title: Synovial membrane immunohistology in early-untreated rheumatoid arthritis reveals high expression of catabolic bone markers that is modulated by methotrexate.
abstract: BACKGROUND
  We aimed to investigate the expression and therapeutic modulation of the receptor activator of the NF-κB ligand (RANKL) system in early-untreated rheumatoid arthritis (RA).
  
  
  METHODS
  In this study, 15 patients with newly diagnosed RA (median symptom duration 7 months) were started on methotrexate (MTX) 20 mg weekly. Synovial biopsies were obtained by needle arthroscopy at baseline and 8 weeks after initiation of therapy. X-rays of the hands and feet were obtained at baseline and 1 year after diagnosis. Immunohistochemistry was performed to detect RANKL, receptor activator of nuclear factor-κB (RANK) and osteoprotegerin (OPG) in the synovial biopsies. The in vitro effect of MTX was tested on RA-derived primary fibroblasts and the osteoblasts-like osteosarcoma cell line (rtPCR, Western blot and ELISA) and in osteoclasts (tartrate-resistant acid phosphatase staining and dentine pit formation assay).
  
  
  RESULTS
  MTX decreased synovial cellularity as well as RANK expression and the RANKL/OPG ratio. We confirmed this effect by a decrease of the mRNA and protein RANKL/OPG ratio in synovial-derived fibroblasts and osteoblasts-like tumoral cells exposed in vitro to methotrexate. Supernatants from MTX treated osteoblasts-like tumoral cells prevented pre-osteoclast formation in the absence of exogenous RANKL. Furthermore, MTX blocked osteoclastogenesis from peripheral blood mononuclear cells despite the presence of macrophage colony stimulating factor and RANKL, which indicates that MTX directly inhibits osteoclastogenesis.
  
  
  CONCLUSIONS
  The synovial membrane of early-untreated RA is characterized by a high RANKL/OPG ratio that can be reversed by methotrexate.
authors.forename: Shankar
authors.initials: S
authors.lastname: Revu
authors.forename: Petra
authors.initials: P
authors.lastname: Neregård
authors.forename: Erik
authors.initials: E
authors.lastname: af Klint
authors.forename: Marina
authors.initials: M
authors.lastname: Korotkova
authors.forename: Anca Irinel
authors.initials: AI
authors.lastname: Catrina
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D015153:Blotting, Western; D001862:Bone Resorption / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D008297:Male; D008727:Methotrexate / Q000627:therapeutic use*; D008875:Middle Aged; D010010:Osteoclasts / Q000187:drug effects / Q000378:metabolism; D053244:Osteoprotegerin / Q000096:biosynthesis; D053245:RANK Ligand / Q000096:biosynthesis; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013583:Synovial Membrane / Q000187:drug effects / Q000378:metabolism*
chemical_list: D007166:Immunosuppressive Agents; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; C505686:TNFRSF11A protein, human; C505688:TNFSF11 protein, human; D008727:Methotrexate