scholarly journals The Proteasome Immunosubunit Multicatalytic Endopeptidase Complex-Like 1 Is a T-Cell-Intrinsic Factor Influencing Homeostatic Expansion

2007 ◽  
Vol 76 (3) ◽  
pp. 1207-1213 ◽  
Author(s):  
Dietmar M. W. Zaiss ◽  
Natascha de Graaf ◽  
Alice J. A. M. Sijts
Keyword(s):  
Bone Marrow ◽  
T Cell ◽  
Cell Population ◽  
Antigen Processing ◽  
Cd8 T Cell ◽  
Lymphoid Organs ◽  
T Cell Subsets ◽  
Class I Mhc ◽  
Mhc I ◽  
Deficient Mice

ABSTRACT Homeostatic regulatory mechanisms maintain the constant ratios between different lymphocyte subsets in the secondary lymphoid organs. How this dynamic equilibrium is achieved, in particular following the clonal expansion and subsequent contraction of different cells after infection, remains poorly understood. Expression of the proteasome immunosubunits has been shown to influence not only major histocompatibility complex class I (MHC-I) antigen processing and thereby T-cell responses, but also the CD4/CD8 T-cell ratios in lymphoid organs. We examined the relationships between these different immunosubunit-mediated effects in mice of various proteasome subunit compositions during infection with Listeria monocytogenes. Mice that lacked the immunosubunit multicatalytic endopeptidase complex-like 1 (MECL-1) maintained enhanced CD4/CD8 T-cell ratios during infection, while MHC-I surface levels resembled those in wild-type (wt) mice. LMP7 gene-deficient mice, on the other hand, showed reduced MHC-I expression, while their splenic CD4/CD8 ratios were similar to those in wt mice. Remarkably, analysis of bone marrow-chimeric immunosubunit gene-deficient mice, reconstituted with a mixture of wt and LMP7- plus MECL-1-deficient bone marrow, revealed that the LMP7- plus MECL-1-deficient T-cell population maintained a higher CD4/CD8 T-cell ratio than the wt T-cell population before, during, and after infection and T-cell memory formation. Since in these mice the immunosubunit-positive and immunosubunit-negative T-cell populations were selected in the same thymus and expanded in the same lymphoid environments, our findings indicate that MECL-1 influences the homeostatic equilibrium between T-cell subsets, not through indirect extracellular signals, such as MHC-I expression or the cytokine milieu, but through direct effects on T-cell-intrinsic processes.

scholarly journals IFN-γ treatment protocol for MHC-Ilo/PD-L1+ pancreatic tumor cells selectively restores their TAP-mediated presentation competence and CD8 T-cell priming potential

2020 ◽  
Vol 8 (2) ◽  
pp. e000692
Author(s):  
Katja Stifter ◽  
Jana Krieger ◽  
Leonie Ruths ◽  
Johann Gout ◽  
Medhanie Mulaw ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cancer Cells ◽  
Cd8 T Cells ◽  
Antigen Processing ◽  
Treatment Protocol ◽  
Cd8 T Cell ◽  
Mhc I ◽  
Ifn Γ ◽  
Deficient Mice

BackgroundMany cancer cells express a major histocompatibility complex class I low/ programmed cell death 1 ligand 1 positive (MHC-Ilo/PD-L1+) cell surface profile. For immunotherapy, there is, thus, an urgent need to restore presentation competence of cancer cells with defects in MHC-I processing/presentation combined with immune interventions that tackle the tumor-initiated PD-L1/PD-1 signaling axis. Using pancreatic ductal adenocarcinoma cells (PDACCs) as a model, we here explored if (and how) expression/processing of tumor antigens via transporters associated with antigen processing (TAP) affects priming of CD8 T cells in PD-1/PD-L1-competent/-deficient mice.MethodsWe generated tumor antigen-expressing vectors, immunized TAP-competent/-deficient mice and determined de novo primed CD8 T-cell frequencies by flow cytometry. Similarly, we explored the antigenicity and PD-L1/PD-1 sensitivity of PDACCs versus interferon-γ (IFN-γ)-treated PDACCs in PD-1/PD-L1-competent/deficient mice. The IFN-γ-induced effects on gene and cell surface expression profiles were determined by microarrays and flow cytometry.ResultsWe identified two antigens (cripto-1 and an endogenous leukemia virus-derived gp70) that were expressed in the Endoplasmic Reticulum (ER) of PDACCs and induced CD8 T-cell responses either independent (Cripto-1:Kb/Cr16-24) or dependent (gp70:Kb/p15E) on TAP by DNA immunization. IFN-γ-treatment of PDACCs in vitro upregulated MHC-I- and TAP- but also PD-L1-expression. Mechanistically, PD-L1/PD-1 signaling was superior to the reconstitution of MHC-I presentation competence, as subcutaneously transplanted IFN-γ-treated PDACCs developed tumors in C57BL/6J and PD-L1-/- but not in PD-1-/- mice. Using PDACCs, irradiated at day 3 post-IFN-γ-treatment or PD-L1 knockout PDACCs as vaccines, we could selectively bypass upregulation of PD-L1, preferentially induce TAP-dependent gp70:Kb/p15E-specific CD8 T cells associated with a weakened PD-1+ exhaustion phenotype and reject consecutively injected tumor transplants in C57BL/6J mice.ConclusionsThe IFN-γ-treatment protocol is attractive for cell-based immunotherapies, because it restores TAP-dependent antigen processing in cancer cells, facilitates priming of TAP-dependent effector CD8 T-cell responses without additional check point inhibitors and could be combined with genetic vaccines that complement priming of TAP-independent CD8 T cells.

scholarly journals Conditional deletion of cytokine receptor chains reveals that IL-7 and IL-15 specify CD8 cytotoxic lineage fate in the thymus

2012 ◽  
Vol 209 (12) ◽  
pp. 2263-2276 ◽  
Author(s):  
Tom M. McCaughtry ◽  
Ruth Etzensperger ◽  
Amala Alag ◽  
Xuguang Tai ◽  
Sema Kurtulus ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Conditional Knockout ◽  
Cytokine Receptor ◽  
T Cell Subsets ◽  
Cytotoxic T Cell ◽  
Lineage Specification ◽  
Class I Mhc ◽  
Mhc I

The thymus generates T cells with diverse specificities and functions. To assess the contribution of cytokine receptors to the differentiation of T cell subsets in the thymus, we constructed conditional knockout mice in which IL-7Rα or common cytokine receptor γ chain (γc) genes were deleted in thymocytes just before positive selection. We found that γc expression was required to signal the differentiation of MHC class I (MHC-I)–specific thymocytes into CD8+ cytotoxic lineage T cells and into invariant natural killer T cells but did not signal the differentiation of MHC class II (MHC-II)–specific thymocytes into CD4+ T cells, even into regulatory Foxp3+CD4+ T cells which require γc signals for survival. Importantly, IL-7 and IL-15 were identified as the cytokines responsible for CD8+ cytotoxic T cell lineage specification in vivo. Additionally, we found that small numbers of aberrant CD8+ T cells expressing Runx3d could arise without γc signaling, but these cells were developmentally arrested before expressing cytotoxic lineage genes. Thus, γc-transduced cytokine signals are required for cytotoxic lineage specification in the thymus and for inducing the differentiation of MHC-I–selected thymocytes into functionally mature T cells.

Platelet MHC Class I Mediates CD8+ T Cell Suppression During Sepsis

Blood ◽  
2021 ◽  
Author(s):  
Li Guo ◽  
Sikui Shen ◽  
Jesse W Rowley ◽  
Neal D. Tolley ◽  
Wenwen Jia ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Ex Vivo ◽  
Cd8 T Cell ◽  
Class I ◽  
Functional Responses ◽  
Class I Mhc ◽  
Mhc I

Circulating platelets interact with leukocytes to modulate host immune and thrombotic responses. In sepsis, platelet-leukocyte interactions are increased, and have been associated with adverse clinical events, including increased platelet-T cell interactions. Sepsis is associated with reduced CD8+ T cell numbers and functional responses, but whether platelets regulate CD8+ T cell responses during sepsis remains unknown. In our current study, we systemically evaluated platelet antigen internalization and presentation through major histocompatibility complex class I (MHC-I) and their effects on antigen specific CD8+ T cells in sepsis in vivo and ex vivo. We discovered that both human and murine platelets internalize and proteolyze exogenous antigens, generating peptides that are loaded onto MHC-I. The expression of platelet MHC-I, but not platelet MHC-II, is significantly increased in human and murine platelets during sepsis and in human megakaryocytes stimulated with agonists generated systemically during sepsis (e.g., IFN-g and LPS). Upregulation of platelet MHC-I during sepsis increases antigen cross-presentation and interactions with CD8+ T cells in an antigen-specific manner. Using a platelet lineage specific MHC-I deficient mouse strain (B2mf/f--Pf4Cre), we demonstrate that platelet MHC-I regulates antigen-specific CD8+ T cell proliferation in vitro, as well as the number and functional responses of CD8+ T cells in vivo during sepsis. Loss of platelet MHC-I reduced sepsis-associated mortality in mice in an antigen specific setting. These data identify a new mechanism by which platelets, through MHC-I, process and cross-present antigens, engage antigen specific CD8+ T cells, and regulate CD8+ T cell number, functional responses, and outcomes during sepsis.

scholarly journals Differential Antigen Presentation Kinetics of CD8+ T-Cell Epitopes Derived from the Same Viral Protein

2008 ◽  
Vol 82 (18) ◽  
pp. 9293-9298 ◽  
Author(s):  
Jonah B. Sacha ◽  
Matthew R. Reynolds ◽  
Matthew B. Buechler ◽  
Chungwon Chung ◽  
Anna K. Jonas ◽  
...  
Keyword(s):  
T Cell ◽  
Viral Protein ◽  
Cd8 T Cell ◽  
T Cell Epitopes ◽  
Complex Class ◽  
Class I Mhc ◽  
Mhc I ◽  
Histocompatibility Complex ◽  
Peptide Presentation ◽  
Kinetics Of

ABSTRACT The kinetics of peptide presentation by major histocompatibility complex class I (MHC-I) molecules may contribute to the efficacy of CD8+ T cells. Whether all CD8+ T-cell epitopes from a protein are presented by the same MHC-I molecule with similar kinetics is unknown. Here we show that CD8+ T-cell epitopes derived from SIVmac239 Gag are presented with markedly different kinetics. We demonstrate that this discrepancy in presentation is not related to immunodominance but instead is due to differential requirements for epitope generation. These results illustrate that significant differences in presentation kinetics can exist among CD8+ T-cell epitopes derived from the same viral protein.

170 Microfluidics cell squeezing enables potent cellular vaccines in murine models through direct cytosolic loading and direct CD8 T cell priming

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A184-A184
Author(s):  
Emrah Ozay ◽  
Matthew Booty ◽  
Katarina Blagovic ◽  
David Soto ◽  
Olivia Pryor ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Median Survival ◽  
Cd8 T Cells ◽  
Mononuclear Cells ◽  
Cd8 T Cell ◽  
Laboratory Animals ◽  
Peripheral Blood Mononuclear ◽  
Class I Mhc ◽  
Mhc I

BackgroundThe presentation of sufficient antigen on major histocompatibility complex class I (MHC-I) is essential to prime CD8+ T cells.MethodsTo achieve efficient MHC-I presentation, we used microfluidics cell squeezing (Cell Squeeze®) to deliver antigens directly to the cytosol of antigen presenting cells (APCs), bypassing the need for cross-presentation. In addition to facilitating priming by professional APCs, this approach enables lymphocytic subsets within peripheral blood mononuclear cells (PBMCs) to function as unconventional APCs in mouse preclinical models.ResultsWe demonstrated that microfluidic cell squeezing delivers cargo to major cell populations within splenocytes (T cells, B cells, NK cells, and monocytes) and that protein, peptide, or mRNA antigens are rapidly processed and presented. In vivo, squeezed splenocytes directly presented antigen to CD8+ T cells. In the TC-1 tumor model for HPV+ cancers, squeezed splenocytes completely protect mice when administered prophylactically, protecting 15/15 animals from primary challenge and 11/15 animals from tumor re-challenge. Following therapeutic administration, squeezed splenocytes significantly improved median survival time to 56 days from 28 days, as observed with untreated controls. Immunization can also be combined with chemotherapy to further enhance therapeutic efficacy, improving median survival to over 100 days compared to 81 days with SQZ monotherapy or 32 days with chemotherapy alone. When tumor infiltrating lymphocytes (TILs) were analyzed following therapeutic immunization, squeezed splenocyte immunization elicited a significant influx of antigen specific CD8+ T cells: with SQZ treatment, ~87% of tumor-infiltrating CD8 T cells were antigen-specific, as measured by an E7-tetramer stain, while only ~33.6% and ~1.15% of infiltrating CD8 T cells were specific for E7 with subcutaneous peptide vaccination and no treatment, respectively.ConclusionsThrough the direct cytosolic delivery of antigen, we have engineered unfractionated PBMCs to function as potent APCs. This strategy generates potent antigen-specific CD8+ T cell responses in mouse models. Taken together, these findings support the potential of SQZ-PBMCs as an effective antigen-specific vaccination strategy against cancer. SQZ-PBMC-HPV is currently under clinical evaluation for HPV16+ tumor indications.Ethics ApprovalAll methods were performed in accordance with relevant guidelines and regulations; Animal studies were approved by the Institutional Animal Care and Use Committee (IACUC) at SQZ Biotechnologies, using the recommendations from the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health and the Office of Laboratory Animal Welfare. All activities were also conducted in accordance with Public Health Service (PHS) Policy on Humane Use and Care of Laboratory Animals.

scholarly journals The role of cDC1s in vivo: CD8 T cell priming through cross-presentation

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 98 ◽  
Author(s):  
Derek Theisen ◽  
Kenneth Murphy
Keyword(s):  
Bone Marrow ◽  
Dendritic Cells ◽  
T Cell ◽  
Antigen Processing ◽  
Molecular Mechanisms ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Cross Presentation ◽  
Cell Responses

The cDC1 subset of classical dendritic cells is specialized for priming CD8 T cell responses through the process of cross-presentation. The molecular mechanisms of cross-presentation remain incompletely understood because of limited biochemical analysis of rare cDC1 cells, difficulty in their genetic manipulation, and reliance onin vitrosystems based on monocyte- and bone-marrow-derived dendritic cells. This review will discuss cross-presentation from the perspective of studies with monocyte- or bone-marrow-derived dendritic cells while highlighting the need for future work examining cDC1 cells. We then discuss the role of cDC1s as a cellular platform to combine antigen processing for class I and class II MHC presentation to allow the integration of “help” from CD4 T cells during priming of CD8 T cell responses.

scholarly journals Self MHC class I–licensed NK cells enhance adaptive CD8 T-cell viral immunity

Blood ◽  
2011 ◽  
Vol 117 (19) ◽  
pp. 5133-5141 ◽  
Author(s):  
Michael D. Stadnisky ◽  
Xuefang Xie ◽  
Ebony R. Coats ◽  
Timothy N. Bullock ◽  
Michael G. Brown
Keyword(s):  
T Cells ◽  
T Cell ◽  
Nk Cells ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
Cd8 T Cell ◽  
Class I ◽  
Inhibitory Receptor ◽  
Class I Mhc ◽  
Mhc I

AbstractMHC class I (MHC I) is essential to NK- and T-cell effector and surveillance functions. However, it is unknown whether MHC I polymorphism influences adaptive immunity through NK cells. Previously, we found that MHC I Dk, a cognate ligand for the Ly49G2 inhibitory receptor, was essential to NK control of murine (M)CMV infection. Here we assessed the significance of NK inhibitory receptor recognition of MCMV on CD8 T cells in genetically defined MHC I Dk disparate mice. We observed that Dk-licensed Ly49G2+ NK cells stabilized and then enhanced conventional dendritic cells (cDCs) recovery after infection. Furthermore, licensed NK support of cDC recovery was essential to enhance the tempo, magnitude, and effector activity of virus-specific CD8 T cells. Minimal cDC and CD8 T-cell number differences after low-dose MCMV in Dk disparate animals further implied that licensed NK recognition of MCMV imparted qualitative cDC changes to enhance CD8 T-cell priming.

scholarly journals Why Are CD8 T Cell Epitopes of Human Influenza A Virus Conserved?

2019 ◽  
Vol 93 (6) ◽  
Author(s):  
Zheng-Rong Tiger Li ◽  
Veronika I. Zarnitsyna ◽  
Anice C. Lowen ◽  
Daniel Weissman ◽  
Katia Koelle ◽  
...  
Keyword(s):  
T Cell ◽  
Influenza A Virus ◽  
Influenza A ◽  
Cd8 T Cell ◽  
Influenza Vaccines ◽  
T Cell Epitopes ◽  
Class I Mhc ◽  
Mhc I ◽  
Escape Variant ◽  
Wide Range

ABSTRACTThe high degree of conservation of CD8 T cell epitopes of influenza A virus (IAV) may allow for the development of T cell-inducing vaccines that provide protection across different strains and subtypes. This conservation is not fully explained by functional constraint, since an additional mutation(s) can compensate for the replicative fitness loss of IAV escape variants. Here, we propose three additional mechanisms that contribute to the conservation of CD8 T cell epitopes of IAV. First, influenza-specific CD8 T cells may protect predominantly against severe pathology rather than infection and may have only a modest effect on transmission. Second, polymorphism of the human major histocompatibility complex class I (MHC-I) gene restricts the advantage of an escape variant to only a small fraction of the human population who carry the relevant MHC-I alleles. Finally, infection with CD8 T cell escape variants may result in a compensatory increase in the responses to other epitopes of IAV. We use a combination of population genetics and epidemiological models to examine how the interplay between these mechanisms affects the rate of invasion of IAV escape variants. We conclude that for a wide range of biologically reasonable parameters, the invasion of an escape variant virus will be slow, with a timescale of a decade or more. The results suggest T cell-inducing vaccines do not engender the rapid evolution of IAV. Finally, we identify key parameters whose measurement will allow for more accurate quantification of the long-term effectiveness and impact of universal T cell-inducing influenza vaccines.IMPORTANCEUniversal influenza vaccines against the conserved epitopes of influenza A virus have been proposed to minimize the burden of seasonal outbreaks and prepare for the pandemics. However, it is not clear how rapidly T cell-inducing vaccines will select for viruses that escape these T cell responses. Our mathematical models explore the factors that contribute to the conservation of CD8 T cell epitopes and how rapidly the virus will evolve in response to T cell-inducing vaccines. We identify the key biological parameters to be measured and questions that need to be addressed in future studies.

scholarly journals Tumors escape immunosurveillance by overexpressing the proteasome activator REGγ

2019 ◽  
Author(s):  
Mathilde Boulpicante ◽  
Romain Darrigrand ◽  
Alison Pierson ◽  
Valerie Salgues ◽  
Benoit Gaudineau ◽  
...  
Keyword(s):  
T Cell ◽  
Cancer Cells ◽  
Cancer Immunotherapy ◽  
Antigen Processing ◽  
Mrna Translation ◽  
Cd8 T Cell ◽  
Peptide Ligands ◽  
Mhc I ◽  
Peptide Antigens

AbstractThe success of CD8+ T cell based cancer immunotherapy emphasizes the importance of understanding the mechanisms of generation of MHC-I peptide ligands and possible pathways of tumor cell escape from immunosurveillance. Recently, we showed that peptides generated in the nucleus during the pioneer round of mRNA translation (pioneer translation products, or PTPs) can be a potentially important source of tumor specific peptides, given the presence of aberrant splicing and transcription associated with oncogenesis. Here we show that cancer cells up-regulation of the REGγ proteasome regulator results in increased destruction of PTP-derived peptides in the nucleus thus subverting immunosurveillance. These findings add to understanding of the role of REGγ in antigen processing and identify it as a druggable target for improving the efficacy of cancer immunotherapy.SignificanceWith the clear success of CD8+ T cell based immunotherapy, it is critical to understand i) how tumor cells generate MHC-I peptide antigens? and ii) the various mechanisms used by cancer cells to evade immunosurveillance. One of them is to up-regulate the REGγ proteasome regulator which results in an increase destruction of MHC-I peptides in the nucleus thus subverting immunosurveillance.

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