Analysis of serum miRNA profiles of myasthenia gravis patients

Metal-organic framework (MOF)-based biosensors for miRNA detection

MicroRNAs (miRNAs) play several crucial roles in the physiological and pathological processes of the human body. They are considered as important biomarkers for the diagnosis of various disorders. Thus, rapid, sensitive, selective, and affordable detection of miRNAs is of great importance. However, the small size, low abundance, and highly similar sequences of miRNAs impose major challenges to their accurate detection in biological samples. In recent years, metal-organic frameworks (MOFs) have been applied as promising sensing materials for the fabrication of different biosensors due to their distinctive characteristics, such as high porosity and surface area, tunable pores, outstanding adsorption affinities, and ease of functionalization. In this review, the applications of MOFs and MOF-derived materials in the fabrication of fluorescence, electrochemical, chemiluminescence, electrochemiluminescent, and photoelectrochemical biosensors for the detection of miRNAs and their detection principle and analytical performance are discussed. This paper attempts to provide readers with a comprehensive knowledge of the fabrication and sensing mechanisms of miRNA detection platforms.

The intricate dance of non-coding RNAs in myasthenia gravis pathogenesis and treatment

Myasthenia gravis (MG) stands as a perplexing autoimmune disorder affecting the neuromuscular junction, driven by a multitude of antibodies targeting postsynaptic elements. However, the mystery of MG pathogenesis has yet to be completely uncovered, and its heterogeneity also challenges diagnosis and treatment. Growing evidence shows the differential expression of non-coding RNAs (ncRNAs) in MG has played an essential role in the development of MG in recent years. Remarkably, these aberrantly expressed ncRNAs exhibit distinct profiles within diverse clinical subgroups and among patients harboring various antibody types. Furthermore, they have been implicated in orchestrating the production of inflammatory cytokines, perturbing the equilibrium of T helper 1 cells (Th1), T helper 17 cells (Th17), and regulatory T cells (Tregs), and inciting B cells to generate antibodies. Studies have elucidated that certain ncRNAs mirror the clinical severity of MG, while others may hold therapeutic significance, showcasing a propensity to return to normal levels following appropriate treatments or potentially foretelling the responsiveness to immunosuppressive therapies. Notably, the intricate interplay among these ncRNAs does not follow a linear trajectory but rather assembles into a complex network, with competing endogenous RNA (ceRNA) emerging as a prominent hub in some cases. This comprehensive review consolidates the landscape of dysregulated ncRNAs in MG, briefly delineating their pivotal role in MG pathogenesis. Furthermore, it explores their promise as prospective biomarkers, aiding in the elucidation of disease subtypes, assessment of disease severity, monitoring therapeutic responses, and as novel therapeutic targets.

Interactions Between Extracellular Vesicles and Autophagy in Neuroimmune Disorders

Neuroimmune disorders, such as multiple sclerosis, neuromyelitis optica spectrum disorder, myasthenia gravis, and Guillain-Barré syndrome, are characterized by the dysfunction of both the immune system and the nervous system. Increasing evidence suggests that extracellular vesicles and autophagy are closely associated with the pathogenesis of these disorders. In this review, we summarize the current understanding of the interactions between extracellular vesicles and autophagy in neuroimmune disorders and discuss their potential diagnostic and therapeutic applications. Here we highlight the need for further research to fully understand the mechanisms underlying these disorders, and to develop new diagnostic and therapeutic strategies.

Circulating miRNAs drive personalized medicine based on subgroup classification in myasthenia gravis patients

Myasthenia gravis (MG) is a classic autoimmune neuromuscular disease with strong clinical heterogeneity. The concept of subgroup classification was proposed to guide the precise treatment of MG. Subgroups based on serum antibodies and clinical features include ocular MG, early-onset MG with AchR antibodies, late-onset MG with AchR antibodies, thymoma-associated MG, MuSK-associated MG, LRP4-associated MG, and seronegative MG. However, reliable objective biomarkers are still needed to reflect the individualized response to therapy. MicroRNAs (miRNAs) are small non-coding RNA molecules which can specifically bind to target genes and regulate gene expression at the post-transcriptional level, and then influence celluar biological processes. MiRNAs play an important role in the pathogenesis of autoimmune diseases, including MG. Several studies on circulating miRNAs in MG have been reported. However, there is rare systematic review to summarize the differences of these miRNAs in different subgroups of MG. Here, we summarize the potential role of circulating miRNAs in different subgroups of MG to promote personalized medicine.

MicroRNA expression profiles of peripheral blood and mononuclear cells in myasthenia gravis: A systematic review

BACKGROUND

Studies have described the role of microRNAs (miRNAs) in thymic function, along with directly observing the altered expression of miRNAs in thymuses of myasthenia gravis (MG) patients; so, miRNAs became a core component in the pathophysiology of MG. However, because the miRNA analysis results are contradictory, the identification of MG-related miRNAs is daunting.

OBJECTIVE

We did a systematic review of studies analyzing the miRNA expression profile of peripheral blood and mononuclear cells for patients with MG.

METHODS

We ran a database search in PubMed, Scopus, and Web of Science on August 17, 2021. Original articles that analyzed miRNA profiles in peripheral blood (serum, plasma, and whole blood) and peripheral blood mononuclear cells (PBMCs) for patients with MG in comparison with a non-MG or healthy control (HC) group were eligible. The quality of studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2).

RESULTS

26 studies were included. The quality of studies was fair (median score, 5). Among 226 different miRNAs that were deregulated in at least one study (range, 1-87), ten miRNAs were significantly deregulated in three or more studies. Five miRNAs (50%) showed the same deregulation: miR-106b-3p and miR-21-5p were consistently upregulated, and miR-20b, miR-15b, and miR-16 were consistently downregulated. Also, there were five miRNAs that were mostly upregulated, miR-150-5p, miR-146a, miR-30e-5p, and miR-338-3p, or downregulated, miR-324-3p, across studies.

CONCLUSION

These miRNAs contribute to different pathways, importantly neural apoptosis and autophagy, inflammation, T regulatory cell development, and T helper cell balance. Prior to being used for diagnostic and therapeutic purposes, it is required to pursue molecular mechanisms these consistently and mostly dysregulated miRNAs specifically use in the context of MG.

Haemolysis Detection in MicroRNA-Seq from Clinical Plasma Samples

The abundance of cell-free microRNA (miRNA) has been measured in blood plasma and proposed as a source of novel, minimally invasive biomarkers for several diseases. Despite improvements in quantification methods, there is no consensus regarding how haemolysis affects plasma miRNA content. We propose a method for haemolysis detection in miRNA high-throughput sequencing (HTS) data from libraries prepared using human plasma. To establish a miRNA haemolysis signature we tested differential miRNA abundance between plasma samples with known haemolysis status. Using these miRNAs with statistically significant higher abundance in our haemolysed group, we further refined the set to reveal high-confidence haemolysis association. Given our specific context, i.e., women of reproductive age, we also tested for significant differences between pregnant and non-pregnant groups. We report a novel 20-miRNA signature used to identify the presence of haemolysis in silico in HTS miRNA-sequencing data. Further, we validated the signature set using firstly an all-male cohort (prostate cancer) and secondly a mixed male and female cohort (radiographic knee osteoarthritis). Conclusion: Given the potential for haemolysis contamination, we recommend that assays for haemolysis detection become standard pre-analytical practice and provide here a simple method for haemolysis detection.

Long Non-Coding RNAs in the Cell Fate Determination of Neoplastic Thymic Epithelial Cells

Thymic Epithelial Tumors (TETs) arise from epithelial cells of the thymus and are very rare neoplasms comprising Thymoma, Thymic carcinoma, and Thymic Neuroendocrine tumors that still require in-depth molecular characterization. Long non-coding RNAs (lncRNAs) are emerging as relevant gene expression modulators involved in the deregulation of several networks in almost all types of human cancer, including TETs. LncRNAs act at different control levels in the regulation of gene expression, from transcription to translation, and modulate several pathways relevant to cell fate determination under normal and pathological conditions. The activity of lncRNAs is strongly dependent on their expression, localization, and post-transcriptional modifications. Starting from our recently published studies, this review focuses on the involvement of lncRNAs in the acquisition of malignant traits by neoplastic thymic epithelial cells, and describes the possible use of these molecules as targets for the design of novel therapeutic approaches specific for TET. Furthermore, the involvement of lncRNAs in myasthenia gravis (MG)-related thymoma, which is still under investigation, is discussed.

A Review on the Role of Non-Coding RNAs in the Pathogenesis of Myasthenia Gravis

Myasthenia gravis (MG) is an autoimmune condition related to autoantibodies against certain proteins in the postsynaptic membranes in the neuromuscular junction. This disorder has a multifactorial inheritance. The connection between environmental and genetic factors can be established by epigenetic factors, such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). XLOC_003810, SNHG16, IFNG-AS1, and MALAT-1 are among the lncRNAs with a possible role in the pathoetiology of MG. Moreover, miR-150-5p, miR-155, miR-146a-5p, miR-20b, miR-21-5p, miR-126, let-7a-5p, and let-7f-5p are among miRNAs whose roles in the pathogenesis of MG has been assessed. In the current review, we summarize the impact of miRNAs and lncRNAs in the development or progression of MG.

MicroRNA regulation of B cell receptor signaling

B lymphocytes play a central role in host immune defense. B cell receptor (BCR) signaling regulates survival, proliferation, and differentiation of B lymphocytes. Signaling through the BCR signalosome is a multi-component cascade that is tightly regulated and is important in the coordination of B cell differentiation and function. At different stages of development, B cells that have BCRs recognizing self are eliminated to prevent autoimmunity. microRNAs (miRNAs) are small single-stranded non-coding RNAs that contribute to post-transcriptional regulation of gene expression and have been shown to orchestrate cell fate decisions through the regulation of lineage-specific transcriptional profiles. Studies have identified miRNAs to be crucial for B cell development in the bone marrow and their subsequent population of the peripheral immune system. In this review, we focus on the role of miRNAs in the regulation of BCR signaling as it pertains to B lymphocyte development and function. In particular, we discuss the most recent studies describing the role of miRNAs in the regulation of both early B cell development and peripheral B cell responses and examine the ways by which miRNAs regulate signal downstream of B cell antigen receptor to prevent aberrant activation and autoimmunity.

Role of miRNAs in Normal and Myasthenia Gravis Thymus

The thymus, a primary lymphoid organ, provides a complex environment essential for the generation of the T-cell repertoire. Thymic alterations occur during life either in the context of thymic involution upon aging or the pathophysiological context of Myasthenia Gravis (MG). These changes involve complicated regulatory networks, in which microRNAs (miRNAs) are key players. Here, we analyzed the role of miRNAs in thymocyte maturation and differentiation sustained by thymic epithelial cells. We compared data from the literature regarding the role of mouse thymic miRNAs and original data obtained from a human thymic miRnome study. We identified a set of highly expressed miRNAs defined as ThymiRs and investigated miRNA expression in infants as compared to adults to determine those associated with human thymic involution. Thymic changes are also frequently observed in MG, an autoimmune disease which results in the production of anti-acetylcholine receptor (AChR) antibodies that lead to muscle weaknesses. Alterations such as thymoma in late-onset MG patients and hyperplasia with ectopic germinal centers (GCs) in early-onset (EOMG) patients are found. Thymic miRNA expression has been studied in AChR-MG patients both in thymoma-associated MG (TAMG) and EOMG, and their function through their mRNA targets investigated. Most of the dysregulated thymic miRNAs in EOMG are associated with GC development, such as miR-7, miR-24, miR-139, miR-143, miR-145, miR-146, miR-150, miR-452, miR-548 or thymic inflammation, such as miR-125b, miR-146, or miR-29. Understanding these pathways may provide therapeutic targets or biomarkers of disease manifestations.

Emerging Roles of Dysregulated MicroRNAs in Myasthenia Gravis

Myasthenia gravis (MG) is a rare acquired autoimmune neuromuscular disease. Autoantibodies, cellular immunity, complement, and cytokines are involved in the pathogenesis of MG. It is characterized by the dysfunction of neuromuscular junction transmission and skeletal muscle weakness. MicroRNAs (miRNAs) are non-coding small molecule ribonucleic acids that regulate various biological processes (e.g., development, differentiation, and immunity) at the transcriptional and post-transcriptional levels of gene expression. miRNAs play an important regulatory role in the pathogenesis of autoimmune diseases, including MG. In recent studies, the functional mechanisms underlying the role of miRNAs in the pathogenesis of MG have received increasing attention. miRNAs are highly stable and have high specificity in peripheral body fluids. Therefore, the miRNAs in body fluids may represent promising biomarkers for determining the prognosis of MG and the efficacy of treatment. This article reviews the role of miRNAs in the pathogenesis of MG, highlights the potential of miRNAs as new biomarkers for the diagnosis of MG, and deepens our understanding of disease processes.

Circulating miRNAs as Potential Biomarkers in Myasthenia Gravis: Tools for Personalized Medicine

Myasthenia gravis (MG) is an autoimmune disease caused by antibodies which attack receptors at the neuromuscular junction. One of the main difficulties in predicting the clinical course of MG is the heterogeneity of the disease, where disease progression differs greatly depending on the subgroup that the patient is classified into. MG subgroups are classified according to: age of onset [early-onset MG (EOMG; onset ≤ 50 years) versus late-onset MG (LOMG; onset > 50 years]; the presence of a thymoma (thymoma-associated MG); antibody subtype [acetylcholine receptor antibody seropositive (AChR+) and muscle-specific tyrosine kinase antibody seropositive (MuSK+)]; as well as clinical subtypes (ocular versus generalized MG). The diagnostic tests for MG, such as antibody titers, neurophysiological tests, and objective clinical fatigue score, do not necessarily reflect disease progression. Hence, there is a great need for reliable objective biomarkers in MG to follow the disease course as well as the individualized response to therapy toward personalized medicine. In this regard, circulating microRNAs (miRNAs) have emerged as promising potential biomarkers due to their accessibility in body fluids and unique profiles in different diseases, including autoimmune disorders. Several studies on circulating miRNAs in MG subtypes have revealed specific miRNA profiles in patients’ sera. In generalized AChR+ EOMG, miR-150-5p and miR-21-5p are the most elevated miRNAs, with lower levels observed upon treatment with immunosuppression and thymectomy. In AChR+ generalized LOMG, the miR-150-5p, miR-21-5p, and miR-30e-5p levels are elevated and decrease in accordance with the clinical response after immunosuppression. In ocular MG, higher levels of miR-30e-5p discriminate patients who will later generalize from those remaining ocular. In contrast, in MuSK+ MG, the levels of the let-7 miRNA family members are elevated. Studies of circulating miRNA profiles in Lrp4 or agrin antibody-seropositive MG are still lacking. This review summarizes the present knowledge of circulating miRNAs in different subgroups of MG.

miRNAs as Biomarkers in Disease: Latest Findings Regarding Their Role in Diagnosis and Prognosis

MicroRNAs (miRNAs) represent a class of small, non-coding RNAs with the main roles of regulating mRNA through its degradation and adjusting protein levels. In recent years, extraordinary progress has been made in terms of identifying the origin and exact functions of miRNA, focusing on their potential use in both the research and the clinical field. This review aims at improving the current understanding of these molecules and their applicability in the medical field. A thorough analysis of the literature consulting resources available in online databases such as NCBI, PubMed, Medline, ScienceDirect, and UpToDate was performed. There is promising evidence that in spite of the lack of standardized protocols regarding the use of miRNAs in current clinical practice, they constitute a reliable tool for future use. These molecules meet most of the required criteria for being an ideal biomarker, such as accessibility, high specificity, and sensitivity. Despite present limitations, miRNAs as biomarkers for various conditions remain an impressive research field. As current techniques evolve, we anticipate that miRNAs will become a routine approach in the development of personalized patient profiles, thus permitting more specific therapeutic interventions.

miR-30e-5p as predictor of generalization in ocular myasthenia gravis

Objective

To determine a predictive factor for the risk of conversion from ocular myasthenia gravis (OMG) to generalized MG (GMG) in a prospective study.

Methods

RNA was isolated from serum samples and detection of microRNA (miRNA) expression analyzed with qPCR. In the discovery set, 179 human miRNAs were assayed for profiling of five OMG patients and four age‐ and gender‐matched healthy controls. Based on the specific accumulation pattern of 19 miRNAs from the discovery set, in addition to miRNAs previously found elevated in generalized MG (GMG; miR‐150‐5p and miR‐30e‐5p), 21 miRNAs were subsequently analyzed in a validation cohort of 83 OMG patients (82 immunosuppression treatment naive; 49 male) within 3 months of diagnosis and at a follow‐up visit (median duration 28 months from first visit).

Results

Thirteen patients generalized 14.8 ± 12.0 months after the diagnosis and the majority (85%) belonged to the late onset MG group. Two miRNAs were significantly higher in secondary GMG (SGMG) patients compared to OMG patients with late onset MG: miR‐30e‐5p (9.1 ± 0.5 vs. 6.3 ± 0.9; P < 0.0001) and miR‐150‐5p (7.4 ± 1.1 vs. 6.4 ± 1.1; P = 0.01). The sensitivity for miR‐30e‐5p in differentiating OMG and SGMG was 96% in all OMG patients and 100% in late onset OMG patients.

Interpretation

This is the first study to describe a potential predictive factor associated with the risk of generalization for patients with OMG. Raised levels (>8) of miR‐30e‐5p at initial presentation in patients with ocular MG symptoms, give a predictive cut‐off for subsequent generalization of 96–100%.

Circulating microRNA plasma profile in MuSK+ myasthenia gravis

Muscle-specific tyrosine kinase antibody positive myasthenia gravis (MuSK+ MG) is an immunological subtype with distinctive pathogenic mechanisms and clinical features. The aim of this study was to analyze the circulating plasma microRNA profile of patients with MuSK+ MG. From the discovery cohort miR-210-3p, miR-324-3p and miR-328-3p were further analyzed in the validation cohort. We found a distinct plasma profile of miR-210-3p and miR-324-3p that were significantly decreased in MuSK+ MG patients compared to healthy controls (4.1 ± 1.4 vs 5.1 ± 1.4, p = .006 and 4.7 ± 1.0 vs 5.4 ± 1.3, p = .02). These findings reveal a distinct plasma miRNA profile in MuSK+ MG.

MicroRNA and mRNA expression associated with ectopic germinal centers in thymus of myasthenia gravis

BACKGROUND

A characteristic pathology of early onset myasthenia gravis is thymic hyperplasia with ectopic germinal centers (GC). However, the mechanisms that trigger and maintain thymic hyperplasia are poorly characterized. Dysregulation of small, non-coding microRNAs (miRNAs) and their target genes has been identified in the pathology of several autoimmune diseases. We assessed the miRNA and mRNA profiles of the MG thymus and have investigated their role in GC formation and maintenance.

METHODS

MG thymus samples were assessed by histology and grouped based upon the appearance of GC; GC positive and GC negative. A systems biology approach was used to study the differences between the groups. Our study included miRNA and mRNA profiling, quantitative real-time PCR validation, miRNA target identification, pathway analysis, miRNA-mRNA reciprocal expression pairing and interaction.

RESULTS

Thirty-eight mature miRNAs and forty-six annotated mRNA transcripts were differentially expressed between the two groups (>1.5 fold change, ANOVA p<0.05). The miRNAs were found to be involved in immune response pathways and identified in other autoimmune diseases. The cellular and molecular functions of the mRNAs showed involvement in cell death and cell survival, cellular proliferation, cytokine signaling and extra-cellular matrix reorganization. Eleven miRNA and mRNA pairs were reciprocally regulated. The Regulator of G protein Signalling 13 (RGS13), known to be involved in GC regulation, was identified in specimens with GC and was paired with downregulation of miR-452-5p and miR-139-5p. MiRNA target sites were validated by dual luciferase assay. Transfection of miRNA mimics led to down regulation of RGS13 expression in Raji cells.

CONCLUSION

Our study indicates a distinct miRNA and mRNA expression pattern in ectopic GC in MG thymus. These miRNAs and mRNAs are involved in regulatory pathways common to inflammation and immune response, cell cycle regulation and anti-apoptotic pathways suggesting their involvement in support of GC formation in the thymus. We demonstrate for the first time that miR-139-5p and miR-452-5p negatively regulate RGS13 expression.

Circulating microRNAs as potential biomarkers in myasthenia gravis patients

MicroRNAs (miRNAs) are small noncoding RNA molecules that bind to specific mRNA targets and regulate a wide range of important biological processes within cells. Circulating miRNAs are released into the extracellular space and can be measured in most biofluids, including blood serum and plasma. Recently, circulating miRNAs have emerged as easily accessible markers in various body fluids with different profiles and quantities specific for different human disorders, including autoimmune diseases. In myasthenia gravis (MG), diagnostic tests such as titers of serum autoantibodies specific for either the acetylcholine receptor (AChR⁺ ) or muscle-specific tyrosine kinase (MuSK⁺ ) do not necessarily reflect disease progression, and there is a great need for reliable objective biomarkers to monitor the disease course and therapeutic response. Recent studies in AChR⁺ MG revealed elevated levels of the immuno-miRNAs miR-150-5p and miR-21-5p. Of particular importance, levels of miR-150-5p were lower in immunosuppressed patients and in patients with clinical improvement following thymectomy. In MuSK⁺ MG, another profile of circulating miRNAs was found, including upregulation of the let-7 family of miRNAs. Here, we summarize the potential role of circulating miRNAs as biomarkers in general and in MG, and highlight important considerations for the analysis of circulating miRNA.

Expression and Regulatory Network Analysis of miR-140-3p, a New Potential Serum Biomarker for Autism Spectrum Disorder

Given its prevalence and social impact, Autism Spectrum Disorder (ASD) is drawing much interest. Molecular basis of ASD is heterogeneous and only partially known. Many factors, including disorders comorbid with ASD, like TS (Tourette Syndrome), complicate ASD behavior-based diagnosis and make it vulnerable to bias. To further investigate ASD etiology and to identify potential biomarkers to support its precise diagnosis, we used TaqMan Low Density Array technology to profile serum miRNAs from ASD, TS, and TS+ASD patients, and unaffected controls (NCs). Through validation assays in 30 ASD, 24 TS, and 25 TS+ASD patients and 25 NCs, we demonstrated that miR-140-3p is upregulated in ASD vs.: NC, TS, and TS+ASD (Tukey's test, p-values = 0.03, = 0.01, < 0.0001, respectively). ΔCt values for miR-140-3p and YGTSS (Yale Global Tic Severity Scale) scores are positively correlated (Spearman r = 0.33; Benjamini-Hochberg p = 0.008) and show a linear relationship (p = 0.002). Network functional analysis showed that nodes controlled by miR-140-3p, especially CD38 and NRIP1 which are its validated targets, are involved in processes convergingly dysregulated in ASD, such as synaptic plasticity, immune response, and chromatin binding. Biomarker analysis proved that serum miR-140-3p can discriminate among: (1) ASD and NC (Area under the ROC curve, AUC: 0.70; sensitivity: 63.33%; specificity: 68%); (2) ASD and TS (AUC: 0.72; sensitivity: 66.66%; specificity: 70.83%); (3) ASD and TS+ASD (AUC: 0.78; sensitivity: 73.33%; specificity: 76%). Characterization of miR-140-3p network would contribute to further clarify ASD etiology. Serum miR-140-3p could represent a potential non-invasive biomarker for ASD, easy to test through liquid biopsy.

Exome sequencing identifies targets in the treatment-resistant ophthalmoplegic subphenotype of myasthenia gravis

Treatment-resistant ophthalmoplegia (OP-MG) is not uncommon in individuals with African genetic ancestry and myasthenia gravis (MG). To identify OP-MG susceptibility genes, extended whole exome sequencing was performed using extreme phenotype sampling (11 OP-MG vs 4 control-MG) all with acetylcholine receptor-antibody positive MG. This approach identified 356 variants that were twice as frequent in OP-MG compared to control-MG individuals. After performing probability test estimates and filtering variants according to those 'suggestive' of association with OP-MG (p < 0.05), only three variants remained which were expressed in extraocular muscles. Validation in 25 OP-MG and 50 control-MG cases supported the association of DDX17_delG (p = 0.014) and SPTLC3_insACAC (p = 0.055) with OP-MG, but ST8SIA1_delCCC could not be verified by Sanger sequencing. A parallel approach, using a semantic model informed by current knowledge of MG-pathways, identified an African-specific interleukin-6 receptor (IL6R) variant, IL6R c.*3043 T>C, that was more frequent in OP-MG compared to control-MG cases (p = 0.069) and population controls (p = 0.043). A weighted genetic risk score, derived from the odds ratios of association of these variants with OP-MG, correlated with the OP-MG phenotype as opposed to control MG. This unbiased approach implicates several potentially functional gene variants in the gangliosphingolipid and myogenesis pathways in the development of the OP-MG subphenotype.

MiR-15a contributes abnormal immune response in myasthenia gravis by targeting CXCL10

MiR-15a is likely to be associated with autoimmunity. Here, we aimed to examine the expression of miR-15 cluster in PBMCs from myasthenia gravis (MG) patients and investigate the potential roles of miR-15a in MG. We found that the expression of all miR-15 cluster was decreased in MG, furthermore, miR-15a levels in ocular MG (oMG) were much lower, while CXCL10 production was increased in MG. We display that CXCL10 was a functional target gene of miR-15a in MG. Increasing miR-15a expression could reduce CXCL10 expression and alleviate the abnormal T cells activation in immune response, while decreasing miR-15a expression could activate immune response abnormally. Moreover, miR-15a expression was significantly decreased after stimulation, and prednisone treatment could upregulate miR-15a expression in steroid-responsive MG patients. Take together, our data suggest that decreased miR-15a expression facilitates proinflammatory cytokines production and contributes to immune response at least in part via regulating CXCL10 expression in MG.

Disease specific enrichment of circulating let-7 family microRNA in MuSK+ myasthenia gravis

Myasthenia gravis (MG) patients with antibodies against the muscle specific tyrosine kinase (MuSK+) have predominantly involvement of cranio-bulbar muscles and do not display thymus pathology, as do acetylcholine receptor antibody seropositive (AChR+) MG patients. In search of novel biomarkers for MuSK+ MG, we evaluated circulating serum microRNAs. Four analyzed microRNAs were specifically elevated in MuSK+ MG patient serum samples: let-7a-5p, let-7f-5p, miR-151a-3p and miR-423-5p. The circulating microRNA profile in MuSK+ MG differs from the profile previously observed in the serum of AChR+ MG, thus indicating the etiological difference between these two entities. We propose that the identified microRNAs could serve as potential serum biomarkers for MuSK+ MG.

miR-15b is Downregulated in Myasthenia Gravis Patients and Directly Regulates the Expression of Interleukin-15 (IL-15) in Experimental Myasthenia Gravis Mice

Background

miR-15b is significantly and consistently downregulated in different clinical phenotypes of myasthenia gravis (MG). However, its role in pathogenesis of MG is still not clear. This study aimed to explore the function of miR-15b in MG.

Material/Methods

Blood samples from early-onset MG, late-onset MG, thymoma patients, and healthy participants were collected. The expression pattern of IL-15 and miR-15b was identified by qRT-PCR and ELISA in patient serum and mouse tissue samples. The regulative role of miR-15b on IL-15 expression was verified in an experimental autoimmune myasthenia gravis (EAMG) mice model.

Results

qRT-PCR and ELISA showed that miR-15b expression was significantly lower and IL-15 expression was significantly higher in all EMG, LMG, and thymoma cases compared to healthy controls. Based on mouse model, we confirmed that miR-15b knockdown could increase IL-15 expression in healthy mice, while miR-15b overexpression could inhibit IL-15 expression in EAMG mice. Through searching in bioinformatics databases, we identified a highly conserved consequential pairing between IL-15 and miR-15b. Subsequent dual luciferase assay further verified this match.

Conclusions

This study is the first to report the miR-15b-IL-15 axis can directly regulate IL15 expression, which helps to further explain the abnormal IL-15 expression in MG patients and the pathogenesis of MG.

Disease specific signature of circulating miR-150-5p and miR-21-5p in myasthenia gravis patients

PURPOSE

Reliable biological markers for patients with the autoimmune neuromuscular disorder myasthenia gravis (MG) are lacking. We determined whether levels of the circulating immuno-microRNAs miR-150-5p and miR-21-5p were elevated in sera from clinically heterogeneous MG patients, with and without immunosuppression, as compared to healthy controls and patients with other autoimmune disorders.

METHODS

Sera from 71 MG patients and 55 healthy controls (HC) were analyzed for the expression levels of miR-150-5p and miR-21-5p with qRT-PCR. Sera were also assayed from 23 patients with other autoimmune disorders (AID; psoriasis, Addison's and Crohn's diseases).

RESULTS

34 MG patients had no immunosuppressive drug treatment (MG-0) and 37 patients were under stable immunosuppressive drug treatment since ≥ 6 months (MG+IMM). Serum levels of miR-150-5p and miR-21-5p were higher in the MG-0 patients compared to HC (p<0.0001). Further, miR-150-5p levels were 41% lower and miR-21-5p levels were 25% lower in the MG+IMM compared to MG-0 (p=0.0051 and 0.0419). In the AID patients, mean miR-150-5p and miR-21-5p were comparable with healthy controls (p=0.66).

CONCLUSIONS

The immuno-microRNAs miR-150-5p and miR-21-5p show a disease specific signature, which suggests these microRNAs as possible biological autoimmune markers of MG.

Detecting key genes regulated by miRNAs in dysfunctional crosstalk pathway of myasthenia gravis

Myasthenia gravis (MG) is a neuromuscular autoimmune disorder resulting from autoantibodies attacking components of the neuromuscular junction. Recent studies have implicated the aberrant expression of microRNAs (miRNAs) in the pathogenesis of MG; however, the underlying mechanisms remain largely unknown. This study aimed to identify key genes regulated by miRNAs in MG. Six dysregulated pathways were identified through differentially expressed miRNAs and mRNAs in MG, and significant crosstalk was detected between five of these. Notably, crosstalk between the "synaptic long-term potentiation" pathway and four others was mediated by five genes involved in the MAPK signaling pathway. Furthermore, 14 key genes regulated by miRNAs were detected, of which six-MAPK1, RAF1, PGF, PDGFRA, EP300, and PPP1CC-mediated interactions between the dysregulated pathways. MAPK1 and RAF1 were responsible for most of this crosstalk (80%), likely reflecting their central roles in MG pathogenesis. In addition, most key genes were enriched in immune-related local areas that were strongly disordered in MG. These results provide new insight into the pathogenesis of MG and offer new potential targets for therapeutic intervention.

New evidence of replication of hepatitis C virus in short-term peripheral blood mononuclear cell cultures

BACKGROUND

Even though hepatocytes are the main site for hepatitis C virus (HCV) replication, peripheral blood mononuclear cells (PBMC) have also been proposed as a suitable site for HCV replication. However, this issue still remains under discussion. We have previously developed an innovative system where HCV-RNA can be recovered during PBMC culture from HCV infected patients. Thus, the aim of this work was to use this novel approach in order to observe the evolution and replication of HCV genotype 1b in the PBMC of an HIV-HCV coinfected patient.

METHODS

HCV-RNA was extracted from serum, uncultured PBMC and PBMC culture at day 6, 20 and 33. The evolutionary analysis was performed using the direct sequences of three viral regions: 5'UTR, E2 and NS5A. Additionally, E2 region was cloned in order to extend the evolutive analysis.

RESULTS

In the present work, the molecular characterization of HCV along the culture showed a clear dynamic evolving process with the appearance of several nucleotide or amino acid changes in the three regions analyzed. Furthermore, the population analysis of E2 clones showed emerging and loss of lineages which indicate the fast evolutive dynamics of this system.

CONCLUSIONS

Since evolution can take place only if the virus is replicating in the culture, this finding constitutes an important evidence of viral replication in PBMC. Moreover, this extrahepatic compartment could be very important due to the presence of distinctive variants that could be responsible for resistance to treatment, viral pathogenesis and other clinical implications.

Myasthenia Gravis: paradox versus paradigm in autoimmunity

Myasthenia Gravis (MG) is a paradigm of organ-specific autoimmune disease (AID). It is mediated by antibodies that target the neuromuscular junction. The purpose of this review is to place MG in the general context of autoimmunity, to summarize the common mechanisms between MG and other AIDs, and to describe the specific mechanisms of MG. We have chosen the most common organ-specific AIDs to compare with MG: type 1 diabetes mellitus (T1DM), autoimmune thyroid diseases (AITD), multiple sclerosis (MS), some systemic AIDs (systemic lupus erythematous (SLE), rheumatoid arthritis (RA), Sjogren's syndrome (SS)), as well as inflammatory diseases of the gut and liver (celiac disease (CeD), Crohn's disease (CD), and primary biliary cirrhosis (PBC)). Several features are similar between all AIDs, suggesting that common pathogenic mechanisms lead to their development. In this review, we address the predisposing factors (genetic, epigenetic, hormones, vitamin D, microbiota), the triggering components (infections, drugs) and their interactions with the immune system [1,2]. The dysregulation of the immune system is detailed and includes the role of B cells, Treg cells, Th17 and cytokines. We particularly focused on the role of TNF-α and interferon type I whose role in MG is very analogous to that in several other AIDS. The implication of AIRE, a key factor in central tolerance is also discussed. Finally, if MG is a prototype of AIDS, it has a clear specificity compared to the other AIDS, by the fact that the target organ, the muscle, is not the site of immune infiltration and B cell expansion, but exclusively that of antibody-mediated pathogenic mechanisms. By contrast, the thymus in the early onset subtype frequently undergoes tissue remodeling, resulting in the development of ectopic germinal centers surrounded by high endothelial venules (HEV), as observed in the target organs of many other AIDs.