Cyclic and constant hyperoxia cause inflammation, apoptosis and cell death in human umbilical vein endothelial cells.
BACKGROUND
Perioperative high-dose oxygen (O2 ) exposure can cause hyperoxia. While the effect of constant hyperoxia on the vascular endothelium has been investigated to some extent, the impact of cyclic hyperoxia largely remains unknown. We hypothesized that cyclic hyperoxia would induce more injury than constant hyperoxia to human umbilical vein endothelial cells (HUVECs).


METHODS
HUVECs were exposed to cyclic hyperoxia (5-95% O2 ) or constant hyperoxia (95% O2 ), normoxia (21% O2 ), and hypoxia (5% O2 ). Cell growth, viability (Annexin V/propidium iodide and 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide, MTT) lactate dehydrogenase (LDH), release, cytokine (interleukin, IL and macrophage migration inhibitory factor, MIF) release, total antioxidant capacity (TAC), and superoxide dismutase activity (SOD) of cell lysate were assessed at baseline and 8, 24, and 72 h. A signal transduction pathway finder array for gene expression analysis was performed after 8 h.


RESULTS
Constant and cyclic hyperoxia-induced gradually detrimental effects on HUVECs. After 72 h, constant or cyclic hyperoxia exposure induced change in cytotoxic (LDH +12%, P = 0.026; apoptosis +121/61%, P < 0.01; alive cells -15%, P < 0.01; MTT -16/15%, P < 0.01), inflammatory (IL-6 +142/190%, P < 0.01; IL-8 +72/43%, P < 0.01; MIF +147/93%, P < 0.01), or redox-sensitive (SOD +278%, TAC-25% P < 0.01) markers. Gene expression analysis revealed that constant and cyclic hyperoxia exposure differently activates oxidative stress, nuclear factor kappa B, Notch, and peroxisome proliferator-activated receptor pathways.


CONCLUSIONS
Extreme hyperoxia exposure induces inflammation, apoptosis and cell death in HUVECs. Although our findings cannot be transferred to clinical settings, results suggest that hyperoxia exposure may cause vascular injury that could play a role in determining perioperative outcome.
Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria.|Department of Anesthesiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
J
J
Wu
Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria.
C
C
Hafner
Unit of Anaesthesiology and Perioperative Intensive Care, University of Veterinary Medicine, Vienna, Austria.
J P
JP
Schramel
Department of Internal Medicine II, Medical University Vienna, Vienna, Austria.|Core Facilities, Medical University of Vienna, Vienna, Austria.
C
C
Kaun
Department of Internal Medicine II, Medical University Vienna, Vienna, Austria.|Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria.
K A
KA
Krychtiuk
Department of Internal Medicine II, Medical University Vienna, Vienna, Austria.|Core Facilities, Medical University of Vienna, Vienna, Austria.|Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria.
J
J
Wojta
Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria.
S
S
Boehme
Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria.
R
R
Ullrich
Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria.
E V
EV
Tretter
Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria.
K
K
Markstaller
Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Vienna, Austria.
K U
KU
Klein
D017209:Apoptosis; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D061307:Human Umbilical Vein Endothelial Cells / Q000473:pathology; D006801:Humans; D018496:Hyperoxia / Q000150:complications* / Q000473:pathology; D007249:Inflammation / Q000209:etiology*; D059467:Transcriptome