Cytokine mRNA profiling identifies B cells as a major source of RANKL in rheumatoid arthritis

Lorraine Yeo, Kai-Michael Toellner, M Salmon, Andrew Filer, Christopher Buckley, Karim Raza, Dagmar Scheel-Toellner

Research output: Contribution to journalArticlepeer-review

116 Citations (Scopus)
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OBJECTIVES: In rheumatoid arthritis (RA), a complex cytokine network drives chronic inflammation and joint destruction. So far, few attempts have been made to identify the cellular sources of individual cytokines systematically. Therefore, the primary objective of this study was systematically to assess the cytokine messenger RNA expression profiles in the five largest cell populations in the synovial fluid and peripheral blood of RA patients. To reflect the in vivo situation as closely as possible, the cells were neither cultured nor stimulated ex vivo. METHODS: Inflammatory cells from 12 RA patients were sorted into CD4 and CD8 T cells, B cells, macrophages and neutrophils. mRNA expression for 41 cytokines was determined by real-time PCR using microfluidic cards. Receptor activator nuclear factor kappa B ligand (RANKL) (TNFSF11) expression by B cells was further confirmed by flow cytometry and by immunofluorescence staining of frozen sections of synovial tissue from patients with RA. RESULTS: The detection of cytokines characteristic for T cells and myeloid cells in the expected populations validated this methodology. Beyond the expected cytokine patterns, novel observations were made. Striking among these was the high expression of mRNA for RANKL in B cells from synovial fluid. This observation was validated at the protein level in synovial tissue and fluid. CONCLUSIONS: RANKL, the key cytokine driving bone destruction by osteoclast activation, is produced by synovial B cells in RA. This observation is of importance for our understanding of the role of B cells in RA and their therapeutic targeting.
Original languageEnglish
Pages (from-to)2022-2028
Number of pages7
JournalAnnals of the Rheumatic Diseases
Issue number11
Publication statusPublished - 8 Jul 2011


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