PROPERTIES OF MACROPHAGE ELASTASE.
Item
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Title
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PROPERTIES OF MACROPHAGE ELASTASE.
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Identifier
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AAI8601654
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identifier
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8601654
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Creator
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HOROWITZ, MITCHELL BARRY.
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Contributor
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Jerome Kleinerman
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Date
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1985
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Language
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English
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Publisher
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City University of New York.
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Subject
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Health Sciences, Pathology
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Abstract
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Horseradish peroxidase-coupled elastin was used to confirm the elastolytic potential of alveolar macrophage (AM) conditioned medium (CM). AM were collected via bronchoalveolar lavage from DBA/2 mice. After 60 h in culture, the CM of 1.5 x 10('6) AM contained in vitro elastolytic activity equivalent to 125 ng of porcine pancreatic elastase (PPE). This represented a distinct AM-derived elastase, rather than contaminating neutrophil elastase, since (1) it had the characteristics of a metalloproteinase; (2) it was resistant to inactivation by serine protease inhibitors; (3) it was continuously discharged during culture; (4) its pH profile differed from that reported for neutrophil elastase, and (5) its secretion was dependent upon AM protein synthesis. Elastolytic activity was also detected in the CM of the P388D(,1) macrophage cell line, from which a homogeneous 15k MW elastase was isolated by affinity chromatography.;CM from AM cultured in the presence of 2 (mu)M colchicine contained 360% the elastase activity of controls. A similar effect was obtained with nocodazole, an unrelated microtubule-disrupting agent, but not with taxol, which promotes microtubule assembly. Theophylline alone more than doubled elastase secretion, and combined with colchicine produced a 5-fold increase. Cycloheximide eliminated basal elastase activity but failed to suppress 12% of colchicine-induced elastase secretion, suggesting the presence of a small, intracellular pool of AM elastase. Although alpha(,2)-macroglobulin ((alpha)(,2)-M) inhibited AM elastase, endogenous (alpha)(,2)-M did not appear to be masking elastase activity since methylamine, which inactivates (alpha)(,2)-M, did not increase free elastase. Methylamine did, however, produce a 6-fold increase in (beta)-glucuronidase secretion, which suggests AM elastase is not similarly lysosomally stored.;To assess the in vivo elastolytic potential of AM elastase, AM CM containing in vitro activity equivalent to 500 ng PPE was instilled intratracheally into 5 DBA/2 mice. After 2 weeks, although mean linear intercept (Lm), an index of airway diameter, was not significantly increased, histologic lung sections from 3 mice revealed areas suggestive of emphysema. However, as these subjective impressions were not corroborated by the Lm data, a definitive role for AM elastase in the pathogenesis of emphysema awaits future studies using higher elastase challenges.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Biomedical Sciences
