Interleukin 2 and systemic lupus erythematosus

De novo design of mini-binder proteins against IL-2 receptor β chain

IL-2 regulates the immune response by interacting with different IL-2 receptor (IL-2R) subunits. High dose of IL-2 binds to IL-2Rβγc heterodimer, which induce various side effects while activating immune function. Disrupting IL-2 and IL-2R interactions can block IL-2 mediated immune response. Here, we used a computational approach to de novo design mini-binder proteins against IL-2R β chain (IL-2Rβ) to block IL-2 signaling. The hydrophobic region where IL-2 binds to IL-2Rβ was selected and the promising binding mode was broadly explored. Three mini-binders with amino acid numbers ranging from 55 to 65 were obtained and binder 1 showed the best effects in inhibiting CTLL-2 cells proliferation and STAT5 phosphorylation. Molecular dynamics simulation showed that the binding of binder 1 to IL-2Rβ was stable; the free energy of binder1/IL-2Rβ complex was lower, indicating that the affinity of binder 1 to IL-2Rβ was higher than that of IL-2. Free energy decomposition suggested that the ARG35 and ARG131 of IL-2Rβ might be the key to improve the affinity of binder. Our efforts provided new insights in developing of IL-2R blocker, offering a potential strategy for ameliorating the side effects of IL-2 treatment.

The star target in SLE: IL-17

PURPOSE

The purpose of this review is to discuss the significance of IL-17 in SLE and the potential of IL-17-targeted therapy.

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disease that can affect many organs and tissues throughout the body. It is characterized by overactive B and T cells and loss of immune tolerance to autoantigens. Interleukin-17 (IL-17) is a cytokine that promotes inflammation and has been implicated in the pathogenesis of several autoimmune diseases as well as inflammatory diseases. In in vitro cellular experiments in lupus susceptible mice or SLE patients, there is substantial evidence that IL-17 is a highly promising therapeutic target.

METHODS

We searched papers from PubMed database using the search terms, such as interleukin-17, systemic lupus erythematosus, treatment targets, T cells, lupus nephritis, and other relevant terms.

RESULTS

We discuss in this paper the molecular mechanisms of IL-17 expression, Th17 cell proliferation, and the relationship between IL-17 and Th17. The significance of IL-17 in SLE and the potential of IL-17-targeted therapy are further discussed in detail.

CONCLUSION

IL-17 has a very high potential for the development as a star target in SLE.

Decreased SUV39H1 at the promoter region leads to increased CREMα and accelerates autoimmune response in CD4+ T cells from patients with systemic lupus erythematosus

BACKGROUND

Overproduction of cAMP-responsive element modulator α (CREMα) in total T cells from patients with systemic lupus erythematosus (SLE) can inhibit IL-2 and increase IL-17A. These ultimately promote progression of SLE. This study aims to investigate the expression of CREMα in SLE CD4⁺ T cells and find out the mechanisms for the regulation of CREMα in SLE CD4⁺ T cells.

RESULTS

CREMα mRNA was overexpressed in CD4⁺ T cells from SLE patients. The levels of histone H3 lysine 9 trimethylation (H3K9me3) and suppressor of variation 3-9 homolog 1 (SUV39H1) at the CREMα promoter of SLE CD4⁺ T cells were markedly decreased. Down-regulating SUV39H1 in normal CD4⁺ T cells elevated the levels of CREMα, IL-17A, and histone H3 lysine 4 trimethylation (H3K4me3) in the CREMα promoter region, and lowered IL-2, H3K9me3, DNA methylation, and DNA methyltransferase 3a (DNMT3a) enrichments within the CREMα promoter, while no sharp change in SET domain containing 1 (Set1) at the CREMα promoter. Up-regulating SUV39H1 in SLE CD4⁺ T cells had the opposite effects. The DNA methylation and DNMT3a levels were obviously reduced, and H3K4me3 enrichment was greatly increased at the CREMα promoter of CD4⁺ T cells from SLE patients. The Set1 binding in the CREMα promoter region upgraded significantly, and knocking down Set1 in SLE CD4⁺ T cells alleviated the H3K4me3 enrichment within this region, suppressed CREMα and IL-17A productions, and promoted the levels of IL-2, CREMα promoter DNA methylation, and DNMT3a. But there were no obviously alterations in H3K9me3 and SUV39H1 amounts in the region after transfection.

CONCLUSIONS

Decreased SUV39H1 in the CREMα promoter region of CD4⁺ T cells from SLE patients contributes to under-expression of H3K9me3 at this region. In the meantime, the Set1 binding at the CREMα promoter of SLE CD4⁺ T cells is up-regulated. As a result, DNMT3a and DNA methylation levels alleviate, and H3K4me3 binding increases. All these lead to overproduction of CREMα. Thus, the secretion of IL-2 down-regulates and the concentration of IL-17A up-regulates, ultimately promoting SLE.

Insufficient Iron Improves Pristane-Induced Lupus by Promoting Treg Cell Expansion

Trace element iron affects T cell biology, but the knowledge about the role of iron in regulating Treg cell expansion is limited. Treg cells play an important role in keeping peripheral T cell tolerance, increasing Treg cell expansion is a promising therapeutic method for SLE. Here we showed that iron deficiency promotes Treg cell expansion by reducing ROS accumulation, improving the disease progression of pristane-induced lupus. Increased oxidative stress inhibits Treg cell differentiation by inducing cell apoptosis. Our data suggest that altering iron metabolism promotes Treg cell expansion by preventing oxidation-induced cell death, which may provide a potential therapeutic strategy for SLE.

Potential for Antigen-Specific Tolerizing Immunotherapy in Systematic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic complex systemic autoimmune disease characterized by multiple autoantibodies and clinical manifestations, with the potential to affect nearly every organ. SLE treatments, including corticosteroids and immunosuppressive drugs, have greatly increased survival rates, but there is no curative therapy and SLE management is limited by drug complications and toxicities. There is an obvious clinical need for safe, effective SLE treatments. A promising treatment avenue is to restore immunological tolerance to reduce inflammatory clinical manifestations of SLE. Indeed, recent clinical trials of low-dose IL-2 supplementation in SLE patients showed that in vivo expansion of regulatory T cells (Treg cells) is associated with dramatic but transient improvement in SLE disease markers and clinical manifestations. However, the Treg cells that expanded were short-lived and unstable. Alternatively, antigen-specific tolerance (ASIT) approaches that establish long-lived immunological tolerance could be deployed in the context of SLE. In this review, we discuss the potential benefits and challenges of nanoparticle ASIT approaches to induce prolonged immunological tolerance in SLE.

Chronic Immune Activation in Systemic Lupus Erythematosus and the Autoimmune PTPN22 Trp620 Risk Allele Drive the Expansion of FOXP3+ Regulatory T Cells and PD-1 Expression

In systemic lupus erythematosus (SLE), perturbed immunoregulation underpins a pathogenic imbalance between regulatory and effector CD4⁺ T-cell activity. However, to date, the characterization of the CD4⁺ regulatory T cell (Treg) compartment in SLE has yielded conflicting results. Here we show that patients have an increased frequency of CD4⁺FOXP3⁺ cells in circulation owing to a specific expansion of thymically-derived FOXP3⁺HELIOS⁺ Tregs with a demethylated FOXP3 Treg-specific demethylated region. We found that the Treg expansion was strongly associated with markers of recent immune activation, including PD-1, plasma concentrations of IL-2 and the type I interferon biomarker soluble SIGLEC-1. Since the expression of the negative T-cell signaling molecule PTPN22 is increased and a marker of poor prognosis in SLE, we tested the influence of its missense risk allele Trp⁶²⁰ (rs2476601C>T) on Treg frequency. Trp⁶²⁰ was reproducibly associated with increased frequencies of thymically-derived Tregs in blood, and increased PD-1 expression on both Tregs and effector T cells (Teffs). Our results support the hypothesis that FOXP3⁺ Tregs are increased in SLE patients as a consequence of a compensatory mechanism in an attempt to regulate pathogenic autoreactive Teff activity. We suggest that restoration of IL-2-mediated homeostatic regulation of FOXP3⁺ Tregs by IL-2 administration could prevent disease flares rather than treating at the height of a disease flare. Moreover, stimulation of PD-1 with specific agonists, perhaps in combination with low-dose IL-2, could be an effective therapeutic strategy in autoimmune disease and in other immune disorders.

The role of IL-17 in systemic lupus erythematosus and its potential as a therapeutic target

INTRODUCTION

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibodies production and immune complex deposition with systemic clinical manifestations. Interleukin (IL)-17-producing cells play a crucial role in disease pathogenesis and represent an attractive therapeutic target. Areas covered: This review provides an update on the possibility of targeting IL-17 in SLE. The rational for this approach as well as currently available and future targets are discussed. Expert opinion: Although human expression studies and animal models indicate that IL-17 blocking may be a promising therapeutic strategy for SLE, direct evidence for IL-17 inhibition in SLE patients is unavailable. Biologic therapies and small-molecule drugs that target IL-17 production are required for the achievement of a favorable clinical effect in SLE patients.

Targeting Regulatory T Cells to Treat Patients With Systemic Lupus Erythematosus

Regulatory T cells (Tregs) are central in integration and maintenance of immune homeostasis. Since breakdown of self-tolerance is a major culprit in the pathogenesis of systemic lupus erythematosus (SLE), restoration of the immune tolerance through the manipulation of Tregs can be exploited to treat patients with SLE. New information has revealed that Tregs besides their role in suppressing the immune response are important in tissue protection and regeneration. Expansion of Tregs with low-dose IL-2 represents an approach to control the autoimmune response. Moreover, control of Treg metabolism can be exploited to restore or improve their function. Here, we summarize the function and diversity of Tregs and recent strategies to improve their function in patients with SLE.

[Effect of aberrant H3K27me3 modification in promoter regions on cAMP response element modulator α expression in CD4+ T cells from patients with systemic lupus erythematosus]

OBJECTIVE

Increased cAMP response element modulator α (CREMα) in T cells plays an essential role in the pathogenesis of systemic lupus erythematosus (SLE). The aim of this study was to investigate the mechanisms that elevates CREMα expression in SLE.

METHODS

CD4⁺ T cells from 5 healthy volunteers and 5 SLE patients were isolated for analysis of histone H3 lysine 27 trimethylation (H3K27me3) enrichment in different gene promoters using chromatin immunoprecipitation (ChIP) microarray. The levels of H3K27me3, H3K27 demethylases Jumonji domain containing 3 (JMJD3) and ubiquitously transcribed X (UTX), and H3K27 methyltransferase enhancer of zeste homolog 2 (EZH2) within the CREMα promoter were subsequently tested by ChIP and real?time PCR in CD4⁺ T cells from 30 normal controls and 30 SLE patients; CREMα mRNA level was also determined by real?time RT?PCR.

RESULTS

Analysis of ChIP microarray data identified that H3K27me3 enrichment at the CREMα promoter in CD4⁺ T cells from SLE patients was 0.23 times that of the normal control subjects. The results of ChIP and real?time PCR confirmed a marked decrease of H3K27me3 enrichment at the CREMα promoter in CD4⁺ T cells from SLE patients (P<0.001). The level of H3K27me3 at the promoter was negatively correlated with CREMα mRNA level in CD4⁺ T cells from SLE patients (P<0.001). In addition, a sharp increase was observed in JMJD3 binding at the CREMα promoter region in CD4⁺ T cells from SLE patients (P<0.001), and it was negatively correlated with H3K27me3 enrichment (P<0.001) and positively correlated with CREMα mRNA level (P<0.001). There were no significant changes in UTX (P=0.172) or EZH2 (P=0.281) binding at the CREMα promoter region in CD4⁺ T cells from SLE patients as compared to normal controls.

CONCLUSION

Increased JMJD3 binding down-regulates H3K27me3 enrichment at the CREMα promoter in CD4⁺ T cells of SLE patients to stimulate CREMα overexpression and result in the development of SLE.

Low-Dose IL-2 in the Treatment of Lupus

Recent extensive research on interleukin-2 (IL-2)/IL-2 receptor (IL-2R) biology has revealed its critical role in the regulation of immune tolerance by influencing regulatory T (Treg) cell functions and survival. Since in vivo low-dose IL-2 administration in humans has been confirmed to be safe and effective in expanding Treg, it is likely that it may be considered for the treatment of several autoimmune diseases including systemic lupus erythematousus (SLE). A recent clinical trial demonstrated the safety and efficacy of low-dose IL-2 treatment on SLE. In SLE, T cells show aberrant function such as deficient IL-2 production and abnormal signaling events. Expansion of Treg by IL-2 represents a specific strategy to control self-tolerance; however, restoration of abnormal immune function and responses should be addressed more carefully in patients with SLE considering the complexity of disease etiology and pathogenesis.

Increased Set1 binding at the promoter induces aberrant epigenetic alterations and up-regulates cyclic adenosine 5'-monophosphate response element modulator alpha in systemic lupus erythematosus

BACKGROUND

Up-regulated cyclic adenosine 5'-monophosphate response element modulator α (CREMα) which can inhibit IL-2 and induce IL-17A in T cells plays a critical role in the pathogenesis of systemic lupus erythematosus (SLE). This research aimed to investigate the mechanisms regulating CREMα expression in SLE.

RESULTS

From the chromatin immunoprecipitation (ChIP) microarray data, we found a sharply increased H3 lysine 4 trimethylation (H3K4me3) amount at the CREMα promoter in SLE CD4+ T cells compared to controls. Then, by ChIP and real-time PCR, we confirmed this result. Moreover, H3K4me3 amount at the promoter was positively correlated with CREMα mRNA level in SLE CD4+ T cells. In addition, a striking increase was observed in SET domain containing 1 (Set1) enrichment, but no marked change in mixed-lineage leukemia 1 (MLL1) enrichment at the CREMα promoter in SLE CD4+ T cells. We also proved Set1 enrichment was positively correlated with both H3K4me3 amount at the CREMα promoter and CREMα mRNA level in SLE CD4+ T cells. Knocking down Set1 with siRNA in SLE CD4+ T cells decreased Set1 and H3K4me3 enrichments, and elevated the levels of DNMT3a and DNA methylation, while the amounts of H3 acetylation (H3ac) and H4 acetylation (H4ac) didn't alter greatly at the CREMα promoter. All these changes inhibited the expression of CREMα, then augmented IL-2 and down-modulated IL-17A productions. Subsequently, we observed that DNA methyltransferase (DNMT) 3a enrichment at the CREMα promoter was down-regulated significantly in SLE CD4+ T cells, and H3K4me3 amount was negatively correlated with both DNA methylation level and DNMT3a enrichment at the CREMα promoter in SLE CD4+ T cells.

CONCLUSIONS

In SLE CD4+ T cells, increased Set1 enrichment up-regulates H3K4me3 amount at the CREMα promoter, which antagonizes DNMT3a and suppresses DNA methylation within this region. All these factors induce CREMα overexpression, consequently result in IL-2 under-expression and IL-17A overproduction, and contribute to SLE at last. Our findings provide a novel approach in SLE treatment.

Restoring regulation - IL-2 therapy in systemic lupus erythematosus

INTRODUCTION

The pathogenesis of systemic lupus erythematosus (SLE) involves an acquired deficiency of the cytokine IL-2, an essential growth and survival factor for regulatory T cells (Treg), which play an important role in the control of autoimmunity in SLE. In contrast to currently available therapies that broadly suppress the immune system, low-dose IL-2 therapy in SLE aims to compensate the pre-existing IL-2 deficiency and thus to restore a physiological state, where Treg can regain their ability to efficiently counteract autoimmunity. Areas covered: Here we summarize key findings that led to the development of this novel therapeutic concept and will highlight the key rationales for the clinical translation of low-dose IL-2 therapy in SLE. Expert commentary: The concept of low-dose IL-2 therapy in SLE has evolved from pathophysiological findings and thus can be considered a selective biological treatment strategy in SLE. Preliminary results from phase I/II studies are promising by proving selective Treg expansion and by providing first evidence for the clinical efficacy of low-dose IL-2 therapy in SLE.

T cells and IL-17 in lupus nephritis

Systemic lupus erythematosus (SLE) is a complicated autoimmune disorder characterized by autoantibodies production, immune complex formation, and immune dysregulation, resulting in damage of multiple organs including the kidney. Lupus nephritis (LN) is the most common severe manifestation of SLE involving the majority of patients. Even though there are a number of reports indicating that interleukin-17 (IL-17) and Th17 cells play important roles in the pathogenesis of LN, the precise molecular mechanisms underline the development of LN have not been totally elucidated. In this review, we briefly summarize general characteristics of T and IL-17 cells in SLE. In addition, we discuss in detail T cell signaling pathways which control IL-17 production in patients with LN and in glomerulonephritis in lupus-prone mice. A better understanding of signaling and gene regulation defects in LN will lead to the identification of novel therapeutic targets and predictive biomarkers for diagnosis and prognosis of this disease.

Cyclic AMP-Responsive Element Modulator α Polymorphisms Are Potential Genetic Risks for Systemic Lupus Erythematosus

To investigate whether the cyclic AMP-responsive element modulator α (CREMα) polymorphisms are novel susceptibility factors for systemic lupus erythematosus (SLE), four tag SNPs, rs1057108, rs2295415, rs11592925, and rs1148247, were genotyped in 889 SLE cases and 825 healthy controls. Association analyses were performed on whole dataset or clinical/serologic subsets. Association statistics were calculated by age and sex adjusted logistic regression. The G allele frequencies of rs2295415 and rs1057108 were increased in SLE patients, compared with healthy controls (rs2295415: 21.2% versus 17.8%, OR 1.244, P = 0.019; rs1057108: 30.8% versus 27.7%, OR 1.165, P = 0.049). The haplotype constituted by the two risk alleles “G-G” from rs1057108 and rs2295415 displayed strong association with SLE susceptibility (OR 1.454, P = 0.00056). Following stratification by clinical/serologic features, a suggestive association was observed between rs2295415 and anti-Sm antibodies-positive SLE (OR 1.382, P = 0.044). Interestingly, a potential protective effect of rs2295415 was observed for SLE patients with renal disorder (OR 0.745, P = 0.032). Our data provide first evidence that CREMα SNPs rs2295415 and rs1057108 maybe novel genetic susceptibility factors for SLE. SNP rs2295415 appears to confer higher risk to develop anti-Sm antibodies-positive SLE and may play a protective role against lupus nephritis.

T cell receptor-associated protein tyrosine kinases: the dynamics of tolerance regulation by phosphorylation and its role in systemic lupus erythematosus

There are different abnormalities that lead to the autoreactive phenotype in T cells from systemic lupus erythematosus (SLE) patients. Proximal signaling, involving the T-cell receptor (TCR) and its associated protein tyrosine kinases (PTKs), is significantly affected in SLE. This ultimately leads to aberrant responses, which include enhanced tyrosine phosphorylation and calcium release, as well as decreased IL-2 secretion. Lck, ZAP70 and Syk, which are PTKs with a major role in proximal signaling, all present abnormal functioning that contributes to an altered T cell response in these patients. A number of other molecules, especially regulatory proteins, are also involved. This review will focus on the PTKs that participate in proximal signaling, with specific emphasis on their relevance in maintaining peripheral tolerance, their abnormalities in SLE and how these contribute to an altered T cell response.

IL-2 protects lupus-prone mice from multiple end-organ damage by limiting CD4-CD8- IL-17-producing T cells

IL-2, a cytokine with pleiotropic effects, is critical for immune cell activation and peripheral tolerance. Although the therapeutic potential of IL-2 has been previously suggested in autoimmune diseases, the mechanisms whereby IL-2 mitigates autoimmunity and prevents organ damage remain unclear. Using an inducible recombinant adeno-associated virus vector, we investigated the effect of low systemic levels of IL-2 in lupus-prone MRL/Fas(lpr/lpr) (MRL/lpr) mice. Treatment of mice after the onset of disease with IL-2-recombinant adeno-associated virus resulted in reduced mononuclear cell infiltration and pathology of various tissues, including skin, lungs, and kidneys. In parallel, we noted a significant decrease of IL-17-producing CD3(+)CD4(-)CD8(-) double-negative T cells and an increase in CD4(+)CD25(+)Foxp3(+) immunoregulatory T cells (Treg) in the periphery. We also show that IL-2 can drive double-negative (DN) T cell death through an indirect mechanism. Notably, targeted delivery of IL-2 to CD122(+) cytotoxic lymphocytes effectively reduced the number of DN T cells and lymphadenopathy, whereas selective expansion of Treg by IL-2 had no effect on DN T cells. Collectively, our data suggest that administration of IL-2 to lupus-prone mice protects against end-organ damage and suppresses inflammation by dually limiting IL-17-producing DN T cells and expanding Treg.

Relationship between Serum Level of Interleukin-2 in Patients with Systemic Lupus Erythematosus and Disease Activity in Comparison with Control Group

BACKGROUND

Despite the large number of surveys, there are not any validated biomarkers for SLE disease activity till now. This study aimed to evaluate the relationship between serum level of IL-2 in patients with SLE and disease activity in comparison with control group.

MATERIALS AND METHODS

In this case-control study, 73 patients with lupus and 73 healthy subjects referred to the rheumatology clinic of 5 Azar Hospital in Gorgan (North of Iran).They were studied via convenience sampling during 2011-2012. Blood samples were taken from both groups and serum levels of interleukin -2 measured by Avi Bion Human IL-2 ELISA kit. Serum Level of IL-2 greater than 15 pg/ml defined positive and lesser than this amount defined negative. Disease activity evaluated with SLE disease activity index. Score greater than or equal to three or four defined as active disease. Data analysis conducted by SPSS software (version 16) and by using descriptive statistics and statistical tests.

RESULTS

Serum level of IL-2 was positive in 45.2% of sample studied and negative in 54.8% in case group, while in control group, serum level of IL-2 only in 11% of sample studied was positive and in 89% was negative. Statistical analysis indicated a significant relationship between serum level of IL-2 and the SLE disease activity index (p=0.025).

CONCLUSION

This study showed the relationship between serum levels of IL-2 and disease activity, so this biomarker can be used as a clinical indicator for assessing disease activity in patients with SLE.

The pathology of T cells in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterized by the production of a wide array of autoantibodies. Thus, the condition was traditionally classified as a "B-cell disease". Compelling evidence has however shown that without the assistance of the helper T lymphocytes, it is indeed difficult for the "helpless" B cells to become functional enough to trigger SLE-related inflammation. T cells have been recognized to be crucial in the pathogenicity of SLE through their capabilities to communicate with and offer enormous help to B cells for driving autoantibody production. Recently, a number of phenotypic and functional alterations which increase the propensity to trigger lupus-related inflammation have been identified in lupus T cells. Here, potential mechanisms involving alterations in T-cell receptor expressions, postreceptor downstream signalling, epigenetics, and oxidative stress which favour activation of lupus T cells will be discussed. Additionally, how regulatory CD4+, CD8+, and γδ T cells tune down lupus-related inflammation will be highlighted. Lastly, while currently available outcomes of clinical trials evaluating therapeutic agents which manipulate the T cells such as calcineurin inhibitors indicate that they are at least as efficacious and safe as conventional immunosuppressants in treating lupus glomerulonephritis, larger clinical trials are undoubtedly required to validate these as-yet favourable findings.

Identification of microRNA-31 as a novel regulator contributing to impaired interleukin-2 production in T cells from patients with systemic lupus erythematosus

OBJECTIVE

MicroRNAs (miRNAs) function to fine-tune the control of immune cell signaling. It is well established that there are abnormalities in the interleukin-2 (IL-2)-related signaling pathways in systemic lupus erythematosus (SLE). The miR-31 microRNA has been found to be markedly underexpressed in patients with SLE, and thus the present study was undertaken to investigate the role of miR-31 in IL-2 defects in lupus T cells.

METHODS

Expression levels of miR-31 were quantitated using TaqMan miRNA assays. Transfection and stimulation of cultured cells followed by TaqMan quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and reporter gene assays were conducted to determine the biologic function of miR-31. NF-AT nuclear translocation and expression were quantitatively measured using an ImageStream cytometer. Bioinformatics analysis, small interfering RNA (siRNA) knockdown, and Western blotting were performed to validate miR-31 targets and effects.

RESULTS

The expression of miR-31 was significantly decreased in lupus T cells, and this was positively correlated with the expression of IL-2. Overexpression of miR-31 in T cells increased the production of IL-2 by altering NF-AT nuclear expression and IL2 promoter activity, while knockdown of endogenous miR-31 reduced IL-2 production. RhoA expression was directly repressed by miR-31 in T cells. Of note, siRNA-mediated knockdown of RhoA enhanced IL2 promoter activity and, consequently, up-regulated IL-2 production. RhoA expression was consistently up-regulated and negatively correlated with the levels of miR-31 in lupus T cells. Manipulation of miR-31 expression in lupus T cells restored the expression of IL-2 at both the messenger RNA and protein levels.

CONCLUSION

MicroRNA-31 is a novel enhancer of IL-2 production during T cell activation. Dysregulation of miR-31 and its target, RhoA, could be a novel molecular mechanism underlying the IL-2 deficiency in patients with SLE.

Calcium/calmodulin-dependent protein kinase IV suppresses IL-2 production and regulatory T cell activity in lupus

The activity of calcium/calmodulin-dependent protein kinase IV (CaMK4) is increased in T cells from patients with systemic lupus erythematosus (SLE) and has been shown to reduce IL-2 production by promoting the effect of the transcriptional repressor cAMP responsive element modulator-α on the IL2 promoter. In this article, we demonstrate that T cells from MRL/lpr mice display increased levels of CaMK4 in the nucleus, and that genetic deletion of Camk4 results in improved survival. We demonstrate that absence of CaMK4 restores IL-2 production, curbs increased T cell activation, and augments the number and activity of regulatory T cells. Analogously, silencing of CaMK4 in T cells from patients with SLE increases the expression of FoxP3 on stimulation in the presence of TGF-β. Our results demonstrate the importance of the serine/threonine kinase CaMK4 in the generation and function of regulatory T cells in patients with SLE and lupus-prone mice, and its potential to serve as a therapeutic target.

Induction of the ‘ASIA’ syndrome in NZB/NZWF1 mice after injection of complete Freund’s adjuvant (CFA)

Adjuvants, commonly used in vaccines, may be responsible for inducing autoimmunity and autoimmune diseases, both in humans and mice. The so-called ‘ASIA’ (Autoimmune/inflammatory Syndrome Induced by Adjuvants) syndrome has been recently described, which is caused by the exposure to a component reproducing the effect of adjuvants. The aim of our study was to evaluate the effect of injection of complete Freund’s adjuvant (CFA) in NZB/NZWF1 mice, a lupus-prone murine model. We injected 10 NZB/NZWF1 mice with CFA/PBS and 10 with PBS, three times, 3 weeks apart, and followed-up until natural death. CFA-injected mice developed both anti-double-stranded DNA and proteinuria earlier and at higher levels than the control group. Proteinuria-free survival rate and survival rate were significantly lower in CFA-treated mice than in the control mice ( p = 0.002 and p = 0.001, respectively). Histological analyses showed a more severe glomerulonephritis in CFA-injected mice compared with the control mice. In addition, lymphoid hyperplasia in spleen and lungs, myocarditis, and vasculitis were observed in the former, but not in the latter group. In conclusion, the injection of CFA in NZB/NZWF1 mice accelerated autoimmune manifestations resembling ‘ASIA’ syndrome in humans.

Identification of gene networks and pathways associated with Guillain-Barré syndrome

BACKGROUND

The underlying change of gene network expression of Guillain-Barré syndrome (GBS) remains elusive. We sought to identify GBS-associated gene networks and signaling pathways by analyzing the transcriptional profile of leukocytes in the patients with GBS.

METHODS AND FINDINGS

Quantitative global gene expression microarray analysis of peripheral blood leukocytes was performed on 7 patients with GBS and 7 healthy controls. Gene expression profiles were compared between patients and controls after standardization. The set of genes that significantly correlated with GBS was further analyzed by Ingenuity Pathways Analyses. 256 genes and 18 gene networks were significantly associated with GBS (fold change ≥2, P<0.05). FOS, PTGS2, HMGB2 and MMP9 are the top four of 246 significantly up-regulated genes. The most significant disease and altered biological function genes associated with GBS were those involved in inflammatory response, infectious disease, and respiratory disease. Cell death, cellular development and cellular movement were the top significant molecular and cellular functions involved in GBS. Hematological system development and function, immune cell trafficking and organismal survival were the most significant GBS-associated function in physiological development and system category. Several hub genes, such as MMP9, PTGS2 and CREB1 were identified in the associated gene networks. Canonical pathway analysis showed that GnRH, corticotrophin-releasing hormone and ERK/MAPK signaling were the most significant pathways in the up-regulated gene set in GBS.

CONCLUSIONS

This study reveals the gene networks and canonical pathways associated with GBS. These data provide not only networks between the genes for understanding the pathogenic properties of GBS but also map significant pathways for the future development of novel therapeutic strategies.

Activation-induced deaminase-deficient MRL/lpr mice secrete high levels of protective antibodies against lupus nephritis

OBJECTIVE

We previously generated MRL/lpr mice deficient in activation-induced deaminase (AID) that lack isotype switching and immunoglobulin hypermutation. These mice have high levels of unmutated (germline) autoreactive IgM, yet they experienced an increase in survival and an improvement in lupus nephritis that exceeded that of MRL/lpr mice lacking IgG. The purpose of the present study was to test the hypothesis that high levels of germline autoreactive IgM in these mice confer protection against lupus nephritis.

METHODS

Autoreactive IgM antibodies of various specificities, including antibodies against double-stranded DNA (dsDNA), from AID-deficient MRL/lpr mice were given to asymptomatic MRL/lpr mice, and the levels of cytokines, proteinuria, immune complex deposition in the kidneys, and glomerulonephritis were examined. Novel AID-deficient MRL/lpr mice that lack any antibodies were generated for comparison to AID-deficient MRL/lpr mice that secrete only IgM.

RESULTS

Treatment with IgM anti-dsDNA resulted in a dramatic improvement in lupus nephritis. Other autoreactive IgM antibodies, such as antiphospholipid and anti-Sm, did not alter the pathologic changes. Secretion of proinflammatory cytokines by macrophages and the levels of inflammatory cells and apoptotic debris in the kidneys were lower in mice receiving IgM anti-dsDNA. Protective IgM derived from AID-deficient MRL/lpr mice displayed a distinct B cell repertoire, with a bias toward members of the V(H) 7183 family.

CONCLUSION

IgM anti-dsDNA protected MRL/lpr mice from lupus nephritis, likely by stopping the inflammatory cascade leading to kidney damage. A distinct repertoire of V(H) usage in IgM anti-dsDNA hybridomas from AID-deficient mice suggests that there is enrichment of a dedicated B cell population that secretes unmutated protective IgM in these mice.

Human FoxP3+ regulatory T cells in systemic autoimmune diseases

Since the characterization of CD4(+)CD25(+) regulatory T (Treg) cells in mice, significant progress has been made in the definitions of the phenotype and the function of human Treg cells in health and in pathological conditions. Recent advances in the field leading to a better molecular definition of Treg subsets in humans and the description of the dynamics of differentiation of Treg cells should bring new insights in the understanding of human chronic systemic autoimmune diseases. How Treg cells are compromised in these diseases is a challenging issue because the elucidation of the mechanisms leading to such anomaly might lead to promising novel therapeutic approaches.

Reproductive immunology: a focus on the role of female sex hormones and other gender-related factors

Reproductive immunology has attracted the attention of researchers interested in fertility and pregnancy as well as those interested in immunity and autoimmunity. Over the past couple of decades, a wealth of data on the immune-reproductive interactions has been generated. This issue of the Journal will examine several topics including the role of immune factors in the induction of anti-Ro antibody-mediated autoimmunity in neonates and the immunological effects of gender and sex hormones. The possible implications of the research reviewed here for the development of novel therapeutic approaches are also addressed.

Reproductive immunology: current status and future directions (part I)

Extensive research work over the past couple of decades has indicated a series of intricate relations between immune and reproductive systems. A range of reproductive immunology topics including the roles of adoptive and innate immunity in infertility and pregnancy, the immune system's role in induction of labor and preterm delivery, and immuno-modulatory effects of the female sex hormones will be discussed in this and the next issue of the Journal. The implications of this research on the development of novel therapeutic approaches are also addressed.

Mechanotransduction and epigenetic control in autoimmune diseases

Differentiation of epithelial cells is required to define tissue architecture and appropriate function of these cells is associated with a specific pattern of gene expression. DNA methylation, post-translational modification of histones and chromatin remodeling are nuclear mechanisms implicated in epigenetic control of gene expression. All factors relevant to tissue differentiation, including cell adhesion and shape, extracellular stimuli and transcriptional control, modulate gene expression and, thus, some of them are likely to impact on nuclear mechanisms of epigenetic control. The epithelial cells of salivary glands from Sjögren's syndrome patients display alterations in cell adhesion and shape. In this review, we summarize how these alterations are thought to lead to chromatin remodeling and, in doing so, bring about changes in transcriptional patterns. Additionally, we discuss how mechanotransduction in cells with impaired structural organization is implicated in modifying gene expression in these patients.

Levels of transforming growth factor-beta are low in systemic lupus erythematosus patients with active disease

OBJECTIVE

Cytokines are central regulators of the immune response but the workings of this complex network in systemic lupus erythematosus (SLE) are not fully understood. We investigated a range of inflammatory and immune-modulating cytokines to determine their value as biomarkers for disease subsets in SLE.

METHODS

This was a cross-sectional study in 102 patients with SLE (87% women, disease duration 10.6 yrs). Circulating concentrations of interleukin 1β (IL-1β), IL-4, IL-6, IL-10, IL-12, IL-17, monocyte chemotactic protein 1 (MCP-1), macrophage inflammatory protein 1 (MIP-1α), MIP-1β, interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and total transforming growth factor-β1 (TGF-β1) were related to disease activity (SLE Disease Activity Index; SLEDAI), lymphocyte subsets, autoantibody levels, accrued damage (Systemic Lupus International Collaborating Clinics/ACR Damage Index; SDI), and concomitant treatment.

RESULTS

Patients with SLE had lower levels of TGF-β1 (p = 0.01) and IL-1β (p = 0.0004) compared to controls. TGF-β1 levels were lower in patients with SLEDAI scores 1-10 and SDI > 3; and were correlated with CD4+, CD8+, and natural killer cell counts; and were independent of steroid or cytotoxic drug use. Treatment with cardiovascular drugs was associated with lower IL-12 levels. No consistent disease associations existed for the other cytokines investigated.

CONCLUSION

Lower TGF-β1 was the most consistent cytokine abnormality in patients with SLE. The associations with disease activity, lymphocyte subsets, and damage suggest that TGF-β1 may be a therapeutic target of interest in SLE.

Estradiol targets T cell signaling pathways in human systemic lupus

The major risk factor for developing systemic lupus erythematosus (SLE) is being female. The present study utilized gene profiles of activated T cells from females with SLE and healthy controls to identify signaling pathways uniquely regulated by estradiol that could contribute to SLE pathogenesis. Selected downstream pathway genes (+/- estradiol) were measured by real time polymerase chain amplification. Estradiol uniquely upregulated six pathways in SLE T cells that control T cell function including interferon-alpha signaling. Measurement of interferon-alpha pathway target gene expression revealed significant differences (p= 0.043) in DRIP150 (+/- estradiol) in SLE T cell samples while IFIT1 expression was bimodal and correlated moderately (r= 0.55) with disease activity. The results indicate that estradiol alters signaling pathways in activated SLE T cells that control T cell function. Differential expression of transcriptional coactivators could influence estrogen-dependent gene regulation in T cell signaling and contribute to SLE onset and disease pathogenesis.