18A128

Tofacitinib Impairs Monocyte-Derived Dendritic Cell Differentiation In Rheumatoid Arthritis And Psoriatic Arthritis

Author(s)

Marzaioli Viviana, Canavan Mary, Floudas Achilleas, Wade Siobhán, Low Candice, Douglas J. Veale, Fearon Ursula

Department(s)/Institutions

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

Introduction

Tofacitinib (Pfizer) is an oral Janus kinase inhibitor, recently approved for the treatment of rheumatoid arthritis (RA) and psoriatic arthritis (PsA). Its effect on dendritic cells development and function remains still to be elucidated. Monocyte-derived dendritic cells (Mo-DC) are a subset of inflammatory DC derived from circulating monocytes and have a key role in inflammation and infection.

Aims/Background

To evaluate the effect of Tofacitinib on the ability of monocyte from RA and PsA patients to differentiate into dendritic cells, an important step in innate immunity.

Method

Monocytes were isolated from blood of healthy donor (HC), RA and PsA patients by magnetic separation and plated in presence/absence of GM-CSF/IL-4 cocktail for 7 days. Tofacitinib (1µM or DMSO as control) was added 15 minute prior to cytokine stimulation. CD209 and CD14 were evaluated by flow cytometry in the CD11c+ population. Dendritic cell uptake of soluble antigens by non-specific macropinocytosis (using Lucifer Yellow), and receptor-mediated endocytosis (using DQ Ovalbumin) were evaluated. Western blot analysis was utilized for analysis of NOX2, NOX5 and actin protein expression on the total cell lysate. Finally, the frequency of CD209 cells was evaluated by flow cytometry in both peripheral blood (PBMC) and synovial fluid (SFMC) mononuclear cells from RA and PsA patients.

Results

Mo-DC differentiation in RA and PsA patients was inhibited by Tofacitinib, as shown by reduced CD209 marker expression, paralleled by an increase of CD14 marker expression. The decreased differentiation ability was translated into a function impairment of phagocytic ability, as observed by the decreased uptake of both DQ Ovalbumin (receptor-mediated endocytosis) and Lucifer Yellow (macropinocytosis).
Tofacitinib decreased NOX5 and increased NOX2 protein expression in Mo-DC in both PsA and RA Mo-DC. Finally, we identified the CD209 population in PBMC cells from RA and PsA patients, and we observed an increased frequency of this population at the site of inflammation in SFMC cells from PsA and RA patients.

Conclusions

Together, these observations suggest a novel mechanism of action of Tofacitinib in RA and PsA, by inhibiting Mo-DC development, which may alter migration of DC to the joint and subsequent activation of the immune response.