The astronauts should be in excellent health. It’s part of the job description. They quarantine before leaving to avoid getting sick and derailing a mission. Once airborne, they live and work in a sterile environment.
Yet when they get into space, some have viral flare-ups or break out in rashes. It’s a puzzle that has Odette Laneuvillea molecular biologist at the University of Ottawa, asking, « Why do they get infected up there? »
In a new study In Frontiers in ImmunologyLaneuville and his colleagues suggest it could be due to reduced activity of a hundred immune-related genes, which help give opportunistic infections a foothold.
Knowing what makes astronauts more vulnerable to infection could help make future space missions safer, experts say, and could improve care for those who are immunocompromised here on Earth.
Normally, Laneuville says our bodies harbor a multitude of viruses and bacteria at any given time, even when we’re feeling well.
« And because we’re healthy, we get to keep them in check and dormant, » she says. « But if we’re stressed or if there’s a dysregulation of the immune system, » then those viruses and bacteria can cause infections. Laneuville thought that perhaps something in space was triggering a change in the gene activity of immune cells in the astronauts’ blood that was allowing these opportunistic infections to emerge.
Then she and her colleagues enlisted 14 American and Canadian astronauts, all heading to the International Space Station for several months at different times. Blood samples were taken from Laneuville before and after their missions here on Earth, but also during their time in space. The 10-minute procedure on the ground required 90 minutes in orbit.
« They have to be very careful getting all their equipment out, the needles, the tubes. And they have to secure everything, » says Laneuville. « We don’t want any losses. Not even a drop of blood. Otherwise it will float in the air and contaminate everyone. »
The astronauts spun the blood and stored it in a super cold freezer until they returned to Earth, samples in tow. “I should have hired someone to process them,” she says. « But then I said, ‘No, they’re too precious. This blood is from outer space.’ He was my baby and I had to take care of him. »
University of Ottawa
All told, across multiple missions to the International Space Station, it took five years to collect all the samples. « You have to be very patient, » says Laneuville. « But it’s worth the wait. I’d wait longer if I had to. »
Here’s what that special blood revealed. Exactly one hundred immune-related genes are selected for space. It could be due to stress. But Laneuville thinks there’s another possibility: « Those genes respond to a decrease in gravitational force. »
He says that when an astronaut enters microgravity, his blood moves from his legs to his torso and head. He’s uncomfortable and drives things crazy. Their body solves the problem by reducing the fluid by up to 15%. But that now means there are too many immune cells crammed into this small amount of blood.
Laneuville thinks the drop in gene activity helps shed those extra cells. And this in turn affects how the immune system responds to pathogens.
« It’s like the body is telling them, ‘Don’t defend yourself, let your guard down,' » she says.
And this would allow viral and bacterial infections – normally kept at bay – to arise, infecting the astronauts.
But once they set foot on dry land again, the whole thing reverses as genes are reassembled and fluid levels return to normal. This reversal takes no more than a year, but for many geniuses it’s only a matter of weeks.
Along the way, the study may have something to say about those with compromised immune systems right here on Earth, says Brian Crucian, a NASA research immunologist who was not involved in the work.
« Think of a transplant patient » or someone who is elderly or under a great deal of stress. « There are many links between astronauts and Earth medicine. »
People who spend extended periods of time in Antarctica can also benefit from this research. With these individuals, « you guide them through difficult journeys in a deeply extreme environment, » says Crucian. « You put them on a base for a year, they experience 24 hours of darkness, 24 hours of daylight. And then you have almost everything except microgravity and radiation in Antarctica. »
This study is a good start, he says Jeremy Teoa biomedical engineer from NYU Abu Dhabi who was not part of the research.
As we send astronauts farther and father out — to the Moon and even Mars — experts say it will be more difficult to get them back to Earth for recovery or timely treatment.
“The ability to extradite compromised astronauts to Earth is no longer possible,” says Teo. « And so, we need to develop these new countermeasures to deal with these space travel stresses on the immune system. »