Project description:During persistent antigen stimulation, PD-1+CD8 T cells are maintained by progenitor exhausted PD-1+TCF-1+CD8 T cells (Tpex). Tpex respond to PD-1 blockade, and regulation of Tpex differentiation into more functional Tex is of major interest for cancer immunotherapies. Tpex express high levels of Inducible Costimulator (ICOS), but the role of ICOS for PD-1+CD8 T cell responses has not been addressed. In chronic infection, ICOS-deficiency increased both number and quality of virus-specific CD8 T cells, with accumulation of effector-like Tex due to enhanced survival. Mechanistically, loss of ICOS signaling potentiated FoxO1 activity and memory features of Tpex. ICOS-deficient Tex displayed enhanced survival and improved cytokine production. In chronically-infected mice, ICOS-Ligand blockade expanded effector-like Tex, reduced viral load and potentiated anti-PD-L1 therapy. In a mouse model of hepatocellular carcinoma, ICOS inhibition improved cytokine production by tumor-specific PD-1+CD8 T cells and sensitized tumors to PD-1 targeted therapy. Overall, we show that sustained ICOS costimulation limits CD8 T cell responses during chronic antigen exposure.
Project description:During persistent antigen stimulation, PD-1+CD8 T cells are maintained by progenitor exhausted PD-1+TCF-1+CD8 T cells (Tpex). Tpex respond to PD-1 blockade, and regulation of Tpex differentiation into more functional Tex is of major interest for cancer immunotherapies. Tpex express high levels of Inducible Costimulator (ICOS), but the role of ICOS for PD-1+CD8 T cell responses has not been addressed. In chronic infection, ICOS-deficiency increased both number and quality of virus-specific CD8 T cells, with accumulation of effector-like Tex due to enhanced survival. Mechanistically, loss of ICOS signaling potentiated FoxO1 activity and memory features of Tpex. In mice with established chronic infection, ICOS-Ligand blockade resulted in expansion of effector-like Tex and reduction in viral load. In a mouse model of hepatocellular carcinoma, ICOS inhibition improved cytokine production by tumor-specific PD-1+CD8 T cells and delayed tumor growth. Overall, we show that ICOS constrains CD8 T cell responses during chronic antigen exposure.
Project description:During persistent antigen stimulation, PD-1+CD8 T cells are maintained by progenitor exhausted PD-1+TCF-1+CD8 T cells (Tpex). Tpex respond to PD-1 blockade, and regulation of Tpex differentiation into more functional Tex is of major interest for cancer immunotherapies. Tpex express high levels of Inducible T-cell Costimulator (ICOS), but the role of ICOS for PD-1+CD8 T cell responses has not been addressed. In chronic infection, ICOS-deficiency increased both number and quality of virus-specific CD8 T cells, with accumulation of effector-like Tex due to enhanced survival. Mechanistically, loss of ICOS signaling potentiated FoxO1 activity and memory features of Tpex. In mice with established chronic infection, ICOS-Ligand blockade resulted in expansion of effector-like Tex and reduction in viral load. In a mouse model of hepatocellular carcinoma, ICOS inhibition improved cytokine production by tumor-specific PD-1+CD8 T cells and delayed tumor growth. Overall, we show that ICOS constrains CD8 T cell responses during chronic antigen exposure.
Project description:Upon PD-1 pathway blockade,the epigenetic landscape of exhausted cells was only minimally remodeled consistent with lineage commitment and re-exhaustion of these cells over time.
Project description:T cell exhaustion is a state of CD8+ T cell dysfunction elicited by chronic exposure to antigen and inflammation, arises in both cancer and chronic viral infection. The co-inhibitory receptor PD-1 plays a key role in mediating exhaustion, but complete ablation of PD-1 by gene knock-out leads to deeper functional deficits and poor T cell survival. We hypothesized that an intermediate level of PD-1 expression may confer an improved balance of exhausted CD8+ T cell functionality, so we deleted an exhaustion-associated enhancer of PD-1 which indeed resulted in a reduced expression level. We compared EnhDel, WT and PD-1 KO T cells using single-cell RNA-Seq and found that PD-1 KO but not EnhDel cells are strongly biased towards the terminally exhausted subset. EnhDel cells also uniquely enrich for effector-associated genes and gene signatures. However, all three genotypes (EnhDel, WT and PD-1 KO) exhibit a similar chromatin accessibility landscape by ATAC-Seq, controlling for exhausted subset. These data suggest that tuning of PD-1 expression may uniquely permit the maintenance of an “effector” transcriptional profile in exhausted CD8+ T cells.
Project description:T cell exhaustion is a state of CD8+ T cell dysfunction elicited by chronic exposure to antigen and inflammation, arises in both cancer and chronic viral infection. The co-inhibitory receptor PD-1 plays a key role in mediating exhaustion, but complete ablation of PD-1 by gene knock-out leads to deeper functional deficits and poor T cell survival. We hypothesized that an intermediate level of PD-1 expression may confer an improved balance of exhausted CD8+ T cell functionality, so we deleted an exhaustion-associated enhancer of PD-1 which indeed resulted in a reduced expression level. We compared EnhDel, WT and PD-1 KO T cells using single-cell RNA-Seq and found that PD-1 KO but not EnhDel cells are strongly biased towards the terminally exhausted subset. EnhDel cells also uniquely enrich for effector-associated genes and gene signatures. However, all three genotypes (EnhDel, WT and PD-1 KO) exhibit a similar chromatin accessibility landscape by ATAC-Seq, controlling for exhausted subset. These data suggest that tuning of PD-1 expression may uniquely permit the maintenance of an “effector” transcriptional profile in exhausted CD8+ T cells.
Project description:T cell exhaustion is a state of CD8+ T cell dysfunction elicited by chronic exposure to antigen and inflammation, arises in both cancer and chronic viral infection. The co-inhibitory receptor PD-1 plays a key role in mediating exhaustion, but complete ablation of PD-1 by gene knock-out leads to deeper functional deficits and poor T cell survival. We hypothesized that an intermediate level of PD-1 expression may confer an improved balance of exhausted CD8+ T cell functionality, so we deleted an exhaustion-associated enhancer of PD-1 which indeed resulted in a reduced expression level. We compared EnhDel, WT and PD-1 KO T cells using single-cell RNA-Seq and found that PD-1 KO but not EnhDel cells are strongly biased towards the terminally exhausted subset. EnhDel cells also uniquely enrich for effector-associated genes and gene signatures. However, all three genotypes (EnhDel, WT and PD-1 KO) exhibit a similar chromatin accessibility landscape by ATAC-Seq, controlling for exhausted subset. These data suggest that tuning of PD-1 expression may uniquely permit the maintenance of an “effector” transcriptional profile in exhausted CD8+ T cells.