Tucson, Ariz. -- Astronauts are known to have a higher risk of getting sick compared to their Earth-bound peers. The stresses that go with weightlessness, confined crew quarters, being away from family and friends and a busy work schedule - all the while not getting enough sleep - are known to wreak havoc on the immune system.
A research group led by immunobiologist Ty Lebsack at the University of Arizona has discovered that spaceflight changes the activity of genes controlling immune and stress response, perhaps leading to more sickness.
Between spaceflight affecting a crew's susceptibility to infections and previous observations of sickness-causing microbes thriving in a near-zero gravity environment, long journeys to far-away destinations such as Mars pose a big challenge to manned space missions.
"Taken together, our results hint at the possibility that an astronaut's immune system might be compromised in space," said Lebsack of the UA's department of immunobiology in the College of Medicine.
Lebsack and his colleagues focused their study on the thymus gland, the organ that serves as a "factory" and "training academy" for T-cells that are key players of the immune system. They compared gene-expression patterns in thymuses from four healthy mice that had spent 13 days aboard NASA's STS-118 Endeavor Space Shuttle to those from an equal number of control mice on the ground.
Their finding: 970 individual genes in the thymus of space-flown mice were up or down-regulated by a 1.5 fold change or greater. When these changes were averaged, 12 genes in the thymus tissue of all four space-flown mice were significantly up or down-regulated. "The altered genes we observed were found to primarily affect signaling molecules that play roles in programmed cell death and regulate how the body responds to stress," Lebsack said.
Programmed cell death plays an important role in a functioning body, for example in the dispos
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University of Arizona