Abstract # 3100 Targeted modulation of neurotransmitter receptors on specific leukocyte subpopulations in rheumatoid arthritis

Background and Aim Current treatment strategies for rheumatoid arthritis (RA) including treat-to-target approaches are only partly successful. Therefore, new treatment options are still needed. There is some evidence for a role for dopamine (DA) in the pathogenesis of RA. Moreover, dopaminergic receptors (DR) are expressed on immune cells. The aim of this study was to further investigate the dopaminergic pathway in RA. Methods The expression of DRs (DRD1-5) was examined via flow cytometry in peripheral blood mononuclear cells (PBMC) of patients with RA (n = 5) and of healthy controls (HC, n = 5). In vitro experiments with DR-agonists were performed to determine the effects of DR-stimulation on immune cells. Results All investigated PBMC subpopulations expressed DRs, with the highest expression levels in NK cells and monocytes. Expression of DRD5 tended to be higher in RA NK cells, and DRD1 was upregulated in RA B-cells compared to HC. The activation marker CD69 was detected in all investigated PBMC subpopulations after 6 h and 22 h of stimulation with DR-agonists. Conclusion Our results show that DRs are present on immune cells and their expression seems to be modulated on defined subpopulations during RA. B cells, which are critical in RA, and NK cells appear attractive in context of dopaminergic treatment approaches. Further experiments are ongoing to better define the role of DA on peripheral immune cells during the course of the disease.