Assessing Immune Stability in Space: Haematological and T Cell Profiling of Astronauts During the MESSAGE Science Mission in Axiom-3 on the ISS

Microgravity presents unique challenges to human physiology, particularly the immune system, during spaceflight. T lymphocytes, key components of adaptive immunity, play a vital role in immune regulation, yet the effects of microgravity on T-cell function and gene expression remain incompletely understood. This study, conducted as part of the MESSAGE (Microgravity Associated Genetics) Science Mission in the Axiom-3 mission (https://www.nasa.gov/mission/station/research-explorer/investigation/?#id=9100). We aimed to investigate how microgravity influences immune cell responses by analysing blood samples from three astronauts between pre-flight and during their space mission on the ISS (post-launch Day 4, Day 7, and Day 10 in ISS). Hemogram analysis revealed no statistically significant differences in leukocyte, erythrocyte, haemoglobin, and haematocrit levels between pre-flight and in-flight samples, suggesting a stable haematological profile under microgravity conditions. T cell subpopulation analysis indicated fluctuations in effector memory T cells (TemEARLY and TemLATE), but these changes did not reach statistical significance. These findings suggest that, within the short duration of spaceflight, haematological and immune parameters remain largely stable, underscoring the need for further research into long-term immune adaptations in microgravity. As a next step, transcriptomic analysis will be performed to identify microgravity-associated gene candidates, and CRISPR-based knock-out of the genes in T cells will be generated to explore their functional roles in microgravity-induced immune modulation.