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Infect. Immun., 01 1998, 191-196, Vol 66, No. 1
RA Fratti, PH Belanger, MA Ghannoum, JE Edwards Jr and SG Filler
Although it is known that Candida albicans causes endothelial cell injury,
in vitro and in vivo, the mechanism by which this process occurs remains
unknown. Iron is critical for the induction of injury in many types of host
cells. Therefore, we investigated the role of iron in Candida-induced
endothelial cell injury. We found that pretreatment of endothelial cells
with the iron chelators phenanthroline and deferoxamine protected them from
candidal injury, even though the organisms germinated and grew normally.
Loading endothelial cells with iron reversed the cytoprotective effects of
iron chelation. Moreover, chelation of endothelial cell iron significantly
reduced phagocytosis of C. albicans by these cells, while candidal
adherence to chelator- treated endothelial cells was slightly enhanced.
Since endothelial cell phagocytosis of C. albicans is required for
endothelial cell injury to occur, inhibition of phagocytosis is likely the
principal mechanism of the cytoprotective effects of iron chelation. The
production of toxic reactive oxygen intermediates by host cells is known to
be inhibited by iron chelation. Therefore, we investigated whether treating
endothelial cells with antioxidants could mimic the cytoprotective effects
of iron chelation. Neither extracellular nor membrane-permeative
antioxidants reduced candidal injury of endothelial cells. Furthermore,
depleting endothelial cells of the endogenous antioxidant glutathione did
not render them more susceptible to damage by C. albicans. These results
suggest that candidal injury of endothelial cells is independent of the
production of reactive oxygen intermediates and that the cytoprotective
effects of iron chelation are not due to inhibition of the synthesis of
these toxic intermediates.
Copyright © 1998, American Society for Microbiology
Endothelial cell injury caused by Candida albicans is dependent on iron
St. John's Cardiovascular Research Center, Department of Medicine, Harbor-UCLA Research and Education Institute, Torrance, California 90502, USA.
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