Covid-19: what is the “cytokine storm”, this phenomenon which would lead to the death of certain patients?

As Covid-19 gains ground in most countries around the world, including 8,078 deaths and 70,478 confirmed cases in France, scientists are interested in the role of “cytokine storms” in the mortality of patients with the new coronavirus. This term refers to the polypeptide molecules – in particular secreted by cells such as lymphocytes and macrophages – which are involved in the regulation of immune responses.

“A large body of data suggests that a subgroup of patients with a severe form of Covid-19 may have cytokine shock syndrome.argue researchers mostly from University College London Hospitals (UK) in a study published in the British medical journal The Lancet. This phenomenon is defined as “the excessive production of cytokines triggered by a pathogen of extreme virulence and which manifests itself in a violent inflammatory response of the immune system”. This is an inappropriate and particularly harmful response.

“An exuberant immune response is what really kills patients”

In their study, the scientists recall that respiratory failure from acute respiratory distress syndrome (ARDS) is the leading cause of death in patients with Covid-19. “Secondary hemophagocytic lymphohistiocytosis is an underrecognized hyperinflammatory syndrome characterized by a lethal, fulminant cytokine storm, with multi-organ failure”adds the team.

Interrogates by AFP, Stanley Perlman, American specialist in microbiology and immunology, also highlights the role of this phenomenon. “I think an exuberant immune response is what really kills patients [atteints du Covid-19, ndlr] destroying the tissues. But that’s not a certainty.”says the professor at the University of Iowa (United States).

Cytokine shock implicated in two other respiratory diseases

According to our colleagues at AFP, cytokine shock has already been implicated to explain the dangerousness of two other respiratory diseases induced by coronaviruses. These are SARS, which caused 774 deaths, mainly in Asia, between 2002 and 2003, and MERS (Middle East respiratory syndrome), detected for the first time in Saudi Arabia in 2012, and of which 35% of cases identified resulted in the death of the patient.

More recently, indicators from the study of 150 confirmed cases of Covid-19 in the Chinese city of Wuhan, the epicenter of the epidemic, suggest that mortality from the disease could be due to viral over-inflammation.

Existing therapeutic options

“All patients with a severe case of Covid-19 should be checked for over-inflammationwrite the researchers. We recommend the identification and treatment of over-inflammation using existing and approved treatments to address the immediate need to reduce the rising mortality rate”. Treatment options discussed include steroids, intravenous immunoglobulin, and cytokine inhibitors such as anakinra and tocilizumab.