Story at a glance
- Astronauts go through multiple tests to ensure they are healthy enough to go into space.
- While in space, the microgravity conditions affect their bodies in different ways.
- An experiment on the ground suggests that microgravity may suppress the immune system by lowering the activity of some immune cells and increasing the activity of others.
Astronauts go through lengthy tests before going into space to ensure they are healthy enough. And for good reason, the microgravity conditions in space affect the body’s physiology in many ways, including inner ear disturbances, heart arrhythmia, low blood pressure and dehydration.
To investigate further how microgravity may affect the body, experts can conduct experiments on the ground that mimic space conditions. A group of researchers at University of California San Francisco and Stanford University led by one of the first women astronauts, Millie Hughes-Fulford, are focused on understanding the effects of microgravity on the immune system.
In a study published in Scientific Reports, the researchers simulated microgravity on the blood samples and then analyzed the cells. They were particularly interested in T regulatory cells, also called Tregs. These cells are triggered when an infection has passed so that the immune system can ramp down its response. This means that Tregs have an important role in regulating the immune response for all kinds of diseases.
“Early in the space program, most astronauts were young and extremely healthy, but now they tend to have much more training and are older,” said space scientist and UCSF medical student Jordan Spatz, who took the lead on the study after Hughes-Fulford’s death, in a press release. “In addition, apart from astronauts, with the commercialization of space flight there will be many more older and less healthy individuals experiencing microgravity. From a space medical perspective, we see that microgravity does a lot of bad things to the human body, and we are hoping to gain the ability to mitigate some of the effects of microgravity during space travel.”
The team found that the microgravity conditions dampened down the responses of several immune cells: Natural Killer, CD4+ and CD8+ T cells. They also found that the responses of Tregs were enhanced.
“It’s a double whammy,” said co-principal investigator Brice Gaudilliere, an associate professor in the Department of Anesthesia at Stanford University School of Medicine, in the press release. “There is a dampening of T lymphocyte immune activation responses, but also an exacerbation of immunosuppressive responses by Tregs.”
This means that the immune system could potentially be less responsive if there is an infection or pathogen circulating in the body because the cells that normally attack are less active and because Tregs are suppressing the immune response. Although this study focused on analyzing the cells individually, the researchers think this study will provide a useful framework for future research and studies for long term spaceflight.
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