Key protein linked to severe cases of Covid-19

Insights gained from patient blood analyses could help identify those most at risk of developing critical Covid-19.

Image of chest with longs visible surrounded by coronavirus

Patients with severe forms of the disease have been found to show increased levels of a key protein in their blood.

Levels of the protein were nearly 10 times higher in those who died from Covid-19 than in healthy individuals, the study has found.

Spotting increased protein levels could help doctors to identify patients at risk in the early stages of disease and provide a target for new treatments, researchers say.

UK-wide study

A study led by Imperial College London and the Universities of Edinburgh and Liverpool, analysed blood samples from more than 500 Covid-19 patients across the UK.

The study included blood samples from people who developed different severities of Covid-19. It also included previously stored samples from patients who developed fatal swine flu in the 2009-10 outbreak and blood from healthy volunteers.

A protein, called GM-CSF, was found at higher levels in those who progressed to severe Covid-19, typically within four days of symptoms emerging, compared with samples from healthy participants or those who had died from swine flu, the study showed.

The researchers caution that the presence of GM-CSF alone in blood does not increase risk for patients, and further research would be needed to determine its use as a prognostic tool.

Several therapies that target GM-CSF are currently in clinical trials, though these have not yet been approved for use in the treatment of Covid-19.

Crucial insights

These insights into the molecular drivers of disease are crucial in improving our understanding and clinical management of Covid-19. Through world-leading collaborative clinical investigations such as ISARIC4C, we hope to inform the worldwide community of clinicians and investigators about where to look and what to target.

Professor Peter OpenshawImperial College London

By studying patients with severe Covid-19 at large scale across the UK, we're building a clearer picture of lung damage caused by Covid-19. The lungs are being damaged by the patient's own immune system, rather than directly being damaged by the virus. We can see specific signals in the immune system that might be responsible, but clinical trials are needed before there is any change to the way patients are treated.

Dr Kenneth BaillieUniversity of Edinburgh's Roslin Institute

The research is published in Science Immunology journal. The study was funded by the National Institute for Health Research and the Medical Research Centre – part of UKRI.

The work builds on more than a decade of collaborative research involving the ISARIC global research consortium, the ISARIC4C network of UK institutions and more than 200 hospitals collecting data from Covid-19 patients.

Related links

Paper in Science Immunology

Roslin Institute


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