Are you more likely to catch a bad cold on a spaceship than on Earth? Microgravity has negative consequences on the human body, such as loss of bones and muscles, decrease volumevolume blood, or the disturbance of the immune systemimmune system. In fact, scientists at the University of Ottawa in Canada analyzed the immune cells of 14 astronautsastronauts (eleven men and three women) having spent about six months in the International Space StationInternational Space Station (ISS). They had their blood drawn before they left for space, several times aboard the ISS and when they returned to Earth.
” We have shown that the expression of many GenoaGenoa associated with immune function decreases rapidly when astronauts reach space, while the reverse occurs when they return to Earth after six months in the ISS “, explains Odette Laneuville, lead scientist of this study published in Frontiers of immunology.
Space alters immunity
Space travel modifies the expression of over 15,000 genes present in space White blood cellsWhite blood cells. Scientists have interested 276 of them, the vast majority of which belong to the category ” decreased and then increased which includes genes whose expression decreases during the astronauts’ stay in space, and then increases again when they return to Earth to reach normal levels after a few months. Only the expression of 29 genes follows the reverse pattern; increases when astronauts are in space and decreases when they return to Earth.
These results suggest that theimmunityimmunity it decreases rapidly when their body is in it microgravitymicrogravity. For example, scientists have observed a dramatic decrease in the CD3 marker on the surface lymphocyteslymphocytes. This receiver has the task of transmitting the warning signal of the presence of a pathogenpathogen to lymphocytes and thus triggers their activation. Fortunately, CD3 gene expression returns to normal within days of returning to Earth.
Prevent space infections
Despite everything, Canadian scientists still believe that if astronauts encountered a pathogen during a space mission, their immune system response would not be optimal. They would also be more vulnerable to infection when they return to Earth, by which time their immunity regains its full capacity – anywhere from a few weeks to a few months, depending on the individual.
All this would be triggered by a redistribution of plasma in the body in conditions of microgravity. It loses between 10 and 15% of its volume after a few days in space and circulates more in the upper body. Scientists are considering prophylaxis to limit these immune problems during future human space travel. A little wool probably won’t be enough to protect you from the space chill.
Article published June 11, 2021 by Julie Kern
Microgravity is not without consequences on the human body. It could weaken future interstellar travelers in the face of disease, reducing the capacity for immunity.
On a journey through space, the human body is put to the test. Without severityseverity terrestrial, the massmass muscular astronauts melt like snow at SunSun ; they also lose bone mass, for example. Since the first long-term space stays of astronauts at the station, there has been great interest in researching the consequences of microgravity on human health. MirMir. Microgravity also upsets the balance of our immune system.
Without fully understanding its mechanisms, it has been observed that it reduces our defenses against pathogens, allowing, for example, to virusvirus to replicate faster. A recent study, published in Scientific reports, sharpen our knowledge on this topic. According to scientists at Stanford University, microgravity decreases the activity of T4 lymphocytesT4 lymphocytes and T8, but increases that of T cells regulatorsregulators.
Immune cells numb by microgravity…
Blood mononuclear cells (PBMCs) from eight volunteers were subjected to microgravity, or 1G gravity for control, for 18 hours. After this treatment, the samples were left as is or were stimulated with antigens (ConA or an anti-CD28) to elicit an immune response. The reactions of each cell have been studied thanks to the flow cytometryflow cytometry and the study of theirs mRNAmRNA.
Their results indicate that microgravity decreases responses afterward stimulationstimulationT4 lymphocytes, whose role is, among other things, to activate B lymphocytes so that they differentiate and produce antibodyantibodyT8 cells that destroy infected cells and NK cells (natural killer), effectors of innate immunity that also kill infected cells. The secretion of cytokines, moleculesmolecules that allow communication between all cells, also decreases in microgravity conditions, in particular the proinflammatory TNFα, CCL4, a molecule that attracts NK cells towards the site of infection.
…and the regulators at attention
Conversely, the expression of regulatory T cells increases in microgravity conditions. As the name suggests, they are responsible for containing the immune response from attacking itself. These cells are also involved preventionprevention Autoimmune diseases. Overactivity of regulatory T in microgravity conditions further slows down the already weak immune response after stimulation.
This is how microgravity puts our immune system to sleep. This could have serious health consequences for future travelers to other planets if, for example, a microbemicrobe infiltrates the spaceship.