Advances in myasthenia gravis

Silencing EPB41 Gene Expression Leads to Cell Cycle Arrest, Migration Inhibition, and Upregulation of Cell Surface Antigen in DC2.4 Cells

BACKGROUND Protein 4.1R (EPB41) is the main cytoskeleton component of the erythrocyte membrane and may be involved in cell migration and adhesion. Previous research discovered overexpression of 4.1R in the thymus of patients with myasthenia gravis (MG). The protein 4.1R on dendritic cells may play a pivotal role in MG pathogenesis. This research investigated the effects of small interfering RNA 4.1R-siRNA on cell migration, cell cycle, and surface antigen expression of DC2.4 mouse dendritic cells, thus providing a new direction for the study of MG pathogenesis. MATERIAL AND METHODS Three 4.1R-specific siRNAs were designed, and the expression of 4.1R was detected by real-time PCR at the mRNA level and Western blot analysis at the protein level to select out the most efficient siRNAs. Changes in cell morphology were observed and cell migration ability was analyzed by Transwell assay. Cell cycle and surface antigen were both analyzed by flow cytometry. RESULTS The cell bodies of DC2.4 diminished, the synapses were increased, and protuberance became more obvious after being transfected with 4.1R-siRNA. After knockdown of 4.1R, cell migration ability decreased and the proportion of cells in S phase significantly increased (both P<0.05). The expression levels of MHCII, CD80, and CD86 were all increased in DC2.4 cells (all <0.05). CONCLUSIONS Silencing the expression of 4.1R in dendritic cells resulted in inhibition of migration ability, cell cycle arrest, and increase in surface antigens, which suggest that 4.1R participates in MG autoimmunity.

Risk factors of myasthenia crisis after thymectomy among myasthenia gravis patients: A meta-analysis

BACKGROUND

The purpose of the study was to determine the risk factors of post-surgery myasthenia crisis (PMC) among myasthenia gravis (MG) patients.

METHODS

A meta-analysis to synthesize all eligible literatures was conducted to analyze PMC predictors among MG patients.

RESULTS

A total of 15 trials with 2626 patients were included for the meta-analysis. As a result, patients with history of MC (RR = 3.36, 95%CI: 2.46-4.59, P < .001), generalized MG (RR = 0.39, 95%CI: 0.26-0.59, P < .001), bulbar symptom (RR = 3.59,95%CI:2.53-5.09, P < .001), thymoma (RR = 2.10, 95%CI:1.37-3.21, P = .001), post-surgery morbidity presence(RR = 2.59, 95%CI:1.90-3.54, P < .001), high-dose pyridostigmine usage (SMD = 0.480, 95%CI: 0.35-0.61 P < .001) tended to develop PMC. Large dose of steroid may reduce the incidence of PMC (RR = 0.41 95%CI: 0.18-0.94, P = .036). Regular steroid use (P = .066), immunosuppressive therapy (P = .179), gender (P = .774), and age at thymectomy (P = .212) had no impact upon PMC development.

CONCLUSION

History of PMC, thymoma, generalized MG, bulbar symptom, and concomitant complication are the risk factors of PMC.

Sternotomy versus video-assisted thoracoscopic surgery for thymectomy of myasthenia gravis patients: A meta-analysis

INTRODUCTION

The purpose of this study was to compare thymectomy by video-assisted thoracoscopic surgery (VATS) and trans-sternal thymectomy (TS) for myasthenia gravis patients.

METHODS

A meta-analysis was conducted to compare thoracoscopic surgery and sternotomy for myasthenia gravis patients with regard to long-term effect and short-term safety.

RESULTS

A total of 23 trials were included in our research. No significant differences were detected with regard to myasthenic crisis, wound infection, and muscle weakness improvement. VATS led to less blood loss than TS (standardized mean difference, -1.233; 95% confidence interval, -1.425--1.041; P < 0.001), less risk of pulmonary infection (relative risk, 1.035; 95% confidence interval, 1.001-1.070; P = 0.043), and a shorter hospital stay. TS had a shorter operative time than VATS (standardized mean difference, 0.239; 95% confidence interval, 0.113-0.365; P < 0.001). VATS and TS achieved similar mean specimen weights and complete stable remission rates.

CONCLUSION

Based on the results of this meta-analysis of retrospective cohort studies, VATS increases surgical safety and achieves an equal surgical efficacy to TS, but TS has a shorter operative time.

Effects of thymectomy on late-onset myasthenia gravis without thymoma

OBJECTIVES

This study aims to investigate whether thymectomy is beneficial for late-onset (>50 years) myasthenia gravis patients with no thymoma, particularly for those with mild generalized weakness.

PATIENTS AND METHODS

A total of 34 patients were included in the study. The clinical course and long-term outcomes over 2 years were reviewed in 20 patients who underwent thymectomy and in 14 without thymectomy.

RESULTS

Of the 34 patients, 20 (59%) underwent thymectomy. Thymectomized patients had more severe disability at entry than non-thymectomized patients, but outcome measures did not significantly differ between the two patient groups. Moreover, subgroup analyses including 22 patients with mild generalized weakness at entry showed that the thymectomized group (n=10) showed a greater percentage of clinical remission (no symptoms; 50% versus 17%; p=0.11) and a lower frequency of the presence of generalized symptoms (30% versus 75%; p<0.05) than the non-thymectomized group (n=12) at the end of follow-up (means 9.6 years after onset).

CONCLUSIONS

Thymectomy is a potentially effective treatment for late onset, non-thymomatous patients with mild generalized myasthenia gravis.

Therapeutic options in autoimmune myasthenia gravis

Autoimmune myasthenia gravis (MG) is associated with circulating antibodies to AChR, modification of the synaptic cleft, and destruction of the postsynaptic neuromuscular membrane. The hallmark is fluctuating muscular weakness and fatigability of muscles on sustained repeated activity. Various drugs and invasive procedures have been used in the treatment of MG including acetylcholinesterase inhibitors, corticosteroids, azathioprine, cyclosporine, cyclophosphamide, mycophenolate mofetil, tacrolimus, etanercept, intravenous immunoglobulin, plasma exchange and thymectomy. We review the role of each of these drugs and invasive procedures in MG. Although current treatment is highly successful and mortality is almost nil, further trials are required to identify the most suitable treatments for different subgroups of MG patients. In addition, safer and more potent drugs are required as most current drugs have major side effects due to immunosuppression. Therefore, the goal of novel therapies should be increased specificity of the immune-directed agents.

Preoperative Preparation of the Patient with Myasthenia Gravis

All patients who are to undergo a thymectomy should be evaluated thoroughly by a neurologist--ideally one with special training and interest in the diagnosis and management of MG. Confirmatory tests to diagnose MG and other potential diseases should be reviewed. The antibody test seems to be most specific, but there are rare cases of other diseases that are ACh-R antibody positive. In 10% of MG patients, serology is negative, and other tests are necessary to confirm the diagnosis. All patients should undergo a contrast-enhanced high-resolution CT scan with 5- to 8-mm slices because thymoma or thymic carcinoma may be present. Pulmonary function tests, including vital capacity, forced expiratory volume, maximal expiratory force, arterial blood gas, and a flow-volume loop, should be performed. Exercise testing to evaluate for hypoxia and hypotension with exercise and ambulation also may be appropriate. A thorough assessment for cardiac dysfunction, including echocardiography, nuclear medicine studies, or a formal cardiology evaluation, may be beneficial. Because MG is a complex autoimmune disease, preoperative blood tests should include thyroid function testing, antinuclear antibody, and rheumatoid factor in addition to routine preoperative studies. Plasmapheresis or intravenous immunoglobulin should be considered for patients with advanced disease, bulbar symptoms, or poor pulmonary function. Given these guidelines, careful selection of candidates for surgery should optimize the long-term results for patients with MG.

Treatment and outcome of myasthenia gravis: retrospective multi-center analysis of 470 Japanese patients, 1999–2000

To clarify the current status of treatments and outcomes of patients with myasthenia gravis (MG) in Japan, a total of 470 patients (164 men and 306 women; mean age 41 years) were recruited from 19 Japanese tertiary medical centers in 1999-2000. Thymectomy was performed in 319 (68%) of the patients. Patients who received thymectomy were younger (p = 0.01) and had more severe disabilities (p < 0.01) than patients without thymectomy. Irrespective of receiving thymectomy, most of the patients were administered corticosteroids (64%), other immunosuppressive agents (10%), or cholinesterase inhibitors (86%). Of 395 patients followed up for more than 12 months after treatment (mean 8.0 years), 30% (34% of thymectomized and 21% of non-thymectomized patients) were in remission (no symptoms with/without medication), 34% had only ocular symptoms, and the remaining 35% still had weakness of bulbar or limb muscles at the end of follow-up. The prognosis of MG in Japan was generally favorable, but despite the frequent use of thymectomy and immunosuppressive treatments, approximately one-third of patients still had generalized weakness. More effective or intensive treatments are required to improve the prognosis.

Myasthenia gravis after allogeneic bone marrow transplantation treated with mycophenolate mofetil monitored by peripheral blood OX40+ CD4+ T cells

A patient who developed myasthenia gravis (MG) 25 months after allogeneic bone marrow transplant was immunologically analyzed. OX40+CD4+ T cells in the peripheral blood prominently increased one month before the onset of MG. CD4/CD8 ratios, usually abnormally inverted in patients with chronic graft-vs.-host disease (cGVHD), showed pseudonormalization during the course of MG. We succeeded in uneventful rapid tapering of prednisolone (PSL) using mycophenolate mofetil (MMF). Monitoring of OX40+CD4+ T cells supported the tapering of PSL and MMF as a marker of cGVHD activity. This case suggested the utility of MMF and monitoring of OX40+CD4+ T cells in the management of cGVHD-associated autoimmune diseases.

Paraneoplastic neurological syndromes: an update on diagnosis, pathogenesis, and therapy

Since the discovery of the first clinically relevant anti neuronal antibody specific for a paraneoplastic aetiology in 1985, the number of such reactivities has grown at a rate of about one per year. Clinicians can now diagnose a paraneoplastic syndrome much more easily. This ability is especially important because, typically, the neurological symptoms occur before the cancer is diagnosed. Early tumour diagnosis is essential, because effective treatment of the cancer still seems to be the most efficient treatment option for the neurological symptoms. Immuno modulatory therapy should, nevertheless, be initiated as early as possible and seems especially helpful for peripheral syndromes and limbic encephalitis. The recent fundamental advances in understanding of the autoimmune pathology of these disorders, especially the role of cytotoxic T cells, should eventually lead to more effective treatment options.