Key points:
- Nasal epithelial cells (NECs) from children respond quickly to SARS-CoV-2 by increasing interferon and restricting viral replication.
- With age, anti-viral effects diminish and NECs from elderly individuals produce more virus particles and experience increased cell damage.
- The age-specific antiviral response observed in NECs may explain why younger people experience milder symptoms, while older adults show greater disease severity.
Research finds that differences in how the nasal cells of young and elderly people respond to the SARS-CoV-2 virus may explain why children experience milder COVID-19 symptoms. These findings, published in Nature Microbiology, highlight the early effects of infection on human nasal epithelial cells (NECs).
Healthy participants, including children (0-11 years), adults (30-50 years) and the elderly (over 70 years) donated cells. Researchers then cultured the cells using specialized techniques that allowed them to regrow into different types of cells found in the nose. They used single-cell RNA sequencing to identify the unique genetic networks and functions of these individual cells. After sequencing, the team identified 24 distinct epithelial cell types.
Researchers mock infected or infected cultures from each age group with SARS-CoV-2. After 3 days, they found that NECs from children responded quickly to SARS-CoV-2 by increasing interferon and restricting viral replication. Interestingly, this anti-viral effect became less pronounced with age such that NECs from elderly individuals produced more infectious virus particles and experienced increased cell shedding and damage.
The research team believes that the strong antiviral response in the NECs from children may explain why younger people typically experience milder symptoms. Conversely, the increased damage and higher viral replication in elderly NECs may be related to the greater disease severity observed in older adults.
“Our research reveals how the type of cells we have in our nose changes with age and how this affects our ability to combat SARS-CoV-2 infection,” said project lead Claire Smith, professor at University College London. “This could be crucial in developing effective anti-viral treatments tailored to different age groups, especially for the elderly who are at higher risk of severe COVID-19.”
The study results demonstrate the importance of considering age as a critical factor in research and treatment of infectious disease. As a result, the team is planning future research that considers how ageing impacts the body’s response to other viral infections.