CD26 Blockade by Humanized Monoclonal Antibody Leads to Prophylaxis and Treatment of Graft-Versus-Host Disease (GVHD) in Hu-PBL-NOG Model Mice,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4018-4018
Author(s):  
Ryo Hatano ◽  
Kei Ohnuma ◽  
Taketo Yamada ◽  
Takaaki Ooki ◽  
Junpei Yamamoto ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Human Lymphocytes ◽  
Graft Versus Host ◽  
Human T Cells

Abstract Abstract 4018 CD26 is a 110-kDa multifunctional membrane-bound glycoprotein with dipeptidyl peptidase IV (DPPIV) enzyme activity present on a wide variety of cells, and is critical in T cell biology, as a marker of T cell activation. The role of CD26 in immune regulation has been extensively characterized, with our recent findings elucidating its linkage with signaling pathways and structures involved in T cell activation as well as antigen presenting cell (APC)-T cell interaction. CD26 in human T cells has a costimulatory function and is upregulated after activation. On the other hand, in murine lymphocytes, CD26 is expressed in CD4-CD8- thymocytes and its expression level is not changed by various stimulation procedures. Moreover, murine T cells are not observed to be activated via CD26. Therefore, for the analysis of CD26-mediated immuneregulation leading to clinical applications, it is necessary to use a pathological model system caused by human T cells but not murine T cells. For this purpose, we used a xenogeneic graft-versus-host disease (x-GVHD) murine model, which is generated by transplantation of human T cells into NOG-Scid mice (hu-PBL-NOG). In this model mouse, x-GVHD is developed by manifesting rough hair, loss of weight and motility, since transplanted human T cells become effector cells in murine organs. By examining the cytotoxic functions of human CD8+ T cells after CD26-mediated costimulation in vitro, we have shown that CD26-mediated costimulation induced vigorous secretion of inflammatory cytokines, TNF-a, IFN-g and soluble Fas Ligand, and strongly enhanced the expression of Granzyme B. These results suggested that cytotoxic function in human CD8+ T cells activated via CD26-mediated costimulation has a key role in developing x-GVHD. In the present study, we showed that CD26 blockade by humanized anti-CD26 monoclonal antibody (huCD26mAb) reduced development of x-GVHD, and that this effect of CD26 blockade was exerted by suppression of cytotoxic activity of human CD8+ T cells in vivo. Moreover, huCD26mAb showed as same effect on suppression of x-GVHD as clinically available drug, abatacept (CTLA4-Ig), a blockade of CD28-mediated costimulation. While increased dose of CTLA4-Ig showed more suppressive effect on x-GVHD but sustained suppression of engraftment of transplanted human T cells, the same dose of huCD26mAb showed no delay in engraftment. We performed a further analysis of peripheral human lymphocytes in hu-PBL-NOG after administration of huCD26mAb or CTLA4-Ig. Although CD26 expression on both human CD4+ T cells and CD8+ T cells was markedly increased in control mice with human IgG administration as compared with those before transplantation, the engraftment of human CD26+ T cells was completely inhibited in huCD26mAb administered hu-PBL-NOG. As a result of analysis of human T cells engrafted in spleen of NOG-Scid mice transplanted with carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled human lymphocytes, huCD26mAb administration preferentially suppressed the priming of human CD8+ T cells rather than CD4+ T cells, while CTLA4-Ig strongly suppressed the cell division of both human CD4+ T cells and CD8+ T cells. Our data strongly suggested that CD26-mediated costimulatory activation in human CD8+ T cells was deeply involved in the pathogenesis of x-GVHD, and blocking the CD26-mediated costimulation resulted in prophylaxis and treatment of x-GVHD. Taken together, our results support the notion that CD26 blockade by huCD26mAb may become a promising therapeutic strategy for GVHD and other refractory immune-mediated disorders. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Activation of CD4+ T cells in the presence of a nondepleting monoclonal antibody to CD4 induces a Th2-type response in vitro.

1995 ◽  
Vol 182 (1) ◽  
pp. 5-13 ◽  
Author(s):  
P Stumbles ◽  
D Mason
Keyword(s):  
Monoclonal Antibody ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Primary Cultures ◽  
In Vitro Experiments ◽  
Ifn Gamma

In vitro experiments using purified rat CD4+ T cells in primary and secondary mixed leukocyte cultures (MLC) have been carried out to explore the mechanism of inhibition of cell-mediated autoimmune disease in the rat by a nondepleting monoclonal antibody (mAb) to CD4. Previous work has shown that W3/25, a mouse anti-rat CD4 mAb of immunoglobulin G1 isotype, completely prevents the development of the paralysis associated with experimental allergic encephalomyelitis (EAE) in Lewis rats, but does so without eliminating the encephalitogenic T cells. The in vitro experiments described in this study have shown that when CD4+ T cells were activated in the presence of the anti-CD4 mAb in a primary MLC, the synthesis of interferon (IFN) gamma, but not interleukin (IL) 2, was completely inhibited. After secondary stimulation, now in the absence of the mAb, the synthesis of IL-4 and IL-13 mRNA was greatly enhanced compared with that observed from CD4+ T cells derived from primary cultures in which the mAb was omitted. As IL-4 and IL-13 are known to antagonize cell-mediated immune reactions, and as EAE is cell-mediated disease, the data suggest that the W3/25 mAb controls EAE by modifying the cytokine repertoire of T cells that respond to the encephalitogen. The capacity for the mAb to suppress IFN-gamma synthesis provides, in part, an explanation for this change in cytokine production. These findings are discussed in terms of what is known of the factors that determine which cytokine genes are expressed on T cell activation. Possible implications for the evolution of T cell responses in human immunodeficiency virus infection are also discussed.

scholarly journals c-Jun NH2-Terminal Kinase (JNK)1 and JNK2 Have Distinct Roles in CD8+ T Cell Activation

2002 ◽  
Vol 195 (7) ◽  
pp. 811-823 ◽  
Author(s):  
Dietrich Conze ◽  
Troy Krahl ◽  
Norman Kennedy ◽  
Linda Weiss ◽  
Joanne Lumsden ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Cd8 T Cell ◽  
Cell Surface Expression ◽  
Chain Gene ◽  
Α Chain

The c-Jun NH2-terminal kinase (JNK) signaling pathway is induced by cytokines and stress stimuli and is implicated in cell death and differentiation, but the specific function of this pathway depends on the cell type. Here we examined the role of JNK1 and JNK2 in CD8+ T cells. Unlike CD4+ T cells, the absence of JNK2 causes increased interleukin (IL)-2 production and proliferation of CD8+ T cells. In contrast, JNK1-deficient CD8+ T cells are unable to undergo antigen-stimulated expansion in vitro, even in the presence of exogenous IL-2. The hypoproliferation of these cells is associated with impaired IL-2 receptor α chain (CD25) gene and cell surface expression. The reduced level of nuclear activating protein 1 (AP-1) complexes in activated JNK1-deficient CD8+ T cells can account for the impaired IL-2 receptor α chain gene expression. Thus, JNK1 and JNK2 play different roles during CD8+ T cell activation and these roles differ from those in CD4+ T cells.

T Cell Activation and Regulation in Graft-Versus-Host Disease: Integral Role of CD28, CTLA4 and GITR Splice Variants.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3054-3054
Author(s):  
Yuji Miura ◽  
Christopher J. Thoburn ◽  
Emilie C. Bright ◽  
Elizabeth C. Matsui ◽  
William H. Matsui ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cell Activation ◽  
Splice Variants ◽  
Treg Cells ◽  
Mrna Splice ◽  
Graft Versus Host

Abstract Graft-versus-host disease (GVHD) is a serious, life-threatening complication that occurs following allogeneic (allo) bone marrow transplantation (BMT). The use of non-specific immunosuppression or T cell depletion has reduced the incidence of GVHD but at the expense of increased rates of infection and leukemic relapse. Modulation of the major costimulatory pathway (CD28/CTLA4:B7) involved in T cell activation and regulation may lead to specific immune tolerance in the absence of global non-specific immunosuppression. The identification of mRNA splice variants encoding for soluble forms of CD28, CTLA4 and GITR suggests that costimulation of T cells is complex and is not limited to cell-cell contact. The present studies examined the hypothesis that the onset of GVHD and the re-establishment of immune tolerance correlate with the expression levels of these costimulatory molecules. mRNA transcript levels for the soluble (s) and full-length (fl; cell surface associated) variants assessed by quantitative PCR, were temporally examined in peripheral blood lymphocytes (PBLs) from patients undergoing alloBMT (n=38) or autologous (auto) BMT (n=39) with the induction of autoGVHD by cyclosporin A treatment post-transplant. Levels of s and fl CD28 mRNA transcripts in PBLs were significantly increased (>1.5 fold, P<0.05) in patients developing either allo or autoGVHD compared to patients who do not develop GVHD. s and flCTLA4 levels in patients at the onset of allo and autoGVHD were significantly decreased compared to healthy controls (n=22) (>2.3-fold, P<0.01). s and flCTLA4 expression in patients with autoGVHD was significantly decreased compared to patients without autoGVHD (>2.1-fold). sCTLA4 expression in patients with alloGVHD was significantly decreased than patients without alloGVHD. Interestingly, temporal analysis revealed that the levels for sCTLA4 paralleled the recovery from GVHD implicating an active process in the establishment of non-responsiveness. CD28, CTLA4 and GITR s and fl mRNA levels in CD4+CD25+ T regulatory (Treg) cells from allo and autoBMT patients were significantly increased (7-, 41- or 22-fold, P<0.01) compared to the CD4+CD25− subset. Additional studies attempted to identify the potential role of the sCTLA4 protein (encoded by the mRNA splice variant) on the regulation of the lymphocyte response mediated by Treg cells. Addition of the Treg cells to a mixed lymphocyte reaction suppressed the proliferative response of CD8+ T cells to alloantigens (75% suppression; >4 fold reduction of 3H-thymidine incorporation). However, pretreatment of the Treg subset with short interfering RNA (siRNA) to knockdown sCTLA4 gene (confirmed by quantitative PCR) significantly reduced the ability of these cells to suppress the response (minimal suppression was detected, 6%). In vitro siRNA studies also indicated that Treg cells with inhibited sCTLA4 expression were unable to suppress the response of IL-2-stimulated autoreactive CD8+ T cells. Taken together, the results indicate that increased expression of CTLA4 (soluble and cell-surface associated) and the “negative” signal delivered by this molecule to the T cell may regulate the development of GVHD and help to re-establish self tolerance after BMT. Defining the role of costimulation and the modulation of this pathway on immune recognition and regulation not only provides opportunities to enhance the re-establishment of tolerance but also may help to intensify anti-tumor immunotherapeutic strategies.

PI3K-Independent Signaling Pathways Contribute to ICOS-Mediated T-Cell Costimulation in Acute Graft-Versus-Host Disease in Mice.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3003-3003
Author(s):  
Jun Li ◽  
Julie Leconte ◽  
Kenrick Semple ◽  
Jessica Heinrichs ◽  
Claudio Anasetti ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cell Activation ◽  
Acute Gvhd ◽  
Calcium Flux ◽  
Pi3k Signaling ◽  
Graft Versus Host ◽  
Acute Graft

Abstract Abstract 3003 ICOS provides an important costimulation to promote T-cell activation and function. Using a knock-in mouse strain, termed ICOS-YF, in which the cytoplasmic tail of ICOS cannot activate phosphoinositide 3-kinase (PI3K), we have shown that ICOS-PI3K signaling axis is critical for the generation of follicular helper T cells. We also observed that, in both CD4+ and CD8+ T cells, ICOS could potentiate TCR-mediated calcium flux in a PI3K-independent manner in vitro. Although ICOS can potentiate TCR-mediated calcium flux independent of PI3K, its biological significance is unclear. To address this question, we studied the function of ICOS-YF T cells in comparison with ICOS wild-type (WT) and knock-out (KO) T cells in MHC-mismatched bone marrow transplantation (BMT) models. Severity of acute graft-versus-host disease (GVHD) was evaluated based on recipient survival, body weight change, and pathologic scores. Consistent with the data previously published by us and others, ICOS KO T cells had significantly reduced ability to cause acute GVHD as compared to WT T cells. We further observed that YF T cells were significantly more capable in causing GVHD than KO T cells, but less capable than WT T cells. Mechanically, the levels of serum TNFa and IFNg were similar in the recipients of YF or KO T cells, but significantly lower than those of WT T cells. However, on the per-cell basis, YF CD8+ T cells expressed similar levels of intracellular IFNg as WT T cells, but significantly higher than KO T cells. We further compared the ability of CD4+ or CD8+ T cells alone in the induction of acute GVHD, and found that CD4+ T cells from YF and KO mice were similarly impaired in their capacity to induce acute GVHD. In contrast, the pathogenic capacity of CD8+ T cells from YF mice was comparable to that of WT cells, whereas KO CD8+ T cells were significantly less pathogenic. These results suggest that although both CD4+ and CD8+ T cells depend on ICOS costimulation, the downstream signaling pathways they utilize are distinct: CD4+ T cells depend on ICOS-PI3K signaling whereas CD8+ T cells are more dependent on PI3K-independent pathways, probably calcium signaling. Taken together, our study reveals a complexity in ICOS signaling mechanisms in T cell activation and GVHD induction. Disclosures: No relevant conflicts of interest to declare.

scholarly journals CTLA-4 dysregulation of self/tumor-reactive CD8+ T-cell function is CD4+ T-cell dependent

Blood ◽  
2006 ◽  
Vol 108 (12) ◽  
pp. 3818-3823 ◽  
Author(s):  
Luca Gattinoni ◽  
Anju Ranganathan ◽  
Deborah R. Surman ◽  
Douglas C. Palmer ◽  
Paul A. Antony ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Cell Function ◽  
Cd8 T Cell ◽  
Peripheral Tolerance ◽  
The Impact

AbstractCytotoxic T lymphocyte–associated antigen 4 (CTLA-4) maintains peripheral tolerance by suppressing T-cell activation and proliferation but its precise role in vivo remains unclear. We sought to elucidate the impact of CTLA-4 expression on self/tumor-reactive CD8+ T cells by using the glycoprotein (gp) 100–specific T-cell receptor (TCR) transgenic mouse, pmel-1. pmel-1 CLTA-4–/– mice developed profound, accelerated autoimmune vitiligo. This enhanced autoimmunity was associated with a small but highly activated CD8+ T-cell population and large numbers of CD4+ T cells not expressing the transgenic TCR. Adoptive transfer of pmel-1 CLTA-4–/– CD8+ T cells did not mediate superior antitumor immunity in the settings of either large established tumors or tumor challenge, suggesting that the mere absence of CTLA-4–mediated inhibition on CD8+ T cells did not directly promote enhancement of their effector functions. Removal of CD4+ T cells by crossing the pmel-1 CLTA-4–/– mouse onto a Rag-1–/– background resulted in the complete abrogation of CD8+ T-cell activation and autoimmune manifestations. The effects of CD4+ CLTA-4–/– T cells were dependent on the absence of CTLA-4 on CD8+ T cells. These results indicated that CD8+ CLTA-4–/– T-cell–mediated autoimmunity and tumor immunity required CD4+ T cells in which the function was dysregulated by the absence of CTLA-4–mediated negative costimulation.

scholarly journals Association of HLA Genotype With T-Cell Activation in Human Immunodeficiency Virus (HIV) and HIV/Hepatitis C Virus–Coinfected Women

2019 ◽  
Vol 221 (7) ◽  
pp. 1156-1166
Author(s):  
Andrea A Z Kovacs ◽  
Naoko Kono ◽  
Chia-Hao Wang ◽  
Daidong Wang ◽  
Toni Frederick ◽  
...  
Keyword(s):  
T Cells ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Immunodeficiency Virus ◽  
The Relationship

Abstract Background Global immune activation and HLA alleles are each associated with the pathogenesis of human immunodeficiency virus (HIV) and hepatitis C virus . Methods We evaluated the relationship between 44 HLA class I and 28 class II alleles and percentages of activated CD8 (CD8+CD38+DR+) and CD4 (CD4+CD38+DR+) T cells in 586 women who were naive to highly active antiretroviral therapy. We used linear generalized estimating equation regression models, adjusting for race/ethnicity, age, HIV load, and hepatitis C virus infection and controlling for multiplicity using a false discovery rate threshold of 0.10. Results Ten HLA alleles were associated with CD8 and/or CD4 T-cell activation. Lower percentages of activated CD8 and/or CD4 T cells were associated with protective alleles B*57:03 (CD8 T cells, −6.6% [P = .002]; CD4 T cells, −2.7% [P = .007]), C*18:01 (CD8 T cells, −6.6%; P < .0008) and DRB1*13:01 (CD4 T cells, −2.7%; P < .0004), and higher percentages were found with B*18:01 (CD8 T cells, 6.2%; P < .0003), a detrimental allele. Other alleles/allele groups associated with activation included C*12:03, group DQA1*01:00, DQB1*03:01, DQB1*03:02, DQB1*06:02, and DQB1*06:03. Conclusion These findings suggest that a person’s HLA type may play a role in modulating T-cell activation independent of viral load and sheds light on the relationship between HLA, T-cell activation, immune control, and HIV pathogenesis.

scholarly journals Gamma Interferon Responses of CD4 and CD8 T-Cell Subsets Are Quantitatively Different and Independent of Each Other during Pulmonary Mycobacterium bovis BCG Infection

2007 ◽  
Vol 75 (5) ◽  
pp. 2244-2252 ◽  
Author(s):  
Patricia Ngai ◽  
Sarah McCormick ◽  
Cherrie Small ◽  
Xizhong Zhang ◽  
Anna Zganiacz ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Mycobacterial Infection ◽  
Cd8 T Cell ◽  
T Cell Subsets ◽  
Ifn Γ

ABSTRACT Gamma interferon (IFN-γ) is a key cytokine in host defense against intracellular mycobacterial infection. It has been believed that both CD4 and CD8 T cells are the primary sources of IFN-γ. However, the relative contributions of CD4 and CD8 T-cell subsets to IFN-γ production and the relationship between CD4 and CD8 T-cell activation have not been examined. By using a model of pulmonary mycobacterial infection and various immunodetection assays, we found that CD4 T cells mounted a much stronger IFN-γ response than CD8 T cells at various times after mycobacterial infection, and this pronounced IFN-γ production by CD4 T cells was attributed to both greater numbers of antigen-specific CD4 T cells and a greater IFN-γ secretion capacity of these cells. By using major histocompatibility complex class II-deficient or CD4-deficient mice, we found that the lack of CD4 T cells did not negatively affect primary or secondary CD8 T-cell IFN-γ responses. The CD8 T cells activated in the absence of CD4 T cells were capable of immune protection against secondary mycobacterial challenge. Our results suggest that, whereas both CD4 and CD8 T cells are capable of IFN-γ production, the former represent a much greater cellular source of IFN-γ. Moreover, during mycobacterial infection, CD8 T-cell IFN-γ responses and activation are independent of CD4 T-cell activation.

Targeting of alpha4beta1 Integrin and CD4/CD8 on Human T Cells, in Addition to CD3 and CD28, Induces Maximal Activation, as Assessed by Single-Cell Analysis of MAP Kinase Pathway Activation and Cytokine Production.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1538-1538
Author(s):  
Tae Kon Kim ◽  
Matthew J. Billard ◽  
Eric D. Wieder ◽  
Bradley W. McIntyre ◽  
Krishna V. Komanduri
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cell Activation ◽  
Low Dose ◽  
Synapse Formation ◽  
Signal Model ◽  
Human T Cells ◽  
Ifng Production

Abstract Optimal T cell activation requires the formation of immunological synapses between T cells and antigen-presenting cells (APC). Immunological synapse formation involves the binding of ligands on APC to co-stimulatory receptors on T cells, resulting in maximal activation. Most prior in vitro studies examining the process of T cell activation have utilized immobilized mAbs or ligands to assess the roles of co-stimulatory molecules in T cell activation. Micro-domain formation in such models may be inflexible, potentially yielding misleading results about the relative importance of individual costimulatory pathways. To more physiologically mimic immunologic synapse formation, we stimulated T cells with soluble primary mAbs that were then cross-linked by secondary antibodies. Specifically, we induced cross-linking of surface proteins on purified human T cells using a combination of mAbs recognizing four potential co-stimulatory receptors (CD3, CD4 or CD8, CD28 and VLA4/a4b1 integrin), and assessed phospho-Erk1/2 and cytokine production at a single cell level using flow cytometry. Consistent with the predictions of the Bretscher-Cohn two-signal model, CD28 induced a modest increase in Erk1/2 phosphorylation (in CD4) and IL-2 production (in CD4+ and CD8+ T cells) and IFNg (in CD8+ T cells), while low dose (0.1mcg/ml) anti-CD3 mAb alone failed to induce significant activation (P<0.05). However, CD28 stimulation consistently augmented activation in both CD4+ and CD8+ T cells in the presence of anti-CD4 and anti-CD8 mAbs (P<0.05). More interestingly, stimulation by CD4 or CD8 mAbs induced an additive effect on Erk1/2 phosphorylation and IL-2 and IFNg production regardless of CD28 stimulation (P<0.05). In addition, stimulation via a4b1/VLA4 increased the level of T cell activation in the presence of three distinct signals in both CD4+ T cells and also in CD8+ T cells (P<0.05). We then examined the dependence of T cell activation on all four types of stimuli (i.e., via CD3, CD28, CD4 or CD8, and VLA4). Following stimulation with low-dose anti-CD3 mAb (0.1mcg/ml), the extent of Erk1/2 phosphorylation and IL-2/IFNg production was found to be dependent on the numbers of stimulatory signals received through all four pathways in a statistically meaningful manner (see Figure). In conclusion, optimal T cell activation requires not only CD3 and CD28, but also signaling via CD4/CD8 and VLA4, supporting a “four-signal” model of T cell activation. These data suggest that additional co-stimulations through a4b1/VLA4 and CD4 or CD8 may be necessary to induce optimal T cell signaling, targeting of a4b1 and CD4/CD8 by specific agonists or antagonists may have therapeutic benefit in immunomodulation (e.g., augmentation of vaccine responses and/or abrogation of pathogenic T cell activation). Figure Figure

Blocking ICOS-B7h Signal Can Inhibit the Function of Allogene T Lymphocytes and Decrease the Incidence and Severity of Acute Graft Versus Host Disease in Mouse Model

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4606-4606
Author(s):  
Xiaochen Bao ◽  
Ningxia Song ◽  
Bin Wang ◽  
Jianmin Wang
Keyword(s):  
T Cells ◽  
T Cell ◽  
Fusion Protein ◽  
T Cell Activation ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Recipient Mouse ◽  
T Helper ◽  
Graft Versus Host ◽  
Ifn Γ

Abstract ICOS, a CD28 family member expressed on activated T cells, plays important roles in T cell activation and effector function. Here we report our results of biological activity of ICOS signal on allogeneic T lymphocytes and its effect on acute graft-versus-host disease in mouse model by blocking ICOS-B7h signal with ICOS-Ig fusion protein. Human ICOSIg fusion protein was harvested and purified from supernatant of CHO cells transfected with pSecTag2/Hygro A-ICOS-Ig in our lab. Spleen CD4+ cells from C57BL/6 mouse were stimulated with dendritic cells from BALB/C mouse, with different doses of ICOS-Ig or human-Ig (h-Ig) as controls. Allogeneic aGVHD model was established with lethally irradiated BALB/c recipients receiving allogeneic BM and spleen T cells from C57BL/6 mouse with 100ug ICOS-Ig or h-Ig intropenetoneally 4 times at day 0, day +2, +4 and +6 of transplantation. RESULTS: ICOS-Ig (10ug/mL) significantly inhibited proliferation of CD4+T cells ( P<0.01), decreased the level of TNF-α and elevated level of IL-4 in the supernatants of CD4+ T cells in response to allogeneic mature DCs but had no effect on IFN-γ production; ICOS-Ig blockade elevated apoptosis of splenic CD4+ T cells while had no effect on T cell activation (CD25 expression). ICOS-Ig blockade significantly attenuated the lethal GVHD that occurred in control recipient mice. The average survival time was 13.25±5.87 days for mice in h-Ig group, while 21.42±3.02 days for animals in ICOS-Ig group(p=0.0217). Pathologic evaluation revealed that the liver and intestine of animals in ICOS-Ig group has less lymphocyte infiltration and less architectural disruption than those in control h-Ig group; In vivo, ICOS-Ig had no effect on allogeneic T cells division (h-Ig :98.40±1.32, ICOS-Ig: 97.69±2.19 by FACS analysis of CFSE labeled lymphocyte at day 3 of transplantation) and no effect on the proportion of CD4+/CD8+ (h-Ig: 26.35±0.07, ICOS-Ig: 22.12±0.21), but increased apoptosis of allogeneic CD8+ T cells in GVHD model by FACS analysis of Annexin-V staining lymphocytes at day 10 of transplantation (h-Ig: 20.44±3.83, ICOS-Ig: 22.87±6.94 in CD4+ T cells; h-Ig: 18.73±7.43, ICOS-Ig: 24.03±5.4 in CD8+ T cells). Spleen T cells from mice after transplantation were stimulated by ConA ex vivo, ICOS-Ig group proliferated less than control h-Ig group through cell counting with CCK-8 (h-Ig: 0.86±0.04,ICOS-Ig: 0.69±0.12,P<0.05). (4) ICOS-Ig significantly reduced the secretion of IFN-γ and elevated IL-4 in the serum of recipient mouse. The IFN-γ (pg/mL) detected were 562.27±49.97 in h-Ig group, 49.79±2.81 in ICOS-Ig group; and the IL-4 (pg/mL) detected were 38.819±27.56 in h-Ig group,456.03±69.63 in ICOS-Ig group. (p<0.05). (5)ICOS-Ig significantly reduced the secretion of T-bet and elevated GATA-3 in the spleens of recipient mouse. The T-bet/GATA-3 detected were 1.87±0.65 in h-Ig group, 0.56±0.03 in ICOS-Ig (p=0.03). CONCLUSION: The ICOS-Ig fusion protein had bioactivity of inhibition of T cell proliferation and alternated the polarization of T helper cells; It promoted the apoptosis of allo-reactive T cells from donor animals but had no effect on the activation of allo-reactive CD4+T cells; ICOS-Ig blockade can prevent aGVHD through attenuating the function of the allo-reactive T cells, elevating apoptosis of allo-reactive T cells and alternating the polarization of T helper cells.

Histone Deacetylase 6 (HDAC6) Influences T-Cell Activation and Survival: Implications For Cancer Immunotherapy

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1050-1050
Author(s):  
Andressa Sodre Laino ◽  
David M Woods ◽  
Fengdong Cheng ◽  
Hongwei Wang ◽  
Eduardo M. Sotomayor
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Survival ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Wild Type ◽  
T Cell Survival

Abstract The role of histone deacetylases (HDACs) as epigenetic regulators of immune function is becoming increasingly clear. Recently, the role of specific HDACs in orchestrating T-cell maturation, survival and function has begun to emerge, giving rationale to selective therapy to direct immune responses in different disease settings, including cancer. In particular, HDAC6 has recently been characterized as a negative regulator of regulatory T-cell suppressive activity (de Zoeten, Molecular and Cellular Biology, 2011). Here we report an expanded, novel role of HDAC6 in regulating T-cell survival and activation. First, the relative expression of the eleven classic HDACs was evaluated in resting and activated T-cells from mouse and human samples. It was found that the majority of HDACs decrease in expression following activation, including HDAC6. Next, in a HDAC6KO mouse model, it was found that T-cells lacking HDAC6 had skewed survival when compared to wild-type murine T-cells. This difference seems to be the result of an increased CD4+ T-cells population in the lymph nodes, with a concomitant decrease in viable CD8+ T-cells. To determine whether this population skewing was the consequence of defects in HDAC6KO mice T-cell development, wild-type murine T-cells were treated with an isotype-selective HDAC6 inhibitor. The results seen in HDAC6KO T-cells were recapitulated when wild-type T-cells were activated and treated with HDAC6 specific inhibitors, indicating a role of HDAC6 outside of thymic development in promoting CD4+ T-cell survival at the expense of CD8+ T-cells. Interestingly, it was found that activated CD4+ T-cells displayed decreased expression of the apoptosis signaling receptor FAS after HDAC6 inhibition while no differences were observed in CD8+ T-cells under the same conditions. In addition to these results implicating HDAC6 in regulating T-cell survival, expression of surface markers was altered in both CD8+ and CD4+ T-cells, including enhanced expression of the activation molecule CD69 in stimulated T-cells treated with an isotype-selective HDAC6 inhibitor. Finally, in vivo studies in tumor-bearing HDAC6KO mice revealed a significantly delayed in tumor progression. Similar results were observed in lymphoma-bearing mice treated with HDAC6 specific inhibitors. Taken together, this data shows that HDACs are dynamic in expression with regards to T-cell activation state. More specifically, we have unveiled hereto-unexplored roles of HDAC6 in regulating T-cell survival and function, pointing at this specific HDAC as an appealing target to harness T-cell immunity in hematologic malignancies. Disclosures: No relevant conflicts of interest to declare.

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