Project description:Regulatory T cells (Tregs) have an immunosuppressive function and highly express PD-1 in tumor microenvironment, but the function of PD-1 in Tregs is still controversial. Using murine tumor model, we demonstrated that Tregs-specific PD-1 conditional Knock-Out mice are resistant to tumor progression. Using PD-1 hetero conditional Knock-Out mice in which both PD-1 expressing Tregs and deficient Tregs co-exist, we found that specific ablation of PD-1 on Tregs results in impaired proliferative capacity and functionality of Tumor-infiltrating Tregs. Single cell RNA and VDJ sequencing revealed that PD-1 signaling in TI Tregs induces global transcriptome crucial for Tregs homeostasis and functionality. Taken together, we suggest that specific ablation of PD-1 on Tregs promotes antitumor immunity by exacerbating Tregs stability and functionality.
Project description:Cellular senescence is a stress response known to activate innate immunity. However, how senescent cells interact with the adaptive immune system remains largely unexplored. Here, we show that senescent cells display an enhanced MHC class I antigen processing and presentation. Furthermore, senescent cells present an altered immunopeptidome including unique non-mutated antigens that can be recognized by specific CD8 T cells. Immunization of mice with senescent cancer cells triggers strong protective CD8-dependent antitumor responses, superior to immunogenic cell death. Similarly, induction of senescence in human primary cancer cells hyperactivates their cognate reactive CD8 T cell. Our study indicates that immunization with senescent cells provides a sustained source of antigens that strongly activate anti-tumor CD8 T cells.
Project description:MAVS-mediated cytosolic RNA sensing plays a central role in tumor immunogenicity. However, the effects of host MAVS signaling on antitumor immunity remains uncertain. Here, we demonstrate that host MAVS pathway drives accelerated tumor growth and impairs antitumor immunity, while MAVS knockout in dendritic cells (DCs) promotes tumor-reactive CD8+ T cell responses. Specifically, the CD8+ T cell priming capacity is enhanced by lack of functional MAVS in a type I interferon-independent, but IL-12-dependent, manner. Mechanistically, loss of RIG-I/MAVS cascade activates non-canonical NF-κB pathway and in turn induces IL-12 production by DCs, resulting in CD8+ T cell: DC crosstalk licensed by IFN-γ and IL-12. Moreover, ablation of host MAVS sensitizes tumors to immunotherapy and attenuates radiation resistance, thereby facilitating the maintenance of effector CD8+ T cells. These findings identify that host MAVS pathway acts as an immune checkpoint of DC-driven antitumor immunity, indicating the development of DC-based immunotherapies through MAVS signaling antagonism.
Project description:Depleting the NURF chromatin remodeling complex results in enhanced antitumor immunity using mouse tumor models syngenic to two strain backgrounds. Selective depletion of immune cells from tumor-bearing mice discovers that both CD8+ and CD4+ cells are necessary for enhanced antitumor immunity to NURF-depleted cells. Our results suggest that NURF-depleted cells have significant differences in antigenicity compared to control cells.
Project description:To investigate the role of aging in the regulation of CD8+ T cell anti-tumor function, we sorted CD8+T cells from Rag1-/- mice that were received intravenously injection of young/old mice-derived CD8+ T cells on the same day with tumor cell inoculation and carried out single-cell RNA sequencing, and the young group showed increased highly cytotoxic TRM and reduced exhausted CD8+ T cells in tumor microenvironment. Our study also found that BFAR deficiency reinvigorates tumor infiltrating CD8+ T cells into a more young state, as reflected by increased TRM.
Project description:Epigenetic mechanism contributes to immune landscapes in cancer. Here we identify the SETDB1-TRIM28 complex as a critical suppressor of antitumor immunity. An epigenetic CRISPR-Cas9 screen of 1,218 chromatin regulators identified TRIM28 as a novel suppressor of PD-L1 expression. We revealed that expression of the SETDB1-TRIM28 complex negatively correlates with infiltration of effector CD8+ T cells. Inhibition of SETDB1-TRIM28 simultaneously upregulates PD-L1 and activates the cGAS-STING innate immune response to increase infiltration of CD8+ T cells. Mechanistically, SETDB1-TRIM28 inhibition leads to micronuclei formation in cytoplasm, a known activator of the cGAS-STING pathway. Thus, SETDB1-TRIM28 inhibition bridges the innate and adaptive immunity. Indeed, SETDB1 knockout enhances the antitumor effects of immune checkpoint blockade anti-PD-L1 in an ovarian cancer mouse model in a cGAS dependent manner. Our findings establish SETDB1-TRIM28 complex as a regulator of antitumor immunity and its loss activates cGAS-STING innate immunity to boost antitumor effects of immune checkpoint blockades.
Project description:Epigenetic mechanism contributes to immune landscapes in cancer. Here we identify the SETDB1-TRIM28 complex as a critical suppressor of antitumor immunity. An epigenetic CRISPR-Cas9 screen of 1,218 chromatin regulators identified TRIM28 as a novel suppressor of PD-L1 expression. We revealed that expression of the SETDB1-TRIM28 complex negatively correlates with infiltration of effector CD8+ T cells. Inhibition of SETDB1-TRIM28 simultaneously upregulates PD-L1 and activates the cGAS-STING innate immune response to increase infiltration of CD8+ T cells. Mechanistically, SETDB1-TRIM28 inhibition leads to micronuclei formation in cytoplasm, a known activator of the cGAS-STING pathway. Thus, SETDB1-TRIM28 inhibition bridges the innate and adaptive immunity. Indeed, SETDB1 knockout enhances the antitumor effects of immune checkpoint blockade anti-PD-L1 in an ovarian cancer mouse model in a cGAS dependent manner. Our findings establish SETDB1-TRIM28 complex as a regulator of antitumor immunity and its loss activates cGAS-STING innate immunity to boost antitumor effects of immune checkpoint blockades.
Project description:Ionizing radiation promotes cytosolic DNA sensing and consequent antitumor immune responses. But how tumor cell-intrinsic cytosolic DNA sensing is initiated by radiation remains poorly defined. Here, we demonstrated that STING-mediated type I interferon production in tumor cells after radiation relied on the engagement of MLKL-mediated necroptosis, which was elicited by the ZBP1-RIPK3 signaling axis. Physiologically, tumor cell-intrinsic ZBP1-MLKL cascade augmented antitumor immune responses after radiation largely by regulating STING signaling. Mechanistically, ZBP1-MLKL-dependent necroptosis maintained the enrichment of mitochondria DNA inside the cytosol of tumor cells after radiation in a cell-density dependent fashion, contributing to type I interferon responses. In contrast, ablation of caspase-8 unleashed ZBP1-MLKL cascade to gain enhanced cytosolic DNA sensing, and in turn potentiated therapeutic effects of radiation. Thus, our findings uncover an unanticipated mechanism that ZBP1-MLKL-dependent necroptosis drives cytosolic DNA sensing-mediated antitumor immunity after radiation, and provide new strategy to improve radiotherapy by inhibiting caspase-8 cascade.