Microgravity in space perturbs human physiology and is detrimental for astronaut health, a fact first realized during early Apollo missions when astronauts experienced internal ear disturbances, heart arrhythmia, low BP (blood-pressure) , dehydration, and loss of calcium from their bones after their missions.
One of the foremost striking observations from Apollo missions was that just over half astronauts became sick with colds or other infections within a-week of returning to Earth. Some astronauts have even experienced re-activation of dormant viruses, like the chickenpox virus. These findings stimulated studies on the consequences of weak gravity, or “microgravity,” on the immunity system , which scientists are exploring for many years of manned rockets launches, shuttle travel and space -station stints, or sometimes by simulating space gravity in earthbound labs.
In the last study led by one among the 1st women astronauts, Millie Hughes-Fulford, Ph.D., researchers at UCSF and Stanford University now have shown that the weakening of an astronaut’s immunity system during spaceflight travel is probably going due partially to abnormal activation of immune cells called T regulator cells (Tregs).
Tregs normally are triggered to ramp down immune responses when infection not threatens and are important regulators of immune responses in diseases starting from cancer to COVID-19. In microgravity conditions, however, the researchers found changes in Tregs that prepared them to-go-to work even before the immunity-system was challenged. once they stimulated an immune-response in human immune cells from blood samples in microgravity, with a chemical often utilized in research to mimic a disease pathogen, they found that Tregs helped suppress the immunity rsponse that was triggered. This unanticipated discovery is published online June 7 within the journal Nature Scientific Reports.
Hughes-Fulford became the 1st female payload specialist to orbit Earth together with her experiments in 1991, and for many years , until her death thanks to leukemia in February, she studied the consequences of microgravity on health, first with a stress on osteoporosis and later with focuses on the immunity system . As a researcher at the San Francisco Veterans Affairs Medical center and a UCSF academician long affiliated with the Department of Medicine, Hughes-Fulford mentored aspiring space scientists, including the co-principal investigators of this latest immunology study.
Jordan Spatz, Ph.D., an area scientist and UCSF medical student who became co-PI of the study after Hughes-Fulford’s death, noted that as space-travel becomes increasingly commercialized and more common, concerns over the health status of space travelers are likely to grow.
“Early in Space program , most astronauts were young & very healthy, but now they have a tendency to possess far more training and are older,” Spatz said. “In addition, aside from astronauts, with the commercialization of space flight there’ll be more older and fewer healthy individuals experiencing microgravity. From space-medical perspective, we see that microgravity does tons of bad things to the human physical body , and that we hope to realize the power to mitigate a number of the consequences of microgravity during space-travel .”
The new study advanced earlier research led by Hughes-Fulford, confirming a number of her previous findings from experiments in space and in simulated microgravity, while contributing additional molecular discoveries. Hughes-Fulford earlier had found weaker responses from T lymphocytes of the immune system , a number of which attack specific pathogens directly and a few of which help orchestrate the immune reaction .
“It’s a double whammy,” said co-PI Brice Gaudilliere, MD, Ph.D., an professor within the Department of Anesthesia at Stanford University School of Medicine. “There may be a dampening of T lymphocyte immune activation responses, but also an exacerbation of immunosuppressive responses by Tregs.” The researchers also found that “natural killer” lymphocytes were less active under simulated microgravity, while antibody-producing B cells seemed to be unaffected.
The researchers simulated microgravity in blood samples with a specialized, cylindrical, cell-culture vessel with motor-driven rotation, long established microgravity research tool, but the process of single-cell analysis was unique. The scientists identified individual immune cells by specific type and used metal tags and spectroscopy to simultaneously detect and quantify dozens of proteins that play a task in immune function, additionally to confirming previously identified patterns of altered gene activation.
The findings were reported on Scientific Reports.