Chrysotile asbestos causes AEC apoptosis via the caspase activation in vitro and in vivo.
To determine whether alveolar epithelial cell (AEC) apoptosis via caspase activation is involved in asbestos-induced lung injury, we examined apoptosis, caspase-3 and-9 activation using chrysotile asbestos exposure models in vitro and in vivo. Apoptotic cells were assessed in A549 cells with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method after 48 hours exposure of chrysotile asbestos (5 to 100 ug/cm2). Asbestos exposure induced a dose-dependent increase of apoptotic cells, and both pretreatment with Z-LEHD-FMK (caspase-3 inhibitor) or Z-DEMK-FMK (caspase-9 inhibitor) significantly suppressed asbestos-induced apoptosis. Expression of cleaved caspase-3 and-9 increased significantly from 18 to at least 48 hours after asbestos exposure. In vivo study, either 1 or 2 mg of chrysotile asbestos were administered into rat lungs intratracheally, and the lungs were obtained 3 days, 1 and 2 weeks, 1, 3 and 6 months after the administration. Asbestos exposure increased the number of apoptotic cells and the activation of cleaved caspase-3 and -9 most at 3 days in a dose dependent manner, and continued to increase them until at least 6 months after asbestos exposure. Apoptotic cells and cleaved caspase-3 and -9 positive cells were mainly observed in AECs. These findings suggest that AEC apoptosis via caspase-3 and -9 activation is involved in asbestos-induced lung injury.
Kido
Takashi
T
Department of Respiratory Disease, University of Occupational and Environmental Health, Fukuoka, Japan. t-kido@med.uoeh-u.ac.jp
Morimoto
Yasuo
Y
Asonuma
Etsuko
E
Yatera
Kazuhiro
K
Ogami
Akira
A
Oyabu
Takako
T
Tanaka
Isamu
I
Kido
Masamitsu
M
D000393:Air Pollutants / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D017632:Asbestos, Serpentine / Q000633:toxicity*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism*; D053453:Caspase 9 / Q000378:metabolism*; D061945:Caspase Inhibitors; D002452:Cell Count; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019085:Fluorescent Antibody Technique, Direct; D015745:Granuloma, Foreign-Body / Q000139:chemically induced / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D020287:In Situ Nick-End Labeling; D007442:Intubation, Intratracheal; D008168:Lung / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D008297:Male; D010316:Particle Size; D011650:Pulmonary Alveoli / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar
D000393:Air Pollutants; D017632:Asbestos, Serpentine; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D053148:Caspase 3; D053453:Caspase 9