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

A Systematic Review of the Potential Implication of Infectious Agents in Myasthenia Gravis

Background: Myasthenia gravis (MG) is an autoimmune disorder of unknown etiology in most patients, in which autoantibodies target components of neuromuscular junctions and impair nerve to muscle transmission.

Objective: To provide a synthesis of the evidence examining infectious agents associated with the onset of MG.

Hypothesis: We hypothesized that microbes play a pathogenic role in the initiation of MG. For clinical cases, the onset of clinical signs is used as a proxy for the true onset of autoimmunity.

Methods: We searched PubMed and Web of Science. Papers captured through database searching (n = 827) were assessed, yielding a total of 42 publications meeting the inclusion and exclusion criteria. An additional 6 papers were retrieved from the reference lists of relevant articles. For each pathogen, an integrated metric of evidence (IME) value, from minus 8 to plus 8, was computed based on study design, quality of data, confidence of infectious disease diagnosis, likelihood of a causal link between the pathogen and MG, confidence of MG diagnosis, and the number of infected patients. Negative IME values corresponded to studies providing evidence against a role for microbes as triggers of MG.

Results: One hundred and sixty-nine myasthenic patients infected with 21 different pathogens were documented. Epstein-Barr virus (median = 4.71), human papillomavirus (median = 4.35), and poliovirus (median = 4.29) demonstrated the highest IME values. The total median IME was 2.63 (mean = 2.53; range −3.79–5.25), suggesting a general lack of evidence for a causal link.

Conclusions: There was a notable absence of mechanistic studies designed to answer this question directly. The question of the pathogenic contribution of microbes to MG remains open.

"Precision Medicine in Autoimmune Diseases: Fact or Fiction"

Much is said about precision medicine, but its real significance and the possibility of making it a real possibility is far from certain. Several studies in each of the autoimmune diseases have provided important insight into molecular pathways but the use of molecular studies, particularly those looking into transcriptome pathways, have seldom approached the possibility of using the data for disease stratification and then for prediction, or diagnosis. Only the type I interferon signature has been considered in the use of this signature for therapeutic purposes, particularly in the case of systemic lupus erythematosus. Here, the authors provide an update on precision medicine, what can be translated into clinical practice, and what do single-cell molecular studies provide to our knowledge in autoimmune diseases, focusing on a few examples. The main message being that we should try to move from precision medicine of established disease to preventive medicine in order to predict the development of disease.

Pathomechanisms and Clinical Implications of Myasthenic Syndromes Exacerbated and Induced by Medical Treatments

Myasthenic syndromes are typically characterized by muscle weakness and increased fatigability due to an impaired transmission at the neuromuscular junction (NMJ). Most cases are caused by acquired autoimmune conditions such as myasthenia gravis (MG), typically with antibodies against the acetylcholine receptor (AChR). Different drugs are among the major factors that may complicate pre-existing autoimmune myasthenic conditions by further impairing transmission at the NMJ. Some clinical observations are substantiated by experimental data, indicating that presynaptic, postsynaptic or more complex pathomechanisms at the NMJ may be involved, depending on the individual compound. Most robust data exist for the risks associated with some antibiotics (e.g., aminoglycosides, ketolides, fluoroquinolones) and cardiovascular medications (e.g., class Ia antiarrhythmics, beta blockers). Apart from primarily autoimmune-mediated disorders of the NMJ, de novo myasthenic manifestations may also be triggered by medical treatments that induce an autoimmune reaction. Most notably, there is growing evidence that the immune checkpoint inhibitors (ICI), a modern class of drugs to treat various malignancies, represent a relevant risk factor to develop severe and progressive medication-induced myasthenia via an immune-mediated mechanism. From a clinical perspective, it is of utmost importance for the treating physicians to be aware of such adverse treatment effects and their consequences. In this article, we aim to summarize existing evidence regarding the key molecular and immunological mechanisms as well as the clinical implications of medication-aggravated and medication-induced myasthenic syndromes.

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).

Interferon alpha: The key trigger of type 1 diabetes

IFNα is a cytokine essential to a vast array of immunologic processes. Its induction early in the innate immune response provides a priming mechanism that orchestrates numerous subsequent pathways in innate and adaptive immunity. Despite its beneficial effects in viral infections IFNα has been reported to be associated with several autoimmune diseases including autoimmune thyroid disease, systemic lupus erythematosus, rheumatoid arthritis, primary biliary cholangitis, and recently emerged as a major cytokine that triggers Type 1 Diabetes. In this review, we dissect the role of IFNα in T1D, focusing on the potential pathophysiological mechanisms involved. Evidence from human and mouse studies indicates that IFNα plays a key role in enhancing islet expression of HLA-I in patients with T1D, thereby increasing autoantigen presentation and beta cell activation of autoreactive cytotoxic CD8 T-lymphocytes. The binding of IFNα to its receptor induces the secretion of chemokines, attracting monocytes, T lymphocytes, and NK cells to the infected tissue triggering autoimmunity in susceptible individuals. Furthermore, IFNα impairs insulin production through the induction of endoplasmic reticulum stress as well as by impairing mitochondrial function. Due to its central role in the early phases of beta cell death, targeting IFNα and its pathways in genetically predisposed individuals may represent a potential novel therapeutic strategy in the very early stages of T1D.

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.

Dasabuvir (ABT333) for the treatment of chronic HCV genotype I: a new face of cure, an expert review

Hepatitis C virus (HCV) affects nearly 1.3% of US population and around 2% of people worldwide. It is associated with serious complication of Cirrhosis and Hepatocellular carcinoma leading to significant morbidity and mortality. Until now the only treatment option for this serious disease was interferon based therapy which had poor tolerance and at best SVR (Sustained virological response) in only 50% of cases. With the introduction of other direct - acting antiviral agents the treatment of HCV has been revolutionized with significantly high rates of cure. Among novel Direct acting antivirals are non-nucleoside inhibitor NS5B which is highly effective in treatment of HCV genotype 1 a and 1b including those with compensated cirrhosis achieving high cure rates with SVR more than 97 % in pooled analysis from six different phase 3 trials. This review will discuss the DAA - Dasabuvir, a non - nucleoside NS5B inhibitor, its mechanism of action, efficacy, safety & tolerance, and drug resistance. Dasabuvir is approved by FDA in combination with other DAA agents called as the 3D(Viekira Pak) in various interferon free regimens achieving high cure rates (SVR >95%) with low adverse effects. In Europe, it is approved by European medicines agency for use in combination with Ombitasvir, Paritaprevir, and ritonavir with or without ribavirin. The drug is used in treatment naive as well as previously treated patient with high success rates. It is also approved in patients with compensated cirrhosis, patients with HIV co-infection and liver transplant recipients which were in the past were excluded from treatment with interferon based therapy. Dasabuvir is extensively evaluated in large clinical trials and shown excellent SVR among HCV genotype1 patient population in combination with other oral DAAs, with good safety profile and tolerance. Its drawback is its genotype restriction, need for ribavirin (RBV) for 1a genotype, low resistance barrier and high cost. It is well tolerated with less than 1 % of patients permanently discontinuing treatment and 2% of patient experiencing a serious adverse reaction. It is contraindicated in patients with known hypersensitivity to ritonavir (e.g. Steven - Johnson syndrome) and strong inducers of CYP3A and CYP2CB.

Asunaprevir for hepatitis C: a safety evaluation

INTRODUCTION

The introduction of direct-acting antiviral (DAA) agents has revolutionized the treatment of hepatitis C virus (HCV) chronic infection. Non-structural 3 protease inhibitors are currently the most numerous class of DAAs on the market.

AREAS COVERED

This review mainly focuses on the tolerability and safety profile of asunaprevir (ASV)-containing DAA regimens. ASV is a second-wave protease inhibitor currently in Phase III clinical development in most countries and already available in Japan.

EXPERT OPINION

ASV shows potent antiviral effect and clinical efficacy on HCV genotypes 1 and 4. The all-oral combination daclatasvir/ASV reached high eradication rates in HCV genotype 1b and 4 infection, and a lower efficacy in genotype 1a infection. ASV presents a low potential for drug-drug interaction and a good tolerability as part of multiple, including all-oral, regimens. ASV is associated with a transient and usually mild increase in aminotransferase levels in a low percentage of cases. Due to the impaired pharmacokinetic profile observed in advanced liver disease, ASV use in patients with moderate or severe hepatic impairment is not allowed. In conclusion, ASV represents a powerful weapon against HCV infection and has to be considered an optimal option as a component of genotype tailored interferon-free combinations.

Interferon-free therapies for chronic hepatitis C: toward a hepatitis C virus-free world?

About 2% of the world's population is estimated to be chronically infected with hepatitis C virus (HCV). These chronic carriers are at risk of developing liver cirrhosis and its complications. Successful treatment of HCV infection is associated with improved quality of life and increased survival. Antiviral approaches were formerly based on interferon and therefore all patients with a contraindication to interferon were excluded from treatment (e.g., patients with decompensated disease, severe impairment of other organs). Very recently, interferon-free combinations have become available for genotypes 2 and 3. This review focuses on the most recently reported data on the various interferon-free combinations used (namely, sofosbuvir-based combinations, the ABT-450/ombitasvir/dasabuvir/ribavirin combination, the daclatasvir/asunaprevir combination, and the MK-5172/MK-8742 combination). All these combinations yielded amazing results in terms of efficacy (90-100%), tolerability and safety. If the problem of the high cost is overcome, interferon-free therapies will lead to what has long been a chimera, namely, an HCV-free world.

Therapeutic targeting of the inflammome

Inflammatory responses can vary depending on a myriad of factors including: (1) the initiating stimulus or trigger, (2) the cell types involved in the response, and (3) the specific effector cytokine-chemokine milieus produced. The compilation of these and other factors in a given mechanistic context is sometimes referred to as the "inflammome". Humans and other higher-order mammals have evolved (over time) several discrete inflammomes to counter the effects of pathogens. However, when these inflammomes are induced inappropriately, they drive the development of chronic inflammatory diseases. The vast majority of biological anti-inflammatory treatments currently being developed are focused on the post hoc inhibition of downstream effectors by anti-cytokine monoclonal antibodies and receptor antagonists. This prevailing "end-point treatment" has even directed a new disease classification paradigm, namely a cytokine-based disease classification, as opposed to a traditional diagnosis based on a particular tissue or organ system dysfunction. Although this approach has a number of advantages, it omits the processes that led to the generation of the inflammatory effectors in the first place. In this review, we will expand the cytokine-based disease taxonomy into an inflammome-based taxonomy that includes interventions that subvert a priori cytokine development and can complement post hoc inhibition.

GS-9669: a novel non-nucleoside inhibitor of viral polymerase for the treatment of hepatitis C virus infection

Hepatitis C virus (HCV) is an RNA virus that chronically infects 2-3% of the world's population. About 25% of these chronic carriers evolve towards liver cirrhosis, a disease that is significantly associated with reduced survival and quality of life. Antiviral therapy can eradicate the infection - a process that is associated with a reduced disease progression rate. Several oral direct agents have been developed and tested for the treatment of HCV infection. This review focuses on the mechanism of action, pharmacokinetics, efficacy, safety and resistance of GS-9669, a non-nucleoside inhibitor of viral polymerase, active against HCV genotype 1. In combination with other oral antivirals, GS-9669 results: in very high rates of viral eradication (90-100%) in patients with HCV genotype 1 infection, with a good tolerability and safety profile. In conclusion, GS-9669 is a good candidate to be used in interferon-free combinations for the treatment of chronic HCV infection.

Asunaprevir, a protease inhibitor for the treatment of hepatitis C infection

According to the World Health Organization, approximately 150 million people worldwide are chronic carriers of hepatitis C virus (HCV). HCV infection can evolve into cirrhosis of the liver and its complications, which are ultimately responsible for more than 350,000 deaths every year. Antiviral therapy, when successful, is able to decrease the rate of progression and increase survival. Two types of therapies are currently available, ie, interferon-based therapies and interferon-free ones. The latter have several advantages in terms of safety and tolerability, and could be used even in the most advanced stages of the disease. However, their use is restricted to some viral genotypes (genotype 2 and 3) and they are expensive. Several molecules are in an advanced phase of development. This review deals with the pharmacokinetics, pharmacodynamics, tolerability, and safety of asunaprevir, an inhibitor of HCV nonstructural 3 protease. Asunaprevir exerts optimal in vitro activity particularly against HCV genotypes 1 and 4, and its pharmacokinetic profile enables twice daily administration. The drawback of asunaprevir, and of all protease inhibitors, is its low barrier to resistance. Consequently, it is used in association with other drugs to prevent resistance. Specifically, when combined with daclatasvir, an NS5A inhibitor, asunaprevir results in a very high rate of viral eradication in both treatment-naïve and treatment-experienced patients, with a sustained virological response rate of 80%-90%. Tolerability is fair; in fact, asunaprevir is associated with a transient increase in aminotransferase levels, which is mild in most cases. In conclusion, asunaprevir is a good candidate component of interferon-free combinations and may revolutionize the treatment of chronic HCV infection in the near future.

The efficacy and safety of telaprevir - a new protease inhibitor against hepatitis C virus

IMPORTANCE OF THE FIELD

Hepatitis C virus (HCV) is the main agent of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma in the western world. It affects more than 170 million people worldwide. HCV treatment, based on the combination of Peg-interferon and ribavirin, is effective in about 50% of treated patients. Therefore, there is a need to develop new drugs active against HCV.

AREAS COVERED IN THIS REVIEW

Data were obtained by searching for all full articles on Medline and abstracts presented at major international congresses on viral hepatitis.

WHAT THE READER WILL GAIN

A review of clinical data about the efficacy and safety of telaprevir (VX-950), the HCV protease inhibitor that is in the most advanced phase of clinical development.

TAKE HOME MESSAGE

Telaprevir has an acceptable pharmacokinetic profile and seems to be a potent antiviral drug against HCV, although, owing to a low genetic barrier, resistant variants emerge within a few days when used in monotherapy, thereby decreasing its efficacy. Consequently, telaprevir has been combined with pegylated-interferon and ribavirin in clinical trials. This triple combination is more effective but has a higher rate of adverse events (notably rash) than the standard of care, despite the shorter duration of therapy.

Development of ocular myasthenia during pegylated interferon and ribavirin treatment for chronic hepatitis C

A 63-year-old male experienced sudden diplopia after 9 weeks of administration of pegylated interferon (IFN) alpha-2b and ribavirin for chronic hepatitis C (CHC). Ophthalmologic examinations showed ptosis on the right upper lid and restricted right eye movement without any other neurological signs. A brain imaging study and repetitive nerve stimulation test indicated no abnormality. The acetylcholine receptor antibody titer and response to acetylcholinesterase inhibitors were negative, and the results of thyroid function tests were normal. The patient's ophthalmological symptoms improved rapidly 3 weeks after discontinuation of pegylated IFN alpha-2b and ribavirin. The ocular myasthenia associated with combination therapy of pegylated IFN alpha-2b and ribavirin for CHC is very rarely reported; therefore, we present this case with a review of the various eye complications of IFN therapy.

Celiac disease--sandwiched between innate and adaptive immunity

Celiac disease (CD) patients are intolerant to gluten, proteins in wheat, and related cereals. Virtually all patients are human leukocyte antigen (HLA)-DQ2 or HLA-DQ8 positive and several studies have demonstrated that CD4 T cells specific for (modified) gluten peptides bound to these HLA-DQ molecules are found in patients but not in control subjects. These T cell responses are therefore thought to be responsible for disease development. Many immunogenic gluten peptides which may relate to the disease-inducing properties of gluten have now been identified. In addition, gluten can stimulate IL-15 production that ultimately leads to NKG2D-mediated epithelial cell killing. However, CD develops in only a minority of HLA-DQ2 and HLA-DQ8 individuals. This may be attributed to the default setting of the intestinal immune system: induction and maintenance of tolerance to dietary components and commensal flora. Although at present it is unknown why tolerance in CD is not established or broken, both environmental and genetic factors have been implicated. There is strong evidence for the existence of genes or gene variants on chromosomes 5, 6, and 19 that predispose to CD. In addition, type I interferons have been implicated in development of several autoimmune disorders, including CD. Thus, viral infection and/or tissue damage in the intestine may cause inflammation and induce protective Th1-mediated immunity leading to loss of tolerance for gluten. Once tolerance is broken, a broad gluten-reactive T cell repertoire may develop through determinant spreading. This may be a critical step toward full-blown disease.

Effects of cytokines on acetylcholine receptor expression: implications for myasthenia gravis

Myasthenia gravis is an autoimmune disease associated with thymic pathologies, including hyperplasia. In this study, we investigated the processes that may lead to thymic overexpression of the triggering Ag, the acetylcholine receptor (AChR). Using microarray technology, we found that IFN-regulated genes are more highly expressed in these pathological thymic tissues compared with age- and sex-matched normal thymus controls. Therefore, we investigated whether proinflammatory cytokines could locally modify AChR expression in myoid and thymic epithelial cells. We found that AChR transcripts are up-regulated by IFN-gamma, and even more so by IFN-gamma and TNF-alpha, as assessed by real-time RT-PCR, with the alpha-AChR subunit being the most sensitive to this regulation. The expression of AChR protein was increased at the cytoplasmic level in thymic epithelial cells and at the membrane in myoid cells. To examine whether IFN-gamma could influence AChR expression in vivo, we analyzed AChR transcripts in IFN-gamma gene knock-out mice, and found a significant decrease in AChR transcript levels in the thymus but not in the muscle, compared with wild-type mice. However, up-regulation of AChR protein expression was found in the muscles of animals with myasthenic symptoms treated with TNF-alpha. Altogether, these results indicate that proinflammatory cytokines influence the expression of AChR in vitro and in vivo. Because proinflammatory cytokine activity is evidenced in the thymus of myasthenia gravis patients, it could influence AChR expression and thereby contribute to the initiation of the autoimmune anti-AChR response.

Type I interferons (alpha/beta) in immunity and autoimmunity

The significance of type I interferons (IFN-alpha/beta) in biology and medicine renders research on their activities continuously relevant to our understanding of normal and abnormal (auto) immune responses. This relevance is bolstered by discoveries that unambiguously establish IFN-alpha/beta, among the multitude of cytokines, as dominant in defining qualitative and quantitative characteristics of innate and adaptive immune processes. Recent advances elucidating the biology of these key cytokines include better definition of their complex signaling pathways, determination of their importance in modifying the effects of other cytokines, the role of Toll-like receptors in their induction, their major cellular producers, and their broad and diverse impact on both cellular and humoral immune responses. Consequently, the role of IFN-alpha/beta in the pathogenesis of autoimmunity remains at the forefront of scientific inquiry and has begun to illuminate the mechanisms by which these molecules promote or inhibit systemic and organ-specific autoimmune diseases.