Fluid shifts are main drivers for microgravity simulation-induced immune-physiological changes: findings from the VIVALDI studies

Moser, Dominique; Bareille, Marie-Pierre; Ombergen, Angelique van; Hoerl, Marion; D´Amico, Federico; Feuerecker, Matthias; Dächert, Christopher; Matzel, Sandra; Robin, Adrien; Navasiolava, Nastassia; Custaud, Marc-Antoine; Choukér, Alexander; Robin, A.; Custaud, M.-A.; Navasiolava, N.; Laurens, C.; Bergouignan, A.; Vico, L.; Chopard, A.; Traon, A. Pav-Le; Choukér, A.; Moser, D.; Green, D. A.; Tipton, Michael; Denise, P.; Normand, H.; Blanc, S.; Rosnet, E. (2026): Fluid shifts are main drivers for microgravity simulation-induced immune-physiological changes: findings from the VIVALDI studies. npj Microgravity, 12: 15. ISSN 2373-8065

Abstract

Microgravity strongly affects human physiology during spaceflight. Biological sex has not yet been sufficiently considered as a variable for spaceflight deconditioning. The VivalDI studies investigated physiological systems affected by 5-days dry immersion (DI) in females and males, with a focus on immune changes in this report. In both sexes proportions of peripheral granulocytes and NK cells were elevated during DI and T-cell numbers were reduced. Leukocyte activation and cytokine levels were moderately affected. Females showed a higher Torque-Teno-virus shedding at the end of DI. Noradrenaline concentrations increased during the study with sex-specific patterns. Hemodynamics suggest that immunological changes were caused by DI-induced fluid shifts. Moreover, male study participants’ patterns were compared to a historical data set from a 5-days head-down-tilt bed rest (HDT-BR) study. Changes in leukocyte proportions and body fluid indicators were stronger in DI versus HDT-BR. These analyses indicate that fluid shifts primarily drive intervention-related immune-physiological differences, independent of biological sex. ClinicalTrials.gov, TRN: NCT05043974 and NCT05493176.

• Dokumententyp: Artikel (Klinikum der LMU)
• Organisationseinheit (Fakultäten): 07 Medizin > Klinikum der LMU München > Klinik für Anaesthesiologie
• DFG-Fachsystematik der Wissenschaftsbereiche: Lebenswissenschaften
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 491502892