A trip to Mars could endanger astronauts’ health – putting the mission at risk, according to new research.
Space travel alters gene expression in white blood cells – weakening the immune system.
It explains why crew members are more susceptible to infections. Astronauts on board the International Space Station (ISS) commonly suffer from skin rashes.
They also develop respiratory and non-respiratory diseases – and are known to give off more live virus particles.
Now scientists have shed light on the phenomenon – suggesting going to the Red Planet will be even more hazardous than feared.
Lead author Professor Odette Laneuville, a biologist at Ottawa University, said: “Here we show the expression of many genes related to immune functions rapidly decreases when astronauts reach space – while the opposite happens when they return to Earth after six months aboard the ISS.”
NASA’s current plans for a return journey to Mars will last much longer – approximately two years and nine months.
Astronauts will spend extended durations in microgravity, confined to a small space.
It’s more than twice the current record of 438 continuous days in space held by Russian cosmonaut Valery Polyakov.
The Canadian team studied gene expression in white blood cells, or leukocytes, in a group of 14 astronauts, including eleven men and three women.
They resided on board the ISS for between 4.5 and 6.5 months between 2015 and 2019.
Blood samples were collected on ten occasions – once pre-flight, four times in flight and five times back on Earth.
More than 15,400 genes were found to be differentially expressed. Two clusters with 247 and 29 genes respectively were identified in particular which changed in tandem along the timeline.
Those in the former were dialed down when reaching space and back up when returning to Earth, while genes in the second followed the opposite pattern.
Both mostly consisted of genes that code for proteins but with a difference. The predominant function was related to immunity for the genes in the first and to cellular structures and functions in the second.
The results suggest when someone travels to space changes in gene expression cause a rapid decrease in the strength of their immune system.
Co-author Prof Guy Trudel, also from Ottawa, said: “A weaker immunity increases the risk of infectious diseases, limiting astronauts’ ability to perform their demanding missions in space.
“If an infection or an immune-related condition was to evolve to a severe state requiring medical care, astronauts while in space would have limited access to care, medication, or evacuation.”
The data showed most genes in either cluster returned to their pre-flight level of expression within one year after return on Earth, and typically much sooner – on average, after a few weeks.
The results suggest returning astronauts run an elevated risk of infection for at least one month after landing back on Earth.
In contrast, the authors don’t yet know how long it takes before immune resistance is fully back to its pre-flight strength.
The length of this period is likely to depend on age, sex, genetic differences, and childhood exposure to pathogens.
One theory is a change in gene expression of leukocytes under microgravity is triggered by ‘fluid shift,’ where blood plasma is redistributed from the lower to the upper part of the body, including the lymphatic system.
This causes a reduction in plasma volume by between 10 percent and 15 percent within the first few days in space.
Fluid shift is known to be accompanied by large-scale physiological adaptations, apparently including altered gene expression.
Prof Laneuville said: “The next question is how to apply our findings to guide the design of countermeasures that will prevent immune suppression while in space in particular for long-duration flight.”
“The health of astronauts while in space, especially during long missions, would benefit from detecting both immune dysfunction and sub-clinical inflammation.
“Early detection provides opportunities for intervention, with the aim to prevent a progression towards severe symptoms.”
Humans have evolved to exist within Earth’s gravity (1 gravity), not in the weightlessness of space (0 g) or the microgravity of Mars (0.3 g)
The fluid shifts are also linked with space motion sickness, headaches, nausea, and blurred vision. In space, there is no gravity to pull blood into the lower part of the body.
Instead, it goes upwards. This has been dubbed “puffy head bird legs syndrome,” due to bodily fluids shifting towards the head, causing round, puffy faces, bulging neck vessels, and thin legs.
Astronauts feel dizzy and sometimes even faint when they return to Earth. Previous studies have shown it leads to structural changes in the brain.
NASA hopes to send humans to Mars by 2035. A typical trip takes seven months. Astronauts will be expected to stay more than a year before coming back, living in microgravity for nearly three years.
The study, published in the journal Frontiers in Immunology, was funded by the Canadian Space Agency.
Produced in association with SWNS Talker
Edited by Saba Fatima and Newsdesk Manager
