Novel Genetic Variants Distinguishing Myelin Oligodendrocyte Glycoprotein-IgG-Positive From Myelin Oligodendrocyte Glycoprotein-IgG-Negative Pediatric Acute Disseminated Encephalomyelitis in Northern China.

BACKGROUND: Acute disseminated encephalomyelitis (ADEM) is a common phenotype in children with myelin oligodendrocyte glycoprotein IgG (MOG-IgG)-associated disease. We aimed to identify novel genetic variants that distinguish children with MOG-IgG-positive ADEM (MOG-IgG+ ADEM) from children with MOG-IgG-negative ADEM (MOG-IgG- ADEM) using whole exome sequencing (WES) analysis. METHODS: We conducted a two-stage study design. First, we performed WES on five patients with MOG-IgG+ ADEM and five patients with MOG-IgG- ADEM. Following bioinformatics analysis, the candidate variant list was constructed. Second, 29 children with MOG-IgG+ ADEM and 27 children with MOG-IgG- ADEM, together with discovery cohort, were genotyped to identify the novel variants. RESULTS: WES resulted in 33,999 variants, and 5388 nonsynonymous variants were selected for downstream analysis. In total, 118 protein-affecting variants that were significantly different between the two groups were identified. Together with the five variants extracted from the literature, 49 variants were selected as the candidate variant list for genotyping in the replication cohort. Finally, we identified three variants: rs11171951 in NACα, rs231775 in CTLA4, and rs11171951 in GOLGA5, which were significantly different between MOG-IgG+ ADEM and MOG-IgG- ADEM. Only rs12440118 in NACα remained significant after Bonferroni correction for multiple testing (Padj < 0.001). CONCLUSIONS: We identified strong associations between NACα, CTLA4, and GOLGA5 variants and MOG-IgG+ ADEM in a Han Chinese population of Northern China, which may present novel genetic risk factor distinguishing patients with MOG-IgG+ ADEM from those with MOG-IgG- ADEM.

Neurotoxic potential of reactive astrocytes in canine distemper demyelinating leukoencephalitis.

Canine distemper virus (CDV) causes a fatal demyelinating leukoencephalitis in young dogs resembling human multiple sclerosis. Astrocytes are the main cellular target of CDV and undergo reactive changes already in pre-demyelinating brain lesions. Based on their broad range of beneficial and detrimental effects in the injured brain reactive astrogliosis is in need of intensive investigation. The aim of the study was to characterize astrocyte plasticity during the course of CDV-induced demyelinating leukoencephalitis by the aid of immunohistochemistry, immunofluorescence and gene expression analysis. Immunohistochemistry revealed the presence of reactive glial fibrillary acidic protein (GFAP)+ astrocytes with increased survivin and reduced aquaporin 4, and glutamine synthetase protein levels, indicating disturbed blood brain barrier function, glutamate homeostasis and astrocyte maladaptation, respectively. Gene expression analysis revealed 81 differentially expressed astrocyte-related genes with a dominance of genes associated with neurotoxic A1-polarized astrocytes. Accordingly, acyl-coA synthetase long-chain family member 5+/GFAP+, and serglycin+/GFAP+ cells, characteristic of A1-astrocytes, were found in demyelinating lesions by immunofluorescence. In addition, gene expression revealed a dysregulation of astrocytic function including disturbed glutamate homeostasis and altered immune function. Observed findings indicate an astrocyte polarization towards a neurotoxic phenotype likely contributing to lesion initiation and progression in canine distemper leukoencephalitis.

Analysis By Deep Sequencing of Discontinued Neurotropic Yellow Fever Vaccine Strains.

Deep sequencing of live-attenuated viral vaccines has focused on vaccines in current use. Here we report characterization of a discontinued live yellow fever (YF) vaccine associated with severe adverse events. The French neurotropic vaccine (FNV) strain of YF virus was derived empirically in 1930 by 260 passages of wild-type French viscerotropic virus (FVV) in mouse brain. The vaccine was administered extensively in French-speaking Africa until discontinuation in 1982, due to high rates of post-vaccination encephalitis in children. Using rare archive strains of FNV, viral RNAs were sequenced and analyzed by massively parallel, in silico methods. Diversity and specific population structures were compared in reference to the wild-type parental strain FVV, and between the vaccine strains themselves. Lower abundance of polymorphism content was observed for FNV strains relative to FVV. Although the vaccines were of lower diversity than FVV, heterogeneity between the vaccines was observed. Reversion to wild-type identity was variably observed in the FNV strains. Specific population structures were recovered from vaccines with neurotropic properties; loss of neurotropism in mice was associated with abundance of wild-type RNA populations. The analysis provides novel sequence evidence that FNV is genetically unstable, and that adaptation of FNV contributed to the neurotropic adverse phenotype.

Hiperventilación central neurogénica en un paciente con encefalomielitis aguda diseminada posvacunal / Central neurogenic hyperventilation in a patient with post-vaccination acute disseminated encephalomyelitis

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IL-27 limits central nervous system viral clearance by promoting IL-10 and enhances demyelination.

IL-27 is a pleiotropic member of the IL-6 and IL-12 cytokine family composed of the IL-27p28 and the EBV-induced gene 3. IL-27 and its receptor mRNA are both upregulated in the CNS during acute encephalomyelitis induced by the JHM strain of mouse hepatitis virus (JHMV) and sustained during viral persistence. Contributions of IL-27 to viral pathogenesis were evaluated by infection of IL-27Rα-chain-deficient (IL-27Rα(-/-)) mice. The absence of IL-27 signaling accelerated virus control within the CNS associated with increased IFN-γ secreting virus-specific CD4+ and CD8+ T cells. Abrogation of IL-27 signaling did not affect virus-specific CD8+ T cell-mediated IL-10 production or cytolytic activity or Foxp3+ regulatory T cell populations. However, IL-10 production by virus-specific CD4+ T cells was reduced significantly. Despite increased T cell-mediated antiviral function in IL-27Rα(-/-) mice, the virus persisted in the CNS at similar levels as in wild-type mice. Nevertheless, IL-27Rα(-/-) mice exhibited decreased clinical disease during persistence, coincident with less severe demyelination, the hallmark tissue damage associated with JHMV infection. Overall, these data demonstrate that in contrast to viral infections at other sites, IL-27 does not play a proinflammatory role during JHMV-induced encephalomyelitis. Rather, it limits CNS inflammation and impairs control of CNS virus replication via induction of IL-10 in virus-specific CD4+ T cells. Furthermore, in contrast to its protective role in limiting CNS autoimmunity and preventing immunopathology, these data define a detrimental role of IL-27 in promoting demyelination by delaying viral control.

Does HLA Class II haplotype play a role in adult acute disseminated encephalomyelitis? Preliminary findings from a Southern Italy hospital-based study.

Acute Disseminated Encephalomyelitis (ADEM) is an acute, multifocal, monophasic, inflammatory demyelinating disease of the central nervous system that affects predominantly children. Aim of the study was to evaluate the distribution of Human Leukocyte Antigen (HLA) class II haplotype in adult ADEM patients, in order to better characterize this rare clinical entity. Six patients (3 males and 3 females; median age 50 years) with ADEM were retrospectively studied in our Neurology Unit; 29 healthy subjects (8 males and 21 females, mean age 43.4±14.3) were the control group. All the study subjects were molecularly typed for HLA class II haplotype. The frequencies of HLA-DRB1*16 (17% vs 3% in control group; Py=0.02) and HLA-DQB1*05 (42% against 24% in the control group; Py=0.010), as well as the association HLA-DRB1*16/HLA-DQB1*05 were significantly increased in ADEM population compared to the control group. The frequencies of allelic association between 13-04 (P < 0.01) and homozygosis 14 (P < 0.05) alleles at HLA-DRB1* locus and 05-02 (P < 0.05) alleles at HLA-DQB* locus also were increased in ADEM patients. Our preliminary data provide further evidence that the HLA-DR/DQ haplotypes may be involved in susceptibility to immunomediate demyelinating diseases of central nervous system in the Caucasian population.

Acute encephalopathy and encephalitis caused by influenza virus infection.

PURPOSE OF REVIEW: Influenza-associated acute encephalopathy/encephalitis (IAE) is an uncommon but serious complication with high mortality and neurological sequelae. This review discusses recent progress in IAE research for a better understanding of the disease features, populations, outcomes, diagnosis, and pathogenesis. RECENT FINDINGS: In recent years, many IAE cases were reported from many countries, including Japan, Canada, Australia, Austria, The Netherlands, United States, Sweden, and other countries and regions. During the novel influenza A/H1N1 pandemic, many IAE cases with A/H1N1 infection in children were reported, particularly in those hospitalized with influenza infection. Pathogenesis of IAE is not fully understood but may involve viral invasion of the CNS, proinflammatory cytokines, metabolic disorders, or genetic susceptibility. An autosomal dominant viral acute necrotizing encephalopathy (ANE) was recently found to have missense mutations in the gene Ran-binding 2 (RANBP2). Another recurrent ANE case following influenza A infection was also reported in a genetically predisposed family with an RANBP2 mutation. SUMMARY: Although IAE is uncommon, compared with the high incidence of influenza infection, it is severe. However, this complication is not duly recognized by health practitioners. Recent advances highlight the threat of this complication, which will help us to have a better understanding of IAE.

Is it ADEM, POLG, or both?

OBJECTIVE: To describe a child with apparent brain biopsy-confirmed acute disseminated encephalomyelitis (ADEM) but genetic confirmation of compound heterozygosity for DNA mutations of the polymerase gamma (POLG) gene. DESIGN: Case report. SETTING: Tertiary referral center. PATIENT: A 4-year-old boy presented with ataxia and encephalopathy. RESULTS: Magnetic resonance imaging demonstrated multiple focal areas of T2 prolongation. The patient's family refused steroid treatment. His symptoms improved then progressed. Magnetic resonance imaging findings also progressed. A cerebrospinal fluid specimen revealed myelin basic protein and oligoclonal bands. A brain biopsy specimen demonstrated demyelination, suggesting progression of ADEM. However, polymerase chain reaction amplification and sequencing revealed 2 heterozygous mutations of the POLG gene, suggesting mitochondrial disease. The patient died 9 months after his initial presentation. CONCLUSIONS: This case raises interesting questions about whether ADEM triggered severe neurologic degeneration in a patient with mitochondrial disease, whether mitochondrial disease predisposed to a pathologic immune response, or whether mitochondrial disease can mimic an autoimmune disease. Mitochondrial disease-causing mutations may help explain the poor outcome in some cases of apparent autoimmune central nervous system disease.

Acute disseminated encephalomyelitis: clinical features, HLA DRB1*1501, HLA DRB1*1503, HLA DQA1*0102, HLA DQB1*0602, and HLA DPA1*0301 allelic association study.

We evaluated the frequency, demographic, clinical, disability evolution and genetic association of HLA DRB1*1501, DRB1*1503, DQA1*0102, DQB1*0602 and DPA1*0301 alleles in patients diagnosed as acute disseminated encephalomyelitis (ADEM) among a population of CNS demyelinating diseases. Fifteen patients (8.4%) of our series were diagnosed as ADEM. The mean age onset was 35.23 years (range 12 to 77), 53.3% were male and follow-up range was 8.5 to 16 years. Two cases (13.3%) had a preceding infection before neurological symptoms, one presented a parainfectious demyelinating, and one case had been submitted to hepatitis B vaccination four weeks before the clinical onset. The EDSS range was 3.0 to 9.5. Eight patients (53.3%) presented MRI with multiple large lesions. CSF was normal in 73.3%. The severe disability observed at EDSS onset improved in 86.66% patients. The genetic susceptibility for ADEM was significantly associated with the HLA DQB1*0602, DRB1*1501 and DRB1*1503 alleles (<0.05) in monophasic ADEM.

Acute disseminated encephalomyelitis: clinical features, HLA DRB1*1501, HLA DRB1*1503, HLA DQA1*0102, HLA DQB1*0602, and HLA DPA1*0301 allelic association study / Encefalomielite aguda disseminada: características clínicas e estudo de associação com os alelos HLA DRB1*1501, HLA DRB1*1503, HLA DQA1*0102, HLA DQB1*0602 e DPA1*0301

We evaluated the frequency, demographic, clinical, disability evolution and genetic association of HLA DRB1*1501, DRB1*1503, DQA1*0102, DQB1*0602 and DPA1*0301 alleles in patients diagnosed as acute disseminated encephalomyelitis (ADEM) among a population of CNS demyelinating diseases. Fifteen patients (8.4 percent) of our series were diagnosed as ADEM. The mean age onset was 35.23 years (range 12 to 77), 53.3 percent were male and follow-up range was 8.5 to 16 years. Two cases (13.3 percent) had a preceding infection before neurological symptoms, one presented a parainfectious demyelinating, and one case had been submitted to hepatitis B vaccination four weeks before the clinical onset. The EDSS range was 3.0 to 9.5. Eight patients (53.3 percent) presented MRI with multiple large lesions. CSF was normal in 73.3 percent. The severe disability observed at EDSS onset improved in 86.66 percent patients. The genetic susceptibility for ADEM was significantly associated with the HLA DQB1*0602, DRB1*1501 and DRB1*1503 alleles (<0.05) in monophasic ADEM.

Avaliamos as frequencia, características demográficas, clínicas e de associação genética dos alelos HLA DRB1*1501, DRB1*1503, DQA1*0102, DQB1*0602 e DPA1*0301 em pacientes com diagnóstico de encefalomielite aguda disseminada (ADEM) em população com doença desmielinizante do SNC. Quinze (8,4 por cento) pacientes de nossa série foram diagnosticados como ADEM. A média de idade foi 35,23 anos (variando entre 12 e 77), 53,3 por cento eram homens e o tempo de acompanhamento variou entre 8,5 e 16 anos. Dois casos (13,3 por cento) apresentaram infecção prévia, um apresentou processo desmielinizante para infeccioso e outro havia se submetido a vacinação para hepatite B quatro semanas antes. O EDSS variou entre 3,0 e 9,5. Oito pacientes (53,3 por cento) apresentaram grandes lesões na RM. O LCR foi normal em 73,3 por cento. A incapacidade grave quantificada pelo EDSS foi seguida de melhora importante em 86,6 por cento dos pacientes. A susceptibilidade genética na ADEM foi significativamente associada com os alelos HLA DQB1*0602, DRB1*1501 e DRB1*1503 (p<0,05) nos pacientes com quadro monofásico.

Pertussis vaccination and epilepsy--an erratic history, new research and the mismatch between science and social policy.

For over 50 years, concerns have been raised about the risk of pertussis vaccine-induced childhood encephalopathy and epilepsy. This article reviews the scientific literature, and the social and historical context in which the scientific, public health and societal views have not always been aligned. Large-scale studies of this issue have produced conflicting results, although the recent consensus is that the risk of vaccine-induced encephalopathy and/or epilepsy, if it exists at all, is extremely low. Risk estimates in the literature have included: risk of a febrile seizure 1 per 19,496 vaccinations; risk of an afebrile seizure 1 per 76,133 vaccinations; risk of encephalopathy after pertussis infection nil-3 cases per million vaccinations. A recent study showed that encephalopathy in 11 out of the 14 children studied, although previously attributed to vaccination, was in fact due an inherited genetic defect of the SCNIA gene that codes for the voltage gated neuronal sodium channel. This study is important because it provides a solid alternative explanation for the perceived pertussis vaccine-encephalopathy association. The interesting possibility is raised that the encephalopathy apparently due to pertussis itself may, in some cases, be due to an SCNIA mutation. It may also, by analogy, shed some light on the continuing debate about other serious long-term adverse effects of vaccination in general.

De-novo mutations of the sodium channel gene SCN1A in alleged vaccine encephalopathy: a retrospective study.

BACKGROUND: Vaccination, particularly for pertussis, has been implicated as a direct cause of an encephalopathy with refractory seizures and intellectual impairment. We postulated that cases of so-called vaccine encephalopathy could have mutations in the neuronal sodium channel alpha1 subunit gene (SCN1A) because of a clinical resemblance to severe myoclonic epilepsy of infancy (SMEI) for which such mutations have been identified. METHODS: We retrospectively studied 14 patients with alleged vaccine encephalopathy in whom the first seizure occurred within 72 h of vaccination. We reviewed the relation to vaccination from source records and assessed the specific epilepsy phenotype. Mutations in SCN1A were identified by PCR amplification and denaturing high performance liquid chromatography analysis, with subsequent sequencing. Parental DNA was examined to ascertain the origin of the mutation. FINDINGS: SCN1A mutations were identified in 11 of 14 patients with alleged vaccine encephalopathy; a diagnosis of a specific epilepsy syndrome was made in all 14 cases. Five mutations predicted truncation of the protein and six were missense in conserved regions of the molecule. In all nine cases where parental DNA was available the mutations arose de novo. Clinical-molecular correlation showed mutations in eight of eight cases with phenotypes of SMEI, in three of four cases with borderline SMEI, but not in two cases with Lennox-Gastaut syndrome. INTERPRETATION: Cases of alleged vaccine encephalopathy could in fact be a genetically determined epileptic encephalopathy that arose de novo. These findings have important clinical implications for diagnosis and management of encephalopathy and, if confirmed in other cohorts, major societal implications for the general acceptance of vaccination.

Acute disseminated encephalomyelitis in children: clinical features and HLA-DR linkage.

This study includes 90 children (41 female and 49 male) in the age range of 2-16 years with acute disseminated encephalomyelitis (ADEM). Thirty-three patients developed ADEM following rubella infection, 26 children following varicella infection, 20 suspected viral aetiology ADEM and 11 multiphasic disseminated encephalomyelitis (MDEM). All patients had neurological, routine laboratory and viral serology study with an enzyme-linked immunosorbent assay. Brain and/or spinal cord magnetic resonance imaging (MRI) were performed in 14 children. A follow-up study was in 1-5 years. Typing of DRB1 gene HLA class II was performed in 38 patients. We established that the varicella and rubella groups had preferential patterns. Rubella ADEM is characterized by acute explosive onset, seizures, coma and moderate pyramidal signs, whereas varicella infection is characterized by cerebella ataxia and mild pyramidal dysfunction. The suspected viral aetiology ADEM was characterized by polisymptomatic presentation. MDEM was characterized by older age of patients (11.6 +/- 2.8 years), more severe and prolonged local neurological symptoms, including myelitis symptoms and marked extrapyramidal signs, with distinct demyelination in MRIs. As a whole, ADEM is associated with DRB1*01 and DRB1*017(03) in the Russian population. Thus, ADEM is a separate autoimmune condition with a specific mechanism due to the type of genetic immunoregulatory base and specificity of viral trigger.

Apoptosis of T lymphocytes in acute disseminated encephalomyelitis.

Apoptosis has been shown to be an efficient mechanism involved in clearance of T lymphocytes from the brains of animals with acute experimental autoimmune encephalomyelitis (EAE), an animal model for human multiple sclerosis. In this report we describe a case of acute disseminated encephalomyelitis following general measles infection. In this disease, which closely mimics the pathology of acute EAE we found a high percentage (30%) of apoptotic T cells. This indicates that in both rodent and human brain clearance of T cell-mediated inflammation follows similar mechanisms.