Space travel would lead to a change in the gene expression of white blood cells.
- In space, many genes in white blood cells have declined, increasing the risk of infectious diseases.
- Most immunity-related genes returned to their original level of expression within weeks or a year of returning to Earth.
- Changes in leukocyte gene expression would be triggered by the movement of body fluids.
When astronauts are in space, they seem to be more susceptible to infections. Several researchers have suggested that space travel could weaken the immune system. But what is the phenomenon that can cause this deficit? This is the question that scientists from the University of Ottawa wanted to answer in a study.
As part of the work, they took blood samples from 14 astronauts, who stayed aboard the International Space Station between 4.5 and 6.5 months between 2015 and 2019, before the flight, four times during the trip. and five times upon their return to Earth. From 4 milliliters of blood taken, they isolated leukocytes, namely white blood cells, which play an essential role in the immune response.
247 genes linked to immunity have rapidly declined in space
According to research, published in Frontiers in Immunology, 276 genes, the expression of which changed throughout the period studied, were identified. In detail, 247 genes were reduced upon arrival in space and increased upon return to Earth. For the other 29 genes, the reverse pattern was observed. “Their predominant function was related to immunity for the genes of the first group, and to cellular structures and functions for the second”, say the researchers in a statement. Faced with these results, the team suggested that these changes in gene expression led to a rapid decrease in the strength of his immune system.
“Weakened immunity increases the risk of infectious diseases, which limits astronauts’ ability to perform their demanding missions in space. Should an infection or immune disorder progress to a serious condition requiring medical attention, astronauts will not would only have limited access to care, medicine or evacuation while in space”, said Dr. Guy Trudel, author of the work.
After returning to Earth, the genes returned to their usual level of expression
According to the authors, most of the genes returned to their original level of expression within weeks or a year of their return to Earth. Clearly, astronauts returning to Earth would be at high risk of infection for at least a month after landing. However, at this time, researchers do not know how long it takes for immune resistance to regain its pre-space travel strength. “The length of this period likely depends on age, gender, genetic differences, and childhood exposure to pathogens.”
In the work, the team also studied the mechanisms that modify the gene expression of leukocytes. They speculate that these changes could be triggered by “body fluid shifting”, where blood plasma is redistributed from the lower to the upper part of the body, including the lymphatic system. This phenomenon causes a reduction in the volume of plasma of 10 to 15% during the first days spent in space. “The next question is how to apply our findings to guide the design of measures that will prevent immune system suppression in space, especially for long-duration travel,” concluded Odette Laneuville, co-author of the study.
