Gasdermin D deficiency promotes antitumor immunity by upregulating Type I ISG program in Antigen-presenting cells in response to PD-L1 antibody treatment

The tumor immune microenvironment is complex in composition, function and dynamic, influencing the evolution of tumor, prognosis and response to immunotherapy. Recent studies have significantly advanced our knowledge of the roles of Gasdermin protein-mediated tumoral pyroptosis activated by caspases and granzymes from cytotoxic lymphocytes in facilitating the killing of tumor cells. However, the pyroptosis of immune cells in tumor microenvironment and their affecting the reprogram of the tumor microenvironment remains poorly understood. In this study, we find that Gasdermin D (GSDMD), among Gasdermin family proteins, is significantly positively correlated with the immune checkpoint signature, and inversely linked to the overall survival of cancer patients by the analysis with TCGA clinical data. Using conditional knockout of GSDMD together with immunofluorescence co-labeling and single-cell RNA sequencing (scRNA-seq), we demonstrate that GSDMD mainly on antigen-presenting cells (APCs) such as macrophages and dendritic cells (DCs) in tumor microenvironment, restrains anti-tumor immunity under the treatment of PD-L1 antibody. Loss of GSDMD in APCs enhanced Type I interferon-stimulated gene (ISG) program of such cells, which promotes antigen presentation of macrophages and DCs, and facilitates the production of CD8+ effector and functional T cell. We further demonstrate that GSDMD deficiency increases anti-tumor immunity in a cyclic GMP–AMP synthase (cGAS)-dependent manner. Moreover, pharmacological inhibition of GSDMD-mediated pyroptosis significantly improves anti-tumor immunity in combination with PD-L1 antibody immunotherapy. Together, our findings reveal an important role for GSDMD-mediated pyroptosis of APCs such as macrophages and DCs in regulating CD8+ T cell function and underscore the potential of GSDMD blockade in promoting anti-tumor immunity, which may help the development of cancer immunotherapy. Overall design: To investigate the specific role of Gsdmd of DCs and macrophages in tumor immunity, we implanted subcutaneously B16F10 tumor cell into Gsdmdfl/fl Cx3cr1-cre and Cx3cr1-cre mice, anti-PD-L1 were intraperitoneally injected on day 4, 8. Tumors were collected on day 14 for single-cell RNA-seq. Single-cell RNA-seq data of tumor infiltrates immune cells were generated from twice independent experiments, in which experiment, cells were mixed from three Cx3cr1-cre and Gsdmdfl/fl Cx3cr1-cre mice.