The cytokine network in the pathogenesis of systemic lupus erythematosus and possible therapeutic implications

Urinary biomarkers in lupus nephritis

Systemic lupus erythematosus (SLE) is the prototypical autoimmune disease that can affect any organ of the body. Multiple mechanisms may contribute to the pathophysiology of systemic lupus, including failure to remove apoptotic bodies, hyperactivity of self-reactive B and T lymphocytes, abnormal exposure to autoantigens, and increased levels of B-cell stimulatory cytokines. The involvement of the kidney, called lupus nephritis (LN), during the course of the disease affects between 30% and 60% of adult SLE patients, and up to 70% of children. LN is an immune-mediated glomerulonephritis that is a common and serious finding in patients with SLE. Nowadays, renal biopsy is considered the gold standard for classifying LN, besides its degree of activity or chronicity. Nevertheless, renal biopsy lacks the ability to predict which patients will respond to immunosuppressive therapy and is a costly and risky procedure that is not practical in the monitoring of LN because serial repetitions would be necessary. Consequently, many serum and urinary biomarkers have been studied in SLE patients for the complementary study of LN, existing conventional biomarkers like proteinuria, protein/creatinine ratio in spot urine, 24 ​h urine proteinuria, creatinine clearance, among others and non-conventional biomarkers, like Monocyte chemoattractant protein-1 (MCP-1), have been correlated with the histological findings of the different types of LN. In this article, we review the advances in lupus nephritis urinary biomarkers. Such markers ideally should be capable of predicting early sub-clinical flares and could be used to follow response to therapy. In addition, some of these markers have been found to be involved in the pathogenesis of lupus nephritis.

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.

Safety and efficacy of hCDR1 (Edratide) in patients with active systemic lupus erythematosus: results of phase II study

Objective

To evaluate the safety and efficacy of hCDR1 (Edratide) in patients with systemic lupus erythematosus (SLE).

Methods

Patients (n=340) with SLE ≥4 ACR criteria (4–11, mean 7) with active disease (SLEDAI-2K of 6–12). Patients were on average 7.1 years post-diagnosis and their organ involvement was mainly musculoskeletal, mucocutaneous and haematologic. Placebo or Edratide was administered subcutaneously weekly at doses of 0.5, 1.0 or 2.5 mg. The co-primary endpoints were SLEDAI-2K SLE Disease Activity and Adjusted Mean SLEDAI (AMS) reduction in patients compared with controls using a landmark analysis. Secondary outcomes were improvement in British Isles Lupus Assessment Group (BILAG) Responder Index and medicinal flare analysis.

Results

Edratide was safe and well tolerated. The primary endpoints based solely on SLEDAI-2K and AMS were not met. The secondary predefined endpoint, BILAG, was met for the 0.5 mg Edratide arm in the intention to treat (ITT) cohort (N=316) (OR=2.09, p=0.03) with trends in the 1.0 and 2.5 mg doses. There was also a positive trend in the Composite SLE Responder Index of the ITT cohort. Post hoc analysis showed that the BILAG secondary endpoint was also met for the 0.5 mg Edratide for a number of subgroup dose levels, including low or no steroids, seropositivity and patients with 2 grade BILAG improvement.

Conclusions

The favourable safety profile and encouraging clinically significant effects noted in some of the endpoints support the need for additional longer term Edratide studies that incorporate recent advances in the understanding and treatment of SLE, including steroid treatment algorithms, and using a composite primary endpoint which is likely to include BILAG.

Trial registration number

NCT00203151.

The tolerogenic peptide, hCDR1, down-regulates the expression of interferon-α in murine and human systemic lupus erythematosus

BACKGROUND

The tolerogenic peptide, hCDR1, ameliorated manifestations of systemic lupus erythematosus (SLE) via the immunomodulation of pro-inflammatory and immunosuppressive cytokines and the induction of regulatory T cells. Because type I interferon (IFN-α) has been implicated to play a role in SLE pathogenesis, we investigated the effects of hCDR1 on IFN-α in a murine model of SLE and in human lupus.

METHODOLOGY PRINCIPAL FINDINGS

(NZBxNZW)F1 mice with established SLE were treated with hCDR1 (10 weekly injections). Splenocytes were obtained for gene expression studies by real-time RT-PCR. hCDR1 down-regulated significantly IFN-α gene expression (73% inhibition compared to vehicle treated mice, p = 0.002) in association with diminished clinical manifestations. Further, hCDR1 reduced, in vitro, IFN-α gene expression in peripheral blood mononuclear cells (PBMC) of 10 lupus patients (74% inhibition compared to medium, p = 0.002) but had no significant effects on the expression levels of IFN-α in PBMC of primary anti-phospholipid syndrome patients or of healthy controls. Lupus patients were treated for 24 weeks with hCDR1 (5) or placebo (4) by weekly subcutaneous injections. Blood samples collected, before and after treatment, were frozen until mRNA isolation. A significant reduction in IFN-α was determined in hCDR1 treated patients (64.4% inhibition compared to pretreatment expression levels, p = 0.015). No inhibition was observed in the placebo treated patients. In agreement, treatment with hCDR1 resulted in a significant decrease of disease activity. IFN-α appears to play a role in the mechanism of action of hCDR1 since recombinant IFN-α diminished the immunomodulating effects of hCDR1 on IL-1β, TGFβ and FoxP3 gene expression.

CONCLUSIONS SIGNIFICANCE

We reported previously that hCDR1 affected various cell types and immune pathways in correlation to disease amelioration. The present studies demonstrate that hCDR1 is also capable of down-regulating significantly (and specifically to lupus) IFN-α gene expression. Thus, hCDR1 has a potential role as a novel, disease specific treatment for lupus.

Tumour necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6) and their soluble receptors (sTNF-alpha-Rp55 and slL-6R) serum levels in systemic lupus erythematodes

We investigated a possible association between serum concentrations of tumour necrosis factor α (TNF-α), interleukin-6 (IL-6) and their soluble receptors (sTNF-α-Rp55 and sIL-6R) using an enzyme-linked immunosorbent assay (ELISA) in 55 patients with systemic lupus erythematodes (SLE) and 16 healthy controls. We also examined a possible association between the serum levels of these peptides and SLE activity, as well as TNF-α and IL-6 concentrations and the levels of their soluble receptors. The median concentrations of TNF-α, sTNF-α-Rp55 and IL-6 were significantly higher in SLE patients than in normal individuals. In contrast, there was no difference between the serum level of sIL-6R in both groups. We found positive correlations between the serum concentrations of TNF-α and IL-6 as well as their soluble receptors and disease activity. There were also correlations between TNF-α and sTNF-α-Rp55 as well as IL-6 and sIL-6R serum levels in SLE patients but there were no such correlations in the normal control group. In conclusion, an increase in the serum levels of TNF-α, sTNF-α-Rp55 and IL-6 may become useful markers for SLE activity. Patients with SLE have sIL-6R serum concentration similar to that as in normal individuals. However, it correlates with disease activity and the level of IL-6.

High circulating levels of interleukin-18 binding protein indicate the severity of glomerular involvement in systemic lupus erythematosus

In systemic lupus erythematosus (SLE), glomerular involvement often progresses with the activity of the disease. Immune complexes and abnormal secretion of cytokines are thought to be involved in the central mechanism of the development of lupus nephritis. We investigated serum levels of interleukin 18 (IL-18), a proinflammatory cytokine, and its natural antagonist IL-18 binding protein (IL-18 BP) in 45 patients with lupus nephritis. IL-18 levels were significantly increased in patients with Class II, Class III, and Class IV lupus nephritis compared with the level in a healthy control group. However, the levels stayed within the non-significant range in Class V. IL-18 BP levels were significantly increased in patients with Class III and Class IV lupus nephritis, in which histological activity and chronicity are severe. However, IL-18 BP levels stayed within the non-significant range in Class II and Class V, in which histological markers are mild. We also compared the levels of IL-18 and IL-18 BP in patients with and without glomerular infiltration of inflammatory cells. IL-18 was increased regardless of glomerular infiltration. However, IL-18 BP was increased only in patients with glomerular infiltration. These data suggest that IL-18 levels indicate the extent of the offending inflammatory response not only in the bloodstream but also in renal tissue, and that high IL-18 BP levels indicate the severity of existing glomerular injury.

Accelerated atherosclerosis in systemic lupus erythematosus: role of proinflammatory cytokines and therapeutic approaches

Systemic lupus erythematosus (SLE), a chronic multisystem autoimmune disease with a broad range of clinical manifestations, is associated with accelerated atherosclerosis (AT) and increased risk of cardiovascular complications. Relevant factors directly influencing the development of AT comprise immune complex generation, complement activation, and changes in the production and activity of a complex network of cytokines, including type I and II interferons, B lymphocyte stimulator (BLyS), TNFα, IL-6, IL-17 and migration macrophage inhibitor (MIF). Autoantibodies, also responsible for cytokine expression and activation, play a supplementary key role in the development of AT. Genomic and proteomic studies have contributed to the discovery of genes and proteins involved in AT, including some that may be suitable to be used as biomarkers. All that data has allowed the development of new drugs, most of them evaluated in clinical trials: inhibitors of IFN and TNFα, B cell directed therapies, synthetic oligodeoxynucleotides, intravenous immunoglobulin, or statins. The focus of the present paper is to summarize recent evidence showing the role of cytokines in the development of AT in SLE and the rationale, and safety concerns, in the use of combined therapy to prevent AT and cardiovascular disease.

Transgenic overexpression of anti-double-stranded DNA autoantibody and activation of Toll-like receptor 4 in mice induce severe systemic lupus erythematosus syndromes

Systemic lupus erythematosus (SLE) is a multi-organ autoimmune disease characteristized by the presence of autoantibodies against double-stranded DNA (anti-dsDNA) in sera at high levels. Bacterial infections in SLE are associated with higher morbidity and mortality. Our goal was to observe the interaction between these 2 factors in the pathogenesis of lupus. We generated transgenic mice with monoclonal anti-dsDNA to investigate the development of lupus. By challenging the mice in vitro and in vivo with Toll-like receptor 4 (TLR4) ligand lipopolysaccharides (LPS), we were able to examine the role of bacterial infection in SLE. In our study, the transgenic mice with a secreted form of anti-dsDNA were found to have higher levels of anti-nuclear antibodies, anti-dsDNA, blood urea nitrogen, and proteinuria. The splenocytes of the mice stimulated with LPS secreted more anti-dsDNA, IFN-γ, and IL-10. After injecting them with LPS in vivo, we further found higher immune complex depositions and IL-10 in the kidneys of the transgenic mice. Moreover, the LPS-injected transgenic mice had higher mortality rate. This is the first transgenic model to demonstrate that only 2 risk factors, pathogenic anti-dsDNA and TLR4 activation, induce severe SLE syndromes in normal mice through the overproduction of IL-10 and IFN-γ. These findings imply that anti-dsDNA and bacterial infections have pivotal roles in the pathogenesis of SLE; the inhibition of TLR4 may be regarded as a therapeutic target.

Defensins in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease, resulting in inflammation and tissue damage. The precise etiology for SLE is so far unknown. It has been shown that the innate immunity plays a role in SLE pathogenesis. The innate immune system confers broad protection against pathogens by the secretion of broad-spectrum antibacterial and immunomodulatory substances named defensins. Recently, alpha-defensin, the products of neutrophils have been found to be upregulated at the mRNA and protein levels in SLE patients. In addition, increased antidefensin antibodies were found in sera of patients with SLE, but these levels decreased after therapy with corticosteroids. These recent findings suggest a role for defensins in the pathogenesis of SLE. Thus, activation and degranulation of neutrophils leads to alpha-defensin secretion in SLE patients. Given their immunomodulatory role, alpha-defensin secretion might activate the adaptive immune system leading to the stimulation of the immune system, as is manifested in SLE.

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.

High circulating levels of free interleukin-18 in patients with active SLE in the presence of elevated levels of interleukin-18 binding protein

Systemic Lupus Erythematosus (SLE) is an autoimmune disease characterized by the production of autoantibodies particularly to nuclear antigens and by an abnormal production of proinflammatory cytokines. In the present study, we measured the levels of the proinflammatory cytokine IL-18 and its natural inhibitor, the IL-18 binding protein (IL-18BP), in sera of SLE patients at various stages of the disease. This is the first study to present IL-18BP levels in sera of SLE patients as well as the calculated, biologically active, free IL-18 concentrations that are most probably more relevant to the pathology of SLE. Sera from 48 unselective SLE patients (total of 195 samples) were obtained longitudinally with a mean follow-up period of 11.1 +/- 8.9 years and were compared to sera from 100 healthy volunteers. Circulating levels of IL-18, IL-18BP and free IL-18 in the SLE patients were significantly higher than the levels of healthy controls (5 fold, 6 fold and 3 fold for IL-18, IL-18BP and free IL-18, respectively) and correlated with disease activity as scored by SLEDAI-2K. Furthermore, these levels during active disease (SLEDAI-2K > or = 6) were higher compared to the levels measured in the sera of the same patients during remission or during mild disease (SLEDAI-2K 0-5). The high levels of IL-18 and IL-18BP in sera of active SLE patients suggest their possible role in the pathogenesis and course of the disease. However, despite the elevated levels of IL-18BP during active disease, free IL-18 remained more than 2 fold higher than the levels in healthy controls suggesting a potential benefit of administration of exogenous IL-18BP as a novel therapeutic approach for active SLE.

High alpha-defensin levels in patients with systemic lupus erythematosus

Innate immunity plays a role in systemic lupus erythematosus (SLE). Our objective was to determine the levels of defensins, which are antimicrobial and immunomodulatory polypeptides, in SLE. Sera from SLE patients and healthy controls were tested for pro-inflammatory human beta-defensin 2 (hBD-2) and for alpha-defensin human neutrophil peptide 1 (HNP-1). hBD-2 could not be detected by enzyme-linked immunosorbent assay (ELISA) and its mRNA levels were low in SLE patients and similar to those found in controls. In contrast, the mean alpha-defensin level in the sera of all SLE patients (11.07 +/- 13.92 ng/microl) was significantly higher than that of controls (0.12 +/- 0.07 ng/microl). Moreover, 60% of patients demonstrated very high serum levels (18.5 +/- 13.36 ng/microl) and 50% showed elevated gene expression in polymorphonuclear cells. High alpha-defensin levels correlated with disease activity, but not with neutrophil count. Thus, activation and degranulation of neutrophils led to alpha-defensin secretion in SLE patients. Given the immunomodulatory role of alpha-defensins, it is possible that their secretion may activate the adaptive immune system leading to a systemic response.

Intrarenal cytokine gene expression in lupus nephritis

BACKGROUND

Lupus nephritis is characterised by intrarenal inflammation and lymphocyte activation.

AIM

To examine the profile of cytokine gene expression in glomerulus and tubulointerstitium in patients with lupus nephritis.

METHODS

36 consecutive patients with systemic lupus erythematosus having active renal disease were recruited, and they were required to undergo kidney biopsy. Glomerular and tubulointestitial cytokine expression of interleukin (IL)2, 4, 10, 12, 18, interferon gamma (IFN)gamma, T-bet (the Th1 transcription factor), GATA-3 (the Th2 transcription factor), transforming growth factor beta and monocyte chemoattractant protein (MCP)1 were studied by laser microdissection of the renal biopsy specimen, followed by real-time quantitative PCR.

RESULTS

There were 13 patients with World Health Organization class III nephritis, 14 patients with class IV nephritis and 9 patients with class V nephritis. There was a significant correlation between serum C3, C4 and anti-double strand DNA antibody level with glomerular expression of T-bet, IFNgamma and IL2. There was a significant correlation between histological activity index and glomerular expression of IL12, IL18, IL10 and MCP1. In addition, the degree of glomerular leucocyte infiltration significantly correlated with glomerular expression of IFNgamma, IL10, IL12 and IL18. By contrast, histological chronicity index correlated with the tubulointerstitial expression of IL2, MCP1 and GATA-3.

CONCLUSIONS

Intraglomerular expression of certain target genes correlate with the severity of systemic as well as histological activity, whereas the tubulointerstitial expression of other target genes correlate with the degree of chronic kidney scarring. This result may shed light on the immunopathogenesis of lupus nephritis.

Interleukin-18 Promoter Gene Polymorphisms in Chinese Patients With Systemic Lupus Erythematosus: Association With CC Genotype at Position –607

Introduction: Interleukin-18 (IL-18) is a Th1 cytokine, which is postulated to play a role in systemic lupus erythematosus (SLE). Two single nucleotide polymorphisms (SNPs) in the IL-18 promoter gene region were found to influence the quantitative expression of the IL-18 protein. The aim of this study was to determine whether IL-18 promoter gene polymorphisms are associated with SLE. Materials and Methods: One hundred and thirteen Chinese SLE patients and 218 Chinese healthy individuals were recruited. Genomic DNA was extracted from peripheral venous blood. Sequence-specific primer PCR and restriction fragment length polymorphism (RFLP) analysis were used to genotype the DNA samples for SNP-137 and SNP- 607. The following genotypes were obtained: SNP(-607) AA, AC, CC and SNP(-137) GG, GC, CC. Plasma IL-18 concentrations of patients and control subjects were measured by enzyme-linked immunosorbent assay. Results: the frequency of SNP-607/CC genotype was significantly higher in SLE patients (Pc < 0.05) while genotype SNP-607/AC was significantly decreased in SLE patients compared to the control group (Pc <0.05). Plasma IL-18 concentrations were significantly higher in SLE patients than in control subjects (P <0.05). Both patients and control subjects with CC and AC genotypes have significantly higher IL-18 concentrations than those with AA genotype. Conclusion: The IL-18 promoter gene polymorphism SNP–607 C allele is associated with SLE and may result in the enhanced production of IL-18 protein in SLE and normal individuals. Key words: Cytokines, Genotype, Single nucleotide polymorphisms

Correlation between levels of TNF-alpha and IL-6 and hematological involvement in SLE Egyptian patients with lupus nephritis

BACKGROUND

Systemic lupus Erythematosus (SLE) is a rheumatic autoimmune disease characterized by multisystem organ involvement and by high titers of auto antibodies against several nuclear and cytoplasmic antigens. Numerous abnormalities of the cytokine network have been described in patients suffering from SLE. However the role of cytokines in different organ involvement is not yet well defined.

OBJECTIVE

To determine if levels of Interlukin-6 (IL-6) and Tumor necrosis factor (TNF-alpha) correlate with SLE disease activity in Egyptian SLE patients and more specifically with hematological involvement.

METHODS

Levels of TNF-alpha and IL-6 in serum samples from sixty individuals (40 with Systemic lupus Erythmatosus and 20 healthy controls) were determined and renal biopsies were obtained from SLE patients.

RESULTS

Levels of TNF-alpha and IL-6 were higher in SLE patients with active compared with inactive hematological disease. Further analysis showed that this association was dependent on inverse correlation (P=0.017, r=-0.49) for IL-6 and (P=0.76, r=-.243) for TNF-alpha. The mean level of TNF-alpha and Il-6 was (766.95+/-357.82 pg/ml) and (135.4+/-54.23 pg/ml) respectively for patients with active disease while it was (314.01+/-100.87 pg/ml) and (47.33+/-18.61 pg/ml) for those with inactive disease and (172.7+/-39.19 pg/ml) and (21.15+/-10.99 pg/ml) for the healthy control group respectively. The difference was statistically significant (P=0.002). We found significant positive correlations between TNF-alpha and IL-6 and the SLE Disease Activity Index (SLEDAI) score. (r=+0.743 and +0.772 respectively).

CONCLUSION

Raised level of Il-6 and TNF-alpha may influence the development of anemia in Egyptian patients with Lupus Nephritis.

Urinary mononuclear cell and disease activity of systemic lupus erythematosus

Mononuclear cells play a cardinal role in the pathogenesis of systemic lupus erythematosus (SLE). A high urine cytology score has been reported to be associated with lupus nephritis in relapse. The objective of this study was to examine the urinary mononuclear cell population of patients with lupus nephritis, and explore its correlation with lupus disease activity. We studied 12 patients with active lupus nephritis, 17 patients with lupus nephritis in remission, 12 SLE patients with no history of renal disease and 13 healthy subjects. Clinical disease activity was quantified by the SLE Disease Activity Index (SLEDAI). Mononuclear cell species in the urinary sediment were examined by immunocytochemistry. Patients with active lupus nephritis had significantly more mononuclear cells in the urinary sediment. The number of CD3+ cell was significantly elevated in the active lupus nephritis than the others (P < 0.001), while there was no significant difference in the number of CD20+ and CD56+ cell among patient groups. The total urinary mononuclear cell correlated significantly with the overall SLEDAI score (r = 0.58, P < 0.001) as well as the renal score (r = 0.57, P < 0.001). The number of urinary CD3+, but not CD20+ or CD56+, cell significantly correlated with the overall SLEDAI score (r = 0.46, P = 0.003) as well as the renal score (r = 0.40, p = 0.011). In nine patients with renal biopsy, the histological activity index correlated with the total urinary mononuclear cell (r = 0.75, P = 0.02), CD3+ (r = 0.69, P = 0.04) and CD20+ cell (r = 0.69, P = 0.04). We conclude that urinary mononuclear cell was markedly elevated in patients with active lupus, and the urinary mononuclear cell count correlated significantly with the SLEDAI score and histological activity. CD3+ and CD20+ cells are the major component of urinary mononuclear cell in SLE patients and their number correlates with lupus disease activity.

Imbalance of Th1/Th2 transcription factors in patients with lupus nephritis

OBJECTIVE

Systemic lupus erythematosus (SLE) is characterized by the aberrant activation of T lymphocytes. Since T-bet and GATA-3 are the principal transcription factors for the differentiation of type-1 and type-2 helper T lymphocytes, respectively, we studied their mRNA expression in the urinary sediment of SLE patients and compared this with their urinary and intra-renal protein expression.

METHODS

We studied 100 SLE patients and 10 healthy subjects. Urinary mRNA expression of T-bet and GATA-3 were studied by the real-time quantitative polymerase chain reaction. Intra-renal and urinary expressions of T-bet and GATA-3 were studied by immunohistochemistry and western blotting, respectively.

RESULTS

The urinary mRNA and protein expressions of T-bet were significantly higher in SLE patients with active nephritis than those with inactive disease (mRNA: P < 0.001; protein: P = 0.004). The urinary mRNA expression of T-bet correlated with the SLE disease activity index (SLEDAI) score (r = 0.55, P < 0.001) and the histological activity index (r = 0.48, P = 0.03). On the other hand, the urinary mRNA and protein expressions of GATA-3 were significantly lower in SLE patients with active nephritis (mRNA: P < 0.001; protein: P = 0.006), and GATA-3 mRNA expression inversely correlated with the SLEDAI score (r = 0.38, P < 0.001). For the 22 SLE patients with kidney biopsy, tubular expressions of T-bet and GATA-3 significantly correlated with the histological activity index (T-bet: r = 0.57, P = 0.006; GATA-3: r = -0.79, P < 0.001).

CONCLUSIONS

Patients with active lupus nephritis have increased T-bet and depressed GATA-3 expression in the urinary sediment and kidney tissue, indicating a predominant Th1 type of T-lymphocyte activation.

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.

Elevated interleukin-18 levels correlated with disease activity in systemic lupus erythematosus

The aim of this study was to determine the serum interleukin-18 (IL-18) levels in patients with systemic lupus erythematosus (SLE) and to assess their relationship with disease activity. Thirty-five patients with SLE and 35 age- and sex-matched controls were enrolled in this study. Paired serum samples were collected from all the patients with SLE, both at active stage before treatment and at the stable stage after treatment. The serum IL-18 levels were determined using ELISA and their correlations with the disease activity, measured using the SLE Disease Activity Index (SLEDAI) and laboratory parameters such as anti-dsDNA antibody, CH50, C3, C4, and circulating immune complex levels, were analyzed. The serum IL-18 levels in patients with SLE were significantly higher than those in the controls, particularly when the disease status was active (mean+/-SD: active stage, 721.23+/-360.15 pg/ml; inactive stage, 343.68+/-317.78 pg/ml; controls, 113.98+/-13.22 pg/ml, p<0.05). The IL-18 levels measured at the active stage before treatment correlated well with SLEDAI (r=0.41, p<0.05) and anti-dsDNA antibody titer (r=0.35, p<0.05). When we compared the changes of the IL-18 level and those of parameters reflecting the disease activity between the active stage and the stable stage of the disease, it was found that the changes in IL-18 level correlated well with the changes of SLEDAI score during the patient's disease course (r=0.39, p<0.05). In conclusion, the serum IL-18 levels were elevated in patients with SLE, and these increased levels correlated well with SLE disease activity.

T cell help is required to induce idiotypic-anti-idiotypic autoantibody network after immunization with complementary epitope 289-308aa of La/SSB autoantigen in non-autoimmune mice

Immunotherapies against autoimmune diseases have been of limited success. Preventive vaccines could be developed on the basis to abrogate unwanted immune responses to defined autodeterminants. In this study it is shown that immunization of BALB/c mice with two linear T and B cell epitopes of the human La/SSB autoantigen (spanning the regions 289-308aa and 349-364aa) and their complementary forms specified by the complementary mRNA, results in characteristic B and T cell responses. Mice immunized with the 289-308aa epitope or its complementary peptide elicited specific antibodies against both epitopes. In contrast, mice immunized with the 349-364aa epitope or its complementary peptide mounted antibody titres against the immunizing peptide only. According to these data, the 289-308aa epitope and its complementary form were capable to generate an idiotypic-anti-idiotypic response, which were cross-regulated. Peptide-specific T cell proliferation and cytokine production in vitro revealed the induction of a two-stage T helper response (Th1-->Th2 type) after immunization with either the epitope 289-308 or its complementary peptide. IgG1 was the predominant subclass after immunization with the two forms of epitopes 289-308 and 349-364, while a response of the IgG2b > IgG2a was obtained after the immunization with the complementary form of 349-364 epitope reflecting the TH2/TH1 polarization, respectively. Our data suggest that the complementary peptides of two immunodominant epitopes of human LaSSB can mimic the autoantibodies against these epitopes and establish an active idiotypic-anti-idiotypic network.

Decreased production of interleukin-12 and interferon-gamma is associated with renal involvement in systemic lupus erythematosus

OBJECTIVE

To analyze the type 1/type 2 cytokine balance in patients with systemic lupus erythematosus (SLE) according to the presence of renal disorder and activity status.

METHODS

We measured the serum levels of type 1 (IFN-gamma, IL-12) and type 2 cytokines (IL-4, IL-10) as well as spontaneous and stimulated cytokine production from peripheral blood mononuclear cells (PBMC) in 40 patients with SLE.

RESULTS

Patients with lupus nephritis (LN) showed significantly lower levels of serum IL-12 and IFN-gamma than those without LN. Production of IL-12 and IFN-gamma by stimulated PBMC were also decreased in patients with LN. The circulating IL-12 correlated positively with IFN-gamma, but inversely with IL-10. The SLEDAI scores correlated well with the ratio of IL-4/IFN-gamma levels.

CONCLUSION

The reduced production of IL-12 and IFN-gamma and the resultant shift towards the type 2 cytokine phenotype may be associated with LN.

Suppression of experimental systemic lupus erythematosus (SLE) in mice via TNF inhibition by an anti-TNFalpha monoclonal antibody and by pentoxiphylline

We have previously shown that the clinical manifestations of experimental systemic lupus erythematosus (SLE) correlate with an early increased secretion of TNFalpha and IL-1. In the present study, we examined the efficacy of two therapeutic modalities which lower TNFalpha production or activity, on the clinical manifestations of the disease. Experimental SLE was induced in naive C3H.SW mice by injection of the human anti-DNA monoclonal antibody (mAb) bearing the common idiotype, 16/6 Id. Two weeks after booster injections, treatment with either an anti-TNFalpha mAb, or pentoxiphylline (PTX) was started, for a period of 6 weeks. Production of TNFalpha (by splenocytes) and IL-1 (by peritoneal macrophages) was determined 3 and 7 months after disease induction. The experimental mice were also followed for disease manifestations. Both treatment protocols, with anti-TNFalpha mAb and with PTX, reduced the production of the two pro-inflammatory cytokines. TNFalpha and IL-1, in mice with experimental SLE. Anti-DNA antibodies were significantly lower in the mice treated with either protocol. In addition, a significantly lower rate of leukopenia, proteinuria and immune complex deposition was observed in treated mice. Abrogation of TNFalpha and IL-1 production in the early stages of experimental SLE by an anti-TNFalpha mAb or by PTX improves the clinical status of mice afflicted with this autoimmune disease.

Imbalance between interleukin-6 and adrenomedullin mRNA levels in peripheral blood mononuclear cells of patients with lupus nephritis

In this study, we measured the mRNA levels of adrenomedullin (AM), C-type natriuretic peptide, vascular endothelial growth factor, interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) in peripheral blood mononuclear cells (PBMC) of 34 patients with lupus nephritis (LN) (15 active and 19 inactive) and 30 healthy volunteers. mRNA levels were measured using a real-time quantitative PCR METHOD: Compared with healthy volunteers, IL-6 mRNA levels were elevated in LN patients (P < 0.005), while AM mRNA levels were decreased (P < 0.05). Also, IL-6 mRNA levels were higher and AM mRNA levels lower in active LN patients compared with inactive LN patients. In addition, IL-6 mRNA levels positively correlated and AM mRNA levels negatively correlated with SLE disease activity index and laboratory findings, such as blood urea nitrogen, serum creatinine, 50% haemolytic unit of complement and urinary excretion of protein over 24 h. Furthermore, IL-6 mRNA levels were negatively correlated with AM mRNA levels within the same LN patients. With regard to pathological findings, our results showed that IL-6 mRNA levels were higher, and AM mRNA levels significantly lower in patients with a high activity index compared to those with a low activity index. Following treatment with prednisolone, IL-6 mRNA levels in active LN patients decreased and AM mRNA levels increased to levels comparable to those in inactive LN and healthy volunteers. In vitro studies further demonstrated that elevated IL-6 mRNA levels in active LN patient PBMC were suppressed by the addition of adrenomedullin. Our results suggest that an imbalance between IL-6 and AM levels may play an important role in the progression of SLE, and that the mRNA levels of these genes in PBMC may be used as a disease activity index for SLE.

Lupus nephritis: lessons from experimental animal models

Lupus nephritis is a frequent and severe complication of SLE. In the last decades, animal models for SLE have been studied widely to investigate the immunopathology of this autoimmune disease because abnormalities can be studied and manipulated before clinical signs of the disease become apparent. In this review an overview is given of our current knowledge on the development of lupus nephritis, as derived from animal models, and a hypothetical pathway for the development of lupus nephritis is postulated. The relevance of the studies in experimental models in relationship with our knowledge of human SLE is discussed.

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.

Elevation of plasma interleukin-18 concentration is correlated with disease activity in systemic lupus erythematosus

BACKGROUND

Previous studies have indicated that the autoimmune phenomenon might be caused by an imbalance of T-helper cell (Th) cytokines.

METHODS

We investigated the plasma concentrations of a novel pro-inflammatory Th1 cytokine, interleukin (IL)-18, and its inducer, IL-12, in patients with systemic lupus erythematosus (SLE) and correlated them with the SLE disease activity index (SLEDAI). Plasma IL-18 and IL-12 concentrations of 40 SLE patients and 18 sex- and age-matched control subjects were measured by enzyme-linked immunosorbent assay.

RESULTS

Plasma IL-18 and IL-12 concentrations were significantly higher in SLE patients than in control subjects [median (interquartile range): IL-18, 320.0 pg/ml (164.4-475.6 pg/ml) vs 130.1 pg/ml (57.8-202.4 pg/ml), P<0.001; IL-12, 143.3 pg/ml (39.4-247.2 pg/ml) vs. 84.7 pg/ml (29.3-140.1 pg/ml), P<0.001]. Increases in IL-18 concentration correlated positively and significantly with SLEDAI score (r = 0.449, P = 0.004).

CONCLUSION

The novel cytokine IL-18 might play a crucial role in triggering the inflammatory processes in SLE.

Role of perforin in controlling B-cell hyperactivity and humoral autoimmunity

To determine the role of perforin-mediated cytotoxic T lymphocyte (CTL) effector function in immune regulation, we studied a well-characterized mouse model of graft-versus-host disease (GVHD). Induction of acute GVHD using perforin-deficient donor T cells (pfp-->F1) initially resulted in features of acute GVHD, e.g., engraftment of both donor CD4(+) and CD8(+) T cells, upregulation of Fas and FasL, production of antihost CTL, and secretion of both Th1 and Th2 cytokines. Despite fully functional FasL activity, pfp donor cells failed to totally eliminate host B cells, and, by 4 weeks of disease, cytokine production in pfp-->F1 mice had polarized to a Th2 response. Pfp-->F1 mice eventually developed features of chronic GVHD, such as increased numbers of B cells, persistence of donor CD4 T cells, autoantibody production, and lupuslike renal disease. We conclude that in the setting of B- and T-cell activation, perforin plays an important immunoregulatory role in the prevention of humoral autoimmunity through the elimination of both autoreactive B cells and ag-specific T cells. Moreover, an ineffective initial CTL response can evolve into a persistent antibody-mediated response and, with it, the potential for sustained humoral autoimmunity.

Effect of aging on cytokine production in normal and experimental systemic lupus erythematosus-afflicted mice

Aging mice of strains susceptible to the induction of experimental systemic lupus erythematosus (SLE) develop a milder disease than young animals. To find out whether the decrease in susceptibility to disease is due to age-associated changes in cytokine profile, we first examined the secretion of cytokines by healthy mice aged 2-15 months. A gradual age-related decline in the levels of interleukin (IL)-2 and interferon (IFN) gamma, and an increase in IL-4, IL-10, IL-1, and tumor necrosis factor (TNF) alpha were observed. Experimental SLE was induced in 2- and 10-month-old mice by immunization with the monoclonal anti-DNA antibody bearing the 16/6 Id. Early increased production of pro-inflammatory cytokines (TNFalpha and IL-1), followed by a peak of the Th1-type cytokines (IL-2, IFNgamma) were observed in young mice. The Th2-type cytokines (IL-4, IL-10) peaked later. In contrast, only a mild increase in all of the above cytokines was determined in 10-month immunized mice. It thus appears that the decline in susceptibility to SLE induction in older mice may be related to changes in the capacity to produce cytokines.

Modulation of autoimmune disease in the MRL-lpr/lpr mouse by IL-2 and TGF-beta1 gene therapy using attenuated Salmonella typhimurium as gene carrier

We have investigated the effects of interleukin-2 (IL-2) and transforming growth factor-beta (TGF-beta) gene therapy on the progress of autoimmune disease in MRL-lpr/lpr mice, a murine model of systemic lupus erythematosus (SLE). These mice have uncontrolled proliferation of T cells, an impaired response to T cell mitogen and produce autoantibodies against nuclear antigens, including DNA. Immune complexes formed by these autoantibodies are believed to cause glomerulonephritis and vasculitis in lupus mice and human SLE. Since there is an imbalance of cytokine production in both SLE patients and lupus mice, we examined the effects of cytokine gene therapy on the progression of autoimmune disease in MRL-lpr/lpr mice. The mice were treated orally with a non-pathogenic strain of Salmonella typhimurium bearing the aroA-aroD- mutations and carrying the murine genes encoding IL-2 and TGF-beta. The bacteria synthesise and slowly release the cytokines in vivo. Our results show that, contrary to expectation, TGF-beta gene therapy produced no improvement in pathology and generally had opposite effects to those of IL-2. IL-2 gene therapy restored the defective T cell proliferative response to mitogen and suppressed the autoantibody response, glomerulonephritis and growth of lymphoid tumours.

Decreased production of interleukin-12 and other Th1-type cytokines in patients with recent-onset systemic lupus erythematosus

OBJECTIVE

To determine the profile of Th1-type and Th2-type cytokines produced by mononuclear cells from patients with recent-onset systemic lupus erythematosus (SLE), prior to the initiation of treatment with corticosteroids.

METHODS

Using sensitive radioimmunoassays, interleukin-4 (IL-4), IL-10, IL-12 p40, tumor necrosis factor alpha (TNF alpha), interferon-gamma (IFN gamma), and granulocyte-macrophage colony-stimulating factor (GM-CSF) released into the culture supernatants of various unstimulated and stimulated blood mononuclear cell populations from 10 SLE patients was assessed in comparison with 10 matched healthy controls studied in parallel.

RESULTS

In early SLE, monocyte-enriched cells constitutively produced increased amounts of IL-10 and decreased amounts of IL-12 following stimulation. Lymphocyte-enriched cells in SLE produced decreased amounts of IFN gamma and TNF alpha following stimulation. In "rested" cells, these defects were accentuated and a defect in IL-12 production was suggested. Depletion studies suggested that CD8+ cells were a major source of TNF alpha and IFN gamma in controls, but not in SLE patients. Increased IL-4 production or abnormalities in GM-CSF production were not observed.

CONCLUSION

This study suggests that even early in the course of SLE, monocyte production of IL-10 is increased and that of IL-12 is decreased. Decreased production of Th1-type cytokines in SLE may be secondary to this imbalance between IL-10 and IL-12. A contributory role of dysfunctional CD8+ cells is suggested.

The immunoregulatory effects of NK cells: the role of TGF-beta and implications for autoimmunity

The cytotoxic activities of natural killer (NK) cells--important in innate immunity--have received considerable attention, but NK cells also regulate T- and B-cell functions as well as hematopoiesis. Here, David Horwitz and colleagues focus on the capacity of NK cells to regulate antibody production positively and negatively, and in particular on the role of NK-cell transforming growth factor beta (TGF-beta) in downregulation of B-cell activity.

Effect of aging on cytokine production in normal and experimental systemic lupus erythematosus afflicted mice

The objective of the this study was to determine the cytokine profile of aging mice and to establish whether changes in cytokine production account for the fact that aging mice develop a milder disease than the young in response to induced experimental systemic lupus erythematosus (SLE). Cytokine secretion was evaluated in groups of BALB/c and C3H.SW mice at different ages between 2 and 24 months. The production of IL-2, IL-4, IL-10, IFN gamma and TNF alpha was determined in supernatants of ConA-stimulated splenocytes and that of IL-1 in the supernatants of LPS-stimulated peritoneal macrophages. A gradual age-related decline was observed in the production of IL-2 and IFN gamma, whereas the levels of IL-4, IL-10, IL-1 and TNF alpha progressively increased with aging, in unimmunized BALB/c and C3H.SW mice. Experimental SLE was induced in 2 and 10 month old C3H.SW mice by immunization with the monoclonal anti-DNA antibody bearing the 16/6 Id. The characteristic cytokine profile following immunization of 2 month old mice was early increased production of TNF alpha and IL-1, followed by a peak of Th1 type cytokines (IL-2, IFN gamma). At a later stage of the disease, a peak of Th2 type cytokines (IL-4, IL-10) was observed that was concomitant with low levels of Th1 cytokines. In contrast, in the 10 month old mice that were immunized with 16/6 Id only a mild increase in all the above cytokines was observed. We suggest that the lower autoantibody production and moderate clinical manifestations in aging mice with experimental SLE are causally related to the decreased production of pro-inflammatory cytokines at the initial stages of the disease followed by a lower production of both Th1 and Th2 type cytokines.