OC 58.2 - Absence of Protein Tyrosine Phosphatase-1 in Endothelial Cells Promotes Venous Thrombosis by Mechanisms Involving Extracellular Vesicles

Tuesday, July 12, 2022

11:00 AM – 11:15 AM

Location: ExCel Center, ICC Capital Suite Room 17

Presentation Format: In-Person

Presenting Author(s)

Konstantinos Zifkos, MSc Eng

PhD student
University Medical Center Mainz, Mainz, Germany
Mainz, Rheinland-Pfalz, Germany

Co-Author(s)

MB

Magdalena L. Bochenek, PhD

Post-Doc
Center for Thrombosis and Hemostasis, University Medical Center Mainz, Germany
Mainz, Rheinland-Pfalz, Germany
DP

Denise Pedrosa

Post-Doc
Center for Thrombosis and Hemostasis, University Medical Center Mainz, Germany
Mainz, Rheinland-Pfalz, Germany
Rajinikanth Gogiraju, PhD

Post-Doc
University Medical Center Mainz, Mainz, Germany
Mainz, Rheinland-Pfalz, Germany
SR

Stephane Robert

Engeneer
Aix Marseille University, INSERM 1263, INRAE, C2VN, Marseille, France
Marseille, Provence-Alpes-Cote d'Azur, France
Laurence Panicot-Dubois, PhD

Researcher
Aix Marseille University, INSERM 1263, INRAE, C2VN, Marseille, France
Marseille, Provence-Alpes-Cote d'Azur, France
WR

Wolfram Ruf

Scientific Director
University Medicine of the Johannes Gutenberg University Mainz, Center for Thrombosis and Hemostasis (CTH)
Mainz, Rheinland-Pfalz, Germany
PP

Philippe Poncelet

Director
Biocytex, Marseille, France
Marseille, Provence-Alpes-Cote d'Azur, France
CD

Christophe Dubois

Professor
Aix Marseille University, INSERM 1263, INRAE, C2VN, Marseille, France
Marseille, Provence-Alpes-Cote d'Azur, France
Katrin Schäfer, MD

Professor
University Medical Center Mainz, Mainz, Germany
Mainz, Rheinland-Pfalz, Germany

Background: PTP1B, a prototype protein tyrosine phosphatase, negatively regulates tyrosine kinase receptor signaling, and its absence has been associated with premature endothelial senescence. Cellular senescence and aging processes increase the risk of thrombosis, particularly in the venous system. Cellular senescence may also enhance the release of procoagulant extracellular vesicles (EVs).

Aims: To determine the contribution of endothelial PTP1B for venous thrombosis and the role of EVs therein.

Methods: Mice with tamoxifen-inducible, Tie2.ERT2-Cre mediated deletion of PTP1B (End.PTP1B-KO) underwent inferior Vena cava (IVC) ligation. Coagulation assays were performed with murine whole blood or EVs isolated from it.

Results: Serial ultrasound measurements at different time points following IVC ligation revealed that endothelial PTP1B deficiency results in significantly larger thrombi at day 2, whereas thrombus resolution over 4 weeks was not altered. Histological analysis of IVC segments supported the ultrasound findings. Activation of the coagulation cascade, both in the intrinsic and extrinsic pathway, was significantly induced by End.PTP1B-KO compared to End.PTP1B-WT control plasma. Moreover, increased factor X activation and thrombin generation were seen both using plasma and EVs isolated from End.PTP1B-KO mice. Intravital microscopy showed that PTP1B-KO EVs enhanced the recruitment of endogenous leucocytes to the site of injury to a significantly greater extent than PTP1B-WT control EVs, and this effect was less pronounced in End.PTP1B-KO mice injected with PTP1B-WT EVs. RT2 PCR profiler array analysis of primary endothelial cells revealed increased mRNA expression of markers of endothelial activation and activation-induced cell death, including annexin V and Fas receptor, in End.PTP1B-KO mice. Importantly, the procoagulant activity of PTP1B-KO EVs was diminished using antibodies neutralizing tissue factor or P-selectin glycoprotein ligand-1, whereas antibodies targeting Fas ligand had no effect.

Conclusion(s): The results of this ongoing study suggest that endothelial PTP1B deficiency promotes venous thrombosis by endothelial activation and procoagulant EV formation.