Seropositive Myasthenia Gravis Research Articles

Visualization and characterization of complement activation in acetylcholine receptor antibody seropositive myasthenia gravis.

There are no blood biomarkers to monitor treatment effects in myasthenia gravis (MG) or studies visualizing the acetylcholine receptor (AChR) antibody-induced membrane attack complex (MAC) at the human muscle membrane. This study aimed to compare levels of complement activation products and native complement components in MG patients and healthy controls (HCs) and to model the AChR antibody-mediated attacks in human muscle cells. We assessed the complement components and activation product levels with enzyme-linked immunosorbent assay and magnetic bead-based sandwich assays in plasma and sera of 23 MG patients and matched HCs. Receiver operator characteristic (ROC) curve analysis evaluated the diagnostic accuracy. Complement levels were correlated with the myasthenia gravis composite (MGC) scores. AChR+ MG modeling in human muscle cells used sera from nine MG patients and three HCs. MG patients had significantly higher plasma levels of C3a (p < .0001), C5 (p = .0003), and soluble C5b-9 (sC5b-9; p < .0001) than HCs. The ROC curve analysis showed a clear separation between MG patients and HCs for plasma C3a (AUC = 0.9720; p < .0001) and sC5b-9 (AUC = 0.8917, p < .0001). MG patients had higher levels of plasma complement Factor I (FI; p = .0002) and lower properdin levels (p < .0001). The MGC had moderate correlations with plasma Factor B (FB), FI, and Factor H. AChR+ MG patient sera triggered the deposition of MAC and reduced AChRs. We suggest validating plasma C3a and sC5b-9 as blood biomarkers for complement activation in MG. Further, the in vitro study allowed visualization of MAC deposition after applying AChR+ MG sera on human muscle cells.

Clinical Characteristics of Double Seropositive Myasthenia Gravis.

Double seropositive myasthenia gravis (DSP-MG) has antibodies positive to both acetylcholine receptor (AChR) antibody and muscle-specific tyrosine kinase (MuSK) antibody. This study aims to delineate the clinical phenotype of DSP-MG and assess the histopathological correlation with thymoma. This is a retrospective case series conducted at a tertiary care hospital in South India between February 2018 and October 2021. We had 13 DSP-MG patients (seven females, mean age 60.77+/-14.24). The presentation was generalized in nine patients, bulbar in three, and ocular in one patient. Multi-detector computed tomography done in 11 patients showed thymoma in five and thymic hyperplasia in one. Four patients underwent thymectomy; histopathology showed Type A, B2 (n = 2), and AB thymomas. All 13 patients improved with anticholinesterases. Nine patients were administered immunosuppressants, three patients were given intravenous immunoglobulin, and a single patient underwent plasmapheresis. Our study shows that DSP-MG is more similar to the clinical phenotype of AChR-MG.

Subxiphoid thoracoscopic thymectomy in a young female with seropositive Myasthenia Gravis: A case report

Case: Myasthenia Gravis (MG) is an autoimmune disease that occurs at the neuromuscular junction and characterized by weakness of voluntary skeletal muscles which may be generalized or localized with an incidence of 4.1 to 30 cases per million person-years. MG is diagnosed clinically and by measuring the level of acetylcholine receptor antibodies, Muscle specific kinase antibodies and Low-density lipoprotein receptor related protein-4 antibodies. Patient is managed conservatively with cholinesterase inhibitor (pyridostigmine), prednisone, Mycophenolate mofetil and surgically by thymectomy. Here we present a case of a 27-year female who was known case of seropositive Myasthenia gravis for five years who underwent a novel technique of subxiphoid thymectomy.

Serum protein biomarker profile distinguishes acetylcholine receptor antibody seropositive myasthenia gravis patients from healthy controls

There is an unmet need for objective disease-specific biomarkers in the heterogeneous autoimmune neuromuscular disorder myasthenia gravis (MG). This cross-sectional study identified a signature of 23 inflammatory serum proteins with proximity extension assay (PEA) that distinguishes acetylcholine receptor antibody seropositive (AChR+) MG patients from healthy controls (HCs). CCL28, TNFSF14, 4E-BP1, transforming growth factor alpha (TGF-α), and ST1A1 ranked top biomarkers. TGF-β1 and osteoprotegerin (OPG) differed between early- and late-onset MG, whereas CXCL10, TNFSF14, CCL11, interleukin-17C (IL-17C), and TGF-α differed significantly with immunosuppressive treatment. MG patients with moderate to high disease severity had lower uPA. Previously defined MG-associated microRNAs, miR-150-5p, miR-30e-5p, and miR-21-5p, correlated inversely with ST1A1 and TNFSF14. The presented inflammatory proteins that distinguish AChR+ MG are promising serum biomarkers for validation in prospective studies to allow for molecular signatures for patient subgroup stratification and monitoring of treatment response.

Epidemiology of seropositive myasthenia gravis in Sardinia: A population-based study in the district of Sassari.

The global incidence and prevalence of myasthenia gravis (MG) range between 6-31/million and 10-37/100,000, respectively. Sardinia is a high-risk region for different immune-mediated disorders, but the epidemiology of MG remains unclear. We determined the epidemiology of MG with acetylcholine receptor (AChR)-immunoglobulin G (IgG) and muscle-specific tyrosine kinase (MuSK)-IgG in the district of Sassari (North-Western Sardinia; population, 325,288). From the laboratory of the University Hospital of Sassari (reference for AChR/MuSK-IgG testing in Sardinia since 1998) and the main neurology units in Sardinia, we retrospectively identified MG patients with (1) AChR-IgG and/or MuSK-IgG positivity by radioimmunoprecipitation assay; and (2) residency in the district of Sassari. Incidence (January 2010-December 2019) and prevalence (December 31, 2019) were calculated. A total of 202 patients were included (incident, 107; prevalent, 180). Antibody specificities were AChR (n = 187 [93%]) and MuSK (n = 15 [7%]). The crude MG incidence (95% confidence interval) was 32.6 (26.8-39.2)/million, while prevalence was 55.3 (47.7-63.9)/100,000. After age-standardization to the world population, incidence decreased to 18.4 (14.3-22.5)/million, while prevalence decreased to 31.6 (26.1-37.0)/100,000. Among incident cases, age strata (years) at MG onset were: <18 (2%), 18-49 (14%), 50-64 (21%), and ≥65 (63%). Sardinia is a high-risk region for MG, with a prevalence that exceeds the European threshold for rare disease. Identification of the environmental and genetic determinants of this risk may improve our understanding of disease pathophysiology.

Pregnancy in Seronegative Myasthenia Gravis: A Single-Center Case Series.

The course of double-seronegative myasthenia gravis (DSNMG) during and after pregnancy has not been well described. To assess the course of DSNMG during pregnancy and within 6 months postpartum. A retrospective cohort study of women with DSNMG seen in the Duke Myasthenia gravis (MG) Clinic after 2003. Review of the Duke MG Clinic Registry and electronic medical record identified 8 patients who became pregnant after MG onset; the mean age at disease onset was 17.6 (SD = 10.0) years. Increased MG symptoms were observed in the first and third trimester and, most commonly, postpartum in 6 of 18 pregnancies. Except for 1 infant who developed respiratory distress that required neonatal intensive care admission, all the newborns were healthy at birth. As in seropositive MG, increased MG symptoms during pregnancy and within 6 months postpartum is also seen in women with DSNMG.

COVID-19 and Myasthenia Gravis Exacerbation in an Elderly Patient: a Case Report

Treatment of COVID-19 in elderly patients with myasthenia gravis (MG), an autoimmune disease characterized by increased dynamic muscle weakness, is associated with a number of challenges, such as chronic immunosuppression, exacerbation of MG, and polymorbidity.We present the case of an elderly patient with generalized seropositive MG who contracted COVID-19. Aggravating factors are the patient’s age, the duration of myasthenia gravis, COVID-19, and comorbidity (chronic coronary heart disease, diffuse cardiosclerosis, atrial fibrillation, NYHA class I heart failure, hyper­tension). The patient had a favorable outcome despite the exacerbation. The patient required intravenous injections of immunoglobulin (1 mg/kg) for 2 days, non-invasive ventilatory support, and treatment of respira­tory and urogenital nosocomial infections (Pseudomonas aeruginosa and Klebsiella oxytoca).COVID-19 led to exacerbation of MG, progression of muscle weakness, development of respiratory failure, and hypoxia in an elderly patient. Intravenous immunoglobulin is a possible effective medication in the treatment of this comorbid pathology.During the COVID-19 pandemic patients with MG may be at greater risk of worse outcomes than healthy individuals due to an immunodeficient state associated with immunotherapy and possible respiratory and bulbar muscle weakness. The examination of patients with MG and a COVID-19 may reveal new pathogenetic patterns and change the therapeutic strategy.Knowledge of the essence of the disease, the main links of its pathogenesis, the spectrum of modern therapeutic agents, and algorithms for their use allow us to improve the quality of medical care for patients with MG. The implementation of a comprehensive multidisciplinary approach in the treatment of these patients allows us to significantly reduce the mortality rate, prolong the life of patients, and improve its quality.

N°214 - Clinical and electrophysiological markers of seropositive versus seronegative myasthenia gravis: A Tunisian cohort of 75 patients

N°214 - Clinical and electrophysiological markers of seropositive versus seronegative myasthenia gravis: A Tunisian cohort of 75 patients

Severity and antibodies profile of seropositive myasthenia gravis

Background: Myasthenia gravis (MG), an autoimmune disease, affects the neuromuscular junction. The impaired neuromuscular transmission results in fatigable muscle weakness among MG patients. Positive antibodies are found among MG patients. Aims: The main aim of this study is to evaluate the correlation of MG severity with their anti-muscle-specific kinase (MUSK) and anti-acetylcholine receptor (AChR) antibody status. Moreover, the study also identifies the correlation between the antibodies profile and the severity of a seropositive MG. Setting and Design: This retrospective cross-sectional study was conducted in the tertiary center of the western region of Saudi Arabia named King Abdullah Medical City (Makkah) over 8 years, from January 2011 to December 2019. Materials and Methods: This retrospective cross-sectional study was conducted in Saudi Arabia in King Abdullah Medical City (Makkah) over 8 years, from January 2011 to December 2019 was reviewed. Seventeen patients out of 27 MG patients came out to be seropositive. The correlation was investigated between severity and antibody status. Statistical Analysis: Data were collected in an Excel sheet, and statistical analysis was performed using SPSS 21 software. Results: The results showed that most patients (87.5%) were positive for AChR antibodies only, while others (12.5%) were positive for anti-MUSK and anti-AChR. Thymoma and crisis were observed in 100% with dual seropositivity and 21% with single seropositivity. Conclusion: The study concluded that a severely aggressive course of MG is present among patients. However, detailed clinical trial studies are required for conforming MG severity and dual seropositivity.

Povezanost mijastenije gravis i imunski-posredovanih miopatija

Introduction/Aim: Myasthenia gravis (MG) is a chronic autoimmune disease of the neuromuscular junction, characterized by muscle weakness and fatigability. Idiopathic inflammatory myopathies (IIM) are an immune-mediated group of diseases characterized by progressive painful proximal weakness of the extremities. The coexistence of these two diseases is extremely rare and so far, only about fifty cases have been reported worldwide. The aim of this study was to analyze the frequency of coexistence of IIM and patients with de novo MG. Material and Methods: The study is retrospective in nature and was conducted at the "Neurology Clinic", University Clinical Center of Serbia. It included 97 patients diagnosed with myasthenia gravis between January 1, 2014 and December 31, 2018. Results: The average age of the MG patients was 54.1±18.9 years. At the time of diagnosis, 19 (19.6%) participants had at least one of the anamnestic data observed as potential indicators for the existence of immune-mediated myopathy. Finally, one patient clinically presented with generalized seropositive (anti-AchR positive) myasthenia gravis associated with the diagnosis of antisynthetase syndrome. In addition, the main characteristics of patients with combined occurrence of de novo MG and antisynthetase syndrome are presented. Conclusion: Although the simultaneous occurrence of MG and IIM is a very rare phenomenon, we need to think about the possibility of combined occurrence of these two autoimmune diseases, with the aim of early recognition and adequate treatment, and thus a better prognosis of both diseases.

SEROPOSITIVE MYASTHENIA GRAVIS AS THE CAUSE OF MULTIPLE FAILED EXTUBATIONS AND A PROLONGED ICU STAY FOR COVID-19 PNEUMONIA: A CASE REPORT AND BRIEF LITERATURE REVIEW

SEROPOSITIVE MYASTHENIA GRAVIS AS THE CAUSE OF MULTIPLE FAILED EXTUBATIONS AND A PROLONGED ICU STAY FOR COVID-19 PNEUMONIA: A CASE REPORT AND BRIEF LITERATURE REVIEW

Clinical Characteristics and Prognosis of Anti-AChR Positive Myasthenia Gravis Combined With Anti-LRP4 or Anti-Titin Antibody.

ObjectiveThis study aimed to summarize the clinical characteristics and prognosis of patients with anti- acetylcholine receptor (AChR) positive myasthenia gravis (MG) with a combination of anti-LRP4 or Titin antibodies.MethodsA total of 188 patients with generalized MG before immunotherapy were retrospectively collected and then divided into three groups: single anti-AChR positive-MG (AChR-MG, 101 cases), anti-AChR combined with anti-low-density lipoprotein receptor-related protein four-positive MG (AChR+LRP4-MG, 29 cases), and anti-AChR combined with anti-Titin-positive MG (AChR+Titin-MG, 58 cases). Clinical manifestations, therapeutic responses to immunotherapy, and follow-up information were analyzed.ResultsOf the 188 seropositive MG patients, 29 (15.4%) were positive for both AChR and LRP4 antibodies, and 58 (30.9%) were positive for both AChR and Titin antibodies. The mean disease onset ages in the three groups were 47.41 ± 7.0, 49.81 ± 9.2, and 48.11 ± 6.5 years, respectively. AChR+LRP4-MG showed female predominance (27.6% were males and 72.4% were females), with mild overall clinical symptoms. The AChR+Titin-MG group showed shorter times for conversion to generalized MG (5.14 ± 0.0 months) than the AChR-MG group (11.69 ± 0.0 months) and the AChR+LRP4-MG group (13.08 ± 0.5 months; P < 0.001 in both cases). Furthermore, AChR+Titin-MG group had increased bulbar dysfunction, higher incidences of thymoma (32.8 vs. 19.8% and 3.4%, P=0.035), more severe quantitative MG scores, as assessed by both QMG scores [15.5 (11.75–22.5) vs. 13 (8–19), P = 0.005; and 9 (6–14) P < 0.001], and MG-ADL scores [10 (8–13) vs. 8 (5–13), P = 0.018; and 6 (4–8), P < 0.001]. Treatment for AChR+Titin-MG was largely dependent on corticosteroids and immunosuppressive agents (56.7 vs. 19.2% and 16.7%, p = 0.028). The rates of achieving s(MMS) or better within 2 years following immunotherapy in the three groups were 51.5, 62.1, and 51.7%, respectively (P = 0.581).ConclusionClinical symptoms of anti-AChR positive MG combined with Titin antibody were more severe and progressed faster than those in the AChR + LRP4 and AChR groups. Regardless of antibody status, all patients responded well to immunotherapy and had relatively good prognoses.

Effects of rituximab on prognosis in myasthenia gravis: A single-center experience from Turkey

Management of treatment-resistant patients with myasthenia gravis (MG) remains an important issue. This study aimed to evaluate the effects of rituximab (RTX) treatment on the prognosis of patients with acetylcholine receptor autoantibody-positive (AChR-Ab+), muscle-specific kinase autoantibody-positive (MuSK-Ab+), or seronegative or double seropositive MG. Nineteen patients treated with RTX between 2015 and 2020 were included in this study. Demographic and clinical characteristics, prognosis, and prognostic predictors of MG were evaluated retrospectively. The Myas-thenia Gravis Foundation of America Post-Inter-vention Status (MGFA-PIS) before RTX treatment (pre-RTX) and after RTX treatment (post-RTX) were recorded. A total of 10 patients (52.6%) were AchR Ab+, 6 patients (31.6%) were MuSK Ab+, 1 patient (5.3%) was seronegative, and 2 patients (10.5%) were double seropositive. Steroid dose was pre-RTX 38.9±5.7 (25-45), it was post-RTX 10.5±10.3 (0-30) (p<0.001). Post-RTX steroid treatment was discontinued in 6 of 19 patients (p=0.041). Only three patients received intravenous immunoglobulin at the post-RTX follow-up (p<0.001). In post-RTX 12th month, the MGFA-PIS score was as minimally manifestation or better in 9 patients (47.3%) and improved or was better in 18 patients (94.7%) (p-value 0.004; <0.001, respectively). The improvement in MGFA-PIS scores post-RTX was similar in MuSK-Ab+ and AChR-Ab+ patients. The data are insufficient in seronegative and double seropositive patients and RTX must be considered in the treatment of suitable patients with MuSK-Ab+ and AChR-Ab+ refractory MG.

The prognostic value of diagnostic tools in patients with seropositive myasthenia gravis: a retrospective study of 31 cases

To confirm the diagnosis of myasthenia gravis (MG), in addition to clinical observation of the muscle weakness dynamics, pharmacological and functional tests, Computed tomography/Magnetic resonance imaging (CT/MRI) of the mediastinum, detection of antibodies to acetylcholine receptors (AChR) and to muscle specific tyrosine kinase (MuSK)/; electrophysiological tests are used: rhythmic nerve stimulation (RNS)/decrement test and electro­myography of a single muscle fiber (single-fiber EMG (SF-EMG)/jitter). The aim of our study is to determine the possible relationship between the level of antibodies to AChR and the decrement test value, to verify a correlation between SF-EMG and the severity of MG seropositive to AChR. To evaluate the effectiveness of pathogenetic treatment and prediction of the duration of remission according to the results of the study. A total of 31 patients with myasthenia gravis seropositive to AChR were examined, among whom there were 19 (61.3%) women aged 19 to 74 years. The pattern of muscle weakness was evaluated by a score of the International Clinical Classification of Severity of Myasthenia gravis scale (MGFA). The presence of respiratory failure and its degree was assessed by spirography. The number of antibodies to AChR was determined using enzyme-linked immunosorbent assay (ELISA). The criteria for inclusion in the study were the confirmed diagnosis of seropositive myasthenia gravis with an AChR antibody level of more than 0.5 nmol/L. All patients underwent electrophysiological studies. Patients were examined three times: 1) at the time of visiting the doctor (in the hospital or on an outpatient basis); 2) in 16 and 3) in 24 weeks from the start of the study. Depending on the clinical condition of the patients the following treatment was prescribed: pyridostigmine, methylprednisolone, azathioprine. Statistical analyses were performed using the statistical computing environment R (R Core Team). In the dynamics of observation, a decrease in the level of antibodies to AChR and an improvement in the condition of patients according to the MGFA classification were generally observed but no correlation was found between the severity of MG and the level of antibodies to AChR during the first visit (Kruskal-Wallis test: H (4, N=31)=2.23 p=0.69); during the second visit (Kruskal-Wallis test: H (5, N=31)=9.44 p=0.09), as well as during the third visit (Kruskal-Wallis test: H (2, N=30)=2.74 p=0.25). A correlation was found between the concentration of antibodies to AChR and a thymectomy in the clinical history (Kruskal-Wallistest: H (1, N=7)=3.153752 p=0.07): over time, the level of antibodies decreased. Decrement test deviations were detected in 23 (74.2%) of the 31 patients, SF-EMG – in 20 (95%) of 21 patients. Abnormal jitter was recorded in 100% of cases with a generalized form of myasthenia gravis. During all three visits, a correlation was determined between the highest decrement test of symptomatic muscle and MG severity according to MGFA (r=0.39; p=0.042), (r=0.35; p=0.048), (r=0.41; p=0.039); and also between the jitter value and MG severity (r=0.54; p=0.032) (r=0.35; p=0.048), (r=0.61; p=0.034 respectively). Analysis of the contingency tables using the exact Fisher test provided information on the best method of treating patients. We consider that the most effective prognostic test that may affect the choice of further treatment is SF-EMG. However, due to the difficulties of using this method in routine practice, rhythmic nerve stimulation (RNS) test in clinically weak muscles should be recommended. It is not recommended to monitor antibodies to AChR in order to predict the course of the disease, it is better to use this test only for the diagnosis of seropositive myasthenia gravis.

Description of 3 patients with myasthenia gravis and COVID-19

BackgroundThe COVID-19 pandemic presents two main concerns for patients with myasthenia gravis (MG); chronic immunosuppression may put them at greater risk, and some proposed treatments for COVID-19 could cause MG exacerbation. Case descriptionWe present three patients with generalized seropositive MG who developed COVID-19. All patients had a favorable outcome, with only one patient experiencing exacerbation. In this case, exacerbation began before COVID-19; she required ICU admission, non-invasive ventilatory support, and received hydroxychloroquine, lopinavir and ritonavir which were well tolerated. One patient received IVIG in place of scheduled plasma exchange. ConclusionOutcome was favorable in all cases despite immunosuppressive therapy, use of experimental COVID-19 medication and switching of plasma exchange for IVIG.

Coexistence of myasthenia gravis and neuromyelitis optica spectrum disorder: case report in Colombia and literature review

Myasthenia Gravis (MG) and Neuromyelitis Optica Spectrum Disorder (NMOSD) are antibody-mediated channelopathies caused by complex immunological mechanisms, which are thus associated with multiple autoimmune diseases. This paper describes the case of a Colombian male patient with a history of seropositive MG that required thymectomy. After four years, he had an Optic Neuritis event and 30 years later, due to suspected autoimmune comorbidities, further investigations were performed, confirming the coexistence of NMOSD with presence of Anti-Aquaporin 4 (AQP4) antibodies (Abs). Several reports in the literature show that the coexistence of these two pathologies is more common than expected by chance. Few cases have been reported in Latin America, which makes this report meaningful. In contrast to our case, the literature shows a higher incidence among women, but, on the other hand, it is consistent with an onset with mild or moderate MG symptoms at the clinical presentation, most of which led to thymectomy, followed by manifestations of NMOSD. Timely diagnosis and the consequent therapeutic adjustment may have a significant impact on the disability of these patients. There is a need for more reports in order to extend the statistical information and to improve the characterization of these patients, primarily in our Latin American region.

Incidence of AChR Ab-positive myasthenia gravis in Israel: A population-based study.

The incidence of myasthenia gravis (MG) has traditionally been low, ranging between 2-6/106 . Several recent epidemiological studies have reported a higher incidence. We, therefore, aimed to assess and characterize the incidence of MG in Israel. We retrospectively reviewed the records of all four laboratories that performed the acetylcholine receptor antibody (AChR Ab) test in Israel between 1994 and 2013 and documented the number of newly diagnosed seropositive MG patients each year. To assure that data indeed reflect only newly diagnosed patients, patient's names and ID numbers were screened at the Hadassah medical center database since 1978, the year when the test was first performed in Israel. In order to calculate the annual incidence of the disease, the population at risk was derived from the annual publication of the Israeli Central Bureau of Statistics. The annual incidence of MG for this time period was 13.1/106 inhabitants. The mean incidence of MG between 1994 and 2003 was 7.695/106 /y, while the mean incidence between 2004 and 2013 was 18.49/106 (P<.0001). Mean age of diagnosis between 1994 and 2003 was 56.65±0.9351, while between 2004 and 2013, it was 59.89±0.5336 (P=.0012). Male to female (M:F) incidence ratio in the years 1994-2003 and 2004-2013 was 2:3.2 and 3:1.8, respectively, reflecting increased incidence among males (P<.0001). The incidence of MG in Israel has increased significantly during the last decade, especially among males of older age. These findings may reflect an etiological role of an environmental factor, increased awareness, and increased longevity in general.

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.

Estrogen Receptor, Inflammatory, and FOXO Transcription Factors Regulate Expression of Myasthenia Gravis-Associated Circulating microRNAs.

MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate important intracellular biological processes. In myasthenia gravis (MG), a disease-specific pattern of elevated circulating miRNAs has been found, and proposed as potential biomarkers. These elevated miRNAs include miR-150-5p, miR-21-5p, and miR-30e-5p in acetylcholine receptor antibody seropositive (AChR+) MG and miR-151a-3p, miR-423-5p, let-7a-5p, and let-7f-5p in muscle-specific tyrosine kinase antibody seropositive (MuSK+) MG. In this study, we examined the regulation of each of these miRNAs using chromatin immunoprecipitation sequencing (ChIP-seq) data from the Encyclopedia of DNA Elements (ENCODE) to gain insight into the transcription factor pathways that drive their expression in MG. Our aim was to look at the transcription factors that regulate miRNAs and then validate some of those in vivo with cell lines that have sufficient expression of these transcription factors This analysis revealed several transcription factor families that regulate MG-specific miRNAs including the Forkhead box or the FOXO proteins (FoxA1, FoxA2, FoxM1, FoxP2), AP-1, interferon regulatory factors (IRF1, IRF3, IRF4), and signal transducer and activator of transcription proteins (Stat1, Stat3, Stat5a). We also found binding sites for nuclear factor of activated T-cells (NFATC1), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), early growth response factor (EGR1), and the estrogen receptor 1 (ESR1). AChR+ MG miRNAs showed a stronger overall regulation by the FOXO transcription factors, and of this group, miR-21-5p, let-7a, and let 7f were found to possess ESR1 binding sites. Using a murine macrophage cell line, we found activation of NF-κB -mediated inflammation by LPS induced expression of miR-21-5p, miR-30e-5p, miR-423-5p, let-7a, and let-7f. Pre-treatment of cells with the anti-inflammatory drugs prednisone or deflazacort attenuated induction of inflammation-induced miRNAs. Interestingly, the activation of inflammation induced packaging of the AChR+-specific miRNAs miR-21-5p and miR-30e-5p into exosomes, suggesting a possible mechanism for the elevation of these miRNAs in MG patient serum. In conclusion, our study summarizes the regulatory transcription factors that drive expression of AChR+ and MuSK+ MG-associated miRNAs. Our findings of elevated miR-21-5p and miR-30e-5p expression in immune cells upon inflammatory stimulation and the suppressive effect of corticosteroids strengthens the putative role of these miRNAs in the MG autoimmune response.

Heat shock protein 90α in thymic epithelial tumors and non-thymomatous myasthenia gravis

ABSTRACT Background Thymic epithelial tumors (TETs) are rare malignancies with unique association to the autoimmune disease myasthenia gravis (MG). Heat shock proteins (HSPs) harbor great potential as cancer biomarkers and HSP inhibitors approach clinical cancer therapy. Methods To explore HSP pathophysiology, we assessed sera (immunoassays) and tissues (immunohistochemistry) of TETs (and thymic tissues) for HSP27, phosphorylated (p)HSP27, HSP70 and HSP90α expression in 114 TETs and 26 non-thymomatous MG patients undergoing extended thymectomy. Results Serum concentrations of HSP90α were significantly increased in patients with thymic carcinomas, thymomas, thymic neuroendocrine tumors and non-thymomatous MG compared to patients who underwent thymectomy revealing regular thymic morphology or controls. In thymoma patients, high serum HSP90α represented a significantly worse prognostic factor for free-from-recurrence, and complete tumor resection led to decreased levels. The expression of HSP90 in nuclei and cytoplasm of tumor cells and non-neoplastic lymphocytes varied with WHO histological subtype. HSP90 was expressed in centroblasts of thymic germinal centers in MG patients. Higher pHSP27 serum concentrations were observed in seropositive MG and those not treated with steroids. Conclusions HSP data suggest high potential for HSPs as TET cancer biomarkers or as candidates for targeted therapy. Caution is warranted in TET patients with associated MG overexpressing HSPs.