Brain Pathology最新文献

The Consortium to Inform Molecular and Practical Approaches to Central Nervous System Tumor Taxonomy (cIMPACT-NOW) updates provide guidelines for the diagnosis of central nervous system (CNS) tumors and suggestions for future World Health Organization (WHO) classification. Following publication of the fifth edition WHO Classification of CNS Tumors (WHO CNS5) in 2021, the cIMPACT-NOW working group “Clarification” reviewed WHO CNS5 and prioritized two topics for further elucidation: (a) distinction of Glioblastoma, IDH-wildtype from Diffuse pediatric-type high-grade glioma, H3-wildtype, and IDH-wildtype and (b) clarification of subgroups of posterior fossa (PF) ependymal tumors. Recommendations regarding the IDH- and H3-wildtype diffuse high-grade gliomas include: (1) use caution assigning CNS WHO grade 4 (diagnosis of Glioblastoma, IDH-wildtype) to a “TERT promoter only”, histologically low-grade, IDH-wildtype tumor; (2) EGFR gene amplification and +7/−10 chromosome copy number alterations should not be used as solitary defining features for diagnosing high-grade gliomas as Glioblastoma, IDH-wildtype in patients <40 years of age; (3) Diffuse pediatric-type high-grade glioma, H3-wildtype, and IDH-wildtype should be considered in the differential diagnosis in adults, especially those <40 years of age; (4) PDGFRA alteration, EGFR alteration, or MYCN amplification count as key molecular features of Diffuse pediatric-type high-grade glioma, H3-wildtype, and IDH-wildtype only in patients <25 years. Guidelines for improved diagnosis of posterior fossa ependymal tumors include: (1) immunohistochemical demonstration of nuclear EZHIP supports classification as PF group A ependymoma; (2) a PF ependymoma with retained nuclear H3 K27me3 expression and no nuclear EZHIP overexpression for which DNA methylation profiling is not performed should be considered as PF ependymoma, “not otherwise specified”; (3) for emerging tumors not included in WHO CNS5, “not elsewhere classified” (NEC) can be added to the diagnosis. Of note, these recommendations are not formal changes to the WHO definitions and diagnostic criteria but are intended to provide diagnostic guidance in advance of WHO CNS6.

Nitro-oleic acid (OA-NO₂) is an endogenous peroxisome proliferator-activated receptor-γ (PPARγ) ligand and can activate this receptor under both physiological and pathological conditions. In this study, we explore the role and molecular mechanisms of OA-NO₂ in maintaining blood–brain barrier (BBB) integrity and enhancing neurovascular function during ischemic stroke, with a particular emphasis on the activation of endothelial PPARγ signaling pathways. Endothelial cell-selective PPARγ conditional knockout (EC-PPARγ cKO) and wild-type (WT) mice underwent 1 h middle cerebral artery occlusion (MCAO) with 1–7 days of reperfusion. Mice were treated with oleic acid (OA) or OA-NO₂ (5 mg/kg) via tail vein 2 h after MCAO. Neurobehavioral deficits were assessed on days 3, 5, and 7 after MCAO. Neuroinflammation and BBB function were assessed on days 1 or 2 after MCAO by immunohistochemistry, RT-qPCR, or Western blot analysis. Compared to OA controls, intravenous administration of OA-NO₂ led to reduced BBB leakage in ischemic brains, as indicated by a significant decrease in the extravasation of BBB tracers. This reduction in BBB leakage was also almost abolished in the EC-PPARγ cKO mice. Furthermore, OA-NO₂ treatment reduced brain infarction in stroke mice, but this protective effect was completely reversed in the EC-PPARγ cKO mice. Interestingly, OA-NO₂ treatment promoted a shift towards an anti-inflammatory microglial phenotype (M2) in the peri-infarct regions of WT mice, but not in EC-PPARγ cKO mice. Mechanistically, OA-NO₂ increased levels of major endothelial tight junction proteins in WT mice but not in EC-PPARγ cKO mice following ischemic stroke. These findings suggest that OA-NO₂ activation of endothelial PPARγ signaling cascade attenuates neurovascular injury after ischemic stroke.

Phenotypic changes in microglia have been linked to multiple neurological conditions, such as dementia, Parkinson's disease, stroke and traumatic brain injury. Consistent identification and classification of microglia is essential in understanding potential links with neurological diseases. Currently, there are several ways by which the microglial population and morphology are assessed, including manually or using open-source image analysis platforms, such as ImageJ. A microglial classification module for the HALO digital pathology platform has been developed for this purpose but has not yet been validated within the literature. The current study therefore conducted a comparison of the performance of this HALO module to manual microglial analysis and to automated analysis via ImageJ using both human and rat brain tissue. In 5 μm thick human tissue, total and activated microglia/mm² counted by HALO showed strong positive correlations with both manual and ImageJ counts. HALO did not differ from the other methods for total microglia counts; however, Halo did differ from both manual and ImageJ methods in the number of activated microglia detected within the substantia nigra. In 20 μm rat tissue, total counts derived from HALO showed moderate positive correlations with both manual and ImageJ counting; however, activated counts on Halo were not positively correlated with any method. To our knowledge, this is the first study to systematically compare the Halo module to other common methods of microglia analysis. When applied to 5 μm tissue, the Halo module is comparable to manual counting and to automated analysis on ImageJ. However, when analyzing thicker tissue, Halo struggles to perform in line with these other methods, particularly for counts of activated microglia, likely due to increased cell density and the morphological complexity of microglia. These results highlight the importance of carefully tailoring image analysis parameters on automated counting methods to suit the needs of the tissue.

The ISN is looking for a group of young motivated neuropathologists to promote the specialty via the ISN website. If you are interested in participating, please contact Audrey Rousseau ([email protected]) or Monika Hofer ([email protected]).

The International Congress of Neuropathology (ICN) will be held in Edinburgh, Scotland, in 2027 (ICN27). The Congress President will be Prof Colin Smith and the ICN27 will be hosted by the British Neuropathological Society (BNS).

“On behalf of the British Neuropathological Society I am delighted to extend a warm invitation to all our colleagues across the world to join us in Edinburgh for the International Congress of Neuropathology 2027. Edinburgh is an easily accessible centre, surrounded by 1000 years of living history. We will develop a strong academic programme covering all aspects of neuropathology with world leading plenary speakers, supported by a social programme highlighting some of Edinburgh's historic charms. For those wishing to explore further, Edinburgh offers access to many of Scotland's highlights, be it touring the Highlands, sampling our famous whisky or golfing on some of our picturesque courses. I do hope you will be able to join us for what I am sure will be a memorable meeting showcasing the best in international neuropathology.

Colin Smith

Congress President ISN 2027”

Summary report for ICN23 Berlin (our most recent International Congress of Neuropathology, September 2023) now available in the Society's journal Brain Pathology (see link: https://doi.org/10.1111/bpa.13249).

We are delighted to start the bidding process for holding the 2031 XXII International Congress of Neuropathology (ICN). As you know, the 2027 XXI ICN Congress will be in Edinburgh and we now need to think ahead to 2031 and find a new home for our much-loved congress.

The Invitation Letter calling for bids and outlining the process can be found on the ISN website (www.intsocneuropathol.com). Please note that the deadline is the 31st August 2025.

The 7th Quadrennial Meeting of the World Federation of Neuro-Oncology Societies will be held in conjunction with the 30th Annual Meeting & Education Day of the Society for Neuro-Oncology November 19-23, 2025 in Honolulu, Hawaii.

Brain Pathology has joined Wiley's Open Access portfolio as of January 2021. As a result, all submissions are subject to an Article Publication Charge (APC) if accepted and published in the journal. ISN members are eligible for a 10% discount off the Open Access APC. For more information on the fees, please click here.

Free resource: digital microscopy platform for neurodegenerative diseases curated in Munich. Prof Jochen Herms and his team have been setting up a digital microscopy platform for neurodegenerative diseases in their department in Munich. Registration is free. ISN members and int

Sphingolipids are essential, complex lipids that are abundant in the cell membranes of eukaryotic cells, particularly concentrated in the myelin and neuronal membranes of the central nervous system (CNS). These lipids are crucial components of the cell membrane, affecting their structure and fluidity, and thus regulating various biological processes, including signal transduction, cell differentiation, apoptosis, and autophagy. The metabolic pathways of sphingolipids are highly complex and conserved, and this metabolic process can produce multiple metabolites. Metabolites such as ceramide (Cer) and sphingosine-1-phosphate (S1P) are vital in CNS signaling, affecting neurodevelopment, myelination, and synaptic plasticity. Thus, disruption of sphingolipid metabolism is closely related to neurological disorders. This article provides the latest studies concerning the known features of sphingolipid and sphingolipid metabolism, highlighting its physiological and pathological roles in the CNS.

Multiple sclerosis (MS) is a chronic neuroinflammatory disease that progresses to a stage marked by irreversible neurological decline and widespread neurodegeneration. Necroptosis, a regulated form of cell death primarily triggered by tumor necrosis factor (TNF), has been implicated in neuronal loss in progressive MS. The Endosomal Sorting Complex Required for Transport (ESCRT) machinery, essential for plasma membrane repair and vesicle trafficking, is known to counteract necroptosis in non-neural cells. In this study, we investigated whether ESCRT dysfunction contributes to neurodegeneration in the MS cortex. We identified a significant dysregulation of ESCRT-III complex components, particularly VPS4B and CHMP2A, in neurons of MS cortical grey matter. This dysregulation correlated with reduced neuronal density and increased meningeal inflammation. Notably, both demyelinated and normal-appearing grey matter showed decreased VPS4B, while CHMP2A loss was more restricted to areas of demyelination. These findings suggest that impaired ESCRT-III function may increase neuronal vulnerability to necroptosis and contribute to disease progression in MS. Our results highlight a novel pathway linking neuroinflammation, ESCRT dysfunction, and neuronal death, with potential therapeutic implications for neuroprotection in progressive MS.

The type C variant (TDP-C) of FTLD-TDP exhibits unique features, not shared by types A and B, namely the invariable and frequently asymmetric predilection for the anterior temporal lobes (ATL). Depending on the direction of hemispheric asymmetry, the associated clinical features include word comprehension impairment, associative agnosia, and behavioral abnormalities. Current research on TDP-C aims to explore the factors that underlie the selective targeting of the ATL and, more specifically, the cellular details that undermine the behavioral and cognitive functions of this region. Abnormal TDP-C neurites have recently been shown to represent heterodimers with annexin A11 (ANXA11). This feature, not shared by TDP-A or -B, may explain the unique predilection of TDP-C for the ATL. To further explore the subcellular distribution of the pathology, paraffin-embedded sections were stained using fluorescent antibodies for the dendritic marker MAP2 and phosphorylated TDP-43 (pTDP) or ANXA11. Results indicated that approximately half of pTDP/ANXA11 neurites co-localized with MAP2. The actual overlap during life may be much higher but decreased at autopsy through dendritic loss due to prolonged neurodegeneration. The potentially selective and progressive dendritic pathology of TDP-C, quite unique among neurodegenerative entities, may underlie the distinctive perturbation of cortical integrative computations.

Brain tumors are the most common solid tumors in children and young adults, but the scarcity of large histopathology datasets has limited the application of computational pathology in this group. This study implements two weakly supervised multiple-instance learning (MIL) approaches on patch features obtained from state-of-the-art histology-specific foundation models to classify pediatric brain tumors in hematoxylin and eosin whole slide images (WSIs) from a multi-center Swedish cohort. WSIs from 540 subjects (age 8.5 ± 4.9 years) diagnosed with brain tumors were gathered from the six Swedish university hospitals. Instance (patch)-level features were obtained from WSIs using three pre-trained feature extractors: ResNet50, UNI, and CONCH. Instances were aggregated using attention-based MIL (ABMIL) or clustering-constrained attention MIL (CLAM) for patient-level classification. Models were evaluated on three classification tasks based on the hierarchical classification of pediatric brain tumors: tumor category, family, and type. Model generalization was assessed by training on data from two of the centers and testing on data from four other centers. Model interpretability was evaluated through attention mapping. The highest classification performance was achieved using UNI features and ABMIL aggregation, with Matthew's correlation coefficient of 0.76 ± 0.04, 0.63 ± 0.04, and 0.60 ± 0.05 for tumor category, family, and type classification, respectively. When evaluating generalization, models utilizing UNI and CONCH features outperformed those using ResNet50. However, the drop in performance from the in-site to out-of-site testing was similar across feature extractors. These results show the potential of state-of-the-art computational pathology methods in diagnosing pediatric brain tumors at different hierarchical levels with fair generalizability on a multi-center national dataset.

Pediatric low-grade gliomas (pLGG) comprise 35% of all brain tumors. Despite favorable survival, patients experience significant morbidity from disease and treatments. A deeper understanding of pLGG biology is essential to identify novel, more effective, and less toxic therapies. We utilized single-cell RNA sequencing (scRNA-seq), spatial transcriptomics, and cytokine analyses to characterize and understand tumor and immune cell heterogeneity of pilocytic astrocytoma (PA) and ganglioglioma (GG). scRNA-seq revealed tumor and immune cells within the tumor microenvironment (TME). Tumor cell subsets include both progenitor and mature cell populations. Immune cells included myeloid and lymphocytic cells. There was a significant difference between the prevalence of two major myeloid subclusters between PA and GG. Bulk and single-cell cytokine analyses evaluated the immune cell signaling cascade with distinct immune phenotypes among tumor samples. KIAA1549-BRAF tumors appeared more immunogenic, secreting higher levels of immune cell activators and chemokines, compared to BRAF V600E tumors. Spatial transcriptomics revealed the differential gene expression of these chemokines and their location within the TME. A multi-pronged analysis demonstrated the complexity of the PA and GG TME and differences between genetic drivers that may influence their response to immunotherapy. Further investigation of immune cell infiltration and tumor-immune interactions is warranted.