Gap IM-301: Identify appropriate ground-based analogs to spaceflight-induced immune dysfunction to enable ground validation of preventive/mitigative countermeasures and derive mechanistic insights.
Last Published:  11/23/20 11:55:10 AM (Central)
Responsible Element: Human Health Countermeasures (HHC)
Status: Open
Description
Present state of knowledge: The best terrestrial analog for spaceflight-associated immune system dysregulation includes stress, isolation, and circadian misalignment over prolonged durations. While missions such as NEEMO recreate these stressors with high fidelity, the missions cap at two weeks in duration. Antarctica winterover, with real deployment, isolation, extreme environment, and year-long missions, likely represents the best terrestrial analog. NASA-ESA studies recently found that winterover in interior Antarctica, at research stations located at higher geographic elevations, is confounded by the persistent hypobaric hypoxia associated with those altitudes. Therefore, winterover at coastal Antarctic research stations (located at sea level altitude) may represent the most promising terrestrial analog for immune dysregulation. Preliminary studies have demonstrated that winterover at some coastal stations results in the shedding of herpesviruses. While other terrestrial analogs such as isolation chambers (HERA, NEK) and head-down tilt bedrest have not been shown to be appropriate analogs for the immune changes seen in spaceflight, some work may be pursued to evaluate certain permutations of these analogs (i.e. 8-12 months long isolation chamber missions, prolonged head-down tilt bedrest combined with elevated CO2 levels, etc.).

Research approach: Studies are currently underway to validate the Antarctic coastal-based Palmer Station as a suitable analog for spaceflight. Plans are underway to investigate immune responses in 8-12 month long isolation missions in the Russian NEK chamber. Immune standard measures will be used to evaluate immune responses in head-down tilt bed rest studies that incorporate additional environmental stressors such as hypoxic or hypercarbic atmospheres. 
Target for Closure
A validated terrestrial analog that can support ground testing of countermeasures prior to implementation in flight.
Mappings
Risk Risk of Adverse Health Event Due to Altered Immune Response
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