Exosomes derived from bone marrow mesenchymal stromal cells promote remyelination and reduce neuroinflammation in the demyelinating central nervous system.

Injury of oligodendrocytes (OLs) induces demyelination, and patients with neurodegenerative diseases exhibit demyelination concomitantly with neurological deficit and cognitive impairment. Oligodendrocyte progenitor cells (OPCs) are present in the adult central nervous system (CNS), and they can proliferate, differentiate, and remyelinate axons after damage. However, remyelination therapies are not in clinical use. Multiple sclerosis (MS) is a major demyelinating disease in the CNS. Mesenchymal stromal cells (MSCs) have demonstrated therapeutic promise in animal models and in clinical trials of MS. Exosomes are nanoparticles generated by nearly all cells and they mediate cell-cell communication by transferring cargo biomaterials. Here, we hypothesize that exosomes harvested from MSCs have a similar therapeutic effect on enhancement of remyelination as that of MSCs. In the present study we employed exosomes derived from rhesus monkey MSCs (MSC-Exo). Two mouse models of demyelination were employed: 1) experimental autoimmune encephalomyelitis (EAE), an animal model of MS; and 2) cuprizone (CPZ) diet model, a toxic demyelination model. MSC-Exo or PBS were intravenously injected twice a week for 4 weeks, starting on day 10 post immunization in EAE mice, or once a week for 2 weeks starting on the day of CPZ diet withdrawal. Neurological and cognitive function were tested, OPC differentiation and remyelination, neuroinflammation and the potential underlying mechanisms were investigated using immunofluorescent staining, transmission electron microscopy and Western blot. Data generated from the EAE model revealed that MSC-Exo cross the blood brain barrier (BBB) and target neural cells. Compared with the controls (p < 0.05), treatment with MSC-Exo: 1) significantly improved neurological outcome; 2) significantly increased the numbers of newly generated OLs (BrdU+/APC+) and mature OLs (APC+), and the level of myelin basic protein (MBP); 3) decreased amyloid-ß precursor protein (APP)+ density; 4) decreased neuroinflammation by increasing the M2 phenotype and decreasing the M1 phenotype of microglia, as well as their related cytokines; 5) inhibited the TLR2/IRAK1/NFκB pathway. Furthermore, we confirmed that the MSC-Exo treatment significantly improved cognitive function, promoted remyelination, increased polarization of M2 phenotype and blocked TLR2 signaling in the CPZ model. Collectively, MSC-Exo treatment promotes remyelination by both directly acting on OPCs and indirectly by acting on microglia in the demyelinating CNS. This study provides the cellular and molecular basis for this cell-free exosome therapy on remyelination and modulation of neuroinflammation in the CNS, with great potential for treatment of demyelinating and neurodegenerative disorders.

Tumefactive Demyelination Appearing as Multiple Cystic Brain Lesions.

Tumefactive demyelinating lesions (TDLs) are a rare sequelae of idiopathic inflammatory demyelinating diseases of the central nervous system. Their propensity to mimic tumor and abscess poses a diagnostic challenge for the clinician. Our case depicts TDLs causing right-hand focal sensory seizures in an otherwise healthy 35-year-old female. The differential diagnosis of metastatic disease and infection were excluded on histology. Ensuing magnetic resonance imaging of the cord, in addition to cerebral spinal fluid analysis, supported the diagnosis of idiopathic inflammatory demyelinating diseases. This case highlights the need to consider the rare diagnosis of TDL when imaging shows cystic brain lesions in an otherwise healthy young adult.

Inflammatory Demyelinating Pseudotumor With Liver Dysfunction: IgG4 Related Disease With Primary Biliary Cholangitis.

Immunoglobulin G4 related disease (IgG4-RD) is a recently recognized immune-mediated disease which is far from understanding. A case of inflammatory demyelinating pseudotumor had been confirmed as IgG4-RD according to pathology features and clinical context. Combined with liver dysfunction, IgG4 related sclerotic cholangitis was suspected. However, primary biliary cholangitis was finally diagnosed by immune marks and histopathological findings. This is the first report in which mass lesions in the brain parenchyma were caused by IgG4-RD while liver dysfunction was due to primary biliary cholangitis. The clinical features of IgG4-RD are miscellaneous, and the accumulation of case reports might enrich clinicians experience and broaden their horizons about this condition.

Myelin oligodendrocyte glycoprotein antibody-associated disease: an immunopathological study.

Conformation-sensitive antibodies against myelin oligodendrocyte glycoprotein (MOG) are detectable in patients with optic neuritis, myelitis, opticomyelitis, acute or multiphasic disseminated encephalomyelitis (ADEM/MDEM) and brainstem/cerebral cortical encephalitis, but are rarely detected in patients with prototypic multiple sclerosis. So far, there has been no systematic study on the pathological relationship between demyelinating lesions and cellular/humoral immunity in MOG antibody-associated disease. Furthermore, it is unclear whether the pathomechanisms of MOG antibody-mediated demyelination are similar to the demyelination patterns of multiple sclerosis, neuromyelitis optica spectrum disorders (NMOSD) with AQP4 antibody, or ADEM. In this study, we immunohistochemically analysed biopsied brain tissues from 11 patients with MOG antibody-associated disease and other inflammatory demyelinating diseases. Patient median onset age was 29 years (range 9-64), and the median interval from attack to biopsy was 1 month (range 0.5-96). The clinical diagnoses were ADEM (n = 2), MDEM (n = 1), multiple brain lesions without encephalopathy (n = 3), leukoencephalopathy (n = 3) and cortical encephalitis (n = 2). All these cases had multiple/extensive lesions on MRI and were oligoclonal IgG band-negative. Most demyelinating lesions in 10 of 11 cases showed a perivenous demyelinating pattern previously reported in ADEM (153/167 lesions) and a fusion pattern (11/167 lesions) mainly in the cortico-medullary junctions and white matter, and only three lesions in two cases showed confluent demyelinated plaques. In addition, 60 of 167 demyelinating lesions (mainly in the early phase) showed MOG-dominant myelin loss, but relatively preserved oligodendrocytes, which were distinct from those of AQP4 antibody-positive NMOSD exhibiting myelin-associated glycoprotein-dominant oligodendrogliopathy. In MOG antibody-associated diseases, MOG-laden macrophages were found in the perivascular spaces and demyelinating lesions, and infiltrated cells were abundant surrounding multiple blood vessels in and around the demyelinating lesions, mainly consisting of macrophages (CD68; 1814 ± 1188 cells/mm2), B cells (CD20; 468 ± 817 cells/mm2), and T cells (CD3; 2286 ± 1951 cells/mm2), with CD4-dominance (CD4+ versus CD8+; 1281 ± 1196 cells/mm2 versus 851 ± 762 cells/mm2, P < 0.01). Humoral immunity, evidenced by perivascular deposits of activated complements and immunoglobulins, was occasionally observed in some MOG antibody-associated demyelinating lesions, and the frequency was much lower than that in AQP4 antibody-positive NMOSD. Subpial lesions with perivenous demyelination were observed in both ADEM and cortical encephalitis. Our study suggests that ADEM-like perivenous inflammatory demyelination with MOG-dominant myelin loss is a characteristic finding of MOG antibody-associated disease regardless of whether the diagnostic criteria of ADEM are met. These pathological features are clearly different from those of multiple sclerosis and AQP4 antibody-positive NMOSD, suggesting an independent autoimmune demyelinating disease entity.

MOG-IgG-associated demyelination: focus on atypical features, brain histopathology and concomitant autoimmunity.

INTRODUCTION: Antibodies to myelin oligodendrocyte glycoprotein (MOG) have been demonstrated in patients with optic neuritis (ON), encephalitis and myelitis. OBJECTIVE: To describe the clinical and paraclinical features in patients with MOG-associated demyelination, focusing on unusual cases, brain biopsy and concomitant autoimmunity. METHODS: A single centre retrospective observational case series, analysing demographic, clinical, laboratory, histopathology and radiological data from MOG- positive patients. RESULTS: We identified 20 adults. The male/female ratio was 1.5. Mean age at onset was 31.6 years and mean disease duration was 7.5 years. The most frequent presentation was myelitis (45%), followed by ON (30%). One case had simultaneous myelitis and ON. Two patients had a cortical syndrome, 1 patient had an encephalopathic presentation and 1 cryptogenic focal epilepsy. Anti-neutrophil cytoplasmic antibodies (ANCA) were found in 3 cases, while 1 patient had an antibody to glutamic acid decarboxylase (GAD). Brain biopsy was performed in 2 patients. Relapsing course was identified in 60% of patients. We also discuss 3 cases with atypical features, brain histopathology and concomitant autoimmunity. CONCLUSION: MOG- associated demyelination represents a new disease entity. Unusual cases are reported, expanding the disease spectrum. Elucidating this further should be the focus of prospective studies.

Pseudotumoral demyelinating lesions: diagnostic approach and long-term outcome.

PURPOSE OF REVIEW: To review the clinical findings, differential diagnosis, treatment and outcome of pseudotumoral demyelinating lesions including tumefactive demyelination and Baló's concentric sclerosis. RECENT FINDINGS: MRI findings, such as dynamic restricted diffusion changes at the edge of pseudotumoral lesions help to discriminate atypical demyelination from key differential diagnoses, and together with histopathological data, indicate that tissue hypoxia may be important aetiologically. CT-PET imaging can help to distinguish pseudotumoral lesions from high-grade tumours. Although most patients with pseudotumoral lesions have or later develop multiple sclerosis, a proportion will experience a monophasic course or be diagnosed with neuromyelitis optica spectrum disorders (NMOSD), myelin oligodendrocyte glycoprotein (MOG) antibody-associated demyelination or acute disseminated encephalomyelitis (ADEM). Many patients with pseudotumoral demyelinating lesions have a favourable prognosis. SUMMARY: Not all patients with pseudotumoral lesions require a brain biopsy but close follow-up of biopsied and nonbiopsied lesions is indicated once a diagnosis is established. Testing for AQP4-IgG and MOG-IgG is recommended when a pseudotumoral demyelinating lesion is identified. In the absence of large, prospective studies, it seems reasonable that patients with pseudotumoral lesions who fulfil multiple sclerosis diagnostic criteria are treated with multiple sclerosis therapies.

An unusual case of anti-MOG CNS demyelination with concomitant mild anti-NMDAR encephalitis.

We report the case of a patient who presented with progressive unsteadiness and narcoleptic attacks followed by behavioral change and psychosis, without visual disturbances or seizures. MRI revealed multiple areas of fluid attenuation inversion recovery (FLAIR) high-intensity lesions involving the cerebellum, brainstem, thalamus and third ventricular peri-ependymal region consistent with demyelination. Both the serum myelin oligodendrocyte glycoprotein-antibodies (MOG-Abs) and cerebral spinal fluid (CSF) anti-N-methyl-d-as-partate receptor (NMDAR) antibodies were positive using transfected cell based assays. The patient presented simultaneously with symptoms of MOG antibody disease and anti-NMDAR encephalitis, an unusual clinical scenario, indicating the co-existence of the two disorders.

Myelin phagocytosis by astrocytes after myelin damage promotes lesion pathology.

Astrocytes are key players in the pathology of multiple sclerosis and can assume beneficial and detrimental roles during lesion development. The triggers and timing of the different astroglial responses in acute lesions remain unclear. Astrocytes in acute multiple sclerosis lesions have been shown previously to contain myelin debris, although its significance has not been examined. We hypothesized that myelin phagocytosis by astrocytes is an early event during lesion formation and leads to astroglial immune responses. We examined multiple sclerosis lesions and other central nervous system pathologies with prominent myelin injury, namely, progressive multifocal leukoencephalopathy, metachromatic leukodystrophy and subacute infarct. In all conditions, we found that myelin debris was present in most astrocytes at sites of acute myelin breakdown, indicating that astroglial myelin phagocytosis is an early and prominent feature. Functionally, myelin debris was taken up by astrocytes through receptor-mediated endocytosis and resulted in astroglial NF-κB activation and secretion of chemokines. These in vitro results in rats were validated in human disease where myelin-positive hypertrophic astrocytes showed increased nuclear localization of NF-κB and elevated chemokine expression compared to myelin-negative, reactive astrocytes. Thus, our data suggest that myelin uptake is an early response of astrocytes in diseases with prominent myelin injury that results in recruitment of immune cells. This first line response of astrocytes to myelin injury may exert beneficial or detrimental effects on the lesion pathology, depending on the inflammatory context. Modulating this response might be of therapeutic relevance in multiple sclerosis and other demyelinating conditions.

Balo's concentric lesions with concurrent features of Schilder's disease in relapsing multiple sclerosis: neuropathological findings

Atypical inflammatory demyelinating syndromes are rare neurological diseases that differ from multiple sclerosis (MS), owing to unusual clinicoradiological and pathological findings, and poor responses to treatment. The distinction between them and the criteria for their diagnoses are poorly defined due to the lack of advanced research studies. Balo's concentric sclerosis (BCS) and Schilder's disease (SD) are two of these syndromes and can present as monophasic or in association with chronic MS. Both variants are difficult to distinguish when they present in acute stages. We describe an autopsy case of middle-aged female with a chronic history of MS newly relapsed with atypical demyelinating lesions, which showed concurrent features of BCS and SD. We also describe the neuropathological findings, and discuss the overlapping features between these two variants.

Oligodendrocyte death results in immune-mediated CNS demyelination.

Although multiple sclerosis is a common neurological disorder, the origin of the autoimmune response against myelin, which is the characteristic feature of the disease, remains unclear. To investigate whether oligodendrocyte death could cause this autoimmune response, we examined the oligodendrocyte ablation Plp1-CreER(T);ROSA26-eGFP-DTA (DTA) mouse model. Approximately 30 weeks after recovering from oligodendrocyte loss and demyelination, DTA mice develop a fatal secondary disease characterized by extensive myelin and axonal loss. Strikingly, late-onset disease was associated with increased numbers of T lymphocytes in the CNS and myelin oligodendrocyte glycoprotein (MOG)-specific T cells in lymphoid organs. Transfer of T cells derived from DTA mice to naive recipients resulted in neurological defects that correlated with CNS white matter inflammation. Furthermore, immune tolerization against MOG ameliorated symptoms. Overall, these data indicate that oligodendrocyte death is sufficient to trigger an adaptive autoimmune response against myelin, suggesting that a similar process can occur in the pathogenesis of multiple sclerosis.

Clinical and MRI phenotype of children with MOG antibodies.

OBJECTIVE: To investigate the clinical and magnetic resonance imaging (MRI) features of anti-myelin oligodendrocyte glycoprotein (MOG) antibody-seropositive pediatric demyelinating syndromes. METHODS: Serum samples collected from 74 children with suspected demyelinating disorders whom were being followed at Massachusetts General Hospital were incubated with control green fluorescent protein (GFP)- and MOG-GFP-transfected Jurkat cell clones. The binding ratios were calculated using flow cytometry. Using statistical analyses, we compared the demographic, clinical and radiological features in our seropositive and seronegative patients. RESULTS: We found that 13 out of 74 (17.5%) patients were seropositive for MOG. The MOG-seropositive patients were younger than the seronegative patients (p = 0.049). No single disease category predominated among the seropositive patients, nor was one group more likely to have a polyphasic course. There were two out of four neuromyelitis optica (NMO) patients who had MOG antibodies; both were seronegative for aquaporin -4 (AQP4) antibodies. One had monophasic disease and the other had frequent relapses. There was a bimodal distribution of the MOG-seropositive patients by age at onset, with a distinct younger group (4-8 years) having a high prevalence of encephalopathy and an older group (13-18 years), whom presented almost exclusively with optic neuritis. MRI analysis demonstrated the absence of corpus callosum lesions in the seropositive patients (p = 0.012). The annualized relapse rate (ARR) and the Expanded Disability Status Scale (EDSS) results at 2 years did not differ between the seropositive and seronegative patients. CONCLUSION: MOG antibodies are found across a variety of pediatric demyelinating syndromes having some distinct clinical and MRI features.

NG2-proteoglycan-dependent contributions of oligodendrocyte progenitors and myeloid cells to myelin damage and repair.

BACKGROUND: The NG2 proteoglycan is expressed by several cell types in demyelinated lesions and has important effects on the biology of these cells. Here we determine the cell-type-specific roles of NG2 in the oligodendrocyte progenitor cell (OPC) and myeloid cell contributions to demyelination and remyelination. METHODS: We have used Cre-Lox technology to dissect the cell-type-specific contributions of NG2 to myelin damage and repair. Demyelination is induced by microinjection of 1 % lysolecithin into the spinal cord white matter of control, OPC-specific NG2-null (OPC-NG2ko), and myeloid-specific NG2-null (My-NG2ko) mice. The status of OPCs, myeloid cells, axons, and myelin is assessed by light, immunofluorescence, confocal, and electron microscopy. RESULTS: In OPC-NG2ko mice 1 week after lysolecithin injection, the OPC mitotic index is reduced by 40 %, resulting in 25 % fewer OPCs at 1 week and a 28 % decrease in mature oligodendrocytes at 6 weeks post-injury. The initial demyelinated lesion size is not affected in OPC-NG2ko mice, but lesion repair is delayed by reduced production of oligodendrocytes. In contrast, both the initial extent of demyelination and the kinetics of lesion repair are decreased in My-NG2ko mice. Surprisingly, the OPC mitotic index at 1 week post-injury is also reduced (by 48 %) in My-NG2ko mice, leading to a 35 % decrease in OPCs at 1 week and a subsequent 34 % reduction in mature oligodendrocytes at 6 weeks post-injury. Clearance of myelin debris is also reduced by 40 % in My-NG2ko mice. Deficits in myelination detected by immunostaining for myelin basic protein are confirmed by toluidine blue staining and by electron microscopy. In addition to reduced myelin repair, fewer axons are found in 6-week lesions in both OPC-NG2ko and My-NG2ko mice, emphasizing the importance of myelination for neuron survival. CONCLUSIONS: Reduced generation of OPCs and oligodendrocytes in OPC-NG2ko mice correlates with reduced myelin repair. Diminished demyelination in My-NG2ko mice may stem from a reduction (approximately 70 %) in myeloid cell recruitment to lesions. Reduced macrophage/microglia numbers may then result in decreased myelin repair via diminished clearance of myelin debris and reduced stimulatory effects on OPCs.

Lesser-known myelin-related disorders: focal tumour-like demyelinating lesions.

INTRODUCTION: Focal tumour-like demyelinating lesions are defined as solitary demyelinating lesions with a diameter greater than 2 cm. In imaging studies, these lesions may mimic a neoplasm or brain abscess; as a result, invasive diagnostic and therapeutic measures may be performed that will in some cases increase morbidity. Our aim was to analyse and characterise these lesions according to their clinical, radiological, and pathological characteristics, and this data in addition to our literature review will contribute to a better understanding of these lesions. METHODS: This descriptive study includes 5 cases with pathological diagnoses. We provide subject characteristics gathered through reviewing their clinical, radiology, and pathology reports. RESULTS: Patients' ages ranged from 12 to 60 years; 3 patients were female. The time delay between symptom onset and hospital admission was 3 to 120 days. Clinical manifestations were diverse and dependent on the location of the lesion, pyramidal signs were found in 80% of patients, there were no clinical or radiological signs of spinal cord involvement, and follow-up times ranged from 1 to 15 years. CONCLUSION: Brain biopsy is the gold standard for the diagnosis of demyelinating tumour-like lesions; however, their clinical features, along with several magnetic resonance imaging features such as open ring enhancement, venular enhancement, the presence of glutamate in spectroscopy, and others, may be sufficient to differentiate neoplastic lesions from focal tumour-like demyelinating lesions.

Multiple sclerosis, solitary sclerosis or something else?

BACKGROUND: Inflammatory demyelinating diseases of the central nervous system represent a wide spectrum of entities and their classification cannot currently be regarded complete. OBJECTIVE: Our aim is to describe a series of patients presenting with progressive myelopathy associated to a single demyelinating lesion of the spinal cord. METHODS: We identified the patients affected by chronic progressive spinal cord dysfunction related to a single spinal cord lesion not satisfying the diagnostic criteria for any of the currently defined diseases. RESULTS: Seven females and one male were included. The median age at onset of symptoms was 53 years (range 42-68) and the median follow-up was 8 years (range 5-12). Brain and spinal magnetic resonance imaging (MRI) scans detected only one single, circumscribed, T2 hyperintense, non-longitudinally extensive lesion at level of cervico-medullary junction or cervical cord, in the absence of Gadolinium enhancement or swelling. Cerebrospinal fluid (CSF) examination displayed neither oligoclonal bands nor raised IgG index. A response to immunosuppressive agents was observed in some of the patients. Serial control brain and spinal MRI did not reveal accumulation of new lesions. CONCLUSION: New entities or variants should be included among the inflammatory demyelinating diseases of the central nervous system, and their characterization may have relevant prognostic and treatment implications.

Clinical features and sera anti-aquaporin 4 antibody positivity in patients with demyelinating disorders of the central nervous system from Tianjin, China.

AIMS: To investigate the clinical characteristics and sera anti-aquaporin 4 (AQP4) antibody positivity in patients with inflammatory demyelinating disorders (IDDs) of the central nervous system (CNS) in Tianjin, China. METHODS: We retrospectively evaluated 234 patients with IDDs including neuromyelitis optica (NMO), recurrent optic neuritis (rON), longitudinally extensive transverse myelitis (LETM), clinically isolated syndrome (CIS), and multiple sclerosis (MS) groups. Sera from 217 patients were determined for AQP4-Ab. The clinical characteristics and sera anti-AQP4 positivity were compared. RESULTS: The IDDS comprised 63 MS, 51 NMO, 56 LETM, 10 rON, and 54 CIS. Compared with MS, NMO had a higher frequency of occurrence in women, intractable hiccup and nausea (IHN), medullospinal lesion, longitudinally extensive spinal cord lesions (LESCL) and bilateral ON, disease onset at a later age, and worsening residual disability. AQP4-Ab-positive rates were 84.1% and 69% in NMO and NMO spectrum disorders (NMOSD), respectively, whereas it was undetectable in all of the MS sera samples. CONCLUSIONS: We comprehensively contrast the distinct clinical features of MS, NMO, and NMOSD in our center. A sensitive AQP4-Ab assay is necessary for the early diagnosis of NMOSD in our patients. Neither medullospinal lesion nor IHN is unique in NMO.

[Role of microglia in inflammatory demyelination lesion in the central nervous system].

In the lesion of experimental autoimmune encephalomyelitis (EAE), two different kinds of macrophages are activated: microglia derived macrophages (MiDM) and monocytes derived macrophages (MDM). These macrophages elicit different functions in the development of demyelination lesions in EAE. MDMs are infiltrated in the acute phase of EAE, and initiate demyelination at the nodes of Ranvier. On the other hands, MiDM always activated at the peak and the chronic stage of the disease. These macrophages express totally different cytokines at different time course of the disease: MDM are activated in the early stage of the disease and express genes that are mainly related to inflammation, while MiDM are activated at the peak and recovery stage and express genes that are related to homeostasis. Our findings provide the idea to develop new therapeutic strategy not only for demyelinating disease but also other neurological diseases with neuro-inflammation.

[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.