Asbestos causes translocation of p65 protein and increases NF-kB DNA binding activity in rat lung epithelial and pleural mesothelial cells.
Janssen-YM; Driscoll-KE; Howard-B; Quinlan-TR; Treadwell-M; Barchowsky-A; Mossman-BT
Am J Pathol 1997 Aug; 151(2):389-401
The effects of asbestos (1332214) on pulmonary nuclear-factor-kappa- B (NF-kB) activity were studied in rats. Male Fischer-rats were exposed to 0 or 8.25mg/m3 chrysotile (12001295) or 7.20mg/m3 crocidolite (12001284) dust for 6 hours (hr), 5 days per week (day/wk) for 5 or 20 days. Selected rats were killed after 5 and 20 days and the lungs were removed. The lungs were sliced into 5 micrometer thick sections which were examined for p65, a protein subunit of NF-kB, using an immunofluorescence technique. Rat lung epithelial (RLE) and pleural mesothelial (RPM) cells were incubated with 0 to 20 micrograms per square centimeter crocidolite or riebeckite, a nonfibrous particulate analogue of crocidolite, or glass beads for comparison purposes, for 4 or 8hr. Some cell cultures were treated with Escherichia-coli lipopolysaccharide (LPS) as a positive control. The effects on nuclear protein binding to NF- kB DNA consensus sequences were examined using an electrophoretic mobility shift assay. The localization of p65 in the cells was determined by confocal microscopy. Inhalation of either chrysotile or crocidolite caused a significant increase in p65 immunofluorescence in airway epithelial cells after both 5 and 20 days. The effects were most pronounced in bronchial epithelial cells after 5 days exposure. Focal increases in p65 immunoreactivity were seen in interstitial lung compartments, the alveolar ducts, and in the bifurcations. No significant changes in p65 expression were seen in pleural mesothelial cells. In-vitro treatment with crocidolite caused significant dose related increases in p65 binding to NF-kB consensus DNA sequences in both RLE and RPM cells. A stronger response was seen following treatment with LPS. Riebeckite and glass beads had no significant effects on p65 binding to NF-kB DNA. Crocidolite caused a partial (50%) translocation of p65 from the cytoplasm to the nucleus in RPM cells. LPS caused a more than 90% translocation of p65 into the nucleus. The authors conclude that this study is the first to document the presence of the NF-kB system in lung tissue and to provide evidence that it is activated by asbestos. The activation of NF-kB and translocation of NF-kB genes may play a role in the chronic inflammation seen in the lungs of experimental animals and workers after occupational exposure to asbestos.
NIOSH-Publication; NIOSH-Grant; Pulmonary-system-disorders; Asbestos-fibers; Proteins; Inhalation-studies; Lung-cells; Nucleic-acids; Inhalation-studies; Bioactivation; Immunochemistry
Dr. Yvonne M. W. Janssen, University of Vermont College of Medicine, Department of Pathology, Burlington, VT 05405-0068
1332-21-4; 12001-29-5; 12001-28-4
American Journal of Pathology
Pathology University of Vermont Medical Alumni Bldg a 249 Burlington, VT 05405-0068