Blocking VIP Signaling Abrogates Upregulation Of PD1 and Increases Proliferation Of Allo-Reactive T-Cells In a Mixed Lymphocyte Reaction

Abstract Introduction Vasoactive intestinal peptide (VIP) is a neuropeptide hormone that suppresses Th1 immunity and inhibits antiviral immunity. Decreased Th1 immunity is problematic for allogeneic bone marrow transplant (allo-BMT) patients requiring T-cell immunity against blood cancers (Graft-versus-Tumor) and against secondary infections such as CMV. VIPhyb, a modified VIP peptide, is a VIP receptor antagonist that decreases VIP signaling. VIP-knockout mice and mice treated with VIPhyb after allo-BMT are known to have better antiviral immunity and survival after CMV infection without increasing GvHD (Li et al. PLoS One. 2013 May 27;8(5):e63381) (Li et al. Blood. 2013 Mar 21;121(12):2347-51.), thus making VIPhyb of interest for pharmacological use in humans to improve the efficacy of allo-BMT The effects of VIPhyb on T-cell immunity are not yet fully profiled. This study aimed to analyze the effects of VIPhyb on CD4+ and CD8+ T-cell proliferation and activation in order to better understand the mechanistic implications of VIP inhibition on T-cell adaptive immunity. This study also aimed to show that mixed lymphocyte reactions (MLRs), an in vitro allo-BMT model, could be used to provide rapid and reliable results that are consistent with in vivo data. It was hypothesized that VIPhyb would increase T-cell immunity as profiled by: increased T-cell proliferation, CD69 and PD1 co-upregulation in early T-cell activation, and PD1 downregulation in T-cells after initial activation. Methods Splenocytes from two histoincompatible mice were cultured together at 37°C in a 1:1 ratio in a one-way MLR. BALB/c splenocytes (stimulators) were irradiated at 20Gy, and Pepboy splenocytes (responders) were labeled with CFSE to trace proliferation. VIPhyb was added daily to the cell cultures in doses of 0.1μM, 0.3μM, 1μM, or 3μM. Treatment groups were compared to a PBS control. Proliferation, CD69, and PD1 were assessed by flow cytometry on the BD FACSAria. All results are shown as mean ± SEM (n=3). One-way ANOVA tests with Dunnett post-tests were calculated using Prism software. *p < 0.05; **p < 0.01; ***p < 0.001 Results VIPhyb increased CD4+ and CD8+ T-cell proliferation: 3, 5, and 7 days after initiating a one-way MLR, CFSE expression of Pepboy responder T-cells was assessed using flow cytometry (Figure 1). As the VIPhyb dose increased, the percentage of initial splenocytes that underwent proliferation increased in both CD4+ and CD8+ T-cells. VIPhyb increased early T-cell CD69 expression and abrogated later PD1 upregulation in CD8+ T-cells: 3, 5, and 7 days after initiating a one-way MLR, expression levels of CD69 and PD1 on Pepboy responder T-cells were assessed by flow cytometry. Significant upregulation of CD69 on CD4+ and CD8+ T-cells on day 3 occurred with increasing VIPhyb doses (Figures 2A and 2B). PD1 was co-upregulated with CD69 during early activation, and VIPhyb significantly decreased PD1 expression on CD8+ T-cells on days 5 and 7 (Figures 2C and 2D). Conclusions VIPhyb increased T-cell proliferation; CD8+ T-cells were affected more significantly. VIPhyb increased early co-upregulation of CD69 and PD1 in all T-cells and significantly decreased later CD8+ T-cell PD1 expression, indicating that VIPhyb increases T-cell activation. We hypothesize that the decreased PD1 expression will be critical for understanding the pathways involved in VIP inhibition. Importantly, since it has been shown in vivo that VIPhyb does not increase GvHD, then it can be assumed that the VIPhyb-induced T-cell proliferation and activation will increase GvL and adaptive immunity without increasing alloreactivity. Notably, these results are consistent with published in vivo data, which demonstrates that the MLR can be used as a faster method of analyzing pharmacological compounds than in vivo experiments. Given these results, VIPhyb is still of interest as a potential therapy for allo-BMT patients. Disclosures: No relevant conflicts of interest to declare.

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Proliferation of CD8+ T-Cells Specific for CMV and EBV in Response to TCR Mediated Recognition of Cognate Antigen Is Inhibited by Imatinib in a Dose-Dependent Manner.

Blood ◽

10.1182/blood.v104.11.1342.1342 ◽

2004 ◽

Vol 104 (11) ◽

pp. 1342-1342

Author(s):

Ruth Seggewiss ◽

Karin Lore ◽

Elisabeth Greiner ◽

Magnus K. Magnusson ◽

David A. Price ◽

...

Keyword(s):

Cell Proliferation ◽

T Cells ◽

T Cell ◽

Tyrosine Kinase ◽

Cd8 T Cells ◽

Cd8 T Cell ◽

T Cell Proliferation ◽

Cell Transplant ◽

Dose Dependent

Abstract We and others have shown that the tyrosine kinase inhibitor imatinib (STI571, Gleevec®) inhibits T-cell proliferation and activation at concentrations achieved in vivo. At 10μM, imatinib inhibited T-cell receptor (TCR)-mediated proliferation of purified peripheral blood T-cells almost completely. Up-regulation of the activation markers CD25 and CD69 at 24h in response to TCR cross-linking was suppressed by imatinib at a mean IC50 of 5.4μM and 7.3μM, respectively and IL-2 production was also severely impaired. However, these assays may not fully reflect the response to clinical relevant antigens. Therefore, we chose to investigate the antigen-triggered proliferation of memory CD8+ T-cells specific for immunodominant CMV and EBV HLA-A2 peptide epitopes. We used HLA-peptide tetramers to identify healthy blood donors with detectable CMV- or EBV-specific CD8+ T-cell populations. Purified T-cells from these donors were then stimulated with the CMV peptide pp65495–503 or the EBV peptide BMFLI259–267. Antigen-induced proliferation was measured by dilution of the vital dye CFSE over a period of 4 or 8 days. The magnitude of the virusspecific CD8+ T-cell population ranged from 0.5 % to 7.1% of CD8+ T-cells for CMV and from 0.05% to 0.35% of CD8+ T-cells for EBV. Antigen-specific CD8+ T-cells from all 10 donors studied proliferated in response to the CMV peptide. In 8 from 10 donors, imatinib reduced CMV peptide induced proliferation. With increasing imatinib concentrations (range: 5 – 10μM), we observed dose dependent reduction of both the number of cells undergoing cell division and the average number of divisions completed per cell. Comparable inhibition of specific T-cell proliferation in response to the EBV-derived peptide was observed in two donors. Immunoblots demonstrated that imatinib substantially reduced tyrosine phosphorylation of ZAP70 and LAT in response to TCR-mediated activation in Jurkat T-cells. Sequence comparisons of all 90 tyrosine kinase genes in the human genome for homology in the ATP binding pocket identified Lck, which is required for ZAP70 activation, as a likely target for imatinib. Our results indicate that imatinib may interfere with clinically important T-cell effector functions. As concentrations sufficient for half-maximal inhibition of TCR signalling are achieved in vivo, imatinib could increase the risk of opportunistic infections and impact on GVH and GVL reactions post-transplantation especially when used in conjuction with other immunosuppressive agents. Therefore, close monitoring of patients on imatinib for CMV reactivation or EBV-induced lymphoproliferative diseases, especially in stem cell transplant recipients, appears warranted.

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Naive CD8+ T cells differentiate into protective memory-like cells after IL-2–anti–IL-2 complex treatment in vivo

Journal of Experimental Medicine ◽

10.1084/jem.20070543 ◽

2007 ◽

Vol 204 (8) ◽

pp. 1803-1812 ◽

Cited By ~ 76

Author(s):

Daisuke Kamimura ◽

Michael J. Bevan

Keyword(s):

Cell Proliferation ◽

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Cd8 T Cell ◽

T Cell Response ◽

T Cell Proliferation ◽

Memory Phenotype

An optimal CD8+ T cell response requires signals from the T cell receptor (TCR), co-stimulatory molecules, and cytokines. In most cases, the relative contribution of these signals to CD8+ T cell proliferation, accumulation, effector function, and differentiation to memory is unknown. Recent work (Boyman, O., M. Kovar, M.P. Rubinstein, C.D. Surh, and J. Sprent. 2006. Science. 311:1924–1927; Kamimura, D., Y. Sawa, M. Sato, E. Agung, T. Hirano, and M. Murakami. 2006. J. Immunol. 177:306–314) has shown that anti–interleukin (IL) 2 monoclonal antibodies that are neutralizing in vitro enhance the potency of IL-2 in vivo. We investigated the role of IL-2 signals in driving CD8+ T cell proliferation in the absence of TCR stimulation by foreign antigen. IL-2 signals induced rapid activation of signal transducer and activator of transcription 5 in all CD8+ T cells, both naive and memory phenotype, and promoted the differentiation of naive CD8+ T cells into effector cells. IL-2–anti–IL-2 complexes induced proliferation of naive CD8+ T cells in an environment with limited access to self–major histocompatibility complex (MHC) and when competition for self-MHC ligands was severe. After transfer into wild-type animals, IL-2–activated CD8+ T cells attained and maintained a central memory phenotype and protected against lethal bacterial infection. IL-2–anti–IL-2 complex–driven memory-like CD8+ T cells had incomplete cellular fitness compared with antigen-driven memory cells regarding homeostatic turnover and cytokine production. These results suggest that intense IL-2 signals, with limited contribution from the TCR, program the differentiation of protective memory-like CD8+ cells but are insufficient to guarantee overall cellular fitness.

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DC-Based Vaccines for Cancer Immunotherapy

Vaccines ◽

10.3390/vaccines8040706 ◽

2020 ◽

Vol 8 (4) ◽

pp. 706

Author(s):

Chunmei Fu ◽

Li Zhou ◽

Qing-Sheng Mi ◽

Aimin Jiang

Keyword(s):

Clinical Trials ◽

T Cells ◽

Dendritic Cells ◽

T Cell ◽

Cd8 T Cells ◽

Critical Role ◽

Cd8 T Cell ◽

T Cell Immunity ◽

Cell Responses ◽

Cell Immunity

As the sentinels of the immune system, dendritic cells (DCs) play a critical role in initiating and regulating antigen-specific immune responses. Cross-priming, a process that DCs activate CD8 T cells by cross-presenting exogenous antigens onto their MHCI (Major Histocompatibility Complex class I), plays a critical role in mediating CD8 T cell immunity as well as tolerance. Current DC vaccines have remained largely unsuccessful despite their ability to potentiate both effector and memory CD8 T cell responses. There are two major hurdles for the success of DC-based vaccines: tumor-mediated immunosuppression and the functional limitation of the commonly used monocyte-derived dendritic cells (MoDCs). Due to their resistance to tumor-mediated suppression as inert vesicles, DC-derived exosomes (DCexos) have garnered much interest as cell-free therapeutic agents. However, current DCexo clinical trials have shown limited clinical benefits and failed to generate antigen-specific T cell responses. Another exciting development is the use of naturally circulating DCs instead of in vitro cultured DCs, as clinical trials with both human blood cDC2s (type 2 conventional DCs) and plasmacytoid DCs (pDCs) have shown promising results. pDC vaccines were particularly encouraging, especially in light of promising data from a recent clinical trial using a human pDC cell line, despite pDCs being considered tolerogenic and playing a suppressive role in tumors. However, how pDCs generate anti-tumor CD8 T cell immunity remains poorly understood, thus hindering their clinical advance. Using a pDC-targeted vaccine model, we have recently reported that while pDC-targeted vaccines led to strong cross-priming and durable CD8 T cell immunity, cross-presenting pDCs required cDCs to achieve cross-priming in vivo by transferring antigens to cDCs. Antigen transfer from pDCs to bystander cDCs was mediated by pDC-derived exosomes (pDCexos), which similarly required cDCs for cross-priming of antigen-specific CD8 T cells. pDCexos thus represent a new addition in our arsenal of DC-based cancer vaccines that would potentially combine the advantage of pDCs and DCexos.

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EXTH-51. GENETICALLY STABLE POLIOVIRUS VECTOR PLATFORM FOR DIPG IMMUNOTHERAPY

Neuro-Oncology ◽

10.1093/neuonc/noz175.382 ◽

2019 ◽

Vol 21 (Supplement_6) ◽

pp. vi93-vi93

Author(s):

Matthias Gromeier ◽

Mubeen Mosaheb ◽

Elena Dobrikova ◽

Michael Brown ◽

Darell Bigner ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Viral Vector ◽

T Cell Responses ◽

Cd8 T Cell ◽

Anatomical Location ◽

Cell Responses ◽

Cell Immunity

Abstract Options for the immunotherapy of diffuse intrinsic pontine glioma (DIPG), due to its anatomical location and inherent therapy resistance, are limited. The histone 3.3(K27M) mutation in ~80% of such tumors offers a unique opportunity for immunotherapy intervention, as it defines a high affinity, HLA-A2-restricted tumor neoantigen that spontaneously elicits CD8+ T cell responses in DIPG patients. Immunizing against the H3.3(K27M) signature in the clinic has been challenging, as conventional approaches (i.e. peptide-conjugates administered with adjuvants) lack the costimulatory signals known to drive CD8+ effector T cell responses. Therefore, we built on a viral vector approach for engaging innate immune responses to virus infection specifically in antigen presenting cells. Viruses naturally engage innate immunity, induce antigen presentation, and mediate CD8 T cell priming against foreign antigens. Polioviruses can provide a context optimal for generating antigen-specific CD8 T cells, as they have natural tropism for dendritic cells, preeminent inducers of CD8 T cell immunity; elicit Th1-promoting inflammation; and lack interference with innate or adaptive immunity. However, notorious genetic instability and underlying neuropathogenicity has hampered poliovirus-based vector applications. We devised a strategy based on the polio:rhinovirus chimera PVSRIPO, devoid of viral neuropathogenicity after intracerebral inoculation in human subjects, for stable expression of exogenous antigens. PVSRIPO vectors infect, activate, and induce epitope presentation in DCs in vitro; recruit and activate DCs with Th1-dominant cytokine profiles at the injection site in vivo. They efficiently prime tumor antigen-specific CD8 T cells in vivo, induce CD8 T cell migration to the tumor site, delay tumor growth and enhance survival in syngeneic rodent tumor models. We are preparing a prototype PVSRIPO-derived vector delivering the H3.3(K27M) signature for clinical investigation.

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Microrna-17-92 Cluster: Novel Target for Controlling Gvhd While Preserving GVL Effect

Blood ◽

10.1182/blood.v124.21.845.845 ◽

2014 ◽

Vol 124 (21) ◽

pp. 845-845

Author(s):

Yongxia Wu ◽

David Bastian ◽

Jessica Lauren Heinrichs ◽

Jianing Fu ◽

Hung Nguyen ◽

...

Keyword(s):

Cell Proliferation ◽

T Cells ◽

Cell Death ◽

T Cell ◽

Cd8 T Cells ◽

Locked Nucleic Acid ◽

T Cell Proliferation ◽

Allogeneic Bone

Abstract Graft-versus-host disease (GVHD) remains a life threatening complication after allogeneic hematopoietic stem cell transplantation (HCT). Donor T cells are the key pathogenic effectors in the induction of GVHD. MicroRNAs (miRs) have been shown to play an important role in orchestrating immune response, among which miR-17-92 cluster is one of the best characterized miR clusters that encodes 6 miRs including 17, 18a, 19a, 20a, 19b-1 and 92-1. Although regulatory functions of miR-17-92 cluster have been elaborated in a variety of immune responses including anti-infection, anti-tumor, and autoimmunity, the role of this miR cluster in the modulation of T-cell response to alloantigens and the development of GVHD has not been explored previously. Based on the previous report that miR-17-92 promotes Th1 responses and inhibits induced regulatory T-cell (iTreg) differentiation in vitro, we hypothesized that blockade of miR-17-92 would constrain T-cell alloresponse and attenuate GVHD. To evaluate the function of miR-17-92 on T-cell alloresponse, we utilized the mice with miR-17-92 conditional knock-out (KO) on T cells as donors, and compared the alloresponse of WT and KO T cells after allogeneic bone marrow transplantation (allo-BMT). We observed that KO T cells had substantially reduced ability to proliferate and produce IFNγ as compared to WT counterparts 4 days after cell transfer. Interestingly, CD4 but not CD8 KO T cells had increased cell death in the population of fast-dividing T cells. Thus, miR-17-92 cluster promotes activation and expansion of both CD4 and CD8 T cells, and inhibits activation-induced cell death of CD4 but not CD8 T cells at the early stage of alloresponse in vivo. We further evaluated the role of miR-17-92 on T cells in the development of acute GVHD in a fully MHC-mismatched BMT model. In sharp contrast to WT T cells that caused severe GVHD and resulted in 100% mortality of the recipients, KO T cells were impaired in causing severe GVHD reflected by mild clinical manifestations and no mortality. These observations were extended to MHC-matched but minor antigen-mismatched as well as haploidentical BMT models that are more clinically relevant. We next addressed the critical question whether T cells deficient for miR-17-92 are still capable of mediating graft-versus-leukemia (GVL) effect. Using A20 lymphoma and P815 mastocytoma cell lines, we demonstrated that the KO T cells essentially retained the GVL activity in MHC-mismatched and haploidentical BMT model, respectively. Mechanistic studies revealed that miR-17-92 promoted CD4 T-cell proliferation, survival, migration to target organs, and Th1-differentiation, but reduced Th2-differentiation and iTreg generation. However, miR-17-92 had less impact on CD8 T-cell proliferation, survival, IFNγ production, and cytolytic activity reflected by granzyme B and CD107a expression. Moreover, miR-17-92 negatively regulated TNFα production by both CD4 and CD8 T cells. We therefore conclude that miR-17-92 cluster is required for T cells to induce severe GVHD, but it is dispensable for T cells to mediate the GVL effect. To increase translational potential of our findings, we designed the locked nucleic acid (LNA) antagomirs specific for miR-17 or miR-19, which have been reported to be the key members in this cluster. We observed that the treatment with anti-miR-17 significantly inhibited T-cell expansion and IFNγ production in response to alloantigen in vivo, and anti-miR-19 was more effective. Furthermore, our ongoing experiment showed the treatment with anti-miR-17 or anti-miR-19 was able to considerably attenuate the severity of GVHD as compared to scrambled antagomir in a MHC-mismatched BMT model. Taken together, the current work reveals that miR-17-92 cluster is essential for T-cell alloresponse and GVHD development, and validates miR-17-92 cluster as promising therapeutic target for the control of GVHD while preserving GVL activity in allogeneic HCT. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

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Gag-Specific CD8 T-Cell Proliferation Is Associated With Higher Peripheral Blood Levels of Transforming Growth Factor-β and Gut-Homing T Cells in Youths Perinatally Infected With Human Immunodeficiency Virus-1: The ANRS-EP38-IMMIP Study

Open Forum Infectious Diseases ◽

10.1093/ofid/ofw239 ◽

2016 ◽

Vol 4 (1) ◽

Author(s):

Josiane Warszawski ◽

Véronique Avettand-Fenoel ◽

Christine Rouzioux ◽

Daniel Scott-Algara ◽

Thomas Montange ◽

...

Keyword(s):

Flow Cytometry ◽

Human Immunodeficiency Virus ◽

Cell Proliferation ◽

T Cells ◽

T Cell ◽

Transforming Growth Factor ◽

Cd8 T Cell ◽

T Cell Proliferation ◽

Immunodeficiency Virus ◽

Tgf Β1

Abstract Background Gag-specific T lymphocytes play a key role in the control of human immunodeficiency virus (HIV) replication. Their restoration will be important for future reservoir targeting strategies. In this study, we aimed to identify immune correlates of Gag-specific CD8 T-cell proliferation in youths with perinatally acquired HIV-1 infection. Methods The ANRS-EP38-IMMIP study included youths of 15 to 24 years of age. Fifty-three were taking combination anti-retroviral therapy and aviremic at the time of the study and had undergone valid 5-6-carboxyfluorescein diacetate succimidyl ester-based flow cytometry T-cell proliferation assays. Plasma analytes were quantified by enzyme-linked immunosorbent assay or multiplex assays. Peripheral blood cells were phenotyped by flow cytometry. Logistic regression was used to study the association between Gag-specific T-cell proliferation and immune markers. Results Patients with Gag-specific CD8 T-cell proliferation had higher levels of plasma transforming growth factor (TGF)-β1, a lower proportion of naive cells among regulatory T cells (Tregs), and higher percentages of CD4 and CD8 T cells expressing the α4β7 integrin or CD161 molecule than those without a Gag-specific response. These associations were significant based on analyses including potential confounders. Conclusions Preserved Gag-specific CD8 T-cell proliferation was associated with higher TGF-β1 levels and increased percentages of T cells with a gut-homing phenotype at least 15 years after HIV infection during the perinatal period.

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Transregulation of memory CD8 T-cell proliferation by IL-15Rα+ bone marrow–derived cells

Blood ◽

10.1182/blood-2003-08-2814 ◽

2004 ◽

Vol 103 (3) ◽

pp. 988-994 ◽

Cited By ~ 119

Author(s):

Kimberly S. Schluns ◽

Kimberly D. Klonowski ◽

Leo Lefrançois

Keyword(s):

Bone Marrow ◽

Cell Proliferation ◽

T Cells ◽

Cell Division ◽

T Cell ◽

Cd8 T Cells ◽

Cd8 T Cell ◽

T Cell Proliferation ◽

Memory Cd8 T Cells ◽

Basal Proliferation

AbstractInterleukin 15 (IL-15) and the IL-15 receptor α (IL-15Rα) chain are both required for the basal proliferation of memory CD8 T cells, but which cell types are required to express IL-15 or IL-15Rα to mediate this proliferation is not known. Using bone marrow (BM) chimeras, we showed that virus-specific CD8 memory T-cell proliferation was driven by IL-15 produced by either BM-derived or parenchymal cells. Experiments using mixed BM chimeras showed that IL-15Rα expression by memory CD8 T cells was not required for their division. In addition, wild-type memory CD8 T cells did not divide after transfer into IL-15Rα-/- mice. Further analyses demonstrated that IL-15Rα+ BM-derived cells were crucial in driving memory CD8 T-cell division in the spleen while both parenchymal and BM-derived cells promoted memory cell division in the lung. Proliferation in response to soluble IL-15 in vivo required expression of IL-15Rα by opposing cells and IL-15Rβ by CD8 memory cells, indicating that IL-15 interacted directly with the T cells. These results indicate that transpresentation of IL-15 by IL-15Rα on BM-derived cells mediates the basal proliferation of memory CD8 T cells. (Blood. 2004;103:988-994)

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Cross-priming CD8+ T cells by targeting antigens to human dendritic cells through DCIR

Blood ◽

10.1182/blood-2010-01-264960 ◽

2010 ◽

Vol 116 (10) ◽

pp. 1685-1697 ◽

Cited By ~ 138

Author(s):

Eynav Klechevsky ◽

Anne-Laure Flamar ◽

Yanying Cao ◽

Jean-Philippe Blanck ◽

Maochang Liu ◽

...

Keyword(s):

T Cells ◽

Dendritic Cells ◽

T Cell ◽

Cd8 T Cells ◽

T Cell Responses ◽

Cd8 T Cell ◽

T Cell Immunity ◽

Cross Presentation ◽

Cell Responses ◽

Cell Immunity

Abstract We evaluated human CD8+ T-cell responses generated by targeting antigens to dendritic cells (DCs) through various lectin receptors. We found the immunoreceptor tyrosine-based inhibitory motif-containing DC immunoreceptor (DCIR) to mediate potent cross-presentation. A single exposure to a low dose of anti-DCIR–antigen conjugate initiated antigen-specific CD8+ T-cell immunity by all human DC subsets including ex vivo–generated DCs, skin-isolated Langerhans cells, and blood myeloid DCs and plasmacytoid DCs. The delivery of influenza matrix protein (FluMP) through DCIR resulted in expansion of FluMP-specific memory CD8+ T cells. Enhanced specific CD8+ T-cell responses were observed when an antigen was delivered to the DCs via DCIR, compared with those induced by a free antigen, or antigen conjugated to a control monoclonal antibody or delivered via DC-SIGN, another lectin receptor. DCIR targeting also induced primary CD8+ T-cell responses against self (MART-1) and viral (HIV gag) antigens. Addition of Toll-like receptor (TLR) 7/8 agonist enhanced DCIR-mediated cross-presentation as well as cross-priming, particularly when combined with a CD40 signal. TLR7/8 activation was associated with increased expansion of the primed CD8+ T cells, high production of interferon-γ and tumor necrosis factor-α, and reduced levels of type 2–associated cytokines. Thus, antigen targeting via the human DCIR receptor allows activation of specific CD8+ T-cell immunity.

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Specific CD8+ TCR Repertoire Recognizing Conserved Antigens of SARS-CoV-2 in Unexposed Population: A Prerequisite for Broad-Spectrum CD8+ T Cell Immunity

Vaccines ◽

10.3390/vaccines9101093 ◽

2021 ◽

Vol 9 (10) ◽

pp. 1093

Author(s):

Wei Hu ◽

Meifang He ◽

Xiaoning Wang ◽

Qiang Sun ◽

Ming Kuang

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Broad Spectrum ◽

Cd8 T Cell ◽

T Cell Immunity ◽

Healthy Population ◽

Cell Immunity ◽

Wide Range ◽

Tcr Repertoire

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has developed variants escaping neutralization antibody immunity established against the original virus. An understanding of broad-spectrum adaptive immunity, including CD8+ T cell immunity to wide range of epitopes, could help translational efforts to improve coronavirus disease 2019 (COVID-19) prevention and therapy. However, there have been few direct studies in which such immunity exists in a population. Methods: We selected SARS-CoV-2-conserved structural peptides that are not prone to mutation as antigens for broad-spectrum CD8+ T cell immunity. Peripheral blood mononuclear cells (PBMCs) from unexposed healthy donors were stimulated with these peptides in vitro and CD8+ T cell-specific response was monitored. The conserved peptide-specific CD8+ T cells were sorted for T cell receptor (TCR) repertoire sequencing. The presence of specific complementary determining region 3 (CDR3) clones was analyzed in a healthy cohort. Results: For each structural protein, including S, E, M, N, the conserved peptides could potentially provide the largest number of major histocompatibility complex-I (MHC-I) epitopes in the Oriental and Caucasian populations. For conserved peptides from spike (S), envelope (E), membrane (M), nucleocapsid (N) proteins, we found that there were no cross-reactive memory T cells in the unexposed individuals. Instead, their T cells contain naïve TCR repertoire recognizing these conserved peptides. Using TCR sequencing and CDR3 clustering for the conserved peptides specific T cells, we found that the recovered patients had a higher proportion of TCR repertoire similar with that of specific CD8+ T cells in unexposed individuals. Meanwhile, CDR3 clones of the above T cells were widely present in the healthy population. Conclusions: This study provides evidence of broad-spectrum SARS-CoV-2 specific CD8+ TCR repertoire in unexposed healthy population, which is implicated in the development and implementation of broad-spectrum vaccines against COVID-19.

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Monocytic Myeloid-Derived Suppress Cells Restore Adipogenic Bone Marrow Microenvironment in Aplastic Anemia By Inhibiting Intra-BM CD8+ T Cells Proliferation

Blood ◽

10.1182/blood-2019-125059 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1211-1211

Author(s):

Ying Qu ◽

Zhengxu Sun ◽

Yan Yuan ◽

Fen Wang ◽

Kunpeng Wu ◽

...

Keyword(s):

Bone Marrow ◽

Cell Proliferation ◽

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

T Cell Proliferation ◽

Immune Balance ◽

Ifn Γ

Aplastic anemia (AA) is a hematopoietic disorder resulted from immune-related hypocellular hematopoiesis in bone marrow (BM). It has been clearly addressed that the activated T cells contribute to the exhaustion of hematopoietic progenitors and hypo-hematopoiesis. The adipogenic BM is one of the characteristics to make AA diagnosis. However, little is known about the relationship of intra-BM immune imbalance and hematopoietic microenvironment abnormity in this disease entity. Functional hematopoiesis relies on not only abundant hematopoietic stem cells (HSCs) but also the balanced supportive hematopoietic niche. Intra-BM immune balance, at either cellular or cytokine level, is one of the key footstones to maintain hematopoietic microenvironment. Various intra-BM immune cellular components play both sides of one coin. Among them, myeloid-derived suppressive cells (MDSCs) are heterogeneous myeloid progenitor cells characterized by the negative immune response in cancers and other inflammatory diseases. In BM aspiration and biopsy samples from the patients who were diagnosed as AA in our study, massive activated lymphocytes infiltration and adipocytes accumulation were observed. Interestingly, the absolute numbers of immune modulatory MDSCs either in AA patients' PB or in BM of immune-related AA mice were reduced, indicating a potential link between polarized BM adipo-osteogenic microenvironment and immune disorder under AA circumstance. We thus adopted AA mice model to look into the embedded details both in vivo and in vitro. We clarified that BM components were more vulnerable to the attack of CD8+ T cells than that of CD4+ T cells. Taking into the fact that BM adipocytes are more abundant either in AA patients or in AA mice models, we differentiated mesenchymal stromal cells (MSCs), the major BM stroma cells, into osteoblastic or adipogenic lineages to mimic the osteo-adipogenic differentiation in BM microenvironment. Interestingly, CD8+ T cells and interferon-γ(IFN-γ) exerted dramatically adipocytic stimulation on BM-MSCs either in vitro or in vivo, by determination of increasing expression of adipogenetic genes including Ap2, Perilipin, Pparg and Cebpα, as well as staining of Oil Red O and perilipin. To dissect intra-BM cellular immune balance, MDSCs were isolated as representative immune regulating population to investigate their function on osteo-adipogenic balance. Interestingly, not CD11b+Ly6G+Ly6C-granulocytic-MDSCs (gMDSCs) but CD11b+Ly6G-Ly6C+monocytic-MDSCs (mMDSCs) inhibited both T cell proliferation and IFN-γ production. Addition of L-NMMA, the antagonist of iNOS pathway in mMDSCs-containing system restored T cell proliferative curve and cell numbers, whereas Nor-NOHA, the antagonist of Arg-1 pathway didn't abrogate mMDSCs' immune-regulation properties, indicating that mMDSCs inhibited T cell proliferation via iNOS pathway. We then performed single dose or multi-dose injection of mMDSCs in AA mice to see whether mMDSCs are able to reconstitute the impacted hematopoiesis. Single injection of mMDSCs was able to prevent from CTL infiltration in a very short term. However, multi-injection of mMDSCs showed significant benefit in overall survival rate compared to AA mice. We further detected the function of mMDSCs on polarized BM-MSCs adipo-osteogenic differentiation potential. To detect sequential BM adipogenetic progression in AA microenvironment, we performed in vivo fluorescent microscopy on AP2 (Fabp4)-Cre×mT/mG reporting mice at different transfusion time points of T cells and mMDSCs. GFP-expressing AP2+ adipocytes accumulated adjacently to perivascular niches whose boarders were labelled by Dextran-CY5 in a time-dependent manner after T cell infusion. Monocytic MDSCs transfused AA mice showed decreased GFP+ adipocytes which was coincident with our in vitro findings. In conclusion, intra-BM immune balance is one of the environmental factors seesawing by activating and suppressive ends to support functional hematopoiesis. Adoptive transfusion of mMDSCs, the immune-suppressive population might be a novel immune-regulating strategy to treat AA, relying on not only restoring the intra-BM immune balance but also improving stroma's multi-differentiating microenvironment. Figure Disclosures No relevant conflicts of interest to declare.

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