GRP78 antibodies damage the blood-brain barrier and relate to cerebellar degeneration in Lambert-Eaton myasthenic syndrome.

Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disease of the neuromuscular junction caused by autoantibodies binding to P/Q-type voltage-gated calcium channels. Breakdown of the blood-brain barrier and diffusion of cerebellar granule/Purkinje cell-reactive autoantibodies into the CNS are critical for the pathogenesis of paraneoplastic cerebellar degeneration (PCD) with Lambert-Eaton myasthenic syndrome. We recently found evidence that glucose-regulated protein 78 (GRP78) autoantibodies in the plasma of patients with neuromyelitis optica promote the CNS access of AQP4 autoantibodies. In the present study, we investigated whether the GRP78 autoantibodies in PCD-LEMS IgG boost the brain uptake of cerebellar cell-reactive antibodies across the blood-brain barrier and facilitate cerebellar dysfunction. We first evaluated the effects of purified IgG from PCD-LEMS or PCD patients on the blood-brain barrier function in human brain microvascular endothelial cells using a high content imaging system with nuclear factor κB p65 and intracellular adhesion molecule 1 (ICAM1) immunostaining. Next, we identified GRP78 autoantibodies causing blood-brain barrier permeability in PCD-LEMS IgG by co-immunoprecipitation and the living cell-based antibody binding assays. Exposure of brain microvascular endothelial cells to IgG from PCD-LEMS patients induced nuclear factor κB p65 nuclear translocation, ICAM1 upregulation, reduced claudin-5 expression, increased permeability and increased autocrine IL-1ß and IL-8 secretion; the IgG from patients with Lambert-Eaton myasthenic syndrome did not have these effects. We detected GRP78 autoantibodies in the IgG of LEMS-PCD (83.3%, n = 18), but observed fewer in patients with LEMS (6.6%, n = 15) and none were observed in the control subjects (n = 8). The depletion of GRP78 autoantibodies reduced the biological effect of LEMS-PCD IgG on brain microvascular endothelial cells. These findings suggest that GRP78 autoantibodies play a role beyond neuromyelitis optica and that they have direct implications in the phenotypic differences between PCD-LEMS and LEMS.

Distinguishing the cerebrospinal fluid cytokine profile in neuropsychiatric systemic lupus erythematosus from other autoimmune neurological diseases.

Neuropsychiatric systemic lupus erythematosus (NPSLE) is a serious complication in SLE. Although the mechanism of NPSLE remains unclear, cytokines and chemokines are considered to be involved in their pathogenesis. Here we used Bio-Plex Pro assays to examine 27 types of cytokines and chemokines in the cerebrospinal fluid (CSF) of 32 NPSLE patients. We used the CSF of 20 patients with multiple sclerosis (MS) and 22 patients with neuromyelitis optica (NMO) as a disease control group. Fourteen of 27 cytokines/chemokines were significantly higher in the NPSLE patients compared to the MS/NMO patients. We could identify six "minimum predictive markers" by using a weighted-voting algorithm that could distinguish NPSLE from MS and NMO: interleukin (IL)-17, IL-2, interferon (IFN)-γ, IL-5, basic fibroblast growth factor (FGF)-basic and IL-15. The determination of various types of CSF cytokine profiles may contribute to the diagnosis of NPSLE and may help elucidate the mechanisms underlying this disease.

Two cases of refractory polymyositis accompanied with steroid myopathy.

Polymyositis (PM) is an inflammatory muscle disease characterized by chronic inflammation in skeletal muscle. Although most patients with PM respond to corticosteroids, some cases show an unsatisfactory response and other therapeutic options must be considered. Furthermore, glucocorticosteroid (GC) toxicity leads to a significant disability known as steroid myopathy, particularly in elderly patients. Here we report two patients with refractory PM. Combined treatment with high-dose GCs, tacrolimus, and intravenous immunoglobulin resulted in beneficial effects against myositis. However, muscle weakness and the disability progressed due to steroid myopathy, and subsequent oral intake became impossible because of swallowing disturbance in these two patients. Nutritional intervention, including branched-chain amino acids (BCAAs) and rehabilitation, was undertaken in addition to treatment against myositis. These treatments finally improved the muscle weakness and activities of daily living, and the two patients were discharged after recovery. The high-dose GC treatment caused elevation of serum levels of amino acids, including BCAAs, but these amino acids subsequently declined during BCAA replacement therapy. These findings suggest that the catabolic effects of the glucocorticoid treatment impair the balance of amino acids, including BCAAs, within the muscle, leading to steroid myopathy.

Quality of life in purely ocular myasthenia in Japan.

BACKGROUND: Since there has been no conclusive evidence regarding the treatment of ocular myasthenia, treatment guidelines were recently issued by the European Federation of Neurological Societies/European Neurological Society (EFNS/ENS). However, the therapeutic outcomes concerning the quality-of-life (QOL) of patients with ocular myasthenia are not yet fully understood. METHODS: We investigated the therapeutic outcomes of patients with purely ocular myasthenia in a multicenter cross-sectional survey in Japan. To evaluate the severity of ocular symptoms, we used the ocular-quantitative MG (QMG) score advocated by Myasthenia Gravis Foundation of America. We used the Japanese translated version of the MG-QOL15, a self-appraised scoring system. RESULTS: Of 607 myasthenia gravis (MG) patients with an observation-duration of illness ≥ 2 years, the cases of 123 patients (20%) were limited to ocular muscles (purely ocular myasthenia). During the entire clinical course, 81 patients experienced both ptosis and diplopia, 36 had ptosis alone, and six had diplopia alone. Acetyl-cholinesterase inhibitors and prednisolone were used in 98 and 52 patients, respectively. Treatment improved ocular symptoms, with the mean reduction in ocular-QMG score of 2.3 ± 1.8 points. However, 47 patients (38%) failed to gain minimal manifestation or a better status. Patients with unfavorable outcomes also self-reported severe QOL impairment. Multivariate analyses showed that the pretreatment ocular-QMG score was associated with unfavorable outcomes, but not associated with the patient's QOL. CONCLUSION: A treatment strategy designed in accord with a patient's ocular presentation must be considered in order to improve ocular symptoms and the patient's QOL.

[Autoantibodies detected in acetylcholine receptor antibody-negative myasthenia gravis].

Myasthenia gravis (MG) is caused by the failure of neuromuscular transmission mediated by pathogenic autoantibodies (Abs) against the acetylcholine receptor (AChR), muscle-specific receptor tyrosine kinase (MuSK), and unknown autoantibodies. The seropositivity rates for routine AChR binding Ab and MuSK Ab in MG are 85% and a few % for MG patients in Japan, respectively. The autoimmune target in the remaining patients is unknown. In 2001, Hoch et al. reported that a proportion of AChR-Ab-negative MG patients had serum IgG antibodies against MuSK, shedding new light on the pathogenesis of the disease. This idea has been recently supported by many clinical studies, including neonatal myasthenic syndrome and animal model studies. In 2011, autoantibodies against low-density lipoprotein receptor-related protein 4(Lrp4) were identified in Japanese MG patients and, thereafter, have been reported in Germany and the USA. We developed a simple technique termed Gaussia luciferase immunoprecipitation for detecting antibodies to Lrp4. As a result, nine generalized MG patients out of 300 lacking AChR Ab were found to be positive for Lrp4 antibodies. Thymoma was not observed in any of these patients. These antibodies inhibit the binding of Lrp4 to its ligand and are predominantly of the IgG1 subclass. In other reports of Lrp4 ab, Lrp4 ab-positive sera inhibited the agrin-induced aggregation of AChRs in cultured myotubes, suggesting a pathogenic role regarding the dysfunction of the neuromuscular endplate. These results indicate that Lrp4 is the third autoantigen in patients with MG, and anti-Lrp4 autoantibodies may be pathogenic. Further studies including neuromuscular junction biopsy are needed to clarify the pathomechanism of Lrp4 ab-positive MG.

[Muscle-Specific Receptor Tyrosine Kinase Antibody Positive Myasthenia Gravis].

Reportedly, patients with muscle-specific kinase (MuSK) antibody-positive myasthenia gravis (MG) account for approximately 3.0% of all patients with MG in Japan. Compared with patients who have acetylcholine receptor antibody-positive MG, those with MuSK antibody-positive MG show young-onset disease with female predominance, a low rate of ocular involvement (5.9%), and greater severity of dysphagia. The aforementioned types of MG are indistinguishable based on clinical symptoms and electrophysiological tests, and measurement of MuSK antibodies is essential for diagnosis. Thymectomy and complement inhibitors are not indicated for treatment, and acetylcholinesterase inhibitors, steroids, immunosuppressants, plasma exchange, intravenous immunoglobulin therapy, and neonatal Fc receptor inhibitors are used.

[Diagnosis and Treatment of Lambert-Eaton Myasthenic Syndrome].

Approximately 90% of patients with Lambert-Eaton myasthenic syndrome (LEMS) show positive P/Q-type voltage-gated calcium channels antibodies, which can be broadly classified clinically as paraneoplastic, particularly with small cell lung carcinoma and non-paraneoplastic without cancer. The first Japanese guideline for LEMS was developed in May 2022 as MG/LEMS Practice Guideline 2022. This article describes the epidemiology, symptoms, diagnosis, examination, treatment, and prognosis of this condition, based on the LEMS guidelines.

Clinical, serologic and magnetic resonance imaging of 3 cases of inflammatory myopathy with abundant macrophages in the Japanese population.

We report the first 3 cases of inflammatory myopathy with abundant macrophages (IMAM) to be found in an Asian country. Diagnosis of IMAM was based on the infiltration of CD68+ macrophages into biopsied specimens, particularly the fascia. Proximal skeletal muscle symptoms and signs, elevation of creatine kinase, and myogenic changes in electromyography were found in all of the cases, and magnetic resonance imaging clearly revealed thickening of the fascia. Since dermatomyositis (DM)-specific skin alterations were not found, none of the patients in this study fulfilled Bohan and Peter's criteria for DM; however, anti-PL-7 antibody was detected in case number 1. In addition, CD20+ B-cell infiltration into the fascia was also detected in all of the cases, indicating further transition to DM. Severe illness, namely macrophage activation syndrome and acute respiratory distress syndrome, occurred in case 1 but was resolved with intensive combination therapy. The other 2 cases also required glucocorticoids to achieve remission.

[Novel autoantibodies in myasthenia gravis].

Patients with myasthenia gravis(MG) are divided into three groups: (1) acetylcholine receptor antibody positive MG: 80%, (2) muscle-specific receptor tyrosine kinase (MuSK) antibody positive MG: 5-10%, and (3) double seronegative MG. In 2011, autoantibodies (Abs) against low-density lipoprotein receptor-related protein 4(Lrp4) were identified in Japanese MG patients and thereafter have been reported in Germany and USA. In other Lrp4 Ab papers, Lrp4 Ab positive sera inhibited agrin-induced aggregation of AChRs in cultured myotubes, suggesting a pathogenic role regarding the dysfunction of the neuromuscular endplate. Anti-MuSK autoantibodies were revealed to block binding of collagen Q (ColQ) to MuSK. Anti-Kv1.4 antibodies targeting alpha-subunits(Kv1.4) of the voltage-gated potassium channel occurs frequently among MG patients with thymoma. Further understandings of neuromuscular junction structure and functions through newly discovered autoantibodies may provide more specific clinical information and treatments in MG.

[LEMS: Clinical Significance of Pathogenic Autoantibodies].

Approximately 90% of patients with Lambert-Eaton myasthenic syndrome (LEMS) are positive for P/Q-type voltage-gated calcium channels (VGCCs) antibodies, and can be broadly divided into two groups: paraneoplastic, especially with small cell lung carcinoma and, non-paraneoplastic, without cancer. Under the Japanese LEMS diagnostic criteria 2022, abnormal electrophysiological results is mandatory for diagnosis in addition to muscle weakness. Contrastingly, autoantibodies are useful for diagnosing the etiology and influence treatment strategies. We comprehensively reviewed the MG/LEMS 2022 practice guidelines. Moreover, we presented a case of PCD without LEMS that was positive for P/Q-type VGCCs antibodies_and discussed the clinical significance of the autoantibodies.

Autoantibodies to low-density lipoprotein receptor-related protein 4 in myasthenia gravis.

Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction, where acetylcholine receptor (AChR), muscle-specific kinase (MuSK), and low-density lipoprotein (LDL) receptor-related protein 4 (Lrp4) are essential. About 80% and 0% to 10% of patients with generalized MG have autoantibodies to AChR and MuSK, respectively, but pathogenic factors are elusive in others. Here we show that a proportion of AChR antibody-negative patients have autoantibodies to Lrp4. These antibodies inhibit binding of Lrp4 to its ligand and predominantly belong to the immunoglobulin G1 (IgG1) subclass, a complement activator. These findings together indicate the involvement of Lrp4 antibodies in the pathogenesis of AChR antibody-negative MG.

Antibodies against the main immunogenic region of the acetylcholine receptor correlate with disease severity in myasthenia gravis.

OBJECTIVE: We developed an assay that detects autoantibodies against the main immunogenic region (MIR) located at the extracellular end of the nicotinic acetylcholine receptor (AChR) α subunit, and investigated its clinical relevance in myasthenia gravis (MG). METHODS: In this retrospective cohort study, we measured MIR antibody (Ab) titres in sera obtained before treatment and analysed their associations with clinical parameters in 102 MG patients from two neurological centres. MIR Ab titres were determined using a modified competition immunoprecipitation assay in the presence or absence of monoclonal antibody 35. RESULTS: 11 of 23 (47.8%) ocular type and 66 of 72 (91.7%) generalised type MG patients were positive for the presence of MIR Abs, defined as a titre >16.8% (3 SDs above the mean for 70 healthy controls). A significantly higher MIR Ab titre (p<0.001) was shown in generalised type (47.9±19.2%) rather than in ocular type MG patients (16.4±8.4%). Bivariate regression analysis using both titre levels of MIR Ab and routine AChR binding Ab as variables revealed MIR Abs to be an exclusive indicator positively associated with disease severity (Myasthenia Gravis Foundation of America classification, p<0.0001; Quantitative MG score, p=0.008), the presence of bulbar symptoms (p<0.0001) and thymoma (p=0.016), and negatively associated with ocular MG (p<0.0001). CONCLUSIONS: MIR Ab titre levels show much better correlations with factors related to disease severity compared with AChR binding Ab titres. The MIR Ab assay may be useful for predicting MG symptom severity, especially for discriminating between ocular and generalised types of MG.

A case of primary Sjögren's syndrome complicated with inflammatory myopathy and interstitial lung disease.

We experienced a case of a 63-year-old woman with primary Sjögren's syndrome (pSS) complicated with inflammatory myopathy and interstitial lung disease (ILD). She had suffered from morning stiffness and dry mouth for 1 year without being medically examined. A chest CT scan demonstrated ground glass opacity and a reticular shadow in the lower lung field. A diagnosis of SS was made based on positive findings from Schirmer's test, sialography of the parotid gland, a labial salivary gland biopsy and the presence of anti-SS-A antibody. Musculoskeletal symptoms were absent; however, the elevation of creatine kinase (CK) as well as magnetic resonance imaging (MRI)-proven inflammatory change of bilateral muscles of the thigh was evident. Histological examination of the thigh revealed diameter variation, degeneration of muscle fibers and inflammatory cell infiltration in the perivascular area, corresponding to the inflammatory myopathy of pSS. Oral prednisolone 30 mg/day was introduced, and serum CK rapidly decreased within 2 weeks. ILD also responded well to prednisolone without relapse. These clinical outcomes are consistent with extraglandular organ involvement of pSS.

Two Lambert-Eaton Myasthenic Syndrome Patients with Ameliorated Activities of Daily Living Due to Cholinesterase Inhibitors.

We herein report two P/Q-type voltage-gated calcium channel (VGCC) antibody-positive Lambert-Eaton myasthenic syndrome (LEMS) patients who responded dramatically to cholinesterase inhibitors. Patient 1, a 76-year-old man, had small-cell lung cancer and developed LEMS during chemotherapy. When symptomatic treatment was started with pyridostigmine, gait disturbance was ameliorated, and his modified Rankin scale decreased from 4 points to 3 points. Patient 2, a 68-year-old man, had cancer-free LEMS. Distigmine bromide was very effective and ameliorated not only his gait disturbance but also autonomic symptoms, and his modified Rankin scale decreased from 2 points to 1 point. Cholinesterase inhibitors alone may be effective in a small portion of LEMS patients.

Motor end-plate analysis to diagnose immune-mediated myasthenia gravis in seronegative patients.

This study aimed to evaluate the diagnostic usefulness of motor end-plate (MEP) analysis along with clustered acetylcholine receptor (AChR) antibody (Ab) assays in patients with myasthenia-like symptoms but negative routine AChR and muscle-specific kinase (MuSK) Ab tests. MEP analysis of muscle biopsies of the biceps brachii was performed in 20 patients to try to differentiate between those with or without immune-mediated myasthenia gravis (MG). Using a quantitative method, complement C3 deposition and AChR densities in MEPs were examined. Independently, cell-based assays were used to detect serum clustered-AChR Abs. Only five of 20 patients had complement deposition at MEPs; four of these patients had reduced AChR densities similar to those in patients with typical AChR Ab positive MG, and distinct from those in the remaining 15 patients. Two of the four serum samples from these patients had clustered-AChR Abs. All complement-positive patients were considered as having immune-mediated MG and improved with appropriate treatments; although one patient presented with MG 3 years later, the remaining patients had other diagnoses during over 10 years of follow-up. These results suggest the usefulness of MEP analysis of muscle biopsies in diagnosing immune-mediated MG in seronegative patients with myasthenia-like symptoms but, due to the invasiveness of the muscle biopsy procedure, clustered AChR Abs should, if possible, be tested first.

Paraneoplastic Cerebellar Degeneration With P/Q-VGCC vs Yo Autoantibodies.

BACKGROUND AND OBJECTIVES: Paraneoplastic cerebellar degeneration (PCD) is characterized by a widespread loss of Purkinje cells (PCs) and may be associated with autoantibodies against intracellular antigens such as Yo or cell surface neuronal antigens such as the P/Q-type voltage-gated calcium channel (P/Q-VGCC). Although the intracellular location of the target antigen in anti-Yo-PCD supports a T cell-mediated pathology, the immune mechanisms in anti-P/Q-VGCC-PCD remain unclear. In this study, we compare neuropathologic characteristics of PCD with anti-P/Q-VGCC and anti-Yo autoantibodies in an archival autopsy cohort. METHODS: We performed neuropathology, immunohistochemistry, and multiplex immunofluorescence on formalin-fixed and paraffin-embedded brain tissue of 1 anti-P/Q-VGCC, 2 anti-Yo-PCD autopsy cases and controls. RESULTS: Anti-Yo-PCD revealed a diffuse and widespread PC loss together with microglial nodules with pSTAT1+ and CD8+granzymeB+ T cells and neuronal upregulation of major histocompatibility complex (MHC) Class I molecules. Some neurons showed a cytoplasmic immunoglobulin G (IgG) staining. In contrast, PC loss in anti-P/Q-VGCC-PCD was focal and predominantly affected the upper vermis, whereas caudal regions and lateral hemispheres were spared. Inflammation was characterized by scattered CD8+ T cells, single CD20+/CD79a+ B/plasma cells, and an IgG staining of the neuropil in the molecular layer of the cerebellar cortex and neuronal cytoplasms. No complement deposition or MHC-I upregulation was detected. Moreover, synaptophysin was reduced, and neuronal P/Q-VGCC was downregulated. In affected areas, axonal spheroids and the accumulation of amyloid precursor protein and glucose-regulated protein 78 in PCs indicate endoplasmatic reticulum stress and impairment of axonal transport. In both PCD types, calbindin expression was reduced or lost in the remaining PCs. DISCUSSION: Anti-Yo-PCD showed characteristic features of a T cell-mediated pathology, whereas this was not observed in 1 case of anti-P/Q-VGCC-PCD. Our findings support a pathogenic role of anti-P/Q-VGCC autoantibodies in causing neuronal dysfunction, probably due to altered synaptic transmission resulting in calcium dysregulation and subsequent PC death. Because disease progression may lead to irreversible PC loss, anti-P/Q-VGCC-PCD patients could benefit from early oncologic and immunologic therapies.

A case of acute sarcoid myositis treated with weekly low-dose methotrexate.

A 25-year-old man was referred to our hospital with a 2-month history of progressive proximal extremity weakness. His serum creatine kinase (CK) level was extremely elevated, and chest X-ray revealed bilateral hilar lymphadenopathy and small nodules in bilateral lung fields. Biopsy specimens obtained from muscle and lung revealed non-caseating epithelioid cell granulomas. On the basis of these findings, the patient was diagnosed with sarcoidosis and acute sarcoid myositis. Although steroid pulse therapy was administered repeatedly, the muscle symptoms did not improve, and the serum CK level remained high. We added 7.5 mg oral methotrexate once per week to oral prednisolone, and this improved both the muscle weakness and the CK level. Concurrent administration of methotrexate could be a therapeutic option for cases with acute sarcoid myositis refractory to steroid therapy.

[Standard treatment for late-onset myasthenia gravis in Japan].

Myasthenia gravis (MG) is caused by the failure of neuromuscular transmission mediated by autoantibodies against acetylcholine receptors (AChR) and muscle-specific receptor tyrosine kinase (MuSK). These seropositivity rates in AChR positive and MuSK positive MG in Japan are 80-85% and 5-10%, respectively. The incidence of late-onset MG has been increasing all over the world. A nationwide epidemiological survey in Japan also revealed that the rates of late-onset MG (onset after 50 years) had increased from 20% in 1987 to 42% in 2006. In 2010, a guideline for standard treatments in late-onset MG was published from Japanese Scoiety of Neurological Therapeutics. Based on individual experiences and the limited evidence, epidemiological characteristics of MG onset age, clinical features, and the standard treatment for late-onset patients are included in it. In this guideline summary, the ocular form was more frequent in late-onset compared to early-onset group, the indication of thymectomy in late-onset MG is less than that of early-onset MG and the combination of corticosteroids and immunosuppressive agents are recommended in order to reduce doses of corticosteroids in late-onset MG.

[A pregnant patient with anti-MuSK antibody positive myasthenia gravis and her infant with transient neonatal myasthenia gravis].

A 30-year-old healthy woman experienced speech disturbance and swallowing difficulty at two months of pregnancy. She was diagnosed as myasthenia gravis (MG) with anti-MuSK antibodies. At eight months of pregnancy, bulbar palsy, eye movement disturbance, and muscle weakness worsened unexpectedly. Plasma exchange was performed three times daily starting from the 1st day of the 37th pregnancy week (2 L/day, albumin substitution of 5%) and the patient underwent caesarean section and gave birth to the girl safely. The infant had anti-MuSK antibodies in the serum and umbilical cord blood. The infant's suckling power was weak. The infant was diagnosed as transient neonatal myasthenia gravis. There is no case where management of MG has been performed from the period of pregnancy for anti-MuSK positive patients. For the control of Anti-MuSK positive patients in addition to normal care for Anti-AChR antibodies positive patients, it is important to carefully observe symptoms caused by bulbar palsy, draw attentions on malnutrition and polyhydramnios, and perform simple plasmapheresis on regular basis without any delay.