SARS-CoV-2-reactive interferon-γ-producing CD8+ T cells in patients hospitalized with Coronavirus viral disease-2019

There is limited information on SARS-CoV-2 T-cell immune responses in patients with Covid-19. Both CD4+ and CD8+ T cells may be instrumental in the resolution of and protection from SARS-CoV-2 infection. Here, we tested 25 hospitalized patients with either microbiologically documented Covid-19 (n=19) or highly suspected of having the disease (n=6) for the presence of SARS-CoV-2-reactive- CD69+-expressing interferon-gamma;-producing-(IFN-gamma;) CD8+ T cells by a flow-cytometry for intracelular cytokine staining assay. Two sets of overlapping peptides encompassing the SARS-CoV-2 Spike glycoprotein N-terminal 1-643 amino acid sequence and the entire sequence of SARS-CoV-2 M protein were used simultaneously as antigenic stimulus. Ten patients (40%) had detectable responses, displaying frequencies ranging from 0.15 to 2.7% (median of 0.57 cells/microlitre; range, 0.43-9.98 cells/microlitre). The detection rate of SARS-CoV-2-reactive IFN-gamma; CD8+ T cells in patients admitted to intensive care was comparable (P=0.28) to that in patients hospitalized in other medical wards. No correlation was found between SARS-CoV-2-reactive IFN-gamma; CD8+ T-cell counts and SARS-CoV-2 S-specific antibody levels. Likewise, no correlation was observed between either SARS-CoV-2-reactive IFN-gamma; CD8+ T cells or S-specific IgG-antibody titers and blood cell count or levels of inflammatory biomarkers. In summary, in this descriptive, preliminary study we showed that SARS-CoV-2-reactive IFN-gamma; CD8+ T cells can be detected in a non-negligible percentage of patients with moderate to severe forms of Covid-19. Further studies are warranted to determine whether quantitation of these T-cell subsets may provide prognostic information on the clinical course of Covid-19.

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Cortisol and epinephrine control opposing circadian rhythms in T cell subsets

Blood ◽

10.1182/blood-2008-11-190769 ◽

2009 ◽

Vol 113 (21) ◽

pp. 5134-5143 ◽

Cited By ~ 172

Author(s):

Stoyan Dimitrov ◽

Christian Benedict ◽

Dennis Heutling ◽

Jürgen Westermann ◽

Jan Born ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Circadian Rhythms ◽

Cd8 T Cells ◽

Low Dose ◽

Cd8 T Cell ◽

T Cell Subsets ◽

Naive T Cells ◽

Naïve T Cells ◽

Cell Counts

Abstract Pronounced circadian rhythms in numbers of circulating T cells reflect a systemic control of adaptive immunity whose mechanisms are obscure. Here, we show that circadian variations in T cell subpopulations in human blood are differentially regulated via release of cortisol and catecholamines. Within the CD4+ and CD8+ T cell subsets, naive cells show pronounced circadian rhythms with a daytime nadir, whereas (terminally differentiated) effector CD8+ T cell counts peak during daytime. Naive T cells were negatively correlated with cortisol rhythms, decreased after low-dose cortisol infusion, and showed highest expression of CXCR4, which was up-regulated by cortisol. Effector CD8+ T cells were positively correlated with epinephrine rhythms, increased after low-dose epinephrine infusion, and showed highest expression of β-adrenergic and fractalkine receptors (CX3CR1). Daytime increases in cortisol via CXCR4 probably act to redistribute naive T cells to bone marrow, whereas daytime increases in catecholamines via β-adrenoceptors and, possibly, a suppression of fractalkine signaling promote mobilization of effector CD8+ T cells from the marginal pool. Thus, activation of the major stress hormones during daytime favor immediate effector defense but diminish capabilities for initiating adaptive immune responses.

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Prolonged Thrombocytopenia After Allogeneic Hematopoietic Stem Cell Transplantation (allo-HSCT) and Its Association with an Increase in CD8+ CX3CR1+ Cells in Bone Marrow.

Blood ◽

10.1182/blood.v120.21.3077.3077 ◽

2012 ◽

Vol 120 (21) ◽

pp. 3077-3077

Author(s):

Xiao-hui Zhang ◽

Guo-xiang Wang ◽

Yan-rong Liu ◽

Lan-Ping Xu ◽

Kai-Yan Liu ◽

...

Keyword(s):

Bone Marrow ◽

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Surface Expression ◽

T Cell Subsets ◽

Control Group ◽

Hematopoietic Stem ◽

Cell Counts

Abstract Abstract 3077 Background: Since prolonged thrombocytopenia (PT) is an independent risk factor for poor clinical outcome after allogeneic hematopoietic stem cell transplantation (allo-HSCT), the underlying mechanisms need to be understood in order to develop selective treatments. Previous studies1–4 have suggested that abnormalities in B cells may play a role in the pathogenesis of PT. However, abnormalities in B cells alone do not fully explain the complete pathogenic mechanisms of PT. Our previous studies5 showed that the frequency of megakaryocytes with a ploidy value ≤ 8N was significantly increased in patients who developed PT after allo-HSCT compared to the control group. Mechanisms concerning the megakaryocyte hypoplasia in PT after allo-HSCT are not well understood. Design and Methods: PT was defined as a platelet count ≤80 × 109/L for more than 3 months after HSCT, recovery of all other cell counts, and no apparent cause for thrombocytopenia, such as aGVHD, disease recurrence, CMV infection, or antiviral drug treatment at three months post-HSCT when all other blood cell counts had return to normal.5 We analyzed T cell subsets in bone marrow (BM) and peripheral blood (PB) from allo-HSCT recipients with and without PT (n = 23 and 17, respectively) and investigated the expression characteristics of homing receptors CX3CR1, CXCR4 and VLA-4 by flow cytometry. Futhermore, Mononuclear cells (MNCs) from PT patients and controls were cultured with and without autologous CD8+ T cells in vitro, and clarify the effect of activated CD8+ T cells on the ploidy and apoptosis of megakaryocytes in the bone marrow. Results: The results demonstrated that the percentage of CD3+ T cells in the BM was significantly higher in PT patients than the experimental controls (76.00 ± 13.04% and 57.49 ± 9.11%, respectively, P < 0.001), whereas this difference was not significant for the PB (71.01 ± 11.49% and 70.49 ± 12.89%, respectively, P = 0.911). While, some T cell subsets in the BM and PB from allo-HSCT recipients with PT were not significantly different from that of the experimental control group, such as CD8+ T cells, CD4+ T cells, CD4+ CD25bright T cells (regulatory T cells), CD44hi CD62Llo CD8+ T cells and naive T cells (CD11a+ CD45RA+). Furthermore, the surface expression of homing receptor CX3CR1 on BM T cells (64.16 ± 14.07% and 37.45 ± 19.66%, respectively, P < 0.001) and CD8+ T cells (56.25 ± 14.54% and 35.16 ± 20.81%, respectively, P = 0.036), but not in blood, were significantly increased in PT patients compared to controls. For these two groups of patients, the surface expression of CXCR4 and VLA-4 on T cells and CD8+ T cells from both BM and PB did not show significant differences. Through the study in vitro, we found that the activated CD8+ T cells in bone marrow of patients with PT might suppress apoptosis (MNC group and Co-culture group: 18.02 ± 3.60% and 13.39 ± 4.22%, P < 0.05, respectively) and Fas expression (MNC group and Co-culture group: 21.10 ± 3.93 and 15.10 ± 2.33, P <0.05, respectively) of megakaryocyte. In addition, megakaryocyte with a ploidy value ≤ 8N (MNC group: 40.03 ± 6.42% and 24.54 ± 4.31%, respectively, P < 0.05) was significantly increased in patients with PT compared to the control group. Conclusions: In conclusion, an increased surface expression of CX3CR1 on T cells may mediate the recruitment of CD8+ T cells into the bone marrow in patients with PT who received an allo-HSCT. Moreover, CD8+CX3CR1+ T cells, which can have significantly increased numbers in bone marrow of patients with PT, likely caused a reduction in the megakaryocyte ploidy, and suppressed megakaryocyte apoptosis via CD8+ T cell-mediated cytotoxic effect, possibly leading to impaired platelet production. Therefore, treatment targeting CX3CR1 should be considered as a reasonable therapeutic strategy for PT following allo-HSCT. Disclosures: No relevant conflicts of interest to declare.

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Ecto-5′-Nucleotidase (CD73) Regulates the Survival of CD8+ T Cells

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.647058 ◽

2021 ◽

Vol 9 ◽

Author(s):

Mariana V. Rosemblatt ◽

Brian Parra-Tello ◽

Pedro Briceño ◽

Elizabeth Rivas-Yáñez ◽

Suat Tucer ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Interleukin 2 ◽

Cd8 T Cell ◽

Antigenic Stimulation ◽

T Cell Subsets ◽

Limited Information ◽

Α Chain ◽

The Impact

Ecto-5′-nucleotidase (CD73) is an enzyme present on the surface of tumor cells whose primary described function is the production of extracellular adenosine. Due to the immunosuppressive properties of adenosine, CD73 is being investigated as a target for new antitumor therapies. We and others have described that CD73 is present at the surface of different CD8+ T cell subsets. Nonetheless, there is limited information as to whether CD73 affects CD8+ T cell proliferation and survival. In this study, we assessed the impact of CD73 deficiency on CD8+ T cells by analyzing their proliferation and survival in antigenic and homeostatic conditions. Results obtained from adoptive transfer experiments demonstrate a paradoxical role of CD73. On one side, it favors the expression of interleukin-7 receptor α chain on CD8+ T cells and their homeostatic survival; on the other side, it reduces the survival of activated CD8+ T cells under antigenic stimulation. Also, upon in vitro antigenic stimulation, CD73 decreases the expression of interleukin-2 receptor α chain and the anti-apoptotic molecule Bcl-2, findings that may explain the reduced CD8+ T cell survival observed in this condition. These results indicate that CD73 has a dual effect on CD8+ T cells depending on whether they are subject to an antigenic or homeostatic stimulus, and thus, special attention should be given to these aspects when considering CD73 blockade in the design of novel antitumor therapies.

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Robust CD4+ T-cell recovery in adults transplanted with cord blood and no antithymocyte globulin

Blood Advances ◽

10.1182/bloodadvances.2019000836 ◽

2020 ◽

Vol 4 (1) ◽

pp. 191-202 ◽

Cited By ~ 7

Author(s):

Ioannis Politikos ◽

Jessica A. Lavery ◽

Patrick Hilden ◽

Christina Cho ◽

Taylor Borrill ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cord Blood ◽

Cd8 T Cells ◽

Antithymocyte Globulin ◽

Cd8 T Cell ◽

T Cell Subsets ◽

Cd4 T Cell ◽

Cell Recovery ◽

Cell Counts

Abstract Quality of immune reconstitution after cord blood transplantation (CBT) without antithymocyte globulin (ATG) in adults is not established. We analyzed immune recovery in 106 engrafted adult CBT recipients (median age 50 years [range 22-70]) transplanted for hematologic malignancies with cyclosporine/mycophenolate mofetil immunoprophylaxis and no ATG. Patients were treated predominantly for acute leukemia (66%), and almost all (96%) underwent myeloablation. Recovery of CD4+ T cells was faster than CD8+ T cells with median CD4+ T-cell counts exceeding 200/mm3 at 4 months. Early post-CBT, effector memory (EM), and central memory cells were the most common CD4+ subsets, whereas effector and EM were the most common CD8+ T-cell subsets. Naive T-cell subsets increased gradually after 6 to 9 months post-CBT. A higher engrafting CB unit infused viable CD3+ cell dose was associated with improved CD4+ and CD4+CD45RA+ T-cell recovery. Cytomegalovirus reactivation by day 60 was associated with an expansion of total, EM, and effector CD8+ T cells, but lower CD4+ T-cell counts. Acute graft-versus-host disease (aGVHD) did not significantly compromise T-cell reconstitution. In serial landmark analyses, higher CD4+ T-cell counts and phytohemagglutinin responses were associated with reduced overall mortality. In contrast, CD8+ T-cell counts were not significant. Recovery of natural killer and B cells was prompt, reaching medians of 252/mm3 and 150/mm3 by 4 months, respectively, although B-cell recovery was delayed by aGVHD. Neither subset was significantly associated with mortality. ATG-free adult CBT is associated with robust thymus-independent CD4+ T-cell recovery, and CD4+ recovery reduced mortality risk.

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Long-Term Persistence of Functionally Altered GPI-Anchor Negative T-Cell Subsets After Alemtuzumab-Based T-Cell Depleted Hematopoietic Stem Cell Transplantation.

Blood ◽

10.1182/blood.v114.22.2438.2438 ◽

2009 ◽

Vol 114 (22) ◽

pp. 2438-2438

Author(s):

Eva M Wagner ◽

Aline N Lay ◽

Timo Schmitt ◽

Julia Hemmerling ◽

Diana Wolff ◽

...

Keyword(s):

T Cells ◽

Stem Cell ◽

T Cell ◽

Hematopoietic Stem Cell Transplantation ◽

Cd8 T Cells ◽

T Cell Subsets ◽

Gpi Anchor ◽

Ifn Gamma ◽

Hematopoietic Stem

Abstract Abstract 2438 Poster Board II-415 The anti CD52 antibody alemtuzumab is frequently used for in vivo T cell depletion (TCD) in the context of allogeneic hematopoietic stem cell transplantation (HSCT). We have recently demonstrated the persistence of CD52-negative T-cell subsets in patients after HSCT following alemtuzumab-mediated TCD (Meyer, Wagner et al., Bone Marrow Transplantation 2009). The loss of CD52 among lymphocytes was exclusively related to T cells and was more prominent in CD4 compared to CD8 T cells. CD8-depleted donor-lymphocyte infusions (DLI) increased the percentage of CD52-positive CD4 T cells. In patients who did not receive DLI, CD52-negative T cells were detected in significant proportions of up to 40% found even more than 3 years after transplantation. We therefore investigated the regulation as well as the functional consequences of a loss of CD52-expression in T cells of our patients. Peripheral blood T cells of patients with CD52-negative T cells after more than 12 months post allogeneic HSCT following TCD with high-dose alemtuzumab (100 mg) were sorted according to their expression of CD52. RT-PCR showed no difference in CD52 mRNA expression of CD52-positive compared to negative T cells. Since transcriptional regulation was therefore unlikely and CD52 is a glycosylphosphatidylinositol (GPI)-anchored protein, we stained for the presence of further GPI-anchored molecules such as CD55 and CD59 on peripheral blood lymphocytes of our patients. We found that the CD52-negative T cells had also lost expression of CD55 and CD59, whereas CD52-positive cells remained positive for these antigens. We then directly labeled the GPI-anchors using FLAER (fluorescent aerolysin) and thereby confirmed that the loss of CD52 was correlated with a reduced density of the GPI-anchors in the cell-membrane. However, our patients did not exhibit clinical signs of paroxysmal nocturnal hemoglobinuria (PNH), which is in line with the finding that the loss of GPI-anchors was only related to T cells. With the aim to characterize the functional impact of the reduced GPI-anchor density on T cells, we separated CD52-negative from CD52-positive T cells by flow cytometry. The subpopulations were expanded in vitro using low-dose IL2, OKT3, and allogeneic feeder-cells. CD52 expression remained unaltered in CD52-negative as well as CD52-positive cultures for more than 6 weeks. In contrast, when purified T cells of healthy donors were treated with alemtuzumab in vitro (10 μg/mL, 4 h), we only observed a transient down-regulation of the antigen. The growth-kinetics of the non-specifically stimulated T cell cultures did not differ between the CD52-positive and the negative cultures. Yet, when we expanded T cells of a cytomegalovirus (CMV)-positive patient, transplanted from a CMV-positive donor, by subsequent stimulation with overlapping peptides of CMV-pp65, only the proliferation of CD52-positive T cells increased after the addition of peptides. We furthermore applied CD52-positive as well as CD52-negative CD4 and CD8 T cells derived from the antigen-independent culture of this patient in an IFN-gamma ELISPOT assay with autologous dendritic cells (DC) loaded with overlapping peptides of CMV-pp65 and IE1. CMV-specific IFN-gamma spot-production was only evident in the CD52-positive populations. We also conducted IFN-gamma secretion-assays on ex vivo T cells stimulated with autologous DC loaded with CMV-peptides and found a reduced antigen-specific IFN-gamma production in CD52-negative CD4 and CD8 T cells. In addition, we analyzed IFN-gamma secretion of T cells following allogeneic stimulation with DC of a healthy individual and again detected lower levels of IFN-gamma production by CD52-negative compared to CD52-positive T cells. In summary, we demonstrated that the permanent loss of CD52 in a proportion of reconstituting T cells after alemtzumab-based TCD is associated with a loss of GPI-anchors in the cellular membrane. Our data suggest that this loss correlates with reduced T-cell effector-functions in response to antigen-specific stimulation. In addition to a better understanding of the role of alemtuzumab-mediated TCD on T cell reconstitution, further comparison of functional responses in different T-cell subsets in association with the presence or absence of GPI-anchors might help to explore the impact of GPI-anchors and GPI-anchored molecules in this context. Disclosures: No relevant conflicts of interest to declare.

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Alterations in regulatory T cells and immune checkpoint molecules in pancreatic cancer patients receiving FOLFIRINOX or gemcitabine plus nab-paclitaxel

Clinical & Translational Oncology ◽

10.1007/s12094-021-02620-x ◽

2021 ◽

Author(s):

L. Sams ◽

S. Kruger ◽

V. Heinemann ◽

D. Bararia ◽

S. Haebe ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Regulatory T Cells ◽

Cd8 T Cells ◽

Mononuclear Cells ◽

Progression Free Survival ◽

Ductal Adenocarcinoma ◽

Immune Checkpoints ◽

Prognostic Information ◽

Peripheral Blood Mononuclear

Abstract Purpose This pilot study aimed on generating insight on alterations in circulating immune cells during the use of FOLFIRINOX and gemcitabine/nab-paclitaxel in pancreatic ductal adenocarcinoma (PDAC). Patients and methods Peripheral blood mononuclear cells were isolated before and 30 days after initiation of chemotherapy from 20 patients with advanced PDAC. Regulatory T cells (FoxP3+) and immune checkpoints (PD-1 and TIM-3) were analyzed by flow cytometry and immunological changes were correlated with clinical outcome. Results Heterogeneous changes during chemotherapy were observed in circulating T-cell subpopulations with a pronounced effect on PD-1+ CD4+/CD8+ T cells. An increase in FoxP3+ or PD-1+ T cells had no significant effect on survival. An increase in TIM3+/CD8+ (but not TIM3+/CD4+) T cells was associated with a significant inferior outcome: median progression-free survival in the subgroup with an increase of TIM-3+/CD8+ T cells was 6.0 compared to 14.0 months in patients with a decrease/no change (p = 0.026); corresponding median overall survival was 13.0 and 20.0 months (p = 0.011), respectively. Conclusions Chemotherapy with FOLFIRNOX or gemcitabine/nab-paclitaxel induces variable changes in circulating T-cell populations that may provide prognostic information in PDAC.

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549 Characterizing double positive T cells in the tumor microenvironment: a tale of promiscuous cell fates

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-sitc2020.0549 ◽

2020 ◽

Vol 8 (Suppl 3) ◽

pp. A586-A586

Author(s):

Sara Schad ◽

Andrew Chow ◽

Heng Pan ◽

Levi Mangarin ◽

Roberta Zappasodi ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Tumor Microenvironment ◽

Cd8 T Cells ◽

Human Melanoma ◽

B16 Melanoma ◽

T Cell Subsets ◽

Double Positive ◽

Cell Fates ◽

Single Positive

BackgroundCD4 and CD8 T cells are genetically and functionally distinct cell subsets of the adaptive immune system that play pivotal roles in immune surveillance and disease control. During development in the thymus, transcription factors ThPOK and Runx3 regulate the differentiation and maturation of these two lineages into single positive T cells that enter the periphery with mutually exclusive expression of either the CD4 or CD8 co-receptor.1–2 Despite our expectation that these two cell fates are fixed, mature CD4+CD8+ double positive (DP) T cells have been described in the context of numerous immunological responses, including cancer, but their molecular and functional properties and therapeutic relevance remain controversial and largely unknown.3–5MethodsOur lab has identified and characterized a heterogenous DP T cell population in murine and human melanoma tumors comprised of CD4 and CD8 T cells re-expressing the opposite co-receptor and a parallel uptake in the opposite cell type’s phenotype and function. Using CD4 (Trp1) and CD8 (Pmel) transgenic TCR T cells specific to B16 melanoma antigens gp75 and gp100 respectively, we demonstrate the re-expression of the opposite co-receptor following adoptive T cell transfer in B16 melanoma tumor bearing mice.ResultsSpecifically, up to 50% of transferred CD4 Trp1 T cells will re-express CD8 to become a DP T cell in the tumor microenvironment. Further, these CD4 derived DP T cells upregulate CD8 lineage regulator Runx3 and cytolytic genes Gzmb, Gzmk, and Prf1 to become potent cytotoxic T cells. Alternatively, a subset of CD8 Pmel T cells differentiate into DP T cells characterized by the increased expression of CD4, ThPOK, and regulatory marker FoxP3 (figure 1). In addition, we utilized 10x single cell and ATAC sequencing to further characterize these divergent DP T cell populations among open repertoire T cells isolated from murine and human melanoma tumors.ConclusionsOur findings highlight the capability of single positive T cells to differentiate in response to antigen and local stimuli into novel T cell subsets with polyfunctional characteristics. The resulting cell subsets will potentially affect the tumor microenvironment in distinct ways. Our studies may inform therapeutic approaches to identify antigen specific T cells as well as innovative signaling pathways to target when genetically engineering T cells to optimize cytotoxic function in the setting of adoptive cell therapy.Ethics ApprovalThe human biospecimen analyses were approved by Memorial Sloan Kettering Cancer Center IRB #06-107ReferencesEllmeier W, Haust L & Tschismarov R. Transcriptional control of CD4 and CD8 coreceptor expression during T cell development. Cell Mol Life Sci 2013;70:4537–4553.Luckey MA, et al. The transcription factor ThPOK suppresses Runx3 and imposes CD4+ lineage fate by inducing the SOCS suppressors of cytokine signaling. Nature Immunology 2014; 15, 638–645.Bohner P, et al. Double positive CD4(+)CD8(+) T Cells are enriched in urological cancers and favor T Helper-2 polarization. Front Immunol 2019; 10, 622.Nascimbeni M, Shin E-C, Chiriboga L, Kleiner DE & Rehermann B. Peripheral CD4(+)CD8(+) T cells are differentiated effector memory cells with antiviral functions. Blood 2004;104:478–486.Nishida K, et al. Clinical importance of the expression of CD4+CD8+ T cells in renal cell carcinoma. Int Immunol 2020;32:347–357.

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Long-Term Depletion of Naive T Cells in Patients Treated for Hodgkin's Disease

Blood ◽

10.1182/blood.v90.9.3662 ◽

1997 ◽

Vol 90 (9) ◽

pp. 3662-3672 ◽

Cited By ~ 49

Author(s):

Nobukazu Watanabe ◽

Stephen C. De Rosa ◽

Anthony Cmelak ◽

Richard Hoppe ◽

Leonore A. Herzenberg ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Hodgkin's Disease ◽

Hodgkin’S Disease ◽

Cell Subset ◽

T Cell Subsets ◽

Naive T Cells ◽

Naïve T Cells ◽

Cell Counts

Abstract We investigated the representation of T cells in patients who had been treated for Hodgkin's disease (HD). We found a marked depletion in both CD4 and CD8 naive T-cell counts that persists up to 30 years after completion of treatment. In contrast, CD4 and CD8 memory T-cell subsets recovered to normal or above normal levels by 5 years posttreatment. Thus, the previously-reported long-term deficit in total CD4 T-cell counts after treatment for HD is due to specific depletion of naive T cells. Similarly, total CD8 T-cell counts return to normal by 5 years only because CD8 memory T cells expand to higher than normal levels. These findings suggest that the treatment (mediastinal irradiation) results in a longterm dysregulation of T-cell subset homeostasis. The profound depletion of naive T cells may explain the altered T-cell function in treated patients, including the poor response to immunization after treatment for HD. Further, in some individuals, we identified expansions of unusual subsets expressing low levels of CD8. Eight-color fluorescence-activated cell sorting analyses showed that these cells largely express CD8αα homodimers and CD57, consistent with the phenotype of potentially extrathymically derived T cells. In addition, these cells, both CD4+ and CD4−, are probably cytotoxic lymphocytes, as they express high levels of intracellular perforin. In adults treated for HD, an increased activity of extrathymic T-cell differentiation may partially compensate for the loss of thymic-derived T cells.

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644 Tumor-mediated suppressive signaling and hypoxia supports altered chromatin landscapes that limit the transcriptional and functional potential of terminal T cell exhaustion

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2021-sitc2021.644 ◽

2021 ◽

Vol 9 (Suppl 3) ◽

pp. A673-A673

Author(s):

Rhodes Ford ◽

Natalie Rittenhouse ◽

Nicole Scharping ◽

Paolo Vignali ◽

Greg Delgoffe ◽

...

Keyword(s):

Gene Expression ◽

T Cells ◽

T Cell ◽

Tumor Microenvironment ◽

Histone Modifications ◽

Cd8 T Cells ◽

Tumor Hypoxia ◽

T Cell Subsets ◽

T Cell Exhaustion ◽

Cell Exhaustion

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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Mitochondrial Dysfunction Associates With Acute T Lymphocytopenia and Impaired Functionality in COVID-19 Patients

Frontiers in Immunology ◽

10.3389/fimmu.2021.799896 ◽

2022 ◽

Vol 12 ◽

Author(s):

Yufei Mo ◽

Kelvin Kai-Wang To ◽

Runhong Zhou ◽

Li Liu ◽

Tianyu Cao ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Mitochondrial Dysfunction ◽

Cd8 T Cells ◽

Functional Impairment ◽

Cell Loss ◽

Cd8 T Cell ◽

Underlying Mechanism ◽

T Cell Subsets ◽

Effector Memory

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection results in rapid T lymphocytopenia and functional impairment of T cells. The underlying mechanism, however, remains incompletely understood. In this study, we focused on characterizing the phenotype and kinetics of T-cell subsets with mitochondrial dysfunction (MD) by multicolor flow cytometry and investigating the association between MD and T-cell functionality. While 73.9% of study subjects displayed clinical lymphocytopenia upon hospital admission, a significant reduction of CD4 or CD8 T-cell frequency was found in all asymptomatic, symptomatic, and convalescent cases. CD4 and CD8 T cells with increased MD were found in both asymptomatic and symptomatic patients within the first week of symptom onset. Lower proportion of memory CD8 T cell with MD was found in severe patients than in mild ones at the stage of disease progression. Critically, the frequency of T cells with MD in symptomatic patients was preferentially associated with CD4 T-cell loss and CD8 T-cell hyperactivation, respectively. Patients bearing effector memory CD4 and CD8 T cells with the phenotype of high MD exhibited poorer T-cell responses upon either phorbol 12-myristate-13-acetate (PMA)/ionomycin or SARS-CoV-2 peptide stimulation than those with low MD. Our findings demonstrated an MD-associated mechanism underlying SARS-CoV-2-induced T lymphocytopenia and functional impairment during the acute phase of infection.

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