About this Journal Submit a Manuscript Table of Contents
Mediators of Inflammation
Volume 4 (1995), Issue 6, Pages 437-443
http://dx.doi.org/10.1155/S0962935195000706

Cytotoxicity towards human endothelial cells, induced by neutrophil myeloperoxidase: protection by ceftazidime

1Centre for the Biochemistry of Oxygen, Institut de Chimie, B6, Université de Liège, Domaine Universitaire du Sart Tilman, Liège 4000, Belgium
2Department of Anesthesiology and Intensive Care Medicine, Centre Hospitalier Universitaire, B35, Domaine Universitaire du Sart Tilman, Liège 4000, Belgium
3Glaxo Belgium sa, Boulevard du Triomphe, 172, Bruxelles, Belgium

Copyright © 1995 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We investigated the effects of the antibiotic ceftazidime (CAZ) on the cytolytic action of the neutrophil myeloperoxidase–hydrogen peroxide–chloride anion system (MPO/H2O2/Cl). In this system, myeloperoxidase catalyses the conversion of H2O2 and CI to the cytotoxic agent HOCl. Stimulated neutrophils can release MPO into the extracellular environment and then may cause tissue injury through direct endothelial cells lysis. We showed that human umbilical vein endothelial cells (HUVEC) were capable of taking up active MPO. In presence of H2O2 (10−4 M), this uptake was accompanied by cell lysis. The cytolysis was estimated by the release of 51Cr from HUVEC and expressed as an index of cytotoxicity (IC). Dose dependent protection was obtained for CAZ concentrations ranging from 10−5 to 10−3 M;this can be attributed to inactivation of HOCl by the drug. This protection is comparable to that obtained with methionine and histidine, both of which are known to neutralize HOCl. This protection by CAZ could also be attributed to inactivation of H2O2, but when cytolysis was achieved with H2O2 or O2 generating enzymatic systems, no protection by CAZ was observed. Moreover, the peroxidation activity of MPO (action on H2O2) was not affected by CAZ, while CAZ prevented the chlorination activity of MPO (chlorination of monochlorodimedon). So, we concluded that CAZ acts via HOCl inactivation. These antioxidant properties of CAZ may be clinically useful in pathological situations where excessive activation of neutrophils occurs, such as in sepsis.