Publication Date
11-2-2020
Document Type
Article
Publication Title
Frontiers in Immunology
Volume
11
DOI
10.3389/fimmu.2020.564950
Abstract
A comprehensive understanding of spaceflight factors involved in immune dysfunction and the evaluation of biomarkers to assess in-flight astronaut health are essential goals for NASA. An elevated neutrophil-to-lymphocyte ratio (NLR) is a potential biomarker candidate, as leukocyte differentials are altered during spaceflight. In the reduced gravity environment of space, rodents and astronauts displayed elevated NLR and granulocyte-to-lymphocyte ratios (GLR), respectively. To simulate microgravity using two well-established ground-based models, we cultured human whole blood-leukocytes in high-aspect rotating wall vessels (HARV-RWV) and used hindlimb unloaded (HU) mice. Both HARV-RWV simulation of leukocytes and HU-exposed mice showed elevated NLR profiles comparable to spaceflight exposed samples. To assess mechanisms involved, we found the simulated microgravity HARV-RWV model resulted in an imbalance of redox processes and activation of myeloperoxidase-producing inflammatory neutrophils, while antioxidant treatment reversed these effects. In the simulated microgravity HU model, mitochondrial catalase-transgenic mice that have reduced oxidative stress responses showed reduced neutrophil counts, NLR, and a dampened release of selective inflammatory cytokines compared to wildtype HU mice, suggesting simulated microgravity induced oxidative stress responses that triggered inflammation. In brief, both spaceflight and simulated microgravity models caused elevated NLR, indicating this as a potential biomarker for future in-flight immune health monitoring.
Funding Number
NNX15AB42G
Funding Sponsor
National Aeronautics and Space Administration
Keywords
inflammation, neutrophils, NLR, oxidative stress response, simulated microgravity, spaceflight
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Department
Biological Sciences
Recommended Citation
Amber M. Paul, Siddhita D. Mhatre, Egle Cekanaviciute, Ann Sofie Schreurs, Candice G.T. Tahimic, Ruth K. Globus, Sulekha Anand, Brian E. Crucian, and Sharmila Bhattacharya. "Neutrophil-to-Lymphocyte Ratio: A Biomarker to Monitor the Immune Status of Astronauts" Frontiers in Immunology (2020). https://doi.org/10.3389/fimmu.2020.564950
Comments
This is the Version of Record and can also be read online here.