Essential roles of TGF-beta in anti-CD3 antibody therapy: reversal of diabetes in nonobese diabetic mice independent of Foxp3+CD4+ regulatory T cells

Reversal of Experimental Autoimmune Diabetes With an sCD39/Anti-CD3 Treatment

Extracellular (e)ATP, a potent proinflammatory molecule, is released by dying/damaged cells at the site of inflammation and is degraded by the membrane ectonucleotidases CD39 and CD73. In this study, we sought to unveil the role of eATP degradation in autoimmune diabetes. We then assessed the effect of soluble CD39 (sCD39) administration in prevention and reversal studies in NOD mice as well as in mechanistic studies. Our data showed that eATP levels were increased in hyperglycemic NOD mice compared with prediabetic NOD mice. CD39 and CD73 were found expressed by both α- and β-cells and by different subsets of T cells. Importantly, prediabetic NOD mice displayed increased frequencies of CD3+CD73+CD39+ cells within their pancreata, pancreatic lymph nodes, and spleens. The administration of sCD39 into prediabetic NOD mice reduced their eATP levels, abrogated the proliferation of CD4+- and CD8+-autoreactive T cells, and increased the frequency of regulatory T cells, while delaying the onset of T1D. Notably, concomitant administration of sCD39 and anti-CD3 showed a strong synergism in restoring normoglycemia in newly hyperglycemic NOD mice compared with monotherapy with anti-CD3 or with sCD39. The eATP/CD39 pathway plays an important role in the onset of T1D, and its targeting might represent a potential therapeutic strategy in T1D.

ARTICLE HIGHLIGHTS

Reduction of Cell Surface T-Cell Receptor by Non-Mitogenic CD3 Antibody to Mitigate Murine Lupus

T-cells are critically involved in the pathogenesis of systemic lupus erythematosus. Although treatment with the anti-CD3 antibody has been reported to be effective in several autoimmune disease animal models including lupus, the immunosuppressive mechanisms remain obscure because of its pleiotropic in vivo kinetics. In this study, a conventional anti-CD3 (2C11C) and a non-mitogenic anti-CD3 with a manipulated Fc region (2C11S) were compared to elucidate the underlying mechanism of action. The efficacy and safety of 2C11S in vivo were demonstrated by sustained TCR reduction for a longer period as compared to 2C11C and no induction of cytokine release or T-cell depletion. Anti-CD3s were administered to NZB/W F1 (BWF1) mice at different time points for individual periods. The short-term treatment with 2C11S in the early phase of lupus suppressed the autoantibody associated with the reduction of germinal center B-cells. Treatment in the late phase attenuated lupus nephritis without affecting autoantibodies or differentiation of effector T-cells. The effect of reduced TCR in the development of autoimmunity was examined by CD3ζ heterozygous-deficient mice, in which T-cells had reduced TCR intensity but showed normal TCR signaling response. Autoantibody and lupus nephritis were attenuated significantly in CD3ζ heterozygous-deficient lupus-prone mice. Collectively, the reduction of surface TCR by non-mitogenic anti-CD3 could sufficiently suppress the development of lupus.

Involvement of TGF-β and Autophagy Pathways in Pathogenesis of Diabetes: A Comprehensive Review on Biological and Pharmacological Insights

Despite recent advancements in clinical drugs, diabetes treatment still needs further progress. As such, ongoing research has attempted to determine the precise molecular mechanisms of the disorder. Specifically, evidence supports that several signaling pathways play pivotal roles in the development of diabetes. However, the exact molecular mechanisms of diabetes still need to be explored. This study examines exciting new hallmarks for the strict involvement of autophagy and TGF-β signaling pathways in the pathogenesis of diabetes and the design of novel therapeutic strategies. Dysregulated autophagy in pancreatic β cells due to hyperglycemia, oxidative stress, and inflammation is associated with diabetes and accompanied by dysregulated autophagy in insulin target tissues and the progression of diabetic complications. Consequently, several therapeutic agents such as adiponectin, ezetimibe, GABA tea, geniposide, liraglutide, guava extract, and vitamin D were shown to inhibit diabetes and its complications through modulation of the autophagy pathway. Another pathway, TGF-β signaling pathway, appears to play a part in the progression of diabetes, insulin resistance, and autoimmunity in both type 1 and 2 diabetes and complications in diabetes. Subsequently, drugs that target TGF-β signaling, especially naturally derived ones such as resveratrol, puerarin, curcumin, hesperidin, and silymarin, as well as Propolis, Lycopus lucidus, and Momordica charantia extracts, may become promising alternatives to current drugs in diabetes treatment. This review provides keen insights into novel therapeutic strategies for the medical care of diabetes.

Repositioning of the antipsychotic drug TFP for sepsis treatment

Abstract

Sepsis is a disease responsible for the death of almost all critical patients. Once infected by virus or bacteria, patients can die due to systemic inflammation within a short period of time. Cytokine storm plays an essential role in causing organ dysfunction and septic shock. Thus, inhibition of cytokine secretion is considered very important in sepsis therapy. In this study, we found that TFP, an antipsychotic drug mainly used to treat schizophrenia by suppressing dopamine secretion, inhibited cytokine release from activated immune cells both in vitro and in vivo. Trifluoperazine (TFP) decreased the levels of pro-inflammatory cytokines without altering their transcription level. In LPS-induced endotoxemia and cecal content injection (CCI) models, TFP intraperitoneal administration improved survival rate. Thus, TFP was considered to inhibit the secretion of proteins through a mechanism similar to that of W7, a calmodulin inhibitor. Finally, we confirmed that TFP treatment relieved organ damage by estimating the concentrations of aspartate transaminase (AST), alanine transaminase (ALT), and blood urea nitrogen (BUN) in the serum. Our findings were regarded as a new discovery of the function of TFP in treating sepsis patients.

Key messages

• TFP inhibits LPS-induced activation of DCs by suppressing pro-inflammatory cytokine.

• Treatment of TFP increases survival of LPS-induced endotoxemia and CCI sepsis models.

• TFP exerted a protective effect against tissue or organ damage in animal models.

Electronic supplementary material

The online version of this article (10.1007/s00109-019-01762-4) contains supplementary material, which is available to authorized users.

Polysaccharides extracted from the roots of Bupleurum chinense DC modulates macrophage functions

The present study aimed to investigate the effects of polysaccharides extracted from Bupleurum chinense DC (BCPs) on macrophage functions. In the in vivo experiment, 1 mL of 5% sodium thioglycollate was injected into the abdomen of the mice on Day 0 and macrophages were harvested on Day 4. The macrophages were cultured in plates and treated with different concentrations of BCPs and stimulus. Effects of BCPs on macrophage functions were assessed by chemotaxis assay, phagocytosis assay and Enzyme-Linked Immunosorbent Assay (ELISA). Our results showed the enhanced chemotaxis, phagocytosis and secretion of nitric oxide (NO) and inflammatory cytokines by macrophages when treated with BCPs. However, when chemotaxis and phagocytosis were up-regulated by complement components or opsonized particles, BCPs inhibited these effects. Also, the NO production induced by lipopolysaccharides (LPS) was suppressed by BCPs mildly. Moreover, BCPs had an inhibitory effect on the [Ca²⁺]_i elevation of macrophages. These results suggested that BCPs exerted modulatory effects on macrophage functions, which may contribute to developing novel approaches to treating inflammatory diseases.

Heterogeneous CD3 expression levels in differing T cell subsets correlate with the in vivo anti-CD3-mediated T cell modulation

The tolerogenic anti-CD3ε monoclonal Abs (anti-CD3) are promising compounds for the treatment of type 1 diabetes. Anti-CD3 administration induces transient T cell depletion both in preclinical and in clinical studies. Notably, the said depletion mainly affects CD4(+) but not CD8(+) T cells. Moreover, type 1 diabetes reversal in preclinical models is accompanied by the selective expansion of CD4(+)Foxp3(+) T regulatory (Treg) cells, which are fundamental for the long-term maintenance of anti-CD3-mediated tolerance. The mechanisms that lead to this immune-shaping by affecting mainly CD4(+) T effector cells while sparing CD4(+)Foxp3(+) Treg cells have still to be fully elucidated. This study shows that CD3 expression levels differ from one T cell subset to another. CD4(+)Foxp3(-) T cells contain higher amounts of CD3 molecules than do CD4(+)Foxp3(+) and CD8(+) T cells in both mice and humans. The said differences correlate with the anti-CD3-mediated immune resetting that occurs in vivo after anti-CD3 administration in diabetic NOD mice. Additionally, transcriptome analysis demonstrates that CD4(+)Foxp3(+) Treg cells are significantly less responsive than are CD4(+)Foxp3(-) T cells to anti-CD3 treatment at a molecular level. Thus, heterogeneity in CD3 expression seems to confer to the various T cell subsets differing susceptibility to the in vivo tolerogenic anti-CD3-mediated modulation. These data shed new light on the molecular mechanism that underlies anti-CD3-mediated immune resetting and thus may open new opportunities to improve this promising treatment.

Combining MK626, a novel DPP-4 inhibitor, and low-dose monoclonal CD3 antibody for stable remission of new-onset diabetes in mice

Combining immune intervention with therapies that directly influence the functional state of the β-cells is an interesting strategy in type 1 diabetes cure. Dipeptidyl peptidase-4 (DPP-4) inhibitors elevate circulating levels of active incretins, which have been reported to enhance insulin secretion and synthesis, can support β-cell survival and possibly stimulate β-cell proliferation and neogenesis. In the current study, we demonstrate that the DPP-4 inhibitor MK626, which has appropriate pharmacokinetics in mice, preceded by a short-course of low-dose anti-CD3 generated durable diabetes remission in new-onset diabetic non-obese diabetic (NOD) mice. Induction of remission involved recovery of β-cell secretory function with resolution of destructive insulitis and preservation of β-cell volume/mass, along with repair of the islet angioarchitecture via SDF-1- and VEGF-dependent actions. Combination therapy temporarily reduced the CD4-to-CD8 distribution in spleen although not in pancreatic draining lymph nodes (PLN) and increased the proportion of effector/memory T cells as did anti-CD3 alone. In contrast, only combination therapy amplified Foxp3+ regulatory T cells in PLN and locally in pancreas. These findings open new opportunities for the treatment of new-onset type 1 diabetes by introducing DPP-4 inhibitors in human CD3-directed clinical trials.

Anti-TCR therapy combined with fingolimod for reversal of diabetic hyperglycemia by β cell regeneration in the LEW.1AR1-iddm rat model of type 1 diabetes

The therapeutic capacity of an antibody directed against the T cell receptor (anti-TCR) of the TCR/CD3 complex alone or in combination with fingolimod (FTY720) to reverse the diabetic metabolic state through suppression of autoimmunity and stimulation of β cell regeneration was analyzed in the LEW.1AR1-iddm (IDDM) rat, an animal model of human type 1 diabetes. Animals were treated with anti-TCR (0.5 mg/kg body weight for 5 days) monotherapy or in combination with fingolimod (1 mg/kg body weight for 40 days). Metabolic changes and β cell morphology were analyzed before, immediately after, and 60 days after end of therapy. Both therapies were started early after disease manifestation and led to normoglycemia in parallel with an increase of the C-peptide concentration. Combination therapy increased the β cell mass reaching a range of normoglycemic controls, decreased the apoptosis rate fivefold, and increased the proliferation rate threefold. Additionally, at 60 days after therapy, islets were virtually free of T cells, macrophages, and cytokine expression. In contrast, after anti-TCR monotherapy, β cell mass remained low with an activated immune cell infiltrate. A concomitant fivefold increased β cell apoptosis rate resulted in a complete loss of β cells. Only combination therapy yielded sustained normoglycemia with full reversal of islet infiltration and restoration of pancreatic β cell mass.

KEY MESSAGE

Combination therapy of anti-TCR and fingolimod was effective in the reversal of T1D. Combination therapy increased the pancreatic β cell mass to normoglycemic control levels. Combination therapy leads to a full reversal of pancreatic islet infiltration. Anti-TCR monotherapy did not abolish islet infiltration. Combination therapy was successful only immediately after diabetes manifestation.

Differential response of regulatory and conventional CD4⁺ lymphocytes to CD3 engagement: clues to a possible mechanism of anti-CD3 action?

Several clinical trials have shown anti-CD3 treatment to be a promising therapy for autoimmune diabetes, but its mechanism of action remains unclear. Foxp3(+) regulatory T cells (Tregs) are likely to be involved, but through unknown mechanistic pathways. We profiled the transcriptional consequences in CD4(+) Tregs and conventional T cells (Tconvs) in the first hours and days after anti-CD3 treatment of NOD mice. Anti-CD3 treatment led to a transient transcriptional response, terminating faster than most Ag-induced responses. Most transcripts were similarly induced in Tregs and Tconvs, but several were differential, in particular, those encoding the IL-7R and transcription factors Id2/3 and Gfi1, upregulated in Tregs but repressed in Tconvs. Because IL-7R was a plausible candidate for driving the homeostatic response of Tregs to anti-CD3, we tested its relevance by supplementation of anti-CD3 treatment with IL-7/anti-IL-7 complexes. Although ineffective alone, IL-7 significantly improved the rate of remission induced by anti-CD3. Four anti-human CD3 mAbs exhibited the same differential effect on IL-7R expression in human as in mouse cells, suggesting that the mechanism also underlies therapeutic effect in human cells, and perhaps a rationale for testing a combination of anti-CD3 and IL-7 for the treatment of recent-onset human type 1 diabetes. Thus, systems-level analysis of the response to anti-CD3 in the early phase of the treatment demonstrates different responses in Tregs and Tconvs, and provides new leads to a mechanistic understanding of its mechanism of action in reverting recent-onset diabetes.

Testing agents for prevention or reversal of type 1 diabetes in rodents

We report the results of an independent laboratory's tests of novel agents to prevent or reverse type 1 diabetes (T1D) in the non-obese diabetic (NOD) mouse, BioBreeding diabetes prone (BBDP) rat, and multiple autoimmune disease prone (MAD) rat models. Methods were developed to better mimic human clinical trials, including: prescreening, randomization, blinding, and improved glycemic care of the animals. Agents were suggested by the research community in an open call for proposals, and selected for testing by an NIDDK appointed independent review panel. Agents selected for testing to prevent diabetes at later stages of progression in a rodent model were a STAT4 antagonist (DT22669), alpha1 anti-trypsin (Aralast NP), celastrol (a natural product with anti-inflammatory properties), and a Macrophage Inflammatory Factor inhibitor (ISO-092). Agents tested for reversal of established T1D in rodent models were: alpha1 anti-trypsin (Aralast NP), tolerogenic peptides (Tregitopes), and a long-acting formulation of GLP-1 (PGC-GLP-1). None of these agents were seen to prevent or reverse type 1 diabetes, while the positive control interventions were effective: anti-CD3 treatment provided disease reversal in the NOD mouse, dexamethasone prevented T1D induction in the MAD rat, and cyclosporin prevented T1D in the BBDP rat. For some tested agents, details of previous formulation, delivery, or dosing, as well as laboratory procedure, availability of reagents and experimental design, could have impacted our ability to confirm prior reports of efficacy in preclinical animal models. In addition, the testing protocols utilized here provided detection of effects in a range commonly used in placebo controlled clinical trials (for example, 50% effect size), and thus may have been underpowered to observe more limited effects. That said, we believe the results compiled here, showing good control and repeatability, confirm the feasibility of screening diverse test agents in an independent laboratory.

The novel therapeutic effect of phosphoinositide 3-kinase-γ inhibitor AS605240 in autoimmune diabetes

Type 1 diabetes (T1D) remains a major health problem worldwide, with a steadily rising incidence yet no cure. Phosphoinositide 3-kinase-γ (PI3Kγ), a member of a family of lipid kinases expressed primarily in leukocytes, has been the subject of substantial research for its role in inflammatory diseases. However, the role of PI3Kγ inhibition in suppressing autoimmune T1D remains to be explored. We tested the role of the PI3Kγ inhibitor AS605240 in preventing and reversing diabetes in NOD mice and assessed the mechanisms by which this inhibition abrogates T1D. Our data indicate that the PI3Kγ pathway is highly activated in T1D. In NOD mice, we found upregulated expression of phosphorylated Akt (PAkt) in splenocytes. Notably, T regulatory cells (Tregs) showed significantly lower expression of PAkt compared with effector T cells. Inhibition of the PI3Kγ pathway by AS605240 efficiently suppressed effector T cells and induced Treg expansion through the cAMP response element-binding pathway. AS605240 effectively prevented and reversed autoimmune diabetes in NOD mice and suppressed T-cell activation and the production of inflammatory cytokines by autoreactive T cells in vitro and in vivo. These studies demonstrate the key role of the PI3Kγ pathway in determining the balance of Tregs and autoreactive cells regulating autoimmune diabetes.

Tolerance-inducing strategies in islet transplantation

Allogeneic islet transplantation is a promising approach for restoring normoglycemia in type 1 diabetic patients. Current use of immunosuppressive therapies for management of islet transplant recipients can be counterintuitive to islet function and can lead to complications in the long term. The induction of donor-specific tolerance eliminates the dependency on immunosuppression and allows recipients to retain responses to foreign antigens. The mechanisms by which tolerance is achieved involve the deletion of donor-reactive T cells, induction of T-cell anergy, immune deviation, and generation of regulatory T cells. This review will outline the various methods used for inducing donor-specific tolerance in islet transplantation and will highlight the previously unforeseen potential of tissue stromal cells in promoting islet engraftment.

Otelixizumab in the treatment of Type 1 diabetes mellitus

Anti-CD3 antibodies have been demonstrated in both animal and human studies to be able to reverse autoimmune diseases; for example Type 1 diabetes. Not only does treatment with anti-CD3 antibodies result in the removal of pathogenic T cells but evidence suggests that a state of operational tolerance can be induced through the effects on regulatory T cells. The clinical use of anti-CD3 antibodies has been hampered by their safety profile. However, the introduction of humanized, nonmitogenic, aglycosylated anti-CD3 antibodies, such as otelixizumab, and promising results reported in newly-diagnosed patients with Type 1 diabetes, have renewed the interest for these antibodies in the treatment of autoimmune diseases.

Anti-CD3 therapy promotes tolerance by selectively depleting pathogenic cells while preserving regulatory T cells

Monoclonal anti-CD3 Abs have been used clinically for two decades to reverse steroid-resistant acute graft rejection. In autoimmune diabetes, short course treatment with FcR-nonbinding (FNB) anti-CD3 mAb in mice with recent onset of diabetes induces long-term disease remission. Induction of tolerogenic regulatory T cells (Tregs) has been implicated to be one of the mechanisms of action by FNB anti-CD3 mAb in these settings. In this study, we examined the effect of FNB anti-CD3 mAb treatment on the homeostasis of naive, effector, and regulatory T cells in vivo. Anti-CD3 treatment induced a transient systemic rise in the percentage but not absolute number of CD4(+)Foxp3(+) Tregs due to selective depletion of CD4(+)Foxp3(-) conventional T cells. T cell depletion induced by FNB anti-CD3 mAb was independent of the proapoptotic proteins Fas, caspase-3, and Bim and was not inhibited by overexpression of the anti-apoptotic protein, Bcl-2. Tregs were not preferentially expanded and we found no evidence of conversion of conventional T cells into Tregs, suggesting that the pre-existing Tregs are resistant to anti-CD3-induced cell death. Interestingly, expression of the transcription factor Helios, which is expressed by thymus-derived natural Tregs, was increased in Tregs after FNB anti-CD3 mAb treatment, suggesting that the anti-CD3 treatment can alter, and potentially stabilize, Treg function. Taken together, the results suggest that FNB anti-CD3 therapy promotes tolerance by restoring the balance between pathogenic and regulatory T cells.

Anti-CD3 antibody ameliorates experimental autoimmune uveitis by inducing both IL-10 and TGF-β dependent regulatory T cells

Chronic/recurrent autoimmune (idiopathic) uveitis is difficult to treat and they account for approximately 10% of legal blindness in the Western world. As it has been reported that anti-CD3 antibody can enhance T cell regulatory function, we investigated its effects in vivo on experimental autoimmune uveitis (EAU), a model for autoimmune uveitis in humans. B10RIII mice immunized with an uveitogenic peptide were treated with the F(ab')(2) fragment of anti-CD3 mAb either before or at clinical disease onset. Evaluation of EAU and cellular responses showed that disease was inhibited and the activation and expansion of pathogenic T cells selectively reduced, whereas functions of Treg in vivo were enhanced. Moreover, mice treated with anti-CD3 mAb were resistant to a second challenge with antigen and thus protected from recurrence of disease. Our results demonstrate that anti-CD3 mAb is a potent inhibitor of autoimmune uveitis.

Anti-CD3 therapy permits regulatory T cells to surmount T cell receptor-specified peripheral niche constraints

Treatment with anti-CD3 is a promising therapeutic approach for autoimmune diabetes, but its mechanism of action remains unclear. Foxp3⁺ regulatory T (T reg) cells may be involved, but the evidence has been conflicting. We investigated this issue in mice derived from the NOD model, which were engineered so that T reg populations were perturbed, or could be manipulated by acute ablation or transfer. The data highlighted the involvement of Foxp3⁺ cells in anti-CD3 action. Rather than a generic influence on all T reg cells, the therapeutic effect seemed to involve an ∼50–60-fold expansion of previously constrained T reg cell populations; this expansion occurred not through conversion from Foxp3⁻ conventional T (T conv) cells, but from a proliferative expansion. We found that T reg cells are normally constrained by TCR-specific niches in secondary lymphoid organs, and that intraclonal competition restrains their possibility for conversion and expansion in the spleen and lymph nodes, much as niche competition limits their selection in the thymus. The strong perturbations induced by anti-CD3 overcame these niche limitations, in a process dependent on receptors for interleukin-2 (IL-2) and IL-7.

Regulatory T cells and autoimmunity

PURPOSE OF REVIEW

The identification of regulatory T cells (Tregs) as regulators of immunological self-tolerance has stimulated tremendous interest in the field. Over the past 12 months, new studies have added greatly to our understanding of the role of Tregs in autoimmune disease, details of which are presented here.

RECENT FINDINGS

In this review, the mechanism of action of Tregs, their antigen specificity and their frequency and function in different autoimmune diseases is explored. Currently available data on the role of transforming growth factor-beta, the reciprocal relationship between Tregs and Th17 cells, Treg markers, and current therapeutic approaches are evaluated. Other regulatory cells, which have been recently identified to play a significant role in autoimmunity, are described.

SUMMARY

Increasing insights into understanding the complex mechanisms of action of Tregs have already led to exciting therapeutic advances. This review provides an in-depth analysis of recent advances in the field of Tregs in autoimmunity. It highlights targets for future immunomodulatory therapy that may treat and potentially cure autoimmune disease, and it identifies areas for future research.

Anti-CD3 antibodies modulate anti-factor VIII immune responses in hemophilia A mice after factor VIII plasmid-mediated gene therapy

One major obstacle in gene therapy is the generation of immune responses directed against transgene product. Five consecutive anti-CD3 treatments concomitant with factor VIII (FVIII) plasmid injection prevented the formation of inhibitory antibodies against FVIII and achieved persistent, therapeutic levels of FVIII gene expression in treated hemophilia A mice. Repeated plasmid gene transfer is applicable in tolerized mice without eliciting immune responses. Anti-CD3 treatment significantly depleted both CD4+ and CD8+ T cells, whereas increased transforming growth factor-beta levels in plasma and the frequency of both CD4+CD25+FoxP3+ and CD4+CD25-Foxp3+ regulatory T cells in the initial few weeks after treatment. Although prior depletion of CD4+CD25+ cells did not abrogate tolerance induction, adoptive transfer of CD4+ cells from tolerized mice at 6 weeks after treatment protected recipient mice from anti-FVIII immune responses. Anti-CD3-treated mice mounted immune responses against both T-dependent and T-independent neo-antigens, indicating that anti-CD3 did not hamper the immune systems in the long term. Concomitant FVIII plasmid + anti-CD3 treatment induced long-term tolerance specific to FVIII via a mechanism involving the increase in transforming growth factor-beta levels and the generation of adaptive FVIII-specific CD4+Foxp3+ regulatory T cells at the periphery. Furthermore, anti-CD3 can reduce the titers of preexisting anti-FVIII inhibitory antibodies in hemophilia A mice.

Genetic-induced variations in the GAD65 T-cell repertoire governs efficacy of anti-CD3/GAD65 combination therapy in new-onset type 1 diabetes

To enhance efficacy of forthcoming type 1 diabetes (T1D) clinical trials, combination therapies (CTs) are envisaged. In this study, we showed that efficacy of a CT, using anti-CD3 antibody and glutamic acid decarboxylase of 65 kd (GAD65)-expressing plasmid, to reverse new-onset T1D was dependent upon the genetic background. Synergism between both treatments was only observed in the RIP-LCMV-GP but not in the nonobese diabetic (NOD) or RIP-LCMV-NOD models. Efficacy was associated with an expansion of bystander suppressor regulatory T cells (Tregs) recognizing the C-terminal region of GAD65 and secreting interleukin-10 (IL-10), transforming growth factor-beta (TGF-beta), and interferon-gamma (IFN-gamma). In addition, we found that frequency and epitope specificity of GAD65-reactive CD4(+) T cells during antigen priming at diabetes onset and Tregs detected after CT correlated. Consequently, NOD mice harbored significantly lower levels of GAD65-reactive CD4(+) T cells than RIP-LCMV-GP before and after treatment. Our results demonstrate that antigen-specific T cells available at treatment may differ between various major histocompatibility complex (MHC) and genetic backgrounds. These cells play a major role in shaping T-cell responses following antigen-specific immune intervention and determine whether a beneficial Tregs response is generated. Our findings hold important implications to understand and predict the success of antigen-based clinical trials, where responsiveness to immunotherapy might vary from patient to patient.

Natural killer cells modulate overt autoimmunity to homeostasis in nonobese diabetic mice after anti-CD3 F(ab')2 antibody treatment through secreting transforming growth factor-beta

Recently, the anti-CD3 antibody has been shown to be a promising candidate for the efficient treatment of overt autoimmunity. However, the mechanisms underlying this effect remain unclear. Our previous studies demonstrated that natural killer (NK)T cells and transforming growth factor (TGF)-beta were key elements in anti-CD3 F(ab')(2)-mediated re-establishment of glucose homeostasis and restoration of self tolerance to islets in type 1 diabetes. In this report, we further investigate the regulatory pathways involved, especially the cellular source of TGF-beta production. The treatment of new-onset nonobese diabetic mice with anti-CD3 F(ab')(2) resulted in a significant increase in the numbers of NK cells in spleen and pancreatic lymph nodes that secrete TGF-beta. Depletion of this cell population with a specific anti-AsGM1 antibody abrogated anti-CD3 F(ab')(2) therapeutic effects and splenic TGF-beta production. When fractionated from recovered mice after CD3 antibody therapy, these NK cells actively suppressed diabetogenic cell proliferation and prevented the cotransfer of diabetes into nonobese diabetic-severe combined immunodeficient mice in a TGF-beta-dependent manner. In addition, the regulatory NKT cells from remitting mice were capable of causing NK cells to exhibit a TGF-beta-producing phenotype by the secretion of the T helper 2 cytokines interleukins 4 and 10. Overall, these data indicate that NK cells are the main source of TGF-beta production after anti-CD3 F(ab')(2) treatment, which are controlled by a population of T helper 2-like NKT cells.

Non-mitogenic anti-CD3F(ab')2 monoclonal antibody: a novel approach to control herpetic stromal keratitis

PURPOSE

Treatment with anti-CD3 antibody has been shown to ameliorate and reverse an existing immunopathological condition by inducing tolerance. The purpose of this study is to assess the therapeutic potential of non-Fc receptor (FcR) binding anti-CD3 monoclonal antibody (mAb), CD3F(ab')(2), for the treatment of herpes simplex virus (HSV)-induced stromal keratitis (SK).

METHODS

Balb/c and C57BL/6 mice were ocularly infected with HSV-1 strain RE (HSV-1RE). Infected animals were treated with CD3F(ab')(2). Development of SK starting from day 5 postinfection (p.i.), infiltration of inflammatory cells into the corneas and the generation of the immune response were compared with untreated animals using slit-lamp biomicroscopy, flow cytometry, and ELISA.

RESULTS

In vivo administration of CD3F(ab')(2) resulted in significant reduction in the severity and incidence of SK in the infected animals compared to untreated counterparts. Infiltration of fewer pathogenic CD4(+) T cells into the cornea, along with a lower percentage of cells that could be induced to express IFN-gamma, occurred with anti-CD3F(ab')(2) treatment. Similar observations were noted in the secondary lymphoid tissues. Additionally, an increase in the frequency of CD4(+)Foxp3(+) regulatory T cells was noticed in both cornea and lymphoid tissues of treated animals compared to untreated animals. Treatment with CD3F(ab')(2) also reduced the number of SSIEFARL peptide-specific CD8(+)IFN-gamma(+) T cells in the secondary lymphoid tissues. Furthermore, use of this reagent was moderately effective in limiting lesions in mice with established lesions.

CONCLUSIONS

Taken together, these results show that non-FcR binding anti-CD3 treatment could be useful in limiting SK lesions.

Induction of active tolerance and involvement of CD1d-restricted natural killer T cells in anti-CD3 F(ab')2 treatment-reversed new-onset diabetes in nonobese diabetic mice

The application of anti-CD3 F(ab')(2) monoclonal antibodies has recently been expanded to treat established autoimmune diseases, including type 1 diabetes. However, the mechanism underlying their effect remains largely unclear. We report that short-phase administration of anti-CD3 F(ab')(2) antibodies efficiently allowed 80% of new-onset, nonobese diabetic (NOD) mice to significantly regain both normoglycemia and pancreatic beta cell-specific autoantigen (ie, glutamic acid decarboxylase and insulin) tolerance, with both effects lasting more than 40 weeks. The responsible mechanism appears to involve the induction and maintenance of a population of immunoregulatory CD1d-restricted natural killer T (NKT) cells, which were marked by an enhanced Th2 response and secretion of elevated levels of interleukin-10. In vivo neutralization of interleukin-4 and/or interleukin-10 bioactivity abrogated this anti-CD3-mediated effect. Importantly, when the cotransfer of NKT cells from the livers of anti-CD3-treated mice and splenocytes from untreated, acutely diabetic NOD mice was performed in NOD-severe combined immunodeficient mice, the NKT cells were sufficient to either delay or prevent the onset of diabetes compared with controls where only splenocytes were introduced. These data suggest that CD1d-restricted NKT cells may play a critical role in anti-CD3 antibody-induced diabetes remission and the restoration of immune tolerance.