Autoantibody Reactome Profiling Reveals Distinct Humoral Immune Signatures Induced by Simulated Microgravity, Radiation, and Combined Exposure in Mice.

Microgravity (μG) and space radiation are major environmental stressors leading to immune dysfunction in astronauts, but the mechanisms governing humoral immunity and effective interventions remain unclear. In this study, we used a high-throughput autoantigen microarray derived from the AAgAtlas 1.0 database to profile humoral immune responses in mice exposed to μG and proton irradiation. We generated 70,490 autoantibody reactivity measurements and observed combined effects of radiation and μG on humoral immunity. Specifically, 38 IgM and 57 IgG autoantibody candidates showed dose-associated changes across 0, 1 and 5 Gy proton irradiation. We further established a global autoantibody landscape for mice under μG, 1 Gy, 5 Gy and μG & 1 Gy. Autoantibody targets altered under μG were enriched for cardiovascular-associated proteins, whereas proton irradiation-associated targets were enriched for DNA repair-related proteins and co-exposure-associated targets were enriched for inflammation-related proteins, revealing distinct humoral immune recognition signatures across exposure conditions. Additionally, a glutamine-free diet (GFD) was associated with changes in autoantibody profiles and shifts in selected bone and hematological parameters toward control levels under μG and μG & 1 Gy conditions. This work provides a resource for investigating humoral immunity under space-related stress and identifies candidate autoantibody signatures and a potential role of dietary modulation that warrant further validation.