Immune System of astronauts is likely at risk

A team of Swedish researchers has found that astronauts returning from long missions have issues with their immune system
In the image, a 3D reconstruction of a cytotoxic T-cell attacking bacteria

We are in the midst of a new era of space exploration. Missions to both the Moon and Mars are being planned. Many of these missions will launch in the coming decades, and scientists are examining how space can have a negative impact on astronauts’ bodies. The team at the Karolinska Institutet in Sweden has studied how microgravity experienced by astronauts could influence T cells of the immune system. T cells are a type of white blood cell called lymphocytes, crucial for cell-mediated immunity.

T Cells

The team’s findings could help explain why any changes to T cells that occur in space may persist on Earth. Such lasting changes could lead T cells to become less active and less effective in fighting infections, making astronauts vulnerable to the reactivation of latent viruses.

NASA is already looking to a future that includes lunar and even Martian travelers. With the Artemis 3 mission, a crew that includes the first woman and person of color is expected to head to the Moon in 2025. And future efforts, the agency says, will likely take humans to the surface of Mars as early as 2030.

“If we want astronauts to embark on safe space missions, we need to understand how their immune system is affected. We must find ways to counteract the harmful changes” said Lisa Westerberg, the study’s leader (ref.). “We can now study what happens to T cells, which are a key component of the immune system when exposed to weightlessness”.

Gene Expression Variation

Unable to conduct their experiments in space, Westerberg and the team brought “space to Earth”. Using a water bed, they induced the body to think it was in a weightless state. The technique is called “dry immersion”. Eight healthy subjects were exposed to dry immersion for a period of 3 weeks.

Researchers conducted blood analyses on these subjects at precise intervals, before the experiment, then 7, 14, and 21 days after the start of the experiment. Finally, one week after the experiment concluded. They found that the subjects’ T cells had altered in conjunction with dry immersion, changing their gene expression.

The conditions the subjects were subjected to induced a variation in active and inactive genes in these cells. The change became significant after 7 and 14 days of weightlessness. But the most extreme change occurred after 14 days. From a cellular perspective, T cells seemed to revert to an “immature” state. The cells behaved as if they had never encountered pathogens.

Future Experiments

“T cells began to resemble so-called naïve T cells, which have not yet encountered any intruders. This could mean they take longer to activate and thus become less effective in fighting tumor cells and infections” said Carlos Gallardo Dodd, co-leader of the study.

After 21 days of exposure to microgravity, however, the subjects’ T cells seemed to have adapted to weightlessness, with gene expression in the cells returning almost to normal. Seven days after the end of the experiment, the team found that some of those gene expression changes due to weightlessness reappeared.

The team of scientists will now attempt to use the missile probe platform located at the Esrange Space Center in Sweden to further examine T cells and the effects of weightlessness on their function. “Our results may pave the way for new treatments that reverse these changes in the genetic program of immune cells” Dodd concluded.

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