title: Interleukin-1 beta induces cytosolic phospholipase A2 and prostaglandin H synthase in rheumatoid synovial fibroblasts. Evidence for their roles in the production of prostaglandin E2.
abstract: OBJECTIVE
  In order to investigate potential regulatory mechanisms for the increased production of prostaglandin E2 (PGE2) in interleukin-1 beta (IL-1 beta)-stimulated rheumatoid synovial fibroblasts (RSF), this study examined the induction of phospholipase A2 (PLA2) and prostaglandin H synthase (PGHS) enzymes and the correlation of these events with PGE2 production in IL-1 beta-stimulated RSF.
  
  
  METHODS
  Protein and messenger RNA (mRNA) levels of cytosolic PLA2 (cPLA2) and PGHS-2 enzymes in IL-1 beta-stimulated RSF were measured by Western and Northern blotting, respectively, using specific antisera and complementary DNA probes. Enzymatic activity of cPLA2 was determined in cell-free reaction mixtures utilizing mixed micelles of 14C-phosphatidylcholine and Triton X-100 as the substrate. PGE2 levels were quantitated using a commercial enzyme immunoassay kit.
  
  
  RESULTS
  Incubation of RSF with IL-1 beta increased the mRNA and protein levels for the high molecular weight cPLA2 as well as for the mitogen/growth factor-responsive PGHS (PGHS-2). The IL-1 receptor antagonist completely abolished the induction of these two enzymes and the stimulation of PGE2 production by IL-1 beta in RSF. In contrast, levels of the other known forms of these enzymes, i.e., the 14-kd secretory group II PLA2 (sPLA2) and the constitutive form of PGHS (PGHS-1), were unaffected by IL-1 beta treatment.
  
  
  CONCLUSIONS
  These are the first data to demonstrate the coordinate induction by IL-1 of cPLA2 and PGHS-2 in RSF. The time-course for the induction of these enzymes suggests that their increase contributes to the increased production of PGE2 in IL-1-treated RSF, and may help explain the capacity of RSF to produce large amounts of PGE2.
authors.affiliation: Hoffmann-La Roche, Inc., Nutley, New Jersey.
authors.forename: K I
authors.initials: KI
authors.lastname: Hulkower
authors.forename: S J
authors.initials: SJ
authors.lastname: Wertheimer
authors.forename: W
authors.initials: W
authors.lastname: Levin
authors.forename: J W
authors.initials: JW
authors.lastname: Coffey
authors.forename: C M
authors.initials: CM
authors.lastname: Anderson
authors.forename: T
authors.initials: T
authors.lastname: Chen
authors.forename: D L
authors.initials: DL
authors.lastname: DeWitt
authors.forename: R M
authors.initials: RM
authors.lastname: Crowl
authors.forename: W C
authors.initials: WC
authors.lastname: Hope
authors.forename: D W
authors.initials: DW
authors.lastname: Morgan
mesh_terms: D001172:Arthritis, Rheumatoid / Q000276:immunology / Q000378:metabolism*; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology*; D015232:Dinoprostone / Q000096:biosynthesis*; D005347:Fibroblasts / Q000201:enzymology*; D006801:Humans; D007375:Interleukin-1 / Q000276:immunology*; D010741:Phospholipases A / Q000235:genetics / Q000378:metabolism*; D054467:Phospholipases A2; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D013583:Synovial Membrane / Q000276:immunology / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology
chemical_list: D007375:Interleukin-1; D012333:RNA, Messenger; D011451:Prostaglandin-Endoperoxide Synthases; D010741:Phospholipases A; D054467:Phospholipases A2; D015232:Dinoprostone