Prevention of systemic lupus erythematosus-like disease in (NZBxNZW)F1 mice by treating with CDR1- and CDR3-based peptides of a pathogenic autoantibody

Humanized Mouse Models of Systemic Lupus Erythematosus: Opportunities and Challenges

Animal models have played a crucial role in the understanding of the mechanisms and treatments of human diseases; however, owing to the large differences in genetic background and disease-specific characteristics, animal models cannot fully simulate the occurrence and progression of human diseases. Recently, humanized immune system mice, based on immunodeficient mice, have been developed that allow for the partial reconstruction of the human immune system and mimic the human in vivo microenvironment. Systemic lupus erythematosus (SLE) is a complex disease characterized by the loss of tolerance to autoantigens, overproduction of autoantibodies, and inflammation in multiple organ systems. The detailed immunological events that trigger the onset of clinical manifestations in patients with SLE are still not well known. Two methods have been adopted for the development of humanized SLE mice. They include transferring peripheral blood mononuclear cells from patients with SLE to immunodeficient mice or transferring human hematopoietic stem cells to immunodeficient mice followed by intraperitoneal injection with pristane to induce lupus. However, there are still several challenges to be overcome, such as how to improve the efficiency of reconstruction of the human B cell immune response, how to extend the lifespan and improve the survival rate of mice to extend the observation period, and how to improve the development of standardized commercialized models and use them. In summary, there are opportunities and challenges for the development of humanized mouse models of SLE, which will provide novel strategies for understanding the mechanisms and treatments of SLE.

Downsizing antibodies: Towards complementarity-determining region (CDR)-based peptide mimetics

Monoclonal antibodies emerged as an important therapeutic drug class with remarkable specificity and binding affinity. Nonetheless, these heterotetrameric immunoglobulin proteins come with high manufacturing and therapeutic costs which can take extraordinary proportions, besides other limitations such as their limited in cellulo access imposed by their molecular size (ca. 150 kDa). These drawbacks stimulated the development of downsized functional antibody fragments (ca. 15-50 kDa), together with smaller synthetic peptides (ca. 1-3 kDa) derived from the antibodies' crucial complementarity-determining regions (CDR). Despite the general lack of success in the literal translation of CDR loops in peptide mimetics, rational structure-based and computational approaches have shown their potential for obtaining functional CDR-based peptide mimetics. In this review, we describe the efforts made in the development of antibody and nanobody paratope-derived peptide mimetics with particular focus on the used design strategies, in addition to highlighting the challenges associated with their development.

Contribution of the Commensal Microflora to the Immunological Homeostasis and the Importance of Immune-Related Drug Development for Clinical Applications

Not long ago, self-reactive immune activity was considered as pathological trait. A paradigm shift has now led to the recognition of autoimmune processes as part of natural maintenance of molecular homeostasis. The immune system is assigned further roles beneath the defense against pathogenic organisms. Regarding the humoral immune system, the investigation of natural autoantibodies that are frequently found in healthy individuals has led to further hypotheses involving natural autoimmunity in other processes as the clearing of cellular debris or decrease in inflammatory processes. However, their role and origin have not been entirely clarified, but accumulating evidence links their formation to immune reactions against the gut microbiome. Antibodies targeting highly conserved proteins of the commensal microflora are suggested to show self-reactive properties, following the paradigm of the molecular mimicry. Here, we discuss recent findings, which demonstrate potential links of the commensal microflora to the immunological homeostasis and highlight the possible implications for various diseases. Furthermore, specific components of the immune system, especially antibodies, have become a focus of attention for the medical management of various diseases and provide attractive treatment options in the future. Nevertheless, the development and optimization of such macromolecules still represents a very time-consuming task, shifting the need to more medical agents with simple structural properties and low manufacturing costs. Synthesizing only the biologically active sites of antibodies has become of great interest for the pharmaceutical industry and offers a wide range of therapeutic application areas as it will be discussed in the present review article.

Peptide-Based Vaccination Therapy for Rheumatic Diseases

Rheumatic diseases are extremely heterogeneous diseases with substantial risks of morbidity and mortality, and there is a pressing need in developing more safe and cost-effective treatment strategies. Peptide-based vaccination is a highly desirable strategy in treating noninfection diseases, such as cancer and autoimmune diseases, and has gained increasing attentions. This review is aimed at providing a brief overview of the recent advances in peptide-based vaccination therapy for rheumatic diseases. Tremendous efforts have been made to develop effective peptide-based vaccinations against rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), while studies in other rheumatic diseases are still limited. Peptide-based active vaccination against pathogenic cytokines such as TNF-α and interferon-α (IFN-α) is shown to be promising in treating RA or SLE. Moreover, peptide-based tolerogenic vaccinations also have encouraging results in treating RA or SLE. However, most studies available now have been mainly based on animal models, while evidence from clinical studies is still lacking. The translation of these advances from experimental studies into clinical therapy remains impeded by some obstacles such as species difference in immunity, disease heterogeneity, and lack of safe delivery carriers or adjuvants. Nevertheless, advances in high-throughput technology, bioinformatics, and nanotechnology may help overcome these impediments and facilitate the successful development of peptide-based vaccination therapy for rheumatic diseases.

Innate and humoral recognition of the products of cell death: differential antigenicity and immunogenicity in lupus

While apoptotic debris is believed to constitute the original antigenic insult in lupus (which is characterized by a time-dependent diversification of autoreactivity), whether such debris and autoantibodies specifically recognizing its constituents mediate differential effects on innate and humoral responses in lupus-prone mice is currently unknown. Apoptotic blebs (as opposed to cellular lysate) enhanced preferentially the maturation of dendritic cells (DCs) from bone marrow precursors drawn from lupus-prone mice. Murine, somatically mutated, apoptotic cell-reactive immunoglobulin (Ig)G monoclonal antibodies demonstrated enhanced recognition of DCs and also displayed a prominent lupus strain-specific bias in mediating DC maturation. Further, immunization of such antibodies specifically in lupus-prone mice resulted in widespread humoral autoreactivity; hypergammaglobulinaemia (a hallmark of systemic autoimmunity) was observed, accompanied by enhanced antibody titres to cellular moieties. Induced antibodies recognized antigens distinct from those recognized by the antibodies employed for immunization; in particular, nephritis-associated anti-double stranded (ds) DNA antibodies and neonatal lupus-associated anti-Ro60 antibodies were elicited by a non-dsDNA, non-Ro60 reactive antibody, and Sm was a favoured target. Further, only in lupus-prone mice did such immunization enhance the kinetics of humoral anti-self responses, resulting in the advanced onset of glomerulosclerosis. These studies reveal that preferential innate and humoral recognition of the products of cell death in a lupus milieu influence the indices associated with autoimmune pathology.

Exploring new territory: considering the future

The European League Against Rheumatism (EULAR)'s guidelines for lupus state that mycophenolate mofetil has at least equivalent efficacy to and less toxicity than cyclophosphamide for the short-and medium-term treatment of lupus nephritis but that long-term data are available only for cyclophosphamide. New therapies are needed to reduce toxicity and the need for steroids and to offer the possibility of cure. Therapies under investigation include other immunosuppressive agents, anticellular therapies, drugs that modify cell-cell interactions, (anti-)cytokine therapy, hormone therapy and lupus-specific immunomodulation.

Rituximab has shown promise in patients refractory to conventional immunosuppression, which suggests that targeting B cells may be successful. Other anti-cell therapies include epratuzumab, belimumab and alemtuzumab. Anti-cytokine approaches include tumour necrosis factor alpha blockade with infliximab, anti-interleukin 6-receptor therapy with tocilizumab and interferon-α blockade. As anti-double-stranded DNA antibodies correlate with flares of lupus nephritis, they may represent another therapeutic target – as do monocyte chemoattractant protein-1 and protein kinase CK2. Therapeutic options to prevent damage in lupus nephritis include non-immunosuppressive treatments aimed at reducing cardiovascular risk (such as statins, angiotensin-converting enzyme inhibitors and aspirin).

As was the case with rheumatoid arthritis, a change in therapeutic aims – from survival through prevention of renal failure to induction of remission – may modify outcomes. EULAR's guidelines state that renal biopsy is the best monitor of clinical outcome in lupus nephritis, as immunological tests have limited predictive value. Measurement of urinary mRNA for cytokine and growth factor genes may provide a more sensitive, non-invasive method of monitoring therapeutic response.

BLyS antagonists and peptide tolerance induction

The major impediment to drug development for systemic lupus erythematosus (SLE) is its heterogeneity. The unpredictable manner in which lupus targets different organs at varying intensity makes the study of new drugs and the optimization of their administration extremely difficult. With the advent of novel, targeted biologic agents for SLE, it can be hoped that more strategic, lupus-relevant immune modulation will lead to safer and more effective treatments. Two alternative new approaches to lupus treatment are reviewed. The first involves selective inhibition of a single protein (BLyS), which may play a central role in host defense and in the pathogenesis of SLE. Although this approach is finely targeted to the inhibition of a single protein which is known to be upregulated in SLE patients, the positioning of BLyS at a critical hub in the immune response suggests that more global adverse repercussions on immunity might still occur. The second strategy is the use of peptides designed to specifically induce tolerance in limited autoreactive immune responses. Immune repercussions might, at least in theory, be almost nonexistent with this kind of approach. Concerns that limited induction of tolerance might have equally limited impact on the complex immune disorder of SLE are not borne out in preliminary murine data. Specific development programs are ongoing using both of these strategies and have recently entered human trials.

Novel approaches to the development of targeted therapeutic agents for systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic multisystem disease in which various cell types and immunological pathways are dysregulated. Current therapies for SLE are based mainly on the use of non-specific immunosuppressive drugs that cause serious side effects. There is, therefore, an unmet need for novel therapeutic means with improved efficacy and lower toxicity. Based on recent better understanding of the pathogenesis of SLE, targeted biological therapies are under different stages of development. The latter include B-cell targeted treatments, agents directed against the B lymphocyte stimulator (BLyS), inhibitors of T cell activation as well as cytokine blocking means. Out of the latter, Belimumab was the first drug approved by the FDA for the treatment of SLE patients. In addition to the non-antigen specific agents that may affect the normal immune system as well, SLE-specific therapeutic means are under development. These are synthetic peptides (e.g. pConsensus, nucleosomal peptides, P140 and hCDR1) that are sequences of conserved regions of molecules involved in the pathogenesis of lupus. The peptides are tolerogenic T-cell epitopes that immunomodulate only cell types and pathways that play a role in the pathogenesis of SLE without interfering with normal immune functions. Two of the peptides (P140 and hCDR1) were tested in clinical trials and were reported to be safe and well tolerated. Thus, synthetic peptides are attractive potential means for the specific treatment of lupus patients. In this review we discuss the various biological treatments that have been developed for lupus with a special focus on the tolerogenic peptides.

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.

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.

A tolerogenic peptide down-regulates mature B cells in bone marrow of lupus-afflicted mice by inhibition of interleukin-7, leading to apoptosis

Systemic lupus erythematosus (SLE) is an autoimmune disease mediated by T and B cells. It is characterized by a variety of autoantibodies and systemic clinical manifestations. A tolerogenic peptide, designated hCDR1, ameliorated the serological and clinical manifestations of SLE in both spontaneous and induced models of lupus. In the present study, we evaluated the status of mature B cells in the bone marrow (BM) of SLE-afflicted mice, and determined the effect of treatment with the tolerogenic peptide hCDR1 on these cells. We demonstrate herein that mature B cells of the BM of SLE-afflicted (New Zealand Black x New Zealand White)F(1) mice were largely expanded, and that treatment with hCDR1 down-regulated this population. Moreover, treatment with hCDR1 inhibited the expression of the pathogenic cytokines [interferon-gamma and interleukin (IL)-10], whereas it up-regulated the expression of transforming growth factor-beta in the BM. Treatment with hCDR1 up-regulated the rates of apoptosis of mature B cells. The latter was associated with inhibited expression of the survival Bcl-xL gene and of IL-7 by BM cells. Furthermore, the addition of recombinant IL-7 abrogated the suppressive effects of hCDR1 on Bcl-xL in the BM cells and resulted in elevated levels of apoptosis. Hence, the down-regulated production of IL-7 contributes to the hCDR1-mediated apoptosis of mature B cells in the BM of SLE-afflicted mice.

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.

The role of dendritic cells in the mechanism of action of a peptide that ameliorates lupus in murine models

Systemic lupus erythematosus (SLE) is characterized in its early stages by the expansion of autoreactive T cells that trigger B-cell activation with subsequent multi-organ injury. Dendritic cells (DCs) in lupus were found to display an aberrant phenotype with higher expression of the maturation markers major histocompatibility complex (MHC) class II, CD80 and CD86, as well as higher production of proinflammatory cytokines including interleukin-12 (IL-12), resulting in an increased ability to activate T cells. A peptide (hCDR1) based on the complementarity determining region-1 of an anti-DNA antibody ameliorated SLE in both induced and spontaneous lupus models by downregulating T-cell functions. Our objectives were to determine whether DCs play a role in promoting the beneficial effects of hCDR1. We showed here that treatment with hCDR1 lowered the expression levels of MHC class II, CD80 and CD86 on DCs. The latter effect was associated with downregulation of messenger RNA expression and secretion of IL-12, a cytokine that upregulated T-cell proliferation and interferon-gamma (IFN-gamma) secretion. Moreover, DCs derived from hCDR1-treated mice downregulated proliferation and IFN-gamma secretion by T cells from untreated mice. Upregulation of transforming growth factor-beta (TGF-beta) secretion by T cells, following treatment with hCDR1, resulted in downregulation of IFN-gamma production and contributed to the phenotypic changes and magnitude of IL-12 secretion by DCs. The ameliorating effects of hCDR1 are therefore mediated at least partially by the upregulated secretion of TGF-beta by T cells that contribute to the induction of DCs with immature phenotype and suppressed functions. The resulting DCs further downregulate autoreactive T-cell functions.

Regulatory T cells in systemic lupus erythematosus: past, present and future

Regulatory/suppressor T cells (Tregs) maintain immunologic homeo-stasis and prevent autoimmunity. In this article, past studies and recent studies of Tregs in mouse models for lupus and of human systemic lupus erythematosus are reviewed concentrating on CD4⁺CD25⁺Foxp3⁺ Tregs. These cells consist of thymus-derived, natural Tregs and peripherally induced Tregs that are similar phenotypically and functionally. These Tregs are decreased in young lupus-prone mice, but are present in normal numbers in mice with established disease. In humans, most workers report CD4⁺Tregs are decreased in subjects with active systemic lupus erythematosus, but the cells increase with treatment and clinical improvement. The role of immunogenic and tolerogenic dendritic cells in controlling Tregs is discussed, along with new strategies to normalize Treg function in systemic lupus erythematosus.

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.

A peptide that ameliorates lupus up-regulates the diminished expression of early growth response factors 2 and 3

Expansion of autoreactive T cells and their resistance to anergy was demonstrated in systemic lupus erythematosus (SLE). A pair of transcription factors, early growth response 2 (Egr-2) and 3 (Egr-3), are negative regulators of T cell activation that were shown to be important in anergy. A peptide (designated hCDR1 for human CDR1) based on the CDR-1 of an anti-DNA Ab ameliorated SLE in both induced and spontaneous lupus models. Our objectives were to determine the expression levels of Egr-2 and Egr-3 in autoreactive T cells following immunization with the lupus-inducing anti-DNA Ab that bears a common Id designated 16/6Id and also in a full-blown SLE and to determine the effect of hCDR1 on these transcription factors. We demonstrated diminished expression levels of Egr-2 and Egr-3 mRNA both early after immunization with the 16/6Id and in SLE-afflicted (NZB x NZW)F1 (New Zealand Black and New Zealand White) mice. Furthermore, by down-regulating Akt phosphorylation and up-regulating TGFbeta secretion, treatment with hCDR1 significantly up-regulated Egr-2 and Egr-3 expression. This was associated with an increased expression of the E3 ligase Cbl-b. Inhibition of Akt in T cells of immunized mice decreased, whereas silencing of the Egr-2 and Egr-3 in T cells of hCDR1-treated mice increased IFN-gamma secretion. Thus, hCDR1 down-regulates Akt phosphorylation, which leads to up-regulated expression of T cell Egr-2 and Egr-3, resulting in the inhibition of IFN-gamma secretion that is required for the maintenance of SLE.

Clinical amelioration of murine lupus by a peptide based on the complementarity determining region-1 of an autoantibody and by cyclophosphamide: similarities and differences in the mechanisms of action

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibodies and systemic clinical manifestations. In this study we investigated the beneficial effects on murine lupus accomplished by a peptide based on the sequence of the complementarity-determining region 1 of an anti-DNA autoantibody (hCDR1) when given alone or in combination with cyclophosphamide (CYC), and determined the mechanisms underlying those effects. SLE-afflicted (NZB x NZW) F(1) mice were treated for 12 weeks with injections of hCDR1, CYC or a combination of both drugs. We found that hCDR1 and CYC ameliorated serological and renal manifestations of the diseased mice, down-regulated interferon-gamma and interleukin-10, and up-regulated transforming growth factor-beta. These effects were associated with an increment of naive CD4(+) cells at the expense of the number of CD4(+) cells with the memory/activated phenotype. Further, the number of CD8(+) cells in the diseased mice was increased by the two drugs, resulting in a significant decrease in the CD4 : CD8 ratio. However, whereas the frequency and activity of CD4(+) CD25(+) CD45RB(low) regulatory T cells and the expression of cytotoxic T-lymphocyte antigen 4 (CTLA-4) in CD4(+) cells were up-regulated by hCDR1 treatment, they were minimally affected following treatment with CYC. CTLA-4 played an important role in the activity of the hCDR1-induced CD4(+) CD25(+) cells as manifested by down-regulation of CD28 expression, decrease of activation-induced apoptosis, and modulation of the cytokine profile in CD4(+) CD25(-) cells derived from SLE-afflicted mice. Thus, although the two drugs have similar ameliorative effects, hCDR1 but not CYC elicits regulatory pathways that are of importance for tolerance induction in SLE.

The negative regulators Foxj1 and Foxo3a are up-regulated by a peptide that inhibits systemic lupus erythematosus-associated T cell responses

A peptide (hCDR1) based on the complementarity determining region-1 of an anti-DNA antibody ameliorates systemic lupus erythematosus (SLE) in induced and spontaneous lupus models. Our objectives were to determine the effects of hCDR1 on TCR signaling and on its negative regulators, Foxj1 and Foxo3a. BALB/c mice were immunized with the SLE-inducing anti-DNA antibody, designated 16/6Id, and treated with hCDR1. hCDR1 treatment specifically inhibited IFN-gamma secretion by T cells in association with down-regulated T-bet expression and NF-kappaB activation; however, GATA-3 expression was not affected. Furthermore, TCR signaling (ZAP-70 phosphorylation) was inhibited, and the mRNA expression of the two modulators of Th1 activation, Foxj1 and Foxo3a, was significantly up-regulated. The latter were also elevated in SLE-afflicted (NZBxNZW)F1 mice that were treated with hCDR1. Addition of TGF-beta, which was elevated following treatment with hCDR1, to T cells from 16/6Id immunized mice, up-regulated Foxj1 and Foxo3a mRNA expression, similarly to hCDR1. In contrast, anti-TGF-beta antibodies added to hCDR1-treated T cells abrogated its effect. Thus, hCDR1 elevates TGF-beta, which contributes to the up-regulation of T cell Foxj1 and Foxo3a expression, leading to inhibition of NF-kappaB activation and IFN-gamma secretion, which is required for the maintenance of SLE.

Regulatory T cells in lupus

Naturally occurring, CD4+ CD25+ regulatory T cells that are exported from the thymus early in life play an important role in controlling organ-specific autoimmune diseases, but they may not be critical for suppressing systemic autoimmunity in lupus. On the other hand, lupus-prone subjects appear to be deficient in generation of adaptive T-regulatory cells that can be induced by various means. We review autoantigen-specific therapeutic approaches that induce such regulatory T cells. Of particular interest are TGF-ss producing CD4+ CD25+ and CD8+ regulatory T cells that are induced by low dose tolerance therapy of lupus-prone mice with nucleosomal histone peptide epitopes, administered subcutaneously in subnanomolar doses. These regulatory T cells are not only efficient in suppressing autoantigen recognition and autoantibody production, but they also inhibit migration/accumulation of pathogenic autoimmune cells in the target organ, such as the kidneys of mice prone to develop lupus nephritis. We discuss why and under what conditions such therapeutic approaches would be beneficial in lupus patients and lupus-prone subjects.

Amelioration of murine lupus by a peptide, based on the complementarity determining region-1 of an autoantibody as compared to dexamethasone: Different effects on cytokines and apoptosis

A peptide (hCDR1) based on the sequence of the complementarity-determining region-1 of an anti-DNA autoantibody ameliorates clinical manifestations of lupus. We analyzed the beneficial effects of hCDR1 when given alone or in combination with dexamethasone, while comparing the mechanisms of action of the latter. Treatment with either hCDR1 or dexamethasone, or a combination of the latter significantly reduced titers of dsDNA-specific autoantibodies, levels of proteinuria, and intensity of glomerular immune complex deposits. Both drugs down-regulated the secretion and expression of IFN-gamma and IL-10, but only treatment with hCDR1 up-regulated TGF-beta. While both drugs reduced the expression of Fas ligand (FasL) and caspase 8, treatment with hCDR1 resulted in reduced whereas dexamethasone administration resulted in increased rate of apoptosis. Furthermore, down-regulation of FasL appeared to play a role in cytokine modulation. We conclude that specific treatment with hCDR1 ameliorates murine lupus via distinct mechanisms of action than those of dexamethasone.

The inhibition of autoreactive T cell functions by a peptide based on the CDR1 of an anti-DNA autoantibody is via TGF-beta-mediated suppression of LFA-1 and CD44 expression and function

Systemic lupus erythematosus (SLE), which is characterized by the increased production of autoantibodies and defective T cell responses, can be induced in mice by immunization with a human anti-DNA mAb that expresses a major Id, designated 16/6Id. A peptide based on the sequence of the CDR1 of the 16/6Id (human CDR1 (hCDR1)) ameliorated the clinical manifestations of SLE and down-regulated, ex vivo, the 16/6Id-induced T cell proliferation. In this study, we examined the mechanism responsible for the hCDR1-induced modulation of T cell functions related to the pathogenesis of SLE. We found that injection of hCDR1 into BALB/c mice concomitant with their immunization with 16/6Id resulted in a marked elevation of TGF-beta secretion 10 days later. Addition of TGF-beta suppressed the 16/6Id-stimulated T cell proliferation similarly to hCDR1. In addition, we provide evidence that one possible mechanism underlying the hCDR1- and TGFbeta-induced inhibition of T cell proliferation is by down-regulating the expression, and therefore the functions, of a pair of key cell adhesion receptors, LFA-1 (alphaLbeta2) and CD44, which operate as accessory molecules in mediating APC-T cell interactions. Indeed, T cells of mice treated with hCDR1 showed a TGF-beta-induced suppression of adhesion to the LFA-1 and CD44 ligands, hyaluronic acid and ICAM-1, respectively, induced by stromal cell-derived factor-1alpha and PMA. The latter suppression is through the inhibition of ERK phosphorylation. Thus, the down-regulation of SLE-associated responses by hCDR1 treatment may be due to the effect of the up-regulated TGF-beta on the expression and function of T cell adhesion receptors and, consequently, on T cell stimulation, adhesion, and proliferation.

Manipulation of immune regulation in systemic lupus erythematosus

Production of autoantibodies by B cells in systemic lupus erythematosus (SLE) can be interrupted via induction of regulatory and suppressor T cells. We have used the strategy of tolerizing lupus-prone (NZBxNZW)F(1) mice with an artificial peptide based on sequences common to several anti-double stranded (ds)DNA antibodies to induce regulatory and suppressor T cells that block production of anti-DNA antibodies and prolong their survival. At least one type of suppressor T cells (CD8+) and one type of regulatory T cell (CD4+ expressing the IL-2 receptor alpha chain CD25) are raised under this condition. While CD8+ suppressors (TS) require soluble factors to block help of T cells to B cells, regulatory CD4+CD25+ T cells (TR) curb the production of anti-DNA antibodies from B cells via cell contact through molecules that include membrane-bound TGFbeta and GITR. Moreover, CD8+ suppressors seem to act independently on antigen specificity, while TR act in an antigen-specific fashion. We hypothesize that the differences between these two lymphocyte subsets that share the common ability to dampen production of autoantibodies might underlie significant temporal and teleological advantages for optimal control of autoimmune reactivity.

Tolerogenic treatment of lupus mice with consensus peptide induces Foxp3-expressing, apoptosis-resistant, TGFbeta-secreting CD8+ T cell suppressors

Lupus-prone (NZB x NZW)F1 mice spontaneously develop elevated titers of anti-DNA Abs that contain T cell determinants in their V(H) regions. We have previously shown that tolerization with an artificial peptide based on these T cell determinants (pConsensus (pCons)) can block production of anti-DNA Abs and prolong survival of the mice. In this study, we show that this protection depends in part on the generation of peripheral TGFbeta- and Foxp3-expressing inhibitory CD8+ (Ti) cells. These CD8+ Ti cells suppress anti-DNA IgG production both in vitro and in vivo and require up-regulated expression of both Foxp3 and TGFbeta to exert their suppressive function, as indicated by microarray analyses, small interfering RNA inhibition studies, and blocking experiments. Additionally, CD8+ Ti cells from pCons-tolerized mice were longer-lived suppressors that up-regulated expression of Bcl-2 and were more resistant to apoptosis than similar cells from naive mice. These data indicate that clinical suppression of autoimmunity after administration of pCons depends in part on the generation of CD8+ Ti cells that suppress secretion of anti-DNA Ig using mechanisms that include Foxp3, TGFbeta, and resistance to apoptosis.

Amelioration of SLE-like manifestations in (NZBxNZW)F1 mice following treatment with a peptide based on the complementarity determining region 1 of an autoantibody is associated with a down-regulation of apoptosis and of the pro-apoptotic factor JNK kinase

Treatment with peptides based on the complementarity determining regions (CDR) of murine and human monoclonal anti-DNA antibodies that bear the common idiotype, 16/6 Id, ameliorates disease manifestations of mice with either induced or spontaneous SLE. Aberrant expression and function of the p21Ras/MAP kinase pathway are associated with active SLE. Therefore, we examined the effect of treatment with a CDR1-based peptide of a human autoantibody (hCDR1) on the p21Ras pathway and SLE manifestations of SLE-prone (NZBxNZW)F1 mice. Untreated SLE-afflicted mice demonstrated increased expression of p21Ras and the phosphorylated active form of its down-stream element JNK kinase in conjunction with reduced hSOS and unchanged p120GAP, as compared to healthy controls. Amelioration of SLE manifestations following treatment with hCDR1 was associated with a diminished expression of phosphorylated JNK kinase, mainly in the T cell population that also exhibited reduced rates of apoptosis. Thus, hCDR1 therapy ameliorates SLE, at least in part, via down-regulation of the activity of the pro-apoptotic JNK kinase.

A peptide based on the complementarity determining region 1 of a human monoclonal autoantibody ameliorates spontaneous and induced lupus manifestations in correlation with cytokine immunomodulation

A peptide based on the sequence of the complementarity determining region (CDR) 1 of a human monoclonal anti-DNA autoantibody that bears the 16/6 idiotype (16/6Id) was synthesized as a potential candidate for the treatment of SLE patients. The peptide, designated hCDR1, did not induce experimental SLE upon active immunization of mice. The ability of the peptide to treat an already established lupus that was either induced in BALB/c mice or developed spontaneously in (NZB x NZW)F1 mice was tested. Ten weekly injections of hCDR1 (200, 50 microg/mouse) given subcutaneously mitigated disease manifestations (e.g., leukopenia, proteinuria and kidney damage) and resulted in a prominent reduction in the dsDNA specific antibody titers. Furthermore, treatment with hCDR1 resulted in reduced secretion and expression of the "pathogenic" cytokines [i.e., INFgamma, IL-1beta, TNFalpha (in the induced model) and IL-10], whereas the immunosuppressive cytokine TGFbeta was up-regulated. Thus, the significant ameliorating effects of hCDR1 are manifested at least partially via the immunomodulation of the cytokine profile. These results suggest that hCDR1 is a potential candidate for a novel treatment of SLE patients.

Down-regulation of stromal cell-derived factor-1alpha-induced T cell chemotaxis by a peptide based on the complementarity-determining region 1 of an anti-DNA autoantibody via up-regulation of TGF-beta secretion

Systemic lupus erythematosus (SLE) can be induced in mice by immunizing them with a monoclonal human anti-DNA Ab that expresses a major Id, designated 16/6Id. In addition, a peptide based on the sequence of the CDR 1 (hCDR1) of the 16/6Id ameliorated the clinical manifestations of SLE in experimental models. In this study we examined the effects of treating mice with human complementary-determining region 1 (hCDR1) on the subsequent chemotaxis of T cells derived from 16/6Id-primed mice. First we demonstrated elevated levels of stromal cell-derived factor-1alpha (SDF-1alpha) in the sera of SLE-afflicted mice and in the sera and lymphoid tissues of 16/6Id-immunized BALB/c mice shortly after the immunization. We then found that administration of hCDR1 to 16/6Id-immunized mice specifically down-regulated SDF1alpha-induced T cell chemotaxis through fibronectin and collagen type I. This was accompanied by diminished SDF1-alpha-induced T cell adhesion and ERK phosphorylation. Treatment with hCDR1 up-regulated TGF-beta secretion, which, in turn, inhibited the murine T cell adhesion to and chemotaxis through fibronectin as well as their ERK phosphorylation. Thus, the secretion of TGF-beta after treatment of 16/6Id-immunized mice with hCDR1 plays an important role in the down-regulation of SDF-1alpha-mediated T cell activation and the interactions with extracellular matrix moieties observed in the present study.

Amelioration of lupus manifestations by a peptide based on the complementarity determining region 1 of an autoantibody in severe combined immunodeficient (SCID) mice engrafted with peripheral blood lymphocytes of systemic lupus erythematosus (SLE) patients

A peptide based on the complementarity determining region (CDR)1 of a human monoclonal anti-DNA autoantibody (hCDR1) was shown to either prevent or treat an already established murine lupus in systemic lupus erythematosus (SLE)-prone mice or in mice with induced experimental SLE. The present study was undertaken to determine the therapeutic potential of hCDR1 in a model of lupus in severe combined immunodeficient (SCID) mice engrafted with peripheral blood lymphocytes (PBL) of patients with SLE. To this end, PBL obtained from lupus patients were injected intraperitoneally into two equal groups of SCID mice that were treated either with the hCDR1 (50 micro g/mouse) once a week for 8 weeks, or with a control peptide. Mice were tested for human IgG levels, anti-dsDNA autoantibodies, anti-tetanus toxoid antibodies and proteinuria. At sacrifice, the kidneys of the successfully engrafted mice were assessed for human IgG and murine complement C3 deposits. Of the 58 mice transplanted with PBL of SLE patients, 38 (66%) were engrafted successfully. The mice that were treated with the control peptide developed human dsDNA-specific antibodies. Treatment with hCDR1 down-regulated the latter significantly. No significant effect of the treatment on the levels of anti-tetanus toxoid antibodies could be observed. Treatment with hCDR1 resulted in a significant amelioration of the clinical features manifested by proteinuria, human IgG complex deposits as well as deposits of murine complement C3. Thus, the hCDR1 peptide is a potential candidate for a novel specific treatment of SLE patients.

Peptide-based immunotherapy of systemic lupus erythematosus

Current drug-based therapy for systemic lupus erythematosus (SLE) are non-specific and often counterbalanced by adverse effects. Current research aims at developing specific treatments that target deleterious cells only and not the whole immune system. This strategy requires the identification of sequences derived from major lupus autoantigens, responsible for the activation of autoreactive B and T cells. This review summarizes the identification and characterization of peptides, which are able to modulate T cells ex vivo, and describes the promising results obtained after administration of some of these peptides in lupus mice. Although these therapeutic trials are encouraging, the precise mode of action of peptide-based immunotherapy is still elusive. Here, we discuss the possible mechanisms leading to T-cell tolerance induction and the feasibility of extending the success of peptide-based therapy from animal models to human.

The role of VH determinants in systemic lupus erythematosus

The V-regions of anti-DNA antibodies contain determinants which can drive the autoimmune in SLE. Most of the evidence comes from murine studies where VH-derived epitopes accelerate the disease process in lupus prone-mice and can elicit mild inflammatory changes reminiscent of lupus in healthy animals. T helper cells reactive with VH peptides arise spontaneously during the disease and are thought to assist production of both anti-peptide antibodies and the generation of autoantibodies that deposit in the glomeruli. In mice stimulatory epitopes may be unique to autoantibodies. As tolerogens VH peptides may delay or diminish the autoimmune response by altering the production of cytokines. An artificial VH peptide, (pCONCENSUS) has been derived and this inhibits responses to VH and other autoantigens but leaves the murine immune system intact and able to generate reponses to external antigens. Limited number of studies of V-region determinants of human anti-DNA MAbs indicate prior sensitization of lupus T cells to VH determinants and that V-region reactive T cells are not deleted in periphery of healthy individuals.

Lupus manifestations in severe combined immunodeficient (SCID) mice and in human/mouse radiation chimeras

The objective of this study was to develop a human lupus model. To this end we have established and compared two models: (1) severe combined immunodeficient (SCID) mice reconstituted with peripheral blood lymphocytes (PBL) of either systemic lupus erythematosus (SLE) patients or healthy controls and (2) lethally irradiated BALB/c mice radioprotected with bone marrow of SCID mice, to which human PBL were transferred (human/mouse chimera). Engraftment was successful in most (78.4%) recipient mice as determined by the levels of human IgG measured. In about 50% of either SCID mice or human/mouse chimeras that were successfully engrafted with PBL of SLE patients, significant anti-dsDNA autoantibodies, mostly of the IgG1 and IgG2 isotypes, were determined. Interestingly, in a significant number (84.5%) of recipients of PBL of the healthy controls, anti-dsDNA antibodies were observed as well, suggesting that PBL of at least some of the healthy controls have the potential to develop SLE-associated autoantibodies under the appropriate stimulatory conditions. Glomerular immune deposits (human IgG, mouse C3) were detected in 70-80% of SCID mice with human DNA specific antibodies and in a third of the human/mouse chimeras. Thus, SLE serology and glomerular pathology were reproducibly demonstrated in two models of human SLE. These models should allow the evaluation of potential therapies for the treatment of lupus patients.

Modulation of autoreactive responses of peripheral blood lymphocytes of patients with systemic lupus erythematosus by peptides based on human and murine anti-DNA autoantibodies

Two peptides, based on the sequences of the complementarity-determining regions (CDR) 1 and 3 of a pathogenic murine monoclonal anti-DNA autoatibody that bears the 16/6 idiotype (Id), were shown to either prevent or treat an already established systemic lupus erythematosus (SLE) in two murine models of lupus. Two additional peptides based on the human monoclonal anti-DNA, 16/6 Id were synthesized. This study was undertaken in order to investigate the ability of the CDR-based peptides to immunomodulate SLE-associated responses of peripheral blood lymphocytes (PBL) of SLE patients. PBL of 24 of the 62 SLE patients tested proliferated in vitro following stimulation with the human 16/6 Id. Peptides based on the CDRs of both the human and murine anti-DNA autoantibodies inhibited efficiently and specifically the 16/6 Id-induced proliferation and IL-2 production. The latter inhibitions correlated with an up-regulated production (by 2.5-3.5-fold) of the immunosuppressive cytokine, TGF-beta. Overall, the results of our study demonstrate that the CDR-based peptides are capable of down-regulating in vitro autoreactive T cell responses of PBL of SLE patients. Thus, these peptides are potential candidates for a novel specific treatment of SLE patients.

Vaccination with minigenes encoding V(H)-derived major histocompatibility complex class I-binding epitopes activates cytotoxic T cells that ablate autoantibody-producing B cells and inhibit lupus

Current treatments for autoantibody-mediated diseases, such as lupus, can cause nonspecific immune suppression. In this paper, we used a bioinformatic approach to identify major histocompatibility complex class I-binding epitopes in the heavy chain variable region of anti-DNA antibodies from lupus-prone (NZB/NZW F1) mice. Vaccination of such mice with plasmid DNA vectors encoding these epitopes induced CD8(+) T cells that killed anti-DNA antibody-producing B cells, reduced serum anti-DNA antibody levels, retarded the development of nephritis, and improved survival. Vaccine-mediated induction of anti-V(H) cytotoxic T lymphocytes that ablate autoreactive B cells represents a novel approach to treat autoantibody-mediated diseases.

Induction of autoantibody production is limited in nonautoimmune mice

Many individuals develop a single or a few brief episodes of autoimmunity from which they recover. Mechanisms that quell pathologic autoimmunity following such a breakdown of self-tolerance are not clearly understood. In this study, we show that in nonautoimmune mice, dsDNA-specific autoreactive B cells exist but remain inactive. This state of inactivation in dsDNA-specific B cells could be disrupted by autoreactive Th cells; in this case T cells that react with peptides from the V(H) region of anti-DNA Abs (hereafter called anti-V(H) T cells). Immunization with anti-DNA mAb, its gamma-chain or peptides derived from its V(H) region induced anti-V(H) Th cells, IgG anti-dsDNA Ab, and proteinuria. The breakdown of B cell tolerance in nonautoimmune mice, however, was short-lived: anti-DNA Ab and nephritis subsided despite subsequent immunizations. The recovery from autoimmunity temporally correlated with the appearance of T cells that inhibited anti-DNA Ab production. Such inhibitory T cells secreted TGFbeta; the inhibition of anti-DNA Ab production by these cells was partly abolished by anti-TGFbeta Ab. Even without immunization, nonautoimmune mice possess T cells that can inhibit autoantibody production. Thus, inhibitory T cells in nonautoimmune mice may normally inhibit T-dependent activation of autoreactive B cells and/or reverse such activation following stimulation by Th cells. The induction of such inhibitory T cells may play a role in protecting nonautoimmune mice from developing chronic autoimmunity.

The mechanism by which a peptide based on complementarity-determining region-1 of a pathogenic anti-DNA auto-Ab ameliorates experimental systemic lupus erythematosus

A peptide based on complementarity-determining region (CDR)-1 of a monoclonal murine anti-DNA Ab that bears the common idiotype, 16/6Id, was synthesized and characterized. The peptide, designated pCDR1, was found to be an immunodominant T-cell epitope in BALB/c mice. The CDR1-based peptide was shown to be capable of inhibiting the in vivo priming of BALB/c mice immunized with the peptide or with the whole anti-DNA 16/6Id(+) mAbs of either mouse or human origin. We show here that administration of pCDR1 (weekly, i.v., 100 microgram/mouse) in aqueous solution for 5 weeks starting at the time of disease induction with the human 16/6Id prevented the development of clinical manifestations of experimental systemic lupus erythematosus (SLE). Further, 10 weekly injections of pCDR1 to BALB/c mice with an established experimental SLE down-regulated clinical manifestations of SLE (e.g., anti-DNA auto-Abs, leukopenia, proteinuria, immune complex deposits in the kidneys) in the treated mice. Prevention of SLE induction was shown to be associated mainly with a decrease in the levels of IL-2, INFgamma, and the proinflammatory cytokine TNFalpha. On the other hand, the secretion of the immunosuppressive cytokine TGFbeta was elevated. Amelioration of the clinical manifestations of an already established experimental SLE correlated with a dramatic decrease in TNFalpha secretion, elevated levels of TGFbeta, and immunomodulation of the Th1 and Th2 type cytokines to levels close to those observed in healthy mice.

Progression from acute to chronic disease in a murine parent-into-F1 model of graft-versus-host disease

The parent-into-immunocompetent-F(1) model of graft-vs-host disease (GVHD) induces immune dysregulation, resulting in acute or chronic GVHD. The disease outcome is thought to be determined by the number of parental anti-F(1) CTL precursor cells present in the inoculum. Injection of C57BL/6 (B6) splenocytes into (B6 x DBA/2)F(1) (B6D2F(1)) mice (acute model) leads to extensive parental cell engraftment and early death, whereas injection of DBA/2 cells (chronic model) results in little parental cell engraftment and a lupus-like disease. This study demonstrated that injection of BALB/c splenocytes into (BALB/c x B6)F(1) (CB6F(1)) mice resulted in little engraftment of parental lymphocytes and the development of lupus as expected. Injection of B6 splenocytes into CB6F(1) initiated an initial burst of parental cell engraftment similar to that of B6 into B6D2F(1). However, the acute disease resolved, and the CB6F(1) mice went on to develop chronic GVHD with detectable Abs to ssDNA, dsDNA, and extractable nuclear Ags. Limiting dilution CTL assays determined that B6 splenocytes have CTL precursor frequencies of 1/1000 against both CB6F(1) and B6D2F(1), whereas DBA/2 and BALB/c splenocytes have a CTL precursor frequency of 1/20,000 for their respective F(1)s. The Th cell precursor frequency for B6 anti-DBA/2 was 3-fold higher than that for B6 anti-BALB/c determined by limiting dilution proliferation assays. These results indicate the importance of adequate allospecific helper as well as effector T cells for the induction and maintenance of acute GVHD in this model, and presents an unexpected model in which initial acute GVHD is replaced by the chronic form of disease.

A peptide based on the sequence of the CDR3 of a murine anti-DNA mAb is a better modulator of experimental SLE than its single amino acid-substituted analogs

A peptide based on the complementarity determining region (CDR) 3 of a pathogenic anti-DNA 16/6 Id(+) monoclonal antibody was previously shown to be a dominant T-cell epitope in experimental SLE, and to be capable of inhibiting SLE-associated proliferative responses. Single amino acid-substituted analogs of pCDR3 were designed and analyzed for their ability to stimulate or inhibit the proliferation of a pCDR3-specific T-cell line. Alterations in positions 9 and 10 neutralized the proliferative potential of pCDR3, whereas alterations in positions 6-8 and 11-15 retained the proliferative potential of the peptides. Similar to pCDR3, its analogs Ala11 and Nle13 inhibited efficiently the in vivo priming of lymph node cells either to pCDR3 or to the human monoclonal anti-DNA 16/6 Id(+) antibody. Substituting both positions 11 (Tyr --> Ala) and 13 (Met --> Nle) reduced this inhibitory capacity compared to the single substituted analogs. Also, truncation of pCDR3 at the C- and/or N-terminus obliterated the inhibitory activities of the peptide. Analogs Ala11 and Nle13 immunomodulated serological and clinical smanifestations of experimental SLE. Nevertheless, the original pCDR3 was a more efficient modulator of the disease.