Long-duration space flights are associated with increased levels of psychological stress, acute and chronic exposure to space radiation, and microgravity-induced changes which are known to detrimentally impact the immune system. Studies have evaluated the magnitude of immune alterations during space flight, however, due to logistical constraints unique to the space flight environment, they have either been limited to short-duration space flight missions or to basic pre- and postflight measures. The successful implementation of exploration-class missions to Mars or other near-Earth objects requires a better understanding of the impact of long-duration space flight on the immune system in order to evaluate the risks associated with immune dysregulations. In this regard, The Effects of Long-Term Exposure to Microgravity on Salivary Markers of Innate Immunity (Salivary_Markers) and Validation of Procedures for Monitoring Crewmember Immune Function (SMO 015) were conducted in order to assess immune function relating to cells of innate and adaptive immunity, as well as salivary immune parameters during a six-month mission on the International Space Station (ISS). These studies provided important data relating to innate immunity and immune cell changes during space flight, however it remains unknown whether astronauts become immunocompromised during space flight.
The main goal of this study was to characterize acute and chronic changes in polyclonal Free Light Chains (FLC), and in Immunoglobulin (Ig) class switching, indicative of a state of chronic inflammation and overall B-cell function. Investigators also assessed if changes to these sensitive biomarkers are associated with altered risk of viral reactivation and subsequent inflammation.
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Using stored plasma samples collected during the two flight studies, investigators retrospectively evaluated B-cell function and humoral immunity during and following long-duration missions. Investigators analyzed archived plasma samples from two different flight studies as well as ground-based controls. The blood samples were collected from ISS crewmembers before, during, and after space flight. Enzyme-linked immunosorbent assays (ELISAs) to determine latent viral status, Ig, and cytokine levels were also conducted to measure other indices of immune activation and suppression.
There was no effect of space flight on kappa FLC concentrations and only a marginal reduction was observed in lambda FLC levels upon return to Earth. Furthermore, IgG and IgM remained unchanged during and after space flight, when compared to pre-flight values. These results indicate that B-cell homeostasis is maintained during long-duration space flight in astronauts, advocating for potential in-flight vaccination as viable countermeasures against viral reactivation during exploration-class missions.
Spielmann, G Campbell, J Crucian, BE, Laughlin MS, and Simpson RJ. The impact of long duration spaceflight on the function of plasma cells. Medicine and Science in Sports and Exercise
. May 2018, 50(5S):336, [DOI]
Spielmann G, Agha N, Kunz H, Simpson RJ, Crucian B, Mehta S, Laughlin M, Campbell J. B cell homeostasis is maintained during long-duration spaceflight. Journal of Applied Physiology (1985).
2019. February 1; 126(2):469-476. [DOI]
Crew health and performance is critical to successful human exploration beyond low Earth orbit.
The Human Research Program (HRP) investigates and mitigates the highest risks to human health
and performance, providing essential countermeasures and technologies for human space exploration.
Risks include physiological and performance effects from hazards such as radiation, altered gravity,
and hostile environments, as well as unique challenges in medical support, human factors,
and behavioral health support. The HRP utilizes an Integrated Research Plan (IRP) to identify
the approach and research activities planned to address these risks, which are assigned to specific
Elements within the program. The Human Research Roadmap is the web-based tool for communicating the IRP content.
The Human Research Roadmap is located at: https://humanresearchroadmap.nasa.gov/
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