Very low-dose tolerance with nucleosomal peptides controls lupus and induces potent regulatory T cell subsets

Low-dose antigen promotes induction of FOXP3 in human CD4+ T cells

Low Ag dose promotes induction and persistence of regulatory T cells (Tregs) in mice, yet few studies have addressed the role of Ag dose in the induction of adaptive CD4(+)FOXP3(+) Tregs in humans. To this end, we examined the level of FOXP3 expression in human CD4(+)CD25(-) T cells upon activation with autologous APCs and varying doses of peptide. Ag-specific T cells expressing FOXP3 were identified by flow cytometry using MHC class II tetramer (Tmr). We found an inverse relationship between Ag dose and the frequency of FOXP3(+) cells for both foreign Ag-specific and self Ag-specific T cells. Through studies of FOXP3 locus demethylation and helios expression, we determined that variation in the frequency of Tmr(+)FOXP3(+) T cells was not due to expansion of natural Tregs, but instead, we found that induction, proliferation, and persistence of FOXP3(+) cells was similar in high- and low-dose cultures, whereas proliferation of FOXP3(-) T cells was favored in high Ag dose cultures. The frequency of FOXP3(+) cells positively correlated with suppressive function, indicative of adaptive Treg generation. The frequency of FOXP3(+) cells was maintained with IL-2, but not upon restimulation with Ag. Together, these data suggest that low Ag dose favors the transient generation of human Ag-specific adaptive Tregs over the proliferation of Ag-specific FOXP3(-) effector T cells. These adaptive Tregs could function to reduce ongoing inflammatory responses and promote low-dose tolerance in humans, especially when Ag exposure and tolerance is transient.

Novel targets for immunotherapy in glomerulonephritis

Glomerulonephritis is a common cause of chronic kidney disease and end stage renal failure. Current therapy relies on variably effective, nonspecific and toxic immunosuppression. Recent insights into underlying biology and disease pathogenesis in human glomerulonephritis combined with advances in the fields of inflammation and autoimmunity promise a cadre of novel targeted interventions. This review highlights the therapeutic potential of two antigens, alpha3 (IV)NC1 collagen and podocyte neutral endopeptidase, and two cell signaling and effector molecules, IgG Fc receptors and complement, judged to be particularly amenable to therapeutic manipulation in man. It is anticipated that continued dissection of pathogenesis in the diverse disorders that comprise the glomerulonephritides will provide the basis for individualized disease-specific therapy.

Specific immunotherapy and turning off the T cell: how does it work?

OBJECTIVE

To examine T-regulatory (Treg) cell functions in allergic immune responses and their roles during allergen specific immunotherapy based on recent developments and current understanding of immune regulation.

DATA SOURCES

PubMed search of English-language articles regarding Treg cells and allergen specific immunotherapy.

STUDY SELECTION

Articles on the subject matter were selected and reviewed.

RESULTS

Allergen specific immunotherapy is the ultimate treatment modality targeting the immunopathogenic mechanisms of allergic disorders. A diminished allergen-specific T-cell proliferation and suppressed secretion of T(H)1- and T(H)2-type cytokines are the characteristic hallmarks. In addition, Treg cells inhibit the development of allergen-specific T(H)2 and T(H)1 cell responses and therefore exert key roles in healthy immune response to allergens. Treg cells potently suppress IgE production and directly or indirectly control the activity of effector cells of allergic inflammation, such as eosinophils, basophils, and mast cells.

CONCLUSION

As advancements in the field of allergen specific immunotherapy ensue, they may provide novel progression of more rational and safer approaches for the prevention and treatment of allergic disorders. Currently, the Treg cell field is an open research area to increase our understanding in mechanisms of peripheral tolerance to allergens.

IL-17-producing T cells in lupus nephritis

Significant evidence implicates interleukin-17 (IL-17) in the pathogenesis of systemic lupus erythematosus (SLE), particularly in the development of tissue damage. IL-17 production and IL-17-producing CD4+ and CD3 + CD4-CD8- cells are increased in patients with SLE. IL-17-producing cells are present in the inflamed kidney tissues from patients with lupus nephritis. In lupus-prone mice, IL-17 production appears to be involved in the expression of disease pathology and pharmacologic or genetic manipulation of its production results in suppression of the disease. It becomes obvious that the use of biologics including humanized anti-IL-17 antibodies or decoy IL-17 receptors deserve clinical consideration. Similarly, the development of drugs that suppress the production of IL-17 is in order.

Oral administration of different forms of a tolerogenic peptide to define the preparations and doses that delay anti-DNA antibody production and nephritis and prolong survival in SLE-prone mice

Therapeutic agents currently in use to treat systemic lupus erythematosus (SLE) are predominantly immunosuppressive agents with limited specificities. Multiple groups, including ours, have illustrated that inducing tolerance in SLE animal models ameliorates disease symptoms and increases survival. We examined if oral administration of a tolerogenic peptide could affect SLE disease progression. The pConsensus (pCons) peptide, based on protein sequences of anti-double stranded (anti-ds)DNA antibodies, induces tolerance through upregulation of regulatory T cells when administered intravenously. Six different forms of pCons, including multiple antigenic peptides (MAP) and cyclic peptides made up of L- and D-amino acids, at three different concentrations, were fed to BWF1 SLE-susceptible mice for 30 weeks. Mice fed 100 µg of L-MAP or D-MAP had less cumulative proteinuria and serum anti-dsDNA antibody levels than controls. In addition, animals in these groups also survived significantly longer than controls with a corresponding increase in serum transforming growth factor beta (TGFβ, implying a protective role for pCons-induced regulatory T cells. Oral administration of a tolerogenic peptide is a safe, effective method for ameliorating SLE disease manifestations and prolonging survival in SLE-prone mice. Induction of oral tolerance using modified pCons peptides could lead to a novel targeted therapy for human SLE.

Interferon-inducible gene 202b controls CD8(+) T cell-mediated suppression in anti-DNA Ig peptide-treated (NZB × NZW) F1 lupus mice

Administration of an artificial peptide (pConsensus) based on anti-DNA IgG sequences that contain major histocompatibility complex class I and class II T-cell determinants, induces immune tolerance in NZB/NZW F1 female (BWF1) mice. To understand the molecular basis of CD8⁺ Ti-mediated suppression, we previously performed microarray analysis to identify genes that were differentially expressed following tolerance induction with pCons. CD8⁺ T cells from mice tolerized with pCons showed more than two-fold increase in Ifi202b mRNA, an interferon inducible gene, versus cells from untolerized mice. Ifi202b expression increased through weeks 1–4 after tolerization and then decreased, reapproaching baseline levels at 6 weeks. In vitro polyclonal activation of tolerized CD8⁺ T cells significantly increased Ifi202b mRNA expression. Importantly, silencing of Ifi202b abrogated the suppressive capacity of CD8⁺ Ti cells. This was associated with decreased expression of Foxp3, and decreased gene and protein expression of transforming growth factor (TGF)β and interleukin-2 (IL-2), but not of interferon (IFN)-γ, IL-10, or IL-17. Silencing of another IFN-induced gene upregulated in tolerized CD8⁺ T cells, IFNAR1, had no effect on the ability of CD8⁺ T cells to suppress autoantibody production. Our findings indicate a potential role for Ifi202b in the suppressive capacity of peptide-induced regulatory CD8⁺ Ti cells through effects on the expression of Foxp3 and the synthesis of TGFβ.

The histone peptide H4 71-94 alone is more effective than a cocktail of peptide epitopes in controlling lupus: immunoregulatory mechanisms

Tolerance therapy with nucleosomal histone peptides H4(71-94), H4(16-39), or H1'(22-42) controls disease in lupus-prone SNF1 mice. It would be clinically important to determine whether a cocktail of the above epitopes would be superior. Herein, we found that compared with cocktail peptides, H4(71-94) monotherapy more effectively delayed nephritis onset, prolonged lifespan, diminished immunoglobulin G autoantibody levels, reduced autoantigen-specific Th1 and Th17 responses and frequency of T(FH) cells in spleen and the helper ability of autoimmune T cells to B cells, by inducing potent CD8 Treg cells. H4(71-94) therapy was superior in "tolerance spreading," suppressing responses to other autoepitopes, nucleosomes, and ribonucleoprotein. We also developed an in vitro assay for therapeutic peptides (potentially in humans), which showed that H4(71-94), without exogenous transforming growth factor (TGF)-β, was efficient in inducing stable CD4(+)CD25(+)Foxp3(+) T cells by decreasing interleukin 6 and increasing TGF-β production by dendritic cells that induced ALK5-dependent Smad-3 phosphorylation (TGF-β signal) in target autoimmune CD4(+) T cells.

Harnessing regulatory T cells for the therapy of lupus and other autoimmune diseases

Regulatory T cells (Tregs) maintain immunological homeostasis and prevent autoimmunity. The depletion or functional alteration of Tregs may lead to the development of autoimmune diseases. Tregs consist of different subpopulations of cells, of which CD4(+)CD25(+)Foxp3(+) cells are the most well characterized. However, CD8 Tregs also constitute a major cell population that has been shown to play an important role in autoimmune diseases. This review will discuss the role of Tregs in autoimmune diseases in general and specifically in systemic lupus erythematosus (SLE). SLE is a multisystem autoimmune disease characterized by the production of autoantibodies against nuclear components and by the deposition of immune complexes in the kidneys as well as in other organs. Abnormalities in Tregs were reported in SLE patients and in animal models of the disease. Current treatment of SLE is based on immunosuppressive drugs that are nonspecific and may cause adverse effects. Therefore, the development of novel, specific, side effect-free therapeutic means that will induce functional Tregs is a most desirable goal. Our group and others have designed and utilized tolerogenic peptides that ameliorate SLE manifestations in murine models. Here, we demonstrate the role of CD4 and CD8 Tregs, as well as the interaction between the two subsets of cells and the mechanism of action of the tolerogenic peptides. We also discuss their therapeutic potential for the treatment of SLE.

Clearing the complexity: immune complexes and their treatment in lupus nephritis

Systemic lupus erythematosus (SLE) is a classic antibody-mediated systemic autoimmune disease characterised by the development of autoantibodies to ubiquitous self-antigens (such as antinuclear antibodies and antidouble-stranded DNA antibodies) and widespread deposition of immune complexes in affected tissues. Deposition of immune complexes in the kidney results in glomerular damage and occurs in all forms of lupus nephritis. The development of nephritis carries a poor prognosis and high risk of developing end-stage renal failure despite recent therapeutic advances. Here we review the role of DNA-anti-DNA immune complexes in the pathogenesis of lupus nephritis and possible new treatment strategies aimed at their control.

Local induction of immunosuppressive CD8+ T cells in the gut-associated lymphoid tissues

Background

In contrast to intestinal CD4⁺ regulatory T cells (T_regs), the generation and function of immunomodulatory intestinal CD8⁺ T cells is less well defined. To dissect the immunologic mechanisms of CD8⁺ T cell function in the mucosa, reactivity against hemagglutinin (HA) expressed in intestinal epithelial cells of mice bearing a MHC class-I-restricted T-cell-receptor specific for HA was studied.

Methodology and Principal Findings

HA-specific CD8⁺ T cells were isolated from gut-associated tissues and phenotypically and functionally characterized for the expression of Foxp3⁺ and their suppressive capacity. We demonstrate that intestinal HA expression led to peripheral induction of HA-specific CD8⁺Foxp3⁺ T cells. Antigen-experienced CD8⁺ T cells in this transgenic mouse model suppressed the proliferation of CD8⁺ and CD4⁺ T cells in vitro. Gene expression analysis of suppressive HA-specific CD8⁺ T cells revealed a specific up-regulation of CD103, Nrp1, Tnfrsf9 and Pdcd1, molecules also expressed on CD4⁺ T_reg subsets. Finally, gut-associated dendritic cells were able to induce HA-specific CD8⁺Foxp3⁺ T cells.

Conclusion and Significance

We demonstrate that gut specific antigen presentation is sufficient to induce CD8⁺ T_regsin vivo which may maintain intestinal homeostasis by down-modulating effector functions of T cells.

SLE diagnosis and treatment: when early is early

Around 1980 antinuclear antibody testing became widely used in routine laboratory practice leading to a tapering in the lag time between SLE onset and diagnosis. Since then nothing relevant has been introduced which could help us in making the diagnosis of SLE earlier than now. Notably, there is increasing evidence that early diagnosis and treatment could increase SLE remission rate and improve patient prognosis. Although it has been shown that autoantibodies appear before clinical manifestations in SLE patients, currently we cannot predict which autoantibody positive subjects will eventually develop the disease. Thus, great effort should be made in order to identify new biomarkers able to improve our diagnostic potential. B lymphocyte stimulator (BLyS), anti-ribosomal P protein and anti-C1q antibodies are among the most promising. In recent years, some therapeutic options have emerged as appropriate interventions for early SLE treatment, including antimalarials, vitamin D, statins and vaccination with self-derived peptides. All these immune modulators seem to be particularly useful when introduced in an early stage of the disease.

CD8(+) T regulatory/suppressor cells and their relationships with autoreactivity and autoimmunity

Regulatory T lymphocytes (Treg) are fundamental for immune homeostasis since they contribute to the induction of peripheral tolerance to autologous antigens and regulate effector immune responses. Treg subsets are present within both the CD4+and the CD8(+) T cell compartments. Considering the CD8(+) Treg, in the last decades several subpopulations, provided with different phenotypes and mechanisms of action, have been characterized. This review is an attempt of integrating in an organic scenario the different CD8(+) Treg subpopulations. Moreover, it summarizes the findings so far achieved on the existence of CD8(+) Treg alterations in autoimmune diseases.

Therapeutic potential of TGF-β-induced CD4(+) Foxp3(+) regulatory T cells in autoimmune diseases

Foxp3(+) T regulatory cell (Treg) subsets play a crucial role in the maintenance of immune homeostasis against self-antigens. The lack or dysfunction of these cells contributes to the pathogenesis and development of many autoimmune diseases. Therefore, manipulation of these cells may provide a novel therapeutic approach to treat autoimmune diseases. In this review, we provide current opinions concerning the classification, developmental, and functional characterization of Treg subsets. Particular emphasis will be focused on the therapeutic role of TGF-β-induced CD4M(+) Foxp3(+) cells (iTregs) in established autoimmune disease. Moreover, the similarity and diversity of iTregs and naturally occurring, thymus-derived CD4(+) CD25(+) Foxp3(+) regulatory T cells (nTregs) will be discussed, including the finding that the pro-inflammatory cytokine IL-6 can convert nTregs to IL-17-producing cells, whereas iTregs induced by TGF-β are resistant to the effects of this cytokine. Understanding these aspects may help to determine how Tregs can be used in the treatment of autoimmune diseases.

Distinct gene signature revealed in white blood cells, CD4(+) and CD8(+) T cells in (NZBx NZW) F1 lupus mice after tolerization with anti-DNA Ig peptide

Tolerizing mice polygenically predisposed to lupus-like disease (NZB/NZW F1 females) with a peptide mimicking anti-DNA IgG sequences containing MHC class I and class II T cell determinants (pConsensus, pCons) results in protection from full-blown disease attributable in part to the induction of CD4(+)CD25(+)Foxp3+ and CD8(+)Foxp3+ regulatory T cells. We compared 45 000 murine genes in total white blood cells (WBC), CD4(+) T cells, and CD8(+) T cells from splenocytes of (NZBxNZW) F1 lupus-prone mice tolerized with pCons vs untreated naïve mice and found two-fold or greater differential expression for 448 WBC, 174 CD4, and 60 CD8 genes. We identified differentially expressed genes that played roles in the immune response and apoptosis. Using real-time PCR, we validated differential expression of selected genes (IFI202B, Bcl2, Foxp3, Trp-53, CCR7 and IFNar1) in the CD8(+)T cell microarray and determined expression of selected highly upregulated genes in different immune cell subsets. We also determined Smads expression in different immune cell subsets, including CD4(+) T cells and CD8(+) T cells, to detect the effects of TGF-beta, known to be the major cytokine that accounts for the suppressive capacity of CD8(+) Treg in this system. Silencing of anti-apoptotic gene Bcl2 or interferon genes (IFI202b and IFNar1 in combination) in CD8(+) T cells from tolerized mice did not affect the expression of the other selected genes. However, silencing of Foxp3 reduced expression of Foxp3, Ifi202b and PD1-all of which are involved in the suppressive capacity of CD8(+) Treg in this model.

CD8+ Tregs in lupus, autoimmunity, and beyond

While CD4(+)CD25(high) regulatory T cells (Tregs) have garnered much attention for their role in the maintenance of immune homeostasis, recent findings have shown that subsets of CD8(+) T cells (CD8(+) Tregs) display immunoregulatory functions as well. Both CD4(+) Tregs and CD8(+) Tregs appear impaired in number and/or function in several autoimmune diseases and in experimental animal models of autoimmunity, suggesting the possibility of immunotherapeutic targeting of these cells for improved management of autoimmune conditions. Our group has developed a strategy to induce CD8(+) Tregs in autoimmune mice through the use of a tolerogenic self-peptide, and new information has been gained on the phenotype, function and role of induced CD8(+) Tregs in autoimmunity. Here we present an overview of the role and mechanisms of action of CD8(+) Tregs in autoimmunity, with a special focus on lupus. We also discuss the potential role of CD8(+) Tregs in other diseases, including chronic infection and cancer.

Regulatory T cell (Treg) subsets return in patients with refractory lupus following stem cell transplantation, and TGF-beta-producing CD8+ Treg cells are associated with immunological remission of lupus

Compared with conventional drug therapy, autologous hemopoietic stem cell transplantation (HSCT) can induce very-long-term remission in refractory lupus patients. Herein, we show that in posttransplant patients, both CD4(+)CD25(high)FoxP3(+) and an unusual CD8(+)FoxP3(+) Treg subset return to levels seen in normal subjects; accompanied by almost complete inhibition of pathogenic T cell response to critical peptide autoepitopes from histones in nucleosomes, the major lupus autoantigen from apoptotic cells. In addition to a stably sustained elevation of FoxP3, posttransplant CD8 T cells also maintained markedly higher expression levels of latency-associated peptide (LAP), CD103, PD-1, PD-L1, and CTLA-4, as compared with pretransplant CD8 T cells that were identically treated by a one-time activation and rest in short-term culture. The posttransplant CD8 regulatory T cells (Treg) have autoantigen-specific and nonspecific suppressive activity, which is contact independent and predominantly TGF-beta dependent. By contrast, the pretransplant CD8 T cells have helper activity, which is cell contact dependent. Although CD4(+)CD25(high) Treg cells return during clinical remission of conventional drug-treated lupus, the posttransplant patient's CD8 Treg cells are considerably more potent, and they are absent in drug-treated patients in whom CD4 T cell autoreactivity to nucleosomal epitopes persists even during clinical remission. Therefore, unlike conventional drug therapy, hemopoietic stem cell transplantation generates a newly differentiated population of LAP(high)CD103(high) CD8(TGF-beta) Treg cells, which repairs the Treg deficiency in human lupus to maintain patients in true immunological remission.

Dominant role of antigen dose in CD4+Foxp3+ regulatory T cell induction and expansion

The definitions of tolerogenic vs immunogenic dendritic cells (DC) remain controversial. Immature DC have been shown to induce T regulatory cells (Treg) specific for foreign and allogeneic Ags. However, we have previously reported that mature DC (mDC) prevented the onset of autoimmune diabetes, whereas immature DC (iDC) were therapeutically ineffective. In this study, islet-specific CD4(+) T cells from BDC2.5 TCR-transgenic mice were stimulated in the absence of exogenous cytokine with iDC or mDC pulsed with high- or low-affinity antigenic peptides and examined for Treg induction. Both iDC and mDC presenting low peptide doses induced weak TCR signaling via the Akt/mammalian target of rapamycin (mTOR) pathway, resulting in significant expansion of Foxp3(+) Treg. Furthermore, unpulsed mDC, but not iDC, also induced Treg. High peptide doses induced strong Akt/mTOR signaling and favored the expansion of Foxp3(neg) Th cells. The inverse correlation of Foxp3 and Akt/mTOR signaling was also observed in DO11.10 and OT-II TCR-transgenic T cells and was recapitulated with anti-CD3/CD28 stimulation in the absence of DC. IL-6 production in these cultures correlated positively with Ag dose and inversely with Treg expansion. Studies with T cells or DC from IL-6(-/-) mice revealed that IL-6 production by T cells was more important in the inhibition of Treg induction at low Ag doses. These studies indicate that the strength of Akt/mTOR signaling, a critical T cell-intrinsic determinant for Treg vs Th induction, can be controlled by adjusting the dose of antigenic peptide. Furthermore, this operates in a dominant fashion over DC phenotype and cytokine production.

Treating autoimmune disease by targeting CD8(+) T suppressor cells

Current treatments for autoimmune disease are hampered by the non-specificity of immunomodulatory interventions, having to accept broad suppression of immunoresponsiveness with potentially serious side effects, such as infection or malignancy. The development of antigen-specific approaches, downregulating pathogenic immune responses while maintaining protective immunity, would be a major step forward. One possible approach involves the targeting of physiological regulatory mechanisms, such as inhibitory CD8 T cells that are now recognized to fine-tune many aspects of immune responses. CD8 T suppressor (Ts) cells may directly inhibit other T cells or condition antigen-presenting cells in such a way that immune amplification steps are dampened. The promise of CD8 Ts cells lies in their potential to disrupt host-injurious immune responses in a targeted fashion. For therapeutic purposes, such CD8 Ts cells could either be generated in vitro and transferred into the host or their numbers and activity could be modulated by treating the patient with established or novel immunomodulators. Emerging evidence shows that several subsets of CD8 Ts cells exist. While there is still considerable uncertainty about the molecular mechanisms through which CD8 Ts cells can reset immune responses to protect the host, their potential diagnostic and therapeutic use is intriguing and has generated renewed interest.

A new model of induced experimental systemic lupus erythematosus (SLE) in pigs and its amelioration by treatment with a tolerogenic peptide

INTRODUCTION

Systemic lupus erythematosus (SLE) is characterized by a variety of autoantibodies and systemic clinical manifestations. A tolerogenic peptide, hCDR1, ameliorated lupus manifestations in mice models. The objectives of this study were to induce experimental SLE in pigs and to determine the ability of hCDR1 to immunomodulate the disease manifestations.

RESULTS AND DISCUSSION

We report here the successful induction, by a monoclonal anti-DNA antibody, of an SLE-like disease in pigs, manifested by autoantibody production and glomerular immune complex deposits. Treatment of pigs with hCDR1 ameliorated the lupus-related manifestations. Furthermore, the treatment downregulated the gene expression of the pathogenic cytokines, interleukin (IL)-1beta, tumor necrosis factor alpha, interferon gamma, and IL-10, and upregulated the expression of the immunosuppressive cytokine transforming growth factor beta, the antiapoptotic molecule Bcl-xL, and the suppressive master gene, Foxp3, hence restoring the expression of the latter to normal levels. Thus, hCDR1 is capable of ameliorating lupus in large animals and is a potential candidate for the treatment of SLE patients.

Molecular therapies for systemic lupus erythematosus: clinical trials and future prospects

The prognosis of patients with systemic lupus erythematosus has greatly improved since treatment regimens combining corticosteroids and immunosuppressive medications have been widely adopted in therapeutic strategies given to these patients. Immune suppression is evidently efficient but also leads to higher susceptibility to infectious and malignant diseases. Toxic effects and sometimes unexpectedly dramatic complications of current therapies have been progressively reported. Identifying novel molecular targets therefore remains an important issue in the treatment of lupus. The aim of this review article is to highlight emerging pharmacological options and new therapeutic avenues for lupus with a particular focus on non-antibody molecular strategies.

Function and dysfunction of dendritic cells in autoimmune rheumatic diseases

Dendritic cells (DC) have been implicated both in initiation of immunity and in immune tolerance. The mechanisms whereby tolerogenic DC may induce and maintain peripheral tolerance include the generation or expansion of regulatory T cells (Treg) and the promotion of T-cell anergy or deletion. A wide spectrum of hematopoietic growth factors and cytokines are endowed with the ability to differentiate tolerogenic DC both in vitro and in vivo. Based on this knowledge, therapeutic vaccination with cytokine-modulated tolerogenic DC has been applied to animal models of autoimmune disorders. This article will review the current experimental evidence underpinning DC dysfunction in rheumatic autoimmune diseases and will discuss how the manipulation of DC and Treg number and function may control undesired T-cell responses.

Suppression of murine SLE by oral anti-CD3: inducible CD4+CD25-LAP+ regulatory T cells control the expansion of IL-17+ follicular helper T cells

Lupus is an antibody-mediated autoimmune disease. The production of pathogenic, class switched and affinity maturated autoantibodies in lupus is dependent on T cell help. A potential mechanism of disease pathogenesis is a lack of control of pathogenic T helper cells by regulatory T cells in lupus. It has been repeatedly shown that the naturally occurring CD4+CD25+ regulatory T cells in lupus prone mice and patients with SLE are defective both in frequency and function. Thus, the generation of inducible regulatory T cells that can control T cell help for autoantibody production is a potential avenue for the treatment of SLE. We have found that oral administration of anti-CD3 monoclonal antibody attenuated lupus development and arrested on-going disease in lupus prone SNF1 mice. Oral anti-CD3 induces a CD4+CD25-LAP+ regulatory T cell that secrets high levels of TGF-beta and suppresses in vitro in TFG-beta-dependent fashion. Animals treated with oral anti-CD3 had less glomerulonephritis and diminished levels of anti-dsDNA autoantibodies. Oral anti-CD3 led to a downregulation of IL-17+CD4+ICOS-CXCR5+ follicular helper T cells, CD138+ plasma cells and CD73+ mature memory B cells. Our results show that oral anti-CD3 induces CD4+CD25-LAP+ regulatory T cells that suppress lupus in mice and is associated with downregulation of T cell help for autoantibody production.

Potential for anti-DNA immunoglobulin peptide therapy in systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with elevated morbidity and multi-organ involvement. While many strategies have shown efficacy and improved management of SLE, they have often been associated with adverse effects. Some patients may not respond well to some treatments because of inter-individual variability of the disease. More specific and safer therapies are needed.

OBJECTIVE/METHODS

To review literature on peptide-based therapy of SLE.

RESULTS/CONCLUSIONS

Recently, emphasis has been placed on targeting molecules and pathways involved in the inflammatory response in SLE, including the use of immunogenic peptides derived from anti-DNA antibodies. Encouraging data from murine models of SLE have led to tests in initial clinical trials in humans--which have unfortunately not met the primary endpoints. The current challenge is to design improved strategies for immunotherapeutic use of anti-DNA peptides in SLE.

Apigenin, a non-mutagenic dietary flavonoid, suppresses lupus by inhibiting autoantigen presentation for expansion of autoreactive Th1 and Th17 cells

Introduction

Lupus patients need alternatives to steroids and cytotoxic drugs. We recently found that apigenin, a non-mutagenic dietary flavonoid, can sensitize recurrently activated, normal human T cells to apoptosis by inhibiting nuclear factor-kappa-B (NF-κB)-regulated Bcl-x_L, cyclooxygenase 2 (COX-2), and cellular FLICE-like inhibitory protein (c-FLIP) expression. Because sustained immune activation and hyperexpression of COX-2 and c-FLIP contribute to lupus, we treated SNF1 mice that spontaneously develop human lupus-like disease with apigenin.

Methods

SNF1 mice with established lupus-like disease were injected with 20 mg/kg of apigenin daily and then monitored for development of severe nephritis. Histopathologic changes in kidneys, IgG autoantibodies to nuclear autoantigens in serum and in cultures of splenocytes, along with nucleosome-specific T helper 1 (Th1) and Th17 responses, COX-2 expression, and apoptosis of lupus immune cells were analyzed after apigenin treatment.

Results

Apigenin in culture suppressed responses of Th1 and Th17 cells to major lupus autoantigen (nucleosomes) up to 98% and 92%, respectively, and inhibited the ability of lupus B cells to produce IgG class-switched anti-nuclear autoantibodies helped by these Th cells in presence of nucleosomes by up to 82%. Apigenin therapy of SNF1 mice with established lupus suppressed serum levels of pathogenic autoantibodies to nuclear antigens up to 97% and markedly delayed development of severe glomerulonephritis. Apigenin downregulated COX-2 expression in lupus T cells, B cells, and antigen-presenting cells (APCs) and caused their apoptosis. Autoantigen presentation and Th17-inducing cytokine production by dendritic cells were more sensitive to the inhibitory effect of apigenin in culture, as evident at 0.3 to 3 μM, compared with concentrations (10 to 100 μM) required for inducing apoptosis.

Conclusions

Apigenin inhibits autoantigen-presenting and stimulatory functions of APCs necessary for the activation and expansion of autoreactive Th1 and Th17 cells and B cells in lupus. Apigenin also causes apoptosis of hyperactive lupus APCs and T and B cells, probably by inhibiting expression of NF-κB-regulated anti-apoptotic molecules, especially COX-2 and c-FLIP, which are persistently hyperexpressed by lupus immune cells. Increasing the bioavailability of dietary plant-derived COX-2 and NF-κB inhibitors, such as apigenin, could be valuable for suppressing inflammation in lupus and other Th17-mediated diseases like rheumatoid arthritis, Crohn disease, and psoriasis and in prevention of inflammation-based tumors overexpressing COX-2 (colon, breast).

Treatment of lupus patients with a tolerogenic peptide, hCDR1 (Edratide): immunomodulation of gene expression

Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by dysregulation of cytokines, apoptosis, and B- and T-cell functions. The tolerogenic peptide, hCDR1 (Edratide), ameliorated the clinical manifestations of murine lupus via down-regulation of pro-inflammatory cytokines and apoptosis, up-regulation of the immunosuppressive cytokine TGF-beta, and the induction of regulatory T-cells. In the present study, gene expression was determined in peripheral blood mononuclear cells of 9 lupus patients that were treated for 26 weeks with either hCDR1 (five patients), or placebo (four patients). Disease activity was assessed by SLEDAI-2K and the BILAG scores. Treatment with hCDR1 significantly down-regulated the mRNA expression of the pathogenic cytokines IL-1beta, TNF-alpha, IFN-gamma, and IL-10, of BLyS (B-lymphocyte stimulator) and of the pro-apoptotic molecules caspase-3 and caspase-8. In contrast, the treatment up-regulated in vivo gene expression of both TGF-beta and FoxP3. Furthermore, hCDR1 treatment resulted in a significant decrease in SLEDAI-2K (from 8.0+/-2.45 to 4.4+/-1.67; P=0.02) and BILAG (from 8.2+/-2.7 to 3.6+/-2.9; P=0.03) scores. Thus, the tolerogenic peptide hCDR1, immunomodulates, in vivo, the expression of genes that play a role in SLE, consequently restoring the global immune dysregulation of lupus patients. Hence, hCDR1 has a potential role as a novel disease-specific treatment for lupus patients.

Cytokines in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of autoantibodies that can form immune complexes and deposit in tissues, causing inflammation and organ damage. There is evidence that interferons and some interleukins can have an active role in the pathogenesis of SLE and can contribute significantly to the immune imbalance in the disease, whereas the role of some cytokines (such as TNF) is still debated. This review discusses the activity of several cytokines in SLE, their effects on the immune cells in relation to the disease pathogenesis, and the promise and limitations of cytokine-based therapies in clinical trials for lupus patients.

Functional islet-specific Treg can be generated from CD4+CD25- T cells of healthy and type 1 diabetic subjects

CD4(+)CD25(+)FOXP3(+) Treg cells require TCR engagement for suppressive function, thus ensuring that suppression occurs only in the presence of specific antigens; however, to date no studies have addressed the function of self-antigen-specific Treg in humans. These studies were designed to determine whether peripheral generation and function of islet antigen-specific adaptive Treg are defective in human subjects with type 1 diabetes (T1D). Islet antigen-specific adaptive Treg were induced in vitro by activation of CD4(+)FOXP3(-) T cells with glutamic acid decarboxylase and islet-specific glucose-6-phosphate catalytic subunit-related protein peptides in the context of T1D-associated HLA-DRbeta alleles. Antigen-specific Treg were characterized using flow cytometry for FOXP3 and class II tetramer and assessed for the ability to inhibit proliferation. These adaptive Treg were then compared with influenza-specific Treg from the same study population. The function of tetramer(+) cells that expressed FOXP3 was similar for both influenza and islet antigens generated from control and T1D subjects. In fact, the potency of suppression correlated with FOXP3 expression, not antigen specificity. Thus, these data suggest that development of functional adaptive Treg can occur in response to islet antigens and activation of islet-specific Treg may potentially be used as a targeted immunotherapy in T1D.

Spliceosomal peptide P140 for immunotherapy of systemic lupus erythematosus: results of an early phase II clinical trial

OBJECTIVE

To assess the safety, tolerability, and efficacy of spliceosomal peptide P140 (IPP-201101; sequence 131-151 of the U1-70K protein phosphorylated at Ser140), which is recognized by lupus CD4+ T cells, in the treatment of patients with systemic lupus erythematosus (SLE).

METHODS

An open-label, dose-escalation phase II study was conducted in two centers in Bulgaria. Twenty patients (2 male and 18 female) with moderately active SLE received 3 subcutaneous (SC) administrations of a clinical batch of P140 peptide at 2-week intervals. Clinical evaluation was performed using approved scales. A panel of autoantibodies, including antinuclear antibodies, antibodies to extractable nuclear antigens (U1 RNP, SmD1, Ro/SSA, La/SSB), and antibodies to double-stranded DNA (anti-dsDNA), chromatin, cardiolipin, and peptides of the U1-70K protein, was tested by enzyme-linked immunosorbent assay (ELISA). The plasma levels of C-reactive protein, total Ig, IgG, IgG subclasses, IgM, IgA, and IgE, and of the cytokines interleukin-2 and tumor necrosis factor alpha were measured by ELISA and nephelometry.

RESULTS

IgG anti-dsDNA antibody levels decreased by at least 20% in 7 of 10 patients who received 3 x 200 microg IPP-201101 (group 1), but only in 1 patient in the group receiving 3 x 1,000 microg IPP-201101 (group 2). Physician's global assessment of disease activity scores and scores on the SLE Disease Activity Index were significantly decreased in group 1. The changes occurred progressively in the population of responders, increased in magnitude during the treatment period, and were sustained. No clinical or biologic adverse effects were observed in the individuals, except for some local irritation at the highest concentration.

CONCLUSION

IPP-201101 was found to be safe and well tolerated by subjects. Three SC doses of IPP-201101 at 200 microg significantly improved the clinical and biologic status of lupus patients.

Nasal anti-CD3 antibody ameliorates lupus by inducing an IL-10-secreting CD4+ CD25- LAP+ regulatory T cell and is associated with down-regulation of IL-17+ CD4+ ICOS+ CXCR5+ follicular helper T cells

Lupus is an Ab-mediated autoimmune disease. One of the potential contributors to the development of systemic lupus erythematosus is a defect in naturally occurring CD4(+)CD25(+) regulatory T cells. Thus, the generation of inducible regulatory T cells that can control autoantibody responses is a potential avenue for the treatment of systemic lupus erythematosus. We have found that nasal administration of anti-CD3 mAb attenuated lupus development as well as arrested ongoing lupus in two strains of lupus-prone mice. Nasal anti-CD3 induced a CD4(+)CD25(-)latency-associated peptide (LAP)(+) regulatory T cell that secreted high levels of IL-10 and suppressed disease in vivo via IL-10- and TFG-beta-dependent mechanisms. Disease suppression also occurred following adoptive transfer of CD4(+)CD25(-)LAP(+) regulatory T cells from nasal anti-CD3-treated animals to lupus-prone mice. Animals treated with nasal anti-CD3 had less glomerulonephritis and diminished levels of autoantibodies as measured by both ELISA and autoantigen microarrays. Nasal anti-CD3 affected the function of CD4(+)ICOS(+)CXCR5(+) follicular helper T cells that are required for autoantibody production. CD4(+)ICOS(+)CXCR5(+) follicular helper T cells express high levels of IL-17 and IL-21 and these cytokines were down-regulated by nasal anti-CD3. Our results demonstrate that nasal anti-CD3 induces CD4(+)CD25(-)LAP(+) regulatory T cells that suppress lupus in mice and that it is associated with down-regulation of T cell help for autoantibody production.

Antigen-specific tolerogenic and immunomodulatory strategies for the treatment of autoimmune arthritis

OBJECTIVES

To review various antigen-specific tolerogenic and immunomodulatory approaches for arthritis in animal models and patients in regard to their efficacy, mechanisms of action, and limitations.

METHODS

We reviewed the published literature in Medline (PubMed) on the induction of antigen-specific tolerance and its effect on autoimmune arthritis, as well as the recent work on B-cell-mediated tolerance from our laboratory. The prominent key words used in different combinations included arthritis, autoimmunity, immunotherapy, innate immunity, tolerance, treatment, and rheumatoid arthritis (RA). Although this search spanned the years 1975 to 2007, the majority of the short-listed articles belonged to the period 1990 to 2007. The relevant primary as well as cross-referenced articles were then collected from links within PubMed and reviewed.

RESULTS

Antigen-specific tolerance has been successful in the prevention and/or treatment of arthritis in animal models. The administration of soluble native antigen or an altered peptide ligand intravenously, orally, or nasally, and the delivery of the DNA encoding a particular antigen by gene therapy have been the mainstay of immunomodulation. Recently, the methods for in vitro expansion of CD4+CD25+ regulatory T-cells have been optimized. Furthermore, interleukin-17 has emerged as a promising new therapeutic target in arthritis. However, in RA patients, non-antigen-specific therapeutic approaches have been much more successful than antigen-specific tolerogenic regimens.

CONCLUSION

An antigen-specific treatment against autoimmune arthritis is still elusive. However, insights into newly emerging mechanisms of disease pathogenesis provide hope for the development of effective and safe immunotherapeutic strategies in the near future.

Increased Foxp3(+) CD4(+) regulatory T cells with intact suppressive activity but altered cellular localization in murine lupus

Foxp3(+) CD4(+) regulatory T (T(reg)) cells play a pivotal role in the maintenance of dominant self tolerance. Understanding how the failures of immune control by T(reg) cells are involved in autoimmune diseases is important for the development of effective immunotherapies. In the present study, we analyzed the characteristics of endogenous T(reg) cells in (NZB x NZW) F1 (BWF1) mice, a murine model of systemic lupus erythematosus. Unexpectedly, T(reg) number and frequency in aged BWF1 mice with developing lupus nephritis were increased, not decreased, and in vitro suppressive activity in lymphoid organs was intact. In addition, T(reg) cells trafficked to target organs because cells were present in the kidney and lung. T(reg) cells of aged BWF1 mice exhibited altered localization within lymph organs, however, and an altered phenotype, with higher expression levels of chemokine receptors and activation markers, suggesting a highly activated cellular state. Notably, the expression levels of co-stimulatory molecules were also markedly enhanced in the T(reg) cells of aged BWF1 mice. Furthermore, T(reg) cells of BWF1 mice did not show any suppressive effects on antibody production in vitro. Taken together, we conclude that T(reg) cells in BWF1 mice are not predisposed to functional incompetence but rather are present in a highly activated state.

Induction of mucosal tolerance in SLE: a sniff or a sip away from ameliorating lupus?

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by aberrant immune responses against intracellularly derived self antigens. Treatment for SLE relies on the use of aggressive immunosuppressants and steroids that are nonspecific and can cause serious adverse effects. The observation that a systemic immune tolerance to self antigens or generation of regulatory T cells may follow mucosal (nasal or oral) exposure to self proteins or monoclonal antibody against CD3 respectively suggests that induction of mucosal tolerance offers the basis of a side effect-free therapy that could re-establish the ability to distinguish self from non-self and restore peripheral tolerance in individuals susceptible to developing autoimmune diseases. Here I review studies on mucosal tolerance in autoimmune diseases and discuss the therapeutic potential of inducing tolerance for the treatment of SLE.

CD8+ T cells in asthma: friend or foe?

While it is well established that CD4(+) T lymphocytes play a crucial role in the initiation, progression and persistence of asthma, the role of CD8(+) T cells is less understood. CD8(+) T cells form functionally similar subsets which exhibit similar cytokine profiles as Th1 and Th2 cells, known as Tc1 and Tc2. Evidence from animal studies suggest that CD8(+) T cells are capable of regulating IgE production through the induction of IL-12 and IL-18 production in dendritic cells, and that CD8(+) T cells may act to moderate Th2 polarisation within the localised lymph nodes during allergic sensitisation. Such findings have led to the suggestion that Th1 polarising, CD8(+) T cell-inducing vaccines would inhibit the development of airway hyperresponsiveness (AHR) and Th2 cell infiltration. Despite these positive findings, the role of CD8(+) T cells within the lung remains poorly understood. While CD8(+) T cells, particularly those expressing the Tc1 phenotype, are capable of moderating inflammation and suppressing AHR, it has been postulated that Tc2 CD8(+) T cells predominate within established asthma and may act to amplify the inappropriate immune response which defines the condition. Within the clinic, the association between CD8(+) T cells and asthma is almost universally defined as injurious, further suggesting a prejudicial role for these cells within the established disease. CD8(+) T cells may be a valuable potential target for therapeutic intervention, either by potentiating their regulatory effects prior to the development of sensitisation, or through suppressing their pro-inflammatory properties within established atopy.

Upregulation of CD94 on CD8+T cells in anterior chamber-associated immune deviation

BACKGROUND

CD8+ regulatory T cells (Treg) have been considered to be involved in a model of ocular-induced tolerance, known as anterior chamber-associated immune deviation (ACAID). The phenotype and characteristics of CD8+Treg in ACAID remain only poorly understood. Recent studies have reported that the CD94-Qa-1 system is implicated in the induction of ACAID CD8+Treg, but the functions and characteristics of CD8+CD94+T cells remain unclear.

RESULTS

Both mRNA and protein of CD94 and NKG2A were markedly up-regulated on splenic CD8+T cells of ACAID mice compared with controls. Flow cytometric analysis showed that very few CD8+CD94+T cells express granzyme B, perforin and Foxp3. CD8+CD94+T cells, but not CD8+CD94-T cells, magnetically isolated from the spleens of ACAID mice, produced large amounts of TGF-beta1 and exhibited suppressive activity in vitro. Neutralization of TGF-beta1 caused reversal of suppression mediated by CD8+CD94+T cells.

CONCLUSION

CD8+CD94+T cells from ACAID mice exhibited suppressive activity in association with enhanced expression of TGF-beta1, suggesting that CD8+Treg are mainly distributed in CD94+T cell subpopulations.

Induction of immune tolerance by activation of CD8+ T suppressor/regulatory cells in lupus-prone mice

Multiple CD8(+) suppressive T cell (Ts) subtypes are now recognized as essential regulators of the immune system that prevent autoimmunity through secretion of multiple cytokines and the subsequent inhibition of effector lymphocyte function. CD8(+) Ts are an exciting area of study because of the possible therapeutic implications of inducing suppressive cells that are able to subdue or anergize autoimmune manifestations. Current research in systemic lupus erythematosus (SLE), a disease in which most effective therapies are widely immunosuppressive, is often focused on novel and highly targeted ways in which to treat this multiorgan disease. CD8(+) Ts have been impaired in human and murine SLE. Our group and others have utilized tolerogenic peptides to induce and study CD8(+) Ts to understand their function, as well as investigate a possible new SLE therapy. This review will discuss the similarities and differences in CD8(+) Ts subsets, the concept of tolerance as a therapy, and the current understanding of CD8(+) Ts in mouse SLE models.

Inhibitory CD8+ T cells in autoimmune disease

Rheumatologists have long been focused on developing novel immunotherapeutic agents to manage such prototypic autoimmune diseases as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). The ultimate challenge in providing immunosuppressive treatment for patients with RA and SLE has derived from the dilemma that both protective and harmful immune responses result from adaptive immune responses, mediated by highly diverse, antigen-specific T and B cells endowed with powerful effector functions and the ability for long-lasting memory. As regulatory/suppressor T cells can suppress immunity against any antigen, including self-antigens, they emerge as an ideal therapeutic target. Several distinct subtypes of CD8(+) suppressor cells (Ts) have been described that could find application in treating RA or SLE. In a xenograft model of human synovium, CD8(+)CD28(-)CD56(+) T cells effectively suppressed rheumatoid inflammation. Underlying mechanisms involve conditioning of antigen presenting cells (APC). Adoptively transferred CD8(+) T cells characterized by IL-16 secretion have also exhibited disease-inhibitory effects. In mice with polyarthritis, CD8(+) Ts suppressed inflammation by IFNgamma-mediated modulation of the tryptophan metabolism in APC. In SLE animal models, CD8(+) Ts induced by a synthetic peptide exerted suppressive activity mainly via the TGFbeta-Foxp3-PD1 pathway. CD8(+) Ts induced by histone peptides were found to downregulate disease activity by secreting TGFbeta. In essence, disease-specific approaches may be necessary to identify CD8(+) Ts optimally suited to treat immune dysfunctions in different autoimmune syndromes.

Splenic CD8+ T cells secrete TGF-beta1 to exert suppression in mice with anterior chamber-associated immune deviation

Background CD8+ regulatory T cells (Treg) have been considered to be involved in a model of ocular-induced tolerance, known as anterior chamber-associated immune deviation (ACAID). The mechanisms of suppression by CD8+ T cells in ACAID remain only poorly understood. TGF-beta1 is considered as an inhibitory cytokine for immunosuppression in some models. The production of TGF-beta1 by CD8+ T cells in ACAID, and whether CD8+ T cells exert suppression through TGF-beta1, is unknown. Methods The suppressive effect of CD8+ T cells in ACAID mice was determined by a local adoptive transfer (LAT) assay. The production of TGF-beta1 by CD8+ T cells was measured by enzyme-linked immunosorbent assay (ELISA). Anti-TGF-beta1 antibodies were used in the LAT assay to test if they could block the inhibitory effect of CD8+ T cells. Results CD8+ T cells from ACAID mice were shown to block the delayed-type hypersensitivity (DTH) response in an antigen-specific manner in a LAT assay. These CD8+ T cells secreted TGF-beta1, and their suppression could partially be blocked by anti-TGF-beta1 antibodies. Conclusions Our study confirms that CD8+ T cells from ACAID mice possess inhibitory properties. This population exerts part of its suppressive function via the production of TGF-beta1.

T-regulatory cells in systemic lupus erythematosus

Thymus-derived CD4(+)CD25(high)Foxp3(+) T-regulatory cells (Tregs) have an important role in the mechanisms of peripheral immune tolerance and in the prevention of pathogenic autoimmunity through the suppression of proliferation and production of pro-inflammatory cytokines in effector immune cells. Some studies have shown that in systemic lupus erythematosus (SLE) the number of circulating Tregs may be decreased during active disease, and that the extent of such decrease may correlate with severity of the disease. Recent data in murine models of lupus have suggested the possibility to target Tregs for the modulation of SLE, and Treg-based intervention has been proposed as a novel therapeutic mean for a better management of the disease. This review provides an update on the role of Tregs in SLE, discussing new findings in relation to possible targeting of Tregs for immune modulation in lupus.

Neutralizing antibodies to therapeutic enzymes: considerations for testing, prevention and treatment

Lysosomal storage diseases are characterized by deficiencies in lysosomal enzymes, allowing accumulation of target substrate in cells and eventually causing cell death. Enzyme replacement therapy is the principal treatment for most of these diseases. However, these therapies are often complicated by immune responses to the enzymes, blocking efficacy and causing severe adverse outcomes by neutralizing product activity. It is thus crucial to understand the relationships between genetic mutations, endogenous residual enzyme proteins (cross-reactive immunologic material), development of neutralizing antibodies and their impact on clinical outcomes of lysosomal storage diseases. For patients in whom neutralizing antibodies may cause severe adverse clinical outcomes, it is paramount to develop tolerance inducing protocols to preclude, where predictable, or treat such life-threatening responses.

Novel therapeutics for systemic lupus erythematosus

PURPOSE OF REVIEW

This review provides an update on recently explored therapies in systemic lupus erythematosus and introduces novel therapeutic approaches under consideration. Recent advances in our understanding of systemic lupus are highlighted as well, as these must now inform consideration of therapeutics.

RECENT FINDINGS

Many therapeutic strategies have been shown to be beneficial in murine models of lupus. Compounds that inhibit cellular signaling in response to autoantigens or other triggers and protocols that reconstitute the immune repertoire to diminish autoreactivity are now entering clinical trials.

SUMMARY

Requirements for novel approaches in lupus include improved efficacy and lower toxicity than current therapies, with the goal to reduce tissue damage while preserving immunocompetence.

Natural regulatory T cells: number and function are normal in the majority of patients with lupus nephritis

CD4(+) CD25(+) regulatory T cells have been shown to be a vital component of the mechanisms that prevent autoreactivity in mice and also in humans. Previous studies have examined CD4(+) CD25(hi) regulatory T cell frequency and function in patients with systemic lupus erythematosus (SLE) with mixed results. We investigated frequency, phenotype and function in 21 patients with SLE and six with inactive disease. We found no reduction in frequency of the CD25(hi) subset, although active disease was associated with an increased proportion of CD4(+) CD25(+) T cells. When examining function, in the majority of individuals suppression was comparable with controls, although cells isolated from one patient with active disease failed to suppress proliferation. On testing the effect of CD25(hi) depletion on the responses of whole peripheral blood mononuclear cells to nucleosomes we found that, where a response was detectable from patients, depletion augmented interferon-gamma secretion, demonstrating intact suppression of responses implicated in the pathogenesis of SLE. Our results did not confirm an association of failure in CD4(+) CD25(hi) regulatory T cell function or a reduction in their frequency with active disease. Instead, perturbations in the CD4(+) CD25(hi) regulatory T cell population may play a role in disease in only a minority of the patients afflicted by the diverse syndromes of SLE.

pConsensus peptide induces tolerogenic CD8+ T cells in lupus-prone (NZB x NZW)F1 mice by differentially regulating Foxp3 and PD1 molecules

Systemic lupus erythematosus is an autoimmune disease caused primarily by autoantibodies (including IgG anti-DNA) and immune complexes that cause tissue damage. After tolerization with an artificial peptide (pConsensus, pCons) based on murine anti-DNA IgG sequences containing MHC class I and class II T cell determinants, lupus-prone (NZB x NZW)F(1) female (BWF(1)) mice develop regulatory CD4+CD25+ T cells and inhibitory CD8+ T cells, both of which suppress anti-DNA Ig production and immune glomerulonephritis. In the present work, we show that splenocytes from BWF(1) mice treated with pCons had significant expansion of primarily CD8+ T cells. CD4+ T cells and B cells were each directly suppressed by CD8+ T cells from tolerized mice in a contact-independent manner. Both pCons-induced CD8+CD28+ and CD8+CD28- T cells suppressed production of anti-DNA in vitro. Silencing with small interfering RNA of Foxp3 abrogated the suppression mediated by both CD8+ T cell subsets. Additionally, CD8+ T cells from tolerized mice were weakly cytotoxic against syngeneic B cells from old anti-DNA-producing mice, but not from young mice. Importantly, pCons treatment had dual effects on CD8+ suppressor T cells from tolerized mice, increasing the intracellular expression of Foxp3 while decreasing the surface expression of PD1 molecules. Blocking PD1/PDL1 interactions in the CD8+ T cells from tolerized mice reduced their expression of Foxp3 and their ability to suppress CD4+CD25- proliferation. In contrast, blocking PD1/PDL1 in naive T cells increased Foxp3 expression. Our data suggest that tolerization with pCons activates different subsets of inhibitory/cytotoxic CD8+ T cells whose targets are both CD4+CD25- effector T cells and B cells.