Validating a minipig model of reversible cerebral demyelination using human diagnostic modalities and electron microscopy.

BACKGROUND: Inflammatory demyelinating diseases of the central nervous system, such as multiple sclerosis, are significant sources of morbidity in young adults despite therapeutic advances. Current murine models of remyelination have limited applicability due to the low white matter content of their brains, which restricts the spatial resolution of diagnostic imaging. Large animal models might be more suitable but pose significant technological, ethical and logistical challenges. METHODS: We induced targeted cerebral demyelinating lesions by serially repeated injections of lysophosphatidylcholine in the minipig brain. Lesions were amenable to follow-up using the same clinical imaging modalities (3T magnetic resonance imaging, 11C-PIB positron emission tomography) and standard histopathology protocols as for human diagnostics (myelin, glia and neuronal cell markers), as well as electron microscopy (EM), to compare against biopsy data from two patients. FINDINGS: We demonstrate controlled, clinically unapparent, reversible and multimodally trackable brain white matter demyelination in a large animal model. De-/remyelination dynamics were slower than reported for rodent models and paralleled by a degree of secondary axonal pathology. Regression modelling of ultrastructural parameters (g-ratio, axon thickness) predicted EM features of cerebral de- and remyelination in human data. INTERPRETATION: We validated our minipig model of demyelinating brain diseases by employing human diagnostic tools and comparing it with biopsy data from patients with cerebral demyelination. FUNDING: This work was supported by the DFG under Germany's Excellence Strategy within the framework of the Munich Cluster for Systems Neurology (EXC 2145 SyNergy, ID 390857198) and TRR 274/1 2020, 408885537 (projects B03 and Z01).

Remyelination by surviving oligodendrocytes is inefficient in the inflamed mammalian cortex.

In multiple sclerosis, an inflammatory attack results in myelin loss, which can be partially reversed by remyelination. Recent studies suggest that mature oligodendrocytes could contribute to remyelination by generating new myelin. Here, we show that in a mouse model of cortical multiple sclerosis pathology, surviving oligodendrocytes can indeed extend new proximal processes but rarely generate new myelin internodes. Furthermore, drugs that boost myelin recovery by targeting oligodendrocyte precursor cells did not enhance this alternate mode of myelin regeneration. These data indicate that the contribution of surviving oligodendrocytes to myelin recovery in the inflamed mammalian CNS is minor and inhibited by distinct remyelination brakes.

Deep-learning online EEG decoding brain-computer interface using error-related potentials recorded with a consumer-grade headset.

Objective.Brain-computer interfaces (BCIs) allow subjects with sensorimotor disability to interact with the environment. Non-invasive BCIs relying on EEG signals such as event-related potentials (ERPs) have been established as a reliable compromise between spatio-temporal resolution and patient impact, but limitations due to portability and versatility preclude their broad application. Here we describe a deep-learning augmented error-related potential (ErrP) discriminating BCI using a consumer-grade portable headset EEG, the Emotiv EPOC+.Approach.We recorded and discriminated ErrPs offline and online from 14 subjects during a visual feedback task.Main results:We achieved online discrimination accuracies of up to 81%, comparable to those obtained with professional 32/64-channel EEG devices via deep-learning using either a generative-adversarial network or an intrinsic-mode function augmentation of the training data and minimalistic computing resources.Significance.Our BCI model has the potential of expanding the spectrum of BCIs to more portable, artificial intelligence-enhanced, efficient interfaces accelerating the routine deployment of these devices outside the controlled environment of a scientific laboratory.

Case Series: Acute Hemorrhagic Encephalomyelitis After SARS-CoV-2 Vaccination.

We present three cases fulfilling diagnostic criteria of hemorrhagic variants of acute disseminated encephalomyelitis (acute hemorrhagic encephalomyelitis, AHEM) occurring within 9 days after the first shot of ChAdOx1 nCoV-19. AHEM was diagnosed using magnetic resonance imaging, cerebrospinal fluid analysis and brain biopsy in one case. The close temporal association with the vaccination, the immune-related nature of the disease as well as the lack of other canonical precipitating factors suggested that AHEM was a vaccine-related adverse effect. We believe that AHEM might reflect a novel COVID-19 vaccine-related adverse event for which physicians should be vigilant and sensitized.

CD20 monoclonal antibodies for the treatment of multiple sclerosis: up-to-date.

INTRODUCTION: Featuring demyelination and axonal degeneration, multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system representing a prominent cause of disability in young adults. The recently established therapeutic targeting of B cells in MS patients using CD20 monoclonal antibodies (CD20-mAbs) not only profoundly suppresses inflammatory disease activity but also materializes as the first treatment approach against disability accumulation in a subset of patients with primary progressive MS. AREAS COVERED: We will review current concepts regarding the immunopathology of B cells as well as results of clinical trials with CD20-mAbs in MS, from the murine-human chimeras rituximab and ublituximab to their increasingly humanized counterparts ocrelizumab and ofatumumab. We conducted a literature search using PubMed, clinicaltrials.gov, and clinicaltrialsregister.eu. We will focus on studies emphasizing the effectiveness of these mAbs in reducing MS disease activity and progression, long-term safety, optimal dosage and maintenance regimens. Lastly, we will turn to outstanding questions regarding anti-CD20 therapy in MS. EXPERT OPINION: CD20-mAbs could become first-line drugs in selected patients with highly active MS and already constitute an option for PPMS. Future studies could evaluate whether administration regimens currently in use can be optimized, while registry data could shed light on risk versus benefits on the long run, considering immunosenescence and a potentially increased risk of malignancies and infections in an aging population.

Impaired path integration in mice with disrupted grid cell firing.

Path integration (PI) is a highly conserved, self-motion-based navigation strategy. Since the discovery of grid cells in the medial entorhinal cortex, neurophysiological data and computational models have suggested that these neurons serve PI. However, more direct empirical evidence supporting this hypothesis has been missing due to a lack of selective manipulations of grid cell activity and suitable behavioral assessments. Here we report that selective disruption of grid cell activity in mice can be achieved by removing NMDA glutamate receptors from the retro-hippocampal region and that disrupted grid cell firing accounts for impaired PI performance. Notably, the genetic manipulation did not affect the activity of other spatially selective cells in the medial entorhinal cortex and the hippocampus. By directly linking grid cell activity to PI, these results contribute to a better understanding of how grid cells support navigation and spatial memory.