ORIGINAL RESEARCH article
Front. Physiol.
Sec. Environmental, Aviation and Space Physiology
Volume 16 - 2025 | doi: 10.3389/fphys.2025.1637834
This article is part of the Research TopicBioconvergence: A New Frontier for Understanding and Enhancing Human Adaptations to Extreme EnvironmentsView all articles
Effects of Hypoxia/Hyperoxia Exposure on Immune Function -Results from a Spacecraft-Relevant Hypobaric Chamber Study
Provisionally accepted- 1Johnson Space Center, National Aeronautics and Space Administration, Houston, United States
- 2Aegis Aerospace, Houston, United States
- 3JES Tech, Houston, United States
- 4KBR Inc, Houston, United States
- 5NASA Johnson Space Center, Houston, United States
- 6The University of Texas Medical Branch at Galveston, Galveston, United States
- 7Geocontrol Systems, Houston, United States
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Although the International Space Station provides a normoxic environment, deep space missions are expected to leverage a hypobaric, mildly hypoxic living environment to facilitate frequent extravehicular activities EVAs, aka spacewalks. Although hypoxia may be experienced terrestrially, it will be atypical for human physiology to live in hypobaric/hypoxic conditions yet frequently experience hyperoxic stress due to EVAs. It is well established that hypoxia induces dysregulation of the human immune system, in generally a sensitized/proinflammatory fashion. This is primarily evidenced from studies of individuals living at altitude. To ascertain the effect of hypoxic/hyperoxic shifts on immunity, a series of 11 day hypobaric chamber studies were conducted at the Johnson Space Center. The living environment consisted of 8.2-9.6psi/28.5-34% oxygen, and there were several simulated EVAs which were performed under hypobaric/hyperoxic conditions consisting of 4.3psi/85-95% oxygen. For the current sub-study, biosamples were collected before and after simulated EVAs to ascertain the effects of hypoxia, decompression and hyperoxic stress on immunity. The sub-study consisted of 3 chamber tests, 23 total subjects. Shifts in leukocyte distribution, function, and plasma cytokine concentrations were associated with atmospheric shifts, primarily after the hypobaric/hyperoxic EVA activities. Astronauts already experience immune system dysregulation due to microgravity, stress, and other mission influences. These data indicate that, similar to living at high altitude, altered atmosphere exposure in a pressurized vehicle environment may dysregulate human immunity which may be exacerbated by EVAs. The additive effects of hypoxia, in concert with other spaceflight mission variables, on clinical risks for astronauts must be better characterized to enable future exploration class space missions.
Keywords: Immunity, spaceflight, hypoxia, Hyperoxia, Extravehicular Activity
Received: 29 May 2025; Accepted: 01 Aug 2025.
Copyright: © 2025 Crucian, Diak, Gutierrez, Bustos-Lopez, Colorado, Young, Smith, Zwart, Oswalt, Hew, Estep, Garbino, Marshall-Goebel and Mehta. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Brian Crucian, Johnson Space Center, National Aeronautics and Space Administration, Houston, United States
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