A new study has just speculated a reason explaining the high mortality of Covid-19 in the elderly.
Le viruses of the Covid-19 is still not well defined. However, more and more studies from all over the world are coming to help clarify the effects of infections in different age groups and populations. In a new study published in The Lancet eBioMedicineresearchers might have discovered the reason for the high mortality of the elderly once morest SARS-CoV-2. This might, in fact, be due to a genetically predetermined limit of the immune system.
In detail, James Anderson, professor at the University of Washington (United States) who piloted the study, explains that the genetic limit would come from cell division: “When DNA divides, the terminal cap”“called telomere ““ shortens a bit. After a series of one cell replicates, it becomes too short and stops further division. All cells or all animals don’t have that limit, but human immune cells have that lifespan.”
As a reminder, the immune system produces enough cells until the age of 50. Then he becomes deficient due to telomere shortening, thus preventing them from rapidly cloning themselves. Factors directly related to DNA also come into play. Indeed, the length of telomeres depends directly on the genetic heritage of individuals.
According to the model created by James Anderson, the cell division process might thus explain why immune cells are less efficient in fighting the Covid-19 virus. In detail, this model estimates in particular that a person with an average rate of hematopoietic cells at the age of twenty would maintain a maximum capacity for clonal expansion of T cells until the sixth decade of life. Therefollowing, it would decline rapidly over the next ten years.
The authors of the study thus conclude by emphasizing that “the collapse of the capacity for clonal expansion of T cells coincides with the sharp increase in mortality due to Covid-19 with age”.
