interleukin-8 and thiobarbituric-acid

Epidemiological studies have linked the inhalation of airborne particulate matter (PM) to increased morbidity and mortality in humans. However, the mechanisms of toxicity of these particles remain unclear. Some hypotheses state that the toxicity might stem from PM transition metal content, adhered organic compounds, the biological component, or ultrafine particle content. In order to analyze metal involvement in PM toxicity, human airway epithelial cell line (BEAS-2B) cultures were exposed for 24 h to an aqueous extract of PM collected in the Utah Valley. A portion of the extract was treated with Chelex, an agent that removes cations (including transition metals) from solution. Removal of the majority of the metal mass was confirmed by inductively coupled plasma (ICP) analyses. Cells that were incubated with the untreated extract (62-1000 microg dry extract equivalent) showed a significant concentration-dependent increase in the inflammatory mediator interleukin-8 (IL-8) when compared to the control cells. However, cells incubated with Chelex-treated extract produced no change (relative to control) in IL-8. We exposed rats in vivo for 24 h to the same treatments as the cells and found significant increases in lactate dehydrogenase (LDH) and total protein in the rats exposed to the untreated extract and to the Chelex-treated extract with metals added back to achieve original concentrations. There was an attenuation of the observed LDH and total protein increases in the rats instilled with the Chelex-treated extract. Taken together, our results suggest that removal of metal cations attenuates cellular responses to the aqueous extract and support a role for transition metal involvement in PM-associated increases in morbidity and mortality.

Topics: Air Pollutants; Animals; Bronchi; Bronchoalveolar Lavage Fluid; Cell Line, Transformed; Chelating Agents; Dose-Response Relationship, Drug; Environmental Monitoring; Epithelial Cells; Humans; Interleukin-8; Intubation, Intratracheal; L-Lactate Dehydrogenase; Male; Metals, Heavy; Polystyrenes; Polyvinyls; Proteins; Rats; Rats, Sprague-Dawley; Specific Pathogen-Free Organisms; Thiobarbiturates; Utah

The presence in plasma of an electronegative LDL subfraction [LDL(-)] cytotoxic for endothelial cells (ECs) has been reported. We studied the effect of LDL(-) on the release by ECs of molecules implicated in leukocyte recruitment [interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1)] and in the plasminogen activator inhibitor-1 (PAI-1). LDL(-), isolated by anion-exchange chromatography, differed from nonelectronegative LDL [LDL(+)] in its higher triglyceride, nonesterified fatty acid, apoprotein E and apoprotein C-III, and sialic acid contents. No evidence of extensive oxidation was found in LDL(-); its antioxidant and thiobarbituric acid-reactive substances contents were similar to those of LDL(+). However, conjugated dienes were increased in LDL(-), which suggests that mild oxidation might affect these particles. LDL(-) increased, in a concentration-dependent manner, the release of IL-8 and MCP-1 by ECs and was a stronger inductor of both chemokines than oxidized LDL (oxLDL) or LDL(+). PAI-1 release increased slightly in ECs incubated with both LDL(-) and oxLDL but not with LDL(+). However, no cytotoxic effects of LDL(-) were observed on ECs. Actinomycin D inhibited the release of IL-8 and MCP-1 induced by LDL(-) and oxLDL by up to 80%, indicating that their production is mediated by protein synthesis. Incubation of ECs with N:-acetyl cysteine inhibited production of IL-8 and MCP-1 induced by LDL(-) and oxLDL by >50%. The free radical scavenger butylated hydroxytoluene slightly inhibited the effect of oxLDL but did not modify the effect of LDL(-). An antagonist (BN-50730) of the platelet-activating factor receptor inhibited production of both chemokines by LDL(-) and oxLDL in a concentration-dependent manner. Our results indicate that LDL(-) shows proinflammatory activity on ECs and may contribute to early atherosclerotic events.

Topics: Acetylcysteine; Adult; Antioxidants; Cells, Cultured; Chemokine CCL2; Chromatography, Ion Exchange; Dactinomycin; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Endothelium, Vascular; Female; Free Radical Scavengers; Humans; Interleukin-8; Lipoproteins, LDL; Male; Middle Aged; Plasminogen Activator Inhibitor 1; Thiobarbiturates; Tumor Necrosis Factor-alpha