Weightlessness affects health of cosmonauts at molecular level
A team of scientists from Russia and Canada has analyzed the effect of space conditions on the protein composition in blood samples of 18 Russian cosmonauts. The results indicated many significant changes in the human body caused by space flight. These changes are intended to help the body adapt and take place in all the major types of human cells, tissues, and organs. The results of the research have been published in the prestigious scientific journal Nature Scientific Reports. Skoltech and MIPT Professor Evgeny Nikolaev initiated this research, and he is a corresponding author of the study.
The effects of spaceflight on the human body have been studied actively since the mid-20th century. It is widely known that space conditions influence metabolism, thermoregulation, heart biorhythms, muscle tonus, the respiration system and other physiological aspects of the human body function. However, the molecular mechanisms which drive the physiological changes caused by space flights remain unknown.
Proteins are key players in the adaptive processes in an organism, so the scientists decided to focus on them. To gain a deeper understanding of the changes in human physiology during space travel, the research team quantified concentrations of 125 proteins in the blood plasma of 18 Russian cosmonauts who had been on long-duration missions to the International Space Station. The blood was initially taken from them 30 days prior to their flights, and again immediately after their return to Earth and finally seven days after that. This timing was chosen as it helped the scientists to identify trends in protein concentration changes and see how fast the protein concentrations returned to their normal levels prior to the flight.
Protein concentrations were measured using a mass spectrometer. This technology makes it possible to identify a particular molecule and perform a quantitative analysis of a mixture of substances (count the exact number of molecules).
As a result of the study, the scientists found proteins whose concentrations remained unchanged, as well as those whose concentrations did change, but recovered rapidly to their pre-flight levels and those whose levels recovered very slowly after the cosmonaut's return to Earth.
"For the research, we took a set of proteins – non-infectious diseases biomarkers. The results showed that in weightlessness, the immune system acts like it does when the body is infected because the human body doesn't know what to do and tries to turn on all possible defense systems. For this study, we began by using quantitative proteomics to study the cosmonauts' blood indicators, so we detected not only the presence of a protein but its amount as well. We plan to use a targeted approach in the future to detect more specific proteins responsible for the human response to space conditions. To do this, the cosmonauts will have to take blood tests while in orbit," said Professor Nikolaev.
The factors that affect the human body during spaceflight are very interesting because they are different to those that influenced human evolution on Earth. It is not known if the human body has mechanisms responsible for rapidly adapting to such major changes. The results of the study indicate that such mechanisms probably do not exist because, during space flight, these adaptations take place in all the major types of human cells, tissues, and organs. This indicates that the human body does not know what to do and is trying to do everything in its power.