Immune and microRNA differentials post-simulated deep spaceflight

Spaceflight can cause immune system dysfunction in astronauts with little understanding of immune outcomes in deep space. This study assessed immune responses in mice following simulated deep spaceflight, along with retrospective data from astronauts on the International Space Station (ISS). We simulated microgravity using the hindlimb unloaded mouse model alone or in combination with the newly developed simulated galactic cosmic rays or solar particle events irradiation at NASA’s Space Radiation Laboratory. Immune differentials revealed unique immune diversity following each experimental platform, suggesting consequences for deep spaceflight. Furthermore, circulating plasma microRNA sequencing analysis revealed immune system dysregulation. An ISS astronaut cohort showed elevated inflammation during low-Earth orbit missions, which supports our simulated ground experiments. Herein, distinct circulating immune biomarkers are defined by irradiation type, coupled to simulated microgravity, which can be promising targets for countermeasure developments and programmatic queries.

LET-Dependent Low Dose and Synergistic Inhibition of Human Angiogenesis by Charged Particles: Validation of miRNAs that Drive Inhibition

Space radiation inhibits angiogenesis by two mechanisms depending on the linear energy transfer (LET). Using human 3D micro-vessel models, blockage of the early motile stage of angiogenesis was determined to occur after exposure to low LET ions (<3 KeV/AMU), whereas inhibition of the later stages occurs after exposure to high LET ions (>8 KeV/AMU). Strikingly, the combined effect is synergistic, detectible as low as 0.06 Gy making mixed ion space radiation more potent. Candidates for bystander transmission are microRNAs (miRNAs), and analysis on miRNA-seq data from irradiated mice shows that angiogenesis would in theory be downregulated. Further analysis of three previously identified miRNAs showed downregulation of their targets associated with angiogenesis and confirmed their involvement in angiogenesis pathways and increased health risks associated with cardiovascular disease. Finally, synthetic molecules (antagomirs) designed to inhibit the predicted miRNAs were successfully used to reverse the inhibition of angiogenesis.

Beyond Low-Earth Orbit: Characterizing Immune and microRNA Differentials following Simulated Deep Spaceflight Conditions in Mice

Spaceflight missions can cause immune system dysfunction in astronauts with little understanding of immune outcomes in deep space. This study assessed immune responses in mice following ground-based, simulated deep spaceflight conditions, compared with data from astronauts on International Space Station missions. For ground studies, we simulated microgravity using the hindlimb unloaded mouse model alone or in combination with acute simulated galactic cosmic rays or solar particle events irradiation. Immune profiling results revealed unique immune diversity following each experimental condition, suggesting each stressor results in distinct circulating immune responses, with clear consequences for deep spaceflight. Circulating plasma microRNA sequence analysis revealed involvement in immune system dysregulation. Furthermore, a large astronaut cohort showed elevated inflammation during low-Earth orbit missions, thereby supporting our simulated ground experiments in mice. Herein, circulating immune biomarkers are defined by distinct deep space irradiation types coupled to simulated microgravity and could be targets for future space health initiatives.

Circulating miRNA Spaceflight Signature Reveals Targets for Countermeasure Development

We have identified and validated a spaceflight-associated microRNA (miRNA) signature that is shared by rodents and humans in response to simulated, short-duration and long-duration spaceflight. Previous studies have identified miRNAs that regulate rodent responses to spaceflight in low-Earth orbit, and we have confirmed the expression of these proposed spaceflight-associated miRNAs in rodents reacting to simulated spaceflight conditions. Moreover, astronaut samples from the NASA Twins Study confirmed these expression signatures in miRNA sequencing, single-cell RNA sequencing (scRNA-seq), and single-cell assay for transposase accessible chromatin (scATAC-seq) data. Additionally, a subset of these miRNAs (miR-125, miR-16, and let-7a) was found to regulate vascular damage caused by simulated deep space radiation. To demonstrate the physiological relevance of key spaceflight-associated miRNAs, we utilized antagomirs to inhibit their expression and successfully rescue simulated deep-space-radiation-mediated damage in human 3D vascular constructs.