Identification of regulatory T cells in systemic lupus erythematosus

Therapy with regulatory T-cell infusion in autoimmune diseases and organ transplantation: A review of the strengths and limitations

In the last decade, cell therapies have revolutionized the treatment of some diseases, earning the definition of being the "third pillar" of therapeutics. In particular, the infusion of regulatory T cells (Tregs) is explored for the prevention and control of autoimmune reactions and acute/chronic allograft rejection. Such an approach represents a promising new treatment for autoimmune diseases to recover an immunotolerance against autoantigens, and to prevent an immune response to alloantigens. The efficacy of the in vitro expanded polyclonal and antigen-specific Treg infusion in the treatment of a large number of autoimmune diseases has been extensively demonstrated in mouse models. Similarly, experimental work documented the efficacy of Treg infusions to prevent acute and chronic allograft rejections. The Treg therapy has shown encouraging results in the control of type 1 diabetes (T1D) as well as Crohn's disease, systemic lupus erythematosus, autoimmune hepatitis and delaying graft rejection in clinical trials. However, the best method for Treg expansion and the advantages and pitfalls with the different types of Tregs are not fully understood in terms of how these therapeutic treatments can be applied in the clinical setting. This review provides an up-to-date overview of Treg infusion-based treatments in autoimmune diseases and allograft transplantation, the current technical challenges, and the highlights and disadvantages of this therapeutic approaches."

CAR Treg: A new approach in the treatment of autoimmune diseases

Regulatory T cells (Tregs) have the role of regulating self-tolerance, and suppressing immune responses. Defects in Treg function and number can lead to in loss of tolerance or autoimmune disease. To treat or control autoimmune diseases, one of the options is to develop immune tolerance for Tregs cell therapy, which includes promotion and activation. Recently, cell-based treatment as a promising approach to increase cells function and number has been developed. Cell therapy by chimeric T antigen receptor (CAR-T) cells has shown significant efficacy in the treatment of leukemia, which has led researchers to use CAR-T cells in other diseases like autoimmune diseases. Here, we describe the existing treatments for autoimmune diseases and the available treatments based on Treg, their benefits and restrictions for implementation in clinical trials. We also discussed potential solutions to overcome these limitations. It seems novel designs of CARs to be new hope for autoimmune diseases and expected to be a potential cure option in a wide array of disease in the future. Therefore, it is very important to address this issue and increase information about it.

Rapid expansion of Treg cells protects from collateral colitis following a viral trigger

Foxp3⁺ regulatory T (Treg) cells are essential for maintaining peripheral tolerance and preventing autoimmunity. While genetic factors may predispose for autoimmunity, additional environmental triggers, such as viral infections, are usually required to initiate the onset of disease. Here, we show that viral infection with LCMV results in type I IFN-dependent Treg cell loss that is rapidly compensated by the conversion and expansion of Vβ5⁺ conventional T cells into iTreg cells. Using Vβ5-deficient mice, we show that these Vβ5⁺ iTreg cells are dispensable for limiting anti-viral immunity. Rather, the delayed replenishment of Treg cells in Vβ5-deficient mice compromises suppression of microbiota-dependent activation of CD8⁺ T cells, resulting in colitis. Importantly, recovery from clinical symptoms in IBD patients is marked by expansion of the corresponding Vβ2⁺ Treg population in humans. Collectively, we provide a link between a viral trigger and an impaired Treg cell compartment resulting in the initiation of immune pathology.

Leptin: an unappreciated key player in SLE

Leptin is the forerunner of the adipokine superfamily and plays a key role in regulating energy expenditure and neuroendocrine function. Researches into leptin put emphasize not only on the metabolic role but also its immunoregulatory effect on immune response through immunocyte activation and cytokine secretion. Leptin acts on receptors that are widespread throughout the body and that are expressed across many tissue types. As a consequence, the abnormal expression of leptin has been found to correlate with a number of diseases, including cancers, autoimmune diseases, and cardiovascular diseases. The significance of leptin in the development of autoimmune diseases is becoming increasingly prominent. Systemic lupus erythematosus (SLE) is a severe atypical autoimmune disease that causes damage to multiple organ systems. It is characterised by the following: impaired clearance of apoptotic cells, loss of tolerance to self-antigens, aberrant activation of T cells and B cells, and chronic inflammation. The heightened immunocyte response in SLE means that these physiological systems are particularly vulnerable to regulation by leptin in addition to being of great significance to the research field. Our current review provides insight into the regulatory roles that leptin plays on immune effector cells in SLE.

CD8+CD103+ iTregs Inhibit Chronic Graft-versus-Host Disease with Lupus Nephritis by the Increased Expression of CD39

Many patients with systemic lupus erythematosus (SLE) have lupus nephritis, one of the severe complications of SLE. We previously reported that CD8+CD103+ T regulatory cells induced ex vivo with transforming growth factor β (TGF-β) (iTregs) inhibited immune cells responses to ameliorate excessive autoimmune inflammation. However, the molecular mechanism(s) underlying the role of these CD8+ iTregs is still unclear. Here we identified that CD39, which is highly expressed on CD8+ iTregs, crucially contributes to the immunosuppressive role of the CD8+CD103+ iTregs. We showed that adoptive transfer of CD8+CD103+ iTregs significantly relieves the chronic graft-versus-host disease with lupus nephritis and CD39 inhibitor mostly abolished the functional activities of these CD8+ iTregs in vitro and in vivo. CD39+ cells sorted from CD8+CD103+ iTregs were more effective in treating lupus nephritis than CD39− partner cells in vivo. Furthermore, human CD8+ iTregs displayed increased CD103 and CD39 expressions, and CD39 was involved in the suppressive function of human CD8+ iTregs. Thus, our data implicated a crucial role of CD39 in CD8+CD103+ iTregs in treating lupus nephritis, and CD39 could be a new phenotypic biomarker for the identification of highly qualified CD8+ Tregs. This subpopulation may have therapeutic potential in patients with SLE nephritis and other autoimmune diseases.

Context-Dependent Effect of Glucocorticoids on the Proliferation, Differentiation, and Apoptosis of Regulatory T Cells: A Review of the Empirical Evidence and Clinical Applications

Glucocorticoids (GCs) are widely used to treat several diseases because of their powerful anti-inflammatory and immunomodulatory effects on immune cells and non-lymphoid tissues. The effects of GCs on T cells are the most relevant in this regard. In this review, we analyze how GCs modulate the survival, maturation, and differentiation of regulatory T (Treg) cell subsets into both murine models and humans. In this way, GCs change the Treg cell number with an impact on the mid-term and long-term efficacy of GC treatment. In vitro studies suggest that the GC-dependent expansion of Treg cells is relevant when they are activated. In agreement with this observation, the GC treatment of patients with established autoimmune, allergic, or (auto)inflammatory diseases causes an expansion of Treg cells. An exception to this appears to be the local GC treatment of psoriatic lesions. Moreover, the effects on Treg number in patients with multiple sclerosis are uncertain. The effects of GCs on Treg cell number in healthy/diseased subjects treated with or exposed to allergens/antigens appear to be context-dependent. Considering the relevance of this effect in the maturation of the immune system (tolerogenic response to antigens), the success of vaccination (including desensitization), and the tolerance to xenografts, the findings must be considered when planning GC treatment.

Peripheral and Intestinal T-regulatory Cells are Upregulated in Children with Inflammatory Bowel Disease at Onset of Disease

BACKGROUND/AIMS

To determine the proportion of T-regulatory cells (CD4⁺CD25^highFOXP3⁺ cells) in peripheral blood and the number of FOXP3⁺ cells in intestinal mucosa of children with inflammatory bowel disease (IBD), and to verify whether these parameters correlate with the activity of the disease.

MATERIAL AND METHODS

24 patients newly diagnosed for IBD were included in the study: ulcerative colitis (UC; n = 13) and Crohn's disease (CD; n = 11). Seventeen healthy controls (HC) and 16 patients with irritable bowel syndrome (IBS) served as a control group for peripheral and intestinal Tregs assessment, respectively. The disease activity was assessed by Pediatric Ulcerative Colitis Activity Index (PUCAI) and Pediatric Crohn's Disease Activity Index (PCDAI). Quantification of regulatory T cells of CD4⁺CD25^highFOXP3⁺ phenotype in peripheral blood was based on three-color flow cytometry. Mucosal Tregs represented by FOXP3⁺ cells were evaluated using immunohistochemistry.

RESULTS

Median proportion of CD4⁺CD25^highFOXP3⁺ cells among CD4⁺ T cells in peripheral blood (5.1%, range 1.7-84% vs. 4.3%, range 2-8.1%, p = 0.023) and median number of intestinal FOXP3+ cells (115.33 per high-power field, hpf, range 39.33-375.67 vs. 10.16 per hpf, range 5-30, p = 0.0001) were significantly higher in children with IBD than in the controls. The proportion of circulating Tregs and the number of intestinal FOXP3+ cells did not correlate with clinical activity of the disease, as well as with endoscopic and histopathologic scoring. No significant correlation was found between the percentage of peripheral CD4+CD25^highFOXP3+ cells and the number of intestinal FOXP3+cells.

CONCLUSIONS

Children with IBD likely do not present with a quantitative deficiency of circulating and intestinal Tregs at the moment of diagnosis.

CD4(+)CD25(+)CD127(-) and CD4(+)CD25(+)Foxp3(+) Regulatory T Cell Subsets in Mediating Autoimmune Reactivity in Systemic Lupus Erythematosus Patients

The available clinical as well as experimental studies implicate participation of T regulatory (Treg) subsets in the pathogenesis and course of systemic lupus erythematosus (SLE). Introduction of the CD4(+)CD25(+)CD127(-) and CD4(+)CD25(+)Foxp3(+) regulatory subpopulations analysis into immunological processes assessment and disease activation prognosis in patients with lupus nephritis (LN) may improve monitoring of disease activity and enable an early, and thus more effective, therapeutic treatment. The main goal of the study was to investigate whether the quantitative changes of Treg subpopulations are related to the clinical status of patients with LN. Fifty-four adult SLE patients divided into two groups according to their SLEDAI and renal SLEDAI scores were enrolled into the study. Subpopulations of CD4(+)CD25(+)CD127(-) and CD4(+)CD25(+)Foxp3(+) phenotypes were determined by flow cytometry. The control group had higher absolute number of CD4(+)CD25(+)Foxp3(+) cells compared with the study group (p < 0.001). Also, significant inverse correlation in the absolute number of CD4(+)CD25(+)Foxp3(+) cells and SLEDAI score was observed. There were significant differences in the percentage and absolute number of CD4(+)CD25(+)Foxp3(+) lymphocytes between active and non-active LN groups. The study group had statistically lower values of CD4(+)CD25(+)CD127(-) cells, both in the percentage (p < 0.001) as well as their absolute number (p = 0.014) compared to the control group. There were also statistically significant positive correlations between the absolute number of CD4(+)CD25(+)CD127(-) and CD4(+)CD25(+)Foxp3(+) Tregs.

IN CONCLUSION

(1) reduction in the number of regulatory CD4(+)CD25(+)Foxp3(+) cells is a promising indicator of the activity of SLE, particularly of renal involvement; (2) determination of the number of regulatory cells using the CD4(+)CD25(+)CD127(-) phenotype is unreliable in patients with SLE.

Complement C4 induces regulatory T cells differentiation through dendritic cell in systemic lupus erythematosus

Background

Systemic lupus erythematosus (SLE) is a prototypic systemic autoimmune disease. Complement component 4 (C4) has be proved to play a role in pathogenesis of SLE. In the present study, we investigated the effect of C4 on T cells differentiation.

Methods

Thirty SLE patients were included in this study. CD4+ T cells were isolated from healthy subjects, and dendritic cells (DCs) were isolated from healthy subjects or SLE patients. C4 was supplemented to co-incubate with T cells and DCs.

Results

Serum C4 concentration was positively correlated with regulatory T cell (Treg) percentage (R² = 0.5907, p < 0.001) and TGFβ concentration (R² = 0.5641, p < 0.001) in SLE patients. Different concentrations of C4 had no effect on T cells differentiation. Co-incubated T cells with DCs and C4 for 7 days, the Treg percentage and TGF-β concentration were significantly elevated. In addition, pre-treated DCs (from healthy subjects or SLE patients) with C4 and then co-incubated with T cells, the increases of Treg percentage and TGF-β concentration were also observed.

Conclusion

C4 takes part in T cells differentiation to Treg cells via DCs.

Extracorporeal photopheresis as a therapy for autoimmune diseases

Systemic autoimmune diseases (AID) have multiorgan, heterogeneous clinical presentations and are characterized by dysregulation of the immune system, immunodeficiency, irreversible organ damage and increased morbidity and mortality. Preventing or decreasing flares of AID correlate with durable disease control, significant reduction of inflammation and prevention of disability or therapy-related toxicity. There is an urgent need for better treatment of severe, therapy-refractory AID. Extracorporeal photopheresis (ECP) is a cell-based immunomodulatory treatment which has been extensively used in variety of autoimmune disorders for the last two decades. ECP treatment is FDA approved for the treatment of cutaneous T-cell lymphoma (CTCL) with particularly promising results seen in graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (HCT). Prolonged therapy is safe, well tolerated and allows reduction of systemic immunosuppression in therapy-refractory patients. Both clinical and experimental evidence suggest that ECP mechanism of action is characterized by apoptosis and phagocytosis of activated cells by antigen-presenting cells (APC), secretion of anti-inflammatory cytokines and stimulation of regulatory T cells (Tregs). The focus of this paper is to review the current evidence of ECP use in the treatment of AID. Here, we summarize the experience of nine major AID from 65 published reports. The key findings demonstrate substantial evidence of ECP feasibility, safety and in some AID also promising efficacy. However, the role of ECP in AID therapy is not established as most published studies are retrospective with limited number of patients and the trials are small or poorly standardized. The available data support future investigations of ECP as a therapeutic modality for the treatment of AID in well-designed prospective clinical studies. J

GITR+ regulatory T cells in the treatment of autoimmune diseases

Autoimmune diseases decrease life expectancy and quality of life for millions of women and men. Although treatments can slow disease progression and improve quality of life, all currently available drugs have adverse effects and none of them are curative; therefore, requiring patients to take immunosuppressive drugs for the remainder of their lives. A curative therapy that is safe and effective is urgently needed. We believe that therapies promoting the in vivo expansion of regulatory T cells (Tregs) or injection of in vitro expanded autologous/heterologous Tregs (cellular therapy) can alter the natural history of autoimmune diseases. In this review, we present data from murine and human studies suggesting that 1) glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) plays a crucial role in thymic Treg (tTreg) differentiation and expansion; 2) GITR plays a crucial role in peripheral Treg (pTreg) expansion; 3) in patients with Sjögren syndrome and systemic lupus erythematosus, CD4(+)GITR(+) pTregs are expanded in patients with milder forms of the disease; and 4) GITR is superior to other cell surface markers to differentiate Tregs from other CD4(+) T cells. In this context, we consider two potential new approaches for treating autoimmune diseases consisting of the in vivo expansion of GITR(+) Tregs by GITR-triggering drugs and in vitro expansion of autologous or heterologous GITR(+) Tregs to be infused in patients. Advantages of such an approach, technical problems, and safety issues are discussed.

Expansion of regulatory GITR+CD25 low/-CD4+ T cells in systemic lupus erythematosus patients

Introduction

CD4⁺CD25^low/-GITR⁺ T lymphocytes expressing forkhead box protein P3 (FoxP3) and showing regulatory activity have been recently described in healthy donors. The objective of the study was to evaluate the proportion of CD4⁺CD25^low/-GITR⁺ T lymphocytes within CD4⁺ T cells and compare their phenotypic and functional profile with that of CD4⁺CD25^highGITR⁻ T lymphocytes in systemic lupus erythematosus (SLE) patients.

Methods

The percentage of CD4⁺CD25^low/-GITR⁺ cells circulating in the peripheral blood (PB) of 32 patients with SLE and 25 healthy controls was evaluated with flow cytometry. CD4⁺CD25^low/-GITR⁺ cells were isolated with magnetic separation, and their phenotype was compared with that of CD4⁺CD25^highGITR⁻ cells. Regulatory activity of both cell subsets was tested in autologous and heterologous co-cultures after purification through a negative sorting strategy.

Results

Results indicated that CD4⁺CD25^low/-GITR⁺ cells are expanded in the PB of 50% of SLE patients. Expansion was observed only in patients with inactive disease. Phenotypic analysis demonstrated that CD4⁺CD25^low/-GITR⁺ cells display regulatory T-cell (Treg) markers, including FoxP3, cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), transforming growth factor-beta (TGF-β), and interleukin (IL)-10. In contrast, CD4⁺CD25^highGITR⁻ cells appear to be activated and express low levels of Treg markers. Functional experiments demonstrated that CD4⁺CD25^low/-GITR⁺ cells exert a higher inhibitory activity against both autologous and heterologous cells as compared with CD4⁺CD25^highGITR⁻ cells. Suppression is independent of cell contact and is mediated by IL-10 and TGF-β.

Conclusions

Phenotypic and functional data demonstrate that in SLE patients, CD4⁺CD25^low/-GITR⁺ cells are fully active Treg cells, possibly representing peripheral Treg (pTreg) that are expanded in patients with inactive disease. These data may suggest a key role of this T-cell subset in the modulation of the abnormal immune response in SLE. Strategies aimed at expanding this Treg subset for therapeutic purpose deserve to be investigated.

Pathogenesis and potential therapeutic targets in systemic lupus erythematosus: from bench to bedside

Systemic lupus erythematosus (SLE) is considered an autoimmune disease with multiorgan involvement. Many advances have been made during the last decade regarding inflammatory pathways, genetic and epigenetic alterations, adaptive and innate immune system mechanisms specifically involved in SLE pathogenesis. Apoptosis has been proposed as an important player in SLE pathogenesis more than a decade ago. However, only recently new key apoptotic pathways have been investigated and the link between apoptotic debris containing autoantigens, innate immunity and ongoing inflammation has been further elucidated. Better understanding of cellular mechanisms and involved cytokines contributed to the development of new biological drugs specifically addressed for SLE therapy.

Peripheral CD4+ cell prevalence and pleuropulmonary manifestations in systemic lupus erythematosus patients

INTRODUCTION

Systemic lupus erythematosus (SLE) is an autoimmune disease involving several organs, including the lungs. Previous results confirmed changes of peripheral T cell subsets in lupus patients; however no data are available about their possible relationship with pulmonary involvement.

OBJECTIVE

To determine pulmonary manifestations and potential relationship in changes of peripheral CD4+ T cell subsets.

METHODS

Patients with SLE (N = 28) were enrolled in complex pulmonary examination. Patients were divided into groups with pleuropulmonary manifestations (SLEpulm N = 13 age: 44.9 ± 3.3 years, female: male = 11:2) or without (SLEc N = 15 age: 27.2 ± 3.7 years, female: male = 12:3). Peripheral blood was taken for T helper (Th)1, Th2, Th17, CD4+CD25hi+ and regulatory T (Treg: CD4+CD25hi+ CD127-) cell analysis from SLE patients and healthy volunteers (controls, N = 40).

RESULTS

SLEpulm patients were older, had more pulmonary symptoms and significantly decreased pO2 as compared to SLEc group. Ventilatory disorder was present in 92% of SLEpulm patients, with significantly decreased lung volumes, signs of airway involvement and decrease in DLco. Significant increase in Th1/Th2, while decrease in Th17/Treg ratios was present in all SLE compared to controls. In SLEpulm CD4+CD25hi+ subset without changes in Treg number was significantly increased as compared to SLEc and this subgroup of T cell showed significant positive correlation with dynamic lung function parameters and DLco (p < 0.05).

CONCLUSION

In lupus patients pleuropulmonary manifestations are prevalent and lung function and blood gas measurements should be regularly performed in the daily clinical assessment. Significant increase of activated CD4+CD25hi+ T cells, but not Treg is associated with decreased lung function parameters in SLEpulm patients.

Lupus nephritis: the evolving role of novel therapeutics

Immune complex accumulation in the kidney is the hallmark of lupus nephritis and triggers a series of events that result in kidney inflammation and injury. Cytotoxic agents and corticosteroids are standard of care for lupus nephritis treatment, but are associated with considerable morbidity and suboptimal outcomes. Recently, there has been interest in using novel biologic agents and small molecules to treat lupus nephritis. These therapies can be broadly categorized as anti-inflammatory (laquinamod, anti-tumor necrosis factor-like weak inducer of apotosis, anti-C5, and retinoids), antiautoimmunity (anti-CD20, anti-interferon α, and costimulatory blockers), or both (anti-interleukin 6 and proteasome inhibitors). Recent lupus nephritis clinical trials applied biologics or small molecules of any category to induction treatment, seeking short-term end points of complete renal response. These trials in general have not succeeded. When lupus nephritis comes to clinical attention during the inflammatory stage of the disease, the autoimmune stage leading to kidney inflammation will have been active for some time. The optimal approach for using novel therapies may be to initially target kidney inflammation to preserve renal parenchyma, followed by suppression of autoimmunity. In this review, we discuss novel lupus nephritis therapies and how they fit into a combinatorial treatment strategy based on the pathogenic stage.

Imbalance of different types of CD4(+) forkhead box protein 3 (FoxP3)(+) T cells in patients with new-onset systemic lupus erythematosus

The aim of this study was to examine the numbers of CD4(+) CD25(-) forkhead box protein 3 (FoxP3)(+) , CD4(+) CD25(+) FoxP3(+) and CD4(+) CXCR5(+) FoxP3(+) T cells in patients with new-onset systemic lupus erythematosus (SLE). The numbers of CD4(+) CD25(-) FoxP3(+) , CD4(+) CD25(+) FoxP3(+) and CD4(+) CXCR5(+) FoxP3(+) T cells and the concentrations of serum interleukin (IL)-10 in 23 patients and 20 healthy controls (HC) were measured. The potential correlations between CD4(+) FoxP3(+) T cells, serum IL-10 and clinical measures in SLE patients were analysed. In comparison with that in the HC, significantly reduced numbers of CD4(+) CD25(+) FoxP3(+) and CD4(+) CXCR5(+) FoxP3(+) T cells, but increased numbers of CD4(+) CD25(-) FoxP3(+) T cells, were detected, accompanied by significantly lower levels of serum IL-10 in the patients. Stratification analysis indicated the numbers of CD4(+) CD25(+) FoxP3(+) and CD4(+) CXCR5(+) FoxP3(+) T cells and serum IL-10 levels in the patients with seropositive anti-dsDNA were significantly less than that in those with seronegative anti-dsDNA. Treatment with the anti-SLE therapy, particularly with prednisone, leflunomide and methotrexate, significantly improved the imbalance of these types of FoxP3(+) T cells and increased the concentrations of serum IL-10 in the drug-responding patients. The numbers of CD4(+) CD25(+) FoxP3(+) T cells were correlated negatively with the values of SLE disease activity index (SLEDAI), whereas the numbers of CD4(+) CD25(-) FoxP3(+) T cells were correlated positively with the values of SLEDAI, erythrocyte sedimentation rate (ESR) and serum C3. In addition, the concentrations of serum IL-10 were correlated positively with the numbers of CD4(+) CD25(+) FoxP3(+) T cells, but negatively with the values of SLEDAI, serum C3, CRP and ESR in these patients. Our data indicate that the imbalance of different types of FoxP3(+) CD4(+) T cells may contribute to the development of SLE in Chinese patients.

Differential expression of CD30 on CD3 T lymphocytes in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune systemic disease caused as a result of an imbalance of Th1-/Th2-type cytokines. The soluble form of CD30 (CD30s) released from peripheral blood cells has been described as a marker of active disease in Th2-type immune response as in SLE. However, the expression of CD30 on CD3 T lymphocytes from patients with SLE has not been studied yet. Therefore, we have addressed our study to attempt this issue, studying CD30 expression by flow cytometry on CD3 T lymphocytes and CD4/CD8 subsets in samples from SLE patients mainly with lupus nephritis. In parallel, we have determined the production of the cytokines IL-4 (Th2), IFNγ (Th1), IL-10 and TGFβ by intracellular staining. Differences between positive CD30 T cells in healthy controls and patients with SLE were found, with a higher percentage of CD30-expressing T cells in patients with SLE (P = 0.001). In contrast to healthy controls, CD30 was mainly expressed on CD8 T cells from patients with SLE. The intracellular cytokine staining showed that TGFβ is the main cytokine expressed in CD3 T cells from patients with SLE. In addition to this, we have found a positive correlation between CD30-expressing T cells and IL-4, IFNγ, and immunosuppressive cytokines (IL-10 and TGFβ) (P < 0.05). These results suggest that CD30 could play a role in the pathogenesis of SLE and its expression on CD3 T lymphocytes is not restricted only to Th2-type response.

Systemic lupus erythematosus: immunopathogenesis and novel therapeutic targets

Systemic lupus erythematosus (SLE) is the prototype of autoimmune diseases with multiorgan involvement. SLE presents many genetic and epigenetic associations and the pathogenesis is characterized by a complex network of alterations affecting both adaptative and innate immunity. The disclosure of novel mechanisms of SLE pathogenesis suggested new therapeutic targets, based on interference with the cytokine pathways or on depletion of the immune cells.

Importance of regulatory T cells in the pathogenesis of psoriasis: review of the literature

Psoriasis is a common chronic relapsing inflammatory cutaneous disease; the main role in the inflammation of this condition is played by lymphocyte Th1, Th17 and their cytokines. The activity of these cells is modulated by a particular kind of T cells recently described: the T regulatory cells (Treg). These are able to inhibit the immunological response and to maintain the cutaneous immunological homeostasis, thus preventing autoimmunity against self antigens. Few data are available in the literature as to Treg in psoriasis; several studies demonstrate that the function of these cells is impaired in this condition and treatments for psoriasis may increase the number and activity of Treg. The role of these cells in the pathogenesis of psoriasis is very important to understand how they may contribute to the development of this cutaneous disorder. In the near future it would be possible to target therapies at these defects, improving the activity of these cells and maintaining cutaneous homeostasis, preventing psoriasis or other inflammatory cutaneous conditions.

Carbon monoxide exposure improves immune function in lupus-prone mice

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by multiple alterations affecting the normal function of immune cells, such as lymphocytes, dendritic cells (DCs) and monocytes. Although the understanding of autoimmunity has significantly increased, the breakthrough in effective therapies has been modest, making necessary the development of new therapeutic strategies. Here we propose that a new potential target for therapy is haem oxygenase-1 (HO-1), an enzyme that catalyses the degradation of the haem group into biliverdin, carbon monoxide (CO) and Fe(2+) . These products exhibit immunosuppressive and anti-inflammatory effects, which can contribute to improving tolerance during organ transplantation. Because HO-1 is highly expressed by immune cells involved in SLE pathogenesis, such as monocytes and DCs, we evaluated whether induction of HO-1 expression or the administration of CO could ameliorate disease in the FcγRIIb knockout (KO) mouse model for SLE. We found that CO administration decreased the expansion of CD11b(+) cells, prevented the decline of regulatory T cells and reduced anti-histone antibodies observed in untreated FcγRIIb KO mice. Furthermore, CO-treated animals and HO-1 induction showed less kidney damage compared with untreated mice. These data suggest that HO-1 modulation and CO administration can ameliorate autoimmunity and prevent the lupus symptoms shown by FcγRIIb KO mice, highlighting HO-1 as a potential new target for autoimmune therapy.

Immunopathogenic mechanisms of systemic autoimmune disease

Systemic lupus erythematosus, Sjögren's syndrome, and dermatomyositis are systemic autoimmune diseases that develop after environmental triggering of genetically susceptible individuals. The precise cellular and molecular mechanisms leading to autoimmune disease, and what factors determine which organs are involved, remain poorly understood. Recent insights into genetic susceptibility now make obvious that environmental triggers often act via cellular pathways containing disease-associated polymorphisms. In the breaking of tolerance, the initiating tissue--including dendritic cells--provides a decisive microenvironment that affects immune-cell differentiation, leading to activation of adaptive immunity. Type 1 interferon produced by innate immune cells has a central role in systemic autoimmunity and activates B cells and T cells. In turn, B-cell-derived autoantibodies stimulate dendritic cells to produce type 1 interferon; thus, a positive feedforward loop is formed that includes both the innate and adaptive systems. New treatments could simultaneously and specifically target several such vital pathways in autoimmunity.

Regulatory T cells in systemic lupus erythematosus and pregnancy

Systemic lupus erythematosus (SLE) is a chronic multisystem autoimmune disorder that predominantly affects women of reproductive age. As clinical outcomes improve, pregnancy in these women is becoming more common. Although epidemiological data have documented an improvement in the prognosis of pregnancy in these women over recent years, they are still at significantly increased risk of pregnancy complications, such as miscarriage, stillbirth, pre-eclampsia and impaired foetal growth. The pathogenesis of SLE involves marked immune dysfunction, and in particular, the function of immunosuppressive elements of the immune system is impaired, including regulatory T-cell function. Because regulatory T cells are likely to be the key cell-modulating feto-maternal tolerance, this review overviews the possibility that regulatory T-cell impairments contribute to pregnancy pathology in women with SLE and contribute to the clinical challenge of managing these women during pregnancy.

Th1/Th2 cytokine profile in childhood-onset systemic lupus erythematosus

OBJECTIVE

To determine the serum levels of Th1 (IL-12, IFN-γ,TNF-α) and Th2 (IL-5, IL-6 and IL-10) cytokines in childhood-onset SLE, first-degree relatives and healthy controls. To elucidate their association with disease activity, laboratory and treatment features.

METHODS

We included 60 consecutive childhood-onset SLE patients [median age 18 years (range 10-37)], 64 first-degree relatives [median 40 (range 28-52)] and 57 healthy [median age 19 years (range 6-30 years)] controls. Controls were age and sex-matched to SLE patients. SLE patients were assessed for clinical and laboratory SLE manifestations, disease activity (SLEDAI), damage (SDI) and current drug exposures. Mood and anxiety disorders were determined through Becks Depression (BDI) and Anxiety Inventory (BAI). Th1 (IL-12, IFN-γ,TNF-α) and Th2 (IL-5, IL-6 and IL-10) cytokines levels were measured by ELISA and compared by non-parametric tests.

RESULTS

Serum TNF-α (p=0.004), IL-6 (p=0.007) and IL-10 (p=0.03) levels were increased in childhood-onset SLE patients when compared to first-degree relatives and healthy controls. TNF-α levels were significantly increased in patients with active disease (p=0.014) and correlated directly with SLEDAI scores (r=0.39; p=0.002). IL-12 (p=0.042) and TNF-α (p=0.009) levels were significantly increased in patients with nephritis and TNF-α in patients with depression (p=0.001). No association between cytokine levels and SDI scores or medication was observed.

CONCLUSION

Th1 cytokines may play a role in the pathogenesis of neuropsychiatric and renal manifestations in childhood-onset SLE. The correlation with SLEDAI suggests that TNF-α may be a useful biomarker for disease activity in childhood-onset SLE, however longitudinal studies are necessary to determine if increase of this cytokine may predict flares in childhood-onset SLE.

Relationship between FOXP3 positive populations and cytokine production in systemic lupus erythematosus

In this work we studied CD4+FOXP3+ populations in systemic lupus erythematosus (SLE) and the relationship with Th cytokine production. We found an increment in CD25-FOXP3+ population in SLE associated with CD4+ downregulation and disease progression. CD25low cells were also upregulated and showed increased percentages of FOXP3+ and CD127-/low cells, supporting the activated status of SLE lymphocytes. Despite the normal levels of CD25highFOXP3+ cells, the negative correlations observed in controls with the frequency of IFNγ, TNFα and IL-10 secreting cells were disrupted in patients, supporting a defective Treg function. Also, CD25high cells showed an altered balance in the production of these cytokines. In addition, CD25highFOXP3+ cells correlated directly with IL-17A and IL-8 but not with TGFβ in SLE. The increased proportion of IL-17+ cells among the CD25high subset and the positive correlation between IL-17 levels and Treg cells suggest a trans-differentiation of Treg into Th17 cells in SLE.

Pharmacological modulation of GITRL/GITR system: therapeutic perspectives

Glucocorticoid-induced TNFR-related (gitr) is a gene coding for a member of the TNF receptor superfamily. GITR activation by its ligand (GITRL) influences the activity of effector and regulatory T cells, thus participating in the development of immune response against tumours and infectious agents, as well as in autoimmune and inflammatory diseases. Notably, treating animals with GITR-Fc fusion protein ameliorates autoimmune/inflammatory diseases while GITR triggering, by treatment with anti-GITR mAb, is effective in treating viral, bacterial and parasitic infections, as well in boosting immune response against tumours. GITR modulation has been indicated as one of the top 25 most promising research areas by the American National Cancer Institute, and a clinical trial testing the efficacy of an anti-GITR mAb in melanoma patients has been started. In this review, we summarize results regarding: (i) the mechanisms by which GITRL/GITR system modulates immune response; (ii) the structural and functional studies clearly demonstrating differences between GITRL/GITR systems of mice and humans; (iii) the molecules with pharmacological activities including anti-GITR mAbs, GITR-Fc and GITRL-Fc fusion proteins, GITRL in monomer or multimer conformation; and (iv) the possible risks deriving from GITRL/GITR system pharmacological modulation. In conclusion, GITR triggering and inhibition could be useful in treating tumours, infectious diseases, as well as autoimmune and inflammatory diseases. However, differences between mouse and human GITRL/GITR systems suggest that further preclinical studies are needed to better understand how safe therapeutic results can be obtained and to design appropriate clinical trials.

Balance between regulatory T and Th17 cells in systemic lupus erythematosus: the old and the new

Pathogenic mechanisms underlying the development of systemic lupus erythematosus (SLE) are very complex and not yet entirely clarified. However, the pivotal role of T lymphocytes in the induction and perpetuation of aberrant immune response is well established. Among T cells, IL-17 producing T helper (Th17) cells and regulatory T (Treg) cells represent an intriguing issue to be addressed in SLE pathogenesis, since an imbalance between the two subsets has been observed in the course of the disease. Treg cells appear to be impaired and therefore unable to counteract autoreactive T lymphocytes. Conversely, Th17 cells accumulate in target organs contributing to local IL-17 production and eventually tissue damage. In this setting, targeting Treg/Th17 balance for therapeutic purposes may represent an intriguing and useful tool for SLE treatment in the next future. In this paper, the current knowledge about Treg and Th17 cells interplay in SLE will be discussed.

GITR-expressing regulatory T-cell subsets are increased in tumor-positive lymph nodes from advanced breast cancer patients as compared to tumor-negative lymph nodes

Lymph node (LN) infiltration by neoplastic process involves important changes in lymph node immune microenvironment. In particular, regulatory T cells (Treg) seem to have a key role in altering the immunoediting function of the immune system which leads to the elusion of the tumor from immune surveillance. In this study, we evaluated the expression of T-cell markers in CD4+ and CD8+ subsets from tumor-positive and tumor-negative lymph nodes from the same, advanced stage breast cancer patient. The study was carried out on 3 patients and similar results were obtained. Flow cytometric analysis of CD8+ cells demonstrated a significant difference in the expression of CD25, CD45RA, CD45RO, and GITRL (Glucocorticoid-Induced TNF receptor-Related ligand). Flowcytometric analysis of CD4+ cells demonstrated a significant difference in the expression of GITR (Glucocorticoid-Induced TNF receptor-Related), CD25, FoxP3 (Forkhead box P3), CD28, and CD45RA. Multiple staining allowed the identification of two Treg subpopulations, CD4+ CD25 highGITR+ CD127-/low and CD4+ CD25 low GITR+ CD127+ cells, proving that both are increased in the positive nodes in comparison with the negative nodes from the same patient. We identified for the first time the CD4+ CD25 low GITR+ CD127+ Treg subpopulation in cancer, and the 2.6 fold increase in positive LN suggests that this Treg subpopulation could be a key player in metastasis. We also found GITRL expression in the CD8 lymphocytes, which may also contribute to the changes of metastatic lymph node microenvironment. These findings make both GITR and GITRL good possible co-candidates for future therapeutical intervention against metastasis and perhaps also as disease evolution biomarkers.

CD8+ T cells: GITR matters

As many members of the tumor necrosis factor receptor superfamily, glucocorticoid-induced TNFR-related gene (GITR) plays multiple roles mostly in the cells of immune system. CD8⁺ T cells are key players in the immunity against viruses and tumors, and GITR has been demonstrated to be an essential molecule for these cells to mount an immune response. The aim of this paper is to focus on GITR function in CD8⁺ cells, paying particular attention to numerous and recent studies that suggest its crucial role in mouse disease models.

Role of CREM in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease. Immune complex, autoantibodies and autoreactive lymphocytes are involved in manifestations of SLE. Recently, investigations have indicated that expression of the transcription factor cAMP responsive element modulator (CREM) is abnormal in T cells and might play an important role in the pathogenesis of SLE. CREM has much influence on the promoters, such as IL-2, c-fos, TCR ζ, and SYK. Moreover, activity of CREM itself has been demonstrated, particularly with an auto-regulatory feedback mechanism. Therefore, we will discuss the association of CREM and SLE based on current knowledge to unravel the mechanism of CREM performance.

Increased CD45RA+ FoxP3(low) regulatory T cells with impaired suppressive function in patients with systemic lupus erythematosus

BACKGROUND

The role of naturally occurring regulatory T cells (Treg) in the control of the development of systemic lupus erythematosus (SLE) has not been well defined. Therefore, we dissect the phenotypically heterogeneous CD4(+)FoxP3(+) T cells into subpopulations during the dynamic SLE development. METHODLOGY/PRINCIPAL FINDINGS: To evaluate the proliferative and suppressive capacities of different CD4(+) T cell subgroups between active SLE patients and healthy donors, we employed CD45RA and CD25 as surface markers and carboxyfluorescein diacetatesuccinimidyl ester (CFSE) dilution assay. In addition, multiplex cytokines expression in active SLE patients was assessed using Luminex assay. Here, we showed a significant increase in the frequency of CD45RA(+)FoxP3(low) naive Treg cells (nTreg cells) and CD45RA(-)FoxP3(low) (non-Treg) cells in patients with active SLE. In active SLE patients, the increased proportions of CD45RA(+)FoxP3(low) nTreg cells were positively correlated with the disease based on SLE disease activity index (SLEDAI) and the status of serum anti-dsDNA antibodies. We found that the surface marker combination of CD25(+)CD45RA(+) can be used to defined CD45RA(+)FoxP3(low) nTreg cells for functional assays, wherein nTreg cells from active SLE patients demonstrated defective suppression function. A significant correlation was observed between inflammatory cytokines, such as IL-6, IL-12 and TNFα, and the frequency of nTreg cells. Furthermore, the CD45RA(+)FoxP3(low) nTreg cell subset increased when cultured with SLE serum compared to healthy donor serum, suggesting that the elevated inflammatory cytokines of SLE serum may promote nTreg cell proliferation/expansion.

CONCLUSIONS/SIGNIFICANCE

Our results indicate that impaired numbers of functional CD45RA(+)FoxP3(low) naive Treg cell and CD45RA(-)FoxP3(low) non-suppressive T cell subsets in inflammatory conditions may contribute to SLE development. Therefore, analysis of subsets of FoxP3(+) T cells, using a combination of FoxP3, CD25 and CD45RA, rather than whole FoxP3(+) T cells, will help us to better understand the pathogenesis of SLE and may lead to the development of new therapeutic strategies.

Lupus nephritis: an overview of recent findings

Lupus nephritis (LN) is one of the most serious complications of systemic lupus erythematosus (SLE) since it is the major predictor of poor prognosis. In susceptible individuals suffering of SLE, in situ formation and deposit of immune complexes (ICs) from apoptotic bodies occur in the kidneys as a result of an amplified epitope immunological response. IC glomerular deposits generate release of proinflammatory cytokines and cell adhesion molecules causing inflammation. This leads to monocytes and polymorphonuclear cells chemotaxis. Subsequent release of proteases generates endothelial injury and mesangial proliferation. Presence of ICs promotes adaptive immune response and causes dendritic cells to release type I interferon. This induces maturation and activation of infiltrating T cells, and amplification of Th2, Th1 and Th17 lymphocytes. Each of them, amplify B cells and activates macrophages to release more proinflammatory molecules, generating effector cells that cannot be modulated promoting kidney epithelial proliferation and fibrosis. Herein immunopathological findings of LN are reviewed.

Regulatory T cells: banned cells for decades

Regulatory T cells (Tregs), either thymic derived or peripherally induced, suppress a variety of physiological and pathological immune responses, and the absence of this cell subset has been shown to result in severe systemic autoimmunity. Since their acceptance almost two decades ago, intensive research aiming to characterize the phenotype, to elucidate the suppressive activity, and to decipher the migratory behavior of Tregs has been performed. A substantial number of studies, however, focused on understanding whether defects in Treg numbers and function contribute to the development and progression of inflammatory, autoimmune, and malignant disorders, and how Treg numbers/function might be modulated to treat patients with autoimmune diseases or cancer. In the skin, an organ that is constantly exposed to the environment, Tregs are known to be critically involved not only in the maintenance of skin homeostasis but also in the regulation of cutaneous immune responses. In this review, we present an overview on recent data concerning Treg development and expansion, the molecular mechanisms underlying their immunosuppressive activity, and the modulation of Treg function. Furthermore, we discuss the role of Tregs in cutaneous inflammatory and autoimmune disorders.

CD4+FOXP3+ T regulatory cells in human autoimmunity: more than a numbers game

Regulatory T cells (Treg) play a dominant role in suppression of autoimmune pathology, as rescue of Treg number and/or function in model systems can both prevent and reverse disease. These findings have generated a series of studies addressing the role of defects in Treg number and function in human autoimmunity. However, demonstrating global defects in Treg of individuals diagnosed with autoimmune diseases has been challenging. These challenges are founded, in part, in the complexity of human autoimmune diseases in which various genetic factors and environmental triggers contribute to disease susceptibility. Moreover, contribution of failed Treg-mediated suppression to pathogenesis can extend to multiple mechanisms. In this article, we discuss what is known with respect to the number and function of CD4(+)FOXP3(+) Treg in human autoimmunity, focusing on representative autoimmunediseases in which there are diverse Treg-mediated defects. We also highlight the need to better understand Treg plasticity and function in the context of autoimmunity.

Regulatory T cells in systemic lupus erythematosus (SLE); role of peptide tolerance

Regulatory T cells play an important role in the maintenance and regulation of immune tolerance and in the prevention of autoimmunity. Recent studies have demonstrated a deficiency in number and function of regulatory T cells in lupus and other autoimmune diseases. This may contribute to immune dysregulations and a defect in self-tolerance mechanisms. How to balance and "reset" the immune response from harmful pro-inflammatory to beneficial anti-inflammatory is the current strategy of the research. In this regard, several studies have been performed with various peptides, drugs, steroids and epigenetic agents to induce or modify regulatory cells and some measure of success has been achieved in the animal model of SLE and with lupus patient cells. Challenges ahead include the heterogeneous nature, phenotype and function of regulatory cells and the difficulties in manipulation of regulatory function in healthy versus diseased states. In this review, we will provide some recent findings indicating challenges and potential benefits of targeting of regulatory T cells in lupus.

1H NMR-based metabolomic study of metabolic profiling for systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic inflammatory disease characterized by multi-system involvement, diverse clinical presentation, and alterations in circulating metabolites. In this study, a 1H NMR spectroscopy-based metabolomics approach was applied to establish a human SLE serum metabolic profile. Serum samples were obtained from patients with SLE ( n = 64), patients with rheumatoid arthritis (RA) ( n = 30) and healthy controls ( n = 35). The NOESYPR1D spectrum combined with multi-variate pattern recognition analysis was used to cluster the groups and establish a disease-specific metabolites phenotype. Principal component analysis (PCA) and orthogonal partial least-squares discriminant analysis (OPLS-DA) models were capable of distinguishing SLE or RA patients from healthy subjects. The OPLS-DA model was able to predict diagnosis of SLE with a sensitivity rate of 60.9% and a specificity rate of 97.1%. For diagnosing RA, the model has much higher sensitivity (96.7%) and specificity (91.4%). The SLE serum samples were characterized by reduced concentrations of valine, tyrosine, phenylalanine, lysine, isoleucine, histidine, glutamine, alanine, citrate, creatinine, creatine, pyruvate, high-density lipoprotein, cholesterol, glycerol, formate and increased concentrations of N-acetyl glycoprotein, very low-density lipoprotein and low-density lipoprotein in comparison with the control population. Theresults not only indicated that serum NMR-based metabolomic methods had sufficient sensitivity and specificity to distinguish SLE and RA from healthy controls, but also have the potential to be developed into a clinically useful diagnostic tool, and could also contribute to a further understanding of disease mechanisms.

The glucocorticoid-induced TNF receptor family-related protein (GITR) is critical to the development of acute pancreatitis in mice

BACKGROUND AND PURPOSE

Pancreatitis represents a life-threatening inflammatory condition where leucocytes, cytokines and vascular endothelium contribute to the development of the inflammatory disease. The glucocorticoid-induced tumour necrosis factor (TNF) receptor family-related protein (GITR) is a costimulatory molecule for T lymphocytes, modulates innate and adaptive immune system and has been found to participate in a variety of immune responses and inflammatory processes. Our purpose was to verify whether inhibition of GITR triggering results in a better outcome in experimental pancreatitis.

EXPERIMENTAL APPROACH

In male GITR knock-out (GITR(-/-)) and GITR(+/+) mice on Sv129 background, acute pancreatitis was induced after i.p. administration of cerulein. Other experimental groups of GITR(+/+) mice were also treated with different doses of Fc-GITR fusion protein (up to 6.25 µg·mouse⁻¹), given by implanted mini-osmotic pump. Clinical score and pro-inflammatory parameters were evaluated.

KEY RESULTS

A less acute pancreatitis was found in GITR(-/-) mice than in GITR(+/+) mice, with marked differences in oedema, neutrophil infiltration, pancreatic dysfunction and injury. Co-treatment of GITR(+/+) mice with cerulein and Fc-GITR fusion protein (6.25 µg·mouse⁻¹) decreased the inflammatory response and tissue injury, compared with treatment with cerulein alone. Inhibition of GITR triggering was found to modulate activation of nuclear factor κB as well as the production of TNF-α, interleukin-1β, inducible nitric oxide synthase, nitrotyrosine, poly-ADP-ribose, intercellular adhesion molecule-1 and P-selectin.

CONCLUSIONS AND IMPLICATIONS

The GITR-GITR ligand system is crucial to the development of acute pancreatitis in mice. Our results also suggest that the Fc-GITR fusion protein could be useful in the treatment of acute pancreatitis.

HDAC inhibition in lupus models

Systemic lupus erythematosus (SLE) is a prototypic autoimmune inflammatory disease characterized by the production of autoantibodies directed against nuclear antigens such as nucleosomes, DNA and histone proteins found within the body's cells and plasma. Autoantibodies may induce disease by forming immune complexes that lodge in target organs or by crossreacting with targeted antigens and damaging tissue. In addition to autoantibody production, apoptotic defects and impaired removal of apoptotic cells contribute to an overload of autoantigens that initiate an autoimmune response. Besides the well-recognized genetic susceptibility to SLE, environmental and epigenetic factors play a crucial role in disease pathogenesis as evidenced by monozygotic twins typically being discordant for disease. Changes in DNA methylation and histone acetylation alter gene expression and are thought to contribute to the epigenetic deregulation in disease. In SLE, global and gene-specific DNA methylation changes have been demonstrated to occur. Additionally, aberrant histone acetylation is evident in individuals with SLE. Moreover, histone deacetylase inhibitors (HDACi) have been shown to reverse the skewed expression of multiple genes involved in SLE. In this review, we discuss the implications of epigenetic alterations in the development and progression of SLE, and how therapeutics designed to alter histone acetylation status may constitute a promising avenue to target disease.

Mechanisms of impaired regulation by CD4(+)CD25(+)FOXP3(+) regulatory T cells in human autoimmune diseases

A lack of regulatory T (T(Reg)) cells that express CD4, CD25 and forkhead box P3 (FOXP3) results in severe autoimmunity in both mice and humans. Since the discovery of T(Reg) cells, there has been intense investigation aimed at determining how they protect an organism from autoimmunity and whether defects in their number or function contribute to the development of autoimmunity in model systems. The next phase of investigation - that is, to define the role that defects in T(Reg) cells have in human autoimmunity - is now underway. This Review summarizes our progress so far towards understanding the role of CD4(+)CD25(+)FOXP3(+) T(Reg) cells in human autoimmune diseases and the impact that this knowledge might have on the diagnosis and treatment of these diseases.