There is growing evidence that illnesses are more likely to affect astronauts. For instance, respiratory and non-respiratory illnesses, as well as skin rashes, are rather prevalent among astronauts living on the International Space Station (ISS).
Additionally, it is known that astronauts shed more active viral particles, including Epstein-Barr virus, varicella-zoster, herpes-simplex-1, and Cytomegalovirus (CMV). These findings imply that space flight may compromise our immune system. But why might the immune system be so weak?
As the lead author of a recent study published in Frontiers in Immunology, Dr. Odette Laneuville is an associate professor in the Department of Biology at the University of Ottawa. “Here we demonstrate that the activity of numerous genes related to immunity decreases rapidly if astronauts come to space, whereas the opposite occurs after they return to Earth following six months on board the ISS,” she said.
The Canadian Space Agency provided funding for the study. Three women and 11 men who were part of a cohort of 14 astronauts who spent 4.5 and 6.5 months on board the International Space Station (ISS) between 2015 and 2019 were evaluated for their gene expression in leukocytes (white blood cells). Four milliliters of blood were taken from each astronaut ten times: once before takeoff, four times during the flight, and five times after landing to isolate leukocytes.
Leukocytes showed a differential expression of 15,410 genes. The researchers found two clusters of genes among them, 247 and 29 genes, respectively, whose expression changed simultaneously across the timeline under investigation.
Genes in the first cluster were turned down when they left Earth and back up when they returned, whereas genes in the second cluster behaved oppositely. Both gene clusters were primarily composed of protein-coding genes. However, the genes in the first cluster had a predominate function linked to immunity. In contrast, the genes in the second cluster had a predominate function connected to cellular structures and functions.
According to these findings, the immune system’s potency rapidly declines in space travelers due to these alterations in gene expression. “Infectious diseases are more likely to spread when immunity is compromised, which makes it harder for astronauts to complete their difficult missions in space.
“Astronauts while in space would have limited access to care, medication, or evacuation if an infection or immune-related condition were to progress to a severe state requiring medical attention,” said Dr. Guy Trudel, a rehabilitation doctor and the investigator at the Ottawa Hospital and professor at the Department of Cellular and Molecular Medicine of the University of Ottawa.
“The next issue is how to use our results to guide the development of measures that will avert suppressing the immune system while in space, particularly for long-duration flight,” stated Laneuville.
“Detecting immunological dysfunction and subclinical inflammation would benefit astronaut health while in space, especially during lengthy missions. Early detection offers chances for intervention to stop the onset of severe symptoms.
