Activated human B cells induce inflammatory fibroblasts with cartilage-destructive properties and become functionally suppressed in return

Hannah Störch, Birgit Zimmermann, Bastian Resch, Lars Oliver Tykocinski, Babak Moradi, Patrick Horn, Ziya Kaya, Norbert Blank, Stefan Rehart, Marc Thomsen, Hanns Martin Lorenz, Elena Neumann, Theresa Tretter

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Background: Cross-talk between synovial fibroblasts (SF) and immune cells is suggested to play a crucial role in inflammation and chronification of rheumatoid arthritis (RA). The contribution of B cells in this process is poorly defined. Methods: Here, primary B cells from healthy donors were polyclonally activated and cocultured with SF of non-synovitic origin from patients with osteoarthritis. Results: In B-SF cocultures the concentrations of interleukin 6 (IL-6) and IL-8 increased manifold compared with single cultures even under physical separation and remained stable for several days after B-cell removal. Intracellular staining confirmed SF as key producers of IL-6 and IL-8, and B cells as main producers of tumour necrosis factor alpha (TNFα) and IL-1ß. Blocking experiments with a combination of anti-TNFα-antibodies and rIL-1RA significantly reduced SF cytokine production by up to 90%, suggesting that B-cell-derived TNFα and IL-1ß were crucial mediators of SF activation. Interestingly, B-cell cytokine production, CD25 expression and proliferation decreased in cocultures by at least 50%, demonstrating a negative regulatory loop towards the activated B cells. Inhibition of activin receptor-like kinase 5, a crucial component of the tumour growth factor ß (TGFß) signalling pathway, partly restored B-cell proliferation, suggesting a contribution of SF-derived TGFß in B-cell suppression. Besides cytokines, B-cell-activated SF also upregulated secretion of matrix metalloproteases such as MMP-3, thereby acquiring potential tissue destructive properties. This was confirmed by their invasion into human cartilage in the severe combined immunodeficiency mouse fibroblast invasion model in vivo. Conclusions: Interaction with activated B cells leads to conversion of non-arthritic SF into SF with a proinflammatory and aggressive RA-like phenotype, thereby suggesting a new, so far unrecognised role for B cells in RA pathogenesis.

Original languageEnglish
Pages (from-to)924-932
Number of pages9
JournalAnnals of the Rheumatic Diseases
Issue number5
StatePublished - May 2016
Externally publishedYes


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