Globallookpress Konstantin Kokoshkin,
Australian scientists have discovered why older people are especially vulnerable to infection with respiratory illnesses and viral pneumonia, including SARS-CoV-2.
And the journal Clinical & Translational Immunology indicates that the elderly are known to be susceptible to infection with viruses, and their lung infections often lead to complications and serious consequences.
Scientists hypothesize that this is related to a decline in immune system function with age. But it is not known why these functions decrease against lung pathogens in the first place.
To determine these causes, a team of researchers headed by Linda Wakim from the Peter Doherty Institute for Infection and Immunology at the University of Melbourne in Australia conducted a study using lung tissue samples from 22-68 years old, and determined the change in immune cells in the human lungs during his lifetime. The team also studied, in laboratory experiments, how immune cells respond to influenza viruses and SARS-CoV-2. For your information, none of the donors were sick before the Covid-19 study.
The results showed that while most types of immune cells remain stable throughout life, the numbers of memory T and CD8 cells (BD8) decrease with age. It turns out that tissue memory T cells, or TRM cells, a line of T cells found in the tissues of the skin, lungs, and digestive system, are particularly susceptible to immune aging.
The researchers discovered that when the lung tissue is infected with the influenza virus, a weakened immune response to the virus is observed in the elderly, which is expressed by a decrease in the production of type 1 interferons and polypeptide cytokines GM-CSF and in particular, gamma interferon, which is produced by CD8 memory cells + T.
According to the researchers, the slow immune response to the influenza virus in the elderly is due to the fact that with age, the number of T cells to fight the influenza virus decreases, and memory cells release fewer “emergency” signals about the infected cells.
As for SARS-CoV-2, the immune response was weak in all samples, regardless of age. The researchers explain this, as the emerging coronavirus is unknown to the immune system, because it has not previously encountered it, in addition to the lack of special immune cells that can fight it.
The researchers believe, that the main reason for the decrease in immunity against pneumonia in the elderly is the depletion of TRM cells to combat lung pathogens with age, which leads to a weakening of the early anti-virus immune response.
According to the researchers, these results are an important contribution to the understanding of age-related changes in the lungs and allow for a strategy to preserve tissue memory for CD8 + cells, and to improve the immunity of older people to respiratory pathogens.