A new study analyzing the blood samples of 18 Russian cosmonauts reveals that space sends the body’s defensive immune system into overdrive.

Space is bad for your health. The lack of gravity and the constant bombardment of radiation particles makes the environment treacherous. Numerous studies have shown astronauts experiencing muscle loss, cognitive impairment, blurry eyesight and a whole host of physiological changes to their metabolism and their cardiovascular system.

Now a team of researchers working from Canada and Russia have tried to investigate the roots of these problems by probing the molecular mechanisms that drive the physiological changes.

They examined blood samples taken before and after spaceflight for 18 cosmonauts working on the International Space Station, to see how proteins in the blood plasma changed over time.

The researchers used a mass spectrometer to measure the protein concentrations in the cosmonauts’ blood 30 days before they left Earth, immediately after they returned, and again seven days later.

Only 19 of the 125 proteins studied were influenced by space flight, according to the results published in a paper in Scientific Reports. The average concentrations of the majority of the proteins were mostly unchanged after the flight.

“In summary, plasma proteins whose concentrations changed during flight included pathways related to oxidative stress, cytoskeleton, cell proliferation, glucose and lipid metabolism, cell damage and repair response, apoptosis, calcium/collagen metabolism, transport of lipoproteins, cellular functions, protein degradation, signal transduction and cell energy metabolism,” the paper said.

The protein expressions associated with the immune system were boosted in the cosmonauts’ blood after they landed back on Earth.

Evgeny Nikolaev, lead author of the paper and a physics professor at the Moscow Institute of Physics and Technology and Skoltech, said: “The results showed that in weightlessness, the immune system acts like it does when the body is infected, because the human body doesn’t know what to do and tries to turn on all possible defense systems.”

Space agencies around the world including NASA, SpaceX, Roscosmos and the European Space Agency, are planning manned missions to Mars in the 2030s. Monitoring the effects that space has on the human body will continue to be a hot topic in research.

To improve these studies in the future, Nikolaev said that “the cosmonauts will have to take blood tests while in orbit.” ®