Astronaut Scott Kelly's immune system became overactive during his nearly yearlong stay at the International Space Station, the Washington Post reports.
As part of the NASA Twins Study, researchers sequenced the genomes of Scott Kelly and his identical twin brother Mark and collected health data from them to gauge the effect of an extended stay in space stay on Scott, as compared to Mark, who remained Earth-bound. Previously, researchers reported that being in space led to changes in DNA methylation and expression, as well as to longer telomeres.
The researchers now report that Scott Kelly's immune system kicked into high gear when he was in space, though returned to normal after he came back to Earth, the Associated Press adds. "It's almost as if the body's on high alert," Weill Cornell Medicine's Christopher Mason said, according to the Post.
Otherwise, Mason says the results, which were presented at the American Association for the Advancement of Science meeting, indicate the human body appears to adapt to conditions in space, it adds.
"On the whole it's encouraging," Craig Kundrot, who heads space life and science research for NASA, tells the AP. "There are no major new warning signs." NASA, the AP adds, is planning to launch a human mission to Mars in the 2030s.