MicroRNA Expression in Cutaneous Lupus: A New Window to Understand Its Pathogenesis.

Background. The role of miRNAs in the pathogenesis of cutaneous lupus has not been studied. Objective. It was to assess the levels of a selected panel of circulating miRNAs that could be involved in the regulation of the immune response, inflammation, and fibrosis in cutaneous lupus. Methods. It was a cross-sectional study. We included 22 patients with subacute (SCLE) and 20 with discoid (DLE) lesions, and 19 healthy donors (HD). qRT-PCR for miRNA analysis, flow cytometry in peripheral blood, and skin immunohistochemistry were performed to determine the distribution of CD4 T cells and regulatory cells and their correlation with circulating miRNAs. Results. miR-150, miR-1246, miR-21, miR-23b, and miR-146 levels were downregulated in SCLE vs. HD. miR-150, miR-1246, and miR-21 levels were downregulated in DLE vs. HD. Peripheral CD4(+)/CD25(-)/IL-4(+) cells and CD4(+)/CD25(hi)/Foxp3(+) were negatively associated with miR-23b, and CD4(+)/CD25(-)/IFN-gamma(+) with miR-1246 in SCLE, whereas CD123(+)/CD196(+)/IDO+ cells were positively associated with miR-150 in DLE. In the tissue, CD4(+)/IL-4(+) and CD20(+)/IL-10(+) cells were positively associated with miR-21 and CD4(+)/IFN-gamma(+) with miR-31 in SCLE, whereas CD4(+)/IL-4(+) cells were positively associated with miR-150, and CD20(+)/IL-10(+) cells with miR-1246 and miR-146a in DLE. In the SCLE, lower miR-150 levels were correlated with higher CLASI scores. The KEGG pathway enrichment analysis revealed that cell cycle regulation pathways, p53, TGF-beta, thyroid hormone, and cancer signaling pathways were shared between miR-21, miR-31, miR-23b, miR-146a, miR-1246, and miR-150. Conclusions. A downregulation of miR-150, miR-1246, and miR-21 in both CLE varieties vs. HD was determined.