Alveolar macrophage secretion of a 92-kDa gelatinase in response to bleomycin.
These experiments were conducted to study the possible involvement of macrophage-derived gelatinases in the bleomycin-induced model of pulmonary fibrosis. Normal rat alveolar macrophages and the rat alveolar macrophage cell line NR8383 were stimulated in vitro with 0-1.0 microgram/ml bleomycin for 18 h. Gelatinase activity in the medium was assayed on zymograms in which gelatin or collagen were used as substrates. Macrophages stimulated with 0.01-1.0 microgram/ml of bleomycin secreted significantly more of a 92-kDa gelatinase than did unstimulated controls. Addition of cycloheximide during stimulation decreased gelatinase activity by 86 +/- 4%, and activity was completely inhibited by the addition of EDTA to zymograms. This gelatinase degraded denatured type I collagen and native type IV collagen. Western blot analysis using a monoclonal mouse anti-rat antibody demonstrated that this enzyme was the same as a metalloproteinase secreted by rat mammary carcinoma cells. Gelatinase secreted by macrophages in fibrotic lungs may enhance macrophage migration through the lung and may also be active in the remodeling process.
Denholm
E M
EM
Division of Hematology, Albany Medical College, New York 12208.
Rollins
S M
SM
D000818:Animals; D001761:Bleomycin / Q000494:pharmacology*; D002460:Cell Line; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D018093:Gelatinases / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008970:Molecular Weight; D051381:Rats; D011916:Rats, Inbred F344
D017077:Culture Media, Conditioned; D001761:Bleomycin; D018093:Gelatinases