Antioxidants modulate induction of programmed endothelial cell death (apoptosis) by endotoxin.
OBJECTIVE
To evaluate the potential role of reactive oxygen metabolites as signals for endothelial cell apoptosis.


METHODS
A series of antioxidants were evaluated for their ability to block apoptosis in cultured porcine aortic endothelial cells in vitro.


RESULTS
Scavenging of the hydroxyl radical with the membrane-permeable scavenger dimethyl sulfoxide or blocking its generation via the Fenton reaction by the chelation of iron with o-phenanthroline blocked apoptosis, whereas the cell membrane-impermeable scavengers superoxide dismutase and catalase did not block apoptosis. Inhibition of xanthine oxidase with enzyme-inhibitory levels of allopurinol also failed to block apoptosis, whereas high levels of allopurinol, which also scavenge the hydroxyl radical in vitro, conferred protection. In each case (dimethyl sulfoxide, o-phenanthroline, and high-dose allopurinol), hydroxyl radical ablation was only effective when administered before the priming step (lipopolysaccharide) and was ineffective when administered later, prior to the activation step (heat shock).


CONCLUSIONS
These findings suggest a novel role for the hydroxyl radical as a nonlethal intracellular signal in endothelial cell apoptosis. Moreover, the results support a role for programmed cell death in the pathogenesis of multiple organ dysfunction syndrome and suggest novel strategies for prophylaxis and therapy of the most common cause of death in surgical intensive care units.
Abello
P A
PA
Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Md.
Fidler
S A
SA
Bulkley
G B
GB
Buchman
T G
TG
D000493:Allopurinol / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001011:Aorta; D017209:Apoptosis / Q000187:drug effects*; D001151:Arsenic / Q000009:adverse effects; D001312:Aurintricarboxylic Acid / Q000494:pharmacology; D002374:Catalase / Q000494:pharmacology; D002478:Cells, Cultured; D003513:Cycloheximide / Q000009:adverse effects; D004247:DNA / Q000032:analysis / Q000187:drug effects; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004720:Endonucleases / Q000037:antagonists & inhibitors; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects; D004731:Endotoxins / Q000009:adverse effects*; D005070:Evans Blue / Q000494:pharmacology; D005260:Female; D006358:Hot Temperature / Q000009:adverse effects; D007502:Iron Chelating Agents / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000009:adverse effects; D010618:Phenanthrolines / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000494:pharmacology; D013552:Swine
D000975:Antioxidants; D004731:Endotoxins; D007502:Iron Chelating Agents; D008070:Lipopolysaccharides; D010618:Phenanthrolines; D001312:Aurintricarboxylic Acid; D005070:Evans Blue; D000493:Allopurinol; D004247:DNA; D003513:Cycloheximide; D002374:Catalase; D013482:Superoxide Dismutase; D004720:Endonucleases; D001151:Arsenic; C025205:1,10-phenanthroline; D004121:Dimethyl Sulfoxide