Exposure of endothelial cells to free heme potentiates damage mediated by granulocytes and toxic oxygen species

G. Balla, G. M. Vercellotti, U. Muller-Eberhard, J. Eaton, H. S. Jacob

Research output: Contribution to journalArticle

240 Citations (Scopus)

Abstract

Endothelial damage may follow exposure to toxic oxygen species generated by closely apposed (''marginated'') granulocytes. Because iron markedly catalyzes oxidant damage in diverse systems, we wondered whether intercalculated heme, and/or its constituent iron, might potentiate oxidant damage of endothelium. Cultured monolayers of porcine aortic endothelial cells were exposed for brief periods to purified hemin. Uptake of heme was rapid, dose dependent, and not reversible by buffer or serum washes. Despite high levels of cell-associated heme, no direct heme-mediated cytotoxicity occurred, but heme-loaded endothelium became highly sensitive to oxidant challenge by (a) reagent H2O2, (b) enzymatically generated oxidants (xanthine/xanthine oxidase), or (c) phorbol-activated polymorphonuclear leukocytes. An increase in endothelial cell lipid peroxidation accompanied heme-augmented oxidant cytolysis, and both parameters were reduced in parallel by micromolar amounts of the hydrophobic oxygen radical scavenger/iron chelator U74500A. Endothelial uptake of heme was inhibited by a specific heme-binding protein, hemopexin. Concomitantly, hemopexin completely blocked augmented H2O2- and polymorphonuclear leukocyte-mediated cytotoxicity but only if added simultaneously and stoichiometrically with hemin. Significant loss of protection occurred if hemopexin addition was delayed 15 minutes, and protection was completely lost after a 60-minute interval. The iron moiety of heme was critical to oxidant sensitization because neither iron-free protoporphyrin IX nor tin-protoporphyrin was able to sensitize endothelial cells to H2O2 or activated polymorphonuclear leukocytes. These results may provide mechanistic insights into atherogenesis, reperfusion injury, and the organ injury accompanying hemoglobinemia or myoglobinemia.

Original languageEnglish
Pages (from-to)648-655
Number of pages8
JournalLaboratory Investigation
Volume64
Issue number5
Publication statusPublished - 1991

Fingerprint

Poisons
Heme
Granulocytes
Endothelial Cells
Oxidants
Oxygen
Hemopexin
Iron
Hemin
Neutrophils
Endothelium
Xanthine
Xanthine Oxidase
Chelating Agents
Reperfusion Injury
Lipid Peroxidation
Reactive Oxygen Species
Atherosclerosis
Buffers
Swine

Keywords

  • Iron
  • Oxygen radicals

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

Cite this

Balla, G., Vercellotti, G. M., Muller-Eberhard, U., Eaton, J., & Jacob, H. S. (1991). Exposure of endothelial cells to free heme potentiates damage mediated by granulocytes and toxic oxygen species. Laboratory Investigation, 64(5), 648-655.

Exposure of endothelial cells to free heme potentiates damage mediated by granulocytes and toxic oxygen species. / Balla, G.; Vercellotti, G. M.; Muller-Eberhard, U.; Eaton, J.; Jacob, H. S.

In: Laboratory Investigation, Vol. 64, No. 5, 1991, p. 648-655.

Research output: Contribution to journalArticle

Balla, G, Vercellotti, GM, Muller-Eberhard, U, Eaton, J & Jacob, HS 1991, 'Exposure of endothelial cells to free heme potentiates damage mediated by granulocytes and toxic oxygen species', Laboratory Investigation, vol. 64, no. 5, pp. 648-655.
Balla, G. ; Vercellotti, G. M. ; Muller-Eberhard, U. ; Eaton, J. ; Jacob, H. S. / Exposure of endothelial cells to free heme potentiates damage mediated by granulocytes and toxic oxygen species. In: Laboratory Investigation. 1991 ; Vol. 64, No. 5. pp. 648-655.
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