Carbocisteine inhibits oxidant-induced apoptosis in cultured human airway epithelial cells.
OBJECTIVE
Increased oxidant levels have been associated with exacerbations of COPD, and L-carbocisteine, a mucolytic agent, reduces the frequency of exacerbations. The mechanisms underlying the inhibitory effects of L-carbocisteine on oxidant-induced COPD exacerbations were examined in an in vitro study of human airway epithelial cells.


METHODS
In order to examine the antioxidant effects of L-carbocisteine, human tracheal epithelial cells were treated with L-carbocisteine and exposed to hydrogen peroxide (H(2)O(2)). Cell apoptosis was assessed using a cell death detection ELISA, and the pathways leading to cell apoptosis were examined by measurement of caspase-3 and caspase-9 by western blot analysis with fluorescent detection.


RESULTS
The proportion of apoptotic cells in human tracheal epithelium was increased in a concentration- and time-dependent manner, following exposure to H(2)O(2). Treatment with L-carbocisteine reduced the proportion of apoptotic cells. In contrast, H(2)O(2) did not increase the concentration of LDH in supernatants of epithelial cells. Exposure to H(2)O(2) activated caspase-3 and caspase-9, and L-carbocisteine inhibited the H(2)O(2)-induced activation of these caspases. L-carbocisteine activated Akt phosphorylation, which modulates caspase activation, and the inhibitors of Akt, LY294002 and wortmannin, significantly reversed the inhibitory effects of L-carbocisteine on H(2)O(2)-induced cell apoptosis.


CONCLUSIONS
These findings suggest that in human airway epithelium, L-carbocisteine may inhibit cell damage induced by H(2)O(2) through the activation of Akt phosphorylation. L-carbocisteine may have antioxidant effects, as well as mucolytic activity, in inflamed airways.
Yoshida
Motoki
M
Department of Geriatrics, Tohoku University School of Medicine, Sendai, Japan. mtkyoshida@idac.tohoku.ac.jp
Nakayama
Katsutoshi
K
Yasuda
Hiroyasu
H
Kubo
Hiroshi
H
Kuwano
Kazuyoshi
K
Arai
Hiroyuki
H
Yamaya
Mutsuo
M
D017209:Apoptosis / Q000187:drug effects*; D002233:Carbocysteine / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D002478:Cells, Cultured; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005100:Expectorants / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D020545:Respiratory Mucosa / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D014132:Trachea / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism
D005100:Expectorants; D002233:Carbocysteine; D006861:Hydrogen Peroxide; D051057:Proto-Oncogene Proteins c-akt; D053148:Caspase 3; D053453:Caspase 9