miR-181d regulates human dendritic cell maturation through NF-κB pathway

MicroRNAs (miRNAs) are considered as the cellular regulators which post-transcriptionally modulate gene expression in diverse biological processes including cell development and immunity. In this study, we investigated functions of miR-181d in dendritic cells (DCs) maturation, and the underlying mechanisms were also explored.

Here we did the miRNA screening in human DCs in response to lipopolysaccharides (LPS) by quantitative real-time PCR (qRT-PCR). The expressions of DCs maturation markers were measured after miRNA mimics transfections. The pharmacological inhibitors of signalling pathways were applied to examine miR-181d effect on DCs maturation by Western blot. Luciferase assay and mixed lymphocyte reaction (MLR) were also performed to reveal the target gene of miR-181d and test the viability of T cells treated with miR-181d transfected DCs.

Overexpression of miR-181d per se is sufficient to promote DCs maturation, and up-regulate CD80 and CD83 expressions without LPS. Besides, we showed that miR-181d activated NF-κB pathway and also promoted the expression of pro-inflammatory cytokine IL12 and TNF-α. Inhibition of NF-κB pathway suppressed DCs maturation. Luciferase reporter assay and target gene knockdown assay indicated that miR-181d targets regulator cylindromatosis (CYLD), a primary negative regulator of NF-κB pathway. MLR assay showed that miR-181d-transfected DCs could promote T-cell proliferation than iDCs in vitro.

Our study demonstrates that miR-181d is required for DCs maturation through the activation of NF-κB pathway by targeting CYLD.