ABSTRACT
T cell immunity requires antigen capture by conventional dendritic cells (cDCs), digestion and transfer to draining lymph nodes for presentation to antigen-inexperienced T cells. cDCs type I excel as cancer-antigen presenting cells, due to their ability to phagocytose, slowly digest apoptotic cancer cells and translocate cancer antigens to the cytosol for loading to MHCI and cross-presentation to CD8 T cells 1–3. In tumor tissues cDCs1 become particularly scarce and this restricts anti-tumour immunity, immunotherapy responses and patient survival 4–8. Tumor cDC1 paucity is not fully understood and no specific treatment currently exists. Here, we find that type I interferons (IFN) induce lysosomal stress, lysosomal membrane permeabilization (LMP) and lysosomal-dependent cell death (LDCD) in cDCs1. Two parallel pathways downstream of IFNAR1 converged to induce cDC1 LDCD. Up-regulation of expression of lysosomal genes enhanced the proteolytic activity of lysosomes, while IFN-inducible guanylate binding protein-2 (GBP-2) accumulated in the membrane of the stressed lysosomes, leading to LMP, proteolytic enzyme release and death. Protease inhibition or GBP-2 repression rescued cDCs1 from LDCD and boosted their anti-tumor efficacy. GBPs are amongst the most abundant IFN-induced genes and known to form toxic pores in pathogen-containing vacuoles and pathogen membranes 9. GBP-2-driven LMP is likely due to the ability of GBP-2 to form pores on the lysosomes of cDC1s. This might have evolved as a physiological mechanism of antigen translocation to the cytosol for cross-presentation 10. We anticipate our findings to be a starting point for more rational cDC1-directed immunotherapies. For instance, protease inhibition, GBP-2 downregulation or induced expression of LMP repair machinery may boost cDC1 efficacy in adoptive cell therapies or their use as live vaccines11–13.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
In this version we have included new data.
