SPACE travel wreaks havoc on the human body, a new study has revealed.
A paper published May 28 in Nature Communications examined the effects of space travel on the immune system.
Researchers collected data from two men and two women who orbited Earth on the SpaceX Inspiration4 mission in 2021.
They uncovered that the immune system has gone haywire, triggering inflammatory responses and creating chaos at the cellular level.
Muscles
The team found evidence that a three-day high-altitude spaceflight induces the production of known cytokine signatures, as well as previously undocumented cytokines.
Cytokines are substances secreted by the immune system. They play critical roles in immune response and muscle regulation.
Scientists have noted that they are not typically associated with systemic inflammation, which is an immune response that affects the entire body.
Some of the cytokines were found to be exercins, a specific type of protein produced by muscle and other tissues during exercise.
Scientists decided to determine whether muscle tissue could be the source of these immunological markers.
They found significant increases in some myokines, or proteins produced by skeletal muscle cells.
The paper notes that this increase represented “a physiological response to microgravity” rather than a purely immunological response.
Non-muscle tissues did not show changes in Interleukin 6, a protein that indicates inflammation, nor in Interleukin 10, an anti-inflammatory molecule.
However, a muscle along the back of the leg called the soleus showed a significant increase in a molecule associated with muscular effort.
Additionally, the tibialis anterior muscle, located on the front of the leg, showed an increase in interleukins, which play a key role in activating immune system cells.
The greatest increase after landing was observed in the pro-inflammatory cytokine Interleukin 5, further implicating muscles as a potential source for the cytokines found in the I4 crew.
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Blood
Researchers collected blood from the Inspiration4 crew before and after the orbit trip.
The analysis revealed cell- and sex-specific responses to spaceflight.
The increases in interleukin 6, interleukin 10 and MCP-1, a pro-inflammatory molecule, were consistent with changes seen in other astronauts after long-duration missions.
Several other pro-inflammatory proteins were also significantly upregulated.
However, proteins such as fibrinogen, which is involved in the formation of blood clots, and hemoglobin, which carries oxygen through the bloodstream, did not change significantly.
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Mutations
To better understand the impact of spaceflight on different types of cells, scientists delved even deeper and examined the changes that happen at the cellular level.
One observation stood out. While other cell types remained stable in terms of mutations, the total number of mutations in B-cell receptors increased relative to pre-flight data.
These mutations are usually caused by inflammatory stimuli or exposure to antigens, substances that trigger an immune response.
Scientists also found evidence of possible upregulation of BCR signaling pathway genes immediately after flight.
Although they did not reach a conclusion, the data indicates that B cells are more active after a trip to space.
These cells produce antibodies to neutralize harmful substances and contribute to the body’s immune response.
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Cell differentiation
Cellular differentiation is the process by which young cells acquire specialized characteristics and achieve their mature function.
Scientists found that this occurred less in CD4 T and CD8 T cells.
T cells are a type of white blood cell called lymphophytes. They develop from stem cells in the bone marrow and play a key role in protecting the body against infections.
These findings reflected T cell suppression previously observed in simulated irradiation and microgravity.
Upon returning to Earththe astronauts’ serum showed higher concentrations of cytokines associated with inflammation.
The scientists simultaneously noted an increase in cytokines with anti-inflammatory activity, “which likely balances the return of inflammation to Earth.”
The researchers observed significant changes in secreted proteins related to the migration of monocytes and neutrophils, which travel to the site of injury.
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Gender differences
Previous studies have indicated that women may be more resilient than men to the stresses of space and may recover more quickly once they return to Earth.
Scientists decided to test this theory. They analyzed differentially expressed genes, or DEGs, which show different levels of activity under different conditions.
The team compared the proportion of up- and down-regulated DEGs between men and women, which showed a higher number of DEGs in men for almost all cell types.
Scientists also observed a greater number of altered gene expression pathways in men.
Scientists also observed a significant difference between men and women in interleukin 8 and fibrinogen levels.
Interleukin 8, or IL-8, plays an important role in the body’s inflammatory response by triggering the movement of a type of white blood cell to the site of injury.
Ultimately, the scientists concluded that gene activity was more disrupted in men than in women, possibly indicating that women are more resilient to the stressors of space travel.
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Implications for space travel
The researchers concluded that they found evidence of an immune response to space travel in the Inspiration4 data.
“We found that 18 cytokines/chemokines related to inflammation, aging, and muscle homeostasis changed after spaceflight,” they wrote.
And while the findings may appear to have implications for future crew selection, scientists noted that there is still a long way to go.
They noted that the sample size of four astronauts was small, although they used data from previous missions and studies to reinforce their findings.
The I4 mission “was not designed to determine the safety of spaceflight for all civilians,” the team concluded.
However, consistent cellular and molecular responses could help “narrow the targets for countermeasures and monitoring in future studies.”
What was the NASA Twins study?
The Twin Study provided a much-needed window into the effect of space travel on the human body.
NASA Twin study examined identical twin astronauts, Scott Kelly and Mark Kelly, who were in different environments for about a year. While Scott spent 340 days in space, Mark was on Earth.
Because identical twins share the same genetic makeup, they are physically very similar. This controls for other variables that could impact study results and gives scientists a way to study how the environment impacts health.
Samples taken before, during and after Scott’s trip to space showed changes in gene expression. This includes the process by which our DNA instructs cells to produce components such as proteins, which are used to build and repair tissues.
Mark experienced changes in gene expression on Earth, but not to the same extent as Scott in space.
One of the most striking discoveries was the evidence of telomere shortening. Telomeres are the ends of each DNA strand, which protect them from becoming “worn out.” Without telomeres, our chromosomes would be damaged and our cells would no longer function properly.
It turned out that Scott experienced a change in telomere length dynamics during his flight. These findings could help assess the overall health and potential long-term risks of astronauts in space.
This story originally appeared on The-sun.com read the full story
