title: Anti-inflammatory effects of N-acylethanolamines in rheumatoid arthritis synovial cells are mediated by TRPV1 and TRPA1 in a COX-2 dependent manner.
abstract: BACKGROUND
  The endocannabinoid system modulates function of immune cells and mesenchymal cells such as fibroblasts, which contribute to cartilage destruction in rheumatoid arthritis (RA). The aim of the study was to determine the influence of N-acylethanolamines anandamide (AEA), palmitoylethanolamine (PEA) and oleylethanolamine (OEA) on several features of arthritic inflammation in vitro (human material) and in vivo (a mouse model).
  
  
  METHODS
  Immunofluorescence and western blotting were used to detect cannabinoid receptors and related enzymes. Cytokines and MMP-3 were measured by ELISA. Intracellular signaling proteins were detected by proteome profiling. Proliferation was quantified by CTB reagent. Adhesion was assessed by the xCELLigence system. After onset of collagen type II arthritis, mice were treated daily with the FAAH inhibitor JNJ1661010 (20 mg/kg) or vehicle.
  
  
  RESULTS
  IL-6, IL-8 and MMP-3 (determined only in synovial fibroblasts (SFs)) were downregulated in primary synoviocytes and SFs of RA and OA after AEA, PEA and OEA treatment. In SFs, this was due to activation of TRPV1 and TRPA1 in a COX-2-dependent fashion. FAAH inhibition increased the efficacy of AEA in primary synoviocytes but not in SFs. The effects of OEA and PEA on SFs were diminished by FAAH inhibition. Adhesion to fibronectin was increased in a CB1-dependent manner by AEA in OASFs. Furthermore, elevation of endocannabinoids ameliorated collagen-induced arthritis in mice.
  
  
  CONCLUSIONS
  N-acylethanolamines exert anti-inflammatory effects in SFs. A dual FAAH/COX-2 inhibitor, increasing N-acylethanolamine levels with concomitant TRP channel desensitization, might be a good candidate to inhibit the production of proinflammatory mediators of synovial cells and to reduce erosions.
authors.affiliation: Laboratory of Experimental Rheumatology and Neuroendocrine Immunology, Department of Internal Medicine I, University Hospital Regensburg, Franz Josef Strauss Allee 11, 93042, Regensburg, Germany. torsten.lowin@ukr.de.
authors.forename: Torsten
authors.initials: T
authors.lastname: Lowin
authors.affiliation: Laboratory of Experimental Rheumatology and Neuroendocrine Immunology, Department of Internal Medicine I, University Hospital Regensburg, Franz Josef Strauss Allee 11, 93042, Regensburg, Germany. apitzmart@gmail.com.
authors.forename: Martin
authors.initials: M
authors.lastname: Apitz
authors.affiliation: Department of Orthopaedic Surgery, University Hospital Regensburg, Asklepios Clinic Bad Abbach, Kaiser Karl V Allee 3, 93077, Bad Abbach, Germany. s.anders@asklepios.com.
authors.forename: Sven
authors.initials: S
authors.lastname: Anders
authors.affiliation: Laboratory of Experimental Rheumatology and Neuroendocrine Immunology, Department of Internal Medicine I, University Hospital Regensburg, Franz Josef Strauss Allee 11, 93042, Regensburg, Germany. rainer.straub@ukr.de.
authors.forename: Rainer H
authors.initials: RH
authors.lastname: Straub
mesh_terms: D000368:Aged; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001172:Arthritis, Rheumatoid / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology*; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000502:physiology*; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004983:Ethanolamines / Q000494:pharmacology*; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000502:physiology*; D013583:Synovial Membrane / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000074025:TRPA1 Cation Channel; D050916:TRPV Cation Channels / Q000502:physiology*; D050051:Transient Receptor Potential Channels / Q000502:physiology*
chemical_list: D000893:Anti-Inflammatory Agents; D015220:Calcium Channels; D052246:Cyclooxygenase 2 Inhibitors; D004983:Ethanolamines; D018836:Inflammation Mediators; C022203:N-acylethanolamines; D009419:Nerve Tissue Proteins; D000074025:TRPA1 Cation Channel; C473350:TRPA1 protein, human; D050916:TRPV Cation Channels; C494482:TRPV1 protein, human; D050051:Transient Receptor Potential Channels; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human