[Oral disease-modifying agents in relapsing-remitting multiple sclerosis]. / Szájon át szedheto immunmoduláns kezelési lehetoségek szklerózis multiplexben.

In relapsing-remitting multiple sclerosis, only parenteral immunomodulatory treatments existed for 15 years, until 2010. In recent years, novel disease-modifying agents became available with new mechanisms of action and oral application, which expanded therapeutic options. Thus, when making therapeutic decisions, more and new aspects should be considered, and the daily practice of patient management has been changed due to the different profile of possible side-effects. The authors review the mechanism of action, pharmacokinetics, studies regarding efficacy, side-effects of first- and second line oral disease-modifying treatments and provide practical guide of their everyday usage.

Immunosuppressants increase the levels of natural autoantibodies reactive with glycosaminoglycans in myasthenia gravis.

Increasing number of evidences support the role of glycosylation in the evolution of autoimmunity. We examined carbohydrate-reactive natural autoantibodies systematically for the first time in patients with autoimmune myasthenia gravis. Antibodies reactive to glycosaminoglycans were measured with CovaLink ELISA in the sera of 59 myasthenia patients as well as in 54 healthy controls. We used the GlycoChip carbohydrate array to characterize individual carbohydrate recognition patterns. Chondroitin-sulphate C and anti-α-mannose-specific IgG levels were significantly elevated in myasthenia patients. Unexpectedly, we found that immunosuppressants increased the levels of the protective IgM glycosaminoglycan-reactive natural antibodies demonstrating a new role for these agents in immunoregulation.

Bayesian systems-based genetic association analysis with effect strength estimation and omic wide interpretation: a case study in rheumatoid arthritis.

Rich dependency structures are often formed in genetic association studies between the phenotypic, clinical, and environmental descriptors. These descriptors may not be standardized, and may encompass various disease definitions and clinical endpoints which are only weakly influenced by various (e.g., genetic) factors. Such loosely defined complex intermediate clinical phenotypes are typically used in follow-up candidate gene association studies, e.g., after genome-wide analysis, to deepen the understanding of the associations and to estimate effect strength. This chapter discusses a solid methodology, which is useful in such a scenario, by using probabilistic graphical models, namely, Bayesian networks in the Bayesian statistical framework. This method offers systematically scalable, comprehensive hierarchical hypotheses about multivariate relevance. We discuss its workflow: from data engineering to semantic publication of the results. We overview the construction, visualization, and interpretation of complex hypotheses related to the structural analysis of relevance. Furthermore, we illustrate the use of a dependency model-based relevance measure, which takes into account the structural properties of the model, for quantifying the effect strength. Finally, we discuss the "interpretational" or translational challenge of a genetic association study, with a focus on the fusion of heterogeneous omic knowledge to reintegrate the results into a genome-wide context.

The modifying effect a PMP22 deletion in a family with Charcot-Marie-Tooth type 1 neuropathy due to an EGR2 mutation.

BACKGROUND: Mutations of both the PMP22 and EGR2 genes cause Charcot-Marie-Tooth (CMT) disease type 1. Deletion of the PMP22 gene, results in hereditary neuropathy with liability to pressure palsies. More publications exist about the interaction of PMP22 duplication and other CMT-causing gene mutations. In these cases the intrafamiliar discordant phenotypes draw the attention to the possible role of modifying genes. The gene-gene interactions between the PMP22 and EGR2 genes are not well understood. CASE REPORT: We report two brothers with late onset CMT1 due to a c. 1142 G>A (Arg381His) heterozygous substitution in the EGR2 gene. Additionally, the older brother with the less severe symptoms harbored the PMP22 gene deletion also. CONCLUSION: The coexistence of the two genetic alterations did not aggravate the clinical symptoms. Moreover, the PMP22 deletion appeared to have a beneficial modifying effect, thus implying potential gene-gene interaction of PMP22 and EGR2. PMP22 deletion may increase Schwann cells proliferation and compensate the dominant-negative effect of the Arg381 His substitution in the EGR2 gene.

Non-synonymous single nucleotide polymorphisms in genes for immunoregulatory galectins: association of galectin-8 (F19Y) occurrence with autoimmune diseases in a Caucasian population.

BACKGROUND: Galectins are potent immune regulators, with galectin-8 acting as a pro-apoptotic effector on synovial fluid cells and thymocytes and stimulator on T-cells. To set a proof-of-principle example for risk assessment in autoimmunity, and for a mutation affecting physiological galectin sensor functions, a polymorphism in the coding region of the galectin-8 gene (rs2737713; F19Y) was studied for its association with two autoimmune disorders, i.e. rheumatoid arthritis and myasthenia gravis. METHODS: A case-control analysis and a related quantitative trait-association study were performed to investigate the association of this polymorphism in patients (myasthenia gravis 149, rheumatoid arthritis 214 and 134 as primary and repetitive cohorts, respectively) and 365 ethnically matched (Caucasian) healthy controls. Distribution was also investigated in patients grouped according to their antibody status and age at disease onset. Comparative testing for lectin activity was carried out in ELISA/ELLA-based binding tests with both wild-type and F19Y mutant galectin-8 from peripheral blood mononuclear cell lysates of healthy individuals with different genotypes as well as with recombinant wild-type and F19Y mutant galectin-8 proteins. RESULTS: A strong association was found for rheumatoid arthritis, and a mild one with myasthenia gravis. Furthermore, the presence of the sequence deviation also correlated with age at disease onset in the case of rheumatoid arthritis. The F19Y substitution did not appear to affect carbohydrate binding in solid-phase assays markedly. GENERAL SIGNIFICANCE: This is the first report of an association between a galectin-based polymorphism leading to a mutant protein and autoimmune diseases, with evidence for antagonistic pleiotropy.

Interleukin-4 receptor alpha polymorphisms in autoimmune myasthenia gravis in a Caucasian population.

Autoimmune myasthenia gravis is a T-cell-dependent, antibody-mediated, rare neuromuscular disorder. Interleukin-4, acting via interleukin-4 receptor alpha, plays a pivotal role in B-cell differentiation and antibody production and has been implicated to influence disease progression in experimental autoimmune myasthenia gravis. Polymorphisms of the interleukin-4 receptor alpha gene have been shown to be associated with various autoimmune diseases. We compared the distribution of three polymorphisms of the interleukin-4 receptor alpha gene (S503P, rs1805015, Q576R, rs1801275, I75V, rs1805010), all affecting interleukin-4 signaling, in two cohorts of myasthenia gravis patients with ethnically matched controls. Although the distribution of the S503P and Q576R polymorphisms did not differ significantly between the groups, the frequency of the GG rare homozygote genotype of the I75V polymorphism was significantly higher in patients with myasthenia gravis. Our data suggest that the reduced responsiveness to interleukin-4 because the I75V polymorphism may contribute to the pathogenesis of myasthenia gravis.

[Therapy for anti-MuSK antibody positive myasthenia gravis]. / A MuSK-ellenes antitest pozitív myasthenia gravis kezelése.

The authors report the case of a 27-year-old woman with muscle-specific receptor tyrosine kinase antibody positive myasthenia with predominantly ocular and bulbar symptoms. Both edrophonium and low dose (4×30 mg/day) pyridostigmin resulted in cholinergic side effects including fasciculation mainly in the facial and neck muscles, and excessive salivation. The patient responded well to a relatively high dose of chronic corticosteroid treatment (methyprednisolone 64mg/day), but the decrease of the corticosteroid dose below 16 mg/day induced exacerbation of the clinical symptoms. Immunosuppression with azathioprine and methotrexate failed to maintain the clinical improvement. However, plasma exchange was always very effective, and all clinical symptoms improved significantly. The authors conclude that patients with muscle-specific receptor tyrosine kinase antibody positive myasthenia gravis should have an individual treatment protocol differing from those used in patients who do not have this antibody but are positive for acetylcholine-receptor antibody. Identification of the pathogenic antibody in the early stage of myasthenia gravis may help to develop the optimal, individualized treatment strategy, to avoid severe side effects, and to achieve fast improvement.

Membrane vesicles, current state-of-the-art: emerging role of extracellular vesicles.

Release of membrane vesicles, a process conserved in both prokaryotes and eukaryotes, represents an evolutionary link, and suggests essential functions of a dynamic extracellular vesicular compartment (including exosomes, microparticles or microvesicles and apoptotic bodies). Compelling evidence supports the significance of this compartment in a broad range of physiological and pathological processes. However, classification of membrane vesicles, protocols of their isolation and detection, molecular details of vesicular release, clearance and biological functions are still under intense investigation. Here, we give a comprehensive overview of extracellular vesicles. After discussing the technical pitfalls and potential artifacts of the rapidly emerging field, we compare results from meta-analyses of published proteomic studies on membrane vesicles. We also summarize clinical implications of membrane vesicles. Lessons from this compartment challenge current paradigms concerning the mechanisms of intercellular communication and immune regulation. Furthermore, its clinical implementation may open new perspectives in translational medicine both in diagnostics and therapy.

A novel galectin-1 and interleukin 2 receptor ß haplotype is associated with autoimmune myasthenia gravis.

Galectin-1 (LGALS1) and interleukin receptor 2ß (IL2Rß) are regulators of T-cell activation. Here we evaluated the association of regulatory region polymorphisms of the LGALS1 (rs4820293, rs4820294) and IL2Rß (rs743777, rs228941) genes in 146 Caucasian myasthenia gravis patients compared to 291 ethnically matched controls. A significant difference was found in the distribution of the rs4820293/rs743777 polymorphism haplotypes (p<0.01). The rs4820293 polymorphism, previously not described to be associated with any disease, does not affect LGALS1 expression in peripheral mononuclear cells and skeletal muscle. Pathway analysis revealed interaction between LGALS1 and IL2Rß suggesting a role of these proteins in this rare disease.

Hepatitis C virus RNA replication requires a conserved structural motif within the transmembrane domain of the NS5B RNA-dependent RNA polymerase.

Hepatitis C virus (HCV) nonstructural protein 5B (NS5B), the viral RNA-dependent RNA polymerase (RdRp), is a tail-anchored protein with a highly conserved C-terminal transmembrane domain (TMD) that is required for the assembly of a functional replication complex. Here, we report that the TMD of the HCV RdRp can be functionally replaced by a newly identified analogous membrane anchor of the GB virus B (GBV-B) NS5B RdRp. Replicons with a chimeric RdRp consisting of the HCV catalytic domain and the GBV-B membrane anchor replicated with reduced efficiency. Compensatory amino acid changes at defined positions within the TMD improved the replication efficiency of these chimeras. These observations highlight a conserved structural motif within the TMD of the HCV NS5B RdRp that is required for RNA replication.

Oestrogen receptor alpha gene intronic polymorphisms and autoimmune myasthenia gravis in Caucasian women.

Autoimmune myasthenia gravis is a disorder with a complex pathomechanism in which sex hormones, in particular oestrogen, have long been considered to play a role. Here we report the result of a case-control study which evaluated the association of two oestrogen receptor alpha gene polymorphisms with myasthenia gravis in Caucasian patients. PvuII (rs2234693) and XbaI (rs9340799) restriction fragment polymorphisms of the oestrogen receptor alpha gene were analyzed in 113 female myasthenia patients and 184 female controls. Distribution of these polymorphisms was compared with PCR-RFLP. Patients were divided into groups according to their oestrogen receptoralpha genotypes, and acetylcholine receptor antibody status and age of onset were compared between the groups. We found no significant difference between any of the groups implying that these two polymorphisms probably do not play a role in the pathomechanism of myasthenia gravis in Caucasian women.

HoxC4 binds to the promoter of the cytidine deaminase AID gene to induce AID expression, class-switch DNA recombination and somatic hypermutation.

The cytidine deaminase AID (encoded by Aicda in mice and AICDA in humans) is critical for immunoglobulin class-switch recombination (CSR) and somatic hypermutation (SHM). Here we show that AID expression was induced by the HoxC4 homeodomain transcription factor, which bound to a highly conserved HoxC4-Oct site in the Aicda or AICDA promoter. This site functioned in synergy with a conserved binding site for the transcription factors Sp1, Sp3 and NF-kappaB. HoxC4 was 'preferentially' expressed in germinal center B cells and was upregulated by engagement of CD40 by CD154, as well as by lipopolysaccharide and interleukin 4. HoxC4 deficiency resulted in impaired CSR and SHM because of lower AID expression and not some other putative HoxC4-dependent activity. Enforced expression of AID in Hoxc4(-/-) B cells fully restored CSR. Thus, HoxC4 directly activates the Aicda promoter, thereby inducing AID expression, CSR and SHM.

Genetically determined neuropathy (CMT 1A) accompanied by immune dysfunction: a case report.

Peripheral Myelin Protein 22 (PMP22) is mostly expressed in Schwann cells where it is essential in the compaction of myelin. The duplication of the PMP22 gene results in a hereditary demyelinating neuropathy of the Charcot-Marie-Tooth type 1A (CMT1A). So far there are only a few case reports suggesting that dysimmune mechanisms may take part in the pathophysiology of this disease. We describe three siblings carrying the duplication of the PMP22 gene, with a significant reduction of serum immunoglobulin G levels in all three cases and sural nerve vasculitis in the two women, which supports the proposition, that immune dysfunction may accompany this disease in some cases.

[Maternally inherited diabetes mellitus, deafness, chronic progressive external ophthalmoplegia and myopathy as the result of A3243G mutation of mtDNA]. / Maternalisan öröklôdô diabetes mellitus, nagyothallás, kronikus progressziv ophthalmoplegia externa es myopathia mint az MTDNS A3243G-mutáció következménye.

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome are caused mainly by the A3243G mutation of the mitochondrial genome. The A3243G substitution of mitochondrial DNA (mtDNA) is also responsible for various, other clinical phenotypes and syndromes. Here we report the case of a 33-year-old woman, with childhood onset ophthalmoplegia externa, progressive, generalised exercise intolerability, muscle weakness, hypacusis and diabetes mellitus as the symptoms of mitochondrial disease. Genetic analysis of the mitochondrial DNA revealed a heteroplasmic A to G substitution at position 3243 in the tRNS Leu(UUR) gene. In our case the classical MELAS phenotype has not yet appeared, however, some examples show in the literature that maternally inherited diabetes mellitus, progressive hypacusis, progressive ophthalmoplegia externa, exercise intolerance, and myopathy are often linked to as isolated symptoms of A3243G mutation. The phenotype in the family is consistent, the proband's daughter has ptosis, exercise intolerance, and myopathy, too. A brief summary of the different clinical phenotypes associated with A3243G mutation, and of the different mtDNA mutations which can cause chronic progressive ophthalmoplegia externa (CPEO) will also be reviewed in this case report.

Conserved determinants for membrane association of nonstructural protein 5A from hepatitis C virus and related viruses.

Nonstructural protein 5A (NS5A) is a membrane-associated essential component of the hepatitis C virus (HCV) replication complex. An N-terminal amphipathic alpha helix mediates in-plane membrane association of HCV NS5A and at the same time is likely involved in specific protein-protein interactions required for the assembly of a functional replication complex. The aim of this study was to identify the determinants for membrane association of NS5A from the related GB viruses and pestiviruses. Although primary amino acid sequences differed considerably, putative membrane anchor domains with amphipathic features were predicted in the N-terminal domains of NS5A proteins from these viruses. Confocal laser scanning microscopy, as well as membrane flotation analyses, demonstrated that NS5As from GB virus B (GBV-B), GBV-C, and bovine viral diarrhea virus, the prototype pestivirus, display membrane association characteristics very similar to those of HCV NS5A. The N-terminal 27 to 33 amino acid residues of these NS5A proteins were sufficient for membrane association. Circular dichroism analyses confirmed the capacity of these segments to fold into alpha helices upon association with lipid-like molecules. Despite structural conservation, only very limited exchanges with sequences from related viruses were tolerated in the context of functional HCV RNA replication, suggesting virus-specific interactions of these segments. In conclusion, membrane association of NS5A by an N-terminal amphipathic alpha helix is a feature shared by HCV and related members of the family Flaviviridae. This observation points to conserved roles of the N-terminal amphipathic alpha helices of NS5A in replication complex formation.

DNA repair in antibody somatic hypermutation.

Somatic hypermutation (SHM) underlies the generation of a diverse repertoire of high-affinity antibodies. It is effected by a two-step process: (i) DNA lesions initiated by activation-induced cytidine deaminase (AID), and (ii) lesion repair by the combined intervention of DNA replication and repair factors that include mismatch repair (MMR) proteins and translesion DNA synthesis (TLS) polymerases. AID and TLS polymerases that are crucial to SHM, namely polymerase (pol) theta, pol zeta and pol eta, are induced in B cells by the stimuli that are required to trigger this process: B-cell receptor crosslinking and CD40 engagement by CD154. These polymerases, together with MMR proteins and other DNA replication and repair factors, could assemble to form a multimolecular complex ("mutasome") at the site of DNA lesions. Molecular interactions in the mutasome would result in a "polymerase switch", that is, the substitution of the high-fidelity replicative pol delta and pol epsilon with the TLS pol theta, pol eta, Rev1, pol zeta and, perhaps, pol iota, which are error-prone and crucially insert mismatches or mutations while repairing DNA lesions. Here, we place these concepts in the context of the existing in vivo and in vitro findings, and discuss an integrated mechanistic model of SHM.