The severe COVID-19 immunological profile, represented by changes in cell populations and circulating inflammatory proteins, is already partly present in older healthy individuals, suggests new research presented at the 2020 ESCMID Conference on Coronavirus Disease (ECCVID).
The fatality rate of COVID-19 increases with age, reaching more than 20% in patients over 80 years, and a hyperinflammatory profile and various dysregulated immunological processes are linked to disease severity.
"Some of these dysregulations might not be a direct result of the infection but rather an underlying profile that is permissive to a more severe form of the disease," explained study co-author Ozlem Bulut, Radboud University Medical Center, Netherlands.
Bulut and colleagues investigated a series of immune cell populations and 28 circulating inflammatory markers previously linked with COVID-19 severity in two cohorts of healthy Western European individuals: the first involving 324 people with an age range of 18-71 years, and the second including 452 people ranging 18-75 years.
"After correcting the data for the sex of the participants, we observed that many inflammatory markers and changes in cell populations linked with severe COVID-19 correlate with age in healthy individuals," said senior co-author Prof Mihai Netea, also of Radboud University Medical Center.
These parameters include increased non-classical monocyte numbers, a critical decrease in T lymphocytes, particularly the naïve subsets of CD8+ and CD4+ lymphocytes and naïve regulatory T-cells, elevated circulating levels of monocyte chemoattractant protein 1 (MCP1), osteoprotegerin (OPG), hepatocyte growth factor (HGF), and declined levels of receptor activator of nuclear factor kappa-Β ligand (RANKL/TRANCE).
IL-6, one of the major biomarkers of COVID-19 severity, also increased with age in both cohorts.
Question: What are the implications of your findings?
Bulut: “We believe our findings provide valuable information for better protection and care of high-risk individuals such as the elderly.”