Tumor-Specific T Cells in Human Merkel Cell Carcinomas: A Possible Role for Tregs and T-Cell Exhaustion in Reducing T-Cell Responses

Johne's disease (paratuberculosis) is a chronic enteritis in cattle that is caused by intracellular infection withMycobacterium aviumsubsp.paratuberculosis. This infection is characterized by the functional exhaustion of T-cell responses toM. aviumsubsp.paratuberculosisantigens during late subclinical and clinical stages, presumably facilitating the persistence of this bacterium and the formation of clinical lesions. However, the mechanisms underlying T-cell exhaustion in Johne's disease are poorly understood. Thus, we performed expression and functional analyses of the immunoinhibitory molecules programmed death-1 (PD-1)/PD-ligand 1 (PD-L1) and lymphocyte activation gene 3 (LAG-3)/major histocompatibility complex class II (MHC-II) inM. aviumsubsp.paratuberculosis-infected cattle during the late subclinical stage. Flow cytometric analyses revealed the upregulation of PD-1 and LAG-3 in T cells in infected animals, which suffered progressive suppression of interferon gamma (IFN-γ) responses to theM. aviumsubsp.paratuberculosisantigen. In addition, PD-L1 and MHC-II were expressed on macrophages from infected animals, consistent with PD-1 and LAG-3 pathways contributing to the suppression of IFN-γ responses during the subclinical stages ofM. aviumsubsp.paratuberculosisinfection. Furthermore, dual blockade of PD-L1 and LAG-3 enhancedM. aviumsubsp.paratuberculosis-specific IFN-γ responses in blood from infected animals, andin vitroLAG-3 blockade enhanced IFN-γ production fromM. aviumsubsp.paratuberculosis-specific CD4+and CD8+T cells. Taken together, the present data indicate thatM. aviumsubsp.paratuberculosis-specific T-cell exhaustion is in part mediated by PD-1/PD-L1 and LAG-3/MHC-II interactions and that LAG-3 is a molecular target for the control ofM. aviumsubsp.paratuberculosis-specific T-cell responses.

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Phenotypic and functional differences of HBV core-specific versus HBV polymerase-specific CD8+ T cells in chronically HBV-infected patients with low viral load

Gut ◽

10.1136/gutjnl-2018-316641 ◽

2019 ◽

Vol 68 (5) ◽

pp. 905-915 ◽

Cited By ~ 37

Author(s):

Anita Schuch ◽

Elahe Salimi Alizei ◽

Kathrin Heim ◽

Dominik Wieland ◽

Michael Muthamia Kiraithe ◽

...

Keyword(s):

T Cells ◽

Viral Load ◽

T Cell ◽

Cd8 T Cells ◽

Molecular Mechanisms ◽

T Cell Responses ◽

T Cell Exhaustion ◽

Detection Rates ◽

Cell Exhaustion ◽

Cell Responses

ObjectiveA hallmark of chronic HBV (cHBV) infection is the presence of impaired HBV-specific CD8+ T cell responses. Functional T cell exhaustion induced by persistent antigen stimulation is considered a major mechanism underlying this impairment. However, due to their low frequencies in chronic infection, it is currently unknown whether HBV-specific CD8+ T cells targeting different epitopes are similarly impaired and share molecular profiles indicative of T cell exhaustion.DesignBy applying peptide-loaded MHC I tetramer-based enrichment, we could detect HBV-specific CD8+ T cells targeting epitopes in the HBV core and the polymerase proteins in the majority of 85 tested cHBV patients with low viral loads. Lower detection rates were obtained for envelope-specific CD8+ T cells. Subsequently, we performed phenotypic and functional in-depth analyses.ResultsHBV-specific CD8+ T cells are not terminally exhausted but rather exhibit a memory-like phenotype in patients with low viral load possibly reflecting weak ongoing cognate antigen recognition. Moreover, HBV-specific CD8+ T cells targeting core versus polymerase epitopes significantly differed in frequency, phenotype and function. In particular, in comparison with core-specific CD8+ T cells, a higher frequency of polymerase-specific CD8+ T cells expressed CD38, KLRG1 and Eomes accompanied by low T-bet expression and downregulated CD127 indicative of a more severe T cell exhaustion. In addition, polymerase-specific CD8+ T cells exhibited a reduced expansion capacity that was linked to a dysbalanced TCF1/BCL2 expression.ConclusionsOverall, the molecular mechanisms underlying impaired T cell responses differ with respect to the targeted HBV antigens. These results have potential implications for immunotherapeutic approaches in HBV cure.

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Cooperation of PD-1 and LAG-3 Contributes to T-Cell Exhaustion in Anaplasma marginale-Infected Cattle

Infection and Immunity ◽

10.1128/iai.00278-16 ◽

2016 ◽

Vol 84 (10) ◽

pp. 2779-2790 ◽

Cited By ~ 19

Author(s):

Tomohiro Okagawa ◽

Satoru Konnai ◽

James R. Deringer ◽

Massaro W. Ueti ◽

Glen A. Scoles ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Outer Membrane Proteins ◽

T Cell Responses ◽

Anaplasma Marginale ◽

T Cell Exhaustion ◽

Content Type ◽

Cell Exhaustion ◽

Cell Responses ◽

Ifn Γ

The CD4+T-cell response is central for the control ofAnaplasma marginaleinfection in cattle. However, the infection induces a functional exhaustion of antigen-specific CD4+T cells in cattle immunized withA. marginaleouter membrane proteins or purified outer membranes (OMs), which presumably facilitates the persistence of this rickettsia. In the present study, we hypothesize that T-cell exhaustion following infection is induced by the upregulation of immunoinhibitory receptors on T cells, such as programmed death 1 (PD-1) and lymphocyte activation gene 3 (LAG-3). OM-specific T-cell responses and the kinetics of PD-1-positive (PD-1+) LAG-3+exhausted T cells were monitored inA. marginale-challenged cattle previously immunized with OMs. Consistent with data from previous studies, OM-specific proliferation of peripheral blood mononuclear cells (PBMCs) and interferon gamma (IFN-γ) production were significantly suppressed in challenged animals by 5 weeks postinfection (wpi). In addition, bacteremia and anemia also peaked in these animals at 5 wpi. Flow cytometric analysis revealed that the percentage of PD-1+LAG-3+T cells in the CD4+, CD8+, and γδ T-cell populations gradually increased and also peaked at 5 wpi. A large increase in the percentage of LAG-3+γδ T cells was also observed. Importantly,in vitro, the combined blockade of the PD-1 and LAG-3 pathways partially restored OM-specific PBMC proliferation and IFN-γ production at 5 wpi. Taken together, these results indicate that coexpression of PD-1 and LAG-3 on T cells contributes to the rapid exhaustion ofA. marginale-specific T cells following infection and that these immunoinhibitory receptors regulate T-cell responses during bovine anaplasmosis.

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Delayed Expression of PD-1 and TIGIT on HIV-Specific CD8 T Cells in Untreated HLA-B*57:01 Individuals Followed from Early Infection

Journal of Virology ◽

10.1128/jvi.02128-19 ◽

2020 ◽

Vol 94 (14) ◽

Cited By ~ 1

Author(s):

Lydia Scharf ◽

Johanna Tauriainen ◽

Marcus Buggert ◽

Wendy Hartogensis ◽

David J. Nolan ◽

...

Keyword(s):

T Cell ◽

T Cell Responses ◽

Hla Class I ◽

Cd8 T Cell ◽

Receptor Expression ◽

T Cell Exhaustion ◽

Inhibitory Receptor ◽

Cell Exhaustion ◽

Cell Responses ◽

Immunomodulatory Therapies

ABSTRACT While the relationship of protective human leukocyte antigen (HLA) class I alleles and HIV progression is well defined, the interaction of HLA-mediated protection and CD8 T-cell exhaustion is less well characterized. To gain insight into the influence of HLA-B*57:01 on the deterioration of CD8 T-cell responses during HIV infection in the absence of antiretroviral treatment, we compared HLA-B*57:01-restricted HIV-specific CD8 T-cell responses to responses restricted by other HLA class I alleles longitudinally after control of peak viremia. Detailed characterization of polyfunctionality, differentiation phenotypes, transcription factor, and inhibitory receptor expression revealed progression of CD8 T-cell exhaustion over the course of the infection in both patient groups. However, early effects on the phenotype of the total CD8 T-cell population were apparent only in HLA-B*57-negative patients. The HLA-B*57:01-restricted, HIV epitope-specific CD8 T-cell responses showed beneficial functional patterns and significantly lower frequencies of inhibitory receptor expression, i.e., PD-1 and coexpression of PD-1 and TIGIT, within the first year of infection. Coexpression of PD-1 and TIGIT was correlated with clinical markers of disease progression and declining percentages of the T-bethi Eomesdim CD8 T-cell population. In accordance with clinical and immunological deterioration in the HLA-B*57:01 group, the difference in PD-1 and TIGIT receptor expression did not persist to later stages of the disease. IMPORTANCE Given the synergistic nature of TIGIT and PD-1, the coexpression of those inhibitory receptors should be considered when evaluating T-cell pathogenesis, developing immunomodulatory therapies or vaccines for HIV, and when using immunotherapy or vaccination for other causes in HIV-infected patients. HIV-mediated T-cell exhaustion influences the patient´s disease progression, immune system and subsequently non-AIDS complications, and efficacy of vaccinations against other pathogens. Consequently, the possibilities of interfering with exhaustion are numerous. Expanding the use of immunomodulatory therapies to include HIV treatment depends on information about possible targets and their role in the deterioration of the immune system. Furthermore, the rise of immunotherapies against cancer and elevated cancer incidence in HIV-infected patients together increase the need for detailed knowledge of T-cell exhaustion and possible interactions. A broader approach to counteract immune exhaustion to alleviate complications and improve efficacy of other vaccines also promises to increase patients’ health and quality of life.

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Targeting PD-1 and Tim-3 Pathways to Reverse CD8 T-Cell Exhaustion and Enhance Ex Vivo T-Cell Responses to Autologous Dendritic/Tumor Vaccines

Journal of Immunotherapy ◽

10.1097/cji.0000000000000122 ◽

2016 ◽

Vol 39 (4) ◽

pp. 171-180 ◽

Cited By ~ 34

Author(s):

Jingwei Liu ◽

Shurong Zhang ◽

Yuefeng Hu ◽

Zhaomin Yang ◽

Jingpo Li ◽

...

Keyword(s):

T Cell ◽

Ex Vivo ◽

T Cell Responses ◽

Cd8 T Cell ◽

T Cell Exhaustion ◽

Tumor Vaccines ◽

Cell Exhaustion ◽

Cell Responses

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Impact of Epitope Escape on PD-1 Expression and CD8 T-Cell Exhaustion during Chronic Infection

Journal of Virology ◽

10.1128/jvi.02524-08 ◽

2009 ◽

Vol 83 (9) ◽

pp. 4386-4394 ◽

Cited By ~ 99

Author(s):

Joseph N. Blattman ◽

E. John Wherry ◽

Sang-Jun Ha ◽

Robbert G. van der Most ◽

Rafi Ahmed

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Viral Infections ◽

Viral Clearance ◽

T Cell Exhaustion ◽

Wild Type ◽

Cell Exhaustion ◽

Cell Responses ◽

Functional Inactivation

ABSTRACT During some persistent viral infections, virus-specific T-cell responses wane due to the antigen-specific deletion or functional inactivation (i.e., exhaustion) of responding CD8 T cells. T-cell exhaustion often correlates with high viral load and is associated with the expression of the inhibitory receptor PD-1. In other infections, functional T cells are observed despite high levels of pathogen persistence. The reasons for these different T-cell fates during chronic viral infections are not clear. Here, we tracked the fate of virus-specific CD8 T cells in lymphocytic choriomeningitis virus (LCMV)-infected mice during viral clearance, the persistence of wild-type virus, or the selection and persistence of a viral variant that abrogates the presentation of a single epitope. Viral clearance results in PD-1lo functional virus-specific CD8 T cells, while the persistence of wild-type LCMV results in high PD-1 levels and T-cell exhaustion. However, following the emergence of a GP35V→A variant virus that abrogates the presentation of the GP33 epitope, GP33-specific CD8 T cells remained functional, continued to show low levels of PD-1, and reexpressed CD127, a marker of memory T-cell differentiation. In the same animals and under identical environmental conditions, CD8 T cells recognizing nonmutated viral epitopes became physically deleted or were PD-1hi and nonfunctional. Thus, the upregulation of PD-1 and the functional inactivation of virus-specific T cells during chronic viral infection is dependent upon continued epitope recognition. These data suggest that optimal strategies for vaccination should induce high-magnitude broadly specific T-cell responses that prevent cytotoxic T-lymphocyte escape and highlight the need to evaluate the function of vaccine-induced T cells in the context of antigens presented during virus persistence.

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T-Cell Responses in Merkel Cell Carcinoma: Implications for Improved Immune Checkpoint Blockade and Other Therapeutic Options

International Journal of Molecular Sciences ◽

10.3390/ijms22168679 ◽

2021 ◽

Vol 22 (16) ◽

pp. 8679

Author(s):

Laura Gehrcken ◽

Tatjana Sauerer ◽

Niels Schaft ◽

Jan Dörrie

Keyword(s):

T Cells ◽

T Cell ◽

Cell Carcinoma ◽

Merkel Cell Carcinoma ◽

Immune Checkpoint ◽

Checkpoint Inhibitors ◽

T Cell Responses ◽

Therapeutic Options ◽

Merkel Cell ◽

Cell Responses

Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer with rising incidence and high mortality. Approximately 80% of the cases are caused by the human Merkel cell polyomavirus, while the remaining 20% are induced by UV light leading to mutations. The standard treatment of metastatic MCC is the use of anti-PD-1/-PD-L1-immune checkpoint inhibitors (ICI) such as Pembrolizumab or Avelumab, which in comparison with conventional chemotherapy show better overall response rates and longer duration of responses in patients. Nevertheless, 50% of the patients do not respond or develop ICI-induced, immune-related adverse events (irAEs), due to diverse mechanisms, such as down-regulation of MHC complexes or the induction of anti-inflammatory cytokines. Other immunotherapeutic options such as cytokines and pro-inflammatory agents or the use of therapeutic vaccination offer great ameliorations to ICI. Cytotoxic T-cells play a major role in the effectiveness of ICI, and tumour-infiltrating CD8+ T-cells and their phenotype contribute to the clinical outcome. This literature review presents a summary of current and future checkpoint inhibitor therapies in MCC and demonstrates alternative therapeutic options. Moreover, the importance of T-cell responses and their beneficial role in MCC treatment is discussed.

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TIMs: central regulators of immune responses

Journal of Experimental Medicine ◽

10.1084/jem.20082429 ◽

2008 ◽

Vol 205 (12) ◽

pp. 2699-2701 ◽

Cited By ~ 49

Author(s):

David A. Hafler ◽

Vijay Kuchroo

Keyword(s):

T Cells ◽

T Cell ◽

Hiv Infection ◽

Viral Infections ◽

Opportunistic Infections ◽

T Cell Exhaustion ◽

Cell Exhaustion ◽

Cell Responses ◽

Chronic Viral Infections ◽

Chronic Hiv Infection

Exhaustion of T cell responses during chronic viral infections has been observed in both mouse and man and has been attributed to up-regulation of PD-1 on the surface of exhausted T cells. In patients with chronic human HIV infection, T cell exhaustion leads to opportunistic infections associated with AIDS. However, not all the exhausted T cells express PD-1, suggesting that other molecules may be involved in the phenotype. A new study now demonstrates a central role for T cell immunoglobulin and mucin domain–containing protein-3 (TIM-3) in T cell exhaustion during chronic HIV infection and suggests that TIM-3 may be a novel therapeutic target in chronic viral diseases.

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857 LAMP1 targeting of the large T antigen of merkel cell polyomavirus elicits potent CD4+ T cell responses and prevents tumor growth

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-sitc2020.0857 ◽

2020 ◽

Vol 8 (Suppl 3) ◽

pp. A910-A910

Author(s):

Claire Buchta Rosean ◽

Pratima Sinha ◽

David Koelle ◽

Paul Nghiem ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Cd4 T Cells ◽

T Cell Responses ◽

T Antigen ◽

T Cell Response ◽

Cd4 T Cell ◽

Merkel Cell ◽

Cell Responses

BackgroundThe majority of Merkel cell carcinomas (MCC), a rare and highly-aggressive type of neuroendocrine skin cancer, are associated with Merkel cell polyomavirus (MCPyV) infection. MCPyV integrates into the host genome, resulting in expression of a truncated form of the viral large T antigen (LT) in infected cells, and making LT an attractive target for therapeutic cancer vaccines. While induction of tumor-reactive CD8+ T cells is a major goal of cancer therapy, CD4+ T cells provide essential support to CD8+ T cells by promoting their expression of cytotoxic effector molecules and increasing their migratory capacity. Cytokines secreted by CD4+ T cells, such as IFNγ, can also exert desirable effects on the tumor microenvironment. Therefore, we set out to design a cancer vaccine that promotes potent, antigen-specific CD4+ T cell responses to MCPyV-LT.MethodsTo activate antigen-specific CD4+ T cells in vivo, we utilized our nucleic acid platform, UNITE (UNiversal Intracellular Targeted Expression), which fuses a tumor-associated antigen with lysosomal-associated membrane protein 1 (LAMP1). This lysosomal targeting technology results in enhanced antigen presentation and a balanced T cell response. LTS220A, encoding a mutated form of MCPyV-LT that abrogates its pro-oncogenic properties, was introduced into the UNITE platform. LTS220A-UNITE, known as ITI-3000, was administered to female C57BL/6 mice intradermally in the ear with electroporation.ResultsITI-3000 promoted a potent, antigen-specific CD4+ T cell response to MCPyV-LT. Vaccination with ITI-3000 significantly delayed and slowed growth of B16F10 tumors expressing LTS220A in prophylactic and therapeutic settings, respectively. ITI-3000 induced a favorable tumor microenvironment (TME), including significantly enhanced numbers of CD4+ T cells, CD8+ T cells, NK cells, and NKT cells. Tumor-infiltrating myeloid cells were reduced in frequency in vaccinated mice and polarized towards an anti-tumor phenotype. Cytokine analysis of the TME showed significantly enhanced levels of cytokines associated with anti-tumor immune responses in ITI-3000-vaccinated mice, including IFNγ, TNFα, IL-2, and IL-1β. Additionally, ITI-3000 synergized with PD-1 blockade, further reducing tumor burden and enhancing survival in mice receiving combination therapy.ConclusionsWe find that DNA vaccination with ITI-3000 using the UNITE platform enhances CD4+ T cell responses to MCPyV-LT and results in anti-tumor immune responses in a mouse model of Merkel cell carcinoma.Ethics ApprovalThis study was approved by Immunomic Therapeutics’ Institutional Animal Care and Use Committee, protocol number 16-11-002.

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