Exacerbation of myasthenia gravis after removal of a thymoma having a membrane phenotype of suppressor T cells

Poor responses and adverse outcomes of myasthenia gravis after thymectomy: Predicting factors and immunological implications

Myasthenia gravis (MG) has been recognized as a series of heterogeneous but treatable autoimmune conditions. As one of the indispensable therapies, thymectomy can achieve favorable prognosis especially in early-onset generalized MG patients with seropositive acetylcholine receptor antibody. However, poor outcomes, including worsening or relapse of MG, postoperative myasthenic crisis and even post-thymectomy MG, are also observed in certain scenarios. The responses to thymectomy may be associated with the general characteristics of patients, disease conditions of MG, autoantibody profiles, native or ectopic thymic pathologies, surgical-related factors, pharmacotherapy and other adjuvant modalities, and the presence of comorbidities and complications. However, in addition to these variations among individuals, pathological remnants and the abnormal immunological milieu and responses potentially represent major mechanisms that underlie the detrimental neurological outcomes after thymectomy. We underscore these plausible risk factors and discuss the immunological implications therein, which may be conducive to better managing the indications for thymectomy, to avoiding modifiable risk factors of poor responses and adverse outcomes, and to developing post-thymectomy preventive and therapeutic strategies for MG.

A systematic review of paraneoplastic syndromes associated with thymoma: Treatment modalities, recurrence, and outcomes in resected cases

OBJECTIVE

Paraneoplastic syndromes associated with thymomas remain incompletely understood. The objective was to examine the association between surgically resected thymomas and paraneoplastic syndromes over the past half century.

METHODS

A primary PubMed/MEDLINE search was used to identify published articles describing paraneoplastic syndromes associated with thymomas from 1960 to 2019. A secondary search identified additional articles referenced in the articles found in the primary search. Kaplan-Meier and log-rank test were used for time-to-event data analyses.

RESULTS

From 407 articles describing 507 patients, 123 different paraneoplastic syndromes were associated with thymoma. The 5 most common paraneoplastic syndromes were myasthenia gravis, pure red cell aplasia, lichen planus, Good syndrome, and limbic encephalitis. Complete or partial resolution of paraneoplastic syndrome symptoms after surgery was noted in 76% of patients, of whom 21% had a relapse or new paraneoplastic syndrome onset after surgery. The most common adjunctive therapy associated with resolution of paraneoplastic syndrome was corticosteroids (30%). For all patients after surgery, thymoma recurrence was observed in 17% of cases, whereas recurrence of paraneoplastic syndrome was observed in 34% of cases, and both were observed in approximately 11% of cases. The 5- and 10-year overall survivals were 78% and 66%, respectively. Improved overall survival was associated with patients who had total resolution from paraneoplastic syndrome.

CONCLUSIONS

A comprehensive assessment of publications over the past half century suggests that a multimodal treatment approach that includes surgical resection of thymomas is able to achieve paraneoplastic syndrome resolution in a majority of patients. Onset of new paraneoplastic syndromes after surgery is associated with the recurrence of the first paraneoplastic syndrome, and resolution of paraneoplastic syndrome is associated with improved overall survival.

Treatment of Acquired Autoimmune Myasthenia Gravis: a Topic Review

We propose a new approach to staging the disease based on clinical and immunological response to treatment. We oppose clinical remission to immunological remission and define total clinical remission as the goal of therapy. We describe the use, side effects and indications of established therapies. Acetycholine esterase inhibitors are only a symptomatic treatment as is plasma exchange. Usefulness and limits of thymectomy, corticosteroids and immunosuppressants are described here. Their goal is to reduce the auto-immune process. Long-term hazards from these medications are described and methods to reduce their potential risks are suggested. We suggest the number of patients having life threatening complications while undergoing aggressive immunosuppression can be reduced by a systematic approach to follow-up. In the second part of this review article, adapting management to specific situations is emphasized in refractory disease, respiratory failure, neonatal and juvenile forms of the disease. The special situation of seronegative myasthenia is discussed.

Myasthenia gravis with thymoma and coexistent central hypothyroidism

Myasthenia gravis (MG) is a well-known acquired autoimmune neuromuscular disorder. Patients with MG have a higher incidence of autoimmune disease than the normal population. MG is frequently associated with autoimmune thyroid disease, the most common of which is thyrotoxicosis. Associated hypothyroidism is not common, and the central (pituitary) origin, to our knowledge, has not yet been reported. We report an MG patient with thymoma that coexisted with central hypothyroidism, the correction of which is mandatory and significant to achieve remission.

Cell-mediated immune response against titin in myasthenia gravis: evidence for the involvement of Th1 and Th2 cells

Myasthenia gravis (MG) patients may have circulating autoantibodies against titin. In this study, we have stimulated T cells from MG patients with a recombinant polypeptide containing the main immunogenic region of titin, MGT-30 (myasthenia gravis titin-30 kDa). In an ELISpot assay, MGT-30 reactive interferon (IFN)-gamma secreting cells (Th1 cells) were detected in six of 10 titin antibody positive MG patients. Such cells were not detected in any of the five titin antibody negative MG patients or in the seven blood donors. In three patients, the stimulated number of cells decreased when total remission of MG symptoms was achieved after thymectomy or following a period of intensive immunosuppressive medication. We detected MGT-30 interleukin (IL)-4 secreting cells (Th2 cells) in two of five titin antibody positive MG patients, but not in the two titin antibody negative patients or the five blood donors examined. We conclude that titin antibody positive MG patients have a combined Th1/Th2 cell mediated immunity against the muscle protein titin.

Myasthenia gravis in childhood

Clinical features, serum acetylcholine receptor antibody (AChRAb) titres and course were reviewed in a series of 25 congenital (CMG) and 30 juvenile (JMG) myasthenia gravis cases to recognize characteristics of childhood-onset myasthenia and its subgroups. The initial symptom for CMG is ptosis accompanied or followed by generalized weakness; myasthenic crises do not occur and spontaneous remissions are rare. In JMG, the distribution of weakness remains the same, but the severity fluctuates: spontaneous remissions (6 patients) and myasthenic crises (10 patients) are observed. Good response to anticholinesterase drugs is slightly more frequent in JMG (62 versus 41%). AChRAbs were present in 9/26 JMG tested, girls with onset after 11 years being more likely to be Ab-positive. Since patients with autoimmune myasthenia and a young age of onset are often seronegative, clinical features such as changing distribution of weakness, fluctuating severity, or response to treatment might be considered as supportive criteria for differentiating JMG from CMG.

Change of immunological parameters in the clinical course of a myasthenia gravis patient with chronic graft-versus-host disease

The change in immunological parameters was studied during the clinical course of a myasthenia gravis (MG) patient with chronic graft-versus-host disease (GVHD), which developed after bone marrow transplantation from an HLA-identical donor. Anti-acetylcholine receptor antibody gradually decreased in the patient treated with immunosuppressive agents, but was not detected in the donor. Lymphocyte numbers were low just before the onset of MG, increased abruptly within several days and then gradually decreased with treatment. The percentage of CD3+ and CD19+ lymphocytes was higher at onset than before, the percentage of CD4+ cells was higher at onset and gradually decreased with treatment, while CD8+ cells showed the lowest level just before onset and gradually increased during the clinical course. CD4+/CD45RA- cells also showed the highest levels at onset and a gradual decrease with treatment. Cellular, as well as humoral immune responses, might be associated with the pathogenesis of MG with chronic GVHD.

Long-term change of anti-acetylcholine receptor antibody in patients with myasthenia gravis after thymectomy

Anti-acetylcholine receptor antibody (AChR Ab) plays an important role in the pathogenesis of myasthenia gravis (MG). We investigated the change of anti-AChR Ab titer after thymectomy of 10 MG patients including five patients whose age at onset was younger than 16 years. Anti-AChR Ab titer was increased in four of six patients with remission and three of four patients without remission. Change of anti-AChR Ab titer in individual patients showed an increase occurred 1-4 years after thymectomy. It is likely that thymectomy influences immune response and induces autoreactive lymphocytes and autoantibodies.

Ocular myasthenia: a protean disorder

Ocular myasthenia is a localized form of myasthenia clinically involving only the extraocular, levator palpebrae superioris, and/or orbicularis oculi muscles. Ocular manifestations can masquerade as a variety of ocular motility disorders, including cranial nerve and gaze palsies. A history of variable and fatiguable muscle weakness suggests this diagnosis, which may be confirmed by the edrophonium (Tensilon) test and acetylcholine receptor antibody titer. Anticholinesterases, corticosteroids and other immunosuppressive agents, and other therapeutic modalities, including thymectomy and plasmapheresis, are used in treatment. As the pathophysiology of myasthenia has been elucidated in recent years, newer treatment strategies have evolved, resulting in a much more favorable prognosis than several decades ago. This review provides historical background, pathophysiology, immuno-genetics, diagnostic testing, and treatment options for ocular myasthenia, as well as a discussion of drug-induced myasthenic syndromes.

Exacerbation of myasthenia gravis after removal of thymomas

It appeared from this prospective and non-randomized study, that the removal of thymomas in myasthenia gravis (MG) patients resulted in rapid exacerbation of the clinical severity of the disease and of anti-acetylcholine receptor antibodies titres, which peaked after about 300 days and continued for up to 2 years. Long-term follow-up after thymomectomy (mean duration +/- SEM after surgery 5.5 +/- 0.8 years) showed that the immunological and clinical state observed prior to surgery was eventually restored, but long-term benefit attributable to surgery could not be demonstrated. Non-thymoma MG cases, however, exhibited post-operative amelioration in clinical course and decreasing antibodies titres, both of which were already significant one year after surgery, and additional improvement was observed at the time of long-term follow-up (mean 4.3 +/- 0.5 years). Furthermore, the prognosis for MG patients not operated on was also favourable. It is suggested that the occurrence of thymomas is linked to genetic factors and that neoplasia of the thymus may be part of immunoregulatory mechanisms with predominance of inhibition.

Antibodies to skeletal muscle in myasthenia gravis. Part 3. Relation with clinical course and therapy

Fluctuations of anti skeletal muscle antibodies (AMA) were studied in relation to clinical changes and fluctuations in anti acetylcholine receptor antibodies (a-AChR). Forty-two patients with generalized myasthenia gravis were studied in clinical and serological follow-up during several years under various conditions. Results from this study demonstrate that AMA fluctuate in strong relation to a-AChR, clinical course and immunosuppressive therapy. Thymomectomy resulted in an increase or de novo appearance of AMA in 10 of the 12 patients who did not receive immunosuppressive medication.

Clinical implementation of anti-acetylcholine receptor antibodies

A multivariate analysis of anti-acetylcholine receptor (AChR) antibodies and clinical parameters other than treatment (modified Osserman groups, age, type of onset, sex, and thymus pathology) was performed for all incident (n = 366) myasthenia gravis (MG) cases in its white population in Denmark during the past 15 years. Sera from 244 healthy individuals and from 295 patients with diseases other than MG were analysed as controls. Formal statistics for the anti-AChR antibodies assay (immunoprecipitation RIA using crude human AChR extract) were calculated. The distribution of antibodies titres greater than 0.1 nMole/l was found to be approximately lognormal. For MG patients the 95% reference interval was 0.2-1549 nMoles/l, and in control sera the range was 0.0-0.4 nMole/l. Using 0.5 nMole/l as the cut-off level and regarding all results less than this value as normal titres, it appeared that the assay was highly specific (> 99.99%) for MG. In a population of MG patients significance should be attributed to values in the range 0.3-0.4 nMole/l. The overall diagnostic sensitivity was found to be 88%. The sensitivity appeared to be proportionate to clinical severity of MG. The percentage with a normal titre was higher (16%) for early onset of MG, compared with 7% for late onset. No significant difference in relation to the frequency of "negative titre" was found in relation to sex. Anti-AChR antibodies titre was found to correlate with clinical severity, female or male gender, and pathology of thymus. The groups of MG patients were not matched for the various clinical parameters but multiple regression analysis controlling for these variables revealed independent effects of clinical severity and sex though not of age. Normal thymus (including involuted gland) and thymoma were correlated with low to intermediate tires, and hyperplastic thymus with high level of antibodies. The clinical implementation of anti-AchR antibodies is reviewed from 1976 and up to the present. The problems with false positive results are thoroughly expounded.

Myasthenia gravis

Myasthenia Gravis is a disorder of neuromuscular function resulting from an immunologically based premature destruction of acetylcholine receptors. The disease is characterized clinically by variable weakness accentuated by repetitive muscular activity and usually responding to the administration of acetylcholinesterase inhibitors. Myasthenia Gravis is a complex disease and requires understanding of the many facets of its natural history and immunological basis to ensure optimal individual patient management. The long-term goal is control of the immunological imbalance; treatment regimens include thymectomy, corticosteroids, azathioprine, and plasmapheresis. The common use of acetylcholinesterase inhibitors provides symptomatic relief during variable daily muscular activity. Disability due to myasthenia gravis is to a large extent reversible and death is preventable. Early recognition of myasthenia gravis and appropriate treatment are often rewarded by remission that may be permanent.

Immunoglobulin allotypes in myasthenia gravis patients with a thymoma

Gm and Km allotypes were examined in 29 myasthenia gravis patients with a thymoma and non-receptor skeletal muscle antibodies. The frequency of the phenotype Gm1,2,3;23;5,21 was significantly higher in the patients than in 292 healthy controls (P less than 0.01). Km allotype frequencies did not differ in patients and controls.

[Study of circulating lymphocytes by monoclonal antibodies in myasthenia gravis]

A significant decline of CD3 cell detected by rosettes and a significant increased of B cell populations were observed. The total CD3+, helper CD4+ and suppressor CD8+ T-cell subsets showed no significant variation em relation to sex, age thymectomy and corticotherapy by monoclonal antibodies.

Thymic lymphoepitheliomas and skeletal muscle expressing common antigen(s)

Rabbit antiserum to a citric acid extract of human skeletal muscle (CA) stained epithelial thymoma cells as well as skeletal muscle. Thymomas from two myasthenia gravis (MG) patients showing no circulating anti-CA antibodies prior to thymectomy were also stained by the antiserum. Thus, in these patients as well, the thymoma and skeletal muscle possess common antigens. The rabbit and the human antibodies most probably reacted with different antigens, apparently located close to each other in the cell membrane. The reason why anti-CA antibodies cannot be detected in serum from a few MG patients with a thymoma may be that the thymoma-associated antigen is not present in vivo in these cases, or that an inhibiting factor blocks the antibody synthesis. Both patients developed anti-CA antibodies post-operatively, which favours the latter explanation.

Immunohistological evidences of cortical and medullary differentiation in thymoma

The phenotypical characteristics of human epithelial and lymphoid cells have been studied with immunohistochemical methods on frozen sections of 12 thymomas. On the basis of the cytohistological characteristics of thymoma epithelial cells (EC) the thymomas were divided in cortical, medullary and mixed types, according to recently developed light microscopical criteria. When tested with a series of monoclonal antibodies, thymoma EC were all stained by the antibody Ki-M3 (as in the thymus), but reacted with anti-HLA-DR, anti-HLA-A,B,C and with a new monoclonal antibody to cortical EC, 21A6, to a lesser extent and with weaker, variable intensity in comparison with the normal thymus. Cortical type thymomas were most reactive and the medullary type almost negative. Thymomas, like normal thymus showed different immunoreactivity patterns with antibodies to prekeratins of different specificities. Cortical type thymomas and areas in mixed thymoma showed an EC staining with the antibody to non-squamous type keratin (35 beta H11) whereas medullary type thymomas and areas showed staining with antibodies to squamous-type keratin (34 beta E12-IV/82) in addition. Lymphoid cells with cortical (OKT6+, Leu 1 weakly+, Leu 2a+, Leu 3a+) or mature medullary (OKT6-, Leu 1 strongly+, Leu 2a or Leu 3a+) phenotype were found to colonize tumours with different EC types. These immunohistochemical findings largely confirm our earlier cytological distinction of thymoma EC. In addition important differences have been observed in neoplastic cortical EC concerning the HLA-DR and 21A6 immunoreactivity that may be intimately related to the neoplastic process and paraneoplastic immune phenomena.