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Immune regulation
03.23 Transcriptomic analysis of plasmacytoid dendritic cells from rheumatoid arthritis patients reveals novel targets for therapy
  1. Garyfalia Papadaki1,
  2. Panagiota Goutakoli1,
  3. Joachim R Grün2,
  4. Andreas Grützkau2,
  5. Antonios Fanouriakis3,
  6. George A Pavlopoulos4,
  7. Ioannis Iliopoulos4,
  8. George Bertsias1,
  9. Dimitrios Boumpas5,
  10. Prodromos Sidiropoulos1,3,*,
  11. Panayotis Verginis6,*
  1. 1Laboratory of Autoimmunity and Inflammation, University of Crete, Medical School, Heraklion, Greece
  2. 2Deutsches Rheuma-Forschungszentrum, a Leibniz Institute, Berlin, Germany
  3. 3Department of Rheumatology, University of Crete, Medical School, Heraklion, Greece
  4. 4Division of Basic Sciences, University of Crete, Medical School, Gouves, Heraklion, Crete, Greece
  5. 54th Department of Medicine– Attikon University Hospital; Joint Academic Rheumatology Program, National and Kapodestrian University of Athens, Greece
  6. 6Division of Immunobiology, Biomedical Research Foundation Academy of Athens, Athens, Greece
  7. *Equal contribution

Abstract

Background/objectives Reestablishing immune tolerance and long term suppression represent major therapeutic goals in rheumatoid arthritis (RA). Our laboratory previously demonstrated that plasmacytoid dendritic cells (pDCs) from RA patients in remission have the ability to induce IL-10 producing regulatory T cells (Tregs) in vitro. However the molecular mechanism of RA pDC-mediated Treg induction remains elusive. Herein, we sought to identify novel targets of RA pDCs that contributes to the induction of tolerance and might lead to remission.

Materials/methods pDCs were isolated from peripheral blood of RA patients responding to anti-TNF therapy (remission based on disease activity score DAS28 <5.1) and healthy control subjects and DNA microarrays were performed. Flow cytometry and real time PCR were used to verify the expression of de-regulated genes in pDCs. Finally, in vitro cultures of pDCs activated with CpG B were performed to assess the functional importance of these gene signatures.

Results pDCs from RA patients (n=5) exhibited a differential gene signature (6741 deregulated genes) compared to pDCs from healthy controls (n=5). Notably, IL-6 receptor (IL-6R) gene, exhibited increased expression levels in pDCs isolated from RA patients compared to healthy pDCs. We verified these results using flow cytometry for the surface expression levels of IL-6 receptor in a subsequent cohort of patients responding to therapy (n=3) vs healthy. Moreover, in functional experiments assessing IL-6R activation, coculture of healthy pDCs with CpG B in the presence or absence of recombinant IL-6, revealed that pSTAT3 levels were increased in pDCs cultured in the presence of IL-6. Cytokine expression studies (IFN-α, β, TNF-α, IL-6) are in progress to address the role of pDCs upon IL-6 signalling. The functional importance of the previous findings will be addressed in coculture experiments of IL-6 stimulated pDCs with CD4+CD25- T cells isolated from cord blood and monitor T cell proliferation based on dilution of CFSE staining.

Conclusions We found that pDCs from RA patients in remission display increased IL-6R expression levels and IL-6 signalling pathway is induced in healthy pDCs in the presence of IL-6. This novel finding that may drive pDCs towards a previously described tolerogenic phenotype, need to be further addressed.

https://doi.org/10.1136/annrheumdis-2016-211049.23

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