OC 58.1 - Circulating endoglin decreases platelet aggregation and thrombus formation through interaction with the αIIbβ3 integrin

Tuesday, June 27, 2023

10:45 – 11:00 ET

Room: 515

Session Available As: On-Demand

Presenting Author(s)

Elisa Rossi, PhD (she/her/hers)

Associate Professor
Université Paris Cité, INSERM U1140, Innovative Therapies in Haemostasis, France
Paris, Ile-de-France, France

Co-Author(s)

MP

Miguel Pericacho

Associate Professor
Department of Physiology and Pharmacology, University of Salamanca, Spain
Salamanca, Castilla y Leon, Spain
AK

Alexandre KAUSKOT

Researcher INSERM
INSERM U1176, Hôpital Bicêtre
Le Kremlin-Bicêtre, Ile-de-France, France
LG

Luis Gamella-Pozuelo

Post-PhD
Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
Madrid, Madrid, Spain
ER

Etienne Reboul

Master Student
Université Paris Cité, INSERM U1140, Innovative Therapies in Haemostasis, France
Paris, Ile-de-France, France
IS

Iles Saidi

Master Student
Université Paris Cité, INSERM U1140, Innovative Therapies in Haemostasis, France
Paris, Ile-de-France, France
AL

Alexandre Leuci

PhD student
Université Paris Cité, INSERM U1140, Innovative Therapies in Haemostasis, France
Paris, Ile-de-France, France
CE

Cristina Egido-Turrion

Post-PhD
Department of Physiology and Pharmacology, University of Salamanca, Spain
Salamanca, Castilla y Leon, Spain
DE

DIVINA El Hamaoui

PhD student
Université Paris Cité, INSERM U1140, Innovative Therapies in Haemostasis, France
Paris, Ile-de-France, France
AM

Aurore Marchelli

Laboratory technician
Université Paris Cité, INSERM U1140, Innovative Therapies in Haemostasis, France
Paris, Ile-de-France, France
FF

Francisco J. Fernández

Resercher
Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC),Madrid, Spain
Madrid, Madrid, Spain
IM

Isabelle Margaill

Professor
Université Paris Cité, INSERM U1140, Innovative Therapies in Haemostasis, France
Paris, Ile-de-France, France
CV

Cristina Vega

Researcher
Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC),Madrid, Spain
Madrid, Madrid, Spain
PG

Pascale Gaussem

Professor
Université Paris Cité, INSERM U1140, Innovative Therapies in Haemostasis, France
Paris, Ile-de-France, France
SP

Samuela Pasquali

Professor
Cibles Thérapeutiques et Conception de Médicaments CiTCoM -UMR8038 CNRS, Paris, France
Paris, Ile-de-France, France
David Smadja, PhD (he/him/his)

Professor of hematology
Université Paris Cité, Ile-de-France, France
CB

Christilla Bachelot-Loza

Researcher INSERM
Université Paris Cité, INSERM U1140, Innovative Therapies in Haemostasis, France
Paris, Ile-de-France, France
CB

Carmelo Bernabeu

Professor
Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
Madrid, Madrid, Spain

Background: Increased levels of the circulating form of human endoglin (sEng) have been reported in several cardiovascular-related conditions including preeclampsia, as a consequence of a cleavage product of membrane bound endoglin, present on endothelial cells. However, the role of sEng in platelet-dependent hemostasis in vivo is unknown.

Aims: Because sEng encompasses an RGD motif involved in integrin binding, we hypothesized that sEng would be able to bind integrin αIIbβ3, therefore compromising platelet binding to fibrinogen and thrombus stability.

Methods: To address this question, in vitro washed human platelet aggregation, thrombus retraction and secretion-competition assays were performed in the presence of sEng. Surface plasmon resonance (SPR) binding and computational (docking) analyses were carried out to evaluate protein-protein interactions. Transgenic mice overexpressing human sEng (hsEng+) were used to measure bleeding/rebleeding, prothrombin time (PT), blood stream and embolus formation after FeCl3-induced injury of carotid artery.

Results: Adding sEng to human whole blood under flow conditions, a smaller thrombus size compared to controls was observed. Also, we found that sEng inhibited platelet aggregation and thrombus retraction, interfering with fibrinogen binding, but without affecting platelet activation. SPR binding studies demonstrated the specific interaction between αIIbβ3 and sEng, and molecular modelling showed a good fitting between αIIbβ3 and sEng structures involving the endoglin RGD motif, suggesting the possible formation of a highly stable αIIbβ3/sEng complex. hsEng+ mice showed increased bleeding time and number of re-bleedings compared to wild-type mice. No differences in PT were denoted between genotypes. After FeCl3 injury, the number of released emboli in hsEng+ mice was higher and the occlusion was slower compared to controls.

Conclusion(s): These results show that sEng interferes with thrombus formation and stabilization, likely via its binding to platelet αIIbβ3, demonstrating its involvement in primary hemostasis control and suggesting that sEng could be a new tool for antithrombotic therapy.

Learning Objectives:

Participants will be able to acquire new information about novel vascular roles of circulating endoglin.
Participants will be able to dicover a new possible binding of αIIbβ3 integrin
Participants will be able to visualise the binding between αIIbβ3 integrin and circulating endoglin that will reduce platelet aggregation.