Amir Sharabi

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 × 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-γ and resulted in the up-regulation of IL-10. However, the stimulatory effect of hCDR1 on the secretion of TGF-β 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.

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.

The role of CD8+CD28− regulatory cells in suppressing myasthenia gravis-associated responses by a dual altered peptide ligand

Myasthenia gravis (MG) and experimental autoimmune MG are T cell-dependent antibody-mediated autoimmune diseases. A dual altered peptide ligand (APL), composed of the tandemly arranged two single amino acid analogs of two myasthenogenic peptides, p195-212 and p259-271, down-regulated in vitro and in vivo MG-associated T cell responses. In the present study, we investigated the role of CD8+CD28− regulatory cells in the mechanism of action of the dual APL. We demonstrated that treatment of mice with the dual APL concomitant with immunization with a myasthenogenic peptide resulted in an increased population of CD8+CD28− cells that express forkhead box P3 (Foxp3). The dual APL inhibited the proliferation of lymph node (LN) cells of the Torpedo acetylcholine receptor-immunized WT C57BL/6 mice, whereas the inhibition was abrogated in CD8−/− knockout mice. Moreover, the dual APL did not inhibit the secretion of IFN-γ by LN cells from CD8−/− mice immunized with Torpedo acetylcholine receptor. However, the mRNA expression of IL-10 and TGF-β by LN cells from CD8−/− mice was up-regulated similarly to that of the WT mice. Furthermore, the dual APL elevated the proapoptotic markers caspases 3 and caspase 8, whereas it down-regulated the antiapoptotic marker Bcl-xL in both CD8−/− and WT mice. Finally, the dual APL-induced CD4+CD25+Foxp3+ cells were up-regulated in CD8−/− mice to a similar extent to that observed in the WT mice. Thus, we suggest that CD8+CD28− regulatory cells play a partial role in the mechanism of action by which the dual APL suppresses experimental autoimmune MG-associated T cell responses.

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 × NZW) F1 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‐γ and interleukin‐10, and up‐regulated transforming growth factor‐β. 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+ CD45RBlow 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 Role of Apoptosis in the Ameliorating Effects of a CDR1-Based Peptide on Lupus Manifestations in a Mouse Model

Experimental systemic lupus erythematosus (SLE) can be induced in mice following immunization with an anti-DNA mAb expressing a major Id, 16/6Id. Treatment with a peptide, designated human CDR1 (hCDR1; Edratide), that is based on the sequence of CDR1 of the 16/6Id ameliorated disease manifestations. In the present study, we investigated the roles of apoptosis and related molecules in BALB/c mice with induced experimental SLE following treatment with hCDR1. A higher state of activation and increased rate of apoptosis were found in lymphocytes of SLE-afflicted mice as compared with healthy controls. The latter effects were associated with up-regulated caspase-8 and caspase-3, and down-regulated Bcl-xL. The ameliorative effects of hCDR1 were associated with down-regulation of caspase-8 and caspase-3, up-regulation of Bcl-xL, and a reduced rate of apoptosis. Treatment of diseased mice with an apoptosis-reducing compound that inhibited caspases down-regulated the secretion of the pathogenic cytokine IFN-γ and lowered the intensity of glomerular immune complex deposits and the levels of proteinuria. Furthermore, coincubation of Bcl-xL inhibitors with hCDR1-treated cells abrogated the ability of hCDR1 to reduce the activation state of lymphocytes and to down-regulate the secretion of IL-10 and IFN-γ. Moreover, the Bcl-xL-expressing CD4+CD25+ cells from hCDR1-treated mice induced the expression of Bcl-xL in CFSE-labeled CD4+CD25− cells of the SLE-afflicted mice. Thus, the reduction of apoptosis and the up-regulation of Bcl-xL, which plays an apparent role in tolerance induction, contribute to at least part of the beneficial effects of hCDR1 on lupus manifestations.

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 novel tolerogenic peptide, hCDR1, for the specific treatment of systemic lupus erythematosus.

Treatment with a tolerogenic peptide, hCDR1, designed for the specific treatment of systemic lupus erythematosus (SLE) ameliorated the serological and kidney-related clinical manifestations in murine models of induced and spontaneous lupus. Furthermore, hCDR1 reduced brain pathology and improved behavior parameters in mice with central nervous system manifestations. The beneficial effects were associated with a diminished production of pathogenic cytokines (e.g. IFN-γ, IL-10, and IL-1β) and with increased production of the immunosuppressive cytokine, TGF-β. Treatment with hCDR1 up-regulated CD4 and CD8 regulatory T cells (Tregs) that played a key role in the ameliorating effects of hCDR1. Reduction of T cell apoptosis by hCDR1 contributed to the beneficial effects of hCDR. Moreover, treatment with hCDR1 down-regulated B cell maturation and autoreactive B cell survival by diminishing the B cell activating factor (BAFF/BLyS). Finally, hCDR1 suppressed in vivo gene expression of pathogenic cytokines, apoptosis and BLyS and up-regulated immunosuppressive molecules in peripheral blood lymphocytes of SLE patients. The latter was associated with clinical amelioration. Thus, treatment with hCDR1 leads to a cascade of events that culminate in the down-regulation of SLE-associated autoreactive T and B cells and in the clinical amelioration of lupus. hCDR1 is therefore a candidate for the specific treatment of SLE patients.

Chemoimmunotherapy Reduces the Progression of Multiple Myeloma in a Mouse Model

Multiple myeloma (MM) is a B-cell malignancy characterized by clonal proliferation of malignant plasma cells in the bone marrow. Recently, we showed a correlation between increased ratios of functional regulatory T cells (Treg) and disease progression in a unique mouse model that mimics the human disease. Cyclophosphamide (CYC) is a cytotoxic alkylating agent widely used in chemotherapeutic regimens. Low-dose CYC was previously reported to selectively reduce Treg levels and to contribute to immunostimulation. Our objectives were (a) to determine whether treatment using a low-dose CYC could reduce MM progression and (b) to further characterize the modes of action underlying these effects. We found that both low- and high-dose CYC given to sick mice with hind limb paralysis resulted in the disappearance of the paralysis, the replacement of plasma tumor cells in the bone marrow by normal cell populations, and a significant prolongation of survival. However, only low-dose CYC treatment decreased the incidence of MM. Low-dose CYC rendered Tregs susceptible to apoptosis because of the downregulation of Bcl-xL and CTLA-4 in these cells, and a decreased production of interleukin 2 by effector CD4 cells. Moreover, using this treatment, we noted the recovery of IFN-γ–producing natural killer T cells and maturation of dendritic cells. Treatment of tumor-bearing mice with repeated administrations of low-dose CYC at longer time intervals (coinciding with the blocked renewal of Tregs) resulted in reduced tumor load, and the prevention or delay of disease recurrence, thereby breaking immune tolerance against MM tumor cells. Cancer Prev Res; 3(10); 1265–76. ©2010 AACR.

Amelioration of brain pathology and behavioral dysfunction in mice with lupus following treatment with a tolerogenic peptide

OBJECTIVE Central nervous system (CNS) involvement in systemic lupus erythematosus (SLE) is manifested by neurologic deficits and psychiatric disorders. The aim of this study was to examine SLE-associated CNS pathology in lupus-prone (NZBxNZW)F1 (NZB/NZW) mice, and to evaluate the ameliorating effects of treatment with a tolerogenic peptide, hCDR1 (human first complementarity-determining region), on these manifestations. METHODS Histopathologic analyses of brains from lupus-prone NZB/NZW mice treated with vehicle, hCDR1, or a control scrambled peptide were performed. The messenger RNA expression of SLE-associated cytokines and apoptosis-related molecules from the hippocampi was determined. Anxiety-like behavior was assessed by open-field tests and dark/light transfer tests, and memory deficit was assessed using a novel object recognition test. RESULTS Infiltration was evident in the hippocampi of the lupus-afflicted mice, and the presence of CD3+ T cells as well as IgG and complement C3 complex deposition was observed. Furthermore, elevated levels of gliosis and loss of neuronal nuclei immunoreactivity were also observed in the hippocampi of the mice with lupus. Treatment with hCDR1 ameliorated the histopathologic changes. Treatment with hCDR1 down-regulated the high expression of interleukin-1beta (IL-1beta), IL-6, IL-10, interferon-gamma, transforming growth factor beta, and the proapoptotic molecule caspase 8 in the hippocampi of the mice with lupus, and up-regulated expression of the antiapoptotic bcl-xL gene. Diseased mice exhibited increased anxiety-like behavior and memory deficit. Treatment with hCDR1 improved these parameters, as assessed by behavior tests. CONCLUSION Treatment with hCDR1 ameliorated CNS pathology and improved the tested cognitive and mood-related behavior of the mice with lupus. Thus, hCDR1 is a novel candidate for the treatment of CNS lupus.

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‐γ (IFN‐γ) secretion. Moreover, DCs derived from hCDR1‐treated mice downregulated proliferation and IFN‐γ secretion by T cells from untreated mice. Upregulation of transforming growth factor‐β (TGF‐β) secretion by T cells, following treatment with hCDR1, resulted in downregulation of IFN‐γ 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‐β 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.