Crystal-induced neutrophil activation. II. Evidence for the activation of a phosphatidylcholine-specific phospholipase D.
OBJECTIVE
To investigate the involvement of phospholipase D in the signaling pathways activated by 2 pathologically relevant inflammatory microcrystals, monosodium urate (MSU) and calcium pyrophosphate dihydrate (CPPD).


METHODS
Human peripheral blood neutrophils were used throughout. Phospholipase D activity was monitored by measuring 3 separate indices: 1) the mass of phosphatidic acid, 2) the levels of alkyl-phosphatidic acid, and 3) the levels of formation, in the presence of ethanol, of phosphatidylethanol. The latter 2 parameters were measured in cells labeled with 1-0-3H-alkyl-2-acetyl-sn-glycero-3-phosphocholine. The cells were stimulated with microcrystals of triclinic morphology.


RESULTS
Both MSU and CPPD crystals induced a time- and concentration-dependent accumulation of phosphatidic acid mass and elevation in levels of alkyl-phosphatidic acid and phosphatidylethanol in prelabeled cells. The activation of phospholipase D by the microcrystals was partially sensitive to colchicine and largely resistant to pertussis toxin. Inhibition of phosphatidic acid formation by wortmannin or ethanol reduced the microcrystal-stimulated production of superoxide anions.


CONCLUSIONS
These results indicate that microcrystals stimulate phospholipase D in human neutrophils and that at least some of the functional consequences of neutrophil-microcrystal interactions may be dependent on this biochemical pathway.
Centre de Recherche en Inflammation, Immunologie et Rhumatologie, CHUL, Ste.-Foy, Quebec, Canada.
P H
PH
Naccache
S
S
Bourgoin
E
E
Plante
C J
CJ
Roberge
R
R
de Medicis
A
A
Lussier
P E
PE
Poubelle
D000730:Androstadienes / Q000494:pharmacology; D002131:Calcium Pyrophosphate / Q000494:pharmacology; D003078:Colchicine / Q000494:pharmacology; D003460:Crystallization; D004789:Enzyme Activation; D000431:Ethanol / Q000494:pharmacology; D020404:Glycerophospholipids; D006801:Humans; D006868:Hydrolysis; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D037342:Pertussis Toxin; D010712:Phosphatidic Acids / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D014527:Uric Acid / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D000077191:Wortmannin
D000730:Androstadienes; D020404:Glycerophospholipids; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D010566:Virulence Factors, Bordetella; C051521:phosphatidylethanol; D013481:Superoxides; D014527:Uric Acid; D000431:Ethanol; D037342:Pertussis Toxin; D010739:Phospholipase D; D003078:Colchicine; D002131:Calcium Pyrophosphate; D000077191:Wortmannin