Direct reprogramming of fibroblasts into antigen-presenting dendritic cells. Mus musculus

Ectopic expression of transcription factors has been used to reprogram differentiated somatic cells toward pluripotency or to directly reprogram them to other somatic cell lineages. This concept has been explored in the context of regenerative medicine. Here, we set out to generate dendritic cells (DCs) capable of presenting antigens from mouse and human fibroblasts. By screening combinations of 18 transcription factors that are expressed in DCs, we have identified PU.1, IRF8, and BATF3 transcription factors as being sufficient to reprogram both mouse and human fibroblasts to induced DCs (iDCs). iDCs acquire a conventional DC type 1–like transcriptional program, with features of interferon-induced maturation. iDCs secrete inflammatory cytokines and have the ability to engulf, process, and present antigens to T cells. Furthermore, we demonstrate that murine iDCs generated here were able to cross-present antigens to CD8+ T cells. Our reprogramming system should facilitate better understanding of DC specification programs and serve as a platform for the development of patient-specific DCs for immunotherapy. Overall design: Single cell mRNAseq profiling on single cells generated after transduction of mouse embryonic fibroblasts (MEFs) with Pu.1, Irf8, Baft3 at day 3, day 7 and day 9. mRNAseq profiling of MEFs and splenic dendritic cells CD11c+ MHC-II+ CD8a+ single cells were used as controls. Each sample represents a single cell. Bulk mRNAseq profiling on populations generated after transduction of mouse embryonic fibroblasts (MEFs) with lentivirus encoding Pu.1, Irf8, Baft3 at day 5, day 7, day 8 and day 9. mRNAseq profiling of MEFs and CD11c+ MHC-II+ CD8a+ cDC1s, CD11c+ MHC-II+ CD11b+ cDC2s and MHC-IIIntSiglecH+Bst2+ B220+ pDCs isolated from spleen were used as controls.