Downregulation of Blimp1 inhibits the maturation of bone marrow-derived dendritic cells

Modulation of differentiation of dendritic cells (DCs), which are derived from bone marrow cells, may influence their maturation and consequently regulate their ability to present antigens to alloreactive T lymphocytes. B lymphocyte-induced maturation protein-1 (Blimp1) is a master regulator of immunocyte differentiation, which has been investigated for its effect on DCs. In the present study, a lentivirus was used as a vector to transduce Blimp1-short hairpin (sh)RNA into primary bone marrow cells during their differentiation to DCs. Lentiviral-mediated Blimp1-shRNA (lenti-shRNA-Blimp1) had a transduction efficiency of >60% in DC precursors. Lenti-shRNA-Blimp1 significantly downregulated the expression levels of Blimp1 and modulated the expression of its target proteins, including class II major histocompatibility complex (MHC) transactivator, c-myc and interleukin-6. Although lenti-shRNA-Blimp1 did not interfere with the differentiation of bone marrow cells to DCs, it inhibited DC maturation by decreasing the expression of surface MHC-II molecules, but not the expression of MHC-I molecules and co-stimulatory molecules [cluster of differentiation (CD)80/CD86]. Subsequently, alloreactive T cell proliferation was alleviated and regulatory T cells were expanded in response to lenti-shRNA-Blimp1. A toxicity assay indicated that the morphology and proliferation of cultured DCs were mildly influenced by the lentiviral vector, indicating that the use of alternative vectors with minimal or no toxicity could be investigated in future studies. In conclusion, transduction with lenti-shRNA-Blimp1 modulated the maturation of DCs via MHC-II molecule suppression and inhibited alloreactive T cell activation. The present findings supported the application of Blimp1-based intervention as a novel approach to induce immature DCs for further immunological research.