Effects of normoxic and hypoxic exercise training on the bactericidal capacity and subsequent apoptosis of neutrophils in sedentary men
Phagocytosis and oxidative burst are essential mechanisms of innate immunity by which neutrophils eliminate invading pathogens. Afterwards, phagocytic neutrophils are dissipated by facilitating apoptosis to control inflammation. This study investigates how exercise training with or without hypoxic exposure affects the bactericidal activity and subsequent apoptosis of neutrophils following strenuous exercise. A total of 60 healthy, sedentary men were randomly divided into four groups (n = 15 in each group), who were exposed to 21% O2 [normoxic control (NC)] or 15% O2 [hypoxic control (HC)] at rest or were trained at 50% of peak work rate at 21% O2 [normoxic training (NT)] or 15% O2 [hypoxic training (HT)] for 30 min/day, 5 days/week for 4 weeks. Before the intervention, acute strenuous exercise (SE) enhanced the phagocytosis of Escherichia coli (E. coli) by neutrophils and the release of neutrophil oxidant products in response to E. coli, accompanied by increases in the expression of adhesion molecules (CD62L, CD11b, and CD11a), an opsonic receptor (FcγIIIBR), and complement receptors (C1qRp and CD5aR) on neutrophils. Subsequently, the SE facilitated caspase-3 activation and phosphatidylserine exposure in E. coli-stimulated neutrophils. Furthermore, 4 weeks of HT promoted the expressions of adhesion molecules and opsonic/complement receptors on neutrophils, and it also augmented the bactericidal and apoptotic activities of neutrophils at rest or after SE. However, NT, HC, and NC did not influence these neutrophil-related immune responses to strenuous exercise. Therefore, we conclude that the HT regimen effectively promotes the bactericidal capacity of neutrophils, and facilitates their subsequent apoptosis both at rest and following SE.
KeywordsHypoxia Exercise Neutrophil Phagocytosis Apoptosis
Acute mountain sickness
Complement receptor 1
End-tidal carbon dioxide tension
End-tidal oxygen tension
- E. coli
Fcγ receptor-type IIIB
Graded exercise test
Hank’s balanced salt solution
Hypoxic exercise training
Lymphocyte function-associated antigen-1
Nicotinamide adenine dinucleotide phosphate
Normoxic exercise training
Reactive oxygen species
The authors would like to thank the volunteers for their enthusiastic participation in the present study.
JSW was involved in conception and design of research; YCC and WYC performed experiments; YCC, WYC, and JSW analyzed data, interpreted results of experiments, prepared the Figures, and drafted the paper; JSW, YCC, and TCF edited and revised the paper; JSW, YCC, WYC, and TCF approved the final version of paper.
This work was supported by the National Science Council of Taiwan (Grant number NSC 105-2314-B-182-013-MY3), Chang Gung Medical Research Program (Grant number CMRPD3G0031), and the Healthy Aging Research Center, Chang Gung University (Grant number EMRPD1A0841).
Compliance with ethical standards
Conflict of interest
No conflicts of interest, financial, or otherwise, are declared by the authors.
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