Neuropathology and Applied Neurobiology最新文献

Growth arrest-specific 6 (GAS6) protein is required for cell survival through its role in TAM receptor signalling. Here, we investigate a novel autosomal recessive demyelinating disorder in a 9-year-old male presenting with progressive motor dysfunction, spasticity, seizures and cognitive decline. MRI revealed multifocal T2/FLAIR hyperintensities in periventricular, juxtacortical and brainstem white matter regions. Exome sequencing uncovered a homozygous stop-gain variant in GAS6 (c.444G>A; p.Trp148Ter). The variant results in nonsense-mediated decay and loss of protein expression and secretion. Functional assays in patient fibroblasts and HOG oligodendrocytes showed downregulation of neurotrophic and myelin-related genes (NTRK2, CNTF, EGR1, MBP, PLP), defective oligodendrocyte-process formation and increased G₀/G₁ cell cycle arrest. Rescue experiments confirmed that wild-type GAS6, but not the truncated variant, restored cellular function. These findings establish GAS6 as a critical regulator of neuro-glial homeostasis and identify its deficiency as the cause of a previously unreported childhood-onset demyelinating disease.

We describe the case of a 29-year-old woman with focal drug-resistant epilepsy and an unusual Focal Cortical Dysplasia (FCD) IIa with lipofuscin accumulation in dysmorphic neurons. We discuss the commonalities and discrepancies between the present case and FCDIIa cases without lipofuscin accumulation at the clinical, histopathological and proteomic levels. (a) Coronal 3D-FLAIR imaging demonstrates an unusually deep F1-F2 sulcus associated with subtle signal alteration (arrowhead). (b) Coronal FDG-PET coregistered with T1 3D MRI reveals marked hypometabolism of the same sulcus (arrowhead). (c-f) Histological images of the surgical specimen show numerous dysmorphic neurons (DN), a typical hallmark of FCD type IIa. Notably, DN (green arrows) exhibit cytoplasmic PAS-positive granular material identified as lipofuscin (c), neurofilament accumulation with peculiar 'ring-like' aspect (d,e) and occasional ubiquitin-binding protein p62 labelling (f). (g-h) Matrix-assisted laser desorption/ionisation imaging mass spectrometry (MALDI-IMS) further supports differences at proteomic level between the present case and classic FCDIIa without lipofuscin accumulation.

Background: Focal cortical dysplasia IIb (FCDIIb) and tuberous sclerosis complex (TSC) show persistent neuroinflammation that promotes epileptogenesis and epilepsy progression, suggesting that endogenous resolution of inflammation is inadequate to relieve neuronal network hyperexcitability. G-protein-coupled receptor 32 (GPR32) is a key regulator of inflammation resolution and we aimed to explore the roles of GPR32 in cortical lesions of patients with FCDIIb and TSC.

Method: We examined the expression and distribution of GPR32 in patients with FCDIIb and TSC and its effects on human microglial cell activation, inflammation and the electrophysiological properties of neurons.

Results: GPR32 and Resolvin D1 expression was significantly lower in cortical lesions of patients with FCDIIb and TSC than in controls and were negatively correlated with seizure frequency. GPR32 was widely distributed in neurons and microglia and was nearly absent in astrocytes. Furthermore, the Src homology region 2-containing protein tyrosine phosphatase 2 (SHP2) pathway was downregulated in patients with FCDIIb and TSC. The GPR32/SHP2/nuclear factor-kappa B pathway inhibited the M1 transformation of microglia to produce numerous pro-inflammatory mediators and promoted M2 polarisation. GPR32 also regulated neuronal excitability by reducing the amplitude and frequency of spontaneous excitatory postsynaptic currents.

Conclusion: Our results suggest that GPR32 may help control epilepsy in patients with FCDIIb and TSC.

Aims: Dysferlin, a 237-kDa protein crucial for muscle function, is deficient in dysferlinopathy, a rare form of muscular dystrophy caused by recessive mutations in the DYSF gene. While genetic analysis is the primary diagnostic approach, protein-based studies remain essential for confirming pathogenicity, particularly for variants of uncertain significance. This study aims to validate an immunohistochemical assay for dysferlin detection in neutrophils from peripheral blood films (PBF) and to evaluate how different storage conditions affect its performance, with particular focus on refining variables that may affect assay reliability and reproducibility.

Methods: We performed a follow-up assessment of a new immunoassay to detect dysferlin expression in neutrophils from PBFs, using samples from genetically confirmed dysferlinopathy patients and healthy controls in an Indian cohort.

Results: The assay exhibited very high sensitivity, but its specificity was affected by sample quality and storage conditions. Protein degradation occurred in samples stored at room temperature in environments exceeding 30°C, while storage at 4°C preserved dysferlin immunoreactivity for up to 20 weeks.

Conclusions: The PBF-based dysferlin assay is a rapid, cost-effective and minimally invasive screening tool, well-suited for use in resource-limited settings. It provides a viable approach for initial screening and variant assessment. As the assay's reliability is influenced by sample quality and storage conditions, proper training in collection techniques and strict adherence to storage protocols are essential for ensuring diagnostic accuracy and enabling broader clinical application.

Background: Alcohol use disorder (AUD) is a chronically relapsing condition marked by a pathological shift in behaviour, where excessive motivational drive predominates over cognitive control. Brodmann area 6 (BA6) is a key cortical region that integrates cognitive control with motor output and striatal circuits. Cellular alterations in the BA6 can shift from flexible, goal-directed planning to habitual, compulsive behaviours.

Method: Here, we examined cellular changes in the human post-mortem cortex from AUD cases (n = 9) and age-matched controls (n = 10). The density of parvalbumin (PV) neurons and perineuronal nets (PNN) was analysed from immunofluorescent-stained sections. The number of PV neurons, PNN-positive cells, and PV neurons colocalised with PNN across cortical layers II-VI in BA6 regions was quantified.

Results: Across layers II/VI, the density of PV neurons and PNN was similar in the control and AUD groups, indicative of no cellular loss in the BA6. Analysis of the colocalisation of PV neurons with PNN revealed no effect in layers II/III (p = 0.720). However, there was a significant increase in colocalisation of PV neurons with PNN in layers IV (p = 0.043) and V/VI (p = 0.025) in the AUD compared to the control group.

Conclusion: This study reveals layer-specific remodelling of PNN and PV networks in the human cortex in AUD cases, suggesting shifts in AUD behaviours are potentially attributed to PV neuronal activity regulated by PNN in specific cortical layers. Together, this study identifies AUD-related neuropathology and provides insight into the mechanisms underlying persistent alcohol-seeking behaviour.

Aims: X-linked McLeod neuroacanthocytosis syndrome (MLS) is a rare neurodegenerative disorder characterised by the presence of red blood cell acanthocytosis and a chorea syndrome. Analogous to Huntington's disease (HD), MLS displays cognitive and behavioural symptoms besides the progressive movement disorder. This study aimed to describe the neuropathology of MLS in the largest case series to date.

Methods: Clinical data were collected, and neuropathological assessments were performed on eight male MLS patients originating from Finland, New Zealand, Switzerland, Scotland and the United States.

Results: Macroscopic data were available from six patients, with five showing atrophy of the basal ganglia, which was more pronounced in the caudate nucleus and to a lesser extent in the putamen and pallidum. Histology revealed neuronal loss and accompanying gliosis in the basal ganglia of all patients. The extent of these alterations varied widely, with a decreasing gradient of severity from the caudate nucleus to the putamen and the pallidum, mirroring the macroscopic findings. In addition, we detected intraneuronal vacuoles in the striatum in half of the patients.

Conclusions: MLS neuropathology is characterised macroscopically by atrophy and microscopically by neuronal loss and gliosis of the basal ganglia, with a decreasing gradient of severity from the caudate nucleus, the putamen to the pallidum. Analogous to the grading system for HD, we propose a neuropathological grading system for MLS based on the current observations in the largest MLS cohort examined to date. Standardised criteria are crucial for neuropathological assessment of this extremely rare disease.

Early-onset Parkinsonism is a neurodegenerative disorder that can arise from rare genetic variants. We report a 21-year-old female proband with progressive bradykinesia, symmetrical rigidity, resting tremors, postural instability, executive dysfunction, and behavioural disturbances. Brain MRI revealed asymmetric thinning of the substantia nigra pars compacta, consistent with dopaminergic neuronal loss in early-onset Parkinsonism. Exome sequencing identified a novel homozygous missense variant in OTUD3 (c.559C>T; p.Arg187Trp), ultra-rarely present as a heterozygous allele in gnomAD and absent in ClinVar, and inherited in an autosomal recessive manner. The substituted arginine at position 187 lies within a β-sheet of the highly conserved OTU deubiquitinase domain. In silico predictions classified the variant as deleterious, disease-causing, and structurally destabilising. Molecular dynamics simulations additionally predicted R187W-induced destabilisation, including increased backbone flexibility, loss of hydrogen bonding, solvent exposure of the hydrophobic tryptophan residue, and partial collapse of the catalytic domain. In proband-derived fibroblasts, OTUD3-R187W exhibited cytosolic aggregation and failed to regulate its substrate IRP2, resulting in IRP2 accumulation and intracellular iron overload. These cells also showed increased cell death. OTUD3 protein interaction networks and gene ontology analyses revealed involvement in ubiquitin signalling, cytoskeletal organisation, and transcriptional regulation. Together, these data demonstrate that the OTUD3-R187W variant compromises structural integrity and cellular function, contributing to early-onset Parkinsonism. This study implicates OTUD3 as a novel gene linked to neurodegeneration and highlights its role in maintaining midbrain neuronal integrity.