Enfermedad asociada a anticuerpos contra la glicoproteína de mielina de oligodendrocitos / Myelin oligodendrocyte glycoprotein antibody disease

Introducción: La enfermedad asociada a anticuerpos contra la glicoproteína de mielina del oligodendrocito (MOGAD, por sus siglas en inglés) es una entidad clínica recientemente identificada. La frecuencia de presentación del MOGAD es desconocida, pero se considera baja con respecto a otras enfermedades inflamatorias desmielinizantes. Materiales y métodos: Revisión narrativa de la literatura. Resultados: Las manifestaciones clínicas de esta condición son heterogéneas e incluyen neuritis óptica, mielitis, desmielinización multifocal del sistema nervioso central y encefalitis cortical. Se han descrito algunos hallazgos radiológicos que aumentan la sospecha diagnóstica, como el realce perineural del nervio óptico, el signo de la H en el cordón espinal y la resolución de lesiones T2 con el tiempo. El diagnóstico se basa en la detección de inmunoglobulinas G específicas contra MOG, en el contexto clínico adecuado. El tratamiento consiste en manejo de los ataques agudos con dosis altas de corticoides y en algunos casos se deberá considerar la inmunosupresión crónica, considerar la inmunosupresión crónica en pacientes con recurrencia o con discapacidad severa residual tras el primer evento. Conclusiones: En esta revisión narrativa se resumen los aspectos clave con respecto a la fisiopatología, las manifestaciones, el diagnóstico y el tratamiento de la MOGAD.

Introduction: The disease associated with antibodies against the myelin oligodendrocyte glycoprotein (MOGAD) is a recently identified clinical entity, with unknown frequency, but is considered low compared to other demyelinating inflammatory diseases. Materials And Methods: Narrative review. Results: The clinical manifestations are heterogeneous, ranging from optic neuritis or myelitis to multi-focal CNS demyelination or cortical encephalitis. There have been described characteristic MRI features that increase the diagnostic suspicion, such as perineural optic nerve enhancement, spinal cord H-sign or T2-lesion resolution over time. The diagnosis is based on the detection of specific G- immunoglobulins against MOG, in the suggestive clinical context. Acute treatment is based on high dose steroids and maintenance treatment is generally reserved for relapsing cases or patients with severe residual disability after the first attack. Conclusions: In this narrative review, fundamental aspects of pathophysiology, clinical and radiological manifestations, diagnosis and treatment of MOGAD are discussed.

Regulation of neuronal repair and regeneration through inhibition of oligodendrocyte myelin glycoprotein (OMgp).

The inability of neural cells to regenerate themselves after an injury represents the major difference between neural cells and other cells of the body. Various factors are responsible for this, as the expression of myelin-derived inhibitors of axonal outgrowth such as neurite outgrowth inhibitor (Nogo), myelin-associated growth factor, and oligodendrocyte-myelin glycoprotein (OMgp) hinder the central nervous system (CNS) axons to recover properly and inhibit the neuron regeneration. The patient with spinal cord injury can even permanently lose their function due to the inability of axons to regenerate. However, their role in neural regeneration in vivo is not known completely. During the study, we found that once CNS gets injured, the axon growth inhibitor OMgp binds to the Nogo-66 Receptor 1 (NgR1) which in turn restricts the normal functioning of CNS. Considering the OMgp as the target protein, two flavonoid libraries (curcumin and piperine) were screened against it to get potential inhibitors. The effectiveness of the ligands was first screened by three-tier structure-based virtual screening by Glide, Schrödinger. Based on the docking score, the best-docked compounds were taken for absorption, distribution, metabolism, and excretion analysis and the top two complexes from each library were chosen for simulation studies. Flavonoid ligands showed a much better binding affinity when compared with already known inhibitors Riluzole and Minocycline. To date, no natural inhibitors are known for OMgp. Hence, this study can provide novel insight for upcoming research in this area. Communicated by Ramaswamy H. Sarma.

Oligodendrocyte myelin glycoprotein as a novel target for pathogenic autoimmunity in the CNS.

Autoimmune disorders of the central nervous system (CNS) comprise a broad spectrum of clinical entities. The stratification of patients based on the recognized autoantigen is of great importance for therapy optimization and for concepts of pathogenicity, but for most of these patients, the actual target of their autoimmune response is unknown. Here we investigated oligodendrocyte myelin glycoprotein (OMGP) as autoimmune target, because OMGP is expressed specifically in the CNS and there on oligodendrocytes and neurons. Using a stringent cell-based assay, we detected autoantibodies to OMGP in serum of 8/352 patients with multiple sclerosis, 1/28 children with acute disseminated encephalomyelitis and unexpectedly, also in one patient with psychosis, but in none of 114 healthy controls. Since OMGP is GPI-anchored, we validated its recognition also in GPI-anchored form. The autoantibodies to OMGP were largely IgG1 with a contribution of IgG4, indicating cognate T cell help. We found high levels of soluble OMGP in human spinal fluid, presumably due to shedding of the GPI-linked OMGP. Analyzing the pathogenic relevance of autoimmunity to OMGP in an animal model, we found that OMGP-specific T cells induce a novel type of experimental autoimmune encephalomyelitis dominated by meningitis above the cortical convexities. This unusual localization may be directed by intrathecal uptake and presentation of OMGP by meningeal phagocytes. Together, OMGP-directed autoimmunity provides a new element of heterogeneity, helping to improve the stratification of patients for diagnostic and therapeutic purposes.

InCl3 mediated heteroarylation of indoles and their derivatization via CH activation strategy: Discovery of 2-(1H-indol-3-yl)-quinoxaline derivatives as a new class of PDE4B selective inhibitors for arthritis and/or multiple sclerosis.

A new class of PDE4 inhibitors were designed and synthesized via the InCl3 mediated heteroarylation of indoles and their further derivatization through the Pd(II)-catalyzed CH activation strategy. This effort allowed us to discover a series of 2-(1H-indol-3-yl)-quinoxaline based inhibitors possessing PDE4B selectivity over PDE4D and PDE4C. One of these compounds i.e. 3b (PDE4B IC50 = 0.39 ±â€¯0.13 µM with ∼27 and > 250 fold selectivity for PDE4B over PDE4D and C, respectively) showed effects in Zebrafish experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis when dosed at 3, 10 and 30 mg/kg intraperitoneally. Indeed, it halted the progression of the disease across all these doses tested. At an intraperitoneal dose of 30 mg/kg the compound 3b showed promising effects in adjuvant induced arthritic rats. The compound reduced paw volume, inflammation and pannus formation (in the knee joints) as well as pro-inflammatory gene expression/mRNA levels significantly in arthritic rats. Moreover, this compound was found to be selective towards PDE4 over other families of PDEs in vitro and safe when tested for its probable toxicity (e.g. teratogenicity, hepatotoxicity and cardiotoxicity) in Zebrafish.

[Extended optic neuropathy with myelin oligodendrocyte glycoprotein antibodies]. / Le cas clinique du mois. Neuropathie optique étendue en présence d'anticorps «anti-myelin oligodendrocyte glycoprotein¼.

The discovery of autoantibodies targeting aquaporin-4 (AQP4) of astrocytes has improved the understanding and management of Neuromyelitis Optica Syndrome Disorders (NMO-SD), previously considered as a variant of multiple sclerosis. Later, the detection of MOG IgG1 antibodies, directed against an oligodendrocyte myelin glycoprotein, made it possible to distinguish pathologies with different clinical and prognostic particularities, then helping the clinician in his diagnostic and therapeutic approach. This clinical case aims to feature the clinical differences, prognosis and therapeutic solutions of these pathologies.

La découverte d'auto-anticorps ciblant l'aquaporine-4 (AQP4) des astrocytes a permis d'avancer dans la compréhension et la prise en charge du spectre des maladies de la neuromyélite optique (NMO-SD), antérieurement considérée comme une variante proche de la sclérose en plaques. Plus tard, la mise en évidence des anticorps MOG IgG1, dirigés contre une protéine de la myéline oligodendrocytaire, a permis de distinguer des pathologies avec des particularités cliniques et pronostiques différentes, pouvant aider le clinicien dans sa démarche diagnostique et thérapeutique. Ce cas clinique permet de détailler les différences cliniques et pronostiques ainsi que les solutions thérapeutiques de ces pathologies.

The nod-like receptor, Nlrp12, plays an anti-inflammatory role in experimental autoimmune encephalomyelitis.

BACKGROUND: Multiple sclerosis (MS) is an organ-specific autoimmune disease resulting in demyelinating plaques throughout the central nervous system. In MS, the exact role of microglia remains unknown. On one hand, they can present antigens, skew T cell responses, and upregulate the expression of pro-inflammatory molecules. On the other hand, microglia may express anti-inflammatory molecules and inhibit inflammation. Microglia express a wide variety of immune receptors such as nod-like receptors (NLRs). NLRs are intracellular receptors capable of regulating both innate and adaptive immune responses. Among NLRs, Nlrp12 is largely expressed in cells of myeloid origins. It plays a role in immune inflammatory responses by negatively regulating the nuclear factor-kappa B (NF-κB) pathway. Thus, we hypothesize that Nlrp12 suppresses inflammation and ameliorates the course of MS. METHODS: We used experimental autoimmune encephalomyelitis (EAE), a well-characterized mouse model of MS. EAE was induced in wild-type (WT) and Nlrp12 (-/-) mice with myelin oligodendrocyte glycoprotein (MOG):complete Freud's adjuvant (CFA). The spinal cords of healthy and immunized mice were extracted for immunofluorescence and pro-inflammatory gene analysis. Primary murine cortical microglia cell cultures of WT and Nlrp12 (-/-) were prepared with cortices of 1-day-old pups. The cells were stimulated with lipopolysaccharide (LPS) and analyzed for the expression of pro-inflammatory genes as well as pro-inflammatory molecule secretions. RESULTS: Over the course of 9 weeks, the Nlrp12 (-/-) mice demonstrated increased severity in the disease state, where they developed the disease earlier and reached significantly higher clinical scores compared to the WT mice. The spinal cords of immunized WT mice relative to healthy WT mice revealed a significant increase in Nlrp12 messenger ribonucleic acid (mRNA) expression at 1, 3, and 5 weeks post injection. A significant increase in the expression of pro-inflammatory genes Ccr5, Cox2, and IL-1ß was found in the spinal cords of the Nlrp12 (-/-) mice relative to the WT mice (P < 0.05). A significant increase in the level of gliosis was observed in the spinal cords of the Nlrp12 (-/-) mice compared to the WT mice after 9 weeks of disease (P < 0.05). Primary Nlrp12 (-/-) microglia cells demonstrated a significant increase in inducible nitric oxide synthase (iNOS) expression (P < 0.05) and secreted significantly (P < 0.05) more tumor necrosis factor alpha (TNFα), interleukin-6 (IL-6), and nitric oxide (NO). CONCLUSION: Nlrp12 plays a protective role by suppressing inflammation during the development of EAE. The absence of Nlrp12 results in an increased inflammatory response.

Increased migration of olfactory ensheathing cells secreting the Nogo receptor ectodomain over inhibitory substrates and lesioned spinal cord.

Olfactory ensheathing cell (OEC) transplantation emerged some years ago as a promising therapeutic strategy to repair injured spinal cord. However, inhibitory molecules are present for long periods of time in lesioned spinal cord, inhibiting both OEC migration and axonal regrowth. Two families of these molecules, chondroitin sulphate proteoglycans (CSPG) and myelin-derived inhibitors (MAIs), are able to trigger inhibitory responses in lesioned axons. Mounting evidence suggests that OEC migration is inhibited by myelin. Here we demonstrate that OEC migration is largely inhibited by CSPGs and that inhibition can be overcome by the bacterial enzyme Chondroitinase ABC. In parallel, we have generated a stable OEC cell line overexpressing the Nogo receptor (NgR) ectodomain to reduce MAI-associated inhibition in vitro and in vivo. Results indicate that engineered cells migrate longer distances than unmodified OECs over myelin or oligodendrocyte-myelin glycoprotein (OMgp)-coated substrates. In addition, they also show improved migration in lesioned spinal cord. Our results provide new insights toward the improvement of the mechanisms of action and optimization of OEC-based cell therapy for spinal cord lesion.

Confirmed enterovirus encephalitis with associated steroid-responsive acute disseminated encephalomyelitis: an overlapping infection and inflammation syndrome.

BACKGROUND: Inflammatory disorders of the central nervous system have generally been separated into infectious or immune-mediated aetiologies. However, there are emerging examples of confirmed infectious viral infection of the brain followed by secondary inflammation or autoimmunity that is amenable to immune suppressive therapies. METHODS: We report four children with confirmed enterovirus encephalitis (CSF enterovirus PCR positivity), who had MRI evidence of inflammatory demyelination compatible with ADEM. RESULTS: Two patients had a monophasic course, whereas two had a biphasic course. Serum myelin oligodendrocyte glycoprotein antibodies were negative in two tested patients, although all patients had mirrored CSF and serum oligoclonal bands. All four patients only improved with introduction of immune therapy (corticosteroids in three, corticosteroid and intravenous immunoglobulin in one). CONCLUSION: These cases provide a further example of the overlap between CNS infection and immune mediated CNS disease. Randomised controlled trials investigating immune therapies in encephalitis are required.

Altered expression of myelin-associated inhibitors and their receptors after traumatic brain injury in the mouse.

PURPOSE: When central nervous system axons are injured, regeneration is partly inhibited by myelin-associated inhibitors (MAIs). Following traumatic brain injury (TBI) in the rat, pharmacological neutralisation of the MAIs Nogo-A and myelin-associated glycoprotein (MAG) resulted in improved functional outcome. In contrast, genetic or pharmacological neutralization of the MAI receptors Nogo-66 receptor 1 (NgR1) or paired-immunoglobulin like receptor-B (PirB) showed an unaltered or impaired outcome following TBI in mice. The aim of the present study was thus to evaluate the MAI expression levels following TBI in mice. METHODS: Quantitative reverse transcriptase PCR (qRT-PCR) was used to measure total RNA isolated from brains of young adult male C57BL/6 mice at one, three or seven days following controlled cortical impact TBI or sham injury. Hippocampal and neocortical tissue ipsi- and contralateral to the injury was analyzed for Nogo-A, oligodendrocyte-myelin glycoprotein (OMgp), MAG, and the MAI receptors PirB and NgR1, including its co-receptor Lingo1. RESULTS: Compared to sham-injured controls, PirB neocortical expression was significantly upregulated at one day and NgR1 expression downregulated at seven days post-TBI. In the hippocampus, transcriptional upregulation was observed in Nogo-A (one day post-injury), MAG and PirB at seven days post-injury. In contrast, the hippocampal transcripts of NgR1 and Lingo1 were decreased at seven days post-injury. The expression of OMgp was unaltered at all time points post-injury. CONCLUSION: These results suggest that early dynamic changes in MAI gene expression occur following TBI in the mouse, particularly in the hippocampus, which may play an inhibitory role for post-injury regeneration and plasticity.

LOTUS suppresses axon growth inhibition by blocking interaction between Nogo receptor-1 and all four types of its ligand.

Axon growth inhibitors such as Nogo proteins, myelin-associated glycoprotein (MAG), oligodendrocyte myelin glycoprotein (OMgp), and B lymphocyte stimulator (BLyS) commonly bind to Nogo receptor-1 (NgR1), leading to enormous restriction of functional recovery after damage to the adult central nervous system. Recently, we found that lateral olfactory tract usher substance (LOTUS) antagonizes NgR1-mediated Nogo signaling. However, whether LOTUS exerts antagonism of NgR1 when bound by the other three ligands has not been determined. Overexpression of LOTUS together with NgR1 in COS7 cells blocked the binding of MAG, OMgp, and BLyS to NgR1. In cultured dorsal root ganglion neurons in which endogenous LOTUS is only weakly expressed, overexpression of LOTUS suppressed growth cone collapse and neurite outgrowth inhibition induced by these three NgR1 ligands. LOTUS suppressed NgR1 ligand-induced growth cone collapse in cultured olfactory bulb neurons, which endogenously express LOTUS. Growth cone collapse was induced by NgR1 ligands in lotus-deficient mice. These data suggest that LOTUS functions as a potent endogenous antagonist for NgR1 when bound by all four known NgR1 ligands, raising the possibility that LOTUS may protect neurons from NgR1-mediated axonal growth inhibition and thereby may be useful for promoting neuronal regeneration as a potent inhibitor of NgR1.

Myelin-associated inhibitors in axonal growth after CNS injury.

There are multiple barriers to axonal growth after CNS injury. Myelin-associated inhibitors represent one group of barriers extrinsic to the injured neurons. Nogo, MAG and OMgp are three prototypical myelin inhibitors that signal through multiple neuronal receptors to exert growth inhibition. Targeting myelin inhibition alone modulates the compensatory sprouting of uninjured axons but the effect on the regeneration of injured axons is limited. Meanwhile, modulating sprouting, a naturally occurring repair mechanism, may be a more attainable therapeutic goal for promoting functional repair after CNS injury in the near term.

SCIRR39 promotes differentiation of oligodendrocyte precursor cells and regulates expression of myelin-associated inhibitory factors.

SCIRR39 is an identified upregulated gene in rat primary neuron injury and/or regeneration process. However, roles of SCIRR39 in the regeneration of central nervous system (CNS) injury are still largely unexplored. Using real-time quantitative PCR and Western blotting, SCIRR39 expression was detected in oligodendrocyte precursor cells (OPCs) and oligodendrocytes. Moreover, the results from cell proliferation and cell cycle indicated that SCIRR39 inhibited OPCs proliferation and induced cell cycle arrest in G0/G1 and G2/M phases. Importantly, SCIRR39 positively regulated OPC differentiation and the expression of myelin basic protein. We also examined the effect of SCIRR39 on expression of myelin-associated inhibitory factors, including myelin-associated glycoprotein (MAG), oligodendrocyte myelin glycoprotein (OMgp), and Nogo A. Nogo A level was markedly regulated by SCIRR39 overexpression or knockdown in oligodendrocytes and cortical neurons co-cultures, while the expression of MAG and OMgp was not obviously changed by SCIRR39 overexpression or knockdown. Taken together, our results indicate the important role of SCIRR39 either in OPC differentiation or in axon myelination, and may provide a new therapeutic target for the treatment of CNS injury.