The effect of intracellular antioxidant delivery (catalase) on hydrogen peroxide and proinflammatory cytokine synthesis: a new therapeutic horizon.
Reactive oxygen species synthesized by endothelial cells may be responsible for cell damage and altered physiologic function. After endotoxin stimulation, free radicals including H(2)O(2) are produced. We have developed a method of intracellular drug delivery using albumin microcapsules. Catalase would be an excellent compound to alter H(2)O(2) production. However, the large molecular size of catalase limits cellular penetration. Endothelial cells have been previously shown to readily phagocytoze albumin microcapsules.


METHODS
Catalase was added to an albumin solution to form a 10% solution of catalase. Microspheres from 2 to 7 microm in size were formed using a Bucchi spray dryer. Human endothelial cells were incubated with varying concentrations of microencapsulated catalase. The cells were then exposed to Escherichia coli endotoxin to determine if increased intracellular penetration of catalase would inhibit H(2)O(2), nitrate, and cytokine synthesis.


RESULTS
There was a 7.2-fold increase in endothelial intracellular catalase after 48 h incubation. H(2)O(2) was inhibited by 72%, nitrate 96%, TNF 90%, IL1 21%, IL6 42%.


CONCLUSIONS
These results demonstrate that inhibition of H(2)O(2) as a result of increased intracellular delivery of catalase inhibits proinflammatory cytokine synthesis after endotoxin exposure.
Siwale
Rodney C
RC
Mercer University, College of Pharmacy and Health Sciences, Atlanta, Georgia 30341, USA.
Yeboah
George K
GK
Addo
Richard
R
Oettinger
Carl W
CW
D'Souza
Martin J
MJ
D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D002374:Catalase / Q000008:administration & dosage / Q000494:pharmacology*; D002417:Cattle; D002478:Cells, Cultured; D016207:Cytokines / Q000037:antagonists & inhibitors*; D004337:Drug Carriers / Q000737:chemistry; D042783:Endothelial Cells / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D004731:Endotoxins; D006801:Humans; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors*; D008863:Microspheres; D010316:Particle Size; D017382:Reactive Oxygen Species / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000737:chemistry
D000975:Antioxidants; D016207:Cytokines; D004337:Drug Carriers; D004731:Endotoxins; D017382:Reactive Oxygen Species; D012710:Serum Albumin, Bovine; C044101:endotoxin, Escherichia coli; D006861:Hydrogen Peroxide; D002374:Catalase