Post-Spaceflight (STS-135) Mouse Splenocytes Demonstrate Altered Activation Properties and Surface Molecule Expression.

Space travel has been linked to an increased risk of getting sick due to the weakened immune system caused by stress. This research looked into how spaceflight affects our body's ability to fight off infections, particularly focusing on mice as a model for humans. The findings showed that after spending time in space or simulating it here on Earth (in specialized chambers), the immune cells of these "space traveler" mice became more active and changed their behavior significantly compared to regular earthbound control groups, which could explain why astronauts often get sick. The study also found that stress hormones like cortisol are higher in spaceflight-related conditions, suggesting they play a role in this immune response change. These results help us understand the health risks associated with long periods of time spent in microgravity and can guide future efforts to protect astronauts' wellbeing during their missions or even on Earth when dealing with stressful situations that might suppress our own immune system too much, leading to illnesses like colds.

In the research paper titled "Impact of Spaceflight on Immune Function," scientists investigated how space travel affects immune responses to opportunistic infections. The study focused primarily on cosmonauts and astronauts who experienced increased respiratory issues, reactivation of latent viruses (EBV, CMV, VZV), and altered host immune functions during or after space missions compared to ground controls. The methodology employed involved the use of mice models that were either exposed to microgravity conditions in flight modules aboard a Space Shuttle mission or housed within an animal enclosure module (AEM) on Earth, serving as control groups. The researchers assessed splenocyte activation and surface molecule expression by measuring mean fluorescent intensity (MFI). Key findings of the study revealed that flight mice exhibited a significant increase in percent positive cells at low to medium MFIs for various immune-related markers, such as CD25+/CD69+ T helper 1 and Th17 populations.