Imbalance of Th17 and Tregs in thymoma may be a pathological mechanism of myasthenia gravis

Circulating CD45RA-Foxp3++ Treg cells serve as a biomarker for predicting minimal clinical manifestations status of myasthenia gravis

AIMS

Regulatory T cells (Tregs) are key mediators of the induction of immune tolerance; however, the mechanisms by which they regulate myasthenia gravis (MG) are not fully understood. This study aimed to explore the characteristics of Tregs and their subpopulations in the peripheral blood of patients with minimal clinical manifestations (MM) of MG and identify biomarkers that predict MM-MG for treatment guidance.

MATERIALS AND METHODS

The clinical data of patients with general MG who visited our hospital were retrospectively analyzed. Age- and sex-matched volunteers were selected as healthy controls (HC). Flow cytometry was used to determine the proportion, function, and subpopulations of total Tregs. A correlation analysis was conducted for subpopulation proportions and MG disease severity.

KEY FINDINGS

A total of 27 cases of MM-MG, 40 cases of naїve-MG, and 33 cases of HC were included in this study. The number of total Tregs and the suppressive function of total Tregs were elevated in patients with MM-MG compared to those of patients with naїve-MG. Further analysis revealed that the frequency of CD45RA-Foxp3++ Tregs (a-Tregs) negatively correlated with quantitative myasthenia gravis (QMG) scores for patients with naїve-MG. In addition, the number of a-Tregs was significantly greater in patients with MM-MG than in patients with naїve-MG, and CD45RA-Foxp3+ Tregs expressed higher and lower levels of CTLA-4 and CXCR3, respectively.

SIGNIFICANCE

CD45RA-Foxp3++ Tregs were significantly more abundant and highly expressed surface inhibitory molecules in patients with MM-MG. This profile may serve as a predictive biomarker for MM-MG.

BMSCs-Derived Extracellular VesiclemiR-29a-3p Improved the Stability of Rat Myasthenia Gravis by Regulating Treg/Th17 Cells

INTRODUCTION

Myasthenia gravis (MG) is an autoimmune disorder. Microvesicle-derived miRNAs have been implicated in autoimmune diseases. However, the role of microvesicle-derived miR-29a-3p in MG remains poorly understood. This study aimed to investigate the therapeutic effect and mechanism of miR-29a-3p derived from stem cell microvesicles (MVs) on experimental autoimmune myasthenia gravis (EAMG) rats.

METHODS

EAMG was induced in rats by injection of the subunit of the rat nicotinic anti-acetylcholine receptor (AChR) R97-116 peptide.Besides the control group, EAMG rats were randomly allocated into the EAMG model group, MV group, MV-NC-agomir group, and MV- miR-29a-3p-agomir group.

RESULTS

Our results found that BMSCs-MV promoted miR-29a-3p expression in gastrocnemius of EAMG rats. Bone marrow mesenchymal stem cells (BMSCs) derived microvesicle miR-29a-3p improved the hanging ability and swimming time of EMGA rats and weakened the degree of muscle fiber atrophy. Furthermore, microvesicles from miR-29a-3p overexpressing BMSCs reduced the content of AchR-Ab in the serum of EAMG rats. BMSC-derived microvesicle miR-29a-3p further suppressed the expression of IFN-γ and enhanced the IL-4 and IL-10 in the serum of EAMG rats by restoring the Th17/Treg cells balance.

DISCUSSION

BMSCs-derived microvesicle miR-29a-3p improved the stability of rat myasthenia gravis by regulating Treg/Th17 cells. It may be an effective treatment for MG.

Improving regulatory T cell-based therapy: insights into post-translational modification regulation

Regulatory T (Treg) cells are pivotal for maintaining immune homeostasis and play essential roles in various diseases, such as autoimmune diseases, graft-versus-host disease (GVHD), tumors, and infectious diseases. Treg cells exert suppressive function via distinct mechanisms, including inhibitory cytokines, granzyme or perforin-mediated cytolysis, metabolic disruption, and suppression of dendritic cells. Forkhead Box P3 (FOXP3), the characteristic transcription factor, is essential for Treg cell function and plasticity. Cumulative evidence has demonstrated that FOXP3 activity and Treg cell function are modulated by a variety of post-translational modifications (PTMs), including ubiquitination, acetylation, phosphorylation, methylation, glycosylation, poly(ADP-ribosyl)ation, and uncharacterized modifications. This review describes Treg cell suppressive mechanisms and summarizes the current evidence on PTM regulation of FOXP3 and Treg cell function. Understanding the regulatory role of PTMs in Treg cell plasticity and function will be helpful in designing therapeutic strategies for autoimmune diseases, GVHD, tumors, and infectious diseases.

Baricitinib as a treatment for myasthenia gravis: a case report

Myasthenia gravis (MG) is an autoimmune disease that targets neuromuscular junctions. While immunotherapy remains the cornerstone of treatment, the effects of Janus kinase (JAK) inhibitors on MG remain underexplored. In this report, we describe the case of a 58-year-old woman with ocular myasthenia gravis who received treatment with the JAK inhibitor, baricitinib for alopecia areata. The patient presented with left eyelid ptosis and an inadequate response to steroids and pyridostigmine, along with symptoms of alopecia areata. Following diagnosis, we initiated a treatment regimen consisting of baricitinib for six months. After initiation of baricitinib, we observed a complete resolution of the patient's MG symptoms, accompanied by hair regrowth, even when steroids were tapered and pyridostigmine was discontinued. Furthermore, the titer of the anti-acetylcholine receptor antibody was decreased. This report represents the first reported case of anti-acetylcholine receptor antibody-positive MG that was successfully treated through the inhibition of JAK activity.

Nanodrug Delivery Systems for Myasthenia Gravis: Advances and Perspectives

Myasthenia gravis (MG) is a rare chronic autoimmune disease caused by the production of autoantibodies against the postsynaptic membrane receptors present at the neuromuscular junction. This condition is characterized by fatigue and muscle weakness, including diplopia, ptosis, and systemic impairment. Emerging evidence suggests that in addition to immune dysregulation, the pathogenesis of MG may involve mitochondrial damage and ferroptosis. Mitochondria are the primary site of energy production, and the reactive oxygen species (ROS) generated due to mitochondrial dysfunction can induce ferroptosis. Nanomedicines have been extensively employed to treat various disorders due to their modifiability and good biocompatibility, but their application in MG management has been rather limited. Nevertheless, nanodrug delivery systems that carry immunomodulatory agents, anti-oxidants, or ferroptosis inhibitors could be effective for the treatment of MG. Therefore, this review focuses on various nanoplatforms aimed at attenuating immune dysregulation, restoring mitochondrial function, and inhibiting ferroptosis that could potentially serve as promising agents for targeted MG therapy.

Thymic gene expression analysis reveals a potential link between HIF-1A and Th17/Treg imbalance in thymoma associated myasthenia gravis

Myasthenia gravis (MG) is an immune-mediated disease frequently associated with thymic changes. Increased T helper 17 (Th17) cell activity and dysfunctional regulatory T (Treg) cells have been demonstrated in subgroups of MG. On the other hand, hypoxia-inducible factor 1 (HIF-1) has been shown to regulate the Th17/Treg balance by inducing Th17 differentiation while attenuating Treg development. To identify the underlying mechanisms of different thymic pathologies in MG development, we evaluated thymic samples from thymoma-associated myasthenia gravis (TAMG), MG with hyperplasia (TFH-MG) and thymoma without MG (TOMA) patients. Differential gene expression analysis revealed that TAMG and TFH-MG cells are associated with different functional pathways. A higher RORC/FOXP3 ratio provided evidence for Th17/Treg imbalance in TAMG potentially related to increased HIF1A. The hypoxic microenvironment in thymoma may be a driver of TAMG by increasing HIF1A. These findings may lead to new therapeutic approaches targeting HIF1A in the development of TAMG.

IL-6 receptor antibody treatment improves muscle weakness in experimental autoimmune myasthenia gravis mouse model

Myasthenia gravis (MG) is a chronic autoimmune disease characterized by muscle weakness and fatigue. It is caused by pathological autoantibodies against components expressed at neuromuscular junctions, such as acetylcholine receptor (AChR). Interleukin-6 (IL-6) has been suggested to play a role in the pathogenesis of MG, and IL-6 receptor (IL-6R) antibody treatment may provide a novel therapeutic option. In this study, we investigated the effects of IL-6R antibody treatment in an experimental autoimmune MG (EAMG) mouse model. We demonstrated that IL-6R antibody treatment improved muscle weakness, reduced IgG deposition at neuromuscular junctions, and the levels of AChR autoantibodies in serum. In addition, follicular helper T cells and Th17, plasma cells in lymph nodes were lower in IL-6R antibody treated mice. Our findings suggest that IL-6R blockade may be a novel and effective therapeutic strategy for the treatment of MG.

Unique association of anti-GABAA receptor encephalitis and myasthenia gravis in a patient with type A thymoma

Association between anti-GABAAR encephalitis and myasthenia gravis is extremely rare with few reported cases. Herein, we report a case of a female patient diagnosed with anti-GABAAR encephalitis and thymoma at the first admission. She was administered glucocorticoids for long-term immunotherapy, and thymectomy with biopsy demonstrated a type A thymoma. After 4 months, the symptoms of encephalitis were relieved, but she then developed post-thymectomy myasthenia gravis with anti-AChR and anti-titin dual positivity. Antibodies to connective tissue (anti-ANA, anti-PCNA) and those characteristics of paraneoplastic syndrome (anti-Ma2/Ta) were also positive. She received oral glucocorticoids and tacrolimus as immunosuppressive therapy, and myasthenic symptoms were stable during a 2-year follow-up. Our case revealed that anti-GABAAR encephalitis and myasthenia gravis can appear in patient with type A thymoma at different periods, which alerts physicians to take long-term follow-up for anti-GABAAR encephalitis with thymoma, even after thymectomy. Concurrent positivity for more than one antibody after thymectomy is rarely observed, and their contribution to the clinical course and treatment decision remains to be further investigated.

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.

Thymoma patients with or without myasthenia gravis have increased Th17 cells, IL-17 production and ICOS expression

Thymoma associated myasthenia gravis (TAMG) is a small disease subgroup with autoantibodies against the acetylcholine receptor. The aim of this study was to assess the role of T helper (Th) cells in TAMG compared to thymoma patients without MG (TOMA) and healthy controls (HC). Peripheral blood cells were used for intracellular cytokine measurements and phenotyping of CD4+ Th cells. IL-21 and IL-4 productions and peripheral Th cells were higher in TAMG compared to TOMA patients and HC. Increases of ICOS and Th17 population were detected both in TAMG and TOMA groups. Higher IL-10 and Th1 population have been observed related to thymectomy. ICOS expression and Th17 induced by thymoma may contribute to the development of TAMG.

Understanding the landscape of immunotherapy in thymic epithelial tumors

Thymic epithelial tumors (TETs) are a rare group of malignancies arising from the thymus. Surgery remains the foundation of treatment for patients with early-stage disease. Limited treatment options are available for the treatment of unresectable, metastatic, or recurrent TETs and are associated with modest clinical efficacy. The emergence of immunotherapies in the treatment of solid tumors has generated significant interest in understanding their role in TET treatment. However, the high rates of comorbid paraneoplastic autoimmune disorders, particularly in thymoma, have tempered expectations regarding the role of immune-based therapies. Clinical studies of immune checkpoint blockade (ICB) in thymoma and thymic carcinoma have revealed higher frequencies of immune-related adverse events (IRAEs) and limited efficacy. Despite these setbacks, the growing understanding of the thymic tumor microenvironment and systemic immune system has advanced the understanding of these diseases and provided opportunities for novel immunotherapy modalities. Ongoing studies are evaluating numerous immune-based treatments in TETs with the goal of improving clinical efficacy and mitigating IRAE risk. This review will provide insight into the current understanding of the thymic immune microenvironment, outcomes of previous ICB studies, and review treatments currently being explored for the management of TET.

A comprehensive pancancer analysis reveals the potential value of RAR-related orphan receptor C (RORC) for cancer immunotherapy

Background: RAR-related orphan receptor C (RORC) plays an important role in autoimmune responses and inflammation. However, its function in cancer immunity is still unclear. Its potential value in cancer immunotherapy (CIT) needs to be further studied. Methods: Expression and clinical data for 33 cancers were obtained from UCSC-Xena. The correlation between RORC expression and clinical parameters was analyzed using the limma software package to assess the prognostic value of RORC. Timer2.0 and DriverDBv3 were used to analyze the RORC mutation and methylation profiles. RORC-associated signaling pathways were identified by GSEA. The correlations of RORC expression with tumor microenvironment factors were further assessed, including immune cell infiltration (obtained by CIBERSORT) and immunomodulators (in pancancer datasets from the Tumor-Immune System Interactions and Drug Bank [TISIDB] database). In addition, the correlations of RORC with four CIT biomarkers (tumor mutational burden, microsatellite instability, programmed death ligand-1, and mismatch repair) were explored. Furthermore, three CIT cohorts (GSE67501, GSE168204, and IMvigor210) from the Gene Expression Omnibus database and a previously published study were used to determine the association between RORC expression and CIT response. Results: RORC was differentially expressed in many tumor tissues relative to normal tissues (20/33). In a small number of cancers, RORC expression was correlated with age (7/33), sex (4/33), and tumor stage (9/33). Furthermore, RORC expression showed prognostic value in many cancers, especially in kidney renal clear cell carcinoma (KIRC), brain lower grade glioma (LGG), and mesothelioma (MESO). The mutation rate of RORC in most cancer types was low, while RORC was hypermethylated or hypomethylated in multiple cancers. RORC was associated with a variety of biological processes and signal transduction pathways in various cancers. Furthermore, RORC was strongly correlated with immune cell infiltration, immunomodulators, and CIT biomarkers. However, no significant association was found between RORC and CIT response in the three CIT cohorts. Conclusion Our findings revealed the potential immunotherapeutic value of RORC for various cancers and provides preliminary evidence for the application of RORC in CIT.

Immunological signature of patients with thymic epithelial tumors and Good syndrome

Background

Thymic epithelial tumors (TETs) are frequently accompanied by Good Syndrome (GS), a rare immunodeficiency, characterized by hypogammaglobulinemia and peripheral B cell lymphopenia. TETs can be also associated to other immunological disorders, both immunodeficiency and autoimmunity.

Methods

In this study, we enrolled TET patients with GS to address differences between patients with or without associated autoimmune diseases (AD). We analyzed the immunophenotype from peripheral blood of these patients focusing on selected immune cell subsets (CD4+T cells, CD8+T cells, T regulatory cells, NK cells, B-cells, monocytes, eosinophils, basophils, neutrophils) and serum levels of cytokines, chemokines and growth factors.

Results

We observed higher number of leucocytes, in particular lymphocytes, B lymphopenia and lower number of T regulatory cells in TET patients with associated AD compared to TET patients without AD. In the group of TET patients with AD, we also observed increased serum levels of IL-15, VEGF, IP-10, GM-CSF, IL-6, and MIP-1α. Thus, we identified considerable differences in the lymphocyte profiles of TET patients with and without ADs, in particular a reduction in the numbers of B lymphocytes and T-regulatory cells in the former, as well as differences in the serum levels of various immune modulators.

Conclusions

Although the pathogenic mechanisms are still unclear, our results add new knowledge to better understand the disease, suggesting the need of surveilling the immunophenotype of TET patients to ameliorate their clinical management.