Updates on Clinical Trials in Systemic Lupus Erythematosus.

PURPOSE OF REVIEW: Because of the complexity of systemic lupus erythematosus (SLE), different approaches are undertaken while investigating potential therapeutic compounds to treat the disease. The purpose of this review is to summarize the results from recent clinical trials, which investigated different compounds for treating SLE. RECENT FINDINGS: Targeting B cells and type I interferons constitutes the major focus in recent clinical trials. The potential for therapeutic effects of small molecule inhibition such as JAK, Tyk, and Btk is now being investigated for treating SLE. The immunoregulation of T cell activation in SLE is studied using low-dose IL-2 and CD40 ligand inhibition. There are clinical trials that study bispecific antibodies, with binding specificities for 2 different target molecules related to T- and B-cell activation or to different aspects of B cell activation. An approach of combination treatment is also being studied. Clinical trials are underway and new treatment compounds for SLE are being anticipated.

Indoleamine-2,3-dioxygenase in murine and human systemic lupus erythematosus: Down-regulation by the tolerogeneic peptide hCDR1.

וֹndoleamine-2,3-dioxygenase (IDO) plays a role in immune regulation. Increased IDO activity was reported in systemic lupus erythematosus (SLE). We investigated the effects of the tolerogenic peptide hCDR1, shown to ameliorate lupus manifestations, on IDO gene expression. mRNA was prepared from splenocytes of hCDR1- treated SLE-afflicted (NZBxNZW)F1 mice, from blood samples of lupus patients, collected before and after their in vivo treatment with hCDR1 and from peripheral blood mononuclear cells (PBMC) of patients incubated with hCDR1. IDO gene expression was determined by real-time RT-PCR. hCDR1 significantly down-regulated IDO expression in SLE-affected mice and in lupus patients (treated in vivo and in vitro). No effects were observed in healthy donors or following treatment with a control peptide. Diminished IDO gene expression was associated with hCDR1 beneficial effects. Our results suggest that the hCDR1-induced FOXP3 expressing regulatory T cells in lupus are not driven by IDO but rather by other hCDR1 regulated pathways.

The serine/threonine protein phosphatase 2A controls autoimmunity.

Protein phosphatase 2A (PP2A) is the first serine/threonine phosphatase recognized to contribute to human and murine lupus immunopathology. PP2A expression in SLE is controlled both epigenetically and genetically, and it is increased in patients with SLE, which contributes to decreased IL-2 production, decreased CD3ζ and increased FcRγ expression on the surface of T cells, increased CREMα expression, hypomethylation of genes associated with SLE pathogenesis, and increased IL-17 production. ß regulatory subunit of PP2A regulates IL-2 deprivation-induced T cell death and is decreased in SLE patients. A mouse overexpressing PP2Ac in T cells displays peripheral granulocytosis, elevated IL-17 production, and develops glomerulonephritis when challenged. A mouse which lacks PP2Ac only in regulatory T cells develops severe autoimmunity and multiorgan inflammation because of loss of restraint on mTORC1 and inability of Foxp3+ cells to regulate conventional T cells. Targeting PP2A in T cell subsets may be therapeutic for SLE and other autoimmune diseases.

The tolerogenic peptide hCDR1 immunomodulates cytokine and regulatory molecule gene expression in blood mononuclear cells of primary Sjogren's syndrome patients.

Primary Sjogren's syndrome (pSS) is an autoimmune disease characterized by lymphocytic infiltration of exocrine glands. We investigated whether the tolerogenic peptide, hCDR1, that ameliorates lupus manifestations would have beneficial effects on pSS as well. The in vitro effects of hCDR1 on gene expression of pro-inflammatory cytokines and regulatory molecules were tested in peripheral blood mononuclear cells (PBMC) of 16 pSS patients. hCDR1, but not a control peptide, significantly reduced gene expression of IL-1ß, TNF-α, MX-1 and BlyS and up-regulated immunosuppressive (TGF-ß, FOXP3) molecules in PBMC of pSS patients. hCDR1 did not affect gene expression in patients with rheumatoid arthritis and anti-phospholipid syndrome. Further, hCDR1 up-regulated the expression of Indoleamine 2,3-dioxygenase (IDO) via elevation of TGF-ß. IDO inhibition led to a significant decrease in the expression of FOXP3 which is crucial for the induction of T regulatory cells. Thus, hCDR1 is potential candidate for the specific treatment of pSS patients.

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.

A role for the B-cell CD74/macrophage migration inhibitory factor pathway in the immunomodulation of systemic lupus erythematosus by a therapeutic tolerogenic peptide.

Systemic lupus erythematosus (SLE) is an autoimmune disease that involves dysregulation of B and T cells. A tolerogenic peptide, designated hCDR1, ameliorates disease manifestations in SLE-afflicted mice. In the present study, the effect of treatment with hCDR1 on the CD74/macrophage migration inhibitory factor (MIF) pathway was studied. We report here that B lymphocytes from SLE-afflicted mice express relatively elevated levels of CD74, compared with B cells from healthy mice. CD74 is a receptor found in complex with CD44, and it binds the pro-inflammatory cytokine MIF. The latter components were also up-regulated in B cells from the diseased mice, and treatment with hCDR1 resulted in their down-regulation and in reduced B-cell survival. Furthermore, up-regulation of CD74 and CD44 expression was detected in brain hippocampi and kidneys, two target organs in SLE. Treatment with hCDR1 diminished the expression of those molecules to the levels determined for young healthy mice. These results suggest that the CD74/MIF pathway plays an important role in lupus pathology.

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.

Bcl-xL is required for the development of functional regulatory CD4 cells in lupus-afflicted mice following treatment with a tolerogenic peptide.

Dysregulated expression of Bcl-xL and Bcl-2 may initiate the development of autoimmune diseases including systemic lupus erythematosus (SLE). A tolerogenic peptide designated hCDR1 was shown to ameliorate manifestations of spontaneous and induced murine SLE. Recently, we demonstrated that Bcl-xL plays a critical role in the modulating effects of hCDR1, as manifested by reducing the state of activation of lymphocytes and by down-regulating the secretion of the pathogenic cytokines, IFN-gamma and IL-10. Here we studied the role of Bcl-xL in the development and function of CD4 regulatory T-cells (Treg) from hCDR1-treated, SLE-afflicted (New-Zealand-Black x New-Zealand-White) F1 mice. We report that Bcl-xL was up-regulated in CD4 Treg of tolerized mice, where it played a role in inducing the regulatory/inhibitory molecules Foxp3, CTLA-4, and TGF-beta and in repressing PD-1. Further, Bcl-xL mediated the induction of CTLA-4 and TGF-beta in effector T cells (Teff) by CD4 Treg of the tolerized mice. The induction of Bcl-xL in Teff by Treg was TGF-beta dependent and CTLA-4 independent, leading to inhibition of proliferation and to a decrease in activated Teff. We conclude that Bcl-xL is required for the development and function of CD4 Treg, which ameliorate lupus following treatment with a tolerogenic peptide.

The suppression of murine lupus by a tolerogenic peptide involves foxp3-expressing CD8 cells that are required for the optimal induction and function of foxp3-expressing CD4 cells.

A peptide, designated human CDR1 (hCDR1), that is based on the CDR1 of an anti-DNA Ab ameliorates systemic lupus erythematosus (SLE) in murine models via the induction of CD4(+)CD25(+) regulatory T cells (Tregs). In the present study, the involvement of CD8 Tregs in the mode of action of hCDR1 was investigated in SLE-afflicted (NZB x NZW)F1 mice and in SJL mice following immunization with the lupus-inducing anti-DNA mAb that bears a common Id, 16/6Id. Treatment with hCDR1 up-regulated Foxp3-expressing CD8(+)CD28(-) Tregs in association with clinical amelioration of lupus manifestations. Furthermore, the in vivo depletion of the latter cells diminished the clinical improvement and the inhibitory effects of hCDR1 on the secretion of IFN-gamma and resulted in the up-regulation of IL-10. However, the stimulatory effect of hCDR1 on the secretion of TGF-beta was not affected by the CD8 Tregs. In the absence of CD8 Tregs, CD4(+)CD25(+) Tregs were unable to expand in the hCDR1-treated mice, and the expression of Foxp3 was reduced, thereby interfering further with the suppressive function of CD4(+)CD25(+) Tregs as determined in the in vitro assays. However, CD8 cells from hCDR1-treated mice that were adoptively transferred into SLE-afflicted mice led to up-regulation of CD4(+)CD25(+) cells with intensified Foxp3 expression in the recipient mice. Thus, a functional link between two subsets of Tregs is demonstrated in which CD8(+)CD28(-) Tregs are required for both the optimal expansion and function of lupus ameliorating hCDR1-induced CD4(+)CD25(+) Tregs.

T cell metabolism: new insights in systemic lupus erythematosus pathogenesis and therapy.

T cell subsets are critically involved in the development of systemic autoimmunity and organ inflammation in systemic lupus erythematosus (SLE). Each T cell subset function (such as effector, helper, memory or regulatory function) is dictated by distinct metabolic pathways requiring the availability of specific nutrients and intracellular enzymes. The activity of these enzymes or nutrient transporters influences the differentiation and function of T cells in autoimmune responses. Data are increasingly emerging on how metabolic processes control the function of various T cell subsets and how these metabolic processes are altered in SLE. Specifically, aberrant glycolysis, glutaminolysis, fatty acid and glycosphingolipid metabolism, mitochondrial hyperpolarization, oxidative stress and mTOR signalling underwrite the known function of T cell subsets in patients with SLE. A number of medications that are used in the care of patients with SLE affect cell metabolism, and the development of novel therapeutic approaches to control the activity of metabolic enzymes in T cell subsets represents a promising endeavour in the search for effective treatment of systemic autoimmune diseases.

PPP2R2D suppresses IL-2 production and Treg function.

Protein phosphatase 2A is a ubiquitously expressed serine/threonine phosphatase that comprises a scaffold, a catalytic, and multiple regulatory subunits and has been shown to be important in the expression of autoimmunity. We considered that a distinct subunit may account for the decreased production of IL-2 in people and mice with systemic autoimmunity. We show that the regulatory subunit PPP2R2D is increased in T cells from people with systemic lupus erythematosus and regulates IL-2 production. Mice lacking PPP2R2D only in T cells produce more IL-2 because the IL-2 gene and genes coding for IL-2-enhancing transcription factors remain open, while the levels of the enhancer phosphorylated CREB are high. Mice with T cell-specific PPP2R2D deficiency display less systemic autoimmunity when exposed to a TLR7 stimulator. While genes related to Treg function do not change in the absence of PPP2R2D, Tregs exhibit high suppressive function in vitro and in vivo. Because the ubiquitous expression of protein phosphatase 2A cannot permit systemic therapeutic manipulation, the identification of regulatory subunits able to control specific T cell functions opens the way for the development of novel, function-specific drugs.

Systemic lupus erythematosus favors the generation of IL-17 producing double negative T cells.

Mature double negative (DN) T cells are a population of αß T cells that lack CD4 and CD8 coreceptors and contribute to systemic lupus erythematosus (SLE). The splenic marginal zone macrophages (MZMs) are important for establishing immune tolerance, and loss of their number or function contributes to the progression of SLE. Here we show that loss of MZMs impairs the tolerogenic clearance of apoptotic cells and alters the serum cytokine profile, which in turn provokes the generation of DN T cells from self-reactive CD8+ T cells. Increased Ki67 expression, narrowed TCR V-beta repertoire usage and diluted T-cell receptor excision circles confirm that DN T cells from lupus-prone mice and patients with SLE undergo clonal proliferation and expansion in a self-antigen dependent manner, which supports the shared mechanisms for their generation. Collectively, our results provide a link between the loss of MZMs and the expansion of DN T cells, and indicate possible strategies to prevent the development of SLE.

Serine/threonine phosphatase PP2A is essential for optimal B cell function.

Protein phosphatase 2A (PP2A), a serine/threonine phosphatase, has been shown to control T cell function. We found that in vitro-activated B cells and B cells from various lupus-prone mice and patients with systemic lupus erythematosus display increased PP2A activity. To understand the contribution of PP2A to B cell function, we generated a Cd19CrePpp2r1afl/fl (flox/flox) mouse which lacks functional PP2A only in B cells. Flox/flox mice displayed reduced spontaneous germinal center formation and decreased responses to T cell-dependent and T-independent antigens, while their B cells responded poorly in vitro to stimulation with an anti-CD40 antibody or CpG in the presence of IL-4. Transcriptome and metabolome studies revealed altered nicotinamide adenine dinucleotide (NAD) and purine/pyrimidine metabolism and increased expression of purine nucleoside phosphorylase in PP2A-deficient B cells. Our results demonstrate that PP2A is required for optimal B cell function and may contribute to increased B cell activity in systemic autoimmunity.

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.

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 tolerogenic peptide that induces suppressor of cytokine signaling (SOCS)-1 restores the aberrant control of IFN-gamma signaling in lupus-affected (NZB x NZW)F1 mice.

Interferon-gamma (IFN-gamma) plays a pathogenic role in systemic lupus erythematosus (SLE). Uncontrolled IFN-gamma signaling may result from a deficiency in the negative regulator, namely, suppressor of cytokine signaling-1 (SOCS-1). We investigated the activation status of IFN-gamma signaling pathway in SLE-afflicted (New-Zealand-BlackxNew-Zealand-White)F1 mice and determined its responsiveness when treating with a tolerogenic peptide, hCDR1, which ameliorates SLE. SOCS-1 was suppressed and pSTAT1 was enhanced in spleen-derived cells from SLE-affected mice as compared with healthy controls. Treatment with hCDR1 reversed the expression of these two molecules in association with clinical amelioration. In vitro stimulation with IFN-gamma resulted in elevated levels of SOCS-1 in cells from both vehicle and hCDR1-treated mice but this effect reached significance only in cells of the latter group, which also exhibited reduced levels of pSTAT1. Thus, SOCS-1 is diminished in SLE-affected mice, and treatment with hCDR1 results in its up-regulation thereby restoring control of IFN-gamma signaling pathway.

B-cell activating factor (BAFF) plays a role in the mechanism of action of a tolerogenic peptide that ameliorates lupus.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by dysregulated immune responses mediated by T and B cells. A tolerogenic peptide, designated hCDR1, ameliorated the serological and clinical manifestations of SLE in mouse models of lupus. We investigated the role of B-cell activating factor (BAFF) in the beneficial effects of hCDR1. BAFF production was reduced in hCDR1-treated mice in association with diminished production of dsDNA-specific autoantibodies and proteinuria levels. In addition, IFN-gamma and IL-10, which induce BAFF secretion, were down-regulated in hCDR1-treated mice. The reduced levels of BAFF correlated with a lower rate of maturation and differentiation of B cells, and with a decrease in integrin expression and anti-apoptotic gene expression by B cells. Moreover, BAFF signaling through the NF-kB pathways was inhibited in hCDR1-treated mice. Thus, down-regulation of BAFF plays a role in the mechanism of action by which hCDR1 ameliorates lupus manifestations.

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.