Ozone-mediated cytotoxicity after short-term exposure and its relation to the production of cellular metabolites (NO,H2O2) |
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Authors: | Klestadt D Laval-Gilly P Falla J |
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Institution: | (1) Département Génie Biologique – Génie de l'Environnement, Laboratoire d'Immunologie – Microbiologie, Institut Universitaire de Technologie de Metz, Yutz, F rance |
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Abstract: | Alveolar macrophages secrete numerous mediators, playing an important role in host defence. Among these mediators, nitric
oxide (NO) and hydrogen peroxide (H2O2) are both involved in bactericidal killing and trigger the release of other cellular metabolites. We have analyzed the effect
of an atmosphere polluted with ozone (0.03–0.5 ppm v/v) on the monocytic cell line THP-1, as a model for alveolar macrophages,in vitro. NO and H2O2 were chosen to evaluate cell response to ozone. Cell injury was evaluated using lactate dehydrogenase (LDH) liberation into
the medium. An exposure to 0.5 ppm ozone proved to be more toxic to the cells, than 0.1 or 0.03 ppm, evidenced by more LDH
being liberated and cytotoxicity reaching values up to 64%. For all ozone concentrations, H2O2 production reached a peak value after 10–15 min of exposure, after which the concentration of extracellular H2O2 production diminished rapidly. The highest NO concentrations were measured with 0.5 ppm ozone, reaching a maximum value of
1460 nmol/L per 5×106 cells, which is 1.55 times higher than for nonexposed cells. Lower concentrations barely induced higher NO concentrations
compared to nonexposed cells. The results indicate that ozone effects not only the viability of human monocytes but also the
release of antibacterial and defense signaling molecules and suggest that ozone-mediated cytotoxicity may be related to the
secretion of NO and H2O2.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | hydrogen peroxide immunotoxicity in vitro exposure nitric oxide ozone THP-1 cells |
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