title: Activation of fibroblast-like synoviocytes derived from rheumatoid arthritis via lysophosphatidic acid-lysophosphatidic acid receptor 1 cascade.
abstract: BACKGROUND
  Lysophosphatidic acid (LPA) is a bioactive lipid that binds to G protein-coupled receptors (LPA1-6). Recently, we reported that abrogation of LPA receptor 1 (LPA1) ameliorated murine collagen-induced arthritis, probably via inhibition of inflammatory cell migration, Th17 differentiation and osteoclastogenesis. In this study, we examined the importance of the LPA-LPA1 axis in cell proliferation, cytokine/chemokine production and lymphocyte transmigration in fibroblast-like synoviocytes (FLSs) obtained from the synovial tissues of rheumatoid arthritis (RA) patients.
  
  
  METHODS
  FLSs were prepared from synovial tissues of RA patients. Expression of LPA1-6 was examined by quantitative real-time RT-PCR. Cell surface LPA1 expression was analyzed by flow cytometry. Cell proliferation was analyzed using a cell-counting kit. Production of interleukin 6 (IL-6), vascular endothelial growth factor (VEGF), chemokine (C-C motif) ligand 2 (CCL2), metalloproteinase 3 (MMP-3) and chemokine (C-X-C motif) ligand 12 (CXCL12) was measured by enzyme-linked immunosorbent assay. Pseudoemperipolesis was evaluated using a coculture of RA FLSs and T or B cells. Cell motility was examined by scrape motility assay. Expression of adhesion molecules was determined by flow cytometry.
  
  
  RESULTS
  The expression of LPA1 mRNA and cell surface LPA1 was higher in RA FLSs than in FLSs from osteoarthritis tissue. Stimulation with LPA enhanced the proliferation of RA FLSs and the production of IL-6, VEGF, CCL2 and MMP-3 by FLSs, which were suppressed by an LPA1 inhibitor (LA-01). Ki16425, another LPA1 antagonist, also suppressed IL-6 production by LPA-stimulated RA FLSs. However, the production of CXCL12 was not altered by stimulation with LPA. LPA induced the pseudoemperipolesis of T and B cells cocultured with RA FLSs, which was suppressed by LPA1 inhibition. In addition, LPA enhanced the migration of RA FLSs and expression of vascular cell adhesion molecule and intercellular adhesion molecule on RA FLSs, which were also inhibited by an LPA1 antagonist.
  
  
  CONCLUSIONS
  Collectively, these results indicate that LPA-LPA1 signaling contributes to the activation of RA FLSs.
authors.forename: Yoshishige
authors.initials: Y
authors.lastname: Miyabe
authors.forename: Chie
authors.initials: C
authors.lastname: Miyabe
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Iwai
authors.forename: Waka
authors.initials: W
authors.lastname: Yokoyama
authors.forename: Chiyoko
authors.initials: C
authors.lastname: Sekine
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Sugimoto
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Harigai
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miyasaka
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Miyasaka
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Nanki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001172:Arthritis, Rheumatoid / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D016466:CHO Cells; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D016207:Cytokines / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D007555:Isoxazoles / Q000494:pharmacology; D007962:Leukocytes / Q000187:drug effects; D008246:Lysophospholipids / Q000494:pharmacology*; D008875:Middle Aged; D011422:Propionates / Q000494:pharmacology; D049368:Receptors, Lysophosphatidic Acid / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013583:Synovial Membrane / Q000378:metabolism* / Q000473:pathology
chemical_list: C477898:3-(4-(4-((1-(2-chlorophenyl)ethoxy)carbonyl amino)-3-methyl-5-isoxazolyl) benzylsulfanyl) propanoic acid; D016207:Cytokines; D018836:Inflammation Mediators; D007555:Isoxazoles; D008246:Lysophospholipids; D011422:Propionates; D049368:Receptors, Lysophosphatidic Acid; C032881:lysophosphatidic acid