Scientists have discovered a process that may help explain why space travel appears to weaken astronauts’ immune systems.

When astronauts travel to space, many genes that play a role in immune function are deleted, according to a study published in the journal Frontiers in Immunology has found.

The authors also observed that when these astronauts returned to Earth, immune genes were “reactivated” and immune function was eventually restored to pre-flight strength.

There is growing evidence that astronauts are more susceptible to infections while in space. For example, those who spend long periods aboard the International Space Station (ISS) frequently suffer from conditions such as skin rashes, as well as respiratory and non-respiratory illnesses.

NASA astronaut Scott Kelly
NASA astronaut Scott Kelly works outside the International Space Station during a spacewalk on November 6, 2015. Space travel appears to weaken astronauts’ immune systems.
NASA via Getty Images

Research has also shown that astronauts tend to shed more live virus particles, which has been shown with the Epstein-Barr virus and varicella-zoster, the pathogen that causes shingles.

Findings like these indicate that space travel could weaken astronauts’ immune systems. But what is behind these observations?

In it borders study, researchers studied gene expression in the white blood cells of 14 astronauts.

The astronauts included 11 men and three women who had lived aboard the ISS for periods of around four to six months between the years 2015 and 2019.

For the research, which was carried out at the University of Ottawa and funded by the Canadian Space Agency, the scientists analyzed blood samples collected at various points before, during and after the flight.

“Then tubes of blood are sent to my laboratory at the University of Ottawa for the isolation of white blood cells and then the genetic material that we call RNA, products of gene expression,” said study author Odette Laneuville. news week.

“The RNA was then sequenced in a high-throughput sequencing facility, and the results were sent to my lab for further analysis.”

Gene expression is the process by which the instructions in our DNA are converted into a functional product, such as a protein.

Typically, only a small percentage of the genes in each cell are expressed, or “turned on,” at any given time. The rest are repressed, or turned off. The process of turning genes on and off is known as gene regulation.

Gene regulation is a key part of normal development, but gene expression in an organism can be affected by its surrounding environment. And it seems that this also applies to spaceflight.

In it borders In the study, the researchers identified a group of genes in astronauts, which code for proteins, that were suppressed while in space and “reactivated” again after they returned to Earth.

“Here we show that the expression of many genes related to immune functions decreases rapidly when astronauts arrive in space, while the opposite occurs when they return to Earth after six months aboard the ISS,” Laneuville said in a statement.

The results indicate that changes in the expression of these genes as a result of space travel may lead to a rapid weakening of astronauts’ immune systems.

“Weaker immunity increases the risk of infectious diseases that limit astronauts’ ability to perform their highly demanding work in space. If an infection or immune-related condition were to progress to a serious condition requiring medical attention, astronauts astronauts in space would have limited capacity. access to care and medication,” said Laneuville news week.

Fortunately for the astronauts, the scientists observed that most of the genes that had been affected returned to their pre-flight expression levels within a year of their return to Earth. This usually happened much sooner, after a few weeks, on average.

However, it is not yet clear how long it takes for the immune function of these astronauts to be fully restored, and it is likely that factors such as age, gender, childhood exposure to pathogens and genetic differences play a role.

The latest findings could have implications for the design of mitigation strategies that could prevent suppression of immune genes during long periods of space travel.

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