Introduction Structural reorganisation of the synovium with expansion of fibroblast-like synoviocytes (FLS) and influx of immune cells is a hallmark of rheumatoid arthritis (RA). Activated FLS are increasingly recognised as a critical component driving synovial tissue remodelling by interacting with immune cells resulting in distinct synovial pathotypes of RA.
Methods Automated high-content fluorescence microscopy of co-cultured cytokine-activated FLS and autologous peripheral CD4+ T cells from patients with RA was established to quantify cell–cell interactions. Phenotypic profiling of cytokine-treated FLS and co-cultured T cells was done by flow cytometry and RNA-Seq, which were integrated with publicly available transcriptomic data from patients with different histological synovial pathotypes. Computational prediction and knock-down experiments were performed in FLS to identify adhesion molecules for cell–cell interaction.
Results Cytokine stimulation, especially with TNF-α, led to enhanced FLS-T cell interaction resulting in cell-cell contact-dependent activation, proliferation and differentiation of T cells. Signatures of cytokine-activated FLS were significantly enriched in RA synovial tissues defined as lymphoid-rich or leucocyte-rich pathotypes, with the most prominent effects for TNF-α. FLS cytokine signatures correlated with the number of infiltrating CD4+ T cells in synovial tissue of patients with RA. Ligand-receptor pair interaction analysis identified ICAM1 on FLS as an important mediator in TNF-mediated FLS-T cell interaction. Both, ICAM1 and its receptors were overexpressed in TNF-treated FLS and co-cultured T cells. Knock-down of ICAM1 in FLS resulted in reduced TNF-mediated FLS-T cell interaction.
Conclusion Our study highlights the role of cytokine-activated FLS in orchestrating inflammation-associated synovial pathotypes providing novel insights into disease mechanisms of RA.
- Rheumatoid Arthritis
- T-Lymphocyte subsets
Data availability statement
Data are available on reasonable request. RNA-Seq data are available upon request. Please contact email@example.com
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MK and MD are joint first authors.
AT, TK and MB are joint senior authors.
Handling editor David S Pisetsky
MK and MD contributed equally.
AT, TK and MB contributed equally.
Contributors All authors contributed to manuscript preparation. MK, MD, AT, FK, LM, LXH, TP, ES, LG, SW, HPK, TK and MB contributed to experimental design of the study. MK, AT and MD contributed to data analysis. MK and MD performed cellular assays. MK, AT, TK and MB drafted the primary manuscript. SEP, TK and MB contributed to patient recruitment. CP, MJL, LES, MF and WW contributed to the revision of this study. GS-F, JSS, DA, GS, CP and MJL provided expertise and contributed to manuscript finalisation. MK and MD contributed equally as co-first authors in the revised manuscript. AT, TK and MB contributed equally and are co-last authors. MB is responsible for the overall content as the guarantor of this manuscript.
Competing interests MB reports about personal fees from Eli-Lilly and received grants from Galapagos, DA received grants and consulting fees from AbbVie, Amgen, Lilly, Merck, Novartis, Pfizer, Roche and Sandoz
and is an editorial board member of Annals of the Rheumatic Diseases, JSS reports about grants, consulting and personal fees from AbbVie, Astra-Zeneca, Lilly, Novartis, Amgen, Astro, Bristol-Myers Squibb, Celgene, Celltrion, Chugai, Gilead, ILTOO, Janssen, Merck Sharp & Dohme, Novartis-Sandoz, Pfizer, Roche, Samsung and UCB and is editor-in-chief of Annals of the Rheumatic Diseases. ES reports speaker fees from Eli-Lilly and supports for attendance of meetings from Pfizer, Bristol-Myers Squibb, Boehringer Ingelheim and Astra Zeneca. CP and is an editorial board member of Annals of the Rheumatic Diseases. The authors CP and MJL are named inventors on a patent application (no. GB 2100821.4), submitted by Queen Mary University of London, that covers methods used to select treatments in rheumatoid arthritis. All other authors declare no competing interests.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.
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