title: Plasma and synovial fluid microRNAs as potential biomarkers of rheumatoid arthritis and osteoarthritis.
abstract: BACKGROUND
  MicroRNAs (miRNAs), endogenous small noncoding RNAs regulating the activities of target mRNAs and cellular processes, are present in human plasma in a stable form. In this study, we investigated whether miRNAs are also stably present in synovial fluids and whether plasma and synovial fluid miRNAs could be biomarkers of rheumatoid arthritis (RA) and osteoarthritis (OA).
  
  
  METHODS
  We measured concentrations of miR-16, miR-132, miR-146a, miR-155 and miR-223 in synovial fluid from patients with RA and OA, and those in plasma from RA, OA and healthy controls (HCs) by quantitative reverse transcription-polymerase chain reaction. Furthermore, miRNAs in the conditioned medium of synovial tissues, monolayer fibroblast-like synoviocytes, and mononuclear cells were examined. Correlations between miRNAs and biomarkers or disease activities of RA were statistically examined.
  
  
  RESULTS
  Synovial fluid miRNAs were present and as stable as plasma miRNAs for storage at -20 degrees C and freeze-thawing from -20 degrees C to 4 degrees C. In RA and OA, synovial fluid concentrations of miR-16, miR-132, miR-146a, and miR-223 were significantly lower than their plasma concentrations, and there were no correlation between plasma and synovial fluid miRNAs. Interestingly, synovial tissues, fibroblast-like synoviocytes, and mononuclear cells secreted miRNAs in distinct patterns. The expression patterns of miRNAs in synovial fluid of OA were similar to miRNAs secreted by synovial tissues. Synovial fluid miRNAs of RA were likely to originate from synovial tissues and infiltrating cells. Plasma miR-132 of HC was significantly higher than that of RA or OA with high diagnosability. Synovial fluid concentrations of miR-16, miR-146a miR-155 and miR-223 of RA were significantly higher than those of OA. Plasma miRNAs or ratio of synovial fluid miRNAs to plasma miRNAs, including miR-16 and miR-146a, significantly correlated with tender joint counts and 28-joint Disease Activity Score.
  
  
  CONCLUSIONS
  Plasma miRNAs had distinct patterns from synovial fluid miRNAs, which appeared to originate from synovial tissue. Plasma miR-132 well differentiated HCs from patients with RA or OA, while synovial fluid miRNAs differentiated RA and OA. Furthermore, plasma miRNAs correlated with the disease activities of RA. Thus, synovial fluid and plasma miRNAs have potential as diagnostic biomarkers for RA and OA and as a tool for the analysis of their pathogenesis.
authors.affiliation: Department of Orthopaedic Surgery, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo, Kyoto 606-8507, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Murata
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yoshitomi
authors.forename: Shimei
authors.initials: S
authors.lastname: Tanida
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ishikawa
authors.forename: Kohei
authors.initials: K
authors.lastname: Nishitani
authors.forename: Hiromu
authors.initials: H
authors.lastname: Ito
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000175:diagnosis* / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000378:metabolism*; D008875:Middle Aged; D010003:Osteoarthritis / Q000175:diagnosis* / Q000378:metabolism*; D012720:Severity of Illness Index; D013582:Synovial Fluid / Q000378:metabolism*; D013583:Synovial Membrane / Q000378:metabolism
chemical_list: D015415:Biomarkers; D035683:MicroRNAs; C547077:MIRN132 microRNA, human; C542542:MIRN146 microRNA, human; C524942:MIRN155 microRNA, human; C505362:MIRN16 microRNA, human; C525067:MIR223, human
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