Does spaceflight accelerate immune system aging?

Human expeditions to asteroids and Mars are potentially looming on the horizon, with programs such as Mars One even looking to establish a permanent human colony on the red planet. With the potential for long-term human space travel and habitation, researchers are working to understand the potential effects of remaining in regions with little-to-no gravity for extended periods of time.

Now, according to a study published Monday in the Journal of the Federation of American Societies for Experimental Biology, spaceflight may have detrimental effects on the immune system.

While simulating the effects of low-gravity conditions on mice, researchers found that exposure to those conditions led to the premature aging of the rodents’ immune systems. The key change was noticed in the bone marrow of the mice, which began to produce the B lymphocyte — cells that create antibodies — at levels similar to those of elderly mice.

This recent study isn’t the first of its kind to suggest a relationship between spaceflight and negative immune system effects. In August 2014, NASA released results from two collaborative investigations that looked at changes in the immune systems of 28 crew members from the International Space Station. The research found that, during spaceflight, the immune systems of crew members were “confused” — some cell functions were more depressed than normal, while other cell activity was heightened. The problem rested with the lowered function:

When cell activity is depressed, the immune system is not generating appropriate responses to threats. This may also lead to the asymptomatic viral shedding observed in some crew members, which means latent, or dormant, viruses in the body reawaken, but without symptoms of illness. When activity heightens, the immune system reacts excessively, resulting in things like increased allergy symptoms and persistent rashes, which have been reported by some crew members.

“Things like radiation, microbes, stress, microgravity, altered sleep cycles and isolation could all have an effect on crew member immune systems,” said Brian Crucian, a NASA immunology expert. “If this situation persisted for longer deep space missions, it could possibly increase risk of infection, hypersensitivity, or autoimmune issues for exploration astronauts.”

Both the FASEB and NASA studies, however, came to similar conclusions with what to do with the data: prepare. The studies state that the continued study of these immune system responses will be key to creating countermeasures to prevent these immune changes from taking place, whether in the form of drugs or in spacecraft design. In addition, the researchers believe that improved understanding about the immune system may provide benefits to people who choose to remain in Earth’s atmosphere — aiding elderly or bed-ridden people and preventing future disease in healthy adults.

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