How time spent in space creates an unusual impact on the immune system

Nearly a year in space has put the immune system of astronaut Scott Kelly on the alert and has altered the activity of some of his genes compared to his identical twin linked to Earth, have discovered researchers.

Scientists do not know if the changes were positive or negative, but the results of a unique study on Nasa twins raise new questions for doctors, with the space agency wishing to send people to Mars.

The double genetic tests have given scientists the first opportunity to follow details of human biology, such as how an astronaut 's genes activate and deactivate themselves differently in space. An amazing change announced at a scientific conference: Kelly's immune system was hyperactivated.

"It's as if the body reacts to this extraterrestrial environment a bit like a mysterious organism was inside you," said Christopher Mason geneticist of Weill Cornell Medicine in New York, who said contributed to the direction of the study. He said the doctors were now looking for that in other astronauts.

Since the beginning of space exploration, NASA has been studying the harmful consequences on astronauts' bodies, such as bone loss requiring physical exercise. In general, they are in space about six months at a time. Kelly, who lived on the International Space Station, spent 340 days in space and set an American record.

"I have never felt completely normal in space," Kelly said today, in an email to AP, citing habitual congestion due to changing fluids, headaches and concentration difficulties due to additional carbon dioxide and digestive disorders due to microgravity.

But this study was a unique dive into the molecular level, with former astronaut Mark Kelly, Scott's twin, on the ground for comparison purposes. The full results have not yet been published, but researchers have presented some of the findings at a meeting of the American Association for the Advancement of Science.

A number of genes related to the immune system have become hyperactive, Mason said. Mason also spotted a tip in the bloodstream of another marker that sensitized the immune system. Yet, Kelly's blood had less of another type of cell that constituted an early defense against viruses.

It is not surprising that gene activity changes in space – it responds to all kinds of stress.

"You can see the body adapt to changing its environment," Mason said.

The good news is that most things are back to normal soon after Kelly's return to Earth in March 2016. These genes related to the immune system, however, "seemed to have that memory or need to be almost in state. alert "even six months later, Mason told me.

"Overall, it's encouraging," said Craig Kundrot, who leads the research on life in space and science for NASA. "There are no major new warning signs, we are seeing changes that we did not necessarily anticipate, but we do not know if these changes matter."

NASA, who had been living in space for more than a year on four Russians, already knew that it was possible to take extended time out of the Earth, Kundrot said, adding: "We let's aim for more than anything else, we want our astronauts to do more than survive. "

The immune problems seem familiar to Jerry Linenger, an American astronaut who spent more than four months on the Russian space station Mir. He said that he was never sick in orbit, but once back on Earth, "I was probably sicker than I was in my life".

Astronauts have been exposed to the germs of their teammates, then after a week without anything new in the sterile environment of a space station, "your immune system is really not put to the test. test, "Linenger said.

– AP