Malfunctioning immune cell linked to long COVID

Thursday March 16th 2023

The malfunctioning behaviour of an immune cell could be linked to specific symptoms of long COVID, opening the way to treatments, British researchers have reported.

Researchers from the University of Manchester, UK, say while normally functioning monocytes travel through the blood to the lungs, where they surround and kill the virus and boosts the immune response, something changes in long-COVID.

Writing in the latest edition of the European Respiratory Journal, they say abnormal migration of monocytes corresponds to shortness of breath, a common symptom in long-COVID.

The team, which also included colleagues from Manchester University NHS Foundation Trust (MFT), Northern Care Alliance Foundation Trust (NCA), and the National Institute for Health and Care Research (NIHR) Manchester Biomedical Research Centre (BRC), also established a different migration profile alongside changes to other functions correspond to fatigue.

The study included 71 people who were hospitalised with acute COVID-19 and 142 follow-up patients who attended outpatient clinics months after they were discharged from hospital after being treated for COVID-19.

All were recruited to the study between July 2020 and January 2021.

Using blood samples, the researchers examined key monocyte migratory signatures in acute disease that persisted into convalescence up to nine months following hospital discharge.

The hospitalised patients were split into mild, moderate and severe disease groups, based on their oxygen requirements.

Healthy blood samples were also obtained from frontline workers at the University of Manchester and Manchester University NHS Foundation Trust (MFT).

When they attended an outpatient review, participants completed questionnaires that assessed whether or not they had increased levels of breathlessness and/or fatigue, and if this was new since SARS-Cov-2 infection.

They found unique monocyte profiles distinguished long-COVID patients with shortness of breath and unresolved lung injury from those with ongoing fatigue, and from asymptomatic patients.

Dr Elizabeth Mann, from the Wellcome Trust/Royal Society Sir Henry Dale Fellow at The University of Manchester’s Lydia Becker Institute, said: “There is now a wealth of evidence indicating that chronic morbidity persists in many COVID-19 patients during convalescence manifesting as long-COVID, which remains a global public health problem despite vaccination programmes and milder strains of SARS-CoV-2.

“These debilitating symptoms include extreme fatigue, shortness of breath, myalgia, brain fog, depression, fibrotic lung disease and pulmonary vascular disease and we now know this can last for many months or even years following infection.

“But treatment options for long-COVID are currently limited, since the development of targeted therapeutic strategies requires an in-depth understanding of the underlying immunological pathophysiology.

“Our work finding a link between monocyte function and specific long COVID symptoms may provide an important first step on the road to possible treatments.”

The paper Monocyte migration profiles define disease severity in acute COVID-19 and unique features of long COVID. European Respiratory Journal 16 March 2023.

Tags: Flu & Viruses | Pharmaceuticals | UK News

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