C57BL/6 mice genetically deficient in IL-12/IL-23 and IFN-gamma are susceptible to experimental autoimmune myasthenia gravis, suggesting a pathogenic role of non-Th1 cells

Blocking interleukin-23 ameliorates neuromuscular and thymic defects in myasthenia gravis

Acetylcholine receptor (AChR) myasthenia gravis (MG) is a chronic autoimmune disease characterized by muscle weakness. The AChR⁺ autoantibodies are produced by B-cells located in thymic ectopic germinal centers (eGC). No therapeutic approach is curative. The inflammatory IL-23/Th17 pathway is activated in the thymus as well as in the blood and the muscle, contributing to the MG pathogenic events. We aimed to study a potential new therapeutic approach that targets IL-23p19 (IL-23) in the two complementary preclinical MG models: the classical experimental MG mouse model (EAMG) based on active immunization and the humanized mouse model featuring human MG thymuses engrafted in NSG mice (NSG-MG). In both preclinical models, the anti-IL-23 treatment ameliorated MG clinical symptoms. In the EAMG, the treatment reduced IL-17 related inflammation, anti-AChR IgG2b antibody production, activated transduction pathway involved in muscle regeneration and ameliorated the signal transduction at the neuromuscular junction. In the NSG-MG model, the treatment reduced pathogenic Th17 cell population and expression of genes involved in eGC stabilization and B-cell development in human MG thymus biopsies. Altogether, these data suggest that a therapy targeting IL-23p19 may promote significant clinical ameliorations in AChR⁺ MG disease due to concomitant beneficial effects on the thymus and skeletal muscle defects.

Role of Regulatory T Cells in Skeletal Muscle Regeneration: A Systematic Review

Muscle injuries are frequent in individuals with genetic myopathies and in athletes. Skeletal muscle regeneration depends on the activation and differentiation of satellite cells present in the basal lamina of muscle fibers. The skeletal muscle environment is critical for repair, metabolic and homeostatic function. Regulatory T cells (Treg) residing within skeletal muscle comprise a distinct and special cell population that modifies the inflammatory environment by secreting cytokines and amphiregulin, an epidermal growth factor receptor (EGFR) ligand that acts directly upon satellite cells, promoting tissue regeneration. This systematic review summarizes the current knowledge regarding the role of Treg in muscle repair and discusses their therapeutic potential in skeletal muscle injuries. A bibliographic search was carried out using the terms Treg and muscle regeneration and repair, covering all articles up to April 2021 indexed in the PubMed and EMBASE databases. The search included only published original research in human and experimental animal models, with further data analysis based on the PICO methodology, following PRISMA definitions and Cochrane guidelines.

Increased serum IL-36γ levels are associated with disease severity in myasthenia gravis patients

BACKGROUND

Interleukin 36 (IL-36), as a gradually recognized cytokine, is involved in the occurrence and evolution of autoimmune diseases. Nevertheless, the relationship between myasthenia gravis (MG) and IL-36 is rarely reported.

METHODS

We evaluated the serum levels of IL-36 (IL-36α, IL-36β and IL-36γ) by enzyme-linked immunosorbent assay (ELISA). Further, clinical parameters in 97 MG patients and 49 healthy controls (HCs) were carefully measured.

RESULTS

Serum IL-36γ levels were significantly elevated in the MG patients compared with the HCs (p < 0.0001). Compared to those in remission, patients in the acute phase exhibited higher levels of IL-36α and IL-36γ (p = 0.038 and p = 0.011, respectively). Furthermore, patients with generalized MG (GMG) exhibited markedly higher serum IL-36γ levels than those with ocular MG (OMG) (p = 0.003).

CONCLUSIONS

The serum levels of IL-36γ in patients with MG were increased and positively correlated with disease severity and may thus have potential as a serological MG marker.

Il-23/Th17 cell pathway: A promising target to alleviate thymic inflammation maintenance in myasthenia gravis

IL-23/Th17 pathway has been identified to sustain inflammatory condition in several autoimmune diseases and therefore being targeted in various therapeutic and effective approaches. Patients affected with autoimmune myasthenia gravis exhibit a disease effector tissue, the thymus, that harbors ectopic germinal centers that sustain production of auto-antibodies, targeting proteins located in the neuromuscular junction, cause of the organ-specific chronic autoimmune disease. The present study aims to investigate the IL-23/Th17 cell pathway in the thymic inflammatory and pathogenic events. We found that thymuses of MG patients displayed overexpression of Interleukin-17, signature cytokine of activated Th17 cells. This activation was sustained by a higher secretion of Interleukin-23 by TEC, in addition to the increased expression of cytokines involved in Th17 cell development. The overexpression of Interleukin-23 was due to a dysregulation of interferon type I pathway. Besides, Interleukin-17 secreted, and Th17 cells were localized around thymic ectopic germinal centers. These cells expressed podoplanin, a protein involved in B-cell maturation and antibody secretion. Finally, production of Interleukin-23 was also promoted by Interleukin-17 secreted itself by Th17 cells, highlighting a chronic loop of inflammation sustained by thymic cell interaction. Activation of the IL-23/Th17 pathway in the thymus of autoimmune myasthenia gravis patients creates an unstoppable loop of inflammation that may participate in ectopic germinal center maintenance. To alleviate the physio-pathological events in myasthenia gravis patients, this pathway may be considered as a new therapeutic target.

An imbalance between regulatory T cells and T helper 17 cells in acetylcholine receptor-positive myasthenia gravis patients

A chronic autoimmune disease, myasthenia gravis (MG) is characterized in 85% of patients by antibodies directed against the acetylcholine receptor (AChR) located at the neuromuscular junction. The functional and effective balance between regulatory T cells (T_reg cells) and effector T cells (T_eff cells) is lost in the hyperplastic thymus of MG patients with antibodies specific for the AChR (AChR⁺ MG patients). The objective of this review is to describe how T_reg cells and inflammatory T cells participate in this imbalance and contribute to induce a chronic inflammatory state in the MG thymus. We discuss the origins and characteristics of T_reg cells and their reported dysfunctions in AChR⁺ MG patients. We also review the inflammatory condition observed in MG thymus, including overexpression of interleukin (IL)-1β, IL-6, and IL-23, cytokines that promote the differentiation of T helper 17 (T_H 17) cells and the expression of IL-17. We summarize the preclinical models used to determine the implication of expression of cytokines, such as IL-6, IL-12 (IL-23 subunit), IL-17, and interferon γ to the development of experimental autoimmune MG. Finally, we suggest that biological agents, such as humanized monoclonal antibodies that target the IL-23/T_H 17 pathway, should be investigated in the context of MG, as they have proven efficiency in other autoimmune diseases.

NFAT1 Regulates Systemic Autoimmunity through the Modulation of a Dendritic Cell Property

The transcription factor NFAT1 plays a pivotal role in the homeostasis of T lymphocytes. However, its functional importance in non-CD4⁺ T cells, especially in systemic immune disorders, is largely unknown. In this study, we report that NFAT1 regulates dendritic cell (DC) tolerance and suppresses systemic autoimmunity using the experimental autoimmune myasthenia gravis (EAMG) as a model. Myasthenia gravis and EAMG are T cell-dependent, Ab-mediated autoimmune disorders in which the acetylcholine receptor is the major autoantigen. NFAT1-knockout mice showed higher susceptibility to EAMG development with enhanced Th1/Th17 cell responses. NFAT1 deficiency led to a phenotypic alteration of DCs that show hyperactivation of NF-κB-mediated signaling pathways and enhanced binding of NF-κB (p50) to the promoters of IL-6 and IL-12. As a result, NFAT1-knockout DCs produced much higher levels of proinflammatory cytokines such as IL-1β, IL-6, IL-12, and TNF-α, which preferentially induce Th1/Th17 cell differentiation. Our data suggest that NFAT1 may limit the hyperactivation of the NF-κB-mediated proinflammatory response in DCs and suppress autoimmunity by serving as a key regulator of DC tolerance.

ONX-0914, a selective inhibitor of immunoproteasome, ameliorates experimental autoimmune myasthenia gravis by modulating humoral response

Accumulating evidence shows that the immunoproteasome participates in the immune response, beyond its initial role in the protein degradation. Here, we tested the effects of the selective immunoproteasome inhibitor, ONX-0914, on experimental autoimmune myasthenia gravis (EAMG). We found that ONX-0914 ameliorated the severity of ongoing EAMG by reducing the autoantibody affinity, accompanied with decreased Tfh cells and antigen presenting cells. Also it reduced the percentage of Th17 cells and inhibited the secretion of IL-17. Our data indicated ONX-0914 may bring benefit for MG therapy.

Ablation of IL-17 expression moderates experimental autoimmune myasthenia gravis disease severity

An array of cytokines influences the pathogenesis of early onset myasthenia gravis (MG) and its animal model, experimental autoimmune myasthenia gravis (EAMG). Patients with MG, in particular those with more severe weakness, have elevations of the pro-inflammatory cytokine IL-17 in the blood. We assessed the role of IL-17A in autoimmunity by inducing EAMG in mice with knockout of IL-17 and found a reduction of EAMG severity, but not a complete ablation of disease. The IL-17^ko mice had no evidence of weakness, low levels of acetylcholine receptor antibodies, and retention of acetylcholine receptor at the neuromuscular junction. Splenic germinal center size was reduced in EAMG IL-17^ko mice along with elevations of Foxp3 and BCL-6 gene expression, suggesting a shift away from pro-inflammatory signals. The results emphasize the importance of IL-17 in EAMG development and that IL-17 independent pathways drive the autoimmune reaction.

Increased expression of P2X7 receptor in peripheral blood mononuclear cells correlates with clinical severity and serum levels of Th17-related cytokines in patients with myasthenia gravis

OBJECTIVES

P2X7R is a well-documented activator of innate and adaptive immune responses. We aimed to measure the expression levels of P2X7R in peripheral blood mononuclear cells (PBMCs) from patients with myasthenia gravis (MG) and to investigate whether the expression of P2X7R is associated with pathogenesis of MG.

PATIENTS AND METHODS

A total of 32 patients with MG (12 generalized MG (GMG) and 20 Ocular MG (OMG) and 22 healthy donors were recruited in this study. The quantitative MG score was used to evaluate the clinical severity. Real-time PCR and western blot were used to measure the levels of P2X7R expressed in PBMCs. Serum Th17-related cytokines (IL-1β, IL-6, IL-17 and IL-21) were tested by ELISA. PBMCs from MG patients were purified and challenged by LPS with or without a selective P2X7R inhibitor (BBG).

RESULTS

Our results showed that the expression of P2X7R mRNA and protein in PBMCs was increased in MG patients compared with healthy controls, with higher expression in generalized patients (GMG) than in ocular patients (OMG). In addition, P2X7R expression presents a significantly positive correlation with clinical severity and serum levels of IL-1β, IL-6, IL-17 and IL-21 in MG. In cultured MG PBMC, LPS challenge led to up-regulated P2X7R expression accompanied with increased production of IL-1β, IL-6, IL-17 and IL-21. Importantly, P2X7R blockade with BBG significantly attenuates the LPS-induced production of cytokines.

CONCLUSION

P2X7R expression was up-regulated in MG and LPS-P2X7R axis may be involved in the pathogenesis of MG by promoting Th17 immune response.

Feasibility of up-regulating CD4(+)CD25(+) Tregs by IFN-γ in myasthenia gravis patients

Background

In myasthenia gravis (MG) patients, the dysfunction of CD4⁺CD25⁺ regulatory T cells (CD4⁺CD25⁺ Tregs) may be one of the important pathogenesis of MG. Currently, the role of IFN-γ in autoimmune diseases is still controversial and needs further exploration. In this study, whether IFN-γ can induce CD4⁺CD25⁻ T cells into CD4⁺CD25⁺ Tregs in MG in vitro was investigated systematically.

Methods

Flow cytometry was used to analyze the number of CD4⁺CD25⁺ Tregs in MG patients and healthy controls (HCs). CD4⁺CD25⁻ T cells were separated from the peripheral blood mononuclear cells of MG patients and HCs, and the CD4⁺CD25⁺ Tregs were separated from HCs by Magnetic cell sorting (MACS). IFN-γ with different concentrations was used to stimulate CD4⁺CD25⁻ T cells. The percentages of the induced CD4⁺CD25⁺ T cells were detected by flow cytometry. The FoxP3 expression of the induced CD4⁺CD25⁺ T cells in MG patients was detected by real-time PCR at mRNA level. The induced CD4⁺CD25⁺ T cells were co-cultured with autologous CD4⁺CD25⁻ T cells to estimate the suppressive ability of the induced CD4⁺CD25⁺ T cells to CD4⁺CD25⁻ T cells.

Results

It shows the percentages of CD4⁺CD25⁺ T cells among CD4⁺ T cells have no significant difference in MG patients compared with those in HCs. There is also merely no difference in the percentages of CD4⁺CD25⁺ T cells between thymectomized and non-thymectomized MG patients. CD4⁺CD25⁻ T cells can be induced to CD4⁺CD25⁺ T cells after applying IFN-γ in MG patients and HCs. The proportion and FoxP3 expression of the induced CD4⁺CD25⁺ T cells are the highest at the level of 40 ng/ml IFN-γ, and the suppressive function of the CD4⁺CD25⁺ T cells induced by 40 ng/ml IFN-γ is the strongest in MG patients.

Conclusions

This subject will further reveal the role of IFN-γ in the pathogenesis of MG from a new perspective. It will also provide the scientific basis for the clinical targeted therapy of MG.

Decreased microRNA miR-181c expression in peripheral blood mononuclear cells correlates with elevated serum levels of IL-7 and IL-17 in patients with myasthenia gravis

miR-181c is a newly identified negative regulator of immune cell activation. In this study, we aimed to investigate the expression and functional role of miR-181c in myasthenia gravis (MG). miR-181c showed significant downregulation in peripheral blood mononuclear cells (PBMCs) from MG patients compared with healthy controls, with lower expression in generalized patients than in ocular ones. MG patients also had increased serum IL-7 and IL-17 levels. Additionally, serum IL-7 level presents a positive correlation with the serum IL-17 level. miR-181c levels were negatively correlated with serum levels of IL-7 and IL-17 in either generalized patients or ocular patients. A luciferase reporter assay revealed that miR-181c could directly bind to the 3'-UTR of interleukin-7. Forced expression of miR-181c led to decreased IL-7 and IL-17 release in cultured PBMCs, while depletion of miR-181c increased the secretion of these two proinflammatory cytokines. The results from our study suggested for the first time that miR-181c was able to negatively regulate the production of proinflammatory cytokines IL-7 and IL-17 in MG patients, and it is a novel potential therapeutic target for MG.

IL-17-producing CD4(+) T cells contribute to the loss of B-cell tolerance in experimental autoimmune myasthenia gravis

The role of Th17 cells in the pathogenesis of autoantibody-mediated diseases is unclear. Here, we assessed the contribution of Th17 cells to the pathogenesis of experimental autoimmune myasthenia gravis (EAMG), which is induced by repetitive immunizations with Torpedo californica acetylcholine receptor (tAChR). We show that a significant fraction of tAChR-specific CD4(+) T cells is producing IL-17. IL-17(ko) mice developed fewer or no EAMG symptoms, although the frequencies of tAChR-specific CD4(+) T cells secreting IL-2, IFN-γ, or IL-21, and the percentage of FoxP3(+) Treg cells were similar to WT mice. Even though the total anti-tAChR antibody levels were equal, the complement fixating IgG2b subtype was reduced in IL-17(ko) as compared to WT mice. Most importantly, pathogenic anti-murine AChR antibodies were significantly lower in IL-17(ko) mice. Furthermore, we confirmed the role of Th17 cells in EAMG pathogenesis by the reconstitution of TCR β/δ(ko) mice with WT or IL-17(ko) CD4(+) T cells. In conclusion, we show that the level of IgG2b and the loss of B-cell tolerance, which results in pathogenic anti-murine AChR-specific antibodies, are dependent on IL-17 production by CD4(+) T cells. Thus, we describe here for the first time how Th17 cells are involved in the induction of classical antibody-mediated autoimmunity.

Intrathymic Tfh/B Cells Interaction Leads to Ectopic GCs Formation and Anti-AChR Antibody Production: Central Role in Triggering MG Occurrence

Myasthenia gravis is a typical acetylcholine receptor (AChR) antibody-mediated autoimmune disease in which thymus frequently presents follicular hyperplasia or thymoma. It is now widely accepted that the thymus is probably the site of AChR autosensitization and autoantibody production. However, the exact mechanism that triggers intrathymic AChR antibody production is still unknown. T follicular helper cells, recently identified responsible for B cell maturation and antibody production in the secondary lymphoid organs, were involved in many autoimmune diseases. Newly studies found T follicular helper (Tfh) cells increased in the peripheral blood of myasthenia gravis (MG). Whether it appears in the thymus of MG and its role in the intrathymic B cells help and autoantibody production is unclear. Therefore, this study aims to determine in more detail whether Tfh/B cell interaction exist in MG thymus and to address its role in the ectopic germinal centers (GCs) formation and AChR antibody production. We observed the frequency of Tfh cells and its associated transcription factor Bcl-6, key cytokine IL-21 enhanced both in the thymocytes and peripheral blood mononuclear cells (PBMCs) of MG patients. In parallel, we also showed increased B cells and autoantibody titers in MG peripheral blood and thymus. Confocal microscope results demonstrated Tfh and B cells co-localized within the ectopic GCs in MG thymus, suggesting putative existence of Tfh/B cells interaction. In vitro studies further showed dynamic behavior of Tfh/B cells interaction and Tfh cells induced autoantibody secretion might through its effector cytokine IL-21. Altogether, our data demonstrated that intrathymic Tfh/B cells interaction played a key role in thymic ectopic GCs formation and anti-AChR antibody production, which might trigger MG occurrence.

Experimental Autoimmune Myasthenia Gravis (EAMG): from immunochemical characterization to therapeutic approaches

Myasthenia Gravis (MG) is an organ-specific autoimmune disease. In high percentage of patients there are autoantibodies to the nicotinic acetylcholine receptor (AChR) that attack AChR on muscle cells at the neuromuscular junction, resulting in muscle weakness. Experimental Autoimmune Myasthenia Gravis (EAMG) is an experimental model disease for MG. EAMG is induced in several animal species by immunization with acetylcholine receptor (AChR), usually isolated from the electric organ of electric fish, which is a rich source for this antigen. Our lab has been involved for several decades in research of AChR and of EAMG. The availability of an experimental autoimmune disease that mimics in many aspects the human disease, provides an excellent model system for elucidating the immunological nature and origin of MG, for studying various existing treatment modalities and for attempting the development of novel treatment approaches. In this review in honor of Michael Sela and Ruth Arnon, we report first on our early pioneering contributions to research on EAMG. These include the induction of EAMG in several animal species, early attempts for antigen-specific treatment for EAMG, elicitation and characterization of monoclonal antibodies and anti-idiotypic antibodies, measuring humoral and cellular AChR-specific immune responses in MG patient and more. In the second part of the review we discuss more recent studies from our lab towards developing and testing novel treatment approaches for myasthenia. These include antigen-dependent treatments aimed at specifically abrogating the humoral and cellular anti-AChR responses, as well as immunomodulatory approaches that could be used either alone, or in conjunction with antigen-specific treatments, or alternatively, serve as steroid-sparing agents.

Detection of anti-cytokine antibodies and their clinical relevance

Cytokines regulate many aspects of cell growth and differentiation and play pivotal roles in the orchestration of immune defence against invading pathogens. Though 'self' proteins, they are potentially immunogenic and can give rise to anti-cytokine autoantibodies (aCA). The main foci of the article are a critical summary of the various methodologies applied for detecting and measuring aCA and a broad review of studies of the occurrence, characterization and clinical relevance of aCA in normal healthy individuals, patients with autoimmune diseases or microbial infections and aCA in patients whose disease is treated with recombinant cytokine products. The need for technical and methodological improvement of assays, including validation and standardization, together with approaches to harmonize calculation and reporting of results is also discussed.

Functional interleukin-17 receptor A are present in the thyroid gland in intractable Graves disease

Th17 lymphocytes and its main cytokine, IL-17, play an important role in autoimmune thyroid diseases, such as intractable Graves disease (GD). IL-17 signals are transmitted through its receptor, IL-17RA. The intrathyroid expression of IL-17RA in intractable GD is not understood. In this study, ELISA was used to measure serum IL-17 levels in patients with untreated GD, intractable GD or GD in remission and healthy controls. Real-time PCR, flow cytometry and immunofluorescence staining evaluated IL-17RA mRNA and protein expression in thyrocytes. IL-6, chemokine ligand 10 (CXCL10) and intercellular adhesion molecule (ICAM)-1 expression was measured in IL-17-stimulated thyrocyte cultures to evaluate the functional status of IL-17RA. Our data indicates that serum IL-17 levels are significantly increased in intractable GD and affected thyrocytes show functional IL-17R expression. These changes facilitate the IL-17-mediated upregulation of IL-6, CXCL10, and ICAM-1. The IL-17/IL-17R interaction could be a potential target for therapeutic interventions in intractable GD.

Prophylactic effect of probiotics on the development of experimental autoimmune myasthenia gravis

Probiotics are live bacteria that confer health benefits to the host physiology. Although protective role of probiotics have been reported in diverse diseases, no information is available whether probiotics can modulate neuromuscular immune disorders. We have recently demonstrated that IRT5 probiotics, a mixture of 5 probiotics, could suppress diverse experimental disorders in mice model. In this study we further investigated whether IRT5 probiotics could modulate the progression of experimental autoimmune myasthenia gravis (EAMG). Myasthenia gravis (MG) is a T cell dependent antibody mediated autoimmune disorder in which acetylcholine receptor (AChR) at the neuromuscular junction is the major auto-antigen. Oral administration of IRT5 probiotics significantly reduced clinical symptoms of EAMG such as weight loss, body trembling and grip strength. Prophylactic effect of IRT5 probiotics on EMAG is mediated by down-regulation of effector function of AChR-reactive T cells and B cells. Administration of IRT5 probiotics decreased AChR-reactive lymphocyte proliferation, anti-AChR reactive IgG levels and inflammatory cytokine levels such as IFN-γ, TNF-α, IL-6 and IL-17. Down-regulation of inflammatory mediators in AChR-reactive lymphocytes by IRT5 probiotics is mediated by the generation of regulatory dendritic cells (rDCs) that express increased levels of IL-10, TGF-β, arginase 1 and aldh1a2. Furthermore, DCs isolated from IRT5 probiotics-fed group effectively converted CD4⁺ T cells into CD4⁺Foxp3⁺ regulatory T cells compared with control DCs. Our data suggest that IRT5 probiotics could be applicable to modulate antibody mediated autoimmune diseases including myasthenia gravis.

T helper type 17 cells expand in patients with myasthenia-associated thymoma

Myasthenia gravis (MG) is a prototypical CD4(+) T cell-dependent autoimmune disease mediated by anti-acetylcholine receptor autoantibodies (AChR-Abs). Certain subsets of helper T cells are suggested to be involved in the pathogenesis of MG, including Th1 and regulatory T cells (Treg). However, whether the recently identified Th17 cells play a role in the development of MG and its prognosis is still unknown. Here, we demonstrated that Th17 cells and their associated cytokines are increased, while the Treg cells are decreased in the peripheral blood mononuclear cells (PBMCs) from MG patients with thymomas (TM), but not from those with normal thymus (NT) or thymic hyperplasia (TH). Furthermore, the quantity of Th17 cells correlates with the quantitative myasthenia gravis (QMG) score in patients with TM. We also found a significant positive relationship between the frequency of Th17 cells (%) and the concentration of AChR antibodies in patients with MG. Therefore, the Th17/Treg imbalance in TM may suggest MG with certain pathological subtype, and the increase in Th17 cells may reveal the severity of the disease, which is valuable in the diagnosis and choice of therapeutic strategy for patients with MG.

Activation of the adenosine A2A receptor attenuates experimental autoimmune myasthenia gravis severity

The adenosine A2A receptor (A2AR) is the major cellular adenosine receptor commonly associated with immunosuppression. Here, we investigated whether A2AR activation holds the potential for impacting the severity of experimental autoimmune myasthenia gravis (EAMG) induced following immunization of Lewis rats with the acetylcholine receptor (AChR) R97-116 peptide. This report demonstrates reduced A2AR expression by both T cells and B cells residing in spleen and lymph nodes following EAMG induction. A2AR stimulation inhibited anti-AChR antibody production and proliferation of AChR-specific lymphocytes in vitro. Inhibition was blocked with the A2AR antagonists or protein kinase A inhibitor. We also determined that the development of EAMG was accompanied by a T-helper cell imbalance that could be restored following A2AR stimulation that resulted in increased Treg cell levels and a reduction in Th1-, Th2-, and Th17-cell subtypes. An EAMG-preventive treatment regimen was established that consisted of (2-(p-(2-carbonylethyl)phenylethylamino)-5-N-ethylcarboxamidoadenosine) (CGS21680; A2AR agonist) administration 1 day prior to EAMG induction. Administration of CGS21680 29 days post EAMG induction (therapeutic treatment) also ameliorated disease severity. We conclude that A2AR agonists may represent a new class of compounds that can be developed for use in the treatment of myasthenia gravis or other T-cell- and B-cell-mediated autoimmune diseases.

Complement and cytokine based therapeutic strategies in myasthenia gravis

Myasthenia gravis (MG) is a T cell-dependent and antibody-mediated disease in which the target antigen is the skeletal muscle acetylcholine receptor (AChR). In the last few decades, several immunological factors involved in MG pathogenesis have been discovered mostly by studies utilizing the experimental autoimmune myasthenia gravis (EAMG) model. Nevertheless, MG patients are still treated with non-specific global immunosuppression that is associated with severe chronic side effects. Due to the high heterogeneity of AChR epitopes and antibody responses involved in MG pathogenesis, the specific treatment of MG symptoms have to be achieved by inhibiting the complement factors and cytokines involved in anti-AChR immunity. EAMG studies have clearly shown that inhibition of the classical and common complement pathways effectively and specifically diminish the neuromuscular junction destruction induced by anti-AChR antibodies. The inborn or acquired deficiencies of IL-6, TNF-α and TNF receptor functions are associated with the lowest EAMG incidences. Th17-type immunity has recently emerged as an important contributor of EAMG pathogenesis. Overall, these results suggest that inhibition of the complement cascade and the cytokine networks alone or in combination might aid in development of future treatment models that would reduce MG symptoms with highest efficacy and lowest side effect profile.

Research advancement in immunopathogenesis of myasthenia gravis

Myasthenia gravis (MG) is an autoimmune neuromuscular junction disease mediated by antibodies against the acetylcholine receptor (AChR). The etiology and immunopathogenesis of MG remain unclear. Recent research has shown the involvement of autoantibodies, lymphocytes, cytokines and chemokines, in the pathogenesis of MG. Systematic factors are also demonstrated, such as inheritance and endocrine. This review indicates the research development in immunopathogenesis of MG.

Association of the -31C/T functional polymorphism in the interleukin-1beta gene with the intractability of Graves' disease and the proportion of T helper type 17 cells

Interleukin (IL)-1beta is a proinflammatory cytokine and has been implicated in the pathogenesis of several autoimmune diseases. To evaluate the hypothesis that the functional -31C/T polymorphism (rs1143627) in the gene encoding IL-1beta is associated with the intractability and the severity of autoimmune thyroid diseases, we genotyped this polymorphism in 64 patients with intractable Graves' disease (GD), 28 GD patients in remission, 49 patients with Hashimoto's disease (HD) who developed hypothyroidism (severe HD), 28 untreated euthyroid HD patients (mild HD) and 59 healthy volunteers. The -31T allele, which is related to the high producibility of IL-1beta, was significantly more frequent in patients with intractable GD than in those with GD in remission (P = 0.0017; odds ratio 2.8; 95% confidence interval 1.5-5.3), although there was no difference in this frequency between two groups of HD patients. We showed additionally that the proportion of IL-17-producing T helper type 17 (Th17) cells, whose differentiation and proliferation are promoted by IL-1beta, was higher in autoimmune thyroid disease patients with the T allele than in those with CC genotypes. In conclusion, our data indicated that the T allele of -31C/T polymorphism in the IL1B gene was involved in the intractability of GD, and this involvement may arise through the differentiation and proliferation of Th17 cells.

Suppression of ongoing experimental autoimmune myasthenia gravis by transfer of RelB-silenced bone marrow dentritic cells is associated with a change from a T helper Th17/Th1 to a Th2 and FoxP3+ regulatory T-cell profile

OBJECTIVE

To observe the therapeutic effect of RelB-silenced dendritic cells (DCs) in experimental autoimmune myasthenia gravis (EAMG), and further to investigate the mechanism of this immune system therapeutic.

METHODS

(1) RelB-silenced DCs and control DCs were prepared and the supernatants were collected for IL-12p70, IL-6, and IL-23 measurement by ELISA. (2) RelB-silenced DCs and control DCs were co-cultured with AChR-specific T cells, and the supernatant was collected to observe the IL-17, IFN-gamma, IL-4 production. (3) EAMG mice with clinical scores of 1 to 2 were collected and enrolled randomly into the RelB-silenced DC group or the control DC group. RelB-silenced DCs or an equal amount of control DCs were injected intravenously on days 0, 7, and 14 after enrollment. Clinical scores were evaluated every other day. Twenty days after allotment, serum from individual mice was collected to detect serum concentrations of anti-mouse AChR IgG, IgG1, IgG2b, and IgG2c. The splenocytes were isolated for analysis of lymphocyte proliferative responses, cytokine (IL-17, IFN-gamma, IL-4) production, and protein levels of RORgammat, T-bet, GATA-3, and FoxP3 (the special transcription factors of Th17, Th1, Th2, and Treg, respectively).

RESULTS

(1) RelB-silenced DCs produced significantly reduced amounts of IL-12p70, IL-6, and IL-23, as compared with control DCs. (2) RelB-silenced DCs spurred on the CD4(+) T cells from Th1/Th17 to the Th2 cell subset in the co-culture system. (3) Treatment with RelB-silenced DCs effectively reduced myasthenic symptoms and levels of serum anti-acetylcholine receptor autoantibody in mice with ongoing EAMG. Th17-related markers (RORgammat, IL-17) and Th1-related markers (T-bet, IFN-gamma) were downregulated, whereas Th2 markers (IL-4 and GATA3) and Treg marker (FoxP3) were upregulated.

CONCLUSIONS

RelB-silenced DCs were able to create a particular cytokine environment that was absent of inflammatory cytokines. RelB-silenced DCs provide a practical means to normalize the differentiation of the four T-cell subsets (Th17, Th1, Th2, and Treg) in vivo, and thus possess therapeutic potential in Th1/Th17-dominant autoimmune disorders such as myasthenia gravis.

Towards retinoid therapy for Alzheimer's disease

Alzheimer's disease(AD) is associated with a variety of pathophysiological features, including amyloid plaques, inflammation, immunological changes, cell death and regeneration processes, altered neurotransmission, and age-related changes. Retinoic acid receptors (RARs) and retinoids are relevant to all of these. Here we review the pathology, pharmacology, and biochemistry of AD in relation to RARs and retinoids, and we suggest that retinoids are candidate drugs for treatment of AD.

Increases of the Th1/Th2 cell ratio in severe Hashimoto's disease and in the proportion of Th17 cells in intractable Graves' disease

BACKGROUND

T helper type 1 (Th1), Th2, and Th17 cells produce interferon (IFN)-gamma, interleukin (IL)-4, and IL-17A, respectively. We reported that IFN-gamma and IL-4 gene polymorphisms, which are related to higher IFN-gamma and lower IL-4 production, respectively, are more frequent in patients with severe Hashimoto's disease (HD) than in those mild HD. We now aim to investigate the proportion of peripheral Th1, Th2, and Th17 cells in patients with autoimmune thyroid disease (AITD).

METHODS

We studied 17 patients with HD who developed hypothyroidism and were treated with l-thyroxine, referred to as severe HD; 17 untreated patients with HD who were euthyroid, referred to as mild HD; 18 euthyroid patients with Graves' disease (GD) who remained positive for anti-thyrotropin receptor antibody (TRAb) despite being treated with anti-thyroid drugs for more than 5 years, referred to as intractable GD; and 17 patients with GD who were euthyroid and negative for TRAb for more than 2 years after cessation of anti-thyroid drugs, referred to as GD in remission; and 10 control subjects without AITD. By the definitions in this study Th1 cells were CD4(+)IFN-gamma(+)IL-4(-)IL-17A(-) cells, Th2 cells were CD4(+)IFN-gamma(-)IL-4(+)IL-17A(-) cells, and CD4(+)IFN-gamma(-)IL-4(-)IL-17A(+) cells were Th17 cells.

RESULTS

The proportion of peripheral Th1 cells was higher in patients with severe HD than in patients with mild HD (p < 0.05), and the proportion of peripheral Th2 cells was lower in patients with severe HD than in patients with mild HD (p < 0.001). Therefore the Th1/Th2 ratio was higher in severe than in mild HD patients (p < 0.001). The proportion of peripheral Th17 cells in patients with AITD was higher than in control subjects and the proportion of these cells in patients with intractable GD was higher than in patients with GD in remission (p < 0.05).

CONCLUSIONS

The peripheral Th1/Th2 cell ratio is related to the severity of HD, and the proportion of Th17 cells is related to the intractability of GD. We hypothesize that these patterns of peripheral Th cell subsets may be expressed within the thyroid.

BM stromal cells ameliorate experimental autoimmune myasthenia gravis by altering the balance of Th cells through the secretion of IDO

In addition to their capacity to differentiate, BM stromal cells (BMSC) have immunosuppressive qualities that make them strong candidates for use in cell therapy against human autoimmune diseases. We studied the immunoregulatory activities of BMSC on experimental autoimmune myasthenia gravis (EAMG) in vitro and in vivo. Intravenous administration of syngenic BMSC to EAMG-model rats on the day of their second immunization was effective in ameliorating the pathological features of the disease. In vitro, the proliferative ability of T cells or B cells from EAMG rats was inhibited when they were cocultured with BMSC at proper ratios. This inhibitory effect was at least partially dependent on the secretion of IDO. We also determined that the development of EAMG is accompanied by an imbalance among the Th1, Th2, Th17, and Treg cell subsets, and that this can be corrected by the administration of BMSC, which leads to an increase of Th2 (IL-4) and Treg (Foxp3) cells, and a reduction of Th1 (IFN-gamma) and Th17 (IL-17) cells, through an IDO-dependent mechanism. These results provide further insights into the pathogenesis of MG, EAMG, and other immune-mediated diseases, and support a potential role for BMSC in their treatment.

Disequilibrium of T helper type 1, 2 and 17 cells and regulatory T cells during the development of experimental autoimmune myasthenia gravis

Experimental autoimmune myasthenia gravis (EAMG), an animal model of myasthenia gravis (MG), is a rare organ-specific autoimmune disease targeting the autoantigen nicotinic acetylcholine receptor (AChR). We show here that the balance of T helper type 1 (Th1), Th2, Th17 and regulatory T (Treg) subsets of CD4(+) helper T cells were redistributed during the development of EAMG and that the interleukin-17 (IL-17) cytokine is involved in this disease. The ratio of Th17 cells changed most notably with disease progression accompanied by an up-regulated level of IL-17. Moreover, the proliferative ability of AChR peptide-specific T cells and the anti-AChR antibody-secreting cells increased when stimulated by IL-17 in vitro. These findings suggested that the disequilibrium of the CD4(+) helper T-cell subsets could promote the development of EAMG, and the pathogenic mechanism by which Th17 cells drives autoimmune responses by secreting cytokine IL-17 provides a new target for myasthenia gravis therapy.

Administration of bone marrow stromal cells ameliorates experimental autoimmune myasthenia gravis by altering the balance of Th1/Th2/Th17/Treg cell subsets through the secretion of TGF-beta

Bone marrow stromal cells (BMSCs) are strong candidates for cell therapy against human autoimmune diseases. Intravenous administration of syngenic BMSCs to EAMG-model rats effectively ameliorated the disease, partially through a TGF-beta-dependent mechanism. The proliferative ability of T or B cells from EAMG rats was inhibited by BMSCs at proper cocultured ratios. And the imbalance of Th1, Th2, Th17 and Treg cell subsets accompanied with the development of EAMG was corrected by the administration of BMSCs. These results provide further insights into the pathogenesis of MG, EAMG, and other immune-mediated diseases, and support a potential role for BMSCs in their treatment.

Ex vivo generated regulatory T cells modulate experimental autoimmune myasthenia gravis

Naturally occurring CD4(+)CD25(+) regulatory T (Treg) cells are key players in immune tolerance and have therefore been suggested as potential therapeutic tools for autoimmune diseases. In myasthenia gravis (MG), reduced numbers or functionally impaired Treg cells have been reported. We have observed that PBL from myasthenic rats contain decreased numbers of CD4(+)CD25(high)Foxp3(+) cells as compared with PBL from healthy controls, and we have tested whether Treg cells from healthy donors can suppress experimental autoimmune MG in rats. Because the number of naturally occurring Treg cells is low, we used an approach for a large-scale ex vivo generation of functional Treg cells from CD4(+) splenocytes of healthy donor rats. Treg cells were generated ex vivo from CD4(+) cells by stimulation with anti-CD3 and anti-CD28 Abs in the presence of TGF-beta and IL-2. The obtained cells expressed high levels of CD25, CTLA-4, and Foxp3, and they were capable of suppressing in vitro proliferation of T cells from myasthenic rats in response to acetylcholine receptor, the major autoantigen in myasthenia. Administration of ex vivo-generated Treg cells to myasthenic rats inhibited the progression of experimental autoimmune MG and led to down-regulation of humoral acetylcholine receptor-specific responses, and to decreased IL-18 and IL-10 expression. The number of CD4(+)CD25(+) cells in the spleen of treated rats remained unchanged, but the subpopulation of CD4(+)CD25(+) cells expressing Foxp3 was significantly elevated. Our findings imply that Treg cells play a critical role in the control of myasthenia and could thus be considered as potential agents for the treatment of MG patients.

Interleukin-23 restrains regulatory T cell activity to drive T cell-dependent colitis

Interleukin-23 (IL-23) is an inflammatory cytokine that plays a key role in the pathogenesis of several autoimmune and inflammatory diseases. It orchestrates innate and T cell-mediated inflammatory pathways and can promote T helper 17 (Th17) cell responses. Utilizing a T cell transfer model, we showed that IL-23-dependent colitis did not require IL-17 secretion by T cells. Furthermore, IL-23-independent intestinal inflammation could develop if immunosuppressive pathways were reduced. The frequency of naive T cell-derived Foxp3+ cells in the colon increased in the absence of IL-23, indicating a role for IL-23 in controlling regulatory T cell induction. Foxp3-deficient T cells induced colitis when transferred into recipients lacking IL-23p19, showing that IL-23 was not essential for intestinal inflammation in the absence of Foxp3. Taken together, our data indicate that overriding immunosuppressive pathways is an important function of IL-23 in the intestine and could influence not only Th17 cell activity but also other types of immune responses.