PB0769 - Factor XII promotes thromboinflammation in rat model of extracorporeal membrane oxygenation (ECMO)

Monday, June 26, 2023

18:30 – 19:30 ET

Presenting Author(s)

Joseph S. Palumbo, MD (he/him/his)

Professor of Pediatrics
University of Cincinnati and the Cincinnati Children's Hospital Medical Center
Cincinnati, Ohio, United States

Co-Author(s)

LR

Leah Rosenfeldt

Research Assistant IV
Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
Cincinnati, Ohio, United States
SH

Spencer Hogue

Research Assistant
The Heart Institute, Cincinnati Children's Hospital Medical Center
Cincinnati, Ohio, United States
RC

Rebecca Crowther

Doctoral Candidate
Immunology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, Ohio
Cincinnati, Ohio, United States
Rachel L. Cantrell

Doctoral Candidate
Immunology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, Ohio
Cincinnati, Ohio, United States
WA

William A. Abplanalp

SENIOR RESEARCH ASST
The Heart Institute,Cincinnati Children's Hospital Medical Center
Cincinnati, Ohio, United States
BG

Benjamin Gourley

Research Assistant
Cancer and Blood Disease Institute,Cincinnati Children's Hospital Medical Center
Cincinnati, Ohio, United States
MD

Mallika Desai

Student
The Heart Institute,Cincinnati Children's Hospital Medical Center
Cincinnati, Ohio, United States
WM

Wioleta M. Zelek

Research Associate
Systems Immunity Research Institute and Dementia Research Institute, Cardiff University, Cardiff, United Kingdom.
Cardiff, England, United Kingdom
BM

B. Paul Morgan

Professor of complement biology
Systems Immunity Research Institute and Dementia Research Institute, Cardiff University, Cardiff, United Kingdom.
Cardiff, England, United Kingdom
FZ

Farhan Zafar

ASSOCIATE PROFESSOR
The Heart Institute,Cincinnati Children's Hospital Medical Center and The University of Cincinnati College of Medicine
Cincinnati, Ohio, United States
DM

David Morales

INSTITUTE DIRECTOR, Professor of Pediatric Cardiothoracic Surgery
The Heart Institute, Cincinnati Children's Hospital Medical Center and The University of Cincinnati College of Medicine
Cincinnati, Ohio, United States
JT

James Tweddell

PROFESSOR of Pediatric Cardiothoracic Surgery
The Heart Institute,Cincinnati Children's Hospital Medical Center and The University of Cincinnati College of Medicine
Cincinnati, Ohio, United States
JQ

Joseph Qualls

Associate Professor
Cincinnati Children's Hospital Medical Center
Cincinnati, Ohio, United States
MK

Mousa Kharnaf

Research Associate
Cincinnati Children's Hospital Medical Center and The University of Cincinnati College of Medicine
Cincinnati, Ohio, United States

Background: Factor XII (FXII) has been linked to thrombosis in ECMO, but the role of FXII in ECMO-induced inflammatory alterations is poorly understood.

Aims: To define the role of FXII in ECMO-associated inflammatory changes.

Methods: We generated novel FXII deficient (FXII-/-) Sprague-Dawley rats carrying a premature stop codon in exon 4 of the F12 gene. Plasma from FXII-/- rats had no significant FXII activity based on a 1-stage aPTT assay. FXII Wildtype (WT) and FXII-/- rats were placed on a minimally invasive venoarterial (VA) model of ECMO for a total of 1 hour or until circuit failure.

Results: FXII-/- rats were maintained on ECMO without pharmacological anticoagulation with excellent flow throughout a 1-hour experiment. WT rats placed on ECMO without anticoagulation developed thrombotic circuit failure within 10 minutes, speaking to the antithrombotic potential of targeting FXII. To avoid circuit failure in control animals, we placed a cohort of WT and FXII-/- rats on ECMO for 1 hour with systemic argatroban (thrombin inhibitor) anticoagulation. Genetic elimination of FXII essentially eliminated ECMO-induced complement activation based on measurements of C3 activation and the membrane attack complex. We harvested and analyzed the leukocytes adherent to the oxygenators at the end of ECMO. The total number of adherent leukocytes was similar between genotypes, with the majority of the cells being macrophages. Analyses of mRNA from these leukocyte revealed multiple differentially regulated genes, including genes involved in metabolism, suggesting FXII regulates leukocyte functions in this context.

Conclusion(s): These data suggest that in the context of ECMO, FXII not only promotes thrombosis, but is a key driver of complement activation. These data also suggest that FXII alters the functions of leukocytes that contact ECMO circtuit components. Targeting FXII could potentially limit both thrombotic and inflammatory complications associated with ECMO.