Two weeks in space enough to seriously damage human immune system

By Jim Leffman via SWNS

Two weeks in space is enough to seriously damage an astronaut's immune system, leaving them vulnerable to infection, a new study reveals.

It is a problem that could seriously jeopardize future space missions to Mars and the moon.

Being weightless returns the T cells into a 'naive' state where they act as if they have never encountered infection.

Researchers from the Karolinska Institutet in Sweden found that the effect started after just one week of weightlessness with the greatest effect seen after 14 days.

It could explain why astronauts’ T cells become less active at fighting infection and can even lead to the reactivation of latent viruses in the body.

Study leader Lisa Westerberg, principal researcher and Associate Professor at the Department of Microbiology, Tumor and Cell Biology, said: "The next steps in the exploration of space are human missions to the Moon and to Mars.

"Space is an extremely hostile environment that poses threats to human health.

“If astronauts are to be able to undergo safe space missions, we need to understand how their immune systems are affected and try to find ways to counter harmful changes to it.

"We’ve now been able to investigate what happens to T cells, which are a key component of the immune system when exposed to weightless conditions.”

In the study, published in the journal Science Advances, the researchers simulated weightlessness in space using a method called dry immersion.

This involves a custom-made waterbed that tricks the body into thinking it is in a weightless state.

The researchers examined T cells in the blood of eight healthy individuals for three weeks of exposure to simulated weightlessness.

Blood analyses were performed before the experiment started, at seven, 14 and 21 days after the start and at seven days after the experiment ended.

They found that the T cells significantly changed which genes were active after seven and 14 days of weightlessness with the greatest effect seen after 14 days

Dr. Carlos Gallardo Dodd said: "The T cells began to resemble more so-called naïve T cells, which have not yet encountered any intruders.

"This could mean that they take longer to be activated and thus become less effective at fighting tumor cells and infections.

"Our results can pave the way for new treatments that reverse these changes to the immune cells’ genetic program.”

After 21 days, the T cells had “adapted” their gene expression to weightlessness so that it had almost returned to normal but analyses carried out seven days after the experiment ended showed that the cells still had some of the changes.

The researchers now plan to use Esrange Space Center's sounding rocket platform in Kiruna, Sweden, to study how T cells behave in weightless conditions and how their function is affected.