Brief inhalation of chrysotile asbestos induces rapid proliferation of bronchiolar-alveolar epithelial and interstitial cells.
Inhalation of asbestos fibres causes a progressive interstitial pulmonary fibrosis. To understand the basic cellular mechanisms which lead to this disease, we have studied the earliest proliferative events at the bronchiolar-alveolar regions of rats and mice exposed to chrysotile asbestos for 5 h. Animals were injected with tritiated thymidine 4 h prior to sacrifice at varying times ranging from immediately after cessation of exposure to one month post exposure. Light microscopic autoradiography showed that air-exposed control animals never had more than 1% of cells labelled. Rats and mice studied immediately after exposure also had normal numbers of labelled cells. However, between 12 and 48 h post exposure, asbestos-exposed animals exhibited up to 4-fold increases in the percentages of labelled epithelial and interstitial cells. Normal labelling returned by 8 days after exposure and was maintained through the one-month period studied. We conclude that inhalation of chrysotile asbestos induces rapid and highly significant increases in proliferation of epithelial and interstitial cells of the bronchiolar-alveolar regions where asbestos fibres were initially deposited.
Brody
A R
AR
Laboratory of Pulmonary Pathobiology, National Institute of Environmental Health Sciences, Research Triangle Park, NC.
McGavran
P D
PD
Overby
L H
LH
D000280:Administration, Inhalation; D000818:Animals; D001194:Asbestos / Q000494:pharmacology*; D017632:Asbestos, Serpentine; D001980:Bronchi / Q000473:pathology*; D003238:Connective Tissue / Q000473:pathology; D004848:Epithelium / Q000473:pathology; D008297:Male; D051379:Mice; D011650:Pulmonary Alveoli / Q000473:pathology*; D051381:Rats; D011916:Rats, Inbred F344
D017632:Asbestos, Serpentine; D001194:Asbestos