20

Issue

6

DOI

10.1111/jth.15716

First Page

1350

Last Page

1363

Abstract

Background: Biochemical reaction networks are self-regulated in part due to feedback activation mechanisms. The tissue factor (TF) pathway of blood coagulation is a complex reaction network controlled by multiple feedback loops that coalesce around the serine protease thrombin. Objectives: Our goal was to evaluate the relative contribution of the feedback activation of coagulation factor XI (FXI) in TF-mediated thrombin generation using a comprehensive systems-based analysis. Materials and Methods: We developed a systems biology model that improves the existing Hockin-Mann (HM) model through an integrative approach of mathematical modeling and in vitro experiments. Thrombin generation measured using in vitro assays revealed that the feedback activation of FXI contributes to the propagation of thrombin generation based on the initial concentrations of TF or activated coagulation factor X (FXa). We utilized experimental data to improve the robustness of the HM model to capture thrombin generation kinetics without a role for FXI before including the feedback activation of FXI by thrombin to construct the extended (ext.) HM model. Results and Conclusions: Using the ext.HM model, we predicted that the contribution of positive feedback of FXI activation by thrombin can be abolished by selectively eliminating the inhibitory function of tissue factor pathway inhibitor (TFPI), a serine protease inhibitor of FXa and TF-activated factor VII (FVIIa) complex. This prediction from the ext.HM model was experimentally validated using thrombin generation assays with function blocking antibodies against TFPI and plasmas depleted of FXI. Together, our results demonstrate the applications of combining experimental and modeling techniques in predicting complex biochemical reaction systems.

Funding Number

F30HL158079

Funding Sponsor

National Institutes of Health

Keywords

coagulation factor XI, feedback regulation, systems biology, thrombin, tissue factor pathway inhibitor

Department

Biomedical Engineering

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