Organic extract of tire debris causes localized damage in the plasma membrane of human lung epithelial cells.
The potential toxicity of tire debris organic extracts on human alveolar epithelial cells (A549) was investigated. We analysed time- and dose dependent modifications produced on plasma membrane molecular composition and on lipid microdomains expression (caveolae and lipid rafts) that represent specific signalling platforms. Cells were exposed to increasing organic extract concentrations (10, 60 and 75mug/ml) for 24, 48 and 72h. An up to three fold dose and time dependent increase in specific protein markers of lipid microdomains was found, suggesting a corresponding increase in signalling platforms. Since the total pool of these plasma membrane markers was unchanged, we supposed that these proteins were translocated within the plasma membrane as to assemble the newly formed lipid microdomains. Despite no major modifications in lipid bilayer composition, a time- and dose dependent toxic effect was documented at 48h of exposure by an increase of cells positive to Trypan Blue assay. After 48h a dose dependent increase in the cell medium of the cytosolic enzyme lactate dehydrogenase was also observed, indicating greater damage of the plasma membrane as prenecrotic sign. The overall ultrastructural morphology of the plasma membrane of treated cells was not greatly modified, suggesting that organic extracts from tire debris cause focalized discontinuities on cell surfaces.
Beretta
E
E
Department of Experimental Medicine, Via Cadore 48, 20052 Monza, University of Milano-Bicocca, Italy.
Gualtieri
M
M
Botto
L
L
Palestini
P
P
Miserocchi
G
G
Camatini
M
M
D021941:Caveolae / Q000187:drug effects; D045744:Cell Line, Tumor; D002463:Cell Membrane Permeability / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000633:toxicity*; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D008168:Lung / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D008563:Membrane Lipids / Q000378:metabolism; D021962:Membrane Microdomains / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D008565:Membrane Proteins / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D021381:Protein Transport / Q000187:drug effects; D012408:Rubber / Q000633:toxicity*; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors
D004785:Environmental Pollutants; D008563:Membrane Lipids; D008565:Membrane Proteins; D012408:Rubber