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Burtscher J, Pasha Q, Chanana N, Millet GP, Burtscher M, Strasser B. Immune consequences of exercise in hypoxia: A narrative review. JOURNAL OF SPORT AND HEALTH SCIENCE 2024; 13:297-310. [PMID: 37734549 PMCID: PMC11116970 DOI: 10.1016/j.jshs.2023.09.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/14/2023] [Accepted: 08/23/2023] [Indexed: 09/23/2023]
Abstract
Immune outcomes are key mediators of many health benefits of exercise and are determined by exercise type, dose (frequency/duration, intensity), and individual characteristics. Similarly, reduced availability of ambient oxygen (hypoxia) modulates immune functions depending on the hypoxic dose and the individual capacity to respond to hypoxia. How combined exercise and hypoxia (e.g., high-altitude training) sculpts immune responses is not well understood, although such combinations are becoming increasingly popular. Therefore, in this paper, we summarize the impact on immune responses of exercise and of hypoxia, both independently and together, with a focus on specialized cells in the innate and adaptive immune system. We review the regulation of the immune system by tissue oxygen levels and the overlapping and distinct immune responses related to exercise and hypoxia, then we discuss how they may be modulated by nutritional strategies. Mitochondrial, antioxidant, and anti-inflammatory mechanisms underlie many of the adaptations that can lead to improved cellular metabolism, resilience, and overall immune functions by regulating the survival, differentiation, activation, and migration of immune cells. This review shows that exercise and hypoxia can impair or complement/synergize with each other while regulating immune system functions. Appropriate acclimatization, training, and nutritional strategies can be used to avoid risks and tap into the synergistic potentials of the poorly studied immune consequences of exercising in a hypoxic state.
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Affiliation(s)
- Johannes Burtscher
- Institute of Sport Sciences, University of Lausanne, Lausanne 1015, Switzerland
| | - Qadar Pasha
- Institute of Hypoxia Research, New Delhi 110067, India
| | - Neha Chanana
- Department of Biochemistry, Jamia Hamdard, New Delhi 110062, India
| | - Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne 1015, Switzerland
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck 6020, Austria.
| | - Barbara Strasser
- Faculty of Medicine, Sigmund Freud Private University, Vienna 1020, Austria; Ludwig Boltzmann Institute for Rehabilitation Research, Vienna 1100, Austria
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Ducharme JB, McKenna ZJ, Specht JW, Fennel ZJ, Berkemeier QN, Deyhle MR. Divergent mechanisms regulate TLR4 expression on peripheral blood mononuclear cells following workload-matched exercise in normoxic and hypoxic environments. J Appl Physiol (1985) 2024; 136:33-42. [PMID: 37994415 DOI: 10.1152/japplphysiol.00626.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/06/2023] [Accepted: 11/19/2023] [Indexed: 11/24/2023] Open
Abstract
Exercise in hypoxia increases immune responses compared with normoxic exercise, and while Toll-like receptor 4 (TLR4) is implicated in these responses, its regulation remains undefined. The purpose of this study was to 1) investigate TLR4 regulation during workload-matched endurance exercise in normoxic and hypoxic conditions in vivo and 2) determine the independent effects of hypoxia and muscle contractions on TLR4 expression in vitro. Eight recreationally active men cycled for 1 h at 65% of their V̇o2max in normoxia (630 mmHg) and in hypobaric hypoxia (440 mmHg). Exercise in normoxia decreased TLR4 expressed on peripheral blood mononuclear cells (PBMCs), had no effect on the expression of inhibitor of κBα (IκBα), and increased the concentration of soluble TLR4 (sTLR4) in circulation. In contrast, exercise in hypoxia decreased the expression of TLR4 and IκBα in PBMCs, and sTLR4 in circulation. Markers of physiological stress were higher during exercise in hypoxia, correlating with markers of intestinal barrier damage, circulating lipopolysaccharides (LPS), and a concurrent decrease in circulating sTLR4, suggesting heightened TLR4 activation, internalization, and degradation in response to escalating physiological strain. In vitro, both hypoxia and myotube contractions independently, and in combination, reduced TLR4 expressed on C2C12 myotubes, and these effects were dependent on hypoxia-inducible factor 1 (HIF-1). In summary, the regulation of TLR4 varies depending on the physiological stress during exercise. To our knowledge, our study provides the first evidence of exercise-induced effects on sTLR4 in vivo and highlights the essential role of HIF-1 in the reduction of TLR4 during contraction and hypoxia in vitro.NEW & NOTEWORTHY We provide the first evidence of exercise affecting soluble Toll-like receptor 4 (sTLR4), a TLR4 ligand decoy receptor. We found that the degree of exercise-induced physiological stress influences TLR4 regulation on peripheral blood mononuclear cells (PBMCs). Moderate-intensity exercise reduces PBMC TLR4 and increases circulating sTLR4. Conversely, workload-matched exercise in hypoxia induces greater physiological stress, intestinal barrier damage, circulating lipopolysaccharides, and reduces both TLR4 and sTLR4, suggesting heightened TLR4 activation, internalization, and degradation under increased strain.
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Affiliation(s)
- Jeremy B Ducharme
- Department of Health, Exercise and Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
| | - Zachary J McKenna
- Department of Health, Exercise and Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
- Institute for Exercise and Environmental Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Jonathan W Specht
- Department of Health, Exercise and Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
| | - Zachary J Fennel
- Department of Health, Exercise and Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, United States
| | - Quint N Berkemeier
- Department of Health, Exercise and Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
| | - Michael R Deyhle
- Department of Health, Exercise and Sports Sciences, University of New Mexico, Albuquerque, New Mexico, United States
- Department of Cell Biology and Physiology, School of Medicine, University of New Mexico, Albuquerque, New Mexico, United States
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McKenna ZJ, Gorini Pereira F, Gillum TL, Amorim FT, Deyhle MR, Mermier CM. High altitude exposures and intestinal barrier dysfunction. Am J Physiol Regul Integr Comp Physiol 2022; 322:R192-R203. [PMID: 35043679 DOI: 10.1152/ajpregu.00270.2021] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Gastrointestinal complaints are often reported during ascents to high altitude (> 2500 m), though their etiology is not known. One potential explanation is injury to the intestinal barrier which has been implicated in the pathophysiology of several diseases. High altitude exposures can reduce splanchnic perfusion and blood oxygen levels causing hypoxic and oxidative stress. These stressors might injure the intestinal barrier leading to consequences such as bacterial translocation and local/systemic inflammatory responses. The purpose of this mini review is to 1) discuss the impact of high-altitude exposures on intestinal barrier dysfunction, and 2) present medications and dietary supplements which may have relevant impacts on the intestinal barrier during high-altitude exposures. There is a small but growing body of evidence which shows that acute exposures to high altitudes can damage the intestinal barrier. Initial data also suggests that prolonged hypoxic exposures can compromise the intestinal barrier through alterations in immunological function, microbiota, or mucosal layers. Exertion may worsen high-altitude related intestinal injury via additional reductions in splanchnic circulation and greater hypoxemia. Collectively these responses can result in increased intestinal permeability and bacterial translocation causing local and systemic inflammation. More research is needed to determine the impact of various medications and dietary supplements on the intestinal barrier during high-altitude exposures.
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Affiliation(s)
- Zachary J McKenna
- Department of Health, Exercise, and Sport Sciences, University of New Mexico, Albuquerque, NM, United States
| | - Felipe Gorini Pereira
- Department of Kinesiology, Indiana University Bloomington, Bloomington, IN, United States
| | - Trevor L Gillum
- Department of Kinesiology, California Baptist University, Riverside, CA, United States
| | - Fabiano Trigueiro Amorim
- Department of Health, Exercise, and Sport Sciences, University of New Mexico, Albuquerque, NM, United States
| | - Michael R Deyhle
- Department of Health, Exercise, and Sport Sciences, University of New Mexico, Albuquerque, NM, United States
| | - Christine M Mermier
- Department of Health, Exercise, and Sport Sciences, University of New Mexico, Albuquerque, NM, United States
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