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Reduced Gravity Contributes to Neutrophil to Lymphocyte Ratio Shifting and Promotion of the Oxidative Stress ResponseSpaceflight can cause immune system dysfunction, such as elevated white blood cells (WBC) and polymorphonuclear neutrophils (PMN), along with unchanged or reduced lymphocyte counts. A high PMN to lymphocyte ratio (NLR) can acts as a poor prognosis in cancer and a biomarker for subclinical inflammation however, the NLR has not been identified as a predictor of astronaut health during spaceflight. CBC data collected on board the International Space Station (ISS) was repurposed to determine the granulocyte to lymphocyte ratio (GLR) in humans and the NLR in rodents. The results displayed a progressive increase in GLR and NLR during spaceflight and at landing. The mechanism for increased NLR was assessed in vitro using the microgravity-analog, rotating wall vessel (RWV), with human WBCs. The results indicated that simulated microgravity led to increased GLR and NLR profiles, and production of reactive oxygen species (ROS) and myeloperoxidase (MPO). Interestingly, simulated microgravity increased the number of matured PMNs that showed impaired phagocytic function, while treatment with tert-Butyl hydroperoxide (TBHP), also reduced PMN phagocytosis. In addition, 30-days of simulated microgravity (hindlimb unloading) in mice, indicated an increased NLR and MPO gene expression, which were mitigated in mitochondrial catalase overexpressing transgenic mice, suggesting ROS scavenging is essential for maintaining homeostatic immunity. Collectively, we propose that the health status of astronauts during future short- and long-term space missions can be monitored by their NLR profile, in addition to utilizing this measurement as a tool for oxidative stress response countermeasure development to restore homeostatic immunity.
Document ID
20190033110
Acquisition Source
Ames Research Center
Document Type
Poster
Authors
Paul, Amber M. (Universities Space Research Association (USRA) Moffett Field, CA, United States)
Mhatre, Siddhita D. (KBRwyle Moffett Field, CA, United States)
Cekanaviciute, Egle (Universities Space Research Association (USRA) Moffett Field, CA, United States)
Schreurs, Ann-Sofie (Universities Space Research Association (USRA) Moffett Field, CA, United States)
Tahimic, Candice G.T. (KBRwyle Moffett Field, CA, United States)
Globus, Ruth K. (NASA Ames Research Center Moffett Field, CA, United States)
Crucian, Brian (NASA Johnson Space Center Houston, TX, United States)
Bhattacharya, Sharmila (NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
November 20, 2019
Publication Date
May 9, 2019
Subject Category
Life Sciences (General)
Report/Patent Number
ARC-E-DAA-TN67991
Meeting Information
Meeting: Annual Meeting of the American Association of Immunologists (AAI) Immunology 2019
Location: San Diego, CA
Country: United States
Start Date: May 9, 2019
End Date: May 13, 2019
Sponsors: American Association of Immunologists
Funding Number(s)
CONTRACT_GRANT: NNA16BD14C
CONTRACT_GRANT: NNH15CO48B
CONTRACT_GRANT: NNA14AB82C
Distribution Limits
Public
Copyright
Public Use Permitted.
Technical Review
External Peer Committee

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