MiR-200b modulates the properties of human monocyte-derived dendritic cells by targeting WASF3

The aim of the study was to explore the effect of miR-200b on the development of human peripheral blood monocyte-deriveddendritic-cell (DC) and its mechanisms.

Expression levels of miR-200b and its predicted targets were measured by real time-PCR. Protein expression of WASF3 was determined by Western blot and immunohistochemistry. Human peripheral blood mononuclear cells (PBMCs) were isolated by Ficoll-Hypaque density gradient centrifugation from the buffy coat fraction of anticoagulated blood. Monocytes were purified from PBMCs using anti-CD14 microbeads. The immunophenotypes of DCs were tested by flow cytometry.

A strong reduction in miR-200b expression was associated with human peripheral blood monocyte-derivedDC differentiation. The overexpression of miR-200b significantly reduced the numbers of protruding veils in mature DCs (mDCs) that are critical for promoting antigen-specificT-cell activation. Further experiments showed that miR-200b could regulate the function of DCs by targeting WASF3, a protein involved in cell movement and invasion.

Our results define an important function of miR-200b in the negative regulation of DC development and provide a potential form of miRNA-mediated cell therapy for diseases that range from auto-immunity to graft-versus-host disease.