A new study by researchers at the Karolinska Institute in Sweden sheds light on the reduced activity and reduced efficiency of T cells in fighting infections in astronauts when they are in space – and thus in weightlessness.
As the study’s authors remind us, the next phases of space exploration will revolve around manned missions to the Moon and Mars. However, space is an extremely hostile environment that endangers human health.
One of these threats lies in the immune system changes that occur when astronauts escape gravity and persist after they return to Earth. This immune deficiency can make them more susceptible to infection and also cause dormant viruses in the body to reactivate.
“If astronauts want to conduct space missions safely, we need to understand how their immune systems are affected and try to find ways to counteract the harmful changes that occur there,” says lead author of the study, Lisa Westerberg.
“We have now been able to investigate what happens in T cells, which are essential components of the immune system, when they are exposed to weightlessness. »
As part of their work, the researchers tried to simulate the weightlessness of space using a method called dry immersion. This is a special waterbed that gives the human body the illusion that it is weightless.
The scientists therefore examined the T cells in the blood of eight healthy people after they had been exposed to this false weightlessness for three weeks. Before starting the experiment, blood tests were carried out; then seven days, two weeks and three weeks after the start of the work and finally seven days after the end of the examination.
It was found that after 7 and 14 days without gravity, T cells greatly altered their gene expression – ie which genes were active and which were not – and that the cells’ genetic program became more immature. The greatest effects were observed after 14 days.
“The T-cells started to look more like so-called naïve T-cells, meaning they haven’t encountered an intruder yet. This could mean that they would take longer to activate and would therefore be less effective at fighting the cells responsible for tumors and infections. “Our results could pave the way for new treatments that can reverse these changes in the genetic program of immune cells,” said Carlos Gallardo Dodd, also lead author of the study.
By 21 days, the T cells had “adapted” their gene expression to microgravity and were largely back to normal, but analyzes performed a week after the end of the test showed that the cells retained some of the changes.
Scientists now plan to use the facilities at Esrange, a spacecraft launch base in Sweden, to further study how T cells change when exposed to microgravity.