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  • Open Access

Interaction with activated monocytes enhances cytokine expression and suppressive activity of human CD4+CD45RO+CD25+CD127low regulatory T cells

  • 1,
  • 1,
  • 1, 2, 3,
  • 2,
  • 1, 2, 3,
  • 1 and
  • 1
Journal of Translational Medicine201210 (Suppl 3) :P3

https://doi.org/10.1186/1479-5876-10-S3-P3

  • Published:

Keywords

  • Rheumatoid Arthritis
  • Flow Cytometry
  • Synovial Fluid
  • Cytokine Expression
  • Potent Producer

Introduction

Despite the high frequency of CD4+ T cells with a regulatory phenotype (CD25+CD127lowFoxP3+) in the joints of patients with rheumatoid arthritis (RA), inflammation persists. Regulatory T cells (Tregs) can be converted into pro-inflammatory IL-17-producing cells by inflammatory mediators, particularly IL-1β.

Aim

To investigate whether activated monocytes, which are abundantly present in the rheumatic joint and potent producers of IL-1β, induce pro-inflammatory cytokine expression in Tregs and whether this impairs Treg function.

Materials and methods

The presence and phenotype of CD4+CD45RO+CD25+CD127low T cells (memory Tregs) and CD14+ monocytes in the peripheral blood (PB) and synovial fluid (SF) from patients with RA was investigated by flow cytometry. FACS-sorted memory Tregs from healthy controls were co-cultured with autologous in vitro-activated monocytes and anti-CD3 monoclonal antibody. Intracellular cytokine expression, phenotype and function were determined by flow cytometry, ELISA and proliferation assays.

Results

Patients with RA showed higher frequencies of CD4+CD45RO+CD25+CD127low Tregs and activated CD14+ monocytes in SF relative to PB. We demonstrate that activated monocytes induced an increase in the percentage of IL-17+, IFNγ+ and TNF-α+, but also IL-10+ Tregs. Blocking and reconstitution experiments revealed that the observed increase in IL-17+ and IFNγ+ Tregs was driven by monocyte-derived IL-1β, IL-6 and TNF-α and was mediated by both CD14+CD16- and CD14+CD16+ monocyte subsets. Despite enhanced cytokine expression, cells maintained their CD25+FoxP3+CD39+ Treg phenotype and showed enhanced capacity to suppress proliferation and IL-17 production by effector T cells.

Conclusion

Tregs exposed to a pro-inflammatory environment show increased suppressive activity.

Authors’ Affiliations

(1)
Centre for Molecular and Cellular Biology of Inflammation, King’s College London, London, UK
(2)
Dept. Rheumatology, Guy’s & St Thomas’ NHS Foundation Trust, London, UK
(3)
Academic Dept. Rheumatology, King’s College London, London, UK

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