T‐cell exhaustion interrelates with immune cytolytic activity to shape the inflamed tumor microenvironment

BackgroundCD8+ T cells are a fundamental component of the anti-tumor response; however, tumor-infiltrating CD8+ T cells (TIL) are rendered dysfunctional by the tumor microenvironment. CD8+ TIL display an exhausted phenotype with decreased cytokine expression and increased expression of co-inhibitory receptors (IRs), such as PD-1 and Tim-3. The acquisition of IRs mark the progression of dysfunctional TIL from progenitors (PD-1Low) to terminally exhausted (PD-1+Tim-3+). How the chromatin landscape changes during this progression has not been described.MethodsUsing a low-input ChIP-based assay called Cleavage Under Targets and Release Using Nuclease (CUT&RUN), we have profiled the histone modifications at the chromatin of tumor-infiltrating CD8+ T cell subsets to better understand the relationship between the epigenome and the transcriptome as TIL progress towards terminal exhaustion.ResultsWe have identified two epigenetic characteristics unique to terminally exhausted cells. First, we have identified a unique set of genes, characterized by active histone modifications that do not have correlated gene expression. These regions are enriched for AP-1 transcription factor motifs, yet most AP-1 family factors are actively downregulated in terminally exhausted cells, suggesting signals that promote downregulation of AP-1 expression negatively impacts gene expression. We have shown that inducing expression of AP-1 factors with a 41BB agonist correlates with increased expression of these anticorrelated genes. We have also found a substantial increase in the number of genes that exhibit bivalent chromatin marks, defined by the presence of both active (H3K4me3) and repressive (H3K27me3) chromatin modifications that inhibit gene expression. These bivalent genes in terminally exhausted T cells are not associated with plasticity and represent aberrant hypermethylation in response to tumor hypoxia, which is necessary and sufficient to promote downregulation of bivalent genes.ConclusionsOur study defines for the first time the roles of costimulation and the tumor microenvironment in driving epigenetic features of terminally exhausted tumor-infiltrating T cells. These results suggest that terminally exhausted T cells have genes that are primed for expression, given the right signals and are the basis for future work that will elucidate that factors that drive progression towards terminal T cell exhaustion at the epigenetic level and identify novel therapeutic targets to restore effector function of tumor T cells and mediate tumor clearance.

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Cholesterol induces CD8+ T-cell exhaustion in the tumor microenvironment

European Journal of Cancer ◽

10.1016/j.ejca.2019.01.044 ◽

2019 ◽

Vol 110 ◽

pp. S9-S10

Author(s):

Q. Yi

Keyword(s):

T Cell ◽

Tumor Microenvironment ◽

Cd8 T Cell ◽

T Cell Exhaustion ◽

Cell Exhaustion

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Formation of the Immunosuppressive Microenvironment of Classic Hodgkin Lymphoma and Therapeutic Approaches to Counter It

International Journal of Molecular Sciences ◽

10.3390/ijms20102416 ◽

2019 ◽

Vol 20 (10) ◽

pp. 2416 ◽

Cited By ~ 10

Author(s):

Donatella Aldinucci ◽

Cinzia Borghese ◽

Naike Casagrande

Keyword(s):

T Cell ◽

Tumor Microenvironment ◽

Hodgkin Lymphoma ◽

Tumor Cells ◽

Current Knowledge ◽

Treatment Strategies ◽

T Cell Exhaustion ◽

Normal Cells ◽

Cell Exhaustion ◽

Classic Hodgkin Lymphoma

Classic Hodgkin lymphoma (cHL) is characterized by a few tumor cells surrounded by a protective, immunosuppressive tumor microenvironment composed of normal cells that are an active part of the disease. Hodgkin and Reed–Sternberg (HRS) cells evade the immune system through a variety of different mechanisms. They evade antitumor effector T cells and natural killer cells and promote T cell exhaustion. Using cytokines and extracellular vesicles, they recruit normal cells, induce their proliferation and “educate” (i.e. reprogram) them to become immunosuppressive and protumorigenic. Therefore, alternative treatment strategies are being developed to target not only tumor cells but also the tumor microenvironment. Here we summarize current knowledge on the ability of HRS cells to build their microenvironment and to educate normal cells to become immunosuppressive. We also describe therapeutic strategies to counteract formation of the tumor microenvironment and related processes leading to T cell exhaustion and repolarization of immunosuppressive tumor-associated macrophages.

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Neutrophil Extracellular Traps Promote T Cell Exhaustion in the Tumor Microenvironment

Frontiers in Immunology ◽

10.3389/fimmu.2021.785222 ◽

2021 ◽

Vol 12 ◽

Author(s):

Christof Kaltenmeier ◽

Hamza O. Yazdani ◽

Kristin Morder ◽

David A. Geller ◽

Richard L. Simmons ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Tumor Microenvironment ◽

Tumor Growth ◽

Cancer Metastasis ◽

Neutrophil Extracellular Traps ◽

T Cell Exhaustion ◽

Cell Exhaustion ◽

Extracellular Traps

While neutrophil extracellular traps (NETs) are important for directly promoting cancer growth, little is known about their impact on immune cells within the tumor microenvironment (TME). We hypothesize that NETs can directly interact with infiltrating T cells to promote an immunosuppressive TME. Herein, to induce a NET-rich TME, we performed liver Ischemia/Reperfusion (I/R) in an established cancer metastasis model or directly injected NETs in subcutaneous tumors. In this NET-rich TME, the majority of CD4+ and CD8+ tumor infiltrating lymphocytes expressed multiple inhibitory receptors, in addition these cells showed a functional and metabolic exhausted phenotype. Targeting of NETs in vivo by treating mice with DNAse lead to decreased tumor growth, decreased NET formation and higher levels of functioning T cells. In vitro, NETs contained the immunosuppressive ligand PD-L1 responsible for T cell exhaustion and dysfunction; an effect abrogated by using PD-L1 KO NETs or culturing NETs with PD-1 KO T cells. Furthermore, we found elevated levels of sPDL-1 and MPO-DNA, a NET marker, in the serum of patients undergoing surgery for colorectal liver metastases resection. Neutrophils isolated from patients after surgery were primed to form NETs and induced exhaustion and dysfunction of human CD4+ and CD8+ T cells. We next targeted PD-L1 in vivo by injecting a blocking antibody during liver I/R. A single dose of anti-PD-L1 during surgery lead to diminished tumors at 3 weeks and functional T cells in the TME. Our data thus reveal that NETs have the capability of suppressing T cell responses through metabolic and functional exhaustion and thereby promote tumor growth. Furthermore, targeting of PD-L1 containing NETs at time of surgery with DNAse or anti-PD-L1 lead to diminished tumor growth, which represents a novel and viable strategy for sustaining immune competence within the TME.

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Hemophagocytic lymphohistiocytosis in syntaxin-11–deficient mice: T-cell exhaustion limits fatal disease

Blood ◽

10.1182/blood-2012-07-441139 ◽

2013 ◽

Vol 121 (4) ◽

pp. 604-613 ◽

Cited By ~ 50

Author(s):

Tamara Kögl ◽

Jürgen Müller ◽

Birthe Jessen ◽

Annette Schmitt-Graeff ◽

Gritta Janka ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Nk Cells ◽

Hemophagocytic Lymphohistiocytosis ◽

Cytolytic Activity ◽

T Cell Exhaustion ◽

Inhibitory Receptors ◽

Cell Exhaustion ◽

Syntaxin 11 ◽

Deficient Mice

Abstract Syntaxin-11 (Stx11), an atypical member of the SNARE protein family, is part of the cytolytic machinery of T and NK cells and involved in the fusion of lytic granules with the plasmamembrane. Functional loss of syntaxin-11 in humans causes defective degranulation and impaired cytolytic activity of T and NK cells. Furthermore, patients with STX11 deficiency develop familial hemophagocytic lymphohistiocytosis type 4 (FHL4), a life-threatening disease of severe hyperinflammation. We established Stx11-deficient mice as an animal model for FHL4. Stx11-deficient mice exhibited severely reduced degranulation and cytolytic activity of CTL and NK cells and developed all clinical symptoms of hemophagocytic lymphohistiocytosis (HLH) after infection with lymphocytic choriomeningitis virus (LCMV). The HLH phenotype was further characterized by hyperactive CD8 T cells and continuous IFN-γ production. However, in contrast to perforin-deficient mice, which represent a model for FHL2, progression of HLH was not fatal. Survival of Stx11-deficient mice was determined by exhaustion of antigen-specific T cells, characterized by expression of inhibitory receptors, sequential loss of effector functions, and finally T-cell deletion. Blockade of inhibitory receptors on T cells in Stx11-deficient mice converted nonfatal disease course into fatal HLH, identifying T-cell exhaustion as an important factor for determination of disease severity in HLH.

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