TBA (19A156)

CD209+/CD14+ dendritic cells characterization in rheumatoid vs psoriasis arthritis

Author(s)

Marzaioli Viviana, Floudas Achilleas, Wade Siobhán, Murray Kieran, Veale Douglas J., Fearon Ursula

Department(s)/Institutions

Molecular Rheumatology, Trinity College Dublin Department of Rheumatology, St. Vincent’s University Hospital, Dublin, Ireland

Introduction

Dendritic cells (DCs) are a heterogeneous population of professional antigen-presenting cells which are at the interface between innate and adaptive immunity. There are different DCs subsets which are classified according to their tissue location and their functions. A specific subset of DCs is known to derive from monocyte and have a key role in inflammation and infection.

Aims/Background

This study firstly aimed to identify and characterize a specific subset of DC CD209+/CD14+ and evaluate their characteristics at the periphery of inflammatory arthritic patients (IA). In addition, it aimed to evaluate the enrichment and activation of the specific DC subset at the site of inflammation, the join of IA patients.

Method

Peripheral blood and synovial fluid mononuclear cells (PBMC and SFMC) were isolated by Ficoll density gradient from healthy subject (HC), rheumatoid (RA) and psoriatic (PsA) arthritic patients. Single cell biopsy suspension from RA and PsA patients was obtained by enzymatic digestion. PBMC, SFMC and biopsy suspension were analysed by flow cytometry to identify the CD209+/CD14+ DC subset and its frequency (HLADR+/CD11c+). Chemokines receptors expression on the CD209+/CD14+ DC subset were also evaluated by flow cytometry.

Results

We identified the CD209+/CD14+ DC population in PBMC of RA and PsA patients and we observed that this population was enriched in SFMC of RA and PsA patients, with a further percentage increase in the synovial tissue cell suspension. In addition we identified a differential expression of chemokine receptors at the periphery of RA and PsA patients, when compared to the HC, with increased expression of CCR7 and decreased expression of CXCR3. This observation suggest that DCs are already activated and migratory in the periphery of IA patients. We further observed a unique profile of chemokines receptors in the synovial tissue cell suspension of RA and PsA patients, with an increased expression of CCR7 and CXCR3/5.

Conclusions

We identify for the first time in the periphery of RA and PsA patients the monocyte-derived DC population CD209+/CD14+ DC. This population was enriched at the site of inflammation and displayed a unique chemokine receptor profile, suggesting these cells are already activated in the periphery of IA patients, and are recruited and further activated into the joint of IA patients.