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Cell Reports Jun 2024Oligodendrocyte death is common in aging and neurodegenerative disease. In these conditions, dying oligodendrocytes must be efficiently removed to allow remyelination...
Oligodendrocyte death is common in aging and neurodegenerative disease. In these conditions, dying oligodendrocytes must be efficiently removed to allow remyelination and to prevent a feedforward degenerative cascade. Removal of this cellular debris is thought to primarily be carried out by resident microglia. To investigate the cellular dynamics underlying how microglia do this, we use a single-cell cortical demyelination model combined with longitudinal intravital imaging of dual-labeled transgenic mice. Following phagocytosis, single microglia clear the targeted oligodendrocyte and its myelin sheaths in one day via a precise, rapid, and stereotyped sequence. Deletion of the fractalkine receptor, CX3CR1, delays the microglial phagocytosis of the cell soma but has no effect on clearance of myelin sheaths. Unexpectedly, deletion of the phosphatidylserine receptor, MERTK, has no effect on oligodendrocyte or myelin sheath clearance. Thus, separate molecular signals are used to detect, engage, and clear distinct sub-compartments of dying oligodendrocytes to maintain tissue homeostasis.
PubMed: 38935500
DOI: 10.1016/j.celrep.2024.114385 -
Revista de Neurologia Jul 2024The XVI Post-ECTRIMS meeting took place in Seville on 20 and 21 October 2023. This meeting was attended by neurologists specialising in multiple sclerosis (MS) from... (Review)
Review
The XVI Post-ECTRIMS meeting took place in Seville on 20 and 21 October 2023. This meeting was attended by neurologists specialising in multiple sclerosis (MS) from Spain, who shared a summary of the most interesting innovations at the ECTRIMS congress, which had taken place in Milan the previous week. The aim of this article is to summarise new developments related to the pathogenesis, diagnosis and prognosis of MS. The contributions of innate immunity and central nervous system resident cells, including macrophages and microglia in MS pathophysiology and as therapeutic targets were discussed. Compartmentalised intrathecal inflammation was recognised as central to understanding the progression of MS, and the relationship between inflammatory infiltrates and disease progression was highlighted. Perspectives in demyelinating pathologies were reviewed, focusing on neuromyelitis optica and myelin oligodendrocyte glycoprotein antibody-associated disease, highlighting their pathophysiological and diagnostic differences compared to MS. Advances in neuroimaging were also discussed, and especially the analysis of active chronic lesions, such as paramagnetic rim lesions. In the absence of clinical improvements in trials of remyelinating treatments, methodological strategies to optimise the design of future studies were proposed. Breakthroughs in detecting the prodromal phase of MS, the use of biomarkers in body fluids to assess activity, progression and treatment response, and research on progression independent of flares were addressed. The need to define criteria for radiologically isolated syndrome and to clarify the concept was also discussed.
Topics: Humans; Multiple Sclerosis; Congresses as Topic
PubMed: 38934946
DOI: 10.33588/rn.7901.2024170 -
Neural Regeneration Research Jun 2024Spinal cord injury is an intractable traumatic injury. The most common hurdles faced during spinal cord injury are failure of axonal regrowth and reconnection to target...
Spinal cord injury is an intractable traumatic injury. The most common hurdles faced during spinal cord injury are failure of axonal regrowth and reconnection to target sites. These also tend to be the most challenging issues in spinal cord injury. As spinal cord injury progresses to the chronic phase, lost motor and sensory functions are not recovered. Several reasons may be attributed to the failure of recovery from chronic spinal cord injury. These include factors that inhibit axonal growth such as activated astrocytes, chondroitin sulfate proteoglycan, myelin-associated proteins, inflammatory microglia, and fibroblasts that accumulate at lesion sites. Skeletal muscle atrophy due to denervation is another chronic and detrimental spinal cord injury-specific condition. Although several intervention strategies based on multiple outlooks have been attempted for treating spinal cord injury, few approaches have been successful. To treat chronic spinal cord injury, neural cells or tissue substitutes may need to be supplied in the cavity area to enable possible axonal growth. Additionally, stimulating axonal growth activity by extrinsic factors is extremely important and essential for maintaining the remaining host neurons and transplanted neurons. This review focuses on pharmacotherapeutic approaches using small compounds and proteins to enable axonal growth in chronic spinal cord injury. This review presents some of these candidates that have shown promising outcomes in basic research (in vivo animal studies) and clinical trials: AA-NgR(310)ecto-Fc (AXER-204), fasudil, phosphatase and tensin homolog protein (PTEN) antagonist peptide 4, chondroitinase ABC, intracellular sigma peptide, (-)-epigallocatechin gallate, matrine, acteoside, pyrvate kinase M2, diosgenin, granulocyte-colony stimulating factor, and fampridine-sustained release. Although the current situation suggests that drug-based therapies to recover function in chronic spinal cord injury are limited, potential candidates have been identified through basic research, and these candidates may be subjects of clinical studies in the future. Moreover, cocktail therapy comprising drugs with varied underlying mechanisms may be effective in treating the refractory status of chronic spinal cord injury.
PubMed: 38934397
DOI: 10.4103/NRR.NRR-D-24-00176 -
Neural Regeneration Research Jun 2024Mature oligodendrocytes form myelin sheaths that are crucial for the Insulation of axons and efficient signal transmission in the central nervous system. Recent evidence...
Mature oligodendrocytes form myelin sheaths that are crucial for the Insulation of axons and efficient signal transmission in the central nervous system. Recent evidence has challenged the classical view of the functionally static mature oligodendrocyte and revealed a gamut of dynamic functions such as the ability to modulate neuronal circuitry and provide metabolic support to axons. Despite the recognition of potential heterogeneity in mature oligodendrocyte function, a comprehensive summary of mature oligodendrocyte diversity is lacking. We delve into early 20th-century studies by Robertson and Río-Hortega that laid the foundation for the modern identification of regional and morphological heterogeneity in mature oligodendrocytes. Indeed, recent morphologic and functional studies call into question the long-assumed homogeneity of mature oligodendrocyte function through the identification of distinct subtypes with varying myelination preferences. Furthermore, modern molecular investigations, employing techniques such as single cell/nucleus RNA sequencing, consistently unveil at least six mature oligodendrocyte subpopulations in the human central nervous system that are highly transcriptomically diverse and vary with central nervous system region. Age and disease related mature oligodendrocyte variation denotes the impact of pathological conditions such as multiple sclerosis, Alzheimer's disease, and psychiatric disorders. Nevertheless, caution is warranted when subclassifying mature oligodendrocytes because of the simplification needed to make conclusions about cell identity from temporally confined investigations. Future studies leveraging advanced techniques like spatial transcriptomics and single-cell proteomics promise a more nuanced understanding of mature oligodendrocyte heterogeneity. Such research avenues that precisely evaluate mature oligodendrocyte heterogeneity with care to understand the mitigating influence of species, sex, central nervous system region, age, and disease, hold promise for the development of therapeutic interventions targeting varied central nervous system pathology.
PubMed: 38934385
DOI: 10.4103/NRR.NRR-D-24-00055 -
Neural Regeneration Research Jun 2024Successful polyethylene glycol fusion (PEG-fusion) of severed axons following peripheral nerve injuries for PEG-fused axons has been reported to: (1) rapidly restore...
Successful polyethylene glycol fusion (PEG-fusion) of severed axons following peripheral nerve injuries for PEG-fused axons has been reported to: (1) rapidly restore electrophysiological continuity; (2) prevent distal Wallerian Degeneration and maintain their myelin sheaths; (3) promote primarily motor, voluntary behavioral recoveries as assessed by the Sciatic Functional Index; and, (4) rapidly produce correct and incorrect connections in many possible combinations that produce rapid and extensive recovery of functional peripheral nervous system/central nervous system connections and reflex (e.g., toe twitch) or voluntary behaviors. The preceding companion paper describes sensory terminal field reorganization following PEG-fusion repair of sciatic nerve transections or ablations; however, sensory behavioral recovery has not been explicitly explored following PEG-fusion repair. In the current study, we confirmed the success of PEG-fusion surgeries according to criteria (1-3) above and more extensively investigated whether PEG-fusion enhanced mechanical nociceptive recovery following sciatic transection in male and female outbred Sprague-Dawley and inbred Lewis rats. Mechanical nociceptive responses were assessed by measuring withdrawal thresholds using von Frey filaments on the dorsal and midplantar regions of the hindpaws. Dorsal von Frey filament test was a more reliable method than plantar von Frey filament test to assess mechanical nociceptive sensitivity following sciatic nerve transections. Baseline withdrawal thresholds of the sciatic-mediated lateral dorsal region differed significantly across strain but not sex. Withdrawal thresholds did not change significantly from baseline in chronic Unoperated and Sham-operated rats. Following sciatic transection, all rats exhibited severe hyposensitivity to stimuli at the lateral dorsal region of the hindpaw ipsilateral to the injury. However, PEG-fused rats exhibited significantly earlier return to baseline withdrawal thresholds than Negative Control rats. Furthermore, PEG-fused rats with significantly improved Sciatic Functional Index scores at or after 4 weeks postoperatively exhibited yet-earlier von Frey filament recovery compared with those without Sciatic Functional Index recovery, suggesting a correlation between successful pPEG-fusion and both motor-dominant and sensory-dominant behavioral recoveries. This correlation was independent of the sex or strain of the rat. Furthermore, our data showed that the acceleration of von Frey filament sensory recovery to baseline was solely due to the PEG-fused sciatic nerve and not saphenous nerve collateral outgrowths. No chronic hypersensitivity developed in any rat up to 12 weeks. All these data suggest that PEG-fusion repair of transection peripheral nerve injuries could have important clinical benefits.
PubMed: 38934383
DOI: 10.4103/NRR.NRR-D-23-01846 -
Journal of Child Psychology and... Jun 2024Previous research has linked prenatal maternal infections to later childhood developmental outcomes and socioemotional difficulties. However, existing studies have...
BACKGROUND
Previous research has linked prenatal maternal infections to later childhood developmental outcomes and socioemotional difficulties. However, existing studies have relied on retrospectively self-reported survey data, or data on hospital-recorded infections only, resulting in gaps in data collection.
METHODS
This study used a large linked administrative health dataset, bringing together data from birth records, hospital records, prescriptions and routine child health reviews for 55,856 children born in Greater Glasgow & Clyde, Scotland, 2011-2015, and their mothers. Logistic regression models examined associations between prenatal infections, measured as both hospital-diagnosed prenatal infections and receipt of infection-related prescription(s) during pregnancy, and childhood developmental concern(s) identified by health visitors during 6-8 week or 27-30 month health reviews. Secondary analyses examined whether results varied by (a) specific developmental outcome types (gross-motor-skills, hearing-communication, vision-social-awareness, personal-social, emotional-behavioural-attention and speech-language-communication) and (b) the trimester(s) in which infections occurred.
RESULTS
After confounder/covariate adjustment, hospital-diagnosed infections were associated with increased odds of having at least one developmental concern (OR: 1.30; 95% CI: 1.19-1.42). This was broadly consistent across all developmental outcome types and appeared to be specifically linked to infections occurring in pregnancy trimesters 2 (OR: 1.34; 95% CI: 1.07-1.67) and 3 (OR: 1.33; 95% CI: 1.21-1.47), that is the trimesters in which foetal brain myelination occurs. Infection-related prescriptions were not associated with any clear increase in odds of having at least one developmental concern after confounder/covariate adjustment (OR: 1.03; 95% CI: 0.98-1.08), but were associated with slightly increased odds of concerns specifically related to personal-social (OR: 1.12; 95% CI: 1.03-1.22) and emotional-behavioural-attention (OR: 1.15; 95% CI: 1.08-1.22) development.
CONCLUSIONS
Prenatal infections, particularly those which are hospital-diagnosed (and likely more severe), are associated with early childhood developmental outcomes. Prevention of prenatal infections, and monitoring of support needs of affected children, may improve childhood development, but causality remains to be established.
PubMed: 38934255
DOI: 10.1111/jcpp.14028 -
Brain Multiphysics Jun 2024Knowledge of the mechanical properties of brain tissue is essential to understanding the mechanisms underlying traumatic brain injury (TBI) and to creating accurate...
UNLABELLED
Knowledge of the mechanical properties of brain tissue is essential to understanding the mechanisms underlying traumatic brain injury (TBI) and to creating accurate computational models of TBI and neurosurgical simulation. Brain white matter, which is composed of aligned, myelinated, axonal fibers, is structurally anisotropic. White matter also exhibits mechanical anisotropy, as measured by magnetic resonance elastography (MRE), but measurements of anisotropy obtained by mechanical testing of white matter have been inconsistent. The minipig has a gyrencephalic brain with similar white matter and gray matter proportions to humans and therefore provides a relevant model for human brain mechanics. In this study, we compare estimates of anisotropic mechanical properties of the minipig brain obtained by identical, non-invasive methods in the live ( and dead animals . To do so, we combine wave displacement fields from MRE and fiber directions derived from diffusion tensor imaging (DTI) with a finite element-based, transversely-isotropic nonlinear inversion (TI-NLI) algorithm. Maps of anisotropic mechanical properties in the minipig brain were generated for each animal alive and at specific times post-mortem. These maps show that white matter is stiffer, more dissipative, and more anisotropic than gray matter when the minipig is alive, but that these differences largely disappear post-mortem, with the exception of tensile anisotropy. Overall, brain tissue becomes stiffer, less dissipative, and less mechanically anisotropic post-mortem. These findings emphasize the importance of testing brain tissue properties .
STATEMENT OF SIGNIFICANCE
In this study, MRE and DTI in the minipig were combined to estimate, for the first time, anisotropic mechanical properties in the living brain and in the same brain after death. Significant differences were observed in the anisotropic behavior of brain tissue post-mortem. These results demonstrate the importance of measuring brain tissue properties as well as and provide new quantitative data for the development of computational models of brain biomechanics.
PubMed: 38933498
DOI: 10.1016/j.brain.2024.100091 -
Micromachines Jun 2024Inherited primary open-angle glaucoma (POAG) in Beagle dogs is a well-established large animal model of glaucoma and is caused by a G661R missense mutation in the gene....
BACKGROUND
Inherited primary open-angle glaucoma (POAG) in Beagle dogs is a well-established large animal model of glaucoma and is caused by a G661R missense mutation in the gene. Using this model, the study describes early clinical disease markers for canine glaucoma.
METHODS
Spectral-domain optical coherence tomography (SD-OCT) was used to assess nine adult, -mutant (median age 45.6 months, range 28.8-52.8 months; mean diurnal intraocular pressure (IOP): 29.9 +/- SEM 0.44 mmHg) and three related age-matched control Beagles (mean diurnal IOP: 18.0 +/- SEM 0.53 mmHg).
RESULTS
Of all the optic nerve head (ONH) parameters evaluated, the loss of myelin peak height in the horizontal plane was most significant (from 154 +/- SEM 38.4 μm to 9.3 +/- SEM 22.1 μm; < 0.01). There was a strong significant negative correlation between myelin peak height and IOP (Spearman correlation: -0.78; < 0.003). There were no significant differences in the thickness of any retinal layers evaluated.
CONCLUSIONS
SD-OCT is a useful tool to detect early glaucomatous damage to the ONH in dogs before vision loss. Loss in myelin peak height without inner retinal thinning was identified as an early clinical disease marker. This suggests that initial degenerative changes are mostly due to the loss of myelin.
PubMed: 38930749
DOI: 10.3390/mi15060780 -
Journal of Clinical Medicine Jun 2024: Myelin oligodendrocyte glycoprotein (MOG) is exclusively expressed in the central nervous system (CNS) and is found on the outer surface of oligodendrocytes.... (Review)
Review
: Myelin oligodendrocyte glycoprotein (MOG) is exclusively expressed in the central nervous system (CNS) and is found on the outer surface of oligodendrocytes. Antibodies to MOG are associated with CNS demyelination, whereas peripheral nervous system (PNS) demyelination is seldom reported to be related to MOG-IgG. : The database of patients seen in our neurological academic center was searched for MOG-IgG seropositivity and concomitant demyelinating polyneuropathy. For the purpose of the review, in March 2024, we searched for case reports and case series in the following databases: PubMed, Scopus, Cochrane, and ScienceDirect. Inclusion criteria were MOG-IgG seropositivity and demyelinating polyneuropathy. Exclusion criteria were type of publication other than case reports and case series, unconfirmed diagnosis of demyelinating polyneuropathy, and other diseases causing demyelination in either the CNS or PNS. Critical appraisal of the selected case reports and case series was realized by JBI. : Four new cases were identified with MOG-IgG and confirmed demyelinating polyneuropathy. This review identified 22 cases that have been published since 2018. Clinical, imaging, neurophysiological, and immunological characteristics, as well as treatment options and outcomes are presented and compared to those of other cases with combined central and peripheral demyelination (CCPD). : The pathogenetic mechanism is unclear; thus, different hypotheses are discussed. New case reporting and large cohort studies will help further the exploration of the underlying mechanism and guide more effective therapeutic interventions.
PubMed: 38930142
DOI: 10.3390/jcm13123604 -
Journal of Personalized Medicine Jun 2024Primary demyelinating disorders of the central nervous system (CNS) include multiple sclerosis and the orphan conditions neuromyelitis optica spectrum disorder (NMOSD)...
Development Perspectives for Curative Technologies in Primary Demyelinating Disorders of the Central Nervous System with Neuromyelitis Optica Spectrum Disorder (NMOSD) and Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease (MOGAD) at the Forefront.
Primary demyelinating disorders of the central nervous system (CNS) include multiple sclerosis and the orphan conditions neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein IgG-associated disease (MOGAD). Curative technologies under development aim to selectively block autoimmune reactions against specific autoantigens while preserving the responsiveness of the immune system to other antigens. Our analysis focused on target patient selection for such developments, carefully considering the relevant clinical, regulatory, and market-related aspects. We found that the selection of patients with orphan conditions as target populations offers several advantages. Treatments for orphan conditions are associated with limited production capacity, qualify for regulatory incentives, and may require significantly shorter and lower-scale clinical programs. Furthermore, they may meet a higher acceptable cost-effectiveness threshold in order to compensate for the low numbers of patients to be treated. Finally, curative technologies targeting orphan indications could enter less competitive markets with lower risk of generic price erosion and would benefit from additional market protection measures available only for orphan products. These advantages position orphan conditions and subgroups as the most attractive target indications among primary demyelinating disorders of the CNS. The authors believe that after successful proof-of-principle demonstrations in orphan conditions, broader autoimmune patient populations may also benefit from the success of these pioneering developments.
PubMed: 38929820
DOI: 10.3390/jpm14060599