Type 17 T-helper cells might be a promising therapeutic target for systemic lupus erythematosus. ACTA ACUST UNITED AC. 2008;4:352-353. [PMID: 18477998 DOI: 10.1038/ncprheum0815]

Advances in Systemic Lupus Erythematosus Treatment With Monoclonal Antibodies: A Mini-Review

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that affects multiple organs and systems. It is characterized by the production of abnormal antibodies that attack healthy cells and tissues. The disease presents a wide range of symptoms and severity, from mild to severe. Diagnosis can be complex, but the classification criteria of the American College of Rheumatology (ACR) help to facilitate it. Incidence and prevalence vary considerably worldwide, mainly affecting adult women between the third and fourth decades of life, although it can also occur in childhood. The prognosis of SLE has improved over time, but there is still a risk of irreversible organ damage. Treatment is individualized for each patient and is based on immunosuppression and the use of corticosteroids. Biological therapies, such as monoclonal antibodies, have emerged as a more specific alternative. Methotrexate, antimalarials, glucocorticoids, immunosuppressants, and monoclonal antibodies are some of the medications used to treat SLE. New therapeutic strategies are currently being developed, such as targeted therapies, immunomodulators, and biological agents. Treatment adherence, monitoring, and regular follow-up are important aspects of SLE management. This article aims to describe the characteristics of the new monoclonal antibody therapies that exist for the management of SLE.

Immunomodulatory effects of extracellular vesicles from mesenchymal stromal cells: Implication for therapeutic approach in autoimmune diseases

Autoimmune disease is characterized by the proliferation of harmful immune cells, inducing tissue inflammation and ultimately causing organ damage. Current treatments often lack specificity, necessitating high doses, prolonged usage, and high recurrence rates. Therefore, the identification of innovative and safe therapeutic strategies is urgently required. Recent preclinical studies and clinical trials on inflammatory and autoimmune diseases have evidenced the immunosuppressive properties of mesenchymal stromal cells (MSCs). Studies have demonstrated that extracellular vesicles (EV) derived from MSCs can mitigate abnormal autoinflammation while maintaining safety within the diseased microenvironment. This study conducted a systematic review to elucidate the crucial role of MSC-EVs in alleviating autoimmune diseases, particularly focusing on their impact on the underlying mechanisms of autoimmune conditions such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and inflammatory bowel disease (IBD). By specifically examining the regulatory functions of microRNAs (miRNAs) derived from MSC-EVs, the comprehensive study aimed to enhance the understanding related to disease mechanisms and identify potential diagnostic markers and therapeutic targets for these diseases.

Current Treatment Approach, Emerging Therapies and New Horizons in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE), the prototype of systemic autoimmune diseases is characterized by extreme heterogeneity with a variable clinical course. Renal involvement may be observed and affects the outcome. Hydroxychloroquine should be administered to every lupus patient irrespective of organ involvement. Conventional immunosuppressive therapy includes corticosteroids, methotrexate, cyclophosphamide, mycophenolate mofetil, azathioprine, cyclosporine and tacrolimus. However, despite conventional immunosuppressive treatment, flares occur and broad immunosuppression is accompanied by multiple side effects. Flare occurrence, target organ involvement, side effects of broad immunosuppression and increased knowledge of the pathogenetic mechanisms involved in SLE pathogenesis as well as the availability of biologic agents has led to the application of biologic agents in SLE management. Biologic agents targeting various pathogenetic paths have been applied. B cell targeting agents have been used successfully. Belimumab, a B cell targeting agent, has been approved for the treatment of SLE. Rituximab, an anti-CD20 targeting agent is also used in SLE. Anifrolumab, an interferon I receptor-targeting agent has beneficial effects on SLE. In conclusion, biologic treatment is applied in SLE and should be further evaluated with the aim of a good treatment response and a significant improvement in quality of life.

Significance of Interleukin 23 in Systemic Lupus Patients: Relation to Disease Activity and Damage Indices

Background

Dysregulation of both cellular and humoral immune responses is central in systemic lupus erythematosus (SLE) pathogenetic mechanisms. Proinflammatory cytokines, such as interleukin 23 (IL23), and their roles in promoting such dysregulation have recently been highly considered. This research compared IL23 serum levels in 85 Egyptian SLE patients and 85 healthy controls. Then, IL23 level was correlated to various SLE disease parameters, disease activity, and damage indices.

Results

IL23 serum levels were significantly elevated in SLE patients versus healthy individuals. Furthermore, IL23 levels were positively correlated with SLE disease activity index (SLEDAI) and were positively correlated with arthritis, seizures, consumption of complements (C3, C4), and with parameters of nephritis (hematuria, pyuria, casts, and proteinuria). A positive correlation was also found between IL23 levels and oral prednisolone dose.

Conclusion

IL23 has higher levels in the serum of SLE patients, and is correlated to activity of the disease, especially lupus nephritis. Further researchis needed to explore its exact role in SLE pathogenesis and whether it can be considered a potential biomarker or therapeutic target in SLE.

RNAi Silencing of HIF-1α Ameliorates Lupus Development in MRL/lpr Mice

Th17 cell and IL-17-mediated autoimmunity and inflammatory responses have been implicated in the development of organ damage in systemic lupus erythematosus (SLE), and new evidence suggests that hypoxia-inducible factor 1α (HIF-1α) enhances Th17 differentiation and promotes IL-17 production. However, the role of HIF-1α in the pathogenesis of lupus has not been examined. In this study, we silenced HIF-1α in vivo in a murine model of SLE to investigate whether lupus progression and the associated inflammatory pathways were affected by downregulating HIF-1α. Treatment with HIF1α-shRNA suppressed serum IL-17 level in MRL/lpr mice. Decreased anti-nucleosome antibody level, reduced urinary protein concentrations, ameliorated pathological damage, and remarkably reduced renal IgG and C3 depositions were observed in HIF1α-shRNA-treated group compared to those in the controls. Our results provide the first evidence for a role of HIF-1α in the pathogenesis of lupus and suggest a potential new therapeutic avenue for the treatment of lupus patients through reducing the HIF-1α level.

Hydroxychloroquine Inhibits the Differentiation of Th17 Cells in Systemic Lupus Erythematosus

Objective.

Hydroxychloroquine (HCQ) is a commonly used medicine for the treatment of systemic lupus erythematosus (SLE), and Th17 cells are closely related to the pathogenesis of SLE. However, the role and mechanism of HCQ on Th17 cell differentiation in SLE is not clearly understood. Here, we investigate the effect of HCQ on Th17 cell differentiation bothin vitroand in patients with SLE.

Methods.

Twenty-five patients with SLE were divided into 2 treatment groups: prednisone alone and HCQ plus prednisone. Interleukin 17 (IL-17) expression was analyzed by ELISA and real-time (RT)-PCR. Th17 were measured in patients with SLE by flow cytometry before and after HCQ treatment.In vitro, naive T cells were cultured in Th17-inducing conditions with or without HCQ. Cell differentiation and IL-17 expression were analyzed. Finally, transcriptome sequencing identified differential gene expression between naive T cells and induced Th17 cells.

Results.

In patients, HCQ plus prednisone treatment inhibited IL-17 production, gene expression, and Th17 cell differentiation.In vitro, HCQ inhibited Th17 cell proliferation and differentiation, as well as IL-17 production. Five microRNA were significantly different in Th17 cells compared with naive T cells, and HCQ treatment reversed this effect.In vivo, microRNA-590 (miR-590) was verified and was significantly decreased in Th17 cells, compared with naive T cells from lupus-prone mice. Moreover, miR-590 was increased in patients treated with HCQ plus prednisone.

Conclusion.

HCQ inhibited Th17 cell differentiation and IL-17 production bothin vitroand in patients with SLE. Our study provides additional evidence for HCQ as a treatment for SLE.

Th9 cells and IL-9 in autoimmune disorders: Pathogenesis and therapeutic potentials

Naïve CD4⁺ T cells are pleiotropically divided into various T helper (Th) cell subsets, according to their pivotal roles in the regulation of immune responses. The differentiation of Th9 cells, an interleukin (IL)-9 producing subset, can be impacted by specific environmental cues, co-stimulation with transforming growth factor β (TGF-β) and IL-4, and other regulatory factors. Although IL-9 has been recognized as a classical Th2-related cytokine, recent studies have indicated that IL-9-producing cells contribute to a group of autoimmune disorders including systemic lupus erythematosus (SLE), multiple sclerosis (MS), inflammatory bowel diseases (IBD), rheumatoid arthritis (RA) and psoriasis. Studies of Th9 cells in autoimmune diseases, although in their infancy, are expected to be of growing interest in the study of potential mechanisms of cytokine regulatory pathways and autoimmune pathogenesis. Several in vitro and in vivo pre-clinical trials have been conducted to explore potential therapeutic strategies by targeting the IL-9 pathway. Specifically, anti-IL-9 monoclonal antibodies (mAbs) and IL-9 inhibitors may potentially be used for the clinical treatment of allergic diseases, autoimmune diseases or cancers. Here, we review recent research on Th9 cells and IL-9 pertaining to cell differentiation, biological characteristics and pivotal cellular inter-relationships implicated in the development of various diseases.

miR-148a-3poverexpression contributes to glomerular cell proliferation by targeting PTEN in lupus nephritis

The objective of this study was to investigate the role of miR-148a-3p in lupus nephritis (LN) based on data from previous studies and a microRNA assay. We evaluated the miR-148a-3p expression level in LN renal tissues and blood serum to determine its clinicopathological significance and effect on glomerular cell proliferation. Then, we collected renal glomeruli from LN mice and determined the miR-148a-3p, proliferating cell nuclear antigen (PCNA), and PCNA/Thy1 expression. We performed functional analyses of miR-148a-3p in vitro and in vivo. We also investigated the target gene of miR-148a-3p in LN. The results showed that miR-148a-3p expression levels were significantly higher not only in glomeruli but also in the blood serum during LN and increased in the glomeruli of LN mice and that at the same time there was positive correlation between miR-148a-3p and PCNA expression of glomruli. Overexpression of miR-148a-3p accelerated cell proliferation and PCNA expression, while a miR-148a-3p inhibitor inhibited cell proliferation via the Akt/cyclin D1 pathway. Furthermore, miR-148a-3p overexpression reduced the phosphatase and tensin homology deleted on chromosome ten (PTEN) expression level, while miR-148a-3p silencing increased its expression in high-mobility group box 1 (HMGB1)-induced mouse mesangial cells (MMCs). Luciferase assays demonstrated that miR-148a-3p could directly bind to the PTEN 3′-UTR. PTEN overexpression inhibited MMC proliferation considerably, resembling the results observed during miR-148a-3p inhibition. Reducing miR-148a-3p expression upregulated PTEN in the glomeruli and improved renal function in LN mice. Thus miR-148a-3p may promote proliferation and contribute to LN progression by targeting PTEN.

The roles of Egr-2 in autoimmune diseases

Being a member of the early growth response (Egr) family of transcription factors, Egr-2 is expressed in a variety of cell types of the immune system. Recent findings imply that Egr-2 is important in the development and function of T helper (Th) 17 cell, regulatory T (Treg) cell, as well as dendritic cell (DC). Although these cells perform significantly in the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus, multiple sclerosis, and systemic sclerosis, the roles of Egr-2 in the pathogenesis of autoimmune diseases can not be neglected. In this article, we will discuss recent findings about the important roles of Egr-2 in immune cells and the possible pathological roles of Egr-2 in autoimmune diseases.

The role of serum IL-17 and IL-6 as biomarkers of disease activity and predictors of remission in patients with lupus nephritis

AIM

To determine the role of IL-17 and IL-6 in the pathogenesis of SLE as biomarkers of disease activity and predictors of remission and outcome of therapy in patients with active lupus nephritis.

METHODS

The study was carried out on 72 SLE female patients and 70 sex- and age-matched normal healthy subjects as controls. SLE disease activity was assessed in all patients with (SLEDAI-2k scores). Plasma levels of IL-6, and IL-17 were measured by enzyme linked immunosorbent assay and their levels were correlated with clinical manifestations of the disease and (SLEDAI-2k). ROC curve analysis was performed to determine the validity of both cytokines in prediction of activity and remission of active lupus nephritis.

RESULTS

SLE patients were found to have significantly higher levels of IL-17 (p<0.001) and IL-6 (p<0.001), in relation to normal subjects. Active group of patients had higher levels of both cytokines than the inactive one (P<0.001). Elevated serum levels of both cytokines were associated with active lupus nephritis, anemia and positively correlated with SLEDAI-2k scores (P=0.025 for IL-17 and P<0.001 for IL-6). There was a significant positive correlation between IL-6 and IL-17 serum concentrations during periods of disease activity (r=0.497, P=0.005) as well as during remission (r=0.662, P<0.001). ROC curve analysis for IL-6 and IL-17, as predictor of disease activity reviled, optimal cutoff level of 12.3 pg/ml and 19.7 pg/ml, with AUC=0.93, and 0.95, for both cytokines respectively, while as predictors of remission of active lupus nephritis, provide a cutoff value of IL-6 at 20.8 pg/ml, with AUC 0.80, and a cutoff value of IL-17 at 27.0 pg/ml, with AUC 0.82.

CONCLUSION

In conjunction with their major role in pathogenesis of SLE, baseline serum levels of IL-6 and IL-17 can be used as sensitive biomarkers for disease activity, as well as predictors of remission of lupus nephritis.

Decreased interleukin 35 and CD4+EBI3+ T cells in patients with active systemic lupus erythematosus

BACKGROUND

Interleukin 35 (IL-35) is likely to contribute to the development of autoimmune diseases, as the Epstein-Barr virus-induced gene protein 3 (EBI3) is the specificity subunit of IL-35. Nevertheless, until recently, no studies have evaluated its role in systemic lupus erythematosus (SLE) in humans. The objective of this study was to investigate the serum IL-35 level and the percentage of CD4EBI3 T cells in the peripheral blood of patients with SLE and explore the roles of double-positive T cells and IL-35 in the pathogenesis of SLE and the effects of glucocorticoid on these roles.

METHODS

Fifty-five hospitalized patients with SLE were recruited, and 20 volunteers were enrolled as healthy controls. Serum IL-35 levels were measured by enzyme-linked immunosorbent assay, and the percentage of CD4EBI3 T cells was analyzed by flow cytometry.

RESULTS

The serum IL-35 level and the percentage of CD4EBI3 T cells were significantly decreased in patients with active SLE compared with healthy controls and patients with inactive SLE. The serum IL-35 level and the percentage of CD4EBI3 T cells were negatively correlated with the SLE disease activity index. The percentages of CD4EBI3 T cells and serum IL-35 levels in 10 untreated patients with active SLE were increased at days l, 3, and 7 after the treatment with methylprednisolone (0.8 mg·kg·d) compared with the percentages before the treatment.

CONCLUSIONS

These results demonstrate that abnormalities in IL-35 and CD4EBI3 T cells may play important roles in the pathogenesis of SLE; the percentage of double-positive T cells and the level of IL-35 are parameters for the evaluation of SLE activity and severity.

Systemic lupus erythematosus patients in the low-latitude plateau of China: altitudinal influences

The current study was to investigate the features of hospitalized patients with systemic lupus erythematosus (SLE) at different altitudes. The correlation between SLE activity and altitudinal variations was also explored. Medical records of 1029 patients were retrospectively reviewed. Activity of SLE in each organ system was recorded using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). There was no significant correlation between SLE activity and altitudes (r = 0.003, p = 0.159). Age at onset for SLE patients at high altitudes was significantly younger than that at low and moderate altitudes (p = 0.022 and p = 0.004, respectively). Age at SLE admission at low altitudes was significant older than those at moderate and high altitudes (p = 0.011 and p < 0.001, respectively). Patients at high altitudes had shorter duration from disease onset to admission than those at moderate altitudes (p = 0.009). Incidence of Sm antibodies-positive for resident patients at high altitudes was 36.4%, which were higher than that at moderate altitudes (p = 0.003). We found increasing trends of CNS activity in active patients; immunological and renal activities in inactive patients were correlated with elevated altitudes (p = 0.024, p = 0.004, p = 0.005), while arthritis scores in active patients showed the tendency of decreasing with the rise of elevation (p = 0.002). Hemoglobin level, red blood cell and platelet counts at high altitudes were significantly lower than those at low altitudes (p < 0.05, respectively). There was no significant difference in hemoglobin level between moderate- and low-altitude groups (p > 0.05). No significant difference in platelet counts between moderate- and high-altitude groups was observed (p > 0.05). Our findings suggest that some clinical features, laboratory tests and activity of main organs in SLE are influenced by altitudes. Furthermore, organ activities of active and inactive SLE patients have different patterns of altitudinal variations. These distinctive variations likely reveal that peculiar environmental factors at high altitudes can affect the development of SLE.

APRIL levels strongly correlate with IL-17 in systemic lupus erythematosus

Introduction

Activated self-reactive B cells play an important part in systemic lupus erythematosus (SLE). A proliferation-inducing ligand (APRIL) and B cell-activating factor (BAFF) are B-cell specific stimulators, but activate B cells through different receptors. We investigated the reciprocal association between serum APRIL (s-APRIL), serum BAFF (s-BAFF) and immunological and clinical findings in SLE patients.

Methods

A cross-sectional case-control study was performed in 100 SLE patients (87% female, age 49 years, disease duration 12 years). APRIL and BAFF levels were measured by sandwich ELISA, compared with healthy controls and correlated with autoantibody, cytokine (IL-6 and IL-17) and clinical findings through nonparametric and multivariate regression analyses.

Results

Both median s-APRIL (478 vs. 0 pg/ml, p = 0.01) and s-BAFF (1720 vs. 0.9 pg/ml, p < 0.001) were higher in SLE patients than controls. Increased s-BAFF was observed in 86% of patients, while s-APRIL was increased only in 17% ( p < 0.01). S-APRIL correlated with s-BAFF in controls ( p = 0.04), but not in SLE ( p = 0.8). Increased s-APRIL was strongly and independently associated with IL-17 activation ( p < 0.001), while increased s-BAFF levels were associated with anti-nucleosome antibody presence ( p = 0.001). Disease activity and organ damage were associated with s-BAFF but not s-APRIL.

Conclusions

While both s-BAFF and s-APRIL levels are elevated in SLE patients, they reflect different immunologic and clinical pathways. The strong association between s-APRIL and IL-17 activation supports a role for Th17 helper cells in B cell activation in SLE.

Hypomethylation of interleukin 6 correlates with renal involvement in systemic lupus erythematosus

OBJECTIVE

To analyze peripheral blood interleukin 6 (IL-6) methylation status and its clinical significance in patients with systemic lupus erythematosus (SLE).

MATERIAL AND METHODS

Blood samples from 41 adult patients with SLE, and 20 healthy controls were collected. The methylation status of IL-6 was determined by methylation specific polymerase chain reaction (MSP). The IL-6 expression was detected by real-time PCR. Correlations between IL-6 methylation status and clinical features or laboratory findings in patients with SLE were investigated.

RESULTS

The methylation status and expression of IL-6 in peripheral blood could reflect the level in peripheral blood mononucleated cells (PBMCs) of SLE. Significantly positive correlation was found between IL-6 hypomethylation and renal disorder. Interleukin 6 hypomethylation was found negatively correlated with serum C3.

CONCLUSIONS

The detection of IL-6 methylation status in peripheral blood could reflect the status in PBMC with SLE. Interleukin 6 may play a role in renal disorder with SLE patients. Interleukin 6 could be considered as a new biomarker for predicting SLE flare.

Role of Th22 cells in inflammatory, autoimmune diseases and tumors

T-helper (Th) 22 cells are a recently identified subset of T cells, which are characterized by abundant secretion of interleukin-22 (IL-22) but not interleukin-17 (IL-17) or interferon-γ (IFN-γ) and are therefore distinct from Th1, Th2 and Th17 cells. The functions of Th22 cells are predominantly executed by their signature cytokine IL-22, which has been shown to play an important role in the pathogenesis of inflammatory, autoimmune diseases and tumors. Th22 cells and related cytokine IL-22 regulate multiple biological functions and have an important role in a number of diseases. The effect of Th22 cells and IL-22 on different cells seems to be quite similar, including improving the innate immunity, protecting from injury, and enhancing their regeneration, but whether its role is protective or pathogenic is dependent on the nature of the affected tissue and local cytokine milieu. Nevertheless, there are still many questions about the role of Th22 and related cytokine IL-22 in various diseases. This article reviews the role of Th22 cells and its cytokine IL-22 in inflammatory, autoimmune diseases and tumors.

Expression of human T cell immunoglobulin domain and mucin-3 (TIM-3) on kidney tissue from systemic lupus erythematosus (SLE) patients

The aim of this study was to evaluate the expression of TIM-3 in renal tissue from patients with systemic lupus erythematosus (SLE) and patients without SLE, and to evaluate the difference of TIM-3 expression between them. A total of 272 patients with SLE as SLE group and 62 patients without SLE as control group were enrolled in the present study. Patients with SLE accepted percutaneous renal biopsy. We examined the expression of TIM-3 in renal tissue and the serological parameters in serum from all enrolled cases. The expression of TIM-3 and serological parameters were compared between the different groups. Positive staining of TIM-3 protein was seen in 97.1 % patients with SLE (264 out of 272), but 95.2 % negative staining in the cases without SLE (59 out of 62), only 3 out of 62 patients in control group were positive staining of TIM-3. There were significant differences between two groups in almost all serological markers which reflect SLE activity. There was a nearly positive correlation between pathological manifestations and expression degree of TIM-3. High immuno-reactivity of TIM-3 was found to be significantly correlated with serological grade (p < 0.001), but there was the phenomenon in control group. The results showed that there was the expression of TIM-3 in renal tissue from the patients with SLE, but rarely expression in cases without SLE. Expression of TIM-3 was associated with the diseases' activity.

Perspectives of the relationship between IL-7 and autoimmune diseases

Interleukin (IL)-7 is one of the IL-2 family cytokines comprised of IL-2, IL-4, IL-7, IL-9, IL-15, as well as IL-21. IL-7 is mainly secreted by stroma cells in primary lymphoid tissues, playing an essential role in the program of T cell development. Recently, studies have revealed that physiological function exerted by immunocytes can be influenced by aberrant IL-7 signaling, which is common in abnormal autoimmunity regulation. There is also increasing evidence that IL-7 is involved in several autoimmune diseases, such as rheumatoid arthritis, type I diabetes, multiple sclerosis and systemic lupus erythematosus, etc. Targeting components in IL-7 signaling pathways may have potential significance for treating numerous autoimmune diseases. In this review, we therefore summarize our current understandings regarding the relationship between IL-7 and autoimmune diseases so as to render more valuable information on this kind of research.

Dominant Th1 and minimal Th17 skewing in discoid lupus revealed by transcriptomic comparison with psoriasis

Discoid lupus erythematosus (DLE) is the most common skin manifestation of lupus. Despite its high frequency in systemic lupus in addition to cases without extracutaneous manifestations, targeted treatments for DLE are lacking, likely because of a dearth of knowledge of the molecular landscape of DLE skin. Here, we profiled the transcriptome of DLE skin in order to identify signaling pathways and cellular signatures that may be targeted for treatment purposes. Further comparison of the DLE transcriptome with that of psoriasis, a useful reference given our extensive knowledge of molecular pathways in this disease, provided a framework to identify potential therapeutic targets. Although a growing body of data support a role for IL-17 and T helper type 17 (Th17) cells in systemic lupus, we show a relative enrichment of IFN-γ-associated genes without that for IL-17-associated genes in DLE. Extraction of T cells from the skin of DLE patients identified a predominance of IFN-γ-producing Th1 cells and an absence of IL-17-producing Th17 cells, complementing the results from whole-skin transcriptomic analyses. These data therefore support investigations into treatments for DLE that target Th1 cells or the IFN-γ signaling pathway.

Decreased serum level of IL-21 in new-onset systemic lupus erythematosus patients

This study aims to investigate the serum IL-21 levels in systemic lupus erythematosus (SLE) and its relations with clinical and laboratory features. Fifty-seven patients with SLE and 30 healthy volunteers were recruited in the current study. Serum IL-21 levels were detected by enzyme-linked immunosorbent assay. Statistical analyses were performed by SPSS 10.01. Results showed that IL-21 levels were significantly decreased in the serum of patients with SLE compared with controls (P = 0.026). There was no significant difference regarding serum IL-21 level between SLE patients with nephritis and those without nephritis (P = 0.066); no significant difference was found between less active SLE and more active SLE (P = 0.588). The presence of anemia was associated with low serum IL-21 levels (P = 0.030) in SLE patients. In summary, decreased serum level of IL-21 and its association with anemia indicate a possible role of IL-21 in human SLE. However, further studies are needed to confirm this preliminary results.

Th22 and related cytokines in inflammatory and autoimmune diseases

INTRODUCTION

Th22 and related cytokines regulate various processes and have been linked to diverse effects. The levels of Th22 and cytokine IL-22 are increased in several disorders and positively related to some autoimmune diseases. Preclinical studies have suggested that the inhibition or stimulation of IL-22 is an attractive approach to reverse the immune disorders. Simultaneously, considering many patients with refractory autoimmune diseases respond poorly to the therapies which are highly toxic, more effective therapies are to be examined.

AREAS COVERED

The role of Th22 cells and related cytokines and therapeutic strategies targeting them in many illnesses, especially inflammatory and autoimmune diseases.

EXPERT OPINION

Th22 cells and related cytokine IL-22 regulate multiple biological functions and play an important role in a number of inflammatory and autoimmune diseases. They have unique and attractive advantages for targeting. Targeting IL-22 has already been trialed in many mice experiments, showing better efficacy and fewer side effects compared with classical drugs. Targeting IL-22 or Th22 might provide pathogenetic treatment. However, Th22 subset is a recently identified Th subset and its associated research is extremely limited. Therefore, there are still many unanswered questions and further researches are warranted.

Emerging role of interleukin-22 in autoimmune diseases

Interleukin-22 (IL-22) is an IL-10 family cytokine member that was recently discovered to be mainly produced by Th17 cells. Previous studies have indicated the importance of IL-22 in host defense against Gram-negative bacterial organisms (in gut and lung). Recently, there is emerging evidence that IL-22 is involved in the development and pathogenesis of several autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), multiple sclerosis (MS), Sjögren's syndrome (SS) and psoriasis. Therapeutics targeting IL-22 therefore may have promise for treating various autoimmune diseases. In this review, we discuss the recent progression of the involvement of IL-22 in the development and pathogenesis of autoimmune diseases, as well as its clinical implications and therapeutic potential.

Increased interleukin‑9 and CD4+IL-9+ T cells in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease of unknown origin affecting all the organ systems. Apart from genetic and environmental factors, autoantibody and immune complex deposition as well as cytokine imbalances contribute to immune dysfunction. Interleukin‑9 (IL-9) is a T cell-derived factor preferentially expressed by CD4+ T cells and it has been characterized in human and murine systems. IL-9 targets cells of the lymphoid, myeloid and mast cell lineages, and is likely to contribute to the development of allergic and autoimmune diseases such as asthma, arthritis, multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). Nevertheless, until recently there have been no studies on its role in SLE in humans. In the present study, the mRNA and serum IL-9 levels in the peripheral blood of SLE patients and healthy controls were assessed using real-time PCR and enzyme-linked immunosorbent assay (ELISA), respectively. Flow cytometry was used to analyze the percentages of CD4+IL-9+ T cells in SLE patients. Moreover, differences between the groups and the effect of glucocorticoids were analyzed. The results showed that the plasma concentration and mRNA levels of IL-9 were significantly elevated in SLE patients compared with the healthy controls. The percentages of CD4+IL-9+ T cells were also increased in SLE patients. In addition, serum IL-9 levels and the percentages of CD4+IL-9+ T cells were correlated with the SLE disease activity index (SLEDAI). Additionally, the percentages of CD4+IL-9+ T cells and serum IL-9 levels in 8 untreated active SLE patients were decreased at 1, 2 and 3 weeks after treatment with methylprednisolone. In conclusion, we provide evidence that IL-9 is increased in SLE patients. Moreover, it is described for the first time that high expression of IL-9 levels and the percentages of CD4+IL-9+ T cells correlate with disease activity and severity. This suggests an important role of IL-9 in the pathogenesis of SLE.

MicroRNA-101, mitogen-activated protein kinases and mitogen-activated protein kinases phosphatase-1 in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is the prototype of human autoimmune disease in which various inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1, IL-6 and interferon (IFN) play crucial pathogenic roles. The production of these cytokines is responsible for the mitogen-activated protein kinases (MAPKs), which can also generate mitogen-activated protein kinases phosphatases (MKPs). MKP-1, a prototypical member of the MKP family that can influence outcomes of autoimmune diseases and reduce the inflammatory cytokines by dephosphorylation of p38 and JNK MAPK, plays a critical role in the expression of inflammatory mediators at transcriptional and post-transcriptional levels. MicroRNA-101 (miR) is a small non-coding RNA that regulates the MAPK response by targeting MKP-1 mRNA 3′-UTR, and affects the secretion of the downstream inflammatory cytokines. However, the interaction among the above three in the pathogenesis of SLE has not previously been reported. This review discusses the current understanding of the role of the MAPK/MKP/miR-101 axis in regulating immune responses and the pathogenesis of SLE to provide new ideas for clinical treatment of SLE.

Expression profiles of Th17 pathway related genes in human systemic lupus erythematosus

Recently, evidence is emerging that inappropriate regulation of type 17 T helper cells (Th17) plays a fundamental role in the development of many autoimmune diseases including systemic lupus erythematosus (SLE). However, the role of Th17-related cytokines in SLE remains elusive. To further investigate the role and imbalance of Th17-related cytokines in the pathogenesis of SLE. A Quantitative RT-PCR Array (Human Th17 for Autoimmunity & Inflammation PCR Array) analyses were performed to study Th17-related genes expression in peripheral white blood cells of 25 new-onset patients with SLE and 15 healthy subjects. When gene expression for SLE patients was compared to the mean of normal controls, among the 84 target genes related to Th17 pathway, 7 (CXCL1, ICAM1, IL10, IL5, IL8, ISG20, JAK2,) were upregulated and 6 (CD28, CD40LG, S1PR1, IL17RE, IL23R, RORC) downregulated. However, comparisons of mRNA expression of Th17 related cytokines between lupus nephritis (LN) patients and SLE patients without nephritis (SLE non LN) showed no significant difference. In conclusion, SLE patients and normal controls showed different expression of a few genes in Th17 pathway, indicating that the pathway may be involved in the pathogenesis of SLE.

IL-21 receptor is required for the systemic accumulation of activated B and T lymphocytes in MRL/MpJ-Fas(lpr/lpr)/J mice

MRL/MpJ-Fas(lpr/lpr)/J (MRL(lpr)) mice develop lupus-like disease manifestations in an IL-21-dependent manner. IL-21 is a pleiotropic cytokine that can influence the activation, differentiation, and expansion of B and T cell effector subsets. Notably, autoreactive CD4(+) T and B cells spontaneously accumulate in MRL(lpr) mice and mediate disease pathogenesis. We sought to identify the particular lymphocyte effector subsets regulated by IL-21 in the context of systemic autoimmunity and, thus, generated MRL(lpr) mice deficient in IL-21R (MRL(lpr).IL-21R(-/-)). Lymphadenopathy and splenomegaly, which are characteristic traits of the MRL(lpr) model were significantly reduced in the absence of IL-21R, suggesting that immune activation was likewise decreased. Indeed, spontaneous germinal center formation and plasma cell accumulation were absent in IL-21R-deficient MRL(lpr) mice. Correspondingly, we observed a significant reduction in autoantibody titers. Activated CD4(+) CD44(+) CD62L(lo) T cells also failed to accumulate, and CD4(+) Th cell differentiation was impaired, as evidenced by a significant reduction in CD4(+) T cells that produced the pronephritogenic cytokine IFN-γ. T extrafollicular helper cells are a recently described subset of activated CD4(+) T cells that function as the primary inducers of autoantibody production in MRL(lpr) mice. Importantly, we demonstrated that T extrafollicular helper cells are dependent on IL-21R for their generation. Together, our data highlighted the novel observation that IL-21 is a critical regulator of multiple pathogenic B and T cell effector subsets in MRL(lpr) mice.

Th22 in inflammatory and autoimmune disease: prospects for therapeutic intervention

T helper cell 22 (Th22) is a new subset of T cells clearly separate from Th17 and other known T cell subsets with distinct gene expression and function. With the CCR6 + CCR4 + CCR10 + phenotype and aryl hydrocarbon receptor as the key transcription factor, Th22 subsets produce cytokines such as IL-22, whose function depends on the activation of signal transduction and activators of transcription 3. IL-22 was up-regulated in Rheumatoid arthritis, Crohn's disease, Psoriasis, and atopic dermatitis patients whereas it was down-regulated in the serum of patients with sarcoidosis and systemic lupus erythematosus. Furthermore, it has been demonstrated that IL-22 may have promise as a potential therapeutic for chronic inflammatory diseases, and treatment with recombinant cytokine or gene therapy delivery of IL-22 may alleviate tissue destruction during inflammatory responses. In summary, Th22 cell plays an important and complicated role in inflammatory and autoimmune disease.

Type 17 T-helper cells might be a promising therapeutic target for osteoporosis

Osteoporosis, a disease characterized by low bone mass and deterioration of bone tissue, is a pressing public health problem. Recent studies have suggested a possible role of T-helper (Th) cells in the pathogenesis of bone loss which occurs in systemic inflammatory diseases. However, there are contradictions in the published literature regarding the functional role of Th1/Th2 cells in the regulation of the differentiation of osteoclasts. These paradoxes have now been clarified by the recent discovery of Th17 cells, a novel subset of Th cells that selectively secrete several proinflammatory cytokines, mainly IL-17. It has been confirmed that Th17 cells have stimulatory effects on osteoclastogenesis and accelerate bone loss in animal models with inflammatory disorders. Targeting Th17 cells or IL-17 may inhibit the bone resorption with RA. Thus, we are led to suppose that Th17 cells might be promising therapeutic targets in osteoporosis.

Recovery of the immune balance between Th17 and regulatory T cells as a treatment for systemic lupus erythematosus

The Th17 lineage, a lineage of effector CD4(+) T cells, is characterized by the production of IL-17. Expansion of Th17 cells has been implicated in a growing list of autoimmune disorders. Our studies, as well as others, have shown that Th17 cells play a key role in the pathogenesis of SLE. Therefore, some investigators advocate that Th17 cells are a promising therapeutic target for SLE. However, neutralization of IL-17 in vivo actually aggravated inflammation by inducing infiltration of other effector cells. Thus, the therapeutic effects of antagonizing Th17 cells for the treatment of SLE in the clinic are worth discussing. Moreover, in patients with SLE, the expansion of effector T cells is always closely related to the depletion and dysfunction of Treg cells. Therefore, we hypothesize that for the treatment of SLE, we should focus on therapeutic agents that can regulate the immune balance between Th17 and Treg cells rather than on those that exclusively regulate Th17 cells.

Galectin-1-induced down-regulation of T lymphocyte activation protects (NZB x NZW) F1 mice from lupus-like disease

Systemic lupus erythematosus (SLE) is a complex autoimmune disease characterized by a hyperactive immune system, including activation of autoreactive T and B cells. These studies demonstrate that administration of recombinant galectin-1, a β-galactose binding protein, to SLE-prone (NZB × NZW) F1 mice reduced lymphocyte activation, inhibited serum anti-double-stranded DNA(dsDNA) IgG antibody production, decreased the incidence of proteinuria, and increased survival rate. In addition, recombinant galectin-1'-treated mice had a higher frequency of Foxp3 expression, which suggested an increase in the percentage of peripheral regulatory T cells. Consistent with the finding that there were fewer activated T lymphocytes, ex vivo T cells from mice treated with recombinant galectin-1 exhibited less proliferation in response to TCR stimulation. Furthermore, these cells were less efficient at lipid raft clustering in response to TCR/CD28 engagement, consistent with published reports that galectin-1 can reorganize the synaptic contact to interfere with TCR signaling and activation to prevent T cell activation. Aged galectin-1-deficient mice had higher serum levels of antibodies against dsDNA, elucidating a role for endogenous galectin-1 in decreasing susceptibility to autoimmunity. Together, the findings highlight galectin-1 as a novel potential therapeutic immune modulator for treatment of lupus-like disease.

Identification of Baicalin as an immunoregulatory compound by controlling T(H)17 cell differentiation

T_H17 cells have been implicated in a growing list of inflammatory disorders. Antagonism of T_H17 cells can be used for the treatment of inflammatory injury. Currently, very little is known about the natural compound controlling the differentiation of T_H17 cells. Here, we showed that Baicalin, a compound isolated from a Chinese herb, inhibited T_H17 cell differentiation both in vitro and in vivo. Baicalin might inhibit newly generated T_H17 cells via reducing RORγt expression, and together with up-regulating Foxp3 expression to suppress RORγt-mediated IL-17 expression in established T_H17 cells. In vivo treatment with Baicalin could inhibit T_H17 cell differentiation, restrain T_H17 cells infiltration into kidney, and protect MRL/lpr mice against nephritis. Our findings not only demonstrate that Baicalin could control T_H17 cell differentiation but also suggest that Baicalin might be a promising therapeutic agent for the treatment of T_H17 cells-mediated inflammatory diseases.

Elevated Th17 cells are accompanied by FoxP3+ Treg cells decrease in patients with lupus nephritis

To investigate the variations of T-helper 17 (Th17) and regulatory T (Treg) cells in patients with lupus nephritis (LN), a total of 60 systemic lupus erythematosus patients and 28 healthy controls (HCs) were enrolled. The frequency of Th17 cells and Treg cells in peripheral blood mononuclear cells (PBMCs) was evaluated by flow cytometric analysis. The serum concentrations of interleukin-17 (IL-17) and transforming growth factor-beta 1 (TGF-β1) were measured by enzyme-linked immunosorbent assay (ELISA). The results demonstrated in LN patients a significant decrease in the frequency of CD4+CD25(high) and CD4+CD25+FoxP3+ T cells and a significant increase in the frequency of Th17 cells in peripheral blood, and the ratio of Th17 to Treg cell frequency was significantly increased along with increased SLEDAI scores. LN patients had a lower percentage and expression of FoxP3 in CD4+CD25(high) T cells than SLE patients without nephritis. The concentration of TGF-β1 was found decreased in SLE patients compared with that from healthy controls, though no significant difference was found between LN patients and SLE patients without nephritis. The expression of IL-17 levels in LN patients exhibited a significant increase compared with patients without nephritis and healthy controls. Based on our results, the significantly elevated Th17 cells are accompanied by FoxP3+ Treg cells decrease in lupus nephritis, suggesting that Th17/Treg functional imbalance may be involved in the pathogenesis of renal damage in SLE patients.

Role and therapeutic potential of Glycodelin A in systemic lupus erythematosus

Glycodelin A (GdA) is a lipocalin with an immunomodulatory role. Low expression of GdA has been implicated in the progression of autoimmune disease. Therefore, strategies targeting GdA may constitute an important target for the design of drugs for autoimmune disease including systemic lupus erythematosus (SLE). This opinion article will focus on current understanding of the role of GdA in the physiological and pathological functions associated with SLE. It is the intention of the article to provide insights that may assist in the development of GdA-based approaches for the treatment of SLE.

Therapeutic potential of IL-27 in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by a diverse array of autoantibody production, complement activation and immune complex deposition, causing tissue and organ damage. Effective medical treatment for SLE is lacking because the etiology and pathogenesis of SLE are incompletely understood. It has been confirmed that cytokine-mediated immunity plays a crucial role in the pathogenesis of various autoimmune diseases including SLE. Recently, IL-27 was identified, which belongs to the IL-12 cytokine family. IL-27 exerts profound anti-inflammatory effects in several experimental autoimmune models. In particular, suppressive effects on T(H)17 cells, which are implicated in the pathogenesis of SLE. Moreover, administration of IL-27 or augmentation of IL-27 signaling suppresses some autoimmune diseases, including autoimmune diabetes and murine lupus, suggesting that IL-27 may be therapeutically relevant in SLE. In this article, we discuss the biological features of IL-27 and summarize recent advances on the role of IL-27 in the pathogenesis and treatment of SLE. Even though IL-27 has shown therapeutic potential in SLE, further research, particularly in humans, is needed in order to establish the precise role of IL-27 in SLE.

Tuberculosis in systemic lupus erythematosus in Chinese patients

This study investigates the prevalence and clinical and laboratory features of patients with systemic lupus erythematosus (SLE) associated with TB in Chinese patients, as well as its similarities to and differences from patients without TB. Our results show that SLE patients with TB (SLE-TB) might be a subgroup of patients with distinct clinical and laboratory features. Therefore, specific treatment should be given in order to provide a better outcome for SLE-TB patients.