Qki is an essential regulator of microglial phagocytosis in demyelination.

The mechanism underpinning the regulation of microglial phagocytosis in demyelinating diseases is unclear. Here, we showed that the Quaking protein (Qki) in microglia was greatly induced by demyelination in the brains of both mice and humans. Deletion of the Quaking gene (Qk) in microglia severely impaired the clearance of myelin debris. Transcriptomic profiling indicated that depletion of Qki impaired total RNA levels and splicing of the genes involved in phagosome formation and maturation. RNA immunoprecipitation (RIP) confirmed the physical interactions between the Qki protein and the mRNAs of Qki targets that are involved in phagocytosis, indicating that Qki regulates their RNA stability. Both Qki depletion and inhibition of Qki target Cd36 greatly reduced the phagocytic activity of microglia and macrophages. The defective uptake and degradation of myelin debris caused by Qki depletion in microglia resulted in unresolved myelin debris that impaired axon integrity, oligodendrocyte maturation, and subsequent remyelination. Thus, our results demonstrate that Qki is an essential regulator of microglia's phagocytic activity under demyelinating conditions.

HLA association in MOG-IgG- and AQP4-IgG-related disorders of the CNS in the Dutch population.

OBJECTIVE: To investigate the possible human leukocyte antigen (HLA) association of both myelin oligodendrocyte glycoprotein (MOG-IgG)-associated diseases (MOGAD) and aquaporin-4 antibody (AQP4-IgG)-positive neuromyelitis optica spectrum disorders (NMOSDs) in the Dutch population with European ancestry to clarify similarities or differences in the immunogenetic background of both diseases. METHODS: Blood samples from patients in the Dutch national MS/NMOSD expert clinic were tested for MOG-IgG and AQP4-IgG using a cell-based assay. HLA Class I and II genotyping was performed in 43 MOG-IgG-seropositive and 42 AQP4-IgG-seropositive Dutch patients with European ancestry and compared with those of 5,604 Dutch healthy blood donors. RESULTS: No significant HLA association was found in MOG-IgG-seropositive patients. The AQP4-IgG-seropositive patients had a significant higher frequency of HLA-A*01 (61.9% vs 33.7%, OR 3.16, 95% CI, 1.707-5.863, p after correction [pc] = 0.0045), HLA-B*08 (61.9% vs 25.6%, OR 4.66, 95% CI, 2.513-8.643, pc < 0.0001), and HLA-DRB1*03 (51.2% vs 27.6%, OR 2.75, 95% CI, 1.495-5.042, pc = 0.0199) compared with controls. CONCLUSIONS: The present study demonstrates differences in the immunogenetic background of MOGAD and AQP4-IgG-positive NMOSD. The strong positive association with HLA-A*01, -B*08, and -DRB1*03 is suggestive of a role of this haplotype in the etiology of AQP4-IgG-positive NMOSD in patients with European ancestry, whereas in MOGAD no evidence was found for any HLA association in these disorders.

Epigenomic signature of adrenoleukodystrophy predicts compromised oligodendrocyte differentiation.

Epigenomic changes may either cause disease or modulate its expressivity, adding a layer of complexity to mendelian diseases. X-linked adrenoleukodystrophy (X-ALD) is a rare neurometabolic condition exhibiting discordant phenotypes, ranging from a childhood cerebral inflammatory demyelination (cALD) to an adult-onset mild axonopathy in spinal cords (AMN). The AMN form may occur with superimposed inflammatory brain demyelination (cAMN). All patients harbor loss of function mutations in the ABCD1 peroxisomal transporter of very-long chain fatty acids. The factors that account for the lack of genotype-phenotype correlation, even within the same family, remain largely unknown. To gain insight into this matter, here we compared the genome-wide DNA methylation profiles of morphologically intact frontal white matter areas of children affected by cALD with adult cAMN patients, including male controls in the same age group. We identified a common methylomic signature between the two phenotypes, comprising (i) hypermethylation of genes harboring the H3K27me3 mark at promoter regions, (ii) hypermethylation of genes with major roles in oligodendrocyte differentiation such as MBP, CNP, MOG and PLP1 and (iii) hypomethylation of immune-associated genes such as IFITM1 and CD59. Moreover, we found increased hypermethylation in CpGs of genes involved in oligodendrocyte differentiation, and also in genes with H3K27me3 marks in their promoter regions in cALD compared with cAMN, correlating with transcriptional and translational changes. Further, using a penalized logistic regression model, we identified the combined methylation levels of SPG20, UNC45A and COL9A3 and also, the combined expression levels of ID4 and MYRF to be good markers capable of discriminating childhood from adult inflammatory phenotypes. We thus propose the hypothesis that an epigenetically controlled, altered transcriptional program may drive an impaired oligodendrocyte differentiation and aberrant immune activation in X-ALD patients. These results shed light into disease pathomechanisms and uncover putative biomarkers of interest for prognosis and phenotypic stratification.

Juvenile Taiep rats have shorter dendritic trees in the dorsal field of the hippocampus without spatial learning disabilities.

Myelin mutant taiep rats show a progressive demyelination in the central nervous system due to an abnormal accumulation of microtubules in the cytoplasm and the processes on their oligodendrocytes. Demyelination is associated with electrophysiological alterations and the mutant had a progressive astrocytosis. The illness is associated with change in cytokine levels and in the expression of different nitric oxide synthase and concomitantly lipoperoxidation in several areas of the brain. However, until now there has been no detailed anatomical analysis of neurons in this mutant. The aim of this study was to analyze the dendritic morphology in the hippocampus using Golgi-Cox staining and spatial memory through Morris water maze test in young adult (3 months old) taiep rats and compare them with normal Sprague-Dawley. Our results showed that taiep rats have altered dendritic tree morphology in pyramidal neurons in the CA1 field of the hippocampus, but not in the CA3 region. These morphological changes did not produce a concomitant deficit in spatial memory acquisition or recall at this early stage of the disease. Our results suggest that impairment of dendritic morphology in the CA1 field of the hippocampus is a landmark of the pathology of this progressive multiple sclerosis model.

Environmental and genetic factors in pediatric inflammatory demyelinating diseases.

The onset of multiple sclerosis (MS) occurs in childhood in about 5% of all patients with MS. The disease in adults has a complex genetic and environmental inheritability. One of the main risk factors, also confirmed in pediatric MS, is HLA DRB1*1501 In addition to genetic factors, a large part of disease susceptibility in adults is conferred by environmental risk factors such as low vitamin D status, exposure to cigarette smoking, and remote Epstein-Barr virus (EBV) infection. In children, both exposure to cigarette smoking and prior EBV infection have been reported consistently as risk factors for MS. The role of vitamin D remains to be confirmed in this age category. Finally, although very likely critical in disease processes, few gene-environment interactions and epigenetic changes have been reported for adult and pediatric MS susceptibility. Of interest, some of the risk factors for MS have also been associated with disease course modification, such as low 25(OH) vitamin D serum levels in pediatric and adult MS. Age is also a clear disease modifier of clinical, CSF, and MRI phenotype in children with the disease. Finally, although much has yet to be unraveled regarding molecular processes at play in MS, there is a larger gap in our knowledge of genetic and environmental risk factors for pediatric neuromyelitis optica spectrum disorders and acute disseminated encephalomyelitis and only collaborative studies will answer those questions.

Association Between the Single Nucleotide Polymorphism and the Level of Aquaporin-4 Protein Expression in Han and Minority Chinese with Inflammatory Demyelinating Diseases of the Central Nervous System.

The purpose of this study was to determine whether or not aquaporin-4 (AQP4) gene mutations are related to the pathogenesis of inflammatory demyelinating diseases in the central nervous system. Polymorphisms of AQP4 exons 1-5 were determined by sequencing DNA from 67 patients with central nervous system inflammatory demyelinating diseases, including neuromyelitis optica (NMO), multiple sclerosis, recurrent or simultaneous bilateral optic neuritis, and longitudinally extensive transverse myelitis. A plasmid with the identified new missense mutation was constructed, and human embryonic kidney cells (HEK293A) were transfected with either the pEGFP-N1-AQP4-M23 vector (bearing the identified mutated cDNA sequence) or with the plasmid bearing the wild-type AQP4 gene sequence. AQP4 protein expression was analyzed in both experimental groups using Western Blot analysis following protein extraction from transfected cells. A synonymous mutation (rs1839318) was detected on exon 3, and an additional synonymous mutation was detected on the exon 2-2 (rs72557968). Most importantly, a new missense mutation was detected on exon 2-1. According to Western blot analysis, the mutated cDNA sequence yielded increased AQP4 protein expression in comparison with the wild-type cDNA sequence (P < 0.05). AQP4 gene mutations are uncommon, occurring in only 3 out of 67 patients. Although it is possible that the mutations contributed to an increased risk of inflammatory central nervous system disease in these individuals, it is unlikely that mutations are a significant contributor to most patients with NMO spectrum disorders in China.

miR-155-3p Drives the Development of Autoimmune Demyelination by Regulation of Heat Shock Protein 40.

microRNA-155 (miR-155) plays an important role in posttranscriptional gene regulation of the immune system. We and others have described miR-155 upregulation in T helper cells (Th) during the development of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. We have shown that mice in which the miR-155 host gene (MIR155HG) has been deactivated are resistant to EAE. MIR155HG produces two different miRNA strands, miR-155-5p and miR-155-3p, and miR-155-5p has been considered the only functional miR-155 form. Surprisingly, we found that miR-155-3p is also strongly upregulated in Th cells infiltrating the brain in EAE. Functional manipulation of miR-155-3p expression revealed its particular role in regulation of Th17 development. The search for miRNA-155-3p target genes highlighted transcripts of two heat shock protein 40 genes, Dnaja2 and Dnajb1. These two genes negatively regulated Th17 differentiation, leading to decreased EAE. Therefore, our findings provide new insights into a previously unknown mechanism by which miR-155-3p controls Th17 cell differentiation and autoimmune demyelination. SIGNIFICANCE STATEMENT: Multiple sclerosis (MS) is brain-specific autoimmune disease mediated by T helper (Th) cells autoreactive to myelin. The mechanisms leading to MS are not fully understood and microRNAs (miRNAs) emerge as important regulators of the process. We report that, in an MS murine model of experimental autoimmune encephalomyelitis, miR-155 controls Th cell function by an unusual mechanism involving a rare form, miR-155-3p. miR-155-3p is specifically found in brain-infiltrating myelin-autoreactive CD4(+) T cells and contributes to the development of an encephalitogenic Th17 population. miR-155-3p promotes Th17 by inhibiting two heat shock protein 40 genes, Dnaja2 and Dnajb1. Our findings indicate a unique miRNA function in the brain-infiltrating Th cells and suggest Dnaja2 and Dnajb1 as targets for intervention in autoimmune demyelination.

TNFR2 Deficiency Acts in Concert with Gut Microbiota To Precipitate Spontaneous Sex-Biased Central Nervous System Demyelinating Autoimmune Disease.

TNF-α antagonists provide benefit to patients with inflammatory autoimmune disorders such as Crohn's disease, rheumatoid arthritis, and ankylosing spondylitis. However, TNF antagonism unexplainably exacerbates CNS autoimmunity, including multiple sclerosis and neuromyelitis optica. The underlying mechanisms remain enigmatic. We demonstrate that TNFR2 deficiency results in female-biased spontaneous autoimmune CNS demyelination in myelin oligodendrocyte glycoprotein-specific 2D2 TCR transgenic mice. Disease in TNFR2(-/-) 2D2 mice was associated with CNS infiltration of T and B cells as well as increased production of myelin oligodendrocyte glycoprotein-specific IL-17, IFN-γ, and IgG2b. Attenuated disease in TNF(-/-) 2D2 mice relative to TNFR2(-/-) 2D2 mice identified distinctive roles for TNFR1 and TNFR2. Oral antibiotic treatment eliminated spontaneous autoimmunity in TNFR2(-/-) 2D2 mice to suggest role for gut microbiota. Illumina sequencing of fecal 16S rRNA identified a distinct microbiota profile in male TNFR2(-/-) 2D2 that was associated with disease protection. Akkermansia muciniphila, Sutterella sp., Oscillospira sp., Bacteroides acidifaciens, and Anaeroplasma sp. were selectively more abundant in male TNFR2(-/-) 2D2 mice. In contrast, Bacteroides sp., Bacteroides uniformis, and Parabacteroides sp. were more abundant in affected female TNFR2(-/-) 2D2 mice, suggesting a role in disease causation. Overall, TNFR2 blockade appears to disrupt commensal bacteria-host immune symbiosis to reveal autoimmune demyelination in genetically susceptible mice. Under this paradigm, microbes likely contribute to an individual's response to anti-TNF therapy. This model provides a foundation for host immune-microbiota-directed measures for the prevention and treatment of CNS-demyelinating autoimmune disorders.

Mutations in RNF216 do not cause 4H syndrome.

We comment on the recent publication by Ganos et al. [1] classifying a patient with non-specific white matter abnormalities, cerebellar atrophy, hypogonadotropic hypogonadism and absent lower median incisors as 4H syndrome. He had mutations in RNF216. Mutations in this gene cause Gordon-Holmes syndrome, distinct from 4H syndrome.

Selective accumulation of pro-inflammatory T cells in the intestine contributes to the resistance to autoimmune demyelinating disease.

Myelin-specific, pro-inflammatory TH17 cells are widely regarded as the drivers of experimental autoimmune encephalomyelitis (EAE), an animal model for Multiple sclerosis (MS). The factors, responsible for the generation and maintenance of TH17 cells as well as their participation in the pathogenic cascade leading to the demyelinating disease, have been studied extensively. However, how these harmful autoreactive cells are controlled in vivo remains unclear. By comparing TCR transgenic mice on a disease susceptible and a disease resistant genetic background, we show here that pathogenic TH17 cells are sequestered within the intestine of spontaneous EAE resistant B10.S mice. Disease resistant B10.S mice harbored higher frequencies of TH17 cells in the intestine compared to EAE susceptible SJL/J mice. Moreover, transferred TH17 cells selectively migrated to intestinal lymphoid organs of B10.S mice. The sequestration of TH17 cells in the gut was partially dependent on the gut homing receptor α4ß7-mediated adhesion to the intestine. Administration of α4ß7 blocking-antibodies increased the peripheral availability of TH17 cells, resulting in increased EAE severity after immunization in B10.S mice. Together, these results support the concept that the intestine is a check-point for controlling pathogenic, organ-specific T cells.

Accelerated repair of demyelinated CNS lesions in the absence of non-muscle myosin IIB.

The oligodendrocyte (OL), the myelinating cell of the central nervous system, undergoes dramatic changes in the organization of its cytoskeleton as it differentiates from a precursor (oligodendrocyte precursor cells) to a myelin-forming cell. These changes include an increase in its branching cell processes, a phenomenon necessary for OL to myelinate multiple axon segments. We have previously shown that levels and activity of non-muscle myosin II (NMII), a regulator of cytoskeletal contractility, decrease as a function of differentiation and that inhibition of NMII increases branching and myelination of OL in coculture with neurons. We have also found that mixed glial cell cultures derived from NMIIB knockout mice display an increase in mature myelin basic protein-expressing OL compared with wild-type cultures. We have now extended our studies to investigate the role of NMIIB ablation on myelin repair following focal demyelination by lysolecithin. To this end, we generated an oligodendrocyte-specific inducible knockout model using a Plp-driven promoter in combination with a temporally activated CRE-ER fusion protein. Our data indicate that conditional ablation of NMII in adult mouse brain, expedites lesion resolution and remyelination by Plp+ oligodendrocyte-lineage cells when compared with that observed in control brains. Taken together, these data validate the function of NMII as that of a negative regulator of OL myelination in vivo and provide a novel target for promoting myelin repair in conditions such as multiple sclerosis.

Lack of association between AQP4 polymorphisms and risk of inflammatory demyelinating disease in a Korean population.

Multiple sclerosis (MS) and neuromyelitis optica (NMO) are demyelinating autoimmune inflammatory diseases that affect the central nervous system (CNS). Previous genome-wide or candidate gene studies have suggested that genetic variants might be associated with the risk of MS or NMO. Aquaporin 4 (AQP4) is a commonly distributed water channel in astrocytes of the CNS, and its expression is decreased in NMO lesions due to astrocyte cytotoxicity. Previous studies have suggested the associations of AQP4 single nucleotide polymorphisms (SNPs) with MS and/or NMO. However, there have been few replication studies in various ethnic populations. This study, as the first of its kind performed in an Asian population, investigated associations of AQP4 SNPs with the risk of inflammatory demyelinating disease (IDD), including MS and NMO, in a Korean population. A total of seven common AQP4 SNPs were selected based on status of linkage disequilibrium (LD), and then genotyped in 178 IDD cases (79 MS and 99 NMO patients) and 237 normal controls. Statistical analyses showed no significant associations between AQP4 SNPs/haplotypes and development of IDD, including MS and NMO (P>0.05). Further replications in larger cohorts and other ethnic groups are needed.

Endogenous, or therapeutically induced, type I interferon responses differentially modulate Th1/Th17-mediated autoimmunity in the CNS.

Different viruses trigger pattern recognition receptor systems, such as Toll-like receptors or cytosolic RIG-I like helicases (RLH), and thus induce early type I interferon (IFN-I) responses. Such responses may confer protection until adaptive immunity is activated to an extent that the pathogen can be eradicated. Interestingly, the same innate immune mechanisms that are relevant for early pathogen defense have a role in ameliorating experimental autoimmune encephalomyelitis (EAE), a rodent model of human multiple sclerosis. We and others found that mice devoid of a component of the IFN-I receptor (Ifnar1(-/-)) showed significantly enhanced autoimmune disease of the central nervous system (CNS). A detailed analysis revealed that in wild-type mice IFN-I triggering of myeloid cells was instrumental in reducing brain damage. A more recent study indicated that similar to Ifnar1(-/-) mice, RLH-signaling-deficient mice showed enhanced autoimmune disease of the CNS as well. Moreover, when peripherally treated with synthetic RLH ligands wild-type animals with EAE disease showed reduced clinical scores. Under such conditions, IFN-I receptor triggering of dendritic cells had a crucial role. The therapeutic effect of treatment with RLH ligands was associated with negative regulation of Th1 and Th17 T-cell responses within the CNS. These experiments are consistent with the hypothesis that spatiotemporal conditions of, and cell types involved in, disease-ameliorating IFN-I responses differ significantly, depending on whether they were endogenously induced in the context of EAE pathogenesis within the CNS or upon therapeutic RLH triggering in the periphery. It is attractive to speculate that RLH triggering represents a new strategy to treat multiple sclerosis by stimulating endogenous immunoregulatory IFN-I responses.

[Antibody-associated diseases of the gray matter of the CNS: diagnosis and treatment]. / Antikörperassoziierte Erkrankungen der grauen Substanz des ZNS : Diagnostik und Therapie.

In the past 10 years, the diagnosis and understanding of immune-mediated diseases of the gray matter of the CNS have greatly advanced with the discovery of autoantibodies in serum and CSF of affected patients. The newly described antibodies against neuronal surface antigens, i.e., receptors, channels, and associated proteins, seem to have a direct pathogenic effect on CNS neurons. Fortunately, there is a beneficial effect of immunotherapy in many patients. The diagnosis of autoantibody-associated disease of the CNS gray matter requires the combination of a typical clinical syndrome or a characteristic paraclinical finding (MRI, CSF, histopathology) with the detection of a specific antibody. In the following, an overview will first be given of the syndromes typically associated with autoantibodies. Thereafter, the diagnosis of these syndromes is discussed, and finally, preliminary treatment recommendations are given.

IL-2 suppression of IL-12p70 by a recombinant HSV-1 expressing IL-2 induces T-cell auto-reactivity and CNS demyelination.

To evaluate the role of cellular infiltrates in CNS demyelination in immunocompetent mice, we have used a model of multiple sclerosis (MS) in which different strains of mice are infected with a recombinant HSV-1 expressing IL-2. Histologic examination of the mice infected with HSV-IL-2 demonstrates that natural killer cells, dendritic cells, B cells, and CD25 (IL-2rα) do not play any role in the HSV-IL-2-induced demyelination. T cell depletion, T cell knockout and T cell adoptive transfer experiments suggest that both CD8(+) and CD4(+) T cells contribute to HSV-IL-2-induced CNS demyelination with CD8(+) T cells being the primary inducers. In the adoptive transfer studies, all of the transferred T cells irrespective of their CD25 status at the time of transfer were positive for expression of FoxP3 and depletion of FoxP3 blocked CNS demyelination by HSV-IL-2. The expression levels of IL-12p35 relative to IL-12p40 differed in BM-derived macrophages infected with HSV-IL-2 from those infected with wild-type HSV-1. HSV-IL-2-induced demyelination was blocked by injecting HSV-IL-2-infected mice with IL-12p70 DNA. This study demonstrates that suppression of the IL-12p70 function of macrophages by IL-2 causes T cells to become auto-aggressive. Interruption of this immunoregulatory axis results in demyelination of the optic nerve, the spinal cord and the brain by autoreactive T cells in the HSV-IL-2 mouse model of MS.

Microglial cystatin F expression is a sensitive indicator for ongoing demyelination with concurrent remyelination.

Demyelination coincides with numerous changes of gene expression in the central nervous system (CNS). Cystatin F, which is a papain-like lysosomal cysteine proteinase inhibitor that is normally expressed by immune cells and not in the brain, is massively induced in the CNS during acute demyelination. We found that microglia, which are monocyte/macrophage-lineage cells in the CNS, express cystatin F only during demyelination. By using several demyelinating animal models and the spinal cord tissues from multiple sclerosis (MS) patients, we examined spatiotemporal expression pattern of cystatin F by in situ hybridization and immunohistochemistry. We found that the timing of cystatin F induction matches with ongoing demyelination, and the places with cystatin F expression overlapped with the remyelinating area. Most interestingly, cystatin F induction ceased in chronic demyelination, in which remyelinating ability was lost. These findings demonstrate that the expression of cystatin F indicates the occurrence of ongoing demyelination/remyelination and the absence of cystatin F expression indicates the cessation of remyelination in the demyelinating area.

Interferon-γ inhibits central nervous system myelination through both STAT1-dependent and STAT1-independent pathways.

The immune cytokine interferon-gamma (IFN-gamma) plays a crucial role in immune-mediated demyelinating diseases such as multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). Our previous studies have shown that enforced expression of IFN-gamma in the central nervous system (CNS) inhibits developmental myelination or remyelination in EAE demyelinated lesions. Although many of the cellular actions of IFN-gamma result from its activation of the signal transducer and activator of transcription 1 (STAT1) pathway, recent studies have shown that STAT1-independent pathways regulate some facets of IFN-gamma biology. In this study, we dissected the role ofSTAT1-dependent and STAT1-independent pathways in IFN-gamma-induced hypomyelination using a genetic approach. We found that the induction of STAT1-dependent, IFN-gamma-responsive genes in response to this cytokine was abolished in the CNS of STAT1 null mice. Moreover, STAT1 deletion diminished oligodendrocyte loss, reduction of myelinated axons, and the inflammatory response in the CNS of transgenic mice that ectopically expressed IFN-gamma in the CNS. Nevertheless, IFN-gamma-induced reduction of myelin sheath thickness in the CNS of these mice was not altered by STAT1 deletion. Collectively, these data demonstrate that both STAT1-dependent and STAT1-independent pathways are involved in the detrimental effects of IFN-gamma on the myelination process.

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.