title: Generation mechanism of RANKL(+) effector memory B cells: relevance to the pathogenesis of rheumatoid arthritis.
abstract: BACKGROUND
  The efficacy of B cell-depleting therapies for rheumatoid arthritis underscores antibody-independent functions of effector B cells such as cognate T-B interactions and production of pro-inflammatory cytokines. Receptor activator of nuclear factor κB ligand (RANKL) is a key cytokine involved in bone destruction and is highly expressed in synovial fluid B cells in patients with rheumatoid arthritis. In this study we sought to clarify the generation mechanism of RANKL(+) effector B cells and their impacts on osteoclast differentiation.
  
  
  METHODS
  Peripheral blood and synovial fluid B cells from healthy controls and patients with rheumatoid arthritis were isolated using cell sorter. mRNA expression of RANKL, osteoprotegerin, tumor necrosis factor (TNF)-α, and Blimp-1 was analyzed by quantitative real-time polymerase chain reaction. Levels of RANKL, CD80, CD86, and CXCR3 were analyzed using flow cytometry. Functional analysis of osteoclastogenesis was carried out in the co-culture system using macrophage RAW264 reporter cells.
  
  
  RESULTS
  RANKL expression was accentuated in CD80(+)CD86(+) B cells, a highly activated B-cell subset more abundantly observed in patients with rheumatoid arthritis. Upon activation via B-cell receptor and CD40, switched-memory B cells predominantly expressed RANKL, which was further augmented by interferon-γ (IFN-γ) but suppressed by interleukin-21. Strikingly, IFN-γ also enhanced TNF-α expression, while it strongly suppressed osteoprotegerin expression in B cells. IFN-γ increased the generation of CXCR3(+)RANKL(+) effector B cells, mimicking the synovial B cell phenotype in patients with rheumatoid arthritis. Finally, RANKL(+) effector B cells in concert with TNF-α facilitated osteoclast differentiation in vitro.
  
  
  CONCLUSIONS
  Our current findings have shed light on the generation mechanism of pathogenic RANKL(+) effector B cells that would be an ideal therapeutic target for rheumatoid arthritis in the future.
authors.affiliation: Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Ota
authors.affiliation: Clinical Education Center, Kyushu University Hospital, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan. hniiro@med.kyushu-u.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Niiro
authors.affiliation: Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Shun-Ichiro
authors.initials: S
authors.lastname: Ota
authors.affiliation: Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Ueki
authors.affiliation: Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Tsuzuki
authors.affiliation: Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Nakayama
authors.affiliation: Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Mishima
authors.affiliation: Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Higashioka
authors.affiliation: Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Siamak
authors.initials: S
authors.lastname: Jabbarzadeh-Tabrizi
authors.affiliation: Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Mitoma
authors.affiliation: Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Mitsuteru
authors.initials: M
authors.lastname: Akahoshi
authors.affiliation: Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Yojiro
authors.initials: Y
authors.lastname: Arinobu
authors.affiliation: Department of Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Kukita
authors.affiliation: Division of Host Defense, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Hisakata
authors.initials: H
authors.lastname: Yamada
authors.affiliation: Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsukamoto
authors.affiliation: Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Akashi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D002454:Cell Differentiation / Q000502:physiology; D002469:Cell Separation; D018920:Coculture Techniques; D005260:Female; D006801:Humans; D007156:Immunologic Memory / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010010:Osteoclasts / Q000166:cytology; D053245:RANK Ligand / Q000276:immunology*; D060888:Real-Time Polymerase Chain Reaction; D055815:Young Adult
chemical_list: D053245:RANK Ligand; C505688:TNFSF11 protein, human
keywords: B cells; RANKL; Rheumatoid arthritis