Longitudinal immune profiling reveals distinct features of COVID-19 pathogenesis (preprint)

ABSTRACT

Background The pathogenesis of COVID-19, caused by a novel strain of coronavirus (SARS-CoV-2), involves a complex host-virus interaction and is characterised by an exaggerated immune response, the specific components of which are poorly understood. Here we report the outcome of a longitudinal immune profiling study in hospitalised patients during the peak of the COVID-19 pandemic in the UK and show the relationship between immune responses and severity of the clinical presentation. Methods The Coronavirus Immune Response and Clinical Outcomes (CIRCO) study was conducted at four hospitals in Greater Manchester. Patients with SARS-CoV-2 infection, recruited as close to admission as possible, provided peripheral blood samples at enrolment and sequentially thereafter. Fresh samples were assessed for immune cells and proteins in whole blood and serum. Some samples were also stimulated for 3 hours with LPS and analysed for intracellular proteins. Results were stratified based on patient-level data including severity of symptoms and date of reported symptom onset. Findings Longitudinal analysis showed a very high neutrophil to T cell ratio and abnormal activation of monocytes in the blood, which displayed high levels of the cell cycle marker, Ki67 and low COX-2. These properties all reverted in patient with good outcome. Unexpectedly, multiple aspects of inflammation were diminished as patients progressed in severity and time, even in ITU patients not recovering. Interpretation This is the first detailed longitudinal analysis of COVID-19 patients of varying severity and outcome, revealing common features and aspects that track with severity. Patients destined for a severe outcome can be identified at admission when still displaying mild-moderate symptoms. We provide clues concerning pathogenesis that should influence clinical trials and therapeutics. Targeting pathways involved in neutrophil and monocyte release from the bone marrow should be tested in patients with COVID-19. Funding: The Kennedy Trust for Rheumatology Research, The Wellcome Trust, The Royal Society, The BBSRC, National Institute for Health Research (NIHR) Biomedical Research Centres (BRC).