Arginase activity in a murine macrophage cell line (RAW264.7) stimulated with lipopolysaccharide from Actinobacillus actinomycetemcomitans.
OBJECTIVE
The aim of the present study was to determine whether or not lipopolysaccharide from Actinobacillus actinomycetemcomitans could stimulate arginase activity in a murine macrophage cell line (RAW264.7 cells).


METHODS
RAW264.7 cells were treated with A. actinomycetemcomitans-lipopolysaccharide or lipopolysaccharide from Escherichia coli for 24 h. The effect of polymyxin B, l-norvaline, dl-norvaline, dexamethasone and cytokines (interferon-gamma and interleukin-4) on arginase activity in A. actinomycetemcomitans-lipopolysaccharide-stimulated cells was also determined. The cells were pretreated with anti-CD14, anti -toll-like receptor 2, or anti-toll-like receptor 4 antibody prior to stimulation with A. actinomycetemcomitans-lipopolysaccharide. Arginase activity was determined by a colorimetric assay.


RESULTS
A. actinomycetemcomitans-lipopolysaccharide stimulated arginase activity in RAW264.7 cells in a dose-dependent manner, but was less potent than E. coli-lipopolysaccharide. Polymyxin B and l-norvaline, but not dl-norvaline, blocked the arginase activity in A. actinomycetemcomitans-lipopolysaccharide-stimulated cells. Dexamethasone and interleukin-4 but not interferon-gamma augmented arginase activity in A. actinomycetemcomitans-lipopolysaccharide-stimulated cells. Treatment of the cells with anti-CD14 and anti-toll-like receptor 4 but not anti-toll-like receptor 2 antibody decreased arginase activity in A. actinomycetemcomitans-lipopolysaccharide-stimulated cells.


CONCLUSIONS
The results of the present study suggest that lipopolysaccharide from A. actinomycetemcomitans via CD14/toll-like receptor 4 complex molecules and the regulatory control of glucocorticoid and cytokines may stimulate arginase activity in RAW264.7 cells.
Sosroseno
W
W
Department of Oral Biology, School of Dental Sciences, University Sains Malaysia, Kota Bharu, Malaysia. wihaskoro@kb.usm.my
Musa
M
M
Ravichandran
M
M
Fikri Ibrahim
M
M
Bird
P S
PS
Seymour
G J
GJ
D016976:Aggregatibacter actinomycetemcomitans / Q000502:physiology*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001119:Arginase / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D002460:Cell Line; D016207:Cytokines / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology; D018950:Lipopolysaccharide Receptors / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000276:immunology; D008264:Macrophages / Q000201:enzymology*; D051379:Mice; D011112:Polymyxin B / Q000494:pharmacology; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D016207:Cytokines; D005938:Glucocorticoids; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D003907:Dexamethasone; C005313:norvaline; D001119:Arginase; D014633:Valine; D011112:Polymyxin B