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Effects of hyperbaric oxygen treatment on antimicrobial function and apoptosis of differentiated HL-60 (neutrophil-like) cells

Almzaiel, Anwar J., Billington, Richard, Smerdon, Gary, Moody, A. John
Life sciences 2013 v.93 no.2-3 pp. 125-131
Staphylococcus aureus, anti-infective properties, apoptosis, atmospheric pressure, breathing, caspases, hydrogen peroxide, hyperoxia, hypoxia, inflammation, models, neutrophils, normoxia, oxygen, phagocytosis, pretreatment, retinoic acid, therapeutics
AIMS: Neutrophil apoptosis is important in the resolution of inflammation in chronic wounds. Hyperbaric oxygen (HBO) therapy, an intermittent inhalation of 100% oxygen at greater than atmospheric pressure, appears to be an effective treatment for chronic wounds. The aim was to use HL-60 cells differentiated using all-trans retinoic acid (ATRA) (neutrophil-like cells) to test the hypothesis that an HBO-induced increase in antimicrobial activity might lead to an increase in apoptosis, thereby contributing to neutrophil clearance from chronic wounds. MAIN METHODS: ATRA differentiated HL-60 cells, an in vitro neutrophil model, were used to test the effects of normoxia, hypoxia (5% O₂), hyperoxia (95% O₂), hyperbaric normoxia (pressure) (8.8% O₂ at 2.4 ATA) and HBO (97.9% O₂ at 2.4 ATA) on antimicrobial function [NBT staining, superoxide and H₂O₂ production, and phagocytosis activity] and apoptosis (caspase 3/7 activity and morphological changes observed using SYBR Safe staining). KEY FINDINGS: A single 90min HBO exposure caused an increase in the respiratory burst activity of neutrophil-like cells post exposure. Phagocytosis of Staphylococcus aureus was also increased. HBO pre-treatment had a pro-apoptotic effect, increasing caspase 3/7 activity and causing morphological changes associated with apoptosis. SIGNIFICANCE: The potential detrimental effect of enhanced antimicrobial activity induced by HBO may be offset by enhanced apoptosis. Both hyperoxia and pressure alone seemed to contribute to the HBO-induced increases in antimicrobial activity and apoptosis, although there was no consistent pattern. These data contribute to explaining the effectiveness of HBO in the treatment of chronic wounds.