Serum-derived exosomes promote CD8+ T cells to overexpress PD-1, affecting the prognosis of hypopharyngeal carcinoma

Abstract Background Hypopharyngeal cancer (HPC) is associated with a poor prognosis and a high recurrence rate. Immune escape is one of the reasons for the poor prognosis of malignant tumors. Programmed cell death ligand 1 (PD-L1) and programmed cell death-1 (PD-1) have been shown to play important roles in immune escape. However, the role of PD-1/PD-L1 in HPC remains unclear. In this experiment, we investigated the effect of exosomes from HPC patient serum on CD8+ T cell function and PD-1/PD-L1 expression and, thus, on prognosis. We hope to provide guidance for the identification of new targets for HPC immunotherapy. Methods PD-1 and CD8 expression in 71 HPC tissues and 16 paracarcinoma tissues was detected by immunohistochemistry. Concurrently, the clinicopathological data of the patients were obtained to conduct correlation analysis. Exosomes were isolated from serum and then identified by Western blotting (WB), transmission electron microscopy (TEM), and nanoparticle tracking analysis (NTA). Flow cytometry was used to assess the activity of CD8+ T cells after exosome stimulation. The effects of exosomes on the ability of CD8+ T cells to kill FaDu cells were assessed by CCK-8 assay. The expression of IL-10 and TGF-β1 was measured by enzyme-linked immunosorbent assay (ELISA). PD-L1 expression in HPC tissue samples was evaluated by immunohistochemistry, and the relationship between PD-1/PD-L1 expression and prognosis was investigated with patient specimens. Results PD-1 expression was significantly upregulated on CD8+ T cells in tumor tissues compared with those in normal tissues. The overall survival (OS) and disease-free survival (DFS) of PD-1-overexpressing patients were decreased. Serum exosomes from patients can elevate PD-1 expression on CD8+ T cells and suppress their killing capacity and secretory function. The rate of positive PD-L1 expression was increased in HPC tissues compared with paracancerous tissues. The DFS and OS of the PD-1(+)-PD-L1(+) group were significantly lower than those of the PD-1(−)-PD-L1(−) group. Conclusion Our findings indicate that serum exosomes from HPC patients can inhibit CD8+ T cell function and that the PD-1-PD-L1 pathway plays an important role in the immune escape of HPC. Exosomes combined with immunotherapy may guide the treatment of patients with advanced disease in the future.

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Limited Predictive or Prognostic Role of Tumor-Infiltrating Tissue-Resident Memory CD8 T Cells in Patients with Hepatocellular Carcinoma Receiving Immunotherapy

Cancers ◽

10.3390/cancers13205142 ◽

2021 ◽

Vol 13 (20) ◽

pp. 5142

Author(s):

Ying-Chun Shen ◽

Ching-Ping Yeh ◽

Yung-Ming Jeng ◽

Chiun Hsu ◽

Chih-Hung Hsu ◽

...

Keyword(s):

Hepatocellular Carcinoma ◽

T Cells ◽

Cell Death ◽

T Cell ◽

Programmed Cell Death ◽

Cd8 T Cells ◽

Tumor Response ◽

Cd8 T Cell ◽

Immunohistochemical Method ◽

Memory Cd8 T Cells

Purpose: Tumor-infiltrating tissue-resident memory CD8 T cells (CD8 TRM; CD103+ CD8+) are considered tumor-specific and may correlate better with the tumor response to immune checkpoint blockade (ICB). This study evaluated the association of tumor-infiltrating CD8 TRM and their subsets with the efficacy of immunotherapy in patients with advanced hepatocellular carcinoma (HCC). Experimental Design: Consecutive HCC patients who received ICB in prospective trials were analyzed. Formalin-fixed paraffin-embedded tumor sections were stained for DAPI, CD8, CD103, CD39, programmed cell death-1 (PD-1), and programmed cell death ligand 1 (PD-L1) using a multiplex immunohistochemical method. The densities of CD8 T cells, CD8 TRM, and CD39+ or PD-L1+ subsets of CD8 TRM were correlated with tumor response and overall survival (OS). Results: A total of 73 patients were identified, and 48 patients with adequate pretreatment tumor specimens and complete follow-up were analyzed. A median of 32.7% (range: 0–92.6%) of tumor-infiltrating CD8 T cells were TRM. In subset analyses, 66.6% ± 34.2%, 69.8% ± 33.4%, and 0% of CD8 TRM cells coexpressed CD39, PD-L1, and PD-1, respectively. The objective response rates for CD8 T cell-high, CD8 TRM-high, CD39+ CD8 TRM-high, and PD-L1+ CD8 TRM-high groups were 41.7%, 37.5%, 37.5%, and 29.2%, respectively. Patients with CD8 T cell-high, but not those with CD8 TRM-high, CD39+ CD8 TRM-high, or PD-L1+ CD8 TRM-high, tumors, had significantly prolonged OS (p = 0.0429). Conclusions: Compared with total tumor-infiltrating CD8 T cells, tumor-infiltrating CD8 TRM or their subsets failed to provide additional advantages in predicting the efficacy of immunotherapy for HCC.

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Immunodominant Cytomegalovirus Epitopes Suppress Subdominant Epitopes in the Generation of High-Avidity CD8 T Cells

Pathogens ◽

10.3390/pathogens10080956 ◽

2021 ◽

Vol 10 (8) ◽

pp. 956

Author(s):

Kirsten Freitag ◽

Sara Hamdan ◽

Matthias J. Reddehase ◽

Rafaela Holtappels

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Immune Escape ◽

Cd8 T Cell ◽

Antigenic Drift ◽

Murine Cytomegalovirus ◽

High Avidity ◽

Infected Cells ◽

Cd8 T Cell Memory

CD8+ T-cell responses to pathogens are directed against infected cells that present pathogen-encoded peptides on MHC class-I molecules. Although natural responses are polyclonal, the spectrum of peptides that qualify for epitopes is remarkably small even for pathogens with high coding capacity. Among those few that are successful at all, a hierarchy exists in the magnitude of the response that they elicit in terms of numbers of CD8+ T cells generated. This led to a classification into immunodominant and non-immunodominant or subordinate epitopes, IDEs and non-IDEs, respectively. IDEs are favored in the design of vaccines and are chosen for CD8+ T-cell immunotherapy. Using murine cytomegalovirus as a model, we provide evidence to conclude that epitope hierarchy reflects competition on the level of antigen recognition. Notably, high-avidity cells specific for non-IDEs were found to expand only when IDEs were deleted. This may be a host’s back-up strategy to avoid viral immune escape through antigenic drift caused by IDE mutations. Importantly, our results are relevant for the design of vaccines based on cytomegaloviruses as vectors to generate high-avidity CD8+ T-cell memory specific for unrelated pathogens or tumors. We propose the deletion of vector-encoded IDEs to avoid the suppression of epitopes of the vaccine target.

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596 Combining Bempegaldesleukin (CD122-preferential IL-2 pathway agonist) and NKTR-262 (TLR7/8 agonist) pairs local innate activation with systemic CD8+ T cell expansion to enhance anti-tumor immunity

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2021-sitc2021.596 ◽

2021 ◽

Vol 9 (Suppl 3) ◽

pp. A626-A626

Author(s):

Annah Rolig ◽

Daniel Rose ◽

Grace Helen McGee ◽

Saul Kivimae ◽

Werner Rubas ◽

...

Keyword(s):

T Cells ◽

Cell Death ◽

T Cell ◽

Immune Responses ◽

Cd8 T Cells ◽

Cd8 T Cell ◽

T Cell Response ◽

Cycle Phase ◽

Tumor Cell Death ◽

Specific Immunity

BackgroundTumor cell death caused by radiation therapy (RT) can trigger anti-tumor immune responses in part because dying cells release adjuvant factors that amplify and sustain DC and T cell responses. We previously demonstrated that bempegaldesleukin (BEMPEG:NKTR-214, a first-in-class CD122-preferential IL-2 pathway agonist), significantly enhanced the anti-tumor efficacy of RT through a T cell-dependent mechanism. Because RT can induce either immunogenic or tolerogenic cell death, depending on a multitude of factors (radiation dose, cell cycle phase, and tumor microenvironment), we hypothesized that providing a specific immunogenic adjuvant, like intratumoral NKTR-262, a novel toll-like receptor (TLR) 7/8 agonist, to the tumor site would further improve systemic tumor-specific immunity by promoting synergistic activation of local immunostimulatory innate immune responses. Therefore, we evaluated whether intratumoral NKTR-262, combined with systemic BEMPEG treatment would result in improved tumor-specific immunity and survival compared to BEMPEG combined with RT.MethodsTumor-bearing mice (CT26; EMT6) received BEMPEG (0.8 mg/kg; iv), RT (16 Gy x 1), and/or intratumoral NKTR-262 (0.5 mg/kg). Flow cytometry was used to evaluate CD4+ and CD8+ T cell activation status in the blood and tumor (7 days post-treatment). The contribution of specific immune subsets was determined by depletion of CD4+, CD8+, or NK cells. CD8+ T cell cytolytic activity was determined in vitro with an Incucyte assay. Data are representative of 1–2 independent experiments (n=5–14/group) and statistical significance was determined by 1-way ANOVA (p-value cut-off of 0.05).ResultsBEMPEG/NKTR-262 resulted in significantly improved survival compared to BEMPEG/RT. Both combination therapies were CD8+ T cell dependent. However, response to BEMPEG/NKTR-262 was characterized by a significant expansion of activated CD8+ T cells (GzmA+; Ki-67+; ICOS+; PD-1+) in the blood, which correlated with reduced tumor size (p<0.05). In the tumor, BEMPEG/NKTR-262 induced higher frequencies of GzmA+ CD8+ T cells exhibiting reduced expression of suppressive molecules (PD-1+, TIM-3+), compared to BEMPEG/RT. Additionally, CD8+ T cells isolated from BEMPEG/NKTR-262-treated tumors had greater cytolytic capacity than those from BEMPEG/RT-treated mice.ConclusionsCombining BEMPEG with NKTR-262 lead to a more robust expansion of activated CD8+ T cells compared to the BEMPEG/RT combination. Enhancement of the activated CD8+ T cell response in mice treated with NKTR-262 in combination with BEMPEG suggests that intratumoral TLR stimulation provides superior antigen presentation and costimulatory activity compared to RT. A clinical trial of BEMPEG/NKTR-262 for patients with metastatic solid tumors is in progress (NCT03435640).

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677 Reverse abscopal effect: intertumoral heterogeneity suppresses systemic CD8 T cell-mediated antitumor immunity and confers PD-1 inhibitor resistance in synchronous melanoma

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2021-sitc2021.677 ◽

2021 ◽

Vol 9 (Suppl 3) ◽

pp. A705-A705

Author(s):

Shuyang Qin ◽

Booyeon Han ◽

Alexander Chacon ◽

Alexa Melucci ◽

Alyssa Williams ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cell Line ◽

Cd8 T Cells ◽

Antitumor Immunity ◽

Immune Escape ◽

Cd8 T Cell ◽

Abscopal Effect ◽

Immunogenic Tumor ◽

Ifn Γ

BackgroundDespite recent advancements in systemic therapy, only a minority of metastatic patients develop meaningful clinical responses to immune checkpoint inhibitors. Inherent genetic instability of melanoma generates genomically and microenvironmentally distinct metastases. These different tumor microenvironments (TMEs) contain numerous T cell suppression mechanisms, such as upregulation of the PD-1/PD-L1 exhaustion pathway. However, as synchronous metastases share one host immune system, intertumoral heterogeneity may result in increasing cross-talk between metastases that impairs systemic antitumor immunity and promotes PD-1 immunotherapy resistance.MethodsYUMM 1.7 (less immunogenic) and YUMMER 1.7 (more immunogenic cell line derived from YUMM following UVB irradiation) melanoma cell lines were simultaneously injected into opposite flanks of the same mice as a model of synchronous melanoma. We assessed tumor growth in wildtype, interferon-gamma (IFN-γ) knockout, and CD8-depleted mice as well as in response to PD-1 inhibitor. We characterized the TME with flow cytometry and performed TCR sequencing on tumor-infiltrating CD8 T cells.ResultsDistinct TMEs were observed for YUMM and YUMMER tumors simultaneously grown in the same mouse. The presence of the less immunogenic YUMM tumor allows the more immunogenic YUMMER tumors to escape IFN-γ and CD8 T cell-mediated rejection, despite abundant tumor-infiltrating, clonally expanded CD8 T cells. Identical immunodominant CD8 T cell clones were found in both YUMM and YUMMER tumors within the same mouse. Synchronous YUMMER-infiltrating CD8 T cells exhibit suppressed phenotypes, including increased persistence of surface PD-1 and decreased surface CD107a expressions. Simultaneously, these synchronous YUMMER tumors additionally upregulate macrophage surface PD-L1 expression, which potentially contributes to tumor immune escape. Lastly, synchronous YUMMER tumors become resistant to PD-1 inhibition, in direct contrast to control YUMMER tumors.ConclusionsIn a host with multiple melanoma lesions, immunogenicity of all tumors contribute to the systemic antitumor immune response. We show that two synchronous tumors with synonymous mutations (<40%), as is the case with metastatic patients, lead to skewed CD8 T cell expansion of the same clones in both tumors. The presence of a less immunogenic tumor prevents CD8 and IFN-γ mediated rejection of the more immunogenic tumor. Furthermore, CD8 T cells in the more immunogenic tumor exhibit decreased effector function and increased resistance to PD-1 blockade, as tumor-infiltrating macrophages concurrently become more immunosuppressive. These results are highly suggestive of a “reverse abscopal effect,” by which immunologically “cold” tumors generate systemic immunosuppression that facilitate PD-1 immunotherapy resistance and immune escape of all other tumors in synchronous metastatic melanoma patients.AcknowledgementsWe would like to thank Dr. Marcus Bosenberg from the Department of Dermatology at Yale University for kindly gifting us with the YUMMER 1.7 murine melanoma cell line.Ethics ApprovalAnimal experiments were approved by the University Committee on Animal Resources and performed in accordance with University of Rochester approved guidelines.

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Divergent Impact of Glucose Availability on Human Virus-Specific and Generically Activated CD8 T Cells

Metabolites ◽

10.3390/metabo10110461 ◽

2020 ◽

Vol 10 (11) ◽

pp. 461

Author(s):

Jenifer Sanchez ◽

Ian Jackson ◽

Katie R. Flaherty ◽

Tamara Muliaditan ◽

Anna Schurich

Keyword(s):

Immune Response ◽

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Cell Function ◽

Cd8 T Cell ◽

Cell Immune Response ◽

Complex Nature ◽

Human Virus ◽

Glucose Availability

Upon activation T cells engage glucose metabolism to fuel the costly effector functions needed for a robust immune response. Consequently, the availability of glucose can impact on T cell function. The glucose concentrations used in conventional culture media and common metabolic assays are often artificially high, representing hyperglycaemic levels rarely present in vivo. We show here that reducing glucose concentration to physiological levels in culture differentially impacted on virus-specific compared to generically activated human CD8 T cell responses. In virus-specific T cells, limiting glucose availability significantly reduced the frequency of effector-cytokine producing T cells, but promoted the upregulation of CD69 and CD103 associated with an increased capacity for tissue retention. In contrast the functionality of generically activated T cells was largely unaffected and these showed reduced differentiation towards a residency phenotype. Furthermore, T cells being cultured at physiological glucose concentrations were more susceptible to viral infection. This setting resulted in significantly improved lentiviral transduction rates of primary cells. Our data suggest that CD8 T cells are exquisitely adapted to their niche and provide a reminder of the need to better mimic physiological conditions to study the complex nature of the human CD8 T cell immune response.

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Fas-mediated apoptosis of CD4+ and CD8+ T cells from human immunodeficiency virus-infected persons: differential in vitro preventive effect of cytokines and protease antagonists

Blood ◽

10.1182/blood.v87.12.4959.bloodjournal87124959 ◽

1996 ◽

Vol 87 (12) ◽

pp. 4959-4966 ◽

Cited By ~ 144

Author(s):

J Estaquier ◽

M Tanaka ◽

T Suda ◽

S Nagata ◽

P Golstein ◽

...

Keyword(s):

T Cells ◽

Cell Death ◽

T Cell ◽

Cd8 T Cells ◽

Cd8 T Cell ◽

Cd4 T Cell ◽

Death Process ◽

T Cell Apoptosis ◽

Soluble Fas ◽

Immunodeficiency Syndrome

Human immunodeficiency syndrome (HIV) infection leads to a progressive loss of T-cell-mediated immunity associated with T-cell apoptosis. We report here that CD4+ and CD8+ T cells from HIV-1-infected persons are sensitive to Fas (CD95/APO-1)-mediated death induced either by an agonistic anti-Fas antibody or by the physiologic soluble Fas ligand, although showing no sensitivity to tumor necrosis factor alpha-induced death. CD4+ and CD8+ T-cell apoptosis induced by Fas ligation was enhanced by inhibitors of protein synthesis and was prevented either by a soluble Fas receptor decoy or an antagonistic anti-Fas antibody. Fas- mediated apoptosis could also be prevented in a CD4+ or CD8+ T-cell- type manner (1) by several protease antagonists, suggesting the involvement of the interleukin-1beta (IL-1beta)-converting enzyme (ICE)- related cysteine protease in CD4+ T-cell death and of both a CPP32- related cysteine protease and a calpain protease in CD8+ T-cell death; and (2) by three cytokines, IL-2, IL-12, and IL-10, that exerted their effects through a mechanism that required de novo protein synthesis. Finally, T-cell receptor (TCR)-induced apoptosis of CD4+ T cells from HIV-infected persons involved a Fas-mediated death process, whereas TCR stimulation of CD8+ T cells led to a different Fas-independent death process. These findings suggest that Fas-mediated T-cell death is involved in acquired immunodeficiency syndrome (AIDS) pathogenesis and that modulation of Fas-mediated signaling may represent a target for new therapeutic strategies aimed at the prevention of CD4+ T-cell death in AIDS.

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Cytomegalovirus inhibition of extrinsic apoptosis determines fitness and resistance to cytotoxic CD8 T cells

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1914667117 ◽

2020 ◽

Vol 117 (23) ◽

pp. 12961-12968 ◽

Cited By ~ 3

Author(s):

M. Zeeshan Chaudhry ◽

Rosaely Casalegno-Garduno ◽

Katarzyna M. Sitnik ◽

Bahram Kasmapour ◽

Ann-Kathrin Pulm ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Antigen Presentation ◽

Cd8 T Cells ◽

Cell Function ◽

Death Receptor ◽

Cd8 T Cell ◽

Cytotoxic T Cell ◽

Caspase 8 ◽

Infected Cells

Viral immune evasion is currently understood to focus on deflecting CD8 T cell recognition of infected cells by disrupting antigen presentation pathways. We evaluated viral interference with the ultimate step in cytotoxic T cell function, the death of infected cells. The viral inhibitor of caspase-8 activation (vICA) conserved in human cytomegalovirus (HCMV) and murine CMV (MCMV) prevents the activation of caspase-8 and proapoptotic signaling. We demonstrate the key role of vICA from either virus, in deflecting antigen-specific CD8 T cell-killing of infected cells. vICA-deficient mutants, lacking either UL36 or M36, exhibit greater susceptibility to CD8 T cell control than mutants lacking the set of immunoevasins known to disrupt antigen presentation via MHC class I. This difference is evident during infection in the natural mouse host infected with MCMV, in settings where virus-specific CD8 T cells are adoptively transferred. Finally, we identify the molecular mechanism through which vICA acts, demonstrating the central contribution of caspase-8 signaling at a point of convergence of death receptor-induced apoptosis and perforin/granzyme-dependent cytotoxicity.

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The Level of Viral Antigen Presented by Hepatocytes Influences CD8 T-Cell Function

Journal of Virology ◽

10.1128/jvi.02415-06 ◽

2007 ◽

Vol 81 (6) ◽

pp. 2940-2949 ◽

Cited By ~ 58

Author(s):

Adam J. Gehring ◽

Dianxing Sun ◽

Patrick T. F. Kennedy ◽

Esther Nolte-'t Hoen ◽

Seng Gee Lim ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Viral Antigen ◽

Cell Function ◽

Cd8 T Cell ◽

T Cell Function ◽

Tnf Α ◽

Antiviral Function ◽

Ifn Γ

ABSTRACT CD8 T cells exert their antiviral function through cytokines and lysis of infected cells. Because hepatocytes are susceptible to noncytolytic mechanisms of viral clearance, CD8 T-cell antiviral efficiency against hepatotropic viruses has been linked to their capacity to produce gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α). On the other hand, intrahepatic cytokine production triggers the recruitment of mononuclear cells, which sustain acute and chronic liver damage. Using virus-specific CD8 T cells and human hepatocytes, we analyzed the modulation of virus-specific CD8 T-cell function after recognition peptide-pulsed or virally infected hepatocytes. We observed that hepatocyte antigen presentation was generally inefficient, and the quantity of viral antigen strongly influenced CD8 T-cell antiviral function. High levels of hepatitis B virus production induced robust IFN-γ and TNF-α production in virus-specific CD8 T cells, while limiting amounts of viral antigen, both in hepatocyte-like cells and naturally infected human hepatocytes, preferentially stimulated CD8 T-cell degranulation. Our data document a mechanism where virus-specific CD8 T-cell function is influenced by the quantity of virus produced within hepatocytes.

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Inhibitory Effects of Lactic Acid on Human Antigen-Specific CD8+ T-Cells.

Blood ◽

10.1182/blood.v104.11.3844.3844 ◽

2004 ◽

Vol 104 (11) ◽

pp. 3844-3844

Author(s):

Marina Kreutz ◽

Karin Fischer ◽

Petra Hoffmann ◽

Simon Volkl ◽

Matthias Edinger ◽

...

Keyword(s):

T Cells ◽

Lactic Acid ◽

T Cell ◽

Cd8 T Cells ◽

Acid Production ◽

Cell Function ◽

Immune Escape ◽

Lactic Acid Production ◽

Target Cells ◽

Thymidine Uptake

Abstract A characteristic feature of inflammatory lesions or tumor sites is local acidosis, which is attributed to the local increase in lactic acid production. We studied the effect of such an acidic environment on the immune functions of antigen-specific CD8+ T-cells by incubating the cells in the presence of various concentrations of lactic acid for up to 48h. CD8+ T-cells were isolated from healthy donors and expanded by weekly stimulation with autologous dendritic cells pulsed with a mutated HLA-A2-binding Melan-A (ELAGIGILTV) peptide. The obtained T cell population consisted of at least 90% CD8+ and about 60% Melan-A specific T cells, as determined by Melan-A multimer staining. Incubation of CD8+ T cells with up to 20mM lactic acid for 24h did not cause T-cell apoptosis or cell death as determined by combined annexin/propidium iodide staining. However, the proliferative capacity of CD8+ T cells, as determined by 3H-thymidine uptake, was strongly inhibited. Similar results were obtained when we determined cytokine production and cytotoxic activity of the cells after a 24h culture period in 5-20 mM lactic acid. Production of both, IL-2 and IFN-gamma was strongly diminished in comparison to untreated cells, as determined by intracellular staining after stimulation with PMA/ionomycin for 5h in the presence of monensin. Analysis of the antigen-specific cytolytic capacity revealed that CD8+ T cells pre-cultured with lactic acid were less effective in killing antigen-loaded T2 target cells as compared to untreated CD8+ T cells. In parallel, the intracellular contents of the cytotoxic effector molecules granzyme-B and perforin was diminished. Re-adjusting the pH of the medium to a physiological value of pH7.4 could partially revert the effect of lactic acid. Treatment of CD8+ T cells with sodium lactate instead of lactic acid had no inhibitory effect. We conclude, that lactic acid is an important modulator of CD8+ T-cell function and may contribute, together with other factors, to immune escape mechanisms in the tumor environment.

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Histone Deacetylase 11 (HDAC11) Regulates Cytotoxic T-Cell Function and Memory Phenotype

Blood ◽

10.1182/blood.v120.21.840.840 ◽

2012 ◽

Vol 120 (21) ◽

pp. 840-840

Author(s):

David M Woods ◽

Karrune V. Woan ◽

Eva Sahakian ◽

John Powers ◽

Fengdong Cheng ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Cell Function ◽

Cd8 T Cell ◽

Central Memory ◽

Negative Regulator ◽

Wild Type ◽

Potential Target ◽

T Cell Function

Abstract Abstract 840 T-cells are an essential component of immune mediated tumor rejection. Adoptive transfer of T-cells results in a durable anti-tumor response in some patients with hematological malignancies. To further improve the efficacy of T-cell adoptive transfers, a better understanding of the regulatory checkpoints of these cells is needed. Here we show that HDAC11 is a negative regulator of CD8+ T-cell function, thus representing a potential target in adoptive immunotherapy. HDACs are a group of enzymes initially known for their role in deacetylating histones, thereby condensing chromatin structure and repressing gene expression. The known roles of HDACs as epigenetic regulators have recently expanded to include more complex regulatory functions including interactions with non-histone targets. HDAC11 is the most recently identified member of the HDAC family, and is highly expressed in brain, testis and T-cells. Recently, our group reported HDAC11 as a regulator of IL-10 production in antigen presenting cells. To determine the role of HDAC11 in T-cell biology, T-cells from HDAC11 knock out (HDAC11KO) mice were compared to wild-type T-cells in number, function and phenotype. HDAC11KO T-cells had no differences in absolute number or percentages of CD4+ or CD8+ lymphocytes. However CD8+ T-cells were hyper-proliferative upon CD3/CD28 stimulation and produced significantly higher levels of the pro-inflammatory, Tc1 cytokines IL-2, INF-γ, and TNF-α. However, no significant increases in the production of the Tc2 cytokines IL-4, IL-6 or IL-10 were seen. Further investigation of phenotypic differences also revealed that HDAC11KO mice have a larger percentage of central memory CD8+ T-cells. Additionally, HDAC11KO CD8+ T-cells express higher levels of the transcription factor Eomes, a known contributor to central memory cell formation as well as a controller of granzyme B and perforin production in CD8+ T-cells. This Tc1 and central memory-like phenotype translated to delayed tumor progression and survival in vivo in C1498 AML bearing mice treated with adoptively transferred HDAC11KO T-cells, as compared with wild type T-cells. Collectively, we have demonstrated HDAC11 as a negative regulator of CD8+ T-cell function, and a novel potential target to augment the efficacy of adoptive T-cell tumor immunotherapy. Disclosures: No relevant conflicts of interest to declare.

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