scholarly journals Reduction of AMPA receptor activity on mature oligodendrocytes attenuates loss of myelinated axons in autoimmune neuroinflammation

2020 ◽  
Vol 6 (2) ◽  
pp. eaax5936
Author(s):  
Kirsten S. Evonuk ◽  
Ryan E. Doyle ◽  
Carson E. Moseley ◽  
Ian M. Thornell ◽  
Keith Adler ◽  
...  
Keyword(s):  
Ampa Receptor ◽  
Calcium Influx ◽  
White Matter Lesions ◽  
Data Link ◽  
Autoimmune Encephalomyelitis ◽  
Myelinated Axons ◽  
Neuroprotective Strategy ◽  
Genetic Deletion ◽  
Myelin Degradation

Glutamate dysregulation occurs in multiple sclerosis (MS), but whether excitotoxic mechanisms in mature oligodendrocytes contribute to demyelination and axonal injury is unexplored. Although current treatments modulate the immune system, long-term disability ensues, highlighting the need for neuroprotection. Glutamate is elevated before T2-visible white matter lesions appear in MS. We previously reported that myelin-reactive T cells provoke microglia to release glutamate from the system xc− transporter promoting myelin degradation in experimental autoimmune encephalomyelitis (EAE). Here, we explore the target for glutamate in mature oligodendrocytes. Most glutamate-stimulated calcium influx into oligodendrocyte somas is AMPA receptor (AMPAR)–mediated, and genetic deletion of AMPAR subunit GluA4 decreased intracellular calcium responses. Inducible deletion of GluA4 on mature oligodendrocytes attenuated EAE and loss of myelinated axons was selectively reduced compared to unmyelinated axons. These data link AMPAR signaling in mature oligodendrocytes to the pathophysiology of myelinated axons, demonstrating glutamate regulation as a potential neuroprotective strategy in MS.

scholarly journals Arctigenin Exerts Neuroprotective Effect By Ameliorating Cortical Activities in Experimental Autoimmune Encephalomyelitis in Vivo

2021 ◽  
Author(s):  
Liangpeng Wei ◽  
Zhenyi Xue ◽  
Baihui Lan ◽  
Shiyang Yuan ◽  
Yuanyuan Li ◽  
...  
Keyword(s):  
Experimental Autoimmune Encephalomyelitis ◽  
Ampa Receptor ◽  
Calcium Influx ◽  
Neuroprotective Effect ◽  
Network Activity ◽  
Autoimmune Encephalomyelitis ◽  
Preclinical Stage ◽  
Eae Model ◽  
Experimental Autoimmune

Abstract Background Multiple sclerosis (MS) is a chronic disease in the central nervous system (CNS), characterized by inflammatory cells invade into the brain and the spinal cord. Among a bulk of different MS models, the rodent model of experimental autoimmune encephalomyelitis (EAE) is the most widely used and best understood. Arctigenin, a botanical extract from Arctium lappa, is reported to exhibit pharmacological properties including anti-inflammation and neuroprotection. However, the effects of Arctigenin on neural activity attacked by inflammation in MS are still unclear.Methods Female C57BL/6 mice were expressed by an ultra-sensitive protein calcium sensor GCamp6f in somatosensory cortex neurons through stereotaxic virus injection. Then we induced EAE model in mice with myelin oligodendrocyte glycoprotein (MOG) peptide (35-55) and used two-photon calcium imaging to chronically observe cortical activity in vivo throughout the disease progression. Besides, we performed whole-cell electrophysiological recording to determine the frequency of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated spontaneous excitatory postsynaptic current (sEPSC) in cortical brain slices of preclinical EAE mice.ResultsHere we found added hyperactive cells, calcium influx, network connectivity and synchronization, mainly at preclinical stage of EAE model. Besides, more silent cells and decreased calcium influx and reduced network synchronization accompanied by a compensatory rise in functional connectivity were found at the remission stage. Arctigenin treatment not only restricted inordinate individually neural spiking, calcium influx and network activity at preclinical stage, but also restored neuronal activity and communication at remission stage. In addition, we confirmed that the frequency of AMPA receptor-sEPSC was also increased at preclinical stage and can be blunted by Arctigenin. Conclusions Our findings suggest that excitotoxicity resulted from calcium influx is involved in EAE at preclinical stage. Moreover, Arctigenin exerts neuroprotective effect by limiting hyperactivity at preclinical stage and ameliorates EAE symptoms, indicating Arctigenin could be a potential therapeutic drug for neuroprotection in MS-related neuropsychological disorders.

scholarly journals Implication of Contactins in Demyelinating Pathologies

Life ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 51
Author(s):  
Ilias Kalafatakis ◽  
Maria Savvaki ◽  
Theodora Velona ◽  
Domna Karagogeos
Keyword(s):  
Nervous System ◽  
White Matter ◽  
Cell Adhesion Molecules ◽  
White Matter Lesions ◽  
Myelinated Axon ◽  
Immunoglobulin Superfamily ◽  
Proper Function ◽  
Myelinated Axons ◽  
And Function

Demyelinating pathologies comprise of a variety of conditions where either central or peripheral myelin is attacked, resulting in white matter lesions and neurodegeneration. Myelinated axons are organized into molecularly distinct domains, and this segregation is crucial for their proper function. These defined domains are differentially affected at the different stages of demyelination as well as at the lesion and perilesion sites. Among the main players in myelinated axon organization are proteins of the contactin (CNTN) group of the immunoglobulin superfamily (IgSF) of cell adhesion molecules, namely Contactin-1 and Contactin-2 (CNTN1, CNTN2). The two contactins perform their functions through intermolecular interactions, which are crucial for myelinated axon integrity and functionality. In this review, we focus on the implication of these two molecules as well as their interactors in demyelinating pathologies in humans. At first, we describe the organization and function of myelinated axons in the central (CNS) and the peripheral (PNS) nervous system, further analyzing the role of CNTN1 and CNTN2 as well as their interactors in myelination. In the last section, studies showing the correlation of the two contactins with demyelinating pathologies are reviewed, highlighting the importance of these recognition molecules in shaping the function of the nervous system in multiple ways.

scholarly journals Axonal damage in spinal cord is associated with gray matter atrophy in sensorimotor cortex in experimental autoimmune encephalomyelitis

2019 ◽  
Vol 26 (3) ◽  
pp. 294-303 ◽  
Author(s):  
Cassandra E Meyer ◽  
Josephine L Gao ◽  
James Ying-Jie Cheng ◽  
Mandavi R Oberoi ◽  
Hadley Johnsonbaugh ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Experimental Autoimmune Encephalomyelitis ◽  
Gray Matter ◽  
Sensorimotor Cortex ◽  
Axonal Damage ◽  
Strongly Correlated ◽  
Autoimmune Encephalomyelitis ◽  
Normal Controls ◽  
Experimental Autoimmune

Background: Gray matter (GM) atrophy in brain is one of the best predictors of long-term disability in multiple sclerosis (MS), and recent findings have revealed that localized GM atrophy is associated with clinical disabilities. GM atrophy associated with each disability mapped to a distinct brain region, revealing a disability-specific atlas (DSA) of GM loss. Objective: To uncover the mechanisms underlying the development of localized GM atrophy. Methods: We used voxel-based morphometry (VBM) to evaluate localized GM atrophy and Clear Lipid-exchanged Acrylamide-hybridized Rigid Imaging-compatible Tissue-hYdrogel (CLARITY) to evaluate specific pathologies in mice with experimental autoimmune encephalomyelitis (EAE). Results: We observed extensive GM atrophy throughout the cerebral cortex, with additional foci in the thalamus and caudoputamen, in mice with EAE compared to normal controls. Next, we generated pathology-specific atlases (PSAs), voxelwise mappings of the correlation between specific pathologies and localized GM atrophy. Interestingly, axonal damage (end-bulbs and ovoids) in the spinal cord strongly correlated with GM atrophy in the sensorimotor cortex of the brain. Conclusion: The combination of VBM with CLARITY in EAE can localize GM atrophy in brain that is associated with a specific pathology in spinal cord, revealing a PSA of GM loss.

scholarly journals Long-term potentiation is independent of the C-tail of the GluA1 AMPA receptor subunit

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Javier Díaz-Alonso ◽  
Wade Morishita ◽  
Salvatore Incontro ◽  
Jeffrey Simms ◽  
Julia Holtzman ◽  
...  
Keyword(s):  
Spatial Memory ◽  
Morris Water Maze ◽  
Ampa Receptor ◽  
Water Maze ◽  
Long Term Potentiation ◽  
Receptor Subunit ◽  
Terminal Domain ◽  
Term Potentiation ◽  
Ampa Receptor Subunit

We tested the proposal that the C-terminal domain (CTD) of the AMPAR subunit GluA1 is required for LTP. We found that a knock-in mouse lacking the CTD of GluA1 expresses normal LTP and spatial memory, assayed by the Morris water maze. Our results support a model in which LTP generates synaptic slots, which capture passively diffusing AMPARs.

scholarly journals Long-Term Provision of Acidified Drinking Water Fails to Influence Autoimmune Diabetes and Encephalomyelitis

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Sundararajan Jayaraman ◽  
Arathi Jayaraman
Keyword(s):  
Drinking Water ◽  
Autoimmune Diseases ◽  
Autoimmune Diabetes ◽  
Nod Mice ◽  
Autoimmune Encephalomyelitis ◽  
Gastrointestinal Pathogen ◽  
Onset Of Diabetes ◽  
Partial Blocking

Induction of autoimmune diseases is predisposed by background genetics and influenced by environmental factors including diet and infections. Since consumption of acidified drinking water leads to eradication of gastrointestinal pathogens in animals, we tested whether it may also influence the development of autoimmune diseases. The frequency of spontaneously occurring type 1 diabetes in female NOD mice that were maintained on acidified drinking water by the vendor did not alter after switching to neutral water in our facility. In addition, experimentally induced autoimmune encephalomyelitis was also unaffected by the pH of the drinking water. Interestingly, administration of complete Freund’s adjuvant alone or emulsified with a neuronal peptide to induce neurodegenerative disease during the prediabetic stage completely prevented the onset of diabetes regardless of the pH of the drinking water. However, exposure to microbial products later in life had only a partial blocking effect on diabetes induction, which was also not influenced by the ionic content of the drinking water. Taken together, these data indicate that the onset of autoimmune diseases is not influenced by the gastrointestinal pathogen-depleting treatment, acidified drinking water. Thus, administration of acidic drinking water does not appear to be an option for treating autoimmune diseases.

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