2023-06-23 09:00:16
Astronauts on the ISS are more susceptible to illness. Scientists now know why: the gene expression in their white blood cells changes.
You don’t want to get sick in space. Coughing out your lungs or even throwing up in it zero gravity is definitely no fun. That’s why astronauts often go into quarantine the days before launch. Hopefully they don’t take any pathogens with them. Yet it is remarkably common for the space travelers to develop a cold, itchy skin rash or a bladder infection.
In addition, research shows that ISS visitors excrete living particles from, among other things, the Epstein-Barr-virus (cause of mononucleosis), it varicella-zostervirus (chickenpox and shingles) and the herpes-simplexvirus (known from the cold sore). So it seems strongly that space travel weakens your immune system. But how? Researchers at the University of Ottawa now think they know. They describe their results in the journal Frontiers in Immunology.
Read also:
Gene expression changes
The study involved eleven male and three female astronauts who visited the ISS for at least four and a half months between 2015 and 2019. Blood was taken from them just before launch (once), during the mission (four times), and on return (five times over the course of months).
Lead researcher Odette Laneuville and colleagues then analyzed the blood samples. They mainly looked at the DNA of the white blood cells (leukocytes). As many as 15,410 genes in the DNA of these leukocytes changed activity (called gene expression) between launch and space travel. In a large cluster (consisting of 247 genes), gene expression decreased upon arrival at the ISS, but returned to normal levels upon return to Earth. In a smaller cluster it was the other way around; these 29 genes actually became more ‘fanatical’ in the vacuum of space.
Redistribution in microgravity
Upon closer examination, the team discovered that the first cluster mainly contains immunity genes. These genes are necessary for effective control of bacteria and viruses. Due to the reduced activity, the immune system becomes weaker and the astronauts are therefore more susceptible to diseases. The genes in the second cluster are involved in cell structure and functions. The researchers do not yet know exactly what the effect of the increased activity in space is.
But what causes the gene expression of those immune genes to go down? Laneuville and colleagues suspect it has to do with conditions on the space station. The microgravity that prevails there causes a redistribution of the blood plasma and lymph fluid in the body. The plasma volume is reduced by 10 to 15 percent.
Somehow these physical changes trigger a decline in the expression of the immune genes. More research is needed to figure this out, the team says. Scientists may therefore be able to develop medicines that counteract this immune suppression in astronauts. So that they can actually do their work in space fit and healthy.
Sources: Frontiers in Immunology, Frontiers press releaset
#Astronauts #sick #active #immune #genes