Project description:TGFb signaling is a major pathway associated with poor clinical outcome in patients with
advanced metastatic cancers and non-response to immune checkpoint blockade, particularly in the immune-excluded tumor phenotype. While previous pre-clinical studies demonstrated that converting tumors from an excluded to an inflamed phenotype and curative anti-tumor immunity require attenuation of both PD-L1 and TGFb signaling, the underlying cellular mechanisms remain unclear. Recent studies suggest that stem cell-like CD8 T cells (TSCL) can differentiate into non-exhausted CD8 T effector cells that drive durable anti-tumor immunity. Here, we show that TGFb and PD-L1 restrain TSCL expansion as well as replacement of progenitor exhausted and dysfunctional CD8 T cells with non-exhausted IFNghi CD8 T effector cells in the tumor microenvironment (TME). Blockade of TGFb and PD-L1 generated IFNghi CD8 T effector cells with enhanced motility, enabling both their accumulation in the TME and increased interaction with other cell types. Ensuing IFNg signaling markedly transformed myeloid, stromal, and tumor niches to yield a broadly immune-supportive ecosystem. Blocking IFNg completely abolished the effect of anti-PD-L1/ TGFb combination therapy. Our data suggest that TGFb works in concert with PD-L1 to prevent TSCL expansion and replacement of exhausted CD8 T cells with fresh CD8
T effector cells, thereby maintaining the CD8 T cell compartment in a dysfunctional state.
Project description:In this study we have examined how the cytokine interleukin-2 (IL-2) synergizes with programmed cell death-1 (PD-1) directed immunotherapy during chronic lymphocytic choriomeningitis virus (LCMV) infection. PD-1 blockade in combination with IL-2 is one of the most effective combination therapies in this very stringent LCMV mouse model of life-long chronic infection with irreversible T-cell exhaustion. Our paper makes the following points: First, we show that the more effective viral control seen after PD-1/IL-2 combination therapy compared to PD-1 monotherapy is mediated by the CD8+T-cell response. Then we identify the virus-specific CD8+T cells that proliferate and respond to the combination therapy and show that these are the same lymphoid resident PD-1+TCF-1+stem-like CD8+T cells that act as resource cells to maintain the CD8+T-cell response during chronic infection and also respond to PD-1 blockade. However, the combination therapy dramatically changes the differentiation program of these chronic resource CD8+T cells and results in the generation of transcriptionally and epigenetically distinct effector CD8+T cells that resemble highly functional effector CD8+T cells seen after an acute viral infection. In contrast, PD-1 monotherapy doesnot modify the differentiation program and one gets more virus-specific CD8+T cells but they are transcriptionally and epigenetically similar to what is seen in untreated chronically infected mice. This epigenetic inflexibility of exhausted CD8+T cells is a potential barrier to PD-1 therapy and the ability of this combination therapy to modify the epigenetic signature of virus-specific CD8+T cells during chronic infection could be an important determinant of the striking synergy seen between IL-2 therapy and PD-1 blockade. We also highlight the importance of blocking the PD-1/PD-L1 inhibitory pathway at the target site for effective viral control. Expanding the CD8+ Tcell population and generating better effector cells is important but it is also critical to block PD-1 inhibitory signals at the target site for optimal immunotherapy. Finally, we show that CD25 engagement with IL-2 plays an important and essential role in the observed synergy between IL-2 cytokine and PD-1 blockade. Either blocking CD25 with an antibody or using a mutated version of IL-2 that does not bind CD25 but still binds CD122/132 almost completely abrogated the synergistic effects seen after PD-1/IL-2 combination therapy. There is currently considerable interest in PD-1/IL-2 combination therapy for cancer patients and our fundamental studies defining the underlying mechanisms of how IL-2 synergizes with PD-1 blockade should inform these human translational studies.
Project description:Blockade of programmed death-1 (PD-1) reinvigorates exhausted CD8+ T cells, resulting in tumor regression in cancer patients. Recently, reinvigoration of exhausted CD8+ T cells following PD-1 blockade was shown to be CD28-dependent in mouse models. Herein, we examined the role of CD28 in anti-PD-1-induced human T-cell reinvigoration using tumor-infiltrating CD8+ T cells (CD8+ TILs) obtained from non-small cell lung cancer patients. Single cell analysis demonstrated a distinct expression pattern of CD28 between mouse and human CD8+ TILs. Furthermore, we found that human CD28+CD8+, but not CD28–CD8+ TILs, responded to PD-1 blockade irrespective of B7/CD28 blockade, indicating that CD28 co-stimulation in human CD8+ TILs is dispensable for PD-1 blockade-induced reinvigoration, and loss of CD28 expression rather serve as a marker of anti-PD-1-unresponsive CD8+ TILs. Transcriptionally and phenotypically, PD-1 blockade-unresponsive human CD28–PD-1+CD8+ TILs exhibited characteristics of terminally exhausted CD8+ T cells with low TCF1 expression. Notably, CD28–PD-1+CD8+ TILs had preserved machinery to respond to IL-15, and IL-15 treatment enhanced proliferation of CD28–PD-1+CD8+ TILs as well as CD28+PD-1+CD8+ TILs. Taken together, we demonstrate loss of CD28 expression as a marker of PD-1 blockade-unresponsive human CD8+ TILs with TCF1– signature and provide mechanistic insights into combining IL-15 with anti-PD-1.
Project description:Vaccination induces immunostimulatory signals which are often accompanied by regulatory mechanisms such as IL-10, which control T-cell activation and inhibit vaccine-dependent antitumor therapeutic effect. Thus, here we characterized IL-10-producing cells treated with therapeutic vaccines. Although several cell subsets produced IL-10 irrespective of treatment, an early vaccine-dependent induction of IL-10 was detected in dendritic cells (DC). IL-10 production defined a DC population characterized by a poorly mature phenotype, lower expression of T-cell stimulating molecules and upregulation of PD-L1. These IL-10+ DC showed impaired in vitro T-cell stimulatory capacity, which was rescued by incubation with IL-10R and PD-L1-inhibiting antibodies. In vivo IL-10 blockade during vaccination decreased the proportion of IL-10+ DC and improved their maturation, without modifying PD-L1 expression. Similarly, PD-L1 blockade did not affect IL-10 expression, suggesting independent regulation of these molecules. Interestingly, vaccination combined with simultaneous blockade of IL-10 and PD-L1 induced stronger immune responses, resulting in a higher therapeutic efficacy in tumor-bearing mice. These results show that vaccine-induced immunoregulatory DC with dual expression of IL-10 and PD-L1 impair priming of antitumor immunity, suggesting that therapeutic vaccination protocols may benefit from combined targeting of these molecules.
Project description:CD4+ T cell help is critical for optimal CD8+ T cell expansion after priming in many experimental systems. However, a role for CD4+ T cells in regulating the initial steps of CD8+ T cell effector differentiation is not well established. Here we demonstrate that absence of CD4+ T cells at the time of replication-incompetent adenovirus vector immunization of C57BL/6 mice led to immediate CD8+ T cell dysfunction characteristic of exhaustion at the first detectable timepoints as well as impaired expansion of antigen-specific CD8+ T cells. The absence of CD4+ T cell help resulted in antigen-specific CD8+ T cells that had reduced ex vivo cytotoxicity and decreased capacity to produce IFN-γ and TNF-α. CD8+ T cells primed in the absence of CD4+ T cells expressed elevated levels of the inhibitory receptors PD-1, LAG-3, and Tim-3, and these cells exhibited transcriptomic exhaustion profiles by gene set enrichment analysis. This dysfunctional state was imprinted within 3 days of immunization and could not be reversed by provision of CD4+ T cell help after priming. Partial rescue of unhelped CD8+ T cell expansion and effector differentiation could be achieved by PD-1 pathway blockade or recombinant IL-2 administration. This study identifies a novel, previously undescribed role of CD4+ T cells to prevent immediate dysfunction and features of exhaustion in CD8+ T cells following antigen priming. Splenic AL11-specific CD8 T cells from mice immunized with Ad5HVR48(1-7)-SIV Gag and treated with anti-CD4 antibody or not were purified by FACS on day 14 post-immunization
Project description:During acute viral infections, naïve CD8+ T cells differentiate into effector CD8+ T cells and, after viral control, into memory CD8+ T cells. Memory CD8+ T cells are highly functional, proliferate rapidly upon reinfection and persist long-term without antigen. In contrast, during chronic infections, CD8+ T cells become “exhausted” and have poor effector function, express multiple inhibitory receptors, possess low proliferative capacity, and cannot persist without antigen. Exhuasted CD8+ T cells can be further segregated by their expression of the inhibitory cell surface receptor PD-1. We performed transcriptional profiling on both PD-1 High and PD-1 Intermediate H2-Db GP33-specific CD8+ T cells. H2-Db GP33-specific CD8+ T cells were sorted from C57BL/6 mice 30 days p.i. with LCMV clone 13. These cells were then segregated by their expression of the inhibitory cell surface receptor PD-1 into PD-1 High and PD-1 Intermediate subpopulations. We performed transcriptional profiling on these subpopulations.
Project description:Development of a vaccine formula that alters the tumour-infiltrating lymphocytes to be more immune active against a tumour is key to the improvement of clinical responses to immunotherapy. Here, we demonstrate that, in conjunction with E7 antigen specific immunotherapy, and IL-10 and PD-1 blockade, intra-tumoral administration of caerin 1.1 and 1.9 peptides further improves the tumour microenvironment (TME) when compared with injection of a control peptide. We used single cell transcriptomics and mass spectrometry-based proteomics to quantify changes in cellular activity across different cell types within the TME. We show that the injection of caerin 1.1/1.9 increases immune activating macrophages and NK cells, while reducing immunosuppressive macrophages with M2 phenotype, and increased numbers of activated CD8+ T cells with higher populations of memory and effector-memory CD8+ T subsets. Proteomic profiling demonstrated activation of Stat1 modulated apoptosis and production of nitric oxide. Further, computational integration of the proteome with the single cell transcriptome was consistent with deactivation of immune suppressive B cell function following caerin 1.1 and 1.9 treatment.
Project description:While T cell accumulation in tumors is associated with response to immune checkpoint blockade (ICB), many T cell-rich tumors fail to respond to ICB. Here we leveraged a large neoadjuvant PD-1 blockade trial in hepatocellular carcinoma (HCC) to search for correlates of ICB response within T cell-rich tumors. Paired scRNAseq/TCRseq of nearly one million immune cells revealed that tumor responses to ICB correlated with significant clonal expansion of intratumoral CH25H+CXCL13+IL-21+CD4 T cells and GranzymeK+PD-1+CD8 effector T cells, whereas terminally exhausted CD39hiToxhiPD-1hi CD8 clones dominated in non-responders. Notably, proliferating and progenitor CD8 T cells clones were found in tumors of responders and non-responders. However, tumors from responders were highly enriched in mregDCs, a DC state triggered by capture of tumor debris, which formed physically interacting cellular triads with Tfh-like CD4 and progenitor-like CD8 T cells. Receptor-ligand analysis revealed unique interactions within these triads that may promote progenitor CD8 T cell differentiation into effector cells upon PD-1 blockade. These results suggest that discrete cellular niches that include mregDCs and Tfh-like CD4 T cells might control the differentiation of tumor-specific progenitor CD8 T cell clones into effective anti-tumor T cells in human tumors.