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Jeffrey A Bluestone

Publications and source records attributed to Jeffrey A Bluestone.

At least 37 records · Page 2Linked to original sources
PubMed2005

Expansion of functional endogenous antigen-specific CD4+CD25+ regulatory T cells from nonobese diabetic mice.

CD4+CD25+Foxp3+ regulatory T cells (T(reg)) are critical for controlling autoimmunity. Evidence suggests that T(reg) development, peripheral maintenance, and suppressive function are dependent on Ag specificity. However, there is little direct evidence that the T(reg) responsible for controlling autoimmunity in NOD mice or other natural settings are Ag specific. In fact, some investigators have argued that polyclonal Ag-nonspecific T(reg) are efficient regulators of immunity. Thus, the goal of this study was to identify, expand, and characterize islet Ag-specific T(reg) in NOD mice. Ag-specific T(reg) from NOD mice were efficiently expanded in vitro using IL-2 and beads coated with recombinant islet peptide mimic-MHC class II and anti-CD28 mAb. The expanded Ag-specific T(reg) expressed prototypic surface markers and cytokines. Although activated in an Ag-specific fashion, the expanded T(reg) were capable of bystander suppression both in vitro and in vivo. Importantly, the islet peptide mimic-specific T(reg) were more efficient than polyclonal T(reg) in suppressing autoimmune diabetes. These results provide a direct demonstration of the presence of autoantigen-specific T(reg) in the natural setting that can be applied as therapeutics for organ-specific autoimmunity.

Animals↗
PubMed2005

B7-independent inhibition of T cells by CTLA-4.

CTLA-4 is an inhibitory molecule that regulates T cell expansion and differentiation. CTLA-4 binding to B7-1/B7-2 is believed to be crucial for its inhibitory signal both by competing for CD28 binding to the same ligands and aggregating CTLA-4 to deliver negative signals. In this study, we demonstrate that B7 binding is not essential for CTLA-4 activity. CTLA-4 knockout T cells are hyperresponsive compared with wild-type T cells in B7-free settings. Expression of a B7-nonbinding CTLA-4 mutant inhibited T cell proliferation, cytokine production, and TCR-mediated ERK activation in otherwise CTLA-4-deficient T cells. Finally, transgenic expression of the ligand-nonbinding CTLA-4 mutant delayed the lethal lymphoproliferation observed in CTLA-4-deficient mice. These results suggest that ligand binding is not essential for the CTLA-4 function and supports an essential role for CTLA-4 signaling during T cell activation.

Animals↗
PubMed2005

An important role of CD80/CD86-CTLA-4 signaling during photocarcinogenesis in mice.

Although previous studies have shown that altered B7 costimulation plays a critical role in UV irradiation-induced regulation of immunity, the individual roles of the B7 receptors (CD28 and CTLA-4) or the B7 family members (CD80 and CD86) have not been explored. Thus, we investigated CTLA-4 signaling during photocarcinogenesis of chronically UV-B-exposed mice using an antagonistic anti-CTLA-4 Ab. Anti-CTLA-4-treated mice developed significantly fewer UV-induced tumors. Moreover, anti-CTLA-4 treatment induced long-lasting protective immunity because progressively growing UV tumors inoculated into anti-CTLA-4- and UV-treated mice that had not developed tumors were rejected. Next, we used mice deficient for CD80, CD86, or both in photocarcinogenesis studies to assess the relative contributions of these CTLA-4 ligands. Double-deficient mice showed significantly reduced UV-induced skin tumor development, whereas CD86(-/-) mice produced skin cancer earlier compared with CD80(-/-) and control mice. The growth of UV-induced tumors appears to be controlled by UV-induced suppressor T cells, because CD80(-/-)/CD86(-/-) mice had strongly reduced numbers of UV-induced CD4(+)CD25(+) suppressor T cells. In vitro, CTLA-4 blockade inhibited the suppressor activity of UV-induced CD4(+)CD25(+) T cells, suggesting that reduced photocarcinogenesis might be due to decreased numbers or function of suppressor T cells. Together, these data indicate that blocking CD80/86-CTLA-4 signaling induced immune protection against the development of UV-induced skin tumors. Furthermore, CD86-mediated costimulation appears to play a more critical role in the protection against photocarcinogenesis than CD80.

Animals↗
PubMed2005

Treatment with nonmitogenic anti-CD3 monoclonal antibody induces CD4+ T cell unresponsiveness and functional reversal of established experimental autoimmune encephalomyelitis.

In vivo administration of anti-CD3 Ab induces both immune tolerance and undesirable side-effects resulting from nonspecific proinflammatory cytokine production. In the current study, we investigated the therapeutic potential of two structurally altered forms of the anti-CD3 Ab in ameliorating established experimental autoimmune encephalomyelitis. Administration of either a chimeric (NM-IgG3) or digestion product (NM-F(ab')2) form of the anti-CD3 Ab during established experimental autoimmune encephalomyelitis conferred significant protection from clinical disease progression and was associated with decreased Ag-specific T cell proliferation, cytokine production, and CNS inflammation. Interestingly, while this protection correlated with an increase in the frequency of CD4(+)CD25(+) regulatory T cells, neither prior depletion of regulatory T cells nor anti-TGF-beta treatment abrogated the treatment's efficacy. Importantly, both treatments induced normal levels of intracellular Ca(2+)-flux, but significantly diminished levels of TCR signaling. Consequent to this decreased level of TCR-mediated signaling were alterations in the level of apoptosis and CD4+ T cell trafficking resulting in a profound lymphopenia. Collectively, these results indicate that nonmitogenic anti-CD3 directly induces a state of immune unresponsiveness in primed pathogenic autoreactive effector cells via mechanisms that may involve the induction of T cell tolerance, apoptosis, and/or alterations in cell trafficking.

Animals↗
PubMed2005

Distinct roles of dendritic cells and B cells in Va14Ja18 natural T cell activation in vivo.

Va14Ja18 natural T (iNKT) cells are innate, immunoregulatory lymphocytes that recognize CD1d-restricted lipid Ags such as alpha-galactosylceramide (alpha GalCer). The immunoregulatory functions of iNKT cells are dependent upon either IFN-gamma or IL-4 production by these cells. We hypothesized that alpha GalCer presentation by different CD1d-positive cell types elicits distinct iNKT cell functions. In this study we report that dendritic cells (DC) play a critical role in alpha GalCer-mediated activation of iNKT cells and subsequent transactivation of NK cells. Remarkably, B lymphocytes suppress DC-mediated iNKT and NK cell activation. Nevertheless, alpha GalCer presentation by B cells elicits low IL-4 responses from iNKT cells. This finding is particularly interesting because we demonstrate that NOD DC are defective in eliciting iNKT cell function, but their B cells preferentially activate this T cell subset to secrete low levels of IL-4. Thus, the differential immune outcome based on the type of APC that displays glycolipid Ags in vivo has implications for the design of therapies that harness the immunoregulatory functions of iNKT cells.

Animals↗
PubMed2005

A comprehensive review of interventions in the NOD mouse and implications for translation.

Type 1 diabetes (T1D) animal models such as the nonobese diabetic (NOD) mouse have improved our understanding of disease pathophysiology, but many candidate therapeutics identified therein have failed to prevent/cure human disease. We have performed a comprehensive evaluation of disease-modifying agents tested in the NOD mouse based on treatment timing, duration, study length, and efficacy. Interestingly, some popular tenets regarding NOD interventions were not confirmed: all treatments do not prevent disease, treatment dose and timing strongly influence efficacy, and several therapies have successfully treated overtly diabetic mice. The analysis provides a unique perspective on NOD interventions and suggests that the response of this model to therapeutic interventions can be a useful predictor of the human response as long as careful consideration is given to treatment dose, timing, and protocols; more thorough investigation of these parameters should improve clinical translation.

Animals↗
PubMed2005

Regulatory T-cell therapy: is it ready for the clinic?

The identification of suppressor T cells as important regulators of basic processes that are designed to maintain tolerance has opened an important area of potential clinical investigation in autoimmunity, graft-versus-host disease and transplantation. However, the field has been limited by an inability to define the antigenic specificities of these cells and by the small numbers of circulating regulatory T cells. Recently, new methods for expanding polyclonal and antigen-specific regulatory T cells have emerged. This article summarizes efforts to exploit regulatory T-cell therapy for the treatment of immunological diseases and poses the question of when and where regulatory T cells will first impact on clinical diseases.

Animals↗
PubMed2005

The NOD mouse: a model of immune dysregulation.

Autoimmunity is a complex process that likely results from the summation of multiple defective tolerance mechanisms. The NOD mouse strain is an excellent model of autoimmune disease and an important tool for dissecting tolerance mechanisms. The strength of this mouse strain is that it develops spontaneous autoimmune diabetes, which shares many similarities to autoimmune or type 1a diabetes (T1D) in human subjects, including the presence of pancreas-specific autoantibodies, autoreactive CD4+ and CD8+ T cells, and genetic linkage to disease syntenic to that found in humans. During the past ten years, investigators have used a wide variety of tools to study these mice, including immunological reagents and transgenic and knockout strains; these tools have tremendously enhanced the study of the fundamental disease mechanisms. In addition, investigators have recently developed a number of therapeutic interventions in this animal model that have now been translated into human therapies. In this review, we summarize many of the important features of disease development and progression in the NOD strain, emphasizing the role of central and peripheral tolerance mechanisms that affect diabetes in these mice. The information gained from this highly relevant model of human disease will lead to potential therapies that may alter the development of the disease and its progression in patients with T1D.

Animals↗
PubMed2005

A single course of anti-CD3 monoclonal antibody hOKT3gamma1(Ala-Ala) results in improvement in C-peptide responses and clinical parameters for at least 2 years after onset of type 1 diabetes.

Despite advances in understanding autoimmune diabetes in animal models, there has been little progress in altering the natural course of the human disease, which involves progression to insulin deficiency. Studies with immunosuppressive agents have shown short-term effectiveness, but they have not induced tolerance, and continuous treatment is needed. We studied the effects of hOKT3gamma1(Ala-Ala), a humanized Fc mutated anti-CD3 monoclonal antibody, on the progression of type 1 diabetes in patients with recent-onset disease in a randomized controlled trial. In general, the drug was well tolerated. A single course of treatment, within the first 6 weeks after diagnosis, preserved C-peptide responses to a mixed meal for 1 year after diagnosis (97 +/- 9.6% of response at study entry in drug-treated patients vs. 53 +/- 7.6% in control subjects, P < 0.01), with significant improvement in C-peptide responses to a mixed meal even 2 years after treatment (P < 0.02). The improved C-peptide responses were accompanied by reduced HbA(1c) and insulin requirements. Clinical responses to drug treatment were predicted by an increase in the relative number of CD8(+) T-cells in the peripheral blood after the lymphocyte count recovered 2 weeks after the last dose of drug. We conclude that treatment with the anti-CD3 monoclonal antibody hOKT3gamma1(Ala-Ala) results in improved C-peptide responses and clinical parameters in type 1 diabetes for at least 2 years in the absence of continued immunosuppressive medications.

Adolescent↗
PubMed2004

Therapeutic vaccination using CD4+CD25+ antigen-specific regulatory T cells.

Autoimmune disease results from the dysregulation of basic tolerogenic processes designed to control self/non-self-discrimination. Approaches to treat autoimmunity have focused historically on potent immunosuppressives that block the activation and expansion of antigen-specific T cells before they differentiate into pathogenic T cell responses. These therapies are very efficient in reducing clonal expansion and altering early signaling pathways. However, once the pathogenic responses are established (i.e., autoimmunity), the interventions are less effective on activated and differentiated T cell subsets (including memory T cells) or acting in the presence of an inflammatory milieu to abort immune responses at the target tissue and systemically. Moreover, the current immunotherapies require continuous use because they do not redirect the immune system to a state of tolerance. The continuous treatment leads to long-term toxicities and can profoundly suppress protective immune responses targeted at viruses, bacteria, and other pathogens. Over the past decade, there have been tremendous advances in our understanding of the basic processes that control immune tolerance. Among the most exciting has been the identification of a professional regulatory T cell subset that has shown enormous potential in suppressing pathologic immune responses in autoimmune diseases, transplantation, and graft vs. host disease. In this review, we summarize current efforts to induce and maintain tolerance in the autoimmune diabetes setting by using therapeutic vaccination with CD4(+)CD25(+) regulatory T cells. Emphasis will be placed on approaches to exploit regulatory T cells either directly or through the use of anti-CD3 immunotherapy.

Animals↗
PubMed2004

CTLA-4 regulates expansion and differentiation of Th1 cells following induction of peripheral T cell tolerance.

Intravenous treatment with Ag (peptide)-coupled, ethylene carbodiimide-fixed syngeneic splenocytes (Ag-SP) is a powerful method to induce anergy in vitro and peripheral T cell tolerance in vivo. In this study, we examined the effects of Ag-SP administration on T cell activity ex vivo and in vivo using OVA-specific DO11.10 TCR transgenic T cells. Although treatment with OVA323-339-SP resulted in a strong inhibition of peptide-specific T cell recall responses in vitro, examination of the immediate effects of Ag-SP treatment on T cells in vivo demonstrated that tolerogen injection resulted in rapid T cell activation and proliferation. Although there was an increase in the number of OVA-specific DO11.10 T cells detected in the lymphoid organs, these previously tolerized T cells were strongly inhibited in mounting proliferative or inflammatory responses upon rechallenge in vivo with peptide in CFA. This unresponsiveness was reversible by treatment with anti-CTLA-4 mAb. These results are consistent with the hypothesis that Ag-SP injection induces a state of T cell anergy that is maintained by CTLA-4 engagement.

Adoptive Transfer↗
PubMed2004

In vitro-expanded antigen-specific regulatory T cells suppress autoimmune diabetes.

The low number of CD4+ CD25+ regulatory T cells (Tregs), their anergic phenotype, and diverse antigen specificity present major challenges to harnessing this potent tolerogenic population to treat autoimmunity and transplant rejection. In this study, we describe a robust method to expand antigen-specific Tregs from autoimmune-prone nonobese diabetic mice. Purified CD4+ CD25+ Tregs were expanded up to 200-fold in less than 2 wk in vitro using a combination of anti-CD3, anti-CD28, and interleukin 2. The expanded Tregs express a classical cell surface phenotype and function both in vitro and in vivo to suppress effector T cell functions. Most significantly, small numbers of antigen-specific Tregs can reverse diabetes after disease onset, suggesting a novel approach to cellular immunotherapy for autoimmunity.

Adoptive Transfer↗
PubMed2004

Importance of IL-10 for CTLA-4-mediated inhibition of tumor-eradicating immunity.

In this study, we show that engagement of CTLA-4 on tumor-infiltrating lymphocytes from low-dose melphalan (L-phenylalanine mustard (L-PAM))-treated MOPC-315 tumor bearers led to IL-10 secretion. In addition, the inhibitory activity of CTLA-4 ligation for IFN-gamma secretion following stimulation with anti-CD3 plus anti-CD28 mAb depended on IL-10 production. Consistent with the importance of IL-10 for CTLA-4-mediated inhibition, administration of neutralizing anti-IL-10 mAb to low-dose L-PAM-treated MOPC-315 tumor bearers (administration of blocking anti-CTLA-4 mAb) resulted in enhanced tumor-infiltrating lymphocyte-mediated anti-MOPC-315 cytotoxicity and led to complete tumor eradication in a higher percentage of mice than that observed with low-dose L-PAM alone. The percentage of MOPC-315 tumor-bearing mice cured following administration of neutralizing anti-IL-10 mAb to low-dose L-PAM-treated MOPC-315 tumor bearers was comparable to that observed following administration of blocking anti-CTLA-4 mAb. Moreover, IL-10 neutralization together with CTLA-4 blockade did not provide added therapeutic benefits to low-dose L-PAM-treated MOPC-315 tumor bearers. Taken together, these results indicate that CTLA-4 blockade improves the therapeutic outcome of low-dose L-PAM for MOPC-315 tumor bearers by inhibiting IL-10 secretion as a consequence of blocking CTLA-4 ligation.

Animals↗
PubMed2004

Distinct roles of CTLA-4 and TGF-beta in CD4+CD25+ regulatory T cell function.

Both CTLA-4 and TGF-beta have been implicated in suppression by CD4+CD25+ regulatory T cells (Treg). In this study, the relationship between CTLA-4 and TGF-beta in Treg function was examined. Blocking CTLA-4 on wild-type Treg abrogated their suppressive activity in vitro, whereas neutralizing TGF-beta had no effect, supporting a TGF-beta-independent role for CTLA-4 in Treg-mediated suppression in vitro. In CTLA-4-deficient mice, Treg development and homeostasis was normal. Moreover, Treg from CTLA-4-deficient mice exhibited uncompromised suppressive activity in vitro. These CTLA-4-deficient Treg expressed increased levels of the suppressive cytokines IL-10 and TGF-beta, and in vitro suppression mediated by CTLA-4(-/-) Treg was markedly reduced by neutralizing TGF-beta, suggesting that CTLA-4-deficient Treg develop a compensatory suppressive mechanism through CTLA-4-independent production of TGF-beta. Together, these data suggest that CTLA-4 regulates Treg function by two distinct mechanisms, one during functional development of Treg and the other during the effector phase, when the CTLA-4 signaling pathway is required for suppression. These results help explain contradictions in the literature and support the existence of functionally distinct Treg.

Animals↗
PubMed2004

Peptide specific amelioration of T cell mediated pathogenesis in murine type 1 diabetes.

NOD mice spontaneously develop insulitis and type 1 diabetes (T1D) mellitus similar to humans. Insulitis without overt disease occurs in the BDC2.5 TCR-transgenic NOD mice that express the rearranged TCR alpha- and beta-chain genes of a diabetogenic T cell clone reactive to an unknown beta cell autoantigen. A previous study identified an extensive panel of peptides that are highly active in stimulating T cells from transgenic BDC2.5 mice in culture. However, none of these peptides cause active disease in NOD and BDC2.5 animals or in NOD recipients of adoptively transferred BDC2.5 T cells following direct immunization in vivo. We show that direct immunization of transgenic BDC2.5 mice causes many BDC2.5 T cells to become activated and apoptotic. Strikingly, soluble peptides administered to recipients of activated, highly pathogenic BDC2.5 T cells results in protection from disease. These results suggest that high affinity peptide analogues of autoimmune epitopes might be useful as therapeutic modulators in active autoimmune disease.

Animals↗
PubMed2004

NKG2D blockade prevents autoimmune diabetes in NOD mice.

NKG2D is an activating receptor on CD8(+) T cells and NK cells that has been implicated in immunity against tumors and microbial pathogens. Here we show that RAE-1 is present in prediabetic pancreas islets of NOD mice and that autoreactive CD8(+) T cells infiltrating the pancreas express NKG2D. Treatment with a nondepleting anti-NKG2D monoclonal antibody (mAb) during the prediabetic stage completely prevented disease by impairing the expansion and function of autoreactive CD8(+) T cells. These findings demonstrate that NKG2D is essential for disease progression and suggest a new therapeutic target for autoimmune type I diabetes.

Adoptive Transfer↗
PubMed2004

Notch 1 signaling regulates peripheral T cell activation.

Notch signaling has been identified as an important regulator of leukocyte differentiation and thymic maturation. Less is known about the role of Notch signaling in regulating mature T cells. We examined the role of Notch 1 in regulating peripheral T cell activity in vitro and in vivo. Coligation of Notch 1 together with TCR and CD28 resulted in a dramatic inhibition of T cell activation, proliferation, and cytokine production. This effect was dependent on presenilin activity and induced the expression of HES-1, suggestive of Notch 1 signaling. Biochemical analysis demonstrated an inhibition of AKT and GSK3beta phosphorylation following Notch 1 engagement while other biochemical signals such as TCR and ERK phosphorylation remained intact. Similar effects were observed in vivo in an adoptive transfer model. Therefore, Notch 1 signaling may play an important role in regulating naive T cell activation and homeostasis.

Adoptive Transfer↗