Necrosis Factor Receptor Family-related Gene Research Articles

Induction of CD4+CD25+Foxp3− regulatory T cells by Thy‐1 stimulation of CD4+ T cells

Thy-1 (CD90) on mouse T cells has been reported to have both T-cell activating and regulatory roles. In this study, we show that monoclonal antibody (mAb)-mediated crosslinking of Thy-1 on CD4(+) mouse T-cells-induced regulatory T (T(reg)) cells that expressed CD25, CD39 and glucocorticoid-induced tumor necrosis factor receptor family-related gene, but not CD73, CD122 or Foxp3. The proliferation of CD4(+) T(responder) cells in response to anti-CD3/anti-CD28mAb-coated T-cell expander beads or syngeneic dendritic cells and soluble anti-CD3mAb was inhibited by Thy-1-induced T(reg) cells, in spite of elevated IL-2 levels in the co-cultures. Interestingly, stimulation with T-cell expander beads caused Thy-1-induced T(reg) cells to synthesize large amounts of interleukin-2 (IL-2). IL-10 was also elevated in co-cultures of activated T(responder) cells and Thy-1-induced T(reg) cells. However, mAb-mediated neutralization of IL-10 did not restore T(responder)-cell proliferation to control levels, which excluded IL-10 as a potential mediator of Thy-1-induced T(reg)-cell suppressor function. In addition, Thy-1-induced T(reg) cells did not inhibit IL-2-dependent proliferation of CTLL-2 cells, suggesting that IL-2 receptor signaling remained intact in the presence of Thy-1-induced T(reg) cells. We suggest that T(reg) cells induced by Thy-1 ligation in vivo may contribute to the maintenance of T-cell homeostasis.

Immune rejection of mouse tumors expressing mutated self.

How the immune system recognizes and responds to mutations expressed by cancer cells is a critical issue for cancer immunology. Mutated self-polypeptides are particularly strong tumor-specific rejection antigens for natural tumor immunity, but we know remarkably little about T-cell responses to mutated self during tumor growth in vivo, including levels of response, kinetics, and correlates that predict tumor rejection. To address these questions, a mutated self-antigen, designated tyrosinase-related protein 1 (Tyrp1)-WM, derived from Tyrp1 was expressed in the poorly immunogenic, spontaneously arising B16 melanoma and the immunogenic, chemically induced LiHa fibrosarcoma. Syngeneic mice challenged with LiHa fibrosarcoma cells expressing Tyrp1-WM, but not native Tyrp1, induced specific CD8(+) and CD4(+) T-cell responses against defined mutated epitopes in tumor-draining lymph nodes and in tumors. Subsequently, specific CD8(+) T-cell responses contracted as a minority of tumors progressed. B16 melanomas expressing Tyrp1-WM induced minimal T-cell responses, and no tumor immunity was detected. Treatment with an agonist monoclonal antibody against glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR) increased the level of CD8(+) T cells recognizing a peptide derived from the Tyrp1-WM sequence and the proportion of mice rejecting tumors. These results show that B16 tumors expressing mutations that generate strongly immunogenic epitopes naturally induce T-cell responses, which are insufficient to reject tumors. Immune modulation, such as inducing GITR signaling, is required to enhance CD8(+) T-cell responses to specific mutations and to lead to tumor rejection.

Deficiency of forkhead box P3 and cytotoxic T‐lymphocyte‐associated antigen‐4 gene expressions and impaired suppressor function of CD4+CD25+ T cells in patients with autoimmune hepatitis

Recently, forkhead box P3 (Foxp3), cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR), and CD28 were identified as the key molecules that control the development and activation of CD4+CD25+ regulatory T cells (T-reg). We investigated the expression pattern of these molecules on T-reg, and investigated the ability of T-reg to produce cytokines in patients with autoimmune hepatitis (AIH). Fifteen patients with AIH and nine healthy patients were included. To determine the frequency of T-reg, a two-color flow cytometry analysis was performed. T-reg were isolated using immunomagnetic beads, and the mRNA levels of Foxp3, CTLA-4, GITR, and CD28 were quantified by real-time polymerase chain reaction (PCR). The ability of T-reg to produce interferon-gamma, interleukin (IL)-10, transforming growth factor-beta, and tumor necrosis factor-alpha after stimulation by OKT3 was evaluated by measuring the levels of mRNA in T-reg by real-time PCR. The frequency of T-reg was increased in AIH. The mRNA levels of Foxp3 and CTLA-4 were significantly lower in AIH. The ability of T-reg to produce IL-10 was impaired in AIH. We speculate that the inferiority of the Foxp3 and CTLA-4 gene expressions on T-reg results in the impaired suppressor function of T-reg, and eventually in the breakdown of self-tolerance.

Regulatory T Cell–Resistant CD8+ T Cells Induced by Glucocorticoid-Induced Tumor Necrosis Factor Receptor Signaling

We previously found that a Salmonella typhimurium vector engineered to secrete soluble tumor antigen induces CD4(+) T cells resistant to CD4(+)CD25(+) regulatory T cells (Treg) and that glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR) signal is involved in the development of this resistance. In this study, we address the potential of incorporating GITR ligand (GITRL) as a way to augment the immunogenicity of cancer vaccines. BALB/c mice were immunized by gene gun with plasmids encoding the mutated extracellular signal-regulated kinase 2 (mERK) with or without plasmids encoding mouse GITRL. Coadministration with GITRL during primary and secondary immunization enhanced the induction of mERK-specific CD8(+) T cells. Antibody depletion and minigene analysis suggested that GITRL directly activated CTL epitope-specific CD8(+) T cells independently of CD4(+) T cells. Immunization with plasmids encoding a CTL epitope and GITRL resulted in strong tumor inhibition in a CD8(+) T cell-dependent manner. Furthermore, CTL epitope-specific CD8(+) T cells induced by immunization with plasmids encoding CTL epitope coadministered with GITRL were refractory to suppression by CD4(+)CD25(+) Tregs compared with CD8(+) T cells induced without GITR signaling. We propose that coadministration of GITR signaling agents with tumor antigens constitutes a promising novel strategy for cancer vaccine development.

Basal lymphoid aggregates in ulcerative colitis colon: a site for regulatory T cell action

Regulatory T cells seem to play a central role in maintaining immune tolerance in the gut mucosa. Previously we have shown that interleukin (IL)-10 is produced at high levels in the inflamed colonic tissue of ulcerative colitis (UC) patients. The cellular source was CD4+ T cells, suggesting local activation of regulatory T cells. The present study was performed to determine whether the frequency of regulatory T cells is increased in UC colon and whether they are present in the basal lymphoid aggregates, the prominent microanatomical structure in UC colon. Colonic tissue specimens from UC and control patients were analysed for frequencies of lamina propria lymphocytes expressing the regulatory T cell markers forkhead box protein 3 (FoxP3), CD25 and glucocorticoid-induced tumour necrosis factor receptor family-related gene (GITR) as well as CD28, CD4 and CD3 by using marker specific reagents in immunomorphometry. Two-colour immunohistochemistry was used for detection of CD25/IL-10, FoxP3/IL-10 and CD25/FoxP3 double-positive cells. GITR+ and FoxP3+ cells were present in normal colon mucosa, although at a relatively low frequency, and were located preferentially within the solitary follicles. UC was associated with significantly increased frequencies of CD25+, GITR+ and FoxP3+ lamina propria lymphocytes both within the basal lymphoid aggregates and in the lamina propria outside. Many of the CD25+ cells co-expressed FoxP3 as well as IL-10, suggesting that these are indeed IL-10 secreting regulatory T cells, activated in an attempt to counteract the inflammation. Increased frequency of regulatory T cell subtypes seems insufficient to control the disease activity in UC.

Agonist Anti-GITR Antibody Enhances Vaccine-Induced CD8+ T-Cell Responses and Tumor Immunity

Immunization of mice with plasmids encoding xenogeneic orthologues of tumor differentiation antigens can break immune ignorance and tolerance to self and induce protective tumor immunity. We sought to improve on this strategy by combining xenogeneic DNA vaccination with an agonist anti-glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR) monoclonal antibody (mAb), DTA-1, which has been shown previously both to costimulate activated effector CD4(+) and CD8(+) T cells and to inhibit the suppressive activity of CD4(+)CD25(+) regulatory T cells. We found that ligation of GITR with DTA-1 just before the second, but not the first, of 3 weekly DNA immunizations enhanced primary CD8(+) T-cell responses against the melanoma differentiation antigens gp100 and tyrosinase-related protein 2/dopachrome tautomerase and increased protection from a lethal challenge with B16 melanoma. This improved tumor immunity was associated with a modest increase in focal autoimmunity, manifested as autoimmune hypopigmentation. DTA-1 administration on this schedule also led to prolonged persistence of the antigen-specific CD8(+) T cells as well as to an enhanced recall CD8(+) T-cell response to a booster vaccination given 4 weeks after the primary immunization series. Giving the anti-GITR mAb both during primary immunization and at the time of booster vaccination increased the recall response even further. Finally, this effect on vaccine-induced CD8(+) T-cell responses was partially independent of CD4(+) T cells (both helper and regulatory), consistent with a direct costimulatory effect on the effector CD8(+) cells themselves.

Signaling triggered by glucocorticoid-induced tumor necrosis factor receptor family-related gene: Regulation at the interface between regulatory T cells and immune effector cells

Mammals and other higher vertebrates have developed an adaptive immune system to defy effectively countless pathogens and cancerous cells encountered during the lifetime of an individual. B and T lymphocytes, which are essential in orchestrating adaptive immune responses, express surface receptors specific for foreign and abnormal self-antigens. Genesis of this antigen receptor repertoire poses significant risks for autoimmunity caused by self-reactive lymphocytes. Therefore, organisms with adaptive immune systems have evolved central and peripheral tolerance mechanisms. In peripheral tissues, regulatory T (Treg) cells function in a dominant, cell-extrinsic manner to limit inflammatory responses and autoimmune disorders. To tap the potential clinical utility of these specialized lymphocytes, advances have been made in understanding how Treg cell-mediated suppression of immune effector cells is achieved and regulated. Importantly, signaling induced by a recently identified member of the tumor necrosis factor receptor (TNFR) family, termed glucocorticoid-induced TNFR family-related gene (GITR), abrogates the suppressive effects of Treg cells. GITR plays a pivotal role in controlling T cell-mediated responses in experimental models of organ-specific autoimmunity, chronic infection, and anti-tumor immunity. These findings highlight the importance of elucidating the molecular underpinnings of GITR-induced signaling. We propose that GITR employs adapter proteins, including TNFR-associated factors (TRAFs), to regulate diverse signaling pathways and transcriptional programs that control the interplay between Treg cells and immune effector cells.

Definition of target antigens for naturally occurring CD4+ CD25+ regulatory T cells

The antigenic targets recognized by naturally occurring CD4+ CD25+ regulatory T cells (T reg cells) have been elusive. We have serologically defined a series of broadly expressed self-antigens derived from chemically induced mouse sarcomas by serological identification of antigens by recombinant expression cloning (SEREX). CD4+ CD25+ T cells from mice immunized with SEREX-defined self-antigens had strong suppressive activity on peptide-specific proliferation of CD4+ CD25− T cells and CD8+ T cells. The suppressive effect was observed without in vitro T cell stimulation. Foxp3 expression in these CD4+ CD25+ T cells from immunized mice was 5–10 times greater than CD4+ CD25+ T cells derived from naive mice. The suppressive effect required cellular contact and was blocked by anti-glucocorticoid–induced tumor necrosis factor receptor family–related gene antibody. In vitro suppressive activity essentially disappeared 8 wk after the last immunization. However, it was regained by in vitro restimulation with cognate self-antigen protein but not with control protein. We propose that SEREX-defined self-antigens such as those used in this study represent self-antigens that elicit naturally occurring CD4+ CD25+ T reg cells.

NFATc2 and NFATc3 transcription factors play a crucial role in suppression of CD4+ T lymphocytes by CD4+ CD25+ regulatory T cells

The phenotype of NFATc2−/− c3−/− (double knockout [DKO]) mice implies a disturbed regulation of T cell responses, evidenced by massive lymphadenopathy, splenomegaly, and autoaggressive phenomena. The population of CD4+ CD25+ T cells from DKO mice lacks regulatory capacity, except a small subpopulation that highly expresses glucocorticoid-induced tumor necrosis factor receptor family–related gene (GITR) and CD25. However, neither wild-type nor DKO CD4+ CD25+ regulatory T cells (T reg cells) are able to suppress proliferation of DKO CD4+ CD25− T helper cells. Therefore, combined NFATc2/c3 deficiency is compatible with the development of CD4+ CD25+ T reg cells but renders conventional CD4+ T cells unresponsive to suppression, underlining the importance of NFAT proteins for sustaining T cell homeostasis.

GITR activation induces an opposite effect on alloreactive CD4(+) and CD8(+) T cells in graft-versus-host disease.

Glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR) is a member of the tumor necrosis factor receptor (TNFR) family that is expressed at low levels on unstimulated T cells, B cells, and macrophages. Upon activation, CD4+ and CD8+ T cells up-regulate GITR expression, whereas immunoregulatory T cells constitutively express high levels of GITR. Here, we show that GITR may regulate alloreactive responses during graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation (BMT). Using a BMT model with major histocompatibility complex class I and class II disparity, we demonstrate that GITR stimulation in vitro and in vivo enhances alloreactive CD8+CD25− T cell proliferation, whereas it decreases alloreactive CD4+CD25− proliferation. Allo-stimulated CD4+CD25− cells show increased apoptosis upon GITR stimulation that is dependent on the Fas–FasL pathway. Recipients of an allograft containing CD8+CD25− donor T cells had increased GVHD morbidity and mortality in the presence of GITR-activating antibody (Ab). Conversely, recipients of an allograft with CD4+CD25− T cells showed a significant decrease in GVHD when treated with a GITR-activating Ab. Our findings indicate that GITR has opposite effects on the regulation of alloreactive CD4+ and CD8+ T cells.

GITR ACTIVATION IN DONOR SPECIFIC TRANSFUSION ACCELERATES ALLOGRAFT REJECTION

P1016 Aims: Glucocorticoid-induced tumour necrosis factor receptor family-related gene (GITR) is expressed at high levels by CD25+CD4+ regulatory T cells. We made murine transplantation model of which graft survival was prolonged by donor specific transfusion and investigate the function of CD25+CD4+ and CD25-CD4+ T cells under the impact of GITR activation. We studied how GITR ligation effects on antigen reactive T cells during the induction of specific unresponsiveness in vivo. Methods: We examined the impact of GITR ligation on cardiac allograft rejection. We made donor specific transfusion, DST model that BALB/c mice heart graft was transplanted to BL6 mice 7days after 107 BALB/c spleen cells were infused to BL6. Then we observed the graft survival in the presence and absence of GITR activation using agonistic GITR antibody, DTA-1, or control rat Ig. To monitor the fate of T cells in the presence and absence of GITR activation we investigated the absolute number and activation status of CD4+Vb6+ T cells responding to Mls1a. BALB/c mice were treated with either DTA-1 or control rat Ig before administration of DBA/2 spleen cells (DST). The absolute number and activation status of CD4+Vb6+ T cells present in the spleen and LN was determined by FACS on days 2 – 7 inclusive and on day 14 after DST. Results: DST 107 BALB/c spleen cells 7 days before transplantation can consistently prolong the survival of BALB/c heart grafts in BL6 mice compared with naïve BL6 mice. Administration of DTA-1 the day before DST not only prevented graft prolongation but also triggered accelerated rejection of the BALB/c heart allografts. The accelerated rejection response confirmed that the DTA-1 has dual effects on T cells responding to alloantigen in vivo. At later time points, day 6, 7 and 14, there was a decline in the absolute number of T cells responding to Mls1a superantigen reactive T cells. Treatment with either DTA-1 or control rat Ig alone in the absence of DST did not change the absolute number of CD4+Vb6+ present in the spleen or LN over the time course studied compared to the number present in untreated adult BALB/c mice. Conclusions: GITR activation at the time of alloantigen infusion triggers accelerated graft rejection. GITR agonists can therefore augments immune responsiveness in vivo by simultaneously targeting the immunoregulatory and effector arms of the immune response.

The paradoxical effect of glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR) activation on alloreactive CD4 and CD8 T cells and the development of GVHD

GITR is a member of the tumor necrosis factor receptor family and is involved in regulatory T cell function and TCR activation. GITR is expressed at low levels on resting T cells, B cells and macrophages. Upon activation, CD4+ and CD8+ T cells upregulate GITR expression while CD4+CD25+ regulatory T cells (Treg) constitutively express GITR. Treg stimulation through GITR inhibits their suppressor function and in vivo administration of GITR agonistic antibodies induce autoimmune disease. Here we show that GITR is a relevant molecule for immune responses in graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation (allo BMT). We used a MHC class I/II disparate model for murine allo BMT (C57BL/6 (B6) into BALB/c) to determine the effects of a GITR activating antibody (GITR Ab) on alloreactive T cells during the development of GVHD. We found that addition of GITR Ab to a mixed lymphocyte reaction (MLR) with irradiated BALB/c splenic stimulators, CD4+CD25− B6 effectors and B6 Tregs induced the blockade of Treg suppressor function, as previously described. Interestingly, GITR Ab also had a direct effect on CD4+CD25− and CD8+CD25− T cell populations. Addition of GITR Ab in an MLR showed a 2-fold decrease in CD4+CD25− proliferation while CD8+CD25− proliferation increased by 3.5-fold when compared to the control. Fas deficient CD4+CD25− T cells had an intact alloreactive proliferative response, suggesting that GITR can induce Fas-mediated apoptosis of CD4+CD25− alloreactive T cells. We used the adoptive transfer of CFSE-labeled donor CD3+ T cells into irradiated allogeneic recipients to assess the expression of GITR in vivo and found increased levels of GITR on both CD4+ and CD8+ dividing alloreactive T cells. When we administered the GITR Ab to allogeneic recipients of CD4+CD25− or CD8+CD25− CFSE-labeled T cells, we observed a 45% reduction in the number of donor CD4+CD25− CFSE-labeled T cells recovered at day 3 after infusion. In contrast, there was a 54% increase in the recovery of CFSE-labeled CD8+CD25− T cells. More importantly, mouse recipients of an allo BMT accompanied by CD8+CD25− donor T cells had increased morbidity and mortality in the presence of GITR Ab. Conversely, mice treated with GITR antibody that received allogeneic CD4+CD25− T cells in the allograft showed a significant decrease in GVHD. Our findings identify a novel and paradoxical effect of GITR stimulation on alloreactive T cells during the development of GVHD.

Stimulation of CD25(+)CD4(+) regulatory T cells through GITR breaks immunological self-tolerance.

CD25(+)CD4(+) regulatory T cells in normal animals are engaged in the maintenance of immunological self-tolerance. We show here that glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR, also known as TNFRSF18)--a member of the tumor necrosis factor-nerve growth factor (TNF-NGF) receptor gene superfamily--is predominantly expressed on CD25(+)CD4(+) T cells and on CD25(+)CD4(+)CD8(-) thymocytes in normal naïve mice. We found that stimulation of GITR abrogated CD25(+)CD4(+) T cell-mediated suppression. In addition, removal of GITR-expressing T cells or administration of a monoclonal antibody to GITR produced organ-specific autoimmune disease in otherwise normal mice. Thus, GITR plays a key role in dominant immunological self-tolerance maintained by CD25(+)CD4(+) regulatory T cells and could be a suitable molecular target for preventing or treating autoimmune disease.

Identification of a Novel Activation-inducible Protein of the Tumor Necrosis Factor Receptor Superfamily and Its Ligand

Among members of the tumor necrosis factor receptor (TNFR) superfamily, 4-1BB, CD27, and glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR) share a striking homology in the cytoplasmic domain. Here we report the identification of a new member, activation-inducible TNFR family member (AITR), which belongs to this subfamily, and its ligand. The receptor is expressed in lymph node and peripheral blood leukocytes, and its expression is up-regulated in human peripheral mononuclear cells mainly after stimulation with anti-CD3/CD28 monoclonal antibodies or phorbol 12-myristate 13-acetate/ionomycin. AITR associates with TRAF1 (TNF receptor-associated factor 1), TRAF2, and TRAF3, and induces nuclear factor (NF)-kappaB activation via TRAF2. The ligand for AITR (AITRL) was found to be an undescribed member of the TNF family, which is expressed in endothelial cells. Thus, AITR and AITRL seem to be important for interactions between activated T lymphocytes and endothelial cells.

A new member of the tumor necrosis factor/nerve growth factor receptor family inhibits T cell receptor-induced apoptosis.

By comparing untreated and dexamethasone-treated murine T cell hybridoma (3DO) cells by the differential display technique, we have cloned a new gene, GITR (glucocorticoid-induced tumor necrosis factor receptor family-related gene) encoding a new member of the tumor necrosis factor/nerve growth factor receptor family. GITR is a 228-amino acids type I transmembrane protein characterized by three cysteine pseudorepeats in the extracellular domain and similar to CD27 and 4-1BB in the intracellular domain. GITR resulted to be expressed in normal T lymphocytes from thymus, spleen, and lymph nodes, although no expression was detected in other nonlymphoid tissues, including brain, kidney, and liver. Furthermore, GITR expression was induced in T lymphocytes upon activation by anti-CD3 mAb, Con A, or phorbol 12-myristate 13-acetate plus Ca-ionophore treatment. The constitutive expression of a transfected GITR gene induced resistance to anti-CD3 mAb-induced apoptosis, whereas antisense GITR mRNA expression lead to increased sensitivity. The protection toward T cell receptor-induced apoptosis was specific, because other apoptotic signals (Fas triggering, dexamethasone treatment, or UV irradiation) were not modulated by GITR transfection. Thus, GITR is a new member of tumor necrosis factor/nerve growth factor receptor family involved in the regulation of T cell receptor-mediated cell death.