Intracellular and extracellular enzymatic deacylation of bacterial endotoxin during localized inflammation induced by Escherichia coli.
Acyloxyacyl hydrolase (AOAH), an enzyme that removes the secondary acyl chains of gram-negative bacterial lipid A (endotoxin), has been identified previously in human neutrophils and mouse macrophages. We report here that bovine leukocytes also contain AOAH activity. Although bovine AOAH deacylates bacterial lipopolysaccharide in a manner similar to human AOAH, it is active in vitro over a broader pH range, from 4.0 to 7.0. By using Escherichia coli infection of the bovine mammary gland as a model of localized gram-negative bacterial disease and associated tissue inflammation, AOAH activity per leukocyte increased. In addition, AOAH activity increased in the cell-free portion of infected mammary secretions. These data indicate that AOAH activity increases in leukocytes associated with inflammation induced by gram-negative bacteria and provide additional evidence of its potential involvement in the defense against the effects of bacterial endotoxin.
McDermott
C M
CM
Department of Pathology, College of Veterinary Medicine, Kansas State University, Manhattan 66506.
Cullor
J S
JS
Fenwick
B W
BW
D000818:Animals; D002265:Carboxylic Ester Hydrolases / Q000032:analysis*; D002417:Cattle; D004927:Escherichia coli Infections / Q000378:metabolism* / Q000662:veterinary; D007962:Leukocytes / Q000201:enzymology; D008070:Lipopolysaccharides / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000201:enzymology; D008414:Mastitis, Bovine / Q000378:metabolism; D008892:Milk / Q000201:enzymology; D009504:Neutrophils / Q000201:enzymology
D008070:Lipopolysaccharides; D002265:Carboxylic Ester Hydrolases; C048964:acyloxyacyl hydrolase