title: Expression of microRNA-146 in rheumatoid arthritis synovial tissue.
abstract: OBJECTIVE
  Several microRNA, which are approximately 22-nucleotide noncoding RNAs, exhibit tissue-specific or developmental stage-specific expression patterns and are associated with human diseases. The objective of this study was to identify the expression pattern of microRNA-146 (miR-146) in synovial tissue from patients with rheumatoid arthritis (RA).
  
  
  METHODS
  The expression of miR-146 in synovial tissue from 5 patients with RA, 5 patients with osteoarthritis (OA), and 1 normal subject was analyzed by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and by in situ hybridization and immunohistochemistry of tissue sections. Induction of miR-146 following stimulation with tumor necrosis factor alpha (TNFalpha) and interleukin-1beta (IL-1beta) of cultures of human rheumatoid arthritis synovial fibroblasts (RASFs) was examined by quantitative PCR and RT-PCR.
  
  
  RESULTS
  Mature miR-146a and primary miR-146a/b were highly expressed in RA synovial tissue, which also expressed TNFalpha, but the 2 microRNA were less highly expressed in OA and normal synovial tissue. In situ hybridization showed primary miR-146a expression in cells of the superficial and sublining layers in synovial tissue from RA patients. Cells positive for miR-146a were primarily CD68+ macrophages, but included several CD3+ T cell subsets and CD79a+ B cells. Expression of miR-146a/b was markedly up-regulated in RASFs after stimulation with TNFalpha and IL-1beta.
  
  
  CONCLUSIONS
  This study shows that miR-146 is expressed in RA synovial tissue and that its expression is induced by stimulation with TNFalpha and IL-1beta. Further studies are required to elucidate the function of miR-146 in these tissues.
authors.affiliation: National Research Institute for Child Health and Development, Tokyo, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Nakasa
authors.forename: Shigeru
authors.initials: S
authors.lastname: Miyaki
authors.forename: Atsuko
authors.initials: A
authors.lastname: Okubo
authors.forename: Megumi
authors.initials: M
authors.lastname: Hashimoto
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Nishida
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Ochi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Asahara
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000096:biosynthesis*; D008875:Middle Aged; D013583:Synovial Membrane / Q000378:metabolism*
chemical_list: D035683:MicroRNAs