Countermeasures-based Improvements in Stress, Immune System Dysregulation and Latent Herpesvirus Reactivation onboard the International Space Station – Relevance for Deep Space Missions and Terrestrial Medicine

• Published in: Neuroscience and biobehavioral reviews Vol. 115; pp. 68 - 76
• Main Authors: Crucian, Brian E., Makedonas, George, Sams, Clarence F., Pierson, Duane L., Simpson, Richard, Stowe, Raymond P., Smith, Scott M., Zwart, Sara R., Krieger, Stephanie S., Rooney, Bridgette, Douglas, Grace, Downs, Meghan, Nelman-Gonzalez, Mayra, Williams, Thomas J., Mehta, Satish
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01-08-2020
• Subjects: confinement; exercise; gravity; immunity; spaceflight; Stress; viral reactivation; spaceflight; confinement; gravity; exercise; immunity; viral reactivation; Stress
• ISSN: 0149-7634; 1873-7528
• DOI: 10.1016/j.neubiorev.2020.05.007

•Orbital spaceflight induces immune alterations consisting of reductions in T, NK cell function, elevated salivary stress hormones and the persistent reactivation of latent herpesviruses.•Spaceflight immune dysregulation is likely caused by some synergy of mission associated factors, including physiological and psychological stress, radiation, microgravity.•The international Space Station initiated construction in 1998 and since core construction has been completed a variety of biomedical countermeasures have been deployed including improved aerobic and resistive exercise equipment, psychological support for crewmembers, more frequent resupply and nutritional supplementation.•Immunity has been monitored for ISS astronauts for nearly 12 years and the data reveal a significant improvement for most immune and stress parameters, largely attributed to the biomedical countermeasures which have already been deployed.
The International Space Station (ISS) has continued to evolve from an operational perspective and multiple studies have monitored both stress and the immune system of ISS astronauts. Alterations were ascribed to a potentially synergistic array of factors, including microgravity, radiation, psychological stress, and circadian misalignment. Comparing similar data across 12 years of ISS construction and operations, we report that immunity, stress, and the reactivation of latent herpesviruses have all improved in ISS astronauts. Major physiological improvements seem to have initiated approximately 2012, a period coinciding with improvements onboard ISS including cargo delivery and resupply frequency, personal communication, exercise equipment and protocols, food quality and variety, nutritional supplementation, and schedule management. We conclude that spaceflight associated immune dysregulation has been positively influenced by operational improvements and biomedical countermeasures onboard ISS. Although an operational challenge, agencies should therefore incorporate, within vehicle design limitations, these dietary, operational, and stress-relieving countermeasures into deep space mission planning. Specific countermeasures that have benefited astronauts could serve as a therapy augment for terrestrial acquired immunodeficiency patients.