PB0862 - Targeting Neutrophil Extracellular Trap Formation under Flow in Patients with Immune Thrombotic Thrombocytopenic Purpura

Monday, June 24, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

Noritaka Yada, MD, PhD

Assistant Professor
University of Kansas Medical Center
Kansas City, Kansas, United States

Co-Author(s)

Quan Zhang, MD

Fellow
The University of Kansas Medical Center
Kansas City, Kansas, United States
AB

Antonia Biggnotti

Research Technician
University of Kansas Medical Center
Kansas City, Kansas, United States
SG

Sarah Gralnek

Research Technician
University of Kansas Medical Center
Kansas City, Kansas, United States
DS

Dennis Sosnovske

Assistant Professor
University of Kansas Medical Center
Kansas City, Kansas, United States
KH

Keenan Hogan

Assistant Professor
University of Kansas Medical Center
Kansas City, Kansas, United States
ZY

Zhan Ye

Associate Professor
University of Kansas Medical Center
Kansas City, Kansas, United States
Liang Zheng, PhD

Assistant Professor
University of Kansas Medical Center
Kansas City, Kansas, United States
Long Zheng, MD, PhD

Professor and Chair
University of Kansas Medical Center
Kansas City, Kansas, United States

Background: Neutrophil NETosis is a unique form of cell death, characterized by release of decondensed chromatin and anti-microbial contents to the extracellular space, involved in infection, inflammation, and thrombosis. However, the role of NETosis in pathogenesis of immune thrombotic thrombocytopenic purpura (iTTP) and how a targeted therapy affects the formation of neutrophil extracellular traps (NETs) remain unknown.

Aims: To determine the NETosis in vivo and ex vivo, and the role of recombinant ADAMTS13 and caplacizumab in prevention of NET formation under flow.

Methods: TTP patients, mouse model, microfluidic system are all utilized to address this question.

Results: Using flow cytometry and microfluidic assays, we demonstrate that the percentage of neutrophils undergoing NETosis (i.e., H3Cit+MPO+) in whole blood samples from iTTP patients on admission is significantly increased with a concurrent decrease in NETosis reserve inducible by Shiga toxin. Following therapy, the percentage of H3Cit+MPO+ neutrophils is significantly reduced with an improvement of NETosis reserve in these patients (Figure 1). Additionally, little to no NET and thrombus formation under flow is detected in whole blood from iTTP patients when platelet counts are very low, and the NET and thrombus formation is dramatically enhanced following therapy when platelet count rises to about 50x10^9/L or platelet counts are restored to normal with donor platelets. Similarly, no thrombus and NET formation under flow in the whole blood from vwf-/- mice but significantly enhanced in Adamts13-/- mice. Finally, recombinant ADAMTS13 or caplacizumab or anfibatide prevents the NET and thrombus formation under flow in the whole blood from iTTP patients (Figure 2) and Adamts13-/- mice.

Conclusion(s): These results indicate that NETosis and NET formation, which depends on platelets and VWF, may play a role in pathogenesis of iTTP, and a targeted therapy such as recombinant ADAMTS13 or caplacizumab may prevent the formation of NETs and thrombi under arterial flow.