CD4+T Cells and Cytokines in the Pathogenesis of Acquired Myasthenia Gravis

Increased serum interleukin-41 correlates with disease severity in myasthenia gravis

BACKGROUND

Myasthenia gravis (MG) is an autoimmune disease mediated by pathogenic antibodies produced by abnormally activated B cells, resulting in neuromuscular junction transmission dysfunction. Interleukin-41 (IL-41) is a novel immunomodulatory cytokine that has been implicated in various metabolic, inflammatory, and autoimmune diseases. The role of IL-41 in MG is still unclear up to now, our study aimed to investigate the level of IL-41 in MG patients and its correlation with clinical features and inflammatory indicators.

METHODS

Totally, 60 MG patients and 30 healthy controls (HC) were recruited. Baseline data and laboratory parameters were routinely recorded through electronic medical systems. IL-41 levels were measured by enzyme-linked immunosorbent assay. Proportions of T-cell and B-cell subsets and natural killer cells were analyzed by flow cytometry. The correlation between serum IL-41 and MG related parameters was investigated, and the clinical value of IL-41 in the diagnosis of MG was evaluated by receiver operator characteristic curve (ROC) analysis.

RESULTS

Serum IL-41 levels in MG patients were higher than in HC, and were higher in Myasthenia Gravis Foundation of America (MGFA) III + IV group than that in MGFA I + II group. Serum IL-41 was positively correlated with MG-specific activities of daily living scale (MG-ADL), MGFA classification, platelet to lymphocyte ratio (PLR), and proportion of CD19+ B cells, while it was negatively correlated with high-sensitive C-reactive protein (hs-CRP) and circulatory plasma cells in MG patients. Serum IL-41 levels increased in patients who were treated with efgartigimod during the first cycle of therapy. However, compared to disease initiation, serum IL-41 levels decreased when clinical features steadily improved. ROC analysis showed that IL-41 had a diagnostic value for MG.

CONCLUSION

The present findings suggested that serum IL-41 was increased in MG patients and was positively associated with the severity of the disease. IL-41 may be essential to the immunopathological mechanism of MG and a potential biomarker for MG.

Expression of lymphocyte activation gene-3 on CD4+T cells is regulated by cytokine interleukin-18 in myasthenia gravis

Myasthenia gravis (MG) is a T cell-dependent, B cell-mediated, and complement-dependent autoimmune disease. Lymphocyte activation gene-3 (LAG-3; CD223) is an immune checkpoint protein that plays an important role in maintaining autoimmune tolerance and homeostasis. To investigate the cytokine-regulated expression pattern of LAG-3, CD4+T cells were sorted from the peripheral blood of healthy volunteers by density gradient centrifugation and stimulated with various cytokines in vitro. The expression of membrane LAG-3 (mLAG-3), membrane a disintegrin and metallopeptidase domain10 (mADAM10) and membrane ADAM17 (mADAM17) on CD4+T cells was detected by flow cytometry; the concentration of soluble LAG-3 (sLAG-3) was detected by ELISA; and the relative expression of genes at the transcriptional level was detected by fluorescence quantitative RT-PCR (qRT-PCR). sLAG-3 levels were significantly increased in the peripheral plasma of AChR Ab-positive patients with MG compared to healthy volunteers, while the percentage of mLAG-3 expression on CD4+T lymphocytes in the peripheral blood of patients with MG was significantly reduced. IL-18 inhibited mLAG-3 levels on CD4+T cells in a concentration-dependent manner. Additionally, the concentration of sLAG-3 in the supernatant increased. After PHA and IL-18 stimulation, ADAM10 and ADAM17 also increased compared to those in the PHA-active group. Moreover, there were significant differences in the expression of mADAM10 and mADAM17 in CD4+T lymphocytes between patients with MG and healthy volunteers. These results suggest that IL-18 may regulate the expression pattern of mLAG-3 in CD4+T cells and sLAG-3 via ADAM10- and ADAM17-mediated pathways, thus affecting the immune effects of CD4+T cells. This study provides a preliminary exploration of the upstream regulatory molecules of the LAG-3 and IL-18/LAG-3 signalling pathways for potential targeted therapy of autoimmune diseases in the future.

Altered serum levels of cytokines in patients with myasthenia gravis

Background

Myasthenia gravis (MG) is an autoimmune disease characterized by generalized skeletal muscle contraction weakness due to autoantibodies targeting neural-muscular junctions. Here, we investigated the relationship between key cytokines and MG type, disease course, antibodies, and comorbidities.

Method

Cytokine levels in serum samples collected from MG (n = 45) and healthy control (HC, n = 38) patients from January 2020 to June 2022 were quantified via flow cytometry.

Results

Levels of IL-6 were higher in the MG group versus healthy individuals (p = 0.026) and in patients with generalized versus ocular MG (p = 0.019). IL-6 levels were positively correlated with QMG score. In patients with MG with both AChR and Titin antibodies, serum levels of sFas and granulysin were higher than in those with AChR alone (p = 0.036, and p = 0.028, respectively). LOMG had a reduction in serum levels of IL-2 compared to EOMG (p = 0.036). LOMG patients with diabetes had lower serum levels of IL-2, IL-4, and IFN-γ (p = 0.044, p = 0.038, and p = 0.047, respectively) versus those without diabetes. sFas in the MG with Abnormal thymus were reduced compared to those in MG with Normal thymus (p = 0.008).

Conclusions

This study revealed a positive correlation between IL-6 level and MG status. Serum cytokine levels of the AChR + Titin MG group differed from those of the AChR group. LOMG had a lower IL-2 level. Comorbidities affect some cytokines in peripheral blood in MG serum.

Therapeutic effect of ofatumumab in patients with myasthenia gravis: immunoregulation of follicular T helper cells and T helper type 17 cells

Introduction

This study aimed to study the therapeutic effects of ofatumumab in patients with myasthenia gravis (MG) in addition to the immunomodulatory effects on peripheral follicular T helper (Tfh) cells and T helper type 17 (Th17) cells.

Methods

Thirty-one patients with anti-acetylcholine receptor (AChR) antibody-positive MG were included in this study. At weeks 0, 1, 2, and 4, an initial dose of 20 mg of ofatumumab was injected subcutaneously, with a 2-month follow-up after completing this first cycle. At baseline, 1 month, and 3 months, we assessed the Quantitative MG (QMG), 15-item MG-Quality of Life (MG-QOL15), and MG-Activities of Daily Living (MG-ADL) scales and measured the frequencies of Tfh, Th17, and B cells and the levels of anti-AChR antibody, IL-6, IL-21, and IL-17 in the peripheral blood.

Results

At 1 month and 3 months, the QMG, MG-QOL15, and MG-ADL scores were all significantly reduced. At 3 months, doses of prednisone were reduced by an average of 37%. Decreased frequencies of Tfh and Th17 cells, depletion of B cells, and reduced levels of IL-6, IL-21, and IL-17 were all observed at 1 month or 3 months.

Discussion

Therefore, the therapeutic effect of ofatumumab could be detected after one cycle of treatment, which was maintained for 2 months. The immunomodulatory effect of ofatumumab during the observation period may involve depletion of B cells, reduction of Tfh and Th17 cells frequencies, and reduced levels of IL-6, IL-21, and IL-17. The findings provide novel data for the potential application of ofatumumab in MG.

Sodium butyrate alleviates R97-116 peptide-induced myasthenia gravis in mice by improving the gut microbiota and modulating immune response

Fermented butyrate exhibits an anti-inflammatory response to maintain immune homeostasis within the gut. However, the effect and underlying mechanism of butyrate on myasthenia gravis (MG) remain unclear. The changes in the gut microbiota and fecal contents of SCFAs in MG patients were examined. R97-116 peptide was used to induce the experimental autoimmune myasthenia gravis (EAMG) mice and sodium butyrate (NaB) was gavaged to the EAMG mice. Gut microbiota, the frequency of Th1, Th17, Treg, Tfh, and B cells, the levels of IFN-γ, IL-17 A, IL-10, IL-21, and anti-R97-116 IgG, RNA-seq of total B cells in the spleen were explored by metagenomics, flow cytometry, ELISA, and transcriptomics. A significant reduction in SCFA-producing bacteria including Butyricimonas synergistica and functional modules including butyrate synthesis/production II was observed in MG patients and fecal SCFAs detection confirmed the increase. The EAMG mice were successfully constructed and NaB supplementation has changed the composition and function of the gut microbiota. The numbers of Th1, Th17, Tfh, and B cells were significantly increased while that of Treg cells was obviously decreased in EAMG mice compared with controls. Interestingly, NaB treatment has reduced the amounts of Th17, Tfh, and B cells but increased that of Treg cells. Accordingly, the levels of IL-17 A, IL-21, and IgG were increased while IL-10 was decreased in EAMG mice. However, NaB treatment reduced IL-17 A and IL-21 but increased that of IL-10. RNA-seq of B cells has revealed 4577 deferentially expressed genes (DEGs), in which 1218 DEGs were up-regulated while 3359 DEGs were down-regulated in NaB-treated EAMG mice. GO enrichment and KEGG pathway analysis unveiled that the function of these DEGs was mainly focused on immunoglobulin production, mitochondrial respiratory chain complex, ribosome, oxidative phosphorylation, and CNS diseases including amyotrophic lateral sclerosis. We have found that butyrate was significantly reduced in MG patients and NaB gavage could evidently improve MG symptoms in EAMG mice by changing the gut microbiota, regulating the immune response, and altering the gene expression and function of B cells, suggesting NaB might be a potential immunomodulatory supplement for MG drugs.

Astragaloside IV ameliorates experimental autoimmune myasthenia gravis by regulating CD4 + T cells and altering gut microbiota

BACKGROUND

Myasthenia gravis (MG) is an antibody-mediated autoimmune disease and its pathogenesis is closely related to CD4 + T cells. In recent years, gut microbiota is considered to play an important role in the pathogenesis of MG. Astragaloside IV (AS-IV) is one of the main active components extracted from Astragalus membranaceus and has immunomodulatory effects. To study the immunomodulatory effect of AS-IV and the changes of gut microbiota on experimental autoimmune myasthenia gravis (EAMG) mice, we explore the possible mechanism of AS-IV in improving MG.

METHODS

In this study, network pharmacology was utilized to screen the crucial targets of AS-IV in the treatment of MG. Subsequently, a Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was performed to identify potential pathways through which AS-IV acts against MG. Furthermore, experimental investigations were conducted to validate the underlying mechanism of AS-IV in MG treatment. Before modeling, 5 mice were randomly selected as the control group (CFA group), and the other 10 were induced to EAMG model. These mice were randomly divided into EAMG group and EAMG + AS-IV group, n = 5/group. In EAMG + AS-IV group, AS-IV was administered by gavage. CFA and EAMG groups were given the same volume of PBS. Body weight, grip strength and clinical symptoms were assessed and recorded weekly. At the last administration, the feces were collected for 16S RNA microbiota analysis. The levels of Treg, Th1 and Th17 cells in spleen and Th1 and Th17 cells in thymus were detected by flow cytometry. The levels of IFN-γ, IL-17 and TGF-β in serum were measured by ELISA. Furthermore, fecal microbial transplantation (FMT) experiments were performed for exploring the influence of changed intestinal flora on EAMG. After EAMG model was induced, the mice were treated with antibiotics daily for 4 weeks to germ-free. Then germ-free EAMG mice were randomly divided into two groups: FMT EAMG group, FMT AS-IV group, n = 3/group. Fecal extractions from EAMG and EAMG + AS-IV groups as gathered above were used to administered daily to the respective groups for 4 weeks. Body weight, grip strength and clinical symptoms were assessed and recorded weekly. The levels of Treg, Th1 and Th17 cells in spleen and Th1 and Th17 cells in thymus were detected at the last administration. The levels of IFN-γ, IL-17 and TGF-β in serum were measured by ELISA.

RESULTS

The network pharmacology and KEGG pathway analysis revealed that AS-IV regulates T cell pathways, including T cell receptor signaling pathway and Th17 cell differentiation, suggesting its potential in improving MG. Further experimental verification demonstrated that AS-IV administration improved muscle strength and body weight, reduced the level of Th1 and Th17 cells, enhanced the level of Treg cells, and resulted in alterations of the gut microbiota, including changes in beta diversity, the Firmicutes/Bacteroidetes (F/B) ratio, and the abundance of Clostridia in EAMG mice. We further conducted FMT tests and demonstrated that the EAMG Abx-treated mice which were transplanted the feces of mice treated with AS-IV significantly alleviated myasthenia symptoms, reduced Th1 and Th17 cells levels, and increased Treg cell levels.

CONCLUSION

This study speculated that AS-IV ameliorates EAMG by regulating CD4 + T cells and altering the structure and species of gut microbiota of EAMG.

Increased Expression of CD95 in CD4+ Effector Memory T Cells Promotes Th17 Response in Patients with Myasthenia Gravis

Emerging data have revealed that CD95 can evoke non-apoptotic signals, thereby promoting pro-inflammatory functions that link to the severity of autoimmune disorders. Here, we reported that the expression of CD95 in CD4⁺ effector memory T (CD4⁺ TEM) cells was increased in myasthenia gravis (MG) patients. We also found increased expression of CD95 in CD4⁺ TEM cells from MG patients correlated positively with clinical severity scores (QMGs), serum IL-17 levels and plasma cells (PCs) frequencies. Conventional treatment, such as glucocorticoid, could down-regulate the expression of CD95 in CD4⁺ TEM cells, QMGs, serum IL-17 levels and PCs frequencies from MG patients. In vitro, low-dose of agonistic anti-CD95 mAb could promote Th17 cell development. This effect was reversed by CD95 siRNA. Moverover, CD95 stimulation induced the phosphorylation of p38 and Erk1/2 and Th17 cell differentiation, and p38 specific inhibitor SB203580 or Erk1/2 specific inhibitor PD98059 could induce opposite changes. However, SB203580 or PD98059 do not abrogate the increase of CCR6⁺IL-17A⁺ cells, ROR-γt and IL-17 expression induced by CD95 triggering relatively to each corresponding control. This suggests that p38 and Erk1/2 MAPK pathway plays a role in expression of CCR6⁺IL-17A⁺ cells, ROR-γt and IL-17, but not in their increase induced by CD95 triggering. Taken together, this study revealed that increased expression of CD95 in CD4⁺ TEM cells promotes Th17 response under the microenvironment of MG.

LncRNA LINC00680 Acts as a Competing Endogenous RNA and Is Associated With the Severity of Myasthennia Gravis

Background and Purpose

Myasthenia gravis (MG) is a T cell-dependent antibody-mediated autoimmune disorder that can seriously affect patients' quality of life. However, few studies have focused on the severity of MG. Moreover, existing therapeutic efforts, including those targeting biomarkers for MG, remain unsatisfactory. Therefore, it is vital that we investigate the pathogenesis of MG and identify new biomarkers that can not only evaluate the severity of the disease but also serve as potential therapeutic targets. Long noncoding RNA LINC00680 has been found to be associated with the progression of a variety of diseases as a competing endogenous RNA (ceRNA). However, the specific role of LINC00680 in MG has yet to be clarified. Here, we aimed to investigate the association between LINC00680 and the severity of MG.

Methods

Bioinformatics tools, quantitative real-time PCR, Western blotting, and luciferase assays were selected to investigate key signaling pathways and RNA expression in patients with MG. The Quantitative MG Score scale and the MG Composite scale were used to evaluate the severity of MG in the included patients. Cell viability assays and flow cytometry analysis were selected to analyze cell proliferation and apoptosis.

Results

Compared with control subjects, the expression levels of LINC00680 and mitogen-activated protein kinase 1 (MAPK1) in peripheral blood mononuclear cells of patients with MG were both upregulated; the levels of miR-320a were downregulated. A positive correlation was detected between LINC00680 expression and the severity of MG. Luciferase reporter assays identified that LINC00680 acts as a target for miR-320a. The in vitro analysis confirmed that LINC00680 regulates the expression of MAPK1 by sponging miR-320a. Finally, the functional analysis indicated that LINC00680 promoted Jurkat cell proliferation and inhibited cellular apoptosis by sponging miR-320a.

Conclusion

LINC00680 may be associated with the severity of MG as a ceRNA by sponging miR-320a to upregulate MAPK1. These findings suggest that LINC00680 may represent a potential biomarker which evaluates the severity of MG and may serve as a therapeutic target.

Berberine attenuates experimental autoimmune myasthenia gravis via rebalancing the T cell subsets

Myasthenia Gravis (MG) is a T cell-driven, autoantibody-mediated disease. Here we show that oral Berberine (BBR) ameliorated clinical symptoms of experimental autoimmune myasthenia gravis(EAMG) rat model via decreasing the frequencies of Th1, Th17, Th1/17 cell subsets. JAK-STAT pathway was highlighted by transcriptomic analysis with EAMG mononuclear cells (MNCs). Surface plasmon resonance identified ligand binding interaction between BBR and JAK2, and electrostatic interaction was proposed by molecular dynamic simulation. Reduced phosphorylated JAK1/2/3 and STAT1/3 in MNCs from BBR-fed EAMG rats were demonstrated. These results suggest that BBR might improve EAMG by rebalancing T cell subsets through targeting JAK-STAT pathway.

Leflunomide ameliorates experimental autoimmune myasthenia gravis by regulating humoral and cellular immune responses

Leflunomide, an immunosuppressive disease-modifying anti-rheumatic drug (DMARD), is widely used in the treatment of rheumatoid arthritis (RA), psoriatic arthritis (PA) as well as multiple sclerosis. However, its role in myasthenia gravis (MG) has not yet been clearly explored. Here, we investigated the effect of leflunomide on experimental autoimmune myasthenia gravis (EAMG) in vivo and in vitro. The results demonstrated that leflunomide alleviated the severity of EAMG associated with reduced serum total anti-acetylcholine receptor (AChR) IgG levels. During the development of EAMG, the increase of follicular helper T cells (Tfh) 1, Tfh 17 cells and decrease of follicular regulatory T cells (Tfr) were reversely altered after leflunomide administration. Our work further found that leflunomide might inhibit Tfh cells through the IL-21/STAT3 pathway to reduce the secretion of antibodies by B cells. In addition, leflunomide rebuilt the balance of Th1/Th2/Th17/Treg subsets. These results suggested that leflunomide ameliorated EAMG severity by regulating humoral immune responses and Th cell profiles thereby providing a novel effective treatment strategy for MG.

Melatonin exerts immunoregulatory effects by balancing peripheral effector and regulatory T helper cells in myasthenia gravis

Myasthenia gravis (MG) is a prototypic organ-specific autoimmune disorder that, in most cases, is mainly mediated by antibodies against the acetylcholine receptor. Evidence implicates CD4⁺ T helper (Th) cells in the development of MG, whereas regulatory T cells (Tregs) are associated with disease resolution. Melatonin has important immunoregulatory effects in many T cell-mediated autoimmune diseases. However, there are few studies on the role of melatonin in MG. In the present study, we investigated serum melatonin levels and melatonin receptor expression in MG patients and healthy controls (HCs). We also evaluated the impact of melatonin administration on peripheral CD4⁺ Th cells and related cytokine production. Serum melatonin levels were lower in MG patients than in HCs, and MT1 expression was lower in PBMCs from MG patients than in those from HCs. Administration of melatonin significantly decreased Th1 and Th17 cell responses and proinflammatory cytokine production. Further investigation in vitro revealed that melatonin administration increased FoxP3 and IL-10 expression in CD4⁺ T cells from MG patients and enhanced the suppressive function of Tregs. These findings indicate that melatonin exerts immunoregulatory activity in MG by balancing effector and regulatory Th cell populations as well as by suppressing proinflammatory cytokine production.

The Expression Pattern and Regulatory Mechanism of the G0/G1 Switch Gene 2 (G0S2) in the Pathogenesis and Treatment of AChR Myasthenia Gravis (MG)

This study is aimed at exploring the expression pattern and methylation level of G0S2 in the peripheral blood mononuclear cells (PBMCs) of myasthenia gravis (MG) patients with positive acetylcholine receptor (AChR) autoantibodies and revealing the relationship between the G0S2 methylation pattern and MG. The relationship between the NFAT family members and G0S2 was explored to reveal the regulatory mechanism of G0S2 in the pathogenesis and treatment of AChR MG. Moreover, we attempted to demonstrate the potential therapeutic mechanism of tacrolimus in AChR MG. The relative G0S2 expression level in the PBMCs of healthy people was compared with that in the PBMCs of AChR MG patients with quantitative real-time PCR (qRT-PCR). The methylation frequency of the G0S2 promoter was detected by bisulfite sequencing PCR (BSP) and pyrosequencing. A dual-luciferase reporter system was used to reveal the relationship between the G0S2 promoter and nuclear factor of activated T cells 5 (NFAT5). The qRT-PCR results showed that G0S2 expression was significantly upregulated in the B cells and CD8+ T cells of AChR MG patients but not in the CD4+ T cells, and these expression differences were significantly associated with a decrease in G0S2 methylation. NFAT5, which was speculated to bind to island 1 (p1) in the G0S2 promoter, may regulate the lymphocyte balance by regulating G0S2 gene expression but failed to affect the methylation of the G0S2 promoter. Tacrolimus therapy-induced methylation and overexpression of NFAT5 could significantly reduce the expression of G0S2 in AChR MG patients. The G0S2 gene was remarkably upregulated in the PBMCs of MG patients. NFAT5 may affect transcription initiation and downregulate G0S2 expression through p1 in the promoter, thus controlling G0S2 gene expression and regulating the lymphocyte balance. Therefore, G0S2 could be an immune regulatory factor in both AChR MG occurrence and treatment with tacrolimus.

Statins in Neuro-ophthalmology

Statins are effective and well-tolerated hypolipidaemic agents which have been increasingly studied for their pleiotropic immunomodulatory and anti-inflammatory effects. Statins have potential therapeutic benefit in a range of neuro-ophthalmological conditions but may also induce or exacerbate certain neurological disorders. This literature review examines evidence from clinical and in vitro studies assessing the effects of statins in myasthenia gravis, myopathy, multiple sclerosis, neuromyelitis optica, idiopathic intracranial hypertension (pseudotumour cerebri), migraine, giant cell arteritis, Bell's palsy, ocular ischaemia, stroke, Alzheimer's disease and Parkinson's disease.

Unbalanced expression of membrane-bound and soluble inducible costimulator and programmed cell death 1 in patients with myasthenia gravis

This study aimed to investigate the possible functions and mechanisms of positive and negative costimulatory molecules in the pathological process of myasthenia gravis (MG). The expression levels of membrane-bound inducible costimulator (ICOS) and programmed cell death 1 (PD-1) in peripheral blood T cells, their corresponding ligands ICOSL and PDL-1 on B cells, and their soluble forms (sICOS, sPD-1, sICOSL, and sPDL-1) in plasma were detected in patients with untreated-stage MG (USMG) and remission-stage MG (RSMG). The results showed that the expression levels of membrane-bound ICOS and PD-1 in the peripheral blood T cells of the USMG group and their corresponding ligands ICOSL and PD-L1 on B cells were significantly increased compared to those in the RSMG group and healthy controls (HCs). The levels of sICOSL and sPD-1 were significantly upregulated in USMG patients compared to those in the RSMG and HC groups, while the levels of sICOS and sPD-L1 were not different. The expression of PD-L1 on CD19⁺ B cells was positively correlated with the concentrations of AchR Ab in the USMG group. The expression of ICOS and PD-1 in CD4⁺ T cells and the expression of ICOSL and PD-L1 on CD19⁺ B cells were positively correlated with the quantitative myasthenia gravis (QMG) scores in the USMG group. Also, in the USMG group, the plasma levels of sICOSL and sPD-1 were positively correlated with the QMG scores. In addition, the percentage of peripheral blood follicular helper T (Tfh) cells in the USMG group was positively correlated with ICOS and PD-1 expression on CD4⁺ T cells and ICOSL and PD-L1 expression on CD19⁺ B cells. There were positive correlations between sICOSL and sPD-1 levels and the percentage of peripheral blood Tfh cells and plasma interleukin-21 (IL-21) levels in the USMG group. The results suggest that the positive ICOS/ICOSL and negative PD-1/PD-L1 costimulatory molecule pairs participate in the pathological process of MG. Abnormal sICOSL and sPD-1 expression might interfere with the normal signal transduction of ICOS and PD-1 on Tfh cells, causing excessive activation of Tfh cells and promotion of disease progression. sICOSL and sPD-1 have potential value in monitoring MG disease states.

Inhibition of ROCK activity regulates the balance of Th1, Th17 and Treg cells in myasthenia gravis

Aberrant ROCK activation has been found in patients with several autoimmune diseases, but the role of ROCK in myasthenia gravis (MG) has not yet been clearly investigated. Here, we demonstrated that ROCK activity was significantly higher in peripheral blood mononuclear cells (PBMCs) from MG patients. ROCK inhibitor Fasudil down-regulated the proportions of Th1 and Th17 cells in PBMCs of MG patients in vitro. Intraperitoneal injection of Fasudil ameliorated the severity of experimental autoimmune myasthenia gravis (EAMG) rats and restored the balance of Th1/Th2/Th17/Treg subsets. Furthermore, Fasudil inhibited the proliferation of antigen-specific Th1 and Th17 cells, and inhibited CD4 + T cells differentiated into Th1 and Th17 through decreasing phosphorylated Stat1 and Stat3, but promoted Treg cell differentiation through increasing phosphorylated Stat5. We conclude that dysregulated ROCK activity may be involved in the pathogenic immune response of MG and inhibition of ROCK activity might serve as a novel treatment strategy for MG.

Tacrolimus inhibits Th1 and Th17 responses in MuSK-antibody positive myasthenia gravis patients

Muscle specific tyrosine kinase antibody positive myasthenia gravis (MuSK- MG) is characterized by autoantibodies against the MuSK protein of the neuromuscular junction resulting in weakness of bulbar and proximal muscles. We previously demonstrated that patients with MuSK-MG have increased pro-inflammatory Th1 and Th17 responses. Tacrolimus, an immunosuppressant used in AChR-MG and transplantation patients, inhibits T cell responses through interference with IL-2 transcription. The therapeutic efficacy and immunological effect of tacrolimus in MuSK-MG is unclear. In the current study we examined the proliferation, phenotype and cytokine production of CD4+ and CD8+ T cells in peripheral blood mononuclear cells of MuSK-MG following a 3-day in vitro culture with or without tacrolimus. We determined that tacrolimus profoundly suppressed CD4 and CD8 T cell proliferation and significantly suppressed Th1 and Th17 responses, as demonstrated by a reduced frequency of IFN-γ, IL-2, and IL-17 producing CD4 T cells and reduced frequencies of IFN-γ and IL-2 producing CD8 T cells. Tacrolimus also inhibits pathogenic Th17 cells coproducing IL-17 and IFN-γ. In addition, tacrolimus suppressed follicular T helper cell (Tfh) and regulatory T helper cell (Treg) subsets. These findings provide preliminary support for tacrolimus as a potential alternative immunosuppressive therapy for MuSK-MG.

Tacrolimus Improves Symptoms of Children With Myasthenia Gravis Refractory to Prednisone

BACKGROUND

Myasthenia gravis tends to affect children in China. Oral pyridostigmine and prednisone could effectively improve the symptoms, but multiple side effects become a major concern after long-term oral prednisone. To avoid the long-term complications of prednisone therapy and to obtain more satisfactory improvement, we tested the efficacy and safety of tacrolimus in children with myasthenia gravis.

METHODS

Children with myasthenia gravis who had not achieved satisfactory improvement or who experienced severe side effects after prednisone therapy were recruited between January 2015 and December 2016 at Tongji Hospital. All the children were treated with tacrolimus 1 mg to 2 mg daily and the dose was adjusted on the basis of the clinical response and the serum concentration. The dosage of prednisone, the severity of symptoms, blood samples, the serum concentration of tacrolimus, and titers of antiacetylcholine receptor antibodies were evaluated every four weeks.

RESULTS

Fourteen children were enrolled. One child withdrew two weeks after the enrollment. Thirteen children have completed the therapy for one year. At the end point, the dosage of prednisone was significantly decreased (P < 0.05), the symptoms were evaluated by the quantitative myasthenia gravis score, and myasthenia gravis-specific manual muscle testing and myasthenia gravis-activities of daily living scores were significantly improved (P < 0.05, P < 0.05, and P < 0.01, respectively). More importantly, ten (76.9%) patients had completely discontinued prednisone, and the major side effects were nearly reversed. The mean titer of antiacetylcholine receptor antibodies significantly dropped from 1.96±2.62 nmol/L to 0.70±1.04 nmol/L (P < 0.05). No severe adverse events were reported.

CONCLUSIONS

Our results suggest that tacrolimus is a promising agent for children with refractory myasthenia gravis. Randomized clinical trials are needed to confirm the observation.

Rapamycin alleviates inflammation and muscle weakness, while altering the Treg/Th17 balance in a rat model of myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disease commonly treated with immunosuppressants. We evaluated the novel immunosuppressant, rapamycin (RAPA), in a rat model of experimental autoimmune MG (EAMG). Mortality rates in the RAPA (12%) were significantly down compared with the EAMG (88%) or cyclophosphamide (CTX) (68%) intervention groups. Muscular weakness decreased after both RAPA and CTX treatment. However, Lennon scores were lower (1.74 ± 0.49, 3.39 ± 0.21, and 3.81 ± 0.22 in RAPA, CTX, and EAMG groups, respectively), and body weights (203.12 ± 4.13 g, 179.23 ± 2.13 g, and 180.13 ± 5.13 g in RAPA, CTX, and EAMG groups, respectively) were significantly higher, only in the RAPA group. The proportion of regulatory T cells (Treg) significantly increased, while that of Th17 cells significantly decreased in the RAPA group compared with the EAMG group. In comparison, CTX intervention resulted in increased Th17 but significantly decreased Tregs. Hence, RAPA can be more effectively used in comparison with CTX to treat MG, with an efficacy higher than that of CTX. In addition, our results suggest RAPA’s efficacy in alleviating symptoms of MG stems from its ability to correct the Treg/Th17 imbalance observed in MG.

Mechanisms of Autoantibody-Induced Pathology

Autoantibodies are frequently observed in healthy individuals. In a minority of these individuals, they lead to manifestation of autoimmune diseases, such as rheumatoid arthritis or Graves' disease. Overall, more than 2.5% of the population is affected by autoantibody-driven autoimmune disease. Pathways leading to autoantibody-induced pathology greatly differ among different diseases, and autoantibodies directed against the same antigen, depending on the targeted epitope, can have diverse effects. To foster knowledge in autoantibody-induced pathology and to encourage development of urgently needed novel therapeutic strategies, we here categorized autoantibodies according to their effects. According to our algorithm, autoantibodies can be classified into the following categories: (1) mimic receptor stimulation, (2) blocking of neural transmission, (3) induction of altered signaling, triggering uncontrolled (4) microthrombosis, (5) cell lysis, (6) neutrophil activation, and (7) induction of inflammation. These mechanisms in relation to disease, as well as principles of autoantibody generation and detection, are reviewed herein.

T-cell responses to distinct AQP4 peptides in patients with neuromyelitis optica (NMO)

BACKGROUND

Although antibodies to aquaporin-4(AQP4) are strongly associated with Neuromyelitis optica (NMO), the sole transfer of these antibodies is not sufficient to induce an NMO-like disease in experimental animals and T-cells and complement are also needed. Initial data indicating the presence of T-cell responses to AQP4 in patients with NMO, have beeen recently reported.

OBJECTIVE

To evaluate the T-cell responses to specific AQP4 peptides/epitopes in patients with NMO and multiple sclerosis (MS).

METHODS

Peripheral blood mononuclear cells (PBMCs) were obtained from 14 patients fulfilling the criteria for definite NMO and the proliferation responses to one of 15 distinct pentadecapeptides of AQP4, spanning the whole protein (except of its transmembrane parts) were tested by a standard [H3]-thymidine uptake assay and compared with those of 9 healthy controls and 7 MS patients. A cytometric bead array assay (CBA) and flow cytometry were used to evaluate cytokine (IFNγ, IL17, IL2, IL4, IL5, IL10 and TNFα) and chemokine (CXCL8, CCL5, CXCL10, CXCL9, CCL2) secretion by PHA-stimulated PBMCs and AQP4-specific T-cell lines.

RESULTS

Four main immunodominant epitopes of the AQP4 protein (p137-151, p222-236, p217-231 and the p269-283) were identified in the NMO group. The first two epitopes (assigned as peptides 3 and 9) showed the highest sensitivity (~60% positivity), whereas the latter two (assigned as peptides 8 and 11), the higher specificity. Longitudinal follow up of 5 patients revealed changes in the epitope-specificities during the course of NMO. T-cell lines specific for the AQP4 peptides, produced from NMO patients (but not healthy donors) secreted mainly IL-17 and IL-10 and less IFNγ.

CONCLUSIONS

Our findings indicate that T-cells bearing characteristics of both Th1 and Th17 T-cells and targeting specific immunodominant epitopes of the AQP4 protein might be involved in the pathogenesis of NMO.

Low and high doses of ursolic acid ameliorate experimental autoimmune myasthenia gravis through different pathways

Myasthenia gravis (MG) is an autoimmune disease characterized by fatigable muscle weakness. Ursolic acid (UA) is a pentacyclic triterpenoid with anti-inflammatory and immunomodulatory properties, especially inhibiting IL-17. We found that UA ameliorated the symptoms of experimental autoimmune myasthenia gravis (EAMG), a rat model of MG. Although both the low and high doses of UA shifted Th17 to Th2 cytokines, other mechanisms were dose dependent. The low dose enhanced Fas-mediated apoptosis, whereas the high dose up-regulated Treg cells and reduced the concentrations of IgG2b antibodies. These findings suggest a new strategy to treat EAMG and even human MG.

Recombinant IgG2a Fc (M045) multimers effectively suppress experimental autoimmune myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disorder caused by target-specific pathogenic antibodies directed toward postsynaptic neuromuscular junction (NMJ) proteins, most commonly the skeletal muscle nicotinic acetylcholine receptor (AChR). In MG, high-affinity anti-AChR Abs binding to the NMJ lead to loss of functional AChRs, culminating in neuromuscular transmission failure and myasthenic symptoms. Intravenous immune globulin (IVIg) has broad therapeutic application in the treatment of a range of autoimmune diseases, including MG, although its mechanism of action is not clear. Recently, the anti-inflammatory and anti-autoimmune activities of IVIg have been attributed to the IgG Fc domains. Soluble immune aggregates bearing intact Fc fragments have been shown to be effective treatment for a number of autoimmune disorders in mice, and fully recombinant multimeric Fc molecules have been shown to be effective in treating collagen-induced arthritis, murine immune thrombocytopenic purpura, and experimental inflammatory neuritis. In this study, a murine model of MG (EAMG) was used to study the effectiveness of this novel recombinant polyvalent IgG2a Fc (M045) in treating established myasthenia, with a direct comparison to treatment with IVIg. M045 treatment had profound effects on the clinical course of EAMG, accompanied by down-modulation of pathogenic antibody responses. These effects were associated with reduced B cell activation and T cell proliferative responses to AChR, an expansion in the population of FoxP3(+) regulatory T cells, and enhanced production of suppressive cytokines, such as IL-10. Treatment was at least as effective as IVIg in suppressing EAMG, even at doses 25-30 fold lower. Multimeric Fc molecules offer the advantages of being recombinant, homogenous, available in unlimited quantity, free of risk from infection and effective at significantly reduced protein loads, and may represent a viable therapeutic alternative to polyclonal IVIg.

Characterization of CD4 and CD8 T cell responses in MuSK myasthenia gravis

Muscle specific tyrosine kinase myasthenia gravis (MuSK MG) is a form of autoimmune MG that predominantly affects women and has unique clinical features, including prominent bulbar weakness, muscle atrophy, and excellent response to therapeutic plasma exchange. Patients with MuSK MG have predominantly IgG4 autoantibodies directed against MuSK on the postsynaptic muscle membrane. Lymphocyte functionality has not been reported in this condition. The goal of this study was to characterize T cell responses in patients with MuSK MG. Intracellular production of IFN-gamma, TNF-alpha, IL-2, IL-17, and IL-21 by CD4+ and CD8+ T cells was measured by polychromatic flow cytometry in peripheral blood samples from 11 Musk MG patients and 10 healthy controls. Only one MuSK MG patient was not receiving immunosuppressive therapy. Regulatory T cells (Treg) were also included in our analysis to determine if changes in T cell function were due to altered Treg frequencies. CD8+ T cells from MuSK MG patients had higher frequencies of polyfunctional responses than controls, and CD4+ T cells had higher IL-2, TNF-alpha, and IL-17. MuSK MG patients had a higher percentage of CD4+ T cells producing combinations of IFN-gamma/IL-2/TNF-gamma, TNF-alpha/IL-2, and IFN-gamma/TNF-alpha. Interestingly, Treg numbers and CD39 expression were not different from control values. MuSK MG patients had increased frequencies of Th1 and Th17 cytokines and were primed for polyfunctional proinflammatory responses that cannot be explained by a defect in CD39 expression or Treg number.

Impairment of regulatory T cells in myasthenia gravis: studies in an experimental model

Myasthenia gravis (MG) is an antibody mediated, T cell dependent autoimmune disease characterized by muscle fatigability in which autoantibodies directed to the acetylcholine receptor (AChR) impair neuromuscular transmission. The identification of CD4⁺CD25⁺Foxp3⁺Treg cells as important regulators of tolerance opened a major area of investigation raising the possibility that a dysfunction in the Treg compartment is involved in the etiology and pathogenesis of autoimmune diseases, including MG. In this paper we summarize shortly Treg abnormalities that were reported in MG patients and report on our studies of Treg in experimental autoimmune MG (EAMG). Hopefully these studies would pave the way towards the development of novel Treg-based treatment modalities that will restore self-tolerance in MG and other autoimmune diseases. In our previous studies in EAMG we have shown that Treg cells transferred from healthy rat donors to myasthenic rats suppress EAMG. However, Treg cells from sick animals do not have the same in vivo suppressive activity as those from healthy donors. The objective of the present study was to further characterize quantitative and qualitative alterations in Treg cells of rats with EAMG. We found that the frequency of CD4⁺CD25⁺Foxp3⁺Treg cells within the spleen and PBL was decreased in EAMG rats as compared to naïve and CFA-immunized healthy controls. Treg cells from myasthenic rats were less effective than Treg cells from controls in suppressing the proliferation of CD4⁺T effector cells in response to ConA and of B cells in response to LPS. Moreover, CD4⁺CD25⁺ cells from EAMG rats exhibited an elevated extent of apoptosis and expressed upregulated levels of FAS and of Th17-associated cytokines. Since EAMG is an induced disease, these quantitative and qualitative alterations in Treg cells do not reflect predisposing impairments and seem to be associated with the specific autoimmune response resulting from AChR immunization.

FOXP3 -3279 and IVS9+459 polymorphisms are associated with genetic susceptibility to myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disorder in which CD4(+)CD25(+) FOXP3(+)regulatory T cells (Tregs) are thought to play important roles in driving the ongoing autoimmune response. Although it is known that single-nucleotide polymorphisms (SNPs) in the fork head/winged-helix transcription factor 3 (FOXP3) gene contribute to some autoimmune diseases, information about the role of this gene in MG is limited. We therefore evaluated the association between FOXP3 gene SNPs and susceptibility to MG in a Han Chinese population. In a hospital-based, case-control study, two SNPs in the FOXP3 gene (-3279 and IVS9+459) were investigated in 118 MG and 124 healthy controls, and their relationship with the four parameters of gender, onset age, thymus pathology, and clinical classification of MG were performed with a stratified analysis. We found that the frequency of the FOXP3 IVS9+459 G allele was significantly lower in MG patients than in healthy controls (P=0.041), while the frequency of the FOXP3 -3279 polymorphisms was not significantly different between the two groups. Our results suggest that FOXP3 IVS9+459 polymorphisms appear to have an effect on the risk of MG in a Han Chinese population, and the G allele may be a genetic protective factor to MG.

A decrease in the percentage of CD3+ cells is correlated with clinical improvement during plasmapheresis in patients with myasthenia gravis

Plasmapheresis not only removes circulating antibodies but also modulates cellular immunity, including lymphocyte subsets. To investigate the effect of double-filtration plasmapheresis (DFPP) on the ratio of lymphocyte subsets in patients with myasthenia gravis (MG), we examined the percentages of B-cells, T-cells, T helper (Th) cells, T suppressor (Ts) cells, natural killer (NK) cells, NKT cells, and Th/Ts ratio before and after a single DFPP session and after a course of DFPP. A total of 26 patients were recruited; their peripheral blood lymphocyte subsets were assayed using flow cytometry. After a single session of DFPP treatment, the percentages of T-cells (P = 0.0200), Th cells (P = 0.0178), and the Th/Ts ratio (P = 0.0309) decreased significantly, whereas the percentage of NK cells (P = 0.0007) increased significantly. More importantly, after one course of DFPP treatment, the reduced clinical quantitative MG (QMG) score was correlated with the decrease of the percentage of T-cells (r = 0.5005, P = 0.0092). Fourteen thymectomized MG patients had decreased percentages of T-cells (P = 0.0304) and Th cells (P = 0.0444), whereas they had increased NK cells (P = 0.0197) after a single DFPP session. Here, transiently decreased percentages of T-cells after the full DFPP course could enhance the effectiveness of plasmapheresis for MG patients.

DAF/CD55 and Protectin/CD59 modulate adaptive immunity and disease outcome in experimental autoimmune myasthenia gravis

The role of regulators of complement activity (RCA) involving CD55 and CD59 in the pathogenesis of experimental autoimmune myasthenia gravis (EAMG) remains unclear. CD55 and CD59 restrict complement activation by inhibiting C3/C5 convertases' activities and membrane attack complex formation, respectively. Actively immunized EAMG mice deficient in either CD55 or CD59 showed significant differences in adaptive immune responses and worsened disease outcome associated with increased levels of serum cytokines, modified production of acetylcholine receptor antibodies, and more complement deposition at the neuromuscular junction. We conclude that modulation of complement activity by RCA represents an alternative in controlling of autoimmune processes in EAMG.

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.

Clinical efficacy and immunological impact of tacrolimus in Chinese patients with generalized myasthenia gravis

In this multicenter, open-label pilot study, the efficacy, safety, and immunological impact of tacrolimus in Chinese patients with generalized myasthenia gravis are assessed. Forty-seven generalized myasthenia gravis (MG) patients were enrolled into this study and given 3mg/day tacrolimus for 24 weeks. The primary efficacy measurements used to monitor response to tacrolimus in MG patients were the Osserman grade, the quantitative MG score (QMGS) recommended by the MGFA, the MG-specific manual muscle testing (MMT) score, and the MG-related activities of daily living (MG-ADL) scale. Also, reduction in steroid doses was used to monitor the effect of tacrolimus. Clinical evaluations were conducted at weeks 4, 8, 12, 16, 20, and 24, while immunological parameters were measured at weeks 4, 12, and 24. Measurements of the Osserman grade, QMGS, MMT, and MG-ADL all suggested improvement in patient health by the fourth week of treatment. Steroid dosage was reduced during the course of the study in 74.2% of the forty-three patients who completed the study. There were thirty-one reported adverse events in the study. Only one was considered serious. We found that tacrolimus reduced levels of the IFN-γ, IL-2, IL-10, and IL-13 cytokines and induced the proliferation of tolerogenic plasmacytoid dendritic cells after treatment. Tacrolimus did not change the population of T cell subtypes but did steadily reduce the population of BAFF-R(+) CD19(+) B cells over the course of the study. Our results show that tacrolimus improves the clinical condition of MG patients and is well tolerated. The decrease in IL-13 and reduction of BAFF-R(+) CD19(+) B cells may be related to the therapeutic effect of tacrolimus.

Antibody effector mechanisms in myasthenia gravis-pathogenesis at the neuromuscular junction

Myasthenia gravis (MG) is an autoimmune disorder caused by autoantibodies that are either directed to the muscle nicotinic acetylcholine receptor (AChR) or to the muscle-specific tyrosine kinase (MuSK). These autoantibodies define two distinct subforms of the disease-AChR-MG and MuSK-MG. Both AChR and MuSK are expressed on the postsynaptic membrane of the neuromuscular junction (NMJ), which is a highly specialized region of the muscle dedicated to receive and process signals from the motor nerve. Autoantibody binding to proteins of the postsynaptic membrane leads to impaired neuromuscular transmission and muscle weakness. Pro-inflammatory antibodies of the human IgG1 and IgG3 subclass modulate the AChR, cause complement activation, and attract lymphocytes; together acting to decrease levels of the AChR and AChR-associated proteins and to reduce postsynaptic folding. In patients with anti-MuSK antibodies, there is no evidence of loss of junctional folds and no apparent loss of AChR density. Anti-MuSK antibodies are predominantly of the IgG4 isotype, which functionally differs from other IgG subclasses in its anti-inflammatory activity. Moreover, IgG4 undergoes a posttranslational modification termed Fab arm exchange that prevents cross-linking of antigens. These findings suggest that MuSK-MG may be different in etiological and pathological mechanisms from AChR-MG. The effector functions of IgG subclasses on synapse structure and function are discussed in this review.

Current and future immunotherapy in myasthenia gravis

Current therapy for myasthenia gravis is directed towards generalized modulation and suppression of the immune system. These approaches have been extensively studied and are effective in many patients with myasthenia, but at the cost of significant adverse effects due to the global effects on the immune system. Future directions in therapy are geared towards focused immunotherapies that aim to improve outcomes while lessening the burden of side effects. This paper reviews both the current accepted treatments for myasthenia gravis as well as promising targeted therapies in development.

Interleukin-10 promoter polymorphisms in myasthenia gravis

Interleukin 10 (IL-10) is secreted by several hemopoietic cells and suppresses the Th1 mediated immune response, while stimulating B cell differentiation and the humoral immune response. IL-10 expression in Con A-stimulated peripheral blood mononuclear cells is related to three polymorphisms in the promoter region of the IL-10 gene; G/A at position -1082, T/C at position -819 and A/C at position -592. We analyzed the distribution of these IL-10 polymorphisms in 64 MG patients and 87 healthy blood donors to determine any influence on MG susceptibility. MG patients had a significantly higher frequency of the ACC/ACC haplotype (12.5% vs 3.4% in controls), as had the subgroups with late onset MG and thymomatous MG (20.0% and 21.4%, respectively). Early onset MG patients had a high frequency of the ATA/ATA haplotype (19.2% vs 3.4% in controls). Titin Ab-positive MG patients had high ACC/ACC (20.0%). This study indicates a direct link between IL-10 and MG pathogenesis, although the complex role of this multi-faceted cytokine in vivo is as yet not fully elucidated.

Experimental autoimmune myasthenia gravis in the mouse

Myasthenia gravis (MG) is a T cell-dependent antibody-mediated autoimmune neuromuscular disease. Antibodies to the nicotinic acetylcholine receptor (AChR) destroy the AChR, thus leading to defective neuromuscular transmission of electrical impulse and to muscle weakness. This unit is a practical guide to the induction and evaluation of experimental autoimmune myasthenia gravis (EAMG) in the mouse, the animal model for MG. Protocols are provided for the extraction and purification of AChR from the electric organs of Torpedo californica, or eel. The purified receptor is used as an immunogen to induce autoimmunity to AChR, thus causing EAMG. The defect in neuromuscular transmission can also be measured quantitatively by electromyography, as described here. In addition, EAMG is frequently characterized by the presence of antibodies to AChR, which are measured by radioimmunoassay and by a marked antibody-mediated reduction in the number of muscle AChRs. AChR extracted from mouse muscle is used in measuring serum antibody levels and for quantifying muscle AChR content.