[Effect of lipopolysaccharide of Porphyromonas gingivalis on prostaglandin E2 biosynthetic pathway in human monocytic cell strain THP-1].
OBJECTIVE
To investigate the effect of lipopolysaccharide of Porphyromonas gingivalis (Pg-LPS) on the bio-thythetic pathway of prostaglandin E2 (PGE2) and its difference from lipopolysaccharide of Escherichia coli (Ec-LPS).


METHODS
Purified Pg-LPS and Ec-LPS were used to stimulate a human monocytic cell strain THP-1. PGE2 concentration was determined by an enzyme immunoassay kit. The release of tritium labeled arachidonic acid (AA) was detected by a liquid scintillation counter. Reverse transcription polymerase chain reaction and western blot were used to analyse the expression of cytosolic phospholipase A2 (cPLA2) enzyme, cyclooxygenase-2 (COX-2), and microsomal prostaglandin E synthase-1 (mPGES-1).


RESULTS
The effect of Pg-LPS on induction of PGE2 and release of AA was significantly weaker than that of Ec-LPS (P < 0.05).Increased secretion of PGE2 was observed after stimulation with Pg-LPS for 6 h, which peak at 24 h at (221.40 +/- 29.46) ng/L; or with Ec-LPS for 1-48 h, at (161.80 +/- 17.31) approximately (379.80 +/- 37.35) ng/L. The highest levels of COX-2 and mPGES-1 were shown after 16 h treatment by Pg-LPS, or after 8 h and 16 h by Ec-LPS respectively.cPLA2 inhibitor AACOCF3 could lower the level of LPS-induced release of AA, while it did not influence the production of PGE2. COX-2 inhibitor NS-398 could remarkably reduce the concentration of PGE2.


CONCLUSIONS
Pg-LPS showed delayed and weaker effect on PGE2 biosynthetic pathway than Ec-LPS. Pg-LPS-induced PGE2 synthesis was mainly due to enhanced expression of COX-2 and mPGES-1, whereas cPLA2 played an insignificant role.
Wu
Yan-min
YM
Department of Stomatology, The Second Affiliated Hospital of Medical School of Zhejiang University, Hangzhou 310009, China.
Chen
Li-li
LL
Sun
Wei-lian
WL
Yan
Jie
J
D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000378:metabolism; D015232:Dinoprostone / Q000096:biosynthesis*; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism*; D016966:Porphyromonas gingivalis; D000071876:Prostaglandin-E Synthases
D008070:Lipopolysaccharides; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D019746:Intramolecular Oxidoreductases; C000605862:PTGES protein, human; D000071876:Prostaglandin-E Synthases; D015232:Dinoprostone