Lipid Ozonation Products Activate Phospholipases A2, C, and D

doi:10.1006/taap.1998.8418

Toxicology and Applied Pharmacology

Volume 150, Issue 2, June 1998, Pages 338-349

https://doi.org/10.1006/taap.1998.8418 Get rights and content

Abstract

Ozone exposure,in vitro,has been shown to activate phospholipases A₂(PLA₂), C (PLC), and D (PLD) in airway epithelial cells. However, because of its high reactivity, ozone cannot penetrate far into the air/lung tissue interface. It has been proposed that ozone reacts with unsaturated fatty acids (UFA) in the epithelial lining fluid (ELF) and cell membranes to generate a cascade of lipid ozonation products (LOP) that mediate ozone-induced toxicity. To test this hypothesis, we exposed cultured human bronchial epithelial cells (BEAS-2B) to LOP (1–100 μM) produced from the ozonation of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) and measured the activity of PLA₂, PLC, and PLD. The PLA₂isoform responsible for arachidonic acid release (AA) in stimulated cultures was also characterized. Activation of PLA₂, PLC, and PLD by three oxidants, hydrogen peroxide (H₂O₂),tert-butyl hydroperoxide (t-BOOH) and 2,2′-azobis(2-amidinopropane)dihydrochloride (AAPH) also was measured and compared to that of LOP. The derivatives of ozonized POPC at thesn-2 residue, 9-oxononanoyl (PC-ALD), 9-hydroxy-9-hydroperoxynonanoyl (PC-HHP), and 8-(-5-octyl-1,2,4-trioxolan-3-yl-) octanoyl (POPC-OZ) selectively activated PLA₂in a dose-dependent fashion. Cytosolic PLA₂(cPLA₂) measured in the cytosolic fraction of stimulated cell lysates was found to be the predominant isoform responsible for AA release. PLC activation was exclusively induced by the hydroxyhydroperoxide derivatives. PC-HHP and the 9-carbon hydroxyhydroperoxide (HHP-C9) increased PLC activity. PLD activity also was induced by LOP generated from POPC. Incubation of cultures with H₂O₂alone did not stimulate PLC; however, in the presence of the aldehyde, nonanal, a 62 ± 2% increase in PLC activity was found, suggesting that the increase in activity was due to the formation of the intermediate HHP-C9. t-BOOH, and AAPH also failed to induce PLA₂activation, but did activate PLC, under conditions of exposure identical to that of LOP. Only t-BOOH activated PLD. These results suggest that biologically relevant concentrations of LOP activate PLA₂, PLC, and PLD in the airway epithelial cell, a primary target to ozone exposure. The activation of these phospholipases may playa role in the development of lung inflammation during ozone exposure.

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^☆: W. J. LymanW. F. ReehleD. H. Rosenblatt

¹: To whom correspondence should be addressed.

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Regular ArticleLipid Ozonation Products Activate Phospholipases A2, C, and D☆

Abstract

Chest

Neuroprotocols

J. Biol. Chem.

Toxicol. Appl. Pharmacol.

Biochim. Biophys. Acta

Biochim. Biophys. Acta

Biochim. Biophys. Acta

Trends Biochem. Sci.

Toxicol. Appl. Pharmacol.

Environ. Res.

Toxicol. Appl. Pharmacol.

Free Radical Biol. Med.

Free Radical Biol. Med.

Fundam. Appl. Pharmacol.

Free Radical Biol. Med.

Chem–Biol. Interact.

Free Radical Biol. Med.

Methods Enzymol.

Eur. J. Pharmacol.

Free Radical Biol. Med.

Life Sci.

Life Sci.

Anal. Biochem.

Biochim. Biophys. Acta

Toxicol. Appl. Pharmacol.

Fundam. Appl. Toxicol.

Platelet-activating factor provokes release of mucin-like glycoproteins from guinea pig respiratory epithelial cells via a lipoxygenase-dependent mechanism

Am. J. Respir. Cell Mol. Biol.

Ozone and unsaturated fatty acids

Arch. Environ. Health

Ozone-induced decrements in FEV1 and FVC do not correlate with measures of inflammation

Am. J. Respir. Dis. Crit. Care Med.

Pulmonary epithelial permeability in rats exposed to O3

J. Toxicol. Environ. Health

A rapid method of total lipid extraction and purification

Can. J. Biochem. Physiol.

Mechanism of ozonolysis

Angew. Chem. Int. Ed.

Ozone-induced release of cytokines and fibronectin production by alveolar macrophages and airway epithelial cells

Am. J. Physiol.

Exposure of humans to ambient levels of ozone for 6.6 hours causes cellular and biochemical chanches in the lung

Am. J. Respir. Cell Mol. Biol.

Regular Article
Lipid Ozonation Products Activate Phospholipases A₂, C, and D☆

Pulmonary epithelial permeability in rats exposed to O₃