In vitro killing of Actinobacillus actinomycetemcomitans and Capnocytophaga spp. by human neutrophil cathepsin G and elastase.
The purpose of this study was to compare the killing of Actinobacillus actinomycetemcomitans with that of Capnocytophaga spp. by purified cathepsin G and elastase in vitro. Both were sensitive to killing by purified cathepsin G, but only the Capnocytophaga spp. were killed by elastase. Killing by cathepsin G exhibited logarithmic kinetics, was enhanced slightly by alkaline pH, and was enhanced greatly under hypotonic conditions. Treatment of cathepsin G with diisopropyl fluorophosphate significantly reduced its bactericidal activity against Capnocytophaga spp. but not against Escherichia coli or A. actinomycetemcomitans. The bactericidal effects of cathepsin G against Capnocytophaga sputigena and A. actinomycetemcomitans were inhibited by alpha-1-antichymotrypsin, alpha-1-antitrypsin, and alpha-2-macroglobulin but not by bovine serum albumin. We conclude that (i) cathepsin G kills Capnocytophaga spp. and A. actinomycetemcomitans, (ii) elastase kills Capnocytophaga spp., (iii) the bactericidal activity of cathepsin G is enzyme dependent against Capnocytophaga spp. and enzyme independent against A. actinomycetemcomitans, and (iv) natural plasma antiproteases may control both enzyme-dependent and enzyme-independent bactericidal activities of cathepsin G.
Miyasaki
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KT
Section of Oral Biology, UCLA School of Dentistry, Center for the Health Sciences 90024.
Bodeau
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AL
D000188:Actinobacillus / Q000187:drug effects / Q000276:immunology*; D002206:Capnocytophaga / Q000187:drug effects / Q000276:immunology*; D056649:Cathepsin G; D002403:Cathepsins / Q000037:antagonists & inhibitors / Q000276:immunology* / Q000494:pharmacology; D015169:Colony Count, Microbial; D006801:Humans; D007531:Isoflurophate / Q000494:pharmacology; D007700:Kinetics; D009504:Neutrophils / Q000201:enzymology*; D009994:Osmolar Concentration; D010196:Pancreatic Elastase / Q000276:immunology* / Q000494:pharmacology; D012697:Serine Endopeptidases
D007531:Isoflurophate; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; D010196:Pancreatic Elastase