OC 03.5 - An Integrative Biology Approach to Model the Role of the Feedback Activation of FXI by Thrombin in the Tissue Factor Pathway

Saturday, July 9, 2022

2:00 PM – 2:15 PM

Location: ICC Capital Suite Room 7&12

Presentation Format: Virtual

Co-Author(s)

Hari Hara Sudhan Lakshmanan, MS, PhD

PhD student
Oregon Health & Science University
PORTLAND, Oregon, United States
AE

Aldrich Estonilo

Student
San Jose State University
San Jose, California, United States
SR

Stephanie Reitsma

PhD
Oregon Health & Science University
Portland, Oregon, United States
AM

Alexander Melrose

Research assisant
Oregon Health & Science University
portland, Oregon, United States
TZ

Tony J. Zheng

MD/PhD Candidate
Oregon Health & Science University
Portland, Oregon, United States
JM

Jeevan Maddala

Adjunct Assistant Professor
West Virginia University
Morgantown, West Virginia, United States
DG

David Gailani, PhD

Professor
Vanderbilt University
Nashville, Tennessee, United States
PJ

Patrick Jurney

Assistant Professor
San Jose State University
San Jose, California, United States
CP

Cristina Puy

Research instructor
Oregon Health & Science University
Portland, Oregon, United States

Presenting Author(s)

OM

Owen J.T. McCarty, PhD, FAHA

Chair and Professor of Biomedical Engineering
Oregon Health & Science University
Portland, Oregon, United States

Background: Blood coagulation is a network of biochemical reactions regulated in part by the feedback activation of zymogens and inhibitors by the serine protease thrombin. While experiments using purified components enabled the discovery of each component in the reaction network, an integrative systems biology approach is required to understand the interplay between the components of the coagulation system.

Aims: Our goal is to delineate the contribution of the feedback activation of coagulation factor XI (FXI) by thrombin to the tissue factor (TF)-mediated thrombin generation through an integrative biology approach of systems-based modeling and experiments.

Methods: We improved the robustness of the existing ordinary differential equation-based model of the TF pathway of thrombin generation, the Hockin-Mann (HM) model, through integrating mathematical modeling and in vitro experiments. Thrombin generation measured in plasma using fluorogenic substrate-based assay revealed that the contribution of FXI to thrombin generation depended on the concentration of TF or activated coagulation factor X (FXa) used to initiate coagulation. Using this experimental data, we modified the kinetic parameters of the HM model and extended it to include the reaction kinetics of feedback activation of FXI by thrombin to construct the extended (ext.) HM model.

Results: Simulations of thrombin generation using the ext.HM model revealed that the contribution of FXI to the TF pathway of thrombin generation can be eliminated by the selective removal of the inhibitory function of tissue factor pathway inhibitor (TFPI), a Kunitz-type serine protease inhibitor of FXa and TF-activated coagulation factor VII (FVIIa) complex. We validated the predictions made using the ext.HM model via measuring thrombin generation in plasmas depleted of FXI in the presence of function-blocking antibodies against TFPI.

Conclusion(s): Together, our work is a demonstration of the utility of integrating computational systems biology and experiments in understanding complex biochemical reaction networks.