An NF-κB/IRF1 axis programs cDC1 to drive antitumor immunity

Conventional type 1 dendritic cells (cDC1s) are critical for anti-tumor immunity. They acquire antigens from dying tumor cells and cross-present them to CD8+ T cells, promoting the expansion of tumor-specific cytotoxic T cells. However, the signaling pathways that govern the anti -tumor functions of cDC1s are poorly understood. We mapped the molecular pathways regulating intratumoral cDC1 maturation using single cell RNA sequencing. We identified NF κB and IFN pathways as being highly enriched in a subset of functionally mature cDC1s. The specific targeting of NF-κB or IFN pathways in cDC1s prevented the recruitment and activation of CD8+ T cells and the control of tumor growth. We identified an NF-κB-dependent IFN-γ-regulated gene network in cDC1s, including cytokines and chemokines specialized in the recruitment and activation of cytotoxic T cells. We used single cell transcriptomes to map the trajectory of intra-tumoral cDC1 maturation which revealed the dynamic reprogramming of tumor-infiltrating cDC1s by NF-κB and IFN signaling pathways. This maturation process was perturbed by specific inactivation of either NF-κB or IRF1 in cDC1s, resulting in impaired expression of IFN-γ-responsive genes and consequently a failure to efficiently recruit and activate anti-tumoral CD8+ T cells. Finally, we demonstrate the relevance of these findings to cancer patients, showing that activation of the NF-κB/IRF1 axis in association with cDC1s is linked with improved clinical outcome. The NF-κB/IRF1 axis in cDC1s may therefore represent an important focal point for the development new diagnostic and therapeutic approaches to improve cancer immunotherapy. 14 samples were analysed, each sample is a tumor grown in an individual mouse, no replicates were included. Controls are Ikbkb_FF and Irf1_FF. Reference samples are Ikbkb_dXCR1 and Irf1_dXCR1.