-
Research Square May 2024White matter loss is a well-documented phenomenon in Alzheimer's disease (AD) patients that has been recognized for decades. However, the underlying reasons for the...
BACKGROUND
White matter loss is a well-documented phenomenon in Alzheimer's disease (AD) patients that has been recognized for decades. However, the underlying reasons for the failure of oligodendrocyte progenitor cells (OPCs) to repair myelin deficits in these patients remain elusive. A single nucleotide polymorphism (SNP) in Clusterin has been identified as a risk factor for late-onset Alzheimer's disease and linked to a decrease in white matter integrity in healthy adults, but its specific role in oligodendrocyte function and myelin maintenance in Alzheimer's disease pathology remains unclear.
METHODS
To investigate the impact of Clusterin on OPCs in the context of Alzheimer's disease, we employed a combination of immunofluorescence and transmission electron microscopy techniques, primary culture of OPCs, and an animal model of Alzheimer's disease.
RESULTS
Our findings demonstrate that Clusterin, a risk factor for late-onset AD, is produced by OPCs and inhibits their differentiation into oligodendrocytes. Specifically, we observed upregulation of Clusterin in OPCs in the 5xFAD mouse model of AD. We also found that the phagocytosis of debris, including amyloid beta (Aβ), myelin, and apoptotic cells leads to the upregulation of Clusterin in OPCs. In vivo experiments confirmed that Aβ oligomers stimulate Clusterin upregulation and that OPCs are capable of phagocytosing Aβ. Furthermore, we discovered that Clusterin significantly inhibits OPC differentiation and hinders the production of myelin proteins. Finally, we demonstrate that Clusterin inhibits OPC differentiation by reducing the production of IL-9 by OPCs.
CONCLUSION
Our data suggest that Clusterin may play a key role in the impaired myelin repair observed in AD and could serve as a promising therapeutic target for addressing AD-associated cognitive decline.
PubMed: 38853911
DOI: 10.21203/rs.3.rs-4415143/v1 -
NeuroImage Aug 2024To separate the contributions of paramagnetic and diamagnetic sources within a voxel, a magnetic susceptibility source separation method based solely on gradient-echo...
To separate the contributions of paramagnetic and diamagnetic sources within a voxel, a magnetic susceptibility source separation method based solely on gradient-echo data has been developed. To measure the opposing susceptibility sources more accurately, we propose a novel single-orientation quantitative susceptibility mapping method with adaptive relaxometric constant estimation (QSM-ARCS) for susceptibility source separation. Moreover, opposing susceptibilities and their anisotropic effects were determined in healthy volunteers in the white matter. Multiple spoiled gradient echo and diffusion tensor imaging of ten healthy volunteers was obtained using a 3 T magnetic resonance scanner. After the opposing susceptibility and fractional anisotropy (FA) maps had been reconstructed, the parametric maps were spatially normalized. To evaluate the agreements of QSM-ARCS against the susceptibility source separation method using R2 and R2* maps (χ-separation) by Bland-Altman plots, the opposing susceptibility values were measured using white and deep gray matter atlases. We then evaluated the relationships between the opposing susceptibilities and FAs in the white matter and used a field-to-fiber angle to assess the fiber orientation dependencies of the opposing susceptibilities. The susceptibility maps in QSM-ARCS were successfully reconstructed without large artifacts. In the Bland-Altman analyses, the opposing QSM-ARCS susceptibility values excellently agreed with the χ-separation maps. Significant inverse and proportional correlations were observed between FA and the negative and positive susceptibilities estimated by QSM-ARCS. The fiber orientation dependencies of the negative susceptibility represented a nonmonotonic feature. Conversely, the positive susceptibility increased linearly with the fiber angle with respect to the B0 field. The QSM-ARCS could accurately estimate the opposing susceptibilities, which were identical values of χ-separation, even using gradient echo alone. The opposing susceptibilities might offer direct biomarkers for assessment of the myelin and iron content in glial cells and, through the underlying magnetic sources, provide biologic insights toward clinical transition.
Topics: Humans; Male; Adult; Female; White Matter; Diffusion Tensor Imaging; Brain; Young Adult; Brain Mapping; Image Processing, Computer-Assisted; Magnetic Resonance Imaging
PubMed: 38852804
DOI: 10.1016/j.neuroimage.2024.120676 -
Stem Cell Research Aug 2024Hypomyelinating leukodystrophies (HLD) are a group of heterogeneous genetic disorders characterized by a deficit in myelin deposition during brain development....
Production of an induced pluripotent stem cell line CSSi018-A (14192) from a patient with hypomyelinating leukodystrophy 7 (HLD7) carrying biallelic variants of POLR3A (c.1802 T > A; c.4072G > A).
Hypomyelinating leukodystrophies (HLD) are a group of heterogeneous genetic disorders characterized by a deficit in myelin deposition during brain development. Specifically, 4H-Leukodystrophy is a recessive disease due to biallelic mutations in the POLR3A gene, which encodes one of the subunits forming the catalytic core of RNA polymerase III (PolIII). The disease also presents non-neurological signs such as hypodontia and hypogonadotropic hypogonadism. Here, we report the generation of a human induced pluripotent stem cell (hiPSC) line from fibroblasts of the first identified carrier of the biallelic POLR3A variants c.1802 T > A and c.4072G > A.
Topics: Humans; Induced Pluripotent Stem Cells; RNA Polymerase III; Cell Line; Hereditary Central Nervous System Demyelinating Diseases; Male; Alleles
PubMed: 38852424
DOI: 10.1016/j.scr.2024.103468 -
Journal of Neuroinflammation Jun 2024Extracellular vesicles (EVs) are released by all cells, can cross the blood-brain barrier, and have been shown to play an important role in cellular communication,...
Extracellular vesicles (EVs) are released by all cells, can cross the blood-brain barrier, and have been shown to play an important role in cellular communication, substance shuttling, and immune modulation. In recent years EVs have shifted into focus in multiple sclerosis (MS) research as potential plasma biomarkers and therapeutic vehicles. Yet little is known about the disease-associated changes in EVs in the central nervous system (CNS). To address this gap, we characterized the physical and proteomic changes of mouse spinal cord-derived EVs before and at 16 and 25 days after the induction of experimental autoimmune encephalomyelitis (EAE), a neuroinflammatory model of MS. Using various bioinformatic tools, we found changes in inflammatory, glial, and synaptic proteins and pathways, as well as a shift in the predicted contribution of immune and glial cell types over time. These results show that EVs provide snapshots of crucial disease processes such as CNS-compartmentalized inflammation, re/de-myelination, and synaptic pathology, and might also mediate these processes. Additionally, inflammatory plasma EV biomarkers previously identified in people with MS were also altered in EAE spinal cord EVs, suggesting commonalities of EV-related pathological processes during EAE and MS and overlap of EV proteomic changes between CNS and circulating EVs.
Topics: Extracellular Vesicles; Animals; Spinal Cord; Mice; Encephalomyelitis, Autoimmune, Experimental; Mice, Inbred C57BL; Female; Neuroinflammatory Diseases; Proteomics
PubMed: 38851724
DOI: 10.1186/s12974-024-03147-y -
Brain and Behavior Jun 2024In vivo myeloarchitectonic mapping based on Magnetic Resonance Imaging (MRI) provides a unique view of gray matter myelin content and offers information complementary to...
INTRODUCTION
In vivo myeloarchitectonic mapping based on Magnetic Resonance Imaging (MRI) provides a unique view of gray matter myelin content and offers information complementary to other morphological indices commonly employed in studies of autism spectrum disorder (ASD). The current study sought to determine if intracortical myelin content (MC) and its age-related trajectories differ between middle aged to older adults with ASD and age-matched typical comparison participants.
METHODS
Data from 30 individuals with ASD and 36 age-matched typical comparison participants aged 40-70 years were analyzed. Given substantial heterogeneity in both etiology and outcomes in ASD, we utilized both group-level and subject-level analysis approaches to test for signs of atypical intracortical MC as estimated by T1w/T2w ratio.
RESULTS
Group-level analyses showed no significant differences in average T1w/T2w ratio or its associations with age between groups, but revealed significant positive main effects of age bilaterally, with T1w/T2w ratio increasing with age across much of the cortex. In subject-level analyses, participants were classified into subgroups based on presence or absence of clusters of aberrant T1w/T2w ratio, and lower neuropsychological function was observed in the ASD subgroup with atypically high T1w/T2w ratio in spatially heterogeneous cortical regions. These differences were observed across several neuropsychological domains, including overall intellectual functioning, processing speed, and aspects of executive function.
CONCLUSIONS
The group-level and subject-level approaches employed here demonstrate the value of examining inter-individual variability and provide important preliminary insights into relationships between brain structure and cognition in the second half of the lifespan in ASD, suggesting shared factors contributing to atypical intracortical myelin content and poorer cognitive outcomes for a subset of middle aged to older autistic adults. These atypicalities likely reflect diverse histories of neurodevelopmental deficits, and possible compensatory changes, compounded by processes of aging, and may serve as useful markers of vulnerability to further cognitive decline in older adults with ASD.
Topics: Humans; Male; Female; Magnetic Resonance Imaging; Aged; Middle Aged; Myelin Sheath; Autism Spectrum Disorder; Adult; Cerebral Cortex; Neuropsychological Tests; Aging
PubMed: 38849980
DOI: 10.1002/brb3.3594 -
Scientific Reports Jun 2024Multiple sclerosis (MS) is an autoimmune demyelinating disease affecting the central nervous system (CNS). T helper (Th) 17 cells are involved in the pathogenesis of MS...
Myelin oligodendrocyte glycoprotein reactive Th17 cells drive Janus Kinase 1 dependent transcriptional reprogramming in astrocytes and alter cell surface cytokine receptor profiles during experimental autoimmune encephalomyelitis.
Multiple sclerosis (MS) is an autoimmune demyelinating disease affecting the central nervous system (CNS). T helper (Th) 17 cells are involved in the pathogenesis of MS and its animal model of experimental autoimmune encephalomyelitis (EAE) by infiltrating the CNS and producing effector molecules that engage resident glial cells. Among these glial cells, astrocytes have a central role in coordinating inflammatory processes by responding to cytokines and chemokines released by Th17 cells. In this study, we examined the impact of pathogenic Th17 cells on astrocytes in vitro and in vivo. We identified that Th17 cells reprogram astrocytes by driving transcriptomic changes partly through a Janus Kinase (JAK)1-dependent mechanism, which included increased chemokines, interferon-inducible genes, and cytokine receptors. In vivo, we observed a region-specific heterogeneity in the expression of cell surface cytokine receptors on astrocytes, including those for IFN-γ, IL-1, TNF-α, IL-17, TGFβ, and IL-10. Additionally, these receptors were dynamically regulated during EAE induced by adoptive transfer of myelin-reactive Th17 cells. This study overall provides evidence of Th17 cell reprogramming of astrocytes, which may drive changes in the astrocytic responsiveness to cytokines during autoimmune neuroinflammation.
Topics: Encephalomyelitis, Autoimmune, Experimental; Animals; Astrocytes; Th17 Cells; Mice; Myelin-Oligodendrocyte Glycoprotein; Receptors, Cytokine; Janus Kinase 1; Mice, Inbred C57BL; Cytokines; Cellular Reprogramming; Female; Cells, Cultured
PubMed: 38849434
DOI: 10.1038/s41598-024-63877-0 -
Cureus May 2024Neuromyelitis optica spectrum disorder (NMOSD) is a rare, acquired demyelinating condition predominantly affecting middle-aged women and is characterized by spinal cord...
Neuromyelitis optica spectrum disorder (NMOSD) is a rare, acquired demyelinating condition predominantly affecting middle-aged women and is characterized by spinal cord inflammation and optic neuritis. Anti-aquaporin 4 (AQP4) antibodies are typically seen in NMOSD. However, myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) shares clinical and imaging similarities. In NMOSD, longitudinally extensive spinal cord lesions (LESCLs), optic neuritis predominantly affecting the posterior aspect of optic nerves, and optic radiations are seen on magnetic resonance imaging (MRI). The brain parenchymal lesions particularly involve the dorsal medulla (area postrema). The report presents a case of a 26-year-old female with recurrent episodes of weakness, pain, and sensory symptoms in both upper and lower limbs who was initially treated for multiple sclerosis. Upon experiencing new symptoms of blurred vision and ataxia, an MRI of the spine and brain was performed, which showed short-segment cervical cord involvement and a lesion in the conus medullaris, raising the suspicion of NMOSD. Subsequent antibody testing confirmed the presence of anti-AQP4 antibodies. While the involvement of the conus medullaris is classically associated with MOGAD, unusual findings in the present case highlight the importance of comprehensive imaging evaluation and raising awareness among clinicians and radiologists regarding the imaging spectrum of NMOSD, thus facilitating timely diagnosis and tailored treatment strategies.
PubMed: 38846197
DOI: 10.7759/cureus.59765 -
Cureus May 2024Optic nerve schwannoma is a very rarely occurring tumor described in the literature. It is due to the fact that the optic nerve is myelinated by oligodendrocytes....
Optic nerve schwannoma is a very rarely occurring tumor described in the literature. It is due to the fact that the optic nerve is myelinated by oligodendrocytes. Schwannomas are tumors of the peripheral nervous system, hence optic nerve schwannoma is a rare phenomenon. A 34-year-old patient presented in the outpatient department with complaints of gradual painless protrusion of the left eye (LE) for the past one year. There was no history of diminution of vision. On examination, vision in both eyes was 6/6, anterior segment examination in both eyes was normal, and pupils were central, circular, and reacting to light. Intraocular pressure was measured on a noncontact tonometer and was within normal range. Both eyes' optic disc, fundus, and visual fields were normal. On inspection, axial proptosis was noted in the LE. Proptosis measurement (on Hertel exophthalmometer) in the right eye was 17 mm and in the left eye was 21 mm. MRI of the orbit without contrast was done and showed a well-defined, soft tissue lesion of the optic nerve in the intraconal compartment of the left orbit. Surgical excision of the tumor was done by lateral orbitotomy approach and the tumor was removed in total. Histopathological examination of the mass revealed a benign spindle cell neoplasm suggestive of schwannoma. Postoperatively, proptosis was resolved, 17 mm both in the right and left eye (on Hertel exophthalmometer), and vision in LE remained unchanged (6/6). Postoperatively, intraocular pressure (on noncontact tonometer) was within normal range, and the optic disc, fundus, and visual fields were normal.
PubMed: 38846181
DOI: 10.7759/cureus.59824 -
Juntendo Iji Zasshi = Juntendo Medical... 2023Axonal outgrowth after stroke plays an important role in tissue repair and is critical for functional recovery. In the peri-infarct area of a rat middle cerebral artery... (Review)
Review
Axonal outgrowth after stroke plays an important role in tissue repair and is critical for functional recovery. In the peri-infarct area of a rat middle cerebral artery occlusion model, we found that the axons and dendrites that had fallen off in the acute phase of stroke (7 days) were regenerated in the chronic phase of stroke (56 days). , we showed that phosphatase tensin homolog deleted on chromosome 10/Akt/Glycogen synthase kinase 3β signaling is implicated in postischemic axonal regeneration. In a rat model of chronic cerebral hypoperfusion, oral administration of L-carnitine induced axonal and oligodendrocyte regeneration in the cerebral white matter, resulting in myelin thickening, and it improved cognitive impairment in rats with chronic cerebral ischemia. Recently, it has been shown that exosomes enhanced functional recovery after stroke. Exosome treatment has less tumorigenicity, does not occlude the microvascular system, has low immunogenicity, and does not require a host immune response compared to conventional cell therapy. Several studies demonstrated specific microRNA in exosomes, which regulated signaling pathways related to neurogenesis after stroke. Collectively, there are various mechanisms of axonal regeneration and functional recovery after stroke, and it is expected that new therapeutic agents for stroke with the aim of axonal regeneration will be developed and used in real-world clinical practice in the future.
PubMed: 38845728
DOI: 10.14789/jmj.JMJ23-0025-R -
Gut Microbes 2024Gut microbiota is responsible for essential functions in human health. Several communication axes between gut microbiota and other organs via neural, endocrine, and...
Gut microbiota is responsible for essential functions in human health. Several communication axes between gut microbiota and other organs via neural, endocrine, and immune pathways have been described, and perturbation of gut microbiota composition has been implicated in the onset and progression of an emerging number of diseases. Here, we analyzed peripheral nerves, dorsal root ganglia (DRG), and skeletal muscles of neonatal and young adult mice with the following gut microbiota status: a) germ-free (GF), b) gnotobiotic, selectively colonized with 12 specific gut bacterial strains (Oligo-Mouse-Microbiota, OMM12), or c) natural complex gut microbiota (CGM). Stereological and morphometric analyses revealed that the absence of gut microbiota impairs the development of somatic median nerves, resulting in smaller diameter and hypermyelinated axons, as well as in smaller unmyelinated fibers. Accordingly, DRG and sciatic nerve transcriptomic analyses highlighted a panel of differentially expressed developmental and myelination genes. Interestingly, the type III isoform of Neuregulin1 (NRG1), known to be a neuronal signal essential for Schwann cell myelination, was overexpressed in young adult GF mice, with consequent overexpression of the transcription factor Early Growth Response 2 (), a fundamental gene expressed by Schwann cells at the onset of myelination. Finally, GF status resulted in histologically atrophic skeletal muscles, impaired formation of neuromuscular junctions, and deregulated expression of related genes. In conclusion, we demonstrate for the first time a gut microbiota regulatory impact on proper development of the somatic peripheral nervous system and its functional connection to skeletal muscles, thus suggesting the existence of a novel 'Gut Microbiota-Peripheral Nervous System-axis.'
Topics: Animals; Gastrointestinal Microbiome; Neuromuscular Junction; Mice; Ganglia, Spinal; Germ-Free Life; Peripheral Nerves; Muscle, Skeletal; Mice, Inbred C57BL; Neuregulin-1; Male; Bacteria; Schwann Cells
PubMed: 38845453
DOI: 10.1080/19490976.2024.2363015