OTTAWA, Ontario— Could a trip to Mars compromise the health of the astronauts and jeopardize their mission? New research shows that air travel changes gene expression, particularly affecting white blood cells and weakening the immune system. This finding explains why crew members, such as those on the International Space Station (ISS), are prone to infections, frequent skin rashes, and respiratory and non-respiratory illnesses.
“Here we show that the expression of many immune-related genes decreases rapidly when astronauts reach space, while the opposite occurs when they return to Earth six months after boarding the ISS,” says lead author Professor Odette Laneuville, an astrophysicist at the University. in Ottawa.
NASA’s mission to Mars is expected to last approximately two years and nine months. Astronauts spend a lot of time in microgravity, living in a small space with their companions. This length of time will double the current record of 438 consecutive days in space, held by Russian astronomer Valery Polyakov.
The research team analyzed gene expression in white blood cells, or leukocytes, from a group of 14 astronauts, including 11 men and three women. The scientists stayed on the ISS between 4.5 and 6.5 months from 2015 to 2019. Blood samples were taken 10 times – once before the flight, four times in flight, and five times after the flight.
The team found that more than 15,400 genes were differentially expressed. In particular, two groups of genes, containing 247 and 29 genes respectively, were changed chronologically. These genes mainly encode proteins related to the immune system and cell functions.
“Insufficient immunity increases the risk of infectious diseases, and reduces the ability of astronauts,” explains Professor Guy Trudel, from the University of Ottawa, in a press release. “If an illness or immune-related illness reaches the point where medical attention is needed, astronauts in space may not have access to treatment, medicine, or evacuation.”
The study found that most genes in both groups returned to their pre-departure levels within a year of returning to Earth, and often faster – within weeks. This suggests that astronauts are at risk of contracting an infection for a month after returning to Earth.
A variety of factors, including age, sex, genetic differences, and childhood exposure to pathogens, can determine how long it takes for the immune system to return to its initial defense capacity. One theory suggests that changes in leukocyte genes under microgravity are triggered by “fluid changes.” This change redistributes plasma from the lower to the upper part of the body, causing the plasma to drop by between 10 percent and 15 percent during the first few days in space.
“The next question is how we can use what we have found to lead to the creation of antibodies that can protect the immune system when it is in the air, especially for a long time,” says Prof. Laneuville. “Early detection provides an opportunity for intervention, with the aim of preventing the progression of serious symptoms.”
Humans evolved to live under Earth’s gravity (1g), not in weightless space (0g) or the microgravity of Mars (0.3g). Fluid changes are also associated with motion sickness, headaches, nausea, and blurred vision, often referred to as “puffy head bird legs syndrome.”
NASA plans to send people to Mars by 2035. A typical trip will take seven months, and astronauts are expected to stay for more than a year before returning, living in microgravity for about three years.
The research received funding from the Canadian Space Agency and is published in a journal Frontiers in Immunology.
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South West News Service writer Mark Waghorn contributed to this story.
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