Background:Psoriasis is a frequent skin disease that can appear with an arthritic manifestation in approximately 30% of the cases [1]. The underlying excessive immune reaction caused by pro-inflammatory cytokines can be triggered by several risk factors [2]. Various subgroups of Dendritic cells (DCs) in the skin play a crucial role in the induction of the dermal inflammatory response [3].Objectives:As the role of peripheral blood DCs remains unknown and the cause of an arthritic manifestation is still not completely understood [4], this project aimed to detect differences in phenotype or function of peripheral blood DCs in psoriatic patients with or without arthritis.Methods:We analyzed peripheral blood cells of 60 psoriasis patients with and without arthritis. Different DC subpopulations were detected by flow cytometry. Monocyte-derived DCs were cultured with or without Lipopolysaccharides to gain immature (iDC) and mature (mDC) cells. The DC phenotype was determined by staining with CD80, CD83, CD86, CD206, CCR7, CD1a, HLA-DR, CD40, GPN-MB, DC209 and CD14. Their T-cell stimulatory capability was analyzed by co-incubation with Carboxyfluorescein succinimidyl ester stained lymphocytes and the quantification of CD4+ T-lymphocytes afterwards. To measure the migration capacity DCs were seated into transwell chambers with a semipermeable membrane and partly supplemented with Macrophage Inflammatory Protein 3 Beta (Mip3b). Migrated cells were detected by flow cytometry. Measured cell counts were normalized to cell counts without Mip3b stimulation.Results:Comparing the factor of increase of migrated mDC counts due to mip3b stimulation, we detected a significant lower rate in samples of patients with arthritis (PsA) compared to those of patients without (Ps). Assays of mDCs without mip3b stimulation showed a significant higher count of migrated cells in the samples of the arthritic group [Figure 1]. Cell counts with Mip3b stimulation did vary slightly in the groups. The DC subpopulations and the expression of analyzed cell surface proteins did not show significant differences. The amounts of stimulated T-Lymphocytes did not differ significantly.Figure 1.Migration essay showing mDCs following Mip3b (+miß3b) as multiples of mDCs without stimulation (-mip3b). The factor of increase is significantly lower in patients with arthritis (PsA) compared to patients without (Ps). Absolute counts of migrated mDCs without Mip3b are significantly higher in the arthritic group. Cell counts with stimulation do not differ significantly (data not shown). N=24, p<0.05Conclusion:CCL19 (Mip3b) is a potent ligand to the CCR7 receptor inducing migration of DCs towards the lymphatic node [5]. The CCR7 amounts on the DC surface did not differ significantly in the groups. The mDCs without CCL19 stimulation migrated in higher amounts in samples of arthritic patients. Cell counts of stimulated DCs showed only slight differences. These results could be generated by a different appearance of the DCs of arthritic patients that might facilitate migration. Further experiments focusing on this aspect should be performed. A possible effect of disruptive factors (age, sex, medication…) needs to be clarified.References:[1]Henes, J.C., et al.,High prevalence of psoriatic arthritis in dermatological patients with psoriasis: a cross-sectional study.Rheumatol Int, 2014.34(2): p. 227-34.[2]Lee, E.B., et al.,Psoriasis risk factors and triggers.Cutis, 2018.102(5s): p. 18-20.[3]Kim, T.G., S.H. Kim, and M.G. Lee,The Origin of Skin Dendritic Cell Network and Its Role in Psoriasis.Int J Mol Sci, 2017.19(1).[4]Veale, D.J. and U. Fearon,The pathogenesis of psoriatic arthritis.Lancet, 2018.391(10136): p. 2273-2284.[5]Ricart, B.G., et al.,Dendritic cells distinguish individual chemokine signals through CCR7 and CXCR4.J Immunol, 2011.186(1): p. 53-61.Acknowledgments:This project was financially supported by Novartis Pharma GmbH.Disclosure of Interests:Sarah Schnitte Grant/research support from: Reaserch grant by Novartis, Alexander Fuchs: None declared, Tanja Funk: None declared, Ann-Christin Pecher: None declared, Daniela Dörfel: None declared, Jörg Henes Grant/research support from: Novartis, Roche-Chugai, Consultant of: Novartis, Roche, Celgene, Pfizer, Abbvie, Sanofi, Boehringer-Ingelheim,
Identification of circulating regulatory T lymphocytes with membrane markers — a new multiparameter flow cytometry protocol
