OC 72.5 - Toll-Like Receptor 4-Dependent and Independent platelet-dependent thrombosis in SARS-CoV-2 Infection

Wednesday, July 13, 2022

11:15 AM – 11:30 AM

Location: ExCel Center, ICC Capital Suite Room 7&12

Presentation Format: In-Person

Presenting Author(s)

Vittoria Cammisotto, PhD

Researcher
Sapienza University of Rome
Rome, Lazio, Italy

Co-Author(s)

RC

Roberto Carnevale

Assistant Professor
Sapienza university of Rome
Rome, Lazio, Italy
SB

Simona Bartimoccia

Post-doc researcher
Sapienza university of Rome
Rome, Lazio, Italy
CN

Cristina Nocella

Researcher
Sapienza university of Rome
Rome, Lazio, Italy
MB

Marianna Bufano

PhD
Sapienza university of Rome
Rome, Lazio, Italy
VC

Valentina Castellani

PhD student
Sapienza university of Rome
Rome, Lazio, Italy
LL

Lorenzo Loffredo

Full professor
Sapienza university of Rome
Rome, Lazio, Italy
SS

Sebastiano Sciarretta

Full professor
Sapienza university of Rome
Rome, Lazio, Italy
AC

Antonio Coluccia

PhD
Sapienza university of Rome
Rome, Lazio, Italy
RS

Romano Silvestri

Full professor
Sapienza university of Rome
Rome, Lazio, Italy
GC

Giancarlo Ceccarelli

Assistant Professor
Sapienza university of Rome
Rome, Lazio, Italy
AO

Alessandra Oliva

Researcher
Sapienza university of Rome
Rome, Lazio, Italy
MV

Mario Venditti

Full professor
Sapienza university of Rome
Rome, Lazio, Italy
FP

Francesco Pugliese

Full professor
Sapienza university of Rome
Rome, Lazio, Italy
CM

Claudio Mastroianni

full professor
Sapienza University of Rome
Rome, Lazio, Italy
OT

Ombretta Turriziani

Full professor
Sapienza university of Rome
Rome, Lazio, Italy
Pasquale Pignatelli, PhD

full professor
Sapienza University
Rome, Lazio, Italy
FV

Francesco Violi

Full professor
Thrombosis and Haemostasis journal
Berlin, Berlin, Germany

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with an increased risk of venous and arterial thrombosis but the underlying mechanism if still unclear.

Aims: The study would identify a mechanism implicated in platelet activation and thrombus growth during SARS-CoV-2 infection.

Methods: We performed a cross-sectional analysis of platelet function in 30 SARS-CoV-2 and 20 healthy subjects (HS) by measuring Nox2-derived oxidative stress and thromboxane (Tx) B2 and investigated if administration of monoclonal antibodies against the Spike(S) protein of SARS-CoV-2 affects platelet activation. Furthermore, we investigated in vitro if the Spike(S) protein of SARS-CoV-2 or plasma from SARS-CoV-2 enhanced platelet activation.

Results: Ex vivo studies showed enhanced platelet Nox2-derived oxidative stress and TxB2 biosynthesis and under laminar flow platelet-dependent thrombus growth in SARS-CoV-2 compared to controls; both effects were lowered by Nox2 and Toll-like receptor 4(TLR4) inhibitors. Two hours after administration of monoclonal antibodies a significant inhibition of platelet activation was observed in SARS-CoV-2 patients compared to untreated ones. In vitro study showed that S protein functionally interacts with platelet TLR4, and a docking simulation analysis suggested that TLR4 binds to S protein via three receptor-binding domains; furthermore, in platelets from SARS-CoV-2 S protein co-immunoprecipitated with TLR4. Plasma from SARS-CoV-2 patients incubated with normal platelets enhanced platelet activation and Nox2-related oxidative stress, an effect blunted by TNF-alpha inhibitor; this effect was recapitulated by an in vitro study documenting that TNF-alpha alone promoted platelet activation and amplified the platelet response to S protein via p47phox up-regulation.

Conclusion(s): The study identifies two TLR4-dependent and independent pathways promoting platelet-dependent thrombus growth and suggests inhibition of TLR4 or p47phox as a tool to counteract thrombosis in SARS-CoV-2.