Myasthenia gravis in a patient with chronic active hepatitis C during interferon-alpha treatment

Autoimmune Neuromuscular Diseases Induced by Immunomodulating Drugs

Immunomodulating drugs are widely used in autoimmune, transplant, and cancer patients. However, these drugs are associated with various autoimmune neuromuscular diseases such as demyelinating polyneuropathy, myasthenia gravis, and myositis. Early recognition of these complications and immediately terminating these drugs are very essential since some are life-threatening conditions. This review provides a general overview of drug-induced autoimmunity and autoimmune neuromuscular diseases associated with tumor necrosis factor alpha (TNF-α) antagonists, immune checkpoint inhibitors, and interferon (IFN) type 1 (IFN-β and IFN-α).

Myasthenia Crisis Induced by Pegylated-Interferon in Patient With Chronic Hepatitis C: A Case Report

Myasthenia gravis is occasionally associated with thymoma that needs surgical resection and may progress to severe respiratory failure. We experienced a rare case of myasthenia crisis during antiviral therapy for chronic hepatitis C, in whom mediastinal thymoma was discovered and successfully managed with surgical thymectomy and meticulous medical care.A 47-year-old-male patient complained of sudden diplopia 1 week after stopping 11-week administration of pegylated-interferon and ribavirin for chronic hepatitis C. Ophthalmologic examinations revealed ptosis on the right eyelid and restricted right eye movement. Myasthenia gravis was confirmed by positive repetitive nerve stimulation test and positive serum antiacetylcholine receptor antibody test, and mediastinal thymoma was found on chest CT scan. The ocular myasthenia gravis progressed to respiratory failure even after discontinuing antiviral treatment but eventually recovered with thymectomy, anticholinesterase administration, steroid pulse therapy, and prolonged ventilator care. We describe the clinical features of this life-threatening complication of interferon treatment along with previous myasthenia crisis cases by interferon for chronic hepatitis C.In patients with chronic hepatitis C who is going to receive interferon-based antiviral treatment, physicians need to keep in mind the potential life-threatening manifestations of myasthenia gravis before and during antiviral treatment especially when patients complain of muscular weakness and easy fatigability.

Central role of interferon-beta in thymic events leading to myasthenia gravis

The thymus plays a primary role in early-onset Myasthenia Gravis (MG) mediated by anti-acetylcholine receptor (AChR) antibodies. As we recently showed an inflammatory and anti-viral signature in MG thymuses, we investigated in detail the contribution of interferon (IFN)-I and IFN-III subtypes in thymic changes associated with MG. We showed that IFN-I and IFN-III subtypes, but especially IFN-β, induced specifically α-AChR expression in thymic epithelial cells (TECs). We also demonstrated that IFN-β increased TEC death and the uptake of TEC proteins by dendritic cells. In parallel, we showed that IFN-β increased the expression of the chemokines CXCL13 and CCL21 by TECs and lymphatic endothelial cells, respectively. These two chemokines are involved in germinal center (GC) development and overexpressed in MG thymus with follicular hyperplasia. We also demonstrated that the B-cell activating factor (BAFF), which favors autoreactive B-cells, was overexpressed by TECs in MG thymus and was also induced by IFN-β in TEC cultures. Some of IFN-β effects were down-regulated when cell cultures were treated with glucocorticoids, a treatment widely used in MG patients that decreases the number of thymic GCs. Similar changes were observed in vivo. The injections of Poly(I:C) to C57BL/6 mice triggered a thymic overexpression of IFN-β and IFN-α2 associated with increased expressions of CXCL13, CCL21, BAFF, and favored the recruitment of B cells. These changes were not observed in the thymus of IFN-I receptor KO mice injected with Poly(I:C), even if IFN-β and IFN-α2 were overexpressed. Altogether, these results demonstrate that IFN-β could play a central role in thymic events leading to MG by triggering the overexpression of α-AChR probably leading to thymic DC autosensitization, the abnormal recruitment of peripheral cells and GC formation.

Myasthenia gravis: a comprehensive review of immune dysregulation and etiological mechanisms

Autoimmune myasthenia gravis (MG) is characterized by muscle weakness caused by antibodies directed against proteins of the neuromuscular junction. The main antigenic target is the acetylcholine receptor (AChR), but the muscle Specific Kinase (MuSK) and the low-density lipoprotein receptor-related protein (LRP4) are also targets. This review summarizes the clinical and biological data available for different subgroups of patients, who are classified according to antigenic target, age of onset, and observed thymic abnormalities, such as follicular hyperplasia or thymoma. Here, we analyze in detail the role of the thymus in the physiopathology of MG and propose an explanation for the development of the thymic follicular hyperplasia that is commonly observed in young female patients with anti-AChR antibodies. The influence of the pro-inflammatory environment is discussed, particularly the role of TNF-α and Th17-related cytokines, which could explain the escape of thymic T cells from regulation and the chronic inflammation in the MG thymus. Together with this immune dysregulation, active angiogenic processes and the upregulation of chemokines could promote thymic follicular hyperplasia. MG is a multifactorial disease, and we review the etiological mechanisms that could lead to its onset. Recent global genetic analyses have highlighted potential susceptibility genes. In addition, miRNAs, which play a crucial role in immune function, have been implicated in MG by recent studies. We also discuss the role of sex hormones and the influence of environmental factors, such as the viral hypothesis. This hypothesis is supported by reports that type I interferon and molecules mimicking viral infection can induce thymic changes similar to those observed in MG patients with anti-AChR antibodies.

Pegylated interferon induced myasthenia crisis--a case report

Interferons (IFNs) have antiviral, antimitogenic, and immunostimulatory effects and are often used in the treatment of viral hepatitis and some neoplasms. Combination pegylated IFN-alpha and ribavirin therapy is currently recommended for the treatment of hepatitis C. Triple therapy, with the addition of a protease inhibitor, such as telaprevir or boceprevir, has recently become a mainstay of therapy for certain genotypes. There have also been reports outlining side effects associated with conventional IFN therapy and its immunostimulatory effects, which may cause autoimmune phenomena, including but not limited to Guillain-Barre syndrome, polymyositis, acute and chronic demyelinating polyneuropathy, and myasthenia gravis. Although a number of cases of interferon-induced myasthenia gravis have been reported, we present a case of interferon-induced myasthenia crisis that developed soon after retreatment of hepatitis C with combination interferon, ribavirin, and telaprevir.

Geoepidemiology of myasthenia gravis [corrected]

Myasthenia gravis (MG) is an autoimmune disease that affects the post-synaptic area of the neuromuscular junction. Its hallmark is weakness that worsens with activity. MG incidence is rising in the recent decades, mostly the late onset subtype, which is considered to be due to the aging population or unknown environmental factors. The disease has several subtypes which defer slightly in the clinical characteristics, immunological markers, population distribution and the suitable treatments. The autoimmune nature of the disease is manifested by a decrease in the number of acetylcholine receptors in the muscle receptors which makes the endplate potential to be lower than the threshold needed to activate muscle fiber action potential. In our review we try to find the environmental influence on the disease.

Myasthenia gravis during low-dose IFN-alpha therapy for chronic hepatitis C

We describe the case of a 56-year-old man who had high aminotransferase levels and anti-hepatitis C virus (HCV) antibodies. He underwent liver biopsy and biochemical screening to evaluate whether he would benefit from interferon (IFN) treatment. The patient was discharged with a diagnosis of HCV-related active chronic hepatitis, skin porphyria, and type 2 diabetes. On December 5, 1995, he began therapy with recombinant IFN-alpha at a dose of 3 MIU three times a week. He stopped this therapy in February 1996 because of asthenia, diplopia, headache, and anxiety. During IFN therapy, he had normal aminotransferase levels and no detectable HCV RNA, a condition that persists to the present. Between March and May 1996, the patient was admitted several times to a neurology clinic, where myasthenia gravis was diagnosed and treatment with pyridostigmine and cyclosporine was initiated. This case and others indicate that caution should be exercised in administering IFN because low doses can be correlated with myasthenia gravis in patients without malignancies.

Exacerbation of myasthenia gravis in a patient after interferon-beta treatment for chronic active hepatitis C

We report the case of a 53-year-old female patient, who developed bilateral blepharoptosis, limb weakness, dysphagia, and dyspnea several days after human natural interferon-beta (IFN-beta) treatment for chronic active hepatitis C. A positive edrophonium test, an elevated anti-acetylcholine receptor antibody titer, and decrements in the amplitude of muscle action potentials evoked by repetitive stimulation confirmed the diagnosis of myasthenia gravis (MG). Since she had been suffering from drooping of her right eyelid, fluctuating diplopia and easy fatiguability of limbs before receiving IFN-beta, her symptoms of MG were considered to be exacerbated by IFN-beta. It is recommended that IFN-beta should be used with particular care in patients with known MG or its compatible symptoms.

Myasthenia gravis: another autoimmune disease associated with hepatitis C virus infection

We report on a male Egyptian patient who developed myasthenia gravis with typical symptoms, beneficial response to pyridostigmine, and the presence of anti-acetylcholine receptor antibodies and anti-striated muscle antibodies during the course of a chronic hepatitis C infection complicated by liver cirrhosis. As also reported for the herpes simplex and for the HIV virus, hepatitis C may lead to myasthenia gravis via a mechanism of cross-reactivity between viral epitopes and the acetylcholine receptor.

Alpha interferon treatment in myasthenia gravis: effects on natural killer cell activity

The efficacy of recombinant interferon-alpha (rIFN alpha), on natural killer (NK) cell cytotoxic activity, CD3+, CD4+, CD8+, CD56+, HLA-DR+ lymphocyte counts, anti-acetylcholine receptor antibody (AChR Ab) levels, single fibre electromyography findings (SFEMG) and clinical course were evaluated in patients with myasthenia gravis (MG). During the IFN alpha treatment (3 mu, subcutaneous, 3 times a week), NK cell cytotoxicity and CD4+/8+ ratio increased, NK cell count remarkably decreased, and no significant clinical or SFEMG changes were observed. This preliminary open study in MG patients has demonstrated enhanced NK activity per unit NK cell after IFN alpha therapy. Although lymphocyte phenotypes and NK function approached normal levels during therapy, a higher dose of IFN alpha may be required for a significant clinical response. It has been also concluded that 6 months of IFN alpha therapy seems to be safe in MG, though in patients with malignancy, IFN alpha may cause increased autoimmunity, AChR positivity and MG.

Current and future therapies for myasthenia gravis

Myasthenia gravis (MG) is undoubtedly the most thoroughly understood of all human autoimmune diseases. The basic defect in the disease is a decrease in the number of available acetylcholine receptors (AChR) at neuromuscular junctions caused by an antibody-mediated autoimmune attack. Current treatments aimed at restoring the available AChR, depleting the autoantibodies or suppressing the immune system have been so effective that most patients can lead normal lives. However, prolonged drug treatment is required, and this carries a potential risk of drug toxicity and, in the case of immunosuppressants, systemic immunosuppression. The ideal treatment for MG would eliminate only the abnormal autoimmune response without interfering with the immune system. During the past 20 years, impressive advances have been made in our understanding of the immunology and molecular biology of MG. Accordingly, it should be possible to design rational and immune-based therapies in the future. In this article, we briefly review the current treatment modalities for MG, and discuss the prospects for immunotherapy.

Cytokine-induced autoimmune disorders

Cytokines are now commonly used in the treatment of many conditions, especially cancer, haematological malignancies and chronic viral hepatitis. With some of these cytokines, clinical induction and/or exacerbation of autoimmune manifestations have been observed. This has been the case with interferon-alpha and interferon-gamma, interleukin-2 and some colony-stimulating factors. All known biological and clinical autoimmune features have been observed but thyroid abnormalities have been particularly frequent. Some of these manifestations appear to be related to the effect of these exogenous cytokines on the T helper cell (TH) 1/TH2-cytokine balance and the regulatory properties of these cells. Patients with a history of underlying autoimmune disease or baseline serological abnormalities should be monitored for autoimmunity when treated with certain TH1 or TH2-inducing cytokines.