Protease production by cultured microglia: substrate gel analysis and immobilized matrix degradation.
The production of collagen-degrading proteases by cultured neonatal rat microglia was examined using an immobilized fibronectin-gelatin matrix coupled to a fluorescent marker and by substrate gel analysis. When microglia were plated onto the surface of the matrix and incubated under resting (nonstimulated) conditions, a small but visible amount of immobilized matrix was degraded. Treatment with lipopolysaccharide (LPS) or interleukin-1 (IL-1) significantly increased the number of microglia demonstrating substrate degradation. Substrate-SDS polyacrylamide gel electrophoresis of samples of supernatants from untreated cultured microglia indicated the presence of a 72 and a 92 kD metalloproteinase with characteristics corresponding to collagenases. Supernatants from untreated astrocyte cultures were shown to have primarily a 72 kD metalloproteinase. Proteinase activity increased on stimulation of the microglia with LPS and IL-1 in a dose-dependent fashion. These results indicate that cultured microglia release active proteases capable of degrading the extracellular matrix in a localized region. The production of proteases by activated microglia may have important physiological and pathophysiological consequences within the restricted extracellular matrix of the CNS.
Colton
C A
CA
Department of Physiology and Biophysics, Georgetown University Medical School, Washington, DC 20007.
Keri
J E
JE
Chen
W T
WT
Monsky
W L
WL
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D017364:Collagenases / Q000096:biosynthesis*; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D005109:Extracellular Matrix / Q000201:enzymology; D005353:Fibronectins / Q000378:metabolism; D005780:Gelatin / Q000378:metabolism; D007375:Interleukin-1 / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D009457:Neuroglia / Q000201:enzymology*; D051381:Rats
D003470:Culture Media; D005353:Fibronectins; D007375:Interleukin-1; D008070:Lipopolysaccharides; D005780:Gelatin; D003094:Collagen; D017364:Collagenases