Covid-19: dexamethasone, a corticosteroid that slows vascular disorders responsible for complications

Press, Research

Scientists at Inserm, Hôpital Européen Georges-Pompidou AP-HP and Université Paris Cité have shown that dexamethasone, used against severe forms of COVID-19, protects the blood vessels and helps prevent thrombotic complications. This study was published on 25 September2025 in the journal Arteriosclerosis, Thrombosis, and Vascular Biology.

 

During the COVID-19 pandemic, scientists from Inserm, Hôpital Européen Georges-Pompidou AP-HP , and Université Paris Cité have shed light on one of the key mechanisms underlying severe cases of the virus.

Their new study, published on 25 September in the journal Arteriosclerosis, Thrombosis, and Vascular Biology, reveals that dexamethasone, a corticoid used to treat the most serious forms of the disease, limits these phenomena and may explain the decline in thrombotic complications among patients treated starting in July 2020.

From the first waves of the epidemic, the research team observed that the SARS-CoV-2 did not merely attack the lungs: it also caused “endotheliopathy”, a dysfunction of the inner wall of the blood vessels that play a key role in regulating blood coagulation, leading to often fatal microthromboses.

In this study, the scientists attempted to understand the impact of different treatments for severe Covid-19 on the blood vessels and coagulation.

They monitored 375 patients with COVID-19, some in intensive care, at the Hôpital Européen Georges-Pompidou. Thanks to the analysis of blood samples and a thrombin generation test (a key enzyme in the formation of blood clots), the scientists were able to measure the impact of the virus and various treatments for its most serious forms on the blood’s ability to coagulate.

Their main discovery: dexamethasone, a corticoid whose effectiveness has been proven for patients with severe forms of COVID-19 associated with respiratory complications, significantly reduces markers of endothelial damage and thrombin production. It directly protects endothelial cells against the cytokine storm caused by the virus, while heparin (a commonly used anticoagulant) does not have this effect.

These findings reinforce the idea that vascular inflammation is at the heart of COVID-19 complications, far beyond mere lung damage. Finally, it shows that the intensity of plasma-induced coagulation anomalies in patients is strongly correlated with a risk of death.

“Our experimental model has shown that dexamethasone acts not only as a general anti-inflammatory steroid, but also as a direct protector of the vessels,” explains David Smadja, coordinator of the study.

These results shed light on the observed benefits of dexamethasone in clinical trials and support its central role in the management of severe forms of COVID-19, by limiting thrombotic drifts related to vascular involvement.

Reference

Dexamethasone Suppresses Endotheliopathy and Endothelial-Induced Coagulopathy in COVID-19
Aurélien Philippe, Romy Younan, Nicolas Gendron, Nicolas Peron, Xavier Loyer, Jeanne Rancic, Caroline Hauw-Berlemont, Paul Billoir, Bertrand Hermann, Lina Khider, Olivier Sanchez, Gilles Chatelier, Chantal M Boulanger, Jean-Luc Diehl and David M. Smadja.
Arterioscler Thromb Vasc Biol., 2025 | DOI: 10.1161/ATVBAHA.125.322774

 

Translated by MA translation students, Master’s in Language Industry and Specialised Translation, Université Paris Cité, 2026

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