title: Interleukin-17A expression in human synovial mast cells in rheumatoid arthritis and osteoarthritis.
abstract: BACKGROUND
  Interleukin (IL)-17A plays a pivotal role in the pathogenesis of rheumatoid arthritis (RA). The expression of IL-17A in synovial mast cells (MCs) in RA and osteoarthritis (OA) has been reported, but the frequencies of IL-17A expression in synovial MCs have varied. The aim of this study was to investigate whether IL-17A expression is upregulated in human synovial MCs in RA and to elucidate the mechanism of IL-17A expression in synovial MCs.
  
  
  METHODS
  Synovial tissues were obtained from patients with RA or OA undergoing joint replacement surgery, and synovial MCs were enzymatically dispersed. Synovium-derived cultured MCs were generated by culturing synovial cells with stem cell factor. IL-17A expression was investigated using immunofluorescence in synovial tissues. IL-17A mRNA expression and its production from MCs were examined using RT-PCR and ELISA, respectively.
  
  
  RESULTS
  The number of IL-17A-positive ((+)) synovial MCs and the percentage of IL-17A(+) MCs among all the IL-17A(+) cells from RA patients were not significantly increased compared with those from OA subjects. The synovium-derived cultured MCs spontaneously released small amounts of IL-17A. Neither IgE- nor IgG-dependent stimulation increased IL-17A production from the MCs. IL-33, tumor necrosis factor-α, C5a, lipopolysaccharide or IL-23 plus IL-1β did not affect IL-17A production in MCs.
  
  
  CONCLUSIONS
  The synovial MCs are not a main source of IL-17A in RA.
authors.affiliation: Allergy and Immunology Project Team, Nihon University School of Medicine, Tokyo, Japan; Department of Orthopaedic Surgery, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Jun-Ichiro
authors.initials: J
authors.lastname: Kan
authors.affiliation: Allergy and Immunology Project Team, Nihon University School of Medicine, Tokyo, Japan; Department of Orthopaedic Surgery, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Mishima
authors.affiliation: Allergy and Immunology Project Team, Nihon University School of Medicine, Tokyo, Japan; Laboratory for Allergic Disease, RCAI, RIKEN Center for Integrative Medical Sciences (IMS-RCAI), Yokohama, Japan; Division of Medical Education Planning and Development, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Kashiwakura
authors.affiliation: Allergy and Immunology Project Team, Nihon University School of Medicine, Tokyo, Japan; Division of Medical Education Planning and Development, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Sasaki-Sakamoto
authors.affiliation: Department of Orthopaedic Surgery, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Seki
authors.affiliation: Department of Orthopaedic Surgery, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Shu
authors.initials: S
authors.lastname: Saito
authors.affiliation: Department of Microbiology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Chisei
authors.initials: C
authors.lastname: Ra
authors.affiliation: Department of Orthopaedic Surgery, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Tokuhashi
authors.affiliation: Allergy and Immunology Project Team, Nihon University School of Medicine, Tokyo, Japan; Division of Medical Education Planning and Development, Nihon University School of Medicine, Tokyo, Japan. Electronic address: okayama.yoshimichi@nihon-u.ac.jp.
authors.forename: Yoshimichi
authors.initials: Y
authors.lastname: Okayama
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000235:genetics* / Q000276:immunology / Q000601:surgery; D015415:Biomarkers; D002478:Cells, Cultured; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006801:Humans; D020381:Interleukin-17 / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008407:Mast Cells / Q000276:immunology / Q000378:metabolism*; D010003:Osteoarthritis / Q000175:diagnosis / Q000235:genetics* / Q000276:immunology / Q000601:surgery; D000070918:Synoviocytes / Q000276:immunology / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D016207:Cytokines; D020381:Interleukin-17
keywords: Arthritis; Human mast cells; Interleukin-17; Osteoarthritis; Rheumatoid