microRNA downregulation in plasmacytoid dendritic cells in interferon-positive systemic lupus erythematosus and antiphospholipid syndrome

Abstract Objective To investigate miRNA expression in relation to transcriptomic changes in plasmacytoid dendritic cells (pDCs) in SLE and APS. pDCs are major producers of IFNα in SLE and APS, and miRNAs are emerging as regulators of pDC activation. Methods miRNA and mRNA expression were measured by OpenArray and RNA-sequencing in pDCs of SLE, SLE + APS (APS secondary to SLE) and primary APS (PAPS) patients. The miRNA profile of patients was compared with the miRNA pattern of TLR7-activated pDCs. Results Among 131 miRNAs detected in pDCs, 35, 17 and 21 had a significantly lower level of expression in SLE, SLE + APS and PAPS patients, respectively, as compared with healthy controls (HC). Notably, the miRNA profile did not significantly differ between SLE and APS, but was driven by the presence or absence of an IFN signature. TLR7 stimulation induced a general downregulation of miRNAs, similar to the pattern observed in SLE and APS patients. miR-361-5p, miR-128-3p and miR-181a-2-3p expression was lower in patients with a high IFN signature (false discovery rate