Dendritic cells' characteristics in patients with treated systemic lupus erythematosus

The systemic lupus erythematosus (SLE) is a chronic autoimmune disease related to a loss of immune tolerance against autoantigens that leads to tissue inflammation and organ dysfunction. Constant stimulation of dendritic cells (DC) with autoantigens is hypothesized to increase the B cells' activity which are involved in production of autoantibodies that play an essential role in the SLE development. We focused our study on detecting alterations in DCs at the cellular and molecular levels in patients with treated SLE, depending on the disease activity and treatment. In order to phenotype subpopulations of DCs, multicolor flow cytometry was used. Transcriptional changes were identified with quantitative PCR, while soluble cytokine receptors were assessed with the Luminex technology. We show that SLE patients display a higher percentage of activated myeloid DCs (mDCs) when compared to healthy people. Both, the mDCs and plasmacytoid DCs (pDCs) of SLE patients were characterized by changes in expression of genes associated with their maturation, functioning and signalling, which was especially reflected by low expression of regulatory factor ID2 and increased expression of IRF5. pDCs of SLE patients also showed increased expression of IRF1. There were also significant changes in the expression of APRIL, MBD2, and E2-2 in mDCs that significantly correlated with some serum components, i.e. anti-dsDNA antibodies or complement components. However, we did not find any significant differences depending on the disease activity. While the majority of available studies focuses mainly on the role of pDCs in the disease development, our results show significant disturbances in the functioning of mDCs in SLE patients, thus confirming mDCs' importance in SLE pathogenesis.