Generation mechanism of RANKL+ effector memory B cells: Relevance to the pathogenesis of rheumatoid arthritis

Yuri Ota, Hiroaki Niiro, Shun ichiro Ota, Naoko Ueki, Hirofumi Tsuzuki, Tsuyoshi Nakayama, Koji Mishima, Kazuhiko Higashioka, Siamak Jabbarzadeh-Tabrizi, Hiroki Mitoma, Mitsuteru Akahoshi, Yojiro Arinobu, Akiko Kukita, Hisakata Yamada, Hiroshi Tsukamoto, Koichi Akashi

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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.

Original languageEnglish
Article number67
JournalArthritis Research and Therapy
Volume18
Issue number1
DOIs
Publication statusPublished - Mar 16 2016

All Science Journal Classification (ASJC) codes

  • Rheumatology
  • Immunology and Allergy
  • Immunology

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    Ota, Y., Niiro, H., Ota, S. I., Ueki, N., Tsuzuki, H., Nakayama, T., Mishima, K., Higashioka, K., Jabbarzadeh-Tabrizi, S., Mitoma, H., Akahoshi, M., Arinobu, Y., Kukita, A., Yamada, H., Tsukamoto, H., & Akashi, K. (2016). Generation mechanism of RANKL+ effector memory B cells: Relevance to the pathogenesis of rheumatoid arthritis. Arthritis Research and Therapy, 18(1), [67]. https://doi.org/10.1186/s13075-016-0957-6