Cysteine proteinases in bronchoalveolar epithelial cells and lavage fluid of rat lung.
We examined the presence of cathepsins B, H, and L in bronchoalveolar epithelial cells, including alveolar macrophages, and in bronchoalveolar lavage fluid (BALF), using immunocytochemistry and immunoblotting. By light and electron microscopy, immunoreactivity for cathepsins B, H, and L was detected in lysosomes of ciliated and non-ciliated epithelial cells of bronchi and bronchioles, and in macrophages. Immunodeposits for cathepsin H only were demonstrated in lamellar bodies of Type II alveolar epithelial cells, suggesting the cosecretion of surfactants and cathepsin H from the cells into the alveolar space. By immunoblotting, cathepsins B and H were found to be present in BALF. To further investigate the origin of these enzymes in BALF, alveolar macrophages obtained from BALF were cultured for 6 hr in a serum-free medium. Immunoblotting revealed that protein bands corresponding to the pro-form and mature form of cathepsin B and the mature form of cathepsin H were present in the culture medium. From these results, the presence of cathepsins B and H in BALF can be explained by the fact that cathepsin B is secreted from alveolar macrophages and cathepsin H is secreted mainly with surfactants from Type II cells and also from macrophages.
Ishii
Y
Y
Department of Respiratory Internal Medicine, University of Tsukuba, Japan.
Hashizume
Y
Y
Watanabe
T
T
Waguri
S
S
Sato
N
N
Yamamoto
M
M
Hasegawa
S
S
Kominami
E
E
Uchiyama
Y
Y
D000818:Animals; D015153:Blotting, Western; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology* / Q000201:enzymology; D002401:Cathepsin B / Q000378:metabolism; D056655:Cathepsin H; D056668:Cathepsin L; D002403:Cathepsins / Q000378:metabolism; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D010450:Endopeptidases; D004847:Epithelial Cells; D004848:Epithelium / Q000201:enzymology / Q000648:ultrastructure; D007150:Immunohistochemistry / Q000379:methods; D008247:Lysosomes / Q000378:metabolism / Q000648:ultrastructure; D008264:Macrophages / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D011650:Pulmonary Alveoli / Q000166:cytology* / Q000201:enzymology / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains
D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; D056668:Cathepsin L; C534280:Ctsl protein, rat; D056655:Cathepsin H; C534128:Ctsh protein, rat