Acute Demyelinating Lesions Research Articles

Myelin oligodendrocyte glycoprotein antibody‐associated disorders: An overview

AbstractIn recent years, there is growing evidence of associations between antibodies against myelin oligodendrocyte glycoprotein (MOG) and several phenotypes of acute inflammatory demyelinating diseases such as acute disseminated encephalomyelitis (ADEM), optic neuritis, brainstem, and cerebral cortical encephalitis, called MOG antibody associated disorders (MOGAD). Monophasic course is known in about half of cases especially in pediatric onset ADEM and optic neuritis, mainly in cases with transient positivity of MOG antibody. Pathological features of MOGAD are considered as acute demyelinating lesions with CD4 dominant cell infiltrations, the deposition of humoral immunity, perivascular inflammation and perivenous demyelination, which is distinct from multiple sclerosis. Now the diagnosis of MOGAD is based on the international panel criteria of MOGAD launched in 2023, which the diagnostic frameworks are three parts, including MOGAD‐specific clinical features, MOG antibody positivity, and the exclusion of other diseases. The prognosis of MOGAD patients is considered relatively mild, but the problem is refractory relapsing cases. For its prevention, there are no approved drugs, but oral tapering corticosteroids, immunosuppressants such as azathioprine and mycophenolic mofetil, rituximab, and the maintenance intravenous immunoglobulin are recommended, and now there are a few clinical trials of promising biological drugs already approved in other neurological disorders.

STING-Triggered CNS Inflammation in Human Neurodegenerative Diseases.

Some neurodegenerative diseases have an element of neuroinflammation that is triggered by viral nucleic acids, resulting in the generation of type I interferons. In the cGAS-STING pathway, microbial and host-derived DNA bind and activate the DNA sensor cGAS, and the resulting cyclic dinucleotide, 2'3-cGAMP, binds to a critical adaptor protein, stimulator of interferon genes (STING), which leads to activation of downstream pathway components. However, there is limited work demonstrating the activation of the cGAS-STING pathway in human neurodegenerative diseases. Post-mortem CNS tissue from donors with multiple sclerosis (n = 4), Alzheimer's disease (n = 6), Parkinson's disease (n = 3), amyotrophic lateral sclerosis (n = 3) and non-neurodegenerative controls (n = 11) were screened by immunohistochemistry for STING and relevant protein aggregates (e.g., amyloid-β, α-synuclein, TDP-43). Human brain endothelial cells were cultured and stimulated with the STING agonist palmitic acid (1-400 μM) and assessed for mitochondrial stress (release of mitochondrial DNA into cytosol, increased oxygen consumption), downstream regulator factors, TBK-1/pIRF3 and inflammatory biomarker interferon-β release and changes in ICAM-1 integrin expression. In neurodegenerative brain diseases, elevated STING protein was observed mainly in brain endothelial cells and neurons, compared to non-neurodegenerative control tissues where STING protein staining was weaker. Interestingly, a higher STING presence was associated with toxic protein aggregates (e.g., in neurons). Similarly high STING protein levels were observed within acute demyelinating lesions in multiple sclerosis subjects. To understand non-microbial/metabolic stress activation of the cGAS-STING pathway, brain endothelial cells were treated with palmitic acid. This evoked mitochondrial respiratory stress up to a ~2.5-fold increase in cellular oxygen consumption. Palmitic acid induced a statistically significant increase in cytosolic DNA leakage from endothelial cell mitochondria (Mander's coefficient; p < 0.05) and a significant increase in TBK-1, phosphorylated transcription factor IFN regulatory factor 3, cGAS and cell surface ICAM. In addition, a dose response in the secretion of interferon-β was observed, but it failed to reach statistical significance. The histological evidence shows that the common cGAS-STING pathway appears to be activated in endothelial and neural cells in all four neurodegenerative diseases examined. Together with the in vitro data, this suggests that the STING pathway might be activated via perturbation of mitochondrial stress and DNA leakage, resulting in downstream neuroinflammation; hence, this pathway may be a target for future STING therapeutics.

Quantitative T1 mapping detects blood–brain barrier breakdown in apparently non-enhancing multiple sclerosis lesions

ObjectivesThe disruption of the blood–brain barrier (BBB) is a key and early feature in the pathogenesis of demyelinating multiple sclerosis (MS) lesions and has been neuropathologically demonstrated in both active and chronic plaques. The local overt BBB disruption in acute demyelinating lesions is captured as signal hyperintensity in post-contrast T1-weighted images because of the contrast-related shortening of the T1 relaxation time. On the contrary, the subtle BBB disruption in chronic lesions is not visible at conventional radiological evaluation but it might be of clinical relevance. Indeed, persistent, subtle BBB leakage might be linked to low-grade inflammation and plaque evolution. Here we hypothesised that 3D Quantitative Transient-state Imaging (QTI) was able to reveal and measure T1 shortening (ΔT1) reflecting small amounts of contrast media leakage in apparently non-enhancing lesions (ANELs). Materials and methodsThirty-four patients with relapsing remitting MS were included in the study. All patients underwent a 3 T MRI exam of the brain including conventional sequences and QTI acquisitions (1.1 mm isotropic voxel) performed both before and after contrast media administration. For each patient, a ΔT1 map was obtained via voxel-wise subtraction of pre- and post- contrast QTI-derived T1 maps. ΔT1 values measured in ANELs were compared with those recorded in enhancing lesions and in the normal appearing white matter. A reference distribution of ΔT1 in the white matter was obtained from datasets acquired in 10 non-MS patients with unrevealing MR imaging. ResultsMean ΔT1 in ANELs (57.45 ± 48.27 ms) was significantly lower than in enhancing lesions (297.71 ± 177.52 ms; p < 0. 0001) and higher than in the normal appearing white matter (36.57 ± 10.53 ms; p < 0.005). Fifty-two percent of ANELs exhibited ΔT1 higher than those observed in the white matter of non-MS patients. ConclusionsQTI-derived quantitative ΔT1 mapping enabled to measure contrast-related T1 shortening in ANELs. ANELs exhibiting ΔT1 values that deviate from the reference distribution in non-MS patients may indicate persistent, subtle, BBB disruption. Access to this information may be proved useful to better characterise pathology and objectively monitor disease activity and response to therapy.

Clinical and MRI characteristics of multiple sclerosis in Iranian Children and Adolescents.

To determine the clinical and MRI characteristics of multiple sclerosis (MS) in the children and adolescents. In this cross-sectional study, information of 95 MS patients was obtained from the Iranian MS registry. Disease characteristics and imaging data were collected using medical records. Ninety-five patients including 64 female and 31 male subjects with mean age of 13.97±2.4 years (range, 8-18) years were enrolled. The most frequent signs and symptoms were ophthalmic symptoms (n=61, 64.2%), brainstem signs (n=44, 46.3%), cerebellar signs (n=32, 33.6%) and pyramidal signs (n=26, 27.3%). Blurred vision (n=21, 34.4%) was the most common ophthalmic symptom and ataxia (n=24, 75%) the most prevalent cerebellar sign. The most common brainstem signs/symptoms were motor symptoms and vertigo (each n=14, 31.8%) and the most common pyramidal sign/symptom was right upper monoparesis (n=14, 23.3%). Active demyelinating lesions were reported in brain MRI of all patients, mostly appeared as periventricular (n=91, 95.8%) and pericallosal (n=55, 57.9%) lesions. Acute demyelinating spinal lesions were presented in 38 patients (51.3%) with a prominent involvement of the cervical spine (n=33, 86.8%). In our study, the most frequent signs and symptoms were eye symptoms, brainstem signs, cerebellar signs and pyramidal signs, respectively. Moreover, our results showed that MRI plays a critical role in the diagnostic evaluation of MS in children with presence of brain lesions in all patients and spinal lesion in a considerable portion of patients.

A CASE OF COMBINED CENTRAL AND PERIPHERAL DEMYELINATION IN A PATIENT WITH PEDIATRIC MULTIPLE SCLEROSIS AFTER SARS-COV-2 VACCINATION

We present a case of combined central and peripheral demyelination in a patient with pediatric multiple sclerosis after the first dose of ChAdOx1-S (Chimpanzee Adenovirus Oxford 1) vaccination. The patient presented with ascending flaccid quadriparesis with respiratory failure that required mechanical ventilation. The lumbar puncture revealed albuminocytological dissociation, was negative for presence of JCV (John Cunningham Virus) in the CSF (Cerebrospinal Fluid) and ruled out other infections. A few days later he developed anisocoria and multiple new enlarging acute demyelinating lesions in the brain MRI (Magnetic Resonance Imaging). He was treated with intravenous immunoglobulin, corticosteroids and plasma exchange with gradual improvement. All other diseases were excluded via MR Spectroscopy, MR Angiography and serum and CSF laboratory investigations. Seven months later, the patient is under intense physiotherapy and is improving every day.

COVID-19 and Clinically Isolated Syndrome: Coincidence or Causative Link? A 12-Month Follow-Up Case Report

A 35-year-old female with positive anamnesis of COVID-19 infection presented with a seven-day history of headache along with tingling and numbness involving the right lower limb and visual disturbance on the right side of her vision. Magnetic resonance imaging (MRI) of the brain and C-spine were consistent with acute demyelinating lesions. However, the MAGNIMS criteria for a multiple sclerosis diagnosis were not met, and, subsequently, a diagnosis of clinically isolated syndrome (CIS) was made. At 12 months, the patient showed new inflammatory lesions in the right frontal lobe and at the septocallosal interface, a lesion of the right hemi-cord at C3, and subsequent development of vertigo and unsteadiness and signs consistent with a brainstem/cerebellar relapse. On the basis of clinical and radiological criteria in the 2017 McDonald criteria, a diagnosis of relapsing remitting multiple sclerosis was made.

Evolution of Neuroimaging Findings in Severe COVID-19 Patients with Initial Neurological Impairment: An Observational Study.

Background and Objectives: Cerebral complications related to the COVID-19 were documented by brain MRIs during the acute phase. The purpose of the present study was to describe the evolution of these neuroimaging findings (MRI and FDG-PET/CT) and describe the neurocognitive outcomes of these patients. Methods: During the first wave of the COVID-19 outbreak between 1 March and 31 May 2020, 112 consecutive COVID-19 patients with neurologic manifestations underwent a brain MRI at Strasbourg University hospitals. After recovery, during follow-up, of these 112 patients, 31 (initially hospitalized in intensive care units) underwent additional imaging studies (at least one brain MRI). Results: Twenty-three men (74%) and eight women (26%) with a mean age of 61 years (range: 18–79) were included. Leptomeningeal enhancement, diffuse brain microhemorrhages, acute ischemic strokes, suspicion of cerebral vasculitis, and acute inflammatory demyelinating lesions were described on the initial brain MRIs. During follow-up, the evolution of the leptomeningeal enhancement was discordant, and the cerebral microhemorrhages were stable. We observed normalization of the vessel walls in all patients suspected of cerebral vasculitis. Four patients (13%) demonstrated new complications during follow-up (ischemic strokes, hypoglossal neuritis, marked increase in the white matter FLAIR hyperintensities with presumed vascular origin, and one suspected case of cerebral vasculitis). Concerning the grey matter volumetry, we observed a loss of volume of 3.2% during an average period of approximately five months. During follow-up, the more frequent FDG-PET/CT findings were hypometabolism in temporal and insular regions. Conclusion: A minority of initially severe COVID-19 patients demonstrated new complications on their brain MRIs during follow-up after recovery.

P70S6 kinase regulates oligodendrocyte differentiation and is active in remyelinating lesions.

The p70 ribosomal S6 kinases (p70 ribosomal S6 kinase 1 and p70 ribosomal S6 kinase 2) are downstream targets of the mechanistic target of rapamycin signalling pathway. p70 ribosomal S6 kinase 1 specifically has demonstrated functions in regulating cell size in Drosophila and in insulin-sensitive cell populations in mammals. Prior studies demonstrated that the mechanistic target of the rapamycin pathway promotes oligodendrocyte differentiation and developmental myelination; however, how the immediate downstream targets of mechanistic target of rapamycin regulate these processes has not been elucidated. Here, we tested the hypothesis that p70 ribosomal S6 kinase 1 regulates oligodendrocyte differentiation during developmental myelination and remyelination processes in the CNS. We demonstrate that p70 ribosomal S6 kinase activity peaks in oligodendrocyte lineage cells at the time when they transition to myelinating oligodendrocytes during developmental myelination in the mouse spinal cord. We further show p70 ribosomal S6 kinase activity in differentiating oligodendrocytes in acute demyelinating lesions induced by lysophosphatidylcholine injection or by experimental autoimmune encephalomyelitis in mice. In demyelinated lesions, the expression of the p70 ribosomal S6 kinase target, phosphorylated S6 ribosomal protein, was transient and highest in maturing oligodendrocytes. Interestingly, we also identified p70 ribosomal S6 kinase activity in oligodendrocyte lineage cells in active multiple sclerosis lesions. Consistent with its predicted function in promoting oligodendrocyte differentiation, we demonstrate that specifically inhibiting p70 ribosomal S6 kinase 1 in cultured oligodendrocyte precursor cells significantly impairs cell lineage progression and expression of myelin basic protein. Finally, we used zebrafish to show in vivo that inhibiting p70 ribosomal S6 kinase 1 function in oligodendroglial cells reduces their differentiation and the number of myelin internodes produced. These data reveal an essential function of p70 ribosomal S6 kinase 1 in promoting oligodendrocyte differentiation during development and remyelination across multiple species.

Кратковременные и долговременные последствия коронавирусной инфекции для организма (обзор)

To date, according to the COVID-19 Data Repository by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University, there have been 250 million cases of the disease in the world, as well as 5.05 million deaths, which is almost equal to the population of the second largest city in Russia—Saint Petersburg. According to the current data, the leading countries in terms of patients infected and the number of deaths are the United States (46.4 million cases), India (34.4 million cases), Brazil (21.9 million), UK (9.3 million) and Russia (8.65). These statistics, among other factors, are attributed to high population density. The new coronavirus infection has led to a pandemic and has had physical, mental, psychological, social and economic consequences for the world population. To date, there is evidence of adverse effects of similar diseases caused by coronaviruses, namely, Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). The obtained data suggest that COVID-19 has a negative impact on various systems of the human body: respiratory, cardiovascular, immune, and nervous. Possible complications include encephalitis, toxic encephalopathy, acute demyelinating lesions. COVID-19 can also intensify pre-existing neurological conditions. The paper discusses short-term adverse health effects as well as the risk of potential long-term negative effects associated with COVID-19.

Anti-Myelin Oligodendrocyte Glycoprotein Antibody Associated Disease

Anti-myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease belongs to a new spectrum of disease entities that cause acute inflammatory demyelinating lesions in the central nervous system. MOG antibody-associated disease presents with several phenotypes including optic neuritis, myelitis, neuromyelitis optica spectrum disorder, brain stem encephalitis, acute disseminated encephalitis, and cortical encephalitis. For the diagnosis, brain magnetic resonance imaging (MRI) and cerebrospinal fluid studies are required to prove inflammatory demyelination apart from the identification of anti-MOG antibodies using cell-based assays. Immunotherapy is an effective treatment strategy to prevent relapse.

Features of Guillain — Barre syndrome associated with COVID-19 infection

In December 2019, an epidemic of coronavirus infection SARS-CoV-2 (Severe acute respiratory syndrome-related coronavirus 2) emerged in Wuhan (China). In February 2020, the World Health Organization assigned the official name to the infection caused by the new coronavirus SARS-CoV-2 — Coronavirus disease 2019 or COVID-19, which was accompanied by various neurological complications, including Guillain — Barre syndrome. The purpose — to study the features of Guillain — Barre syndrome (GBS) with a new COVID-19 infection. Results. Recently, various neurological complications of COVID-19 have been described: severe viral hemorrhagic encephalitis, toxic encephalopathy, acute demyelinating lesions, acute cerebral disorders blood circulation, etc. It is proposed to consider Guillain — Barre syndrome (GBS) a neurological complication of CO VID-19, since the main route of coronavirus infection is respiratory, and most patients with GBS describe a respiratory infection before the development of neurological symptoms. Typically, GBS develops 11-13 days after the onset of COVID-19. Recent studies have shown that GBS is one of the most common lesions of the peripheral nervous system in COVID-19. The clinical picture, as a rule, is represented by increasing flaccid tetraparesis, less often there is respiratory failure. In a pandemic, it is advisable to test patients with GBS for COVID-19 if there are no respiratory disorders, since laboratory signs of SARS-CoV-2 infection were detected in a number of patients with acute neuropathy. Given the higher demand for respiratory support in GBS patients infected with CoV-2, it is assumed that COVID-19 may trigger the progression of neurological symptoms. Diagnosing GBS in SARS-CoV-2 patients is particularly challenging because symptoms such as shortness of breath and fatigue can be misinterpreted as a consequence of SARS-CoV-2 lung damage, delaying the timely diagnosis of GBS. Conclusion. Successful GBS management depends on clinical vigilance and its early diagnosis in patients with COVID-19.

Neurological and mental disorders associated with COVID-19

The article presents a narrative review, clinical observations. Special attention is given to the pathogenesis, features of neurological manifestations and mental disorders, neurological complications in coronavirus infection, illustrated by clinical cases. Neurological disorders occur in approximately 36,4 % patients with COVID-19. Currently, severe viral hemorrhagic encephalitis, toxic encephalopathy, acute demyelinating lesions of the peripheral nervous system, stroke, behavioral and emotional disorders have been described. Despite numerous publications on the neurological pathology in COVID-19, pathogenesis, risk factors, and relation between neurological disorders and coronavirus infection remain unclear. There is a need for systematization of the accumulated data on the damage to the nervous system during the COVID-19 epidemic for clinical routine use, further development of the optimal treatment strategy and implementation of effective preventive measures.

COVID-19-associated acute disseminated encephalomyelitis (ADEM)

A 51-year-old woman with COVID-19 infection developed coma and an impaired oculocephalic response to one side. MRI of the brain demonstrated acute multifocal demyelinating lesions, and CSF testing did not identify a direct cerebral infection. High-dose steroids followed by a course of IVIG was administered, and the patient regained consciousness over the course of several weeks. As more patients reach the weeks after initial infection with COVID-19, acute disseminated encephalomyelitis should be considered a potentially treatable cause of profound encephalopathy or multifocal neurological deficits.

RNU6-1 in circulating exosomes differentiates GBM from non-neoplastic brain lesions and PCNSL but not from brain metastases.

BackgroundGlioblastoma (GBM) is the most common malignant primary brain tumor in adults. Circulating biomarkers may assist in the processes of differential diagnosis and response assessment. GBM cells release extracellular vesicles containing a subset of proteins and nucleic acids. We previously demonstrated that exosomes isolated from the serum of GBM patients had an increased expression of RNU6-1 compared to healthy subjects. In this exploratory study, we investigated the role of this small noncoding RNA as a diagnostic biomarker for GBM versus other brain lesions with some potential radiological similarities.MethodsWe analyzed the expression of RNU6-1 in circulating exosomes of GBM patients (n = 18), healthy controls (n = 30), and patients with subacute stroke (n = 30), acute/subacute hemorrhage (n = 30), acute demyelinating lesions (n = 18), brain metastases (n = 21), and primary central nervous system lymphoma (PCNSL; n = 12) using digital droplet PCR.ResultsExpression of RNU6-1 was significantly higher in GBM patients than in healthy controls (P = .002). RNU6-1 levels were also significantly higher in exosomes from GBM patients than from patients with non-neoplastic lesions (stroke [P = .05], hemorrhage [P = .01], demyelinating lesions [P = .019]) and PCNSL (P = .004). In contrast, no significant differences were found between patients with GBM and brain metastases (P = .573). Receiver operator characteristic curve analyses supported the role of this biomarker in differentiating GBM from subacute stroke, acute/subacute hemorrhage, acute demyelinating lesions, and PCNSL (P < .05), but again not from brain metastases (P = .575).ConclusionsOur data suggest that the expression of RNU6-1 in circulating exosomes could be useful for the differentiation of GBM from non-neoplastic brain lesions and PCNSL, but not from brain metastases.

Improving acute demyelinating lesion detection: which T1-weighted magnetic resonance acquisition is more sensitive to gadolinium enhancement?

Because of the need for a standardized and accurate method for detecting multiple sclerosis (MS) inflammatory activity, different magnetic resonance (MR) acquisitions should be compared in order to choose the most sensitive sequence for clinical routine. To compare the sensitivity of a T1-weighted image to a single dose of gadolinium (Gd) administration both with and without magnetization transfer to detect contrast enhancement in active demyelinating focal lesions. A sample of relapsing-remitting MS patients were prospectively examined separately by two neuroradiologists using a 1.5 Tesla scanner. The outcome parameters were focused on Gd-enhancement detection attributed to acute demyelination. All MR examinations with at least one Gd-enhancing lesion were considered positive (MR+) and each lesion was analyzed according to its size and contrast ratio. Thirty-six MR examinations were analyzed with a high inter-observer agreement for MR+ detection (k coefficient > 0.8), which was excellent for the number of Gd-enhancing lesions (0.91 T1 spin-echo (SE), 0.88 T1 magnetization transfer contrast (MTC) sequence and 0.99 magnetization-prepared rapid acquisition with gradient-echo (MPRAGE). Significantly more MR+ were reported on the T1 MTC scans, followed by the T1 SE, and MPRAGE scans. Confidently, the T1 MTC sequence demonstrated higher accuracy in the detection of Gd-enhancing lesions, followed by the T1 SE and MPRAGE sequences. Further comparisons showed that there was a statistically significant increase in the contrast ratio and area of Gd-enhancement on the T1 MTC images when compared with both the SE and MPRAGE images. Single-dose Gd T1 MTC sequence was confirmed to be the most sensitive acquisition for predicting inflammatory active lesions using a 1.5 T magnet in this sample of MS patients.

Pathologic and MRI analysis in acute atypical inflammatory demyelinating lesions.

The diagnosis of atypical inflammatory demyelinating lesions can be difficult. Brain biopsy is often required to exclude neoplasms. Moreover, the relationship between these lesions and multiple sclerosis and NMOSD is not clear. Our objectives were to describe radiological and pathological characteristics of patients with acute inflammatory demyelinating lesions. We retrospectively identified patients with brain biopsy performed for diagnostic uncertainty revealing a demyelinating lesion. A complete clinical, biological, radiological and pathological analysis was performed. Twenty patients (15 with a single lesion) were included. MRI disclosed a wide range of lesions including infiltrative lesions (40%), ring-like lesion (15%) Baló-like lesion (15%) and acute haemorrhagic leukoencephalitis (20%). In spite of a marked heterogeneity, some findings were common: a peripheral B1000 hyperintense rim (70%), a slight oedema with mild mass effect (75%) and an open-rim peripheral enhancement (75%). Histopathology revealed that all cases featured macrophages distributed throughout, extensive demyelination, axonal preservation and absence of haemorrhagic changes. In the majority of cases, macrophages were the predominant inflammatory infiltrate and astrocytes were reactive and dystrophic. Aquaporin-4 staining was systematically preserved. After a mean follow-up of 5years (1-12), 16/20 patients had a diagnosis of monophasic acute atypical inflammatory demyelinating lesion. One patient was diagnosed with MS and 3 with AQP4 negative NMOSD. Although imaging findings in patients with atypical inflammatory demyelinating lesions are heterogeneous, some common features such as peripheral DWI hyperintense rim with open-rim enhancement and absence of oedema argue in favour of a demyelinating lesion and should preclude a brain biopsy. In this context, AQP4 staining is systematically preserved and argues against an AQP4-positive NMOSD. Moreover, long-term follow-up is characterized by low recurrence rate.

CBIO-06. POTENTIAL ROLE OF RNU6 ISOLATED FROM CIRCULATING EXOSOMES AS A DIAGNOSTIC BIOMARKER FOR GLIOBLASTOMA

Glioblastomas (GBM) are highly malignant brain tumors with a poor prognosis despite intensive research and clinical effort. Circulating biomarkers for the disease would be desirable in order to allow for non-invasive tumor detection and follow-up. Recent findings show that GBM cells release microvesicles that contain a select subset of cellular proteins and RNA. Previously, we observed that exosomes isolated from serum of GBM patients had an increased expression of RNU6 (a small non-coding RNA) compared to control samples, and hence could serve as a non-invasive diagnostic biomarker for GBM. In this study, we set to investigate whether this small non-coding RNA could serve as a differential diagnostic biomarker to distinguish GBM from other brain lesions resembling GBM in neuroimaging. We analyzed the expression of RNU6 in circulating exosomes of patients with six types of brain lesions that can mimic GBM on magnetic resonance imaging (i.e. subacute stroke, acute-subacute haemorrhage, acute demyelinating lesions, abscesses, brain metastases and primary CNS lymphomas). First, we isolated the exosomes from the serum of a subset of patients (20–30 patients) with these pathological conditions using an adsorption method (Exoquick). The same was done in a similar group of healthy controls and GBM patients. Then RNU6 levels were analyzed by digital droplet PCR (ddPCR). Corroborating our previous results, we found that the expression of RNU6 was significantly higher in GBM patients than in healthy controls. In addition, RNU6 levels were significantly higher in exosomes from GBM patients than in exosomes from patients with stroke, haemorrhage or acute multiple sclerosis lesions. We are currently analyzing the data regarding the expression of RNU6 in CNS metastasis and lymphomas. Our preliminary data suggest that RNU6 could serve as a differential diagnostic biomarker for GBM patients.

Th1 cells downregulate connexin 43 gap junctions in astrocytes via microglial activation.

We previously reported early and extensive loss of astrocytic connexin 43 (Cx43) in acute demyelinating lesions of multiple sclerosis (MS) patients. Because it is widely accepted that autoimmune T cells initiate MS lesions, we hypothesized that infiltrating T cells affect Cx43 expression in astrocytes, which contributes to MS lesion formation. Primary mixed glial cell cultures were prepared from newborn mouse brains, and microglia were isolated by anti-CD11b antibody-conjugated magnetic beads. Next, we prepared astrocyte-rich cultures and astrocyte/microglia-mixed cultures. Treatment of primary mixed glial cell cultures with interferon (IFN) γ, interleukin (IL)-4, or IL-17 showed that only IFNγ or IL-17 at high concentrations reduced Cx43 protein levels. Upon treatment of astrocyte-rich cultures and astrocyte/microglia-mixed cultures with IFNγ, Cx43 mRNA/protein levels and the function of gap junctions were reduced only in astrocyte/microglia-mixed cultures. IFNγ-treated microglia-conditioned media and IL-1β, which was markedly increased in IFNγ-treated microglia-conditioned media, reduced Cx43 protein levels in astrocyte-rich cultures. Finally, we confirmed that Th1 cell-conditioned medium decreased Cx43 protein levels in mixed glial cell cultures. These findings suggest that Th1 cell-derived IFNγ activates microglia to release IL-1β that reduces Cx43 gap junctions in astrocytes. Thus, Th1-dominant inflammatory states disrupt astrocytic intercellular communication and may exacerbate MS.

Increased expression KIR4.1 potassium channel in experimental models of demyelination

Histopathological studies confirm the prominent deposition of immunoglobulins (Ig) and the complement activation in acute demyelinating lesions of multiple sclerosis (MS) patients, suggesting that, at least in a subgroup of MS patients, autoantibodies could contribute to the disease. Recently, the ATP-sensitive inward rectifying potassium channel KIR4.1 has been identified as an antibody target in a small cohort of MS patients, since anti-KIR4.1 antibodies (Abs) were found in the serum of MS patients compared to those with other neurological disorders and healthy donors.

Devic disease

More than a century after histopathologic achievements in understanding multiple sclerosis, substantial molecular progress has permitted greater understanding of disease heterogeneity. For acute demyelinating lesions, Lassmann et al.1 proposed a classification based on molecular findings from diagnostic biopsies and autopsies. The understanding of neuromyelitis optica (NMO; Devic disease) has been further advanced by the discovery of the aquaporin-4 water channel as a target of autoantibodies in more than 80% of patients with NMO.2 Koch-Witebsky criteria have been partially fulfilled in NMO, because passive transfer of purified aquaporin antibodies to rodents creates similar clinical signs and histopathology of NMO, although these do not recapitulate human disease in all aspects.3 In one study, anti-KIR 4.1 antibodies occurred in approximately 50% of patients4; this finding is of interest because the KIR 4.1 channel is expressed close to the aquaporin channel on astrocytic endfeet.