Acta Neuropathologica Communications最新文献

Studies of the mitochondrial respiratory chain (MRC) have given important insights into the pathology of mitochondrial and neurodegenerative disorders. Immunohistochemical methods for staining MRC complexes are particularly valuable for assessing quantitative changes in situ, especially in complex tissues with cellular heterogeneity, such as the brain. However, traditional approaches have notable limitations. Chromogen-based staining, while preserving tissue morphology, has been restricted to a single antigen per section, preventing co-assessment of MRC complexes and mitochondrial mass on the same section. Immunofluorescence, which allows multiplex staining of multiple targets, partially addresses this limitation but compromises tissue morphology and can be highly variable in postmortem brain samples. To address these challenges, we have established a dual-antigen, chromogen-based immunohistochemical method that allows simultaneous assessment of each MRC complex and the mitochondrial marker voltage-dependent anion channel 1 (VDAC1) on the same section. As proof of concept, we apply this method on brain tissue from patients with neurological disease caused by mutations in the mitochondrial DNA polymerase gamma (POLG). Our findings demonstrate that this approach is both reliable and robust. Moreover, this method enables more precise identification of MRC deficiencies in neurons and significantly reduces the amount of tissue required for analysis, a critical advantage when working with scarce human brain samples.

Neuroinflammation is widely posited to be a key pathogenic mechanism linking acute organophosphate (OP)-induced status epilepticus (SE) to persistent brain injury and abnormal electrical activity that contribute to epilepsy and cognitive impairment. The plasminogen activation system (PAS) promotes neuroinflammation in diverse neurological diseases but whether it is activated following acute OP intoxication has yet to be evaluated. To address this data gap, we characterized the spatiotemporal expression patterns of multiple components of the PAS in a rat model of acute intoxication with the OP, diisopropylfluorophosphate (DFP). Adult male Sprague Dawley rats administered DFP (4 mg/kg, sc), atropine sulfate (2 mg/kg, im) and 2-pralidoxime (25 mg/kg, im) went into SE that persisted for hours. One day after acute DFP-induced SE, plasmin activity and protein concentrations of plasminogen activator inhibitor-1 (PAI-1) in the plasma were increased, though not significantly. In contrast, acute DFP intoxication significantly increased brain levels of PAI-1, tissue-type plasminogen activator (tPA), urokinase plasminogen activator (uPA), and transcripts of TGF-β in a time- and region-dependent manner. In the cortex and hippocampus, quantification of PAI-1, tPA, and uPA by ELISA indicated significantly increased levels at 1 day post-exposure (DPE). PAI-1 and uPA returned to control values by 7 DPE while tPA protein remained elevated at 28 DPE. Immunohistochemistry detected elevated PAI-1 expression in the DFP brain up to 28 DPE. Co-localization of PAI-1 with biomarkers of neurons, microglia, and astrocytes demonstrated that PAI-1 localized predominantly to a subpopulation of astrocytes. Cytologically, PAI-1 localized to astrocytic end feet, but not adjacent neurovascular endothelium. Electron microscopy revealed neuronal metabolic stress and neurodegeneration with disruption of adjacent neurovascular units in the hippocampus post-DFP exposure. These data indicate that acute DFP intoxication altered PAS expression in the brain, with aberrant PAI-1 expression in a subset of reactive astrocyte populations.

Gliomas are the most common primary brain tumors and a major source of mortality and morbidity in adults and children. Recent genomic studies have identified multiple molecular subtypes; however metabolic characterization of these tumors has thus far been limited. We performed metabolic profiling of 114 adult and pediatric primary gliomas and integrated metabolomic data with transcriptomics and DNA methylation classes. We identified that pediatric tumors have higher levels of glucose and reduced lactate compared to adult tumors regardless of underlying genetics or grade, suggesting differences in availability of glucose and/or utilization of glucose for downstream pathways. Differences in glucose utilization in pediatric gliomas may be facilitated through overexpression of SLC2A4, which encodes the insulin-stimulated glucose transporter GLUT4. Transcriptomic comparison of adult and pediatric tumors suggests that adult tumors may have limited access to glucose and experience more hypoxia, which is supported by enrichment of lactate, 2-hydroxyglutarate (2-HG), even in isocitrate dehydrogenase (IDH) wild-type tumors, and 3-hydroxybutyrate, a ketone body that is produced by oxidation of fatty acids and ketogenic amino acids during periods of glucose scarcity. Our data support adult tumors relying more on fatty acid oxidation, as they have an abundance of acyl carnitines compared to pediatric tumors and have significant enrichment of transcripts needed for oxidative phosphorylation. Our findings suggest striking differences exist in the metabolism of pediatric and adult gliomas, which can provide new insight into metabolic vulnerabilities for therapy.

Cognitive impairment is a common and challenging side effect of cranial radiation therapy for brain tumors, though its precise mechanisms remain unclear. The mesocortical dopaminergic pathway, known to play a key role in cognitive function, is implicated in several neuropsychiatric disorders, yet its involvement in radiation-induced cognitive dysfunction is unexplored. Here, with using in vivo multi-electrode array recordings of both anesthetized and free-moving rats to monitor the firing activities of dopamine neurons in the ventral tegmental area (VTA) and local field potentials in both the prefrontal cortex (PFC) and VTA, as well as the immunofluorescence assays and western blotting, we report that cranial irradiation transiently altered VTA dopamine neuron firing patterns without affecting overall firing rates and led to sustained reductions in both "awake" and total dopamine neuron density. Additionally, radiation exposure impaired D2 receptor function and disrupted connectivity between the PFC and VTA. These multifaceted disruptions in the mesocortical dopamine signaling may underlie the development of radiation-induced cognitive dysfunction. These findings pave the way for novel research to prevent or reverse radiation-induced injury, ultimately improving the quality of life for brain tumor survivors.

Balamuthia mandrillaris is a rare, free-living amoeba (FLA) that causes granulomatous amoebic encephalitis, a disease with close to 90% mortality. The geographical ranges of many FLA are expanding, potentially increasing human exposure to B. mandrillaris. Here, we report a case of a 58-year-old woman with progressive neurological symptoms, ultimately diagnosed postmortem with B. mandrillaris encephalitis through plasma metagenomic next-generation sequencing (mNGS) despite negative results on both cerebrospinal fluid (CSF) mNGS and CSF PCR testing. Histologic analysis and real-time PCR (qPCR) studies on postmortem brain tissue confirmed B. mandrillaris infection with significant vascular clustering of trophozoites. Retrospective analysis of CSF mNGS data demonstrated subthreshold reads for B. mandrillaris, emphasizing the challenges of interpreting low-level pathogen signals. A systematic review of 159 published B. mandrillaris cases revealed only two reports of B. mandrillaris diagnosed using plasma mNGS, both of which also had diagnostic CSF studies. This case demonstrates the diagnostic challenges of B. mandrillaris infections, highlights its vascular tropism, and suggests that plasma mNGS may warrant evaluation as a diagnostic tool for B. mandrillaris.

Gastrointestinal (GI) dysfunctions, including constipation and delayed stomach emptying, are prevalent and debilitating non-motor symptoms of Parkinson's disease (PD). These symptoms have been associated with damage in the enteric nervous system (ENS) and the accumulation of pathogenic alpha-synuclein (α-Syn) within the GI tract. While motor deficits and dopaminergic neuron loss in the central nervous system (CNS) of the A53T mouse model are well-characterised, the temporal relationship between GI dysfunction, ENS pathology, and motor symptoms remains unclear. This study aimed to investigate functional alterations in the GI tract at the early stages of the disease, before the appearance of motor deficits, both in vivo and ex vivo. Early colonic motility deficits observed in A53T mice, measured via bead expulsion, preceded motor impairments emerged at 36 weeks. Although whole-gut transit remained unchanged, reduced faecal output was concurrent with marked colonic dysmotility at 36 weeks. Despite a lack of significant neuronal loss, a greater number of enteric neurons in A53T mice showed signs of neuronal hypertrophy and increased nuclear translocation of HuC/D proteins indicative of neuronal stress at 12 and 36 weeks. Calcium imaging revealed differential enteric neuron activity, characterised by exaggerated calcium transients at 12 weeks that normalized by 36 weeks. Furthermore, a reduction in enteric glial populations was observed as early as 12 weeks in both the ileum and colon of A53T mice. These findings provide compelling evidence that ENS pathology, including neuronal stress, disrupted calcium signalling, and glial cell loss, precedes the onset of motor symptoms and may contribute to early GI dysfunction in PD.

Background: Collision tumors, involving two distinct neoplasms in a single anatomical site, are rare. Among these, the metastasis of melanoma into an intracranial meningioma is particularly uncommon, with only four previously reported cases. Melanoma, known for its aggressive metastatic potential, contrasts sharply with the small number of collision tumor reports. The coexistence of these tumors poses diagnostic and therapeutic challenges, particularly in patients with a stable meningiomas.

Results: We present the fifth documented case of melanoma metastasizing to a meningioma, the first to include genetic analysis revealing an NRAS mutation in the melanoma. The patient, a 58-year-old man, developed a hemorrhagic transformation of a stable left frontal meningioma. Surgical resection confirmed a biphasic tumor with melanoma cells infiltrating the meningioma. Despite initial treatment with immune checkpoint inhibitors, the patient's condition progressed with widespread metastatic melanoma, ultimately leading to death.

Conclusions: The rarity of reported melanoma-to-meningioma metastasis highlights the need for further research into the genetic and pathophysiological mechanisms underlying tumor-to-tumor metastasis. Advances in genomic technologies could help identify biomarkers associated with such rare phenomena. This case also emphasizes the importance of monitoring patients with stable meningiomas and a history of melanoma for potential metastasis. Future research should explore whether prophylactic management of benign meningiomas could mitigate this risk and assess the long-term outcomes of collision tumors compared to typical metastatic brain tumors.

Nicotinamide adenine dinucleotide (NAD⁺) plays an important role in tumor progression, but its role in non-small cell lung cancer with brain metastasis (NSCLC BM) remains unclear. Herein, we investigated NAD⁺ biosynthesis targeting as a new therapeutic strategy for NSCLC BM. Therapeutic activity of nicotinamide phosphoribosyl transferase (NAMPT) inhibitors was evaluated in mouse models of NSCLC BM and using various assays such as NAD⁺ quantitation, cell viability, and apoptosis assays. To explore impact on downstream signaling, RNA sequencing was used in NAMPT inhibitor-treated and control cells, followed by validation with genetic knockdown, western blot and qRT-PCR. Expression of NAMPT and downstream proteins in human NSCLC BM and its association with patient prognosis were examined. Finally, combination of NAMPT inhibitor and cisplatin was tested in vivo. Systemic treatment with NAMPT inhibitors demonstrated intracranial activity in an NSCLC BM model. NAMPT inhibitors decreased cellular NAD levels and suppressed proliferation and invasion, and induced apoptosis in NSCLC cells. Supplementation with NAD⁺ precursor NMN rescued these NAMPT inhibitor effects. Mechanistically, disruption of NAMPT-mediated NAD⁺ biosynthesis suppressed TGF-β1/Smads/RAB26 signaling, leading to inhibition of NSCLC cells. Expression of NAMPT/TGF-β1/Smads/RAB26 axis proteins was upregulated in NSCLC BM tissues and correlated with poor prognosis. Combining NAMPT inhibitors with cisplatin further extended the survival of NSCLC BM-bearing mice. Targeting NAD⁺ biosynthesis provides a new therapeutic strategy for NSCLC BM and can be effectively combined with cisplatin. Our studies identified the TGF-β1/Smads/RAB26 signaling downstream of NAMPT, which was targeted by NAMPT inhibition to mediate anti-cancer effects.

The fetal origins of neuropsychiatric disorders are poorly understood but have been linked to viral or inflammatory injury of the developing brain. The fetal white matter is particularly susceptible to injury as myelination, axonal growth, and deep white matter tracts become established. We have used the pigtail macaque (Macaca nemestrina) to study the maternal and fetal effects of influenza A virus (FLUAV) and Zika virus (ZIKV) infection during pregnancy, in cohorts with different time intervals between inoculation and delivery. We observed a striking histopathological alteration in a subset of astrocytes which contained granular cytoplasmic inclusions ("inclusion cells", ICs) within a specific region of the deep cerebral white matter in the fetal brains from specific FLUAV and ZIKV cohorts. Immunohistochemical and ultrastructural characteristics of ICs indicated that they are astrocytes (GFAP+) undergoing autophagocytosis (p62+) with activated lysosomes (LAMP1+, LAMP2+) and reactive changes in neighboring microglia. There was also a positive correlation between the number of ICs and LAMP1 or LAMP2 immunoreactivity in the fetal brain (LAMP1: rho 0.66; LAMP2: rho 0.54, p < 0.001 for both). Interestingly, ICs were significantly more prevalent in the 5-day FLUAV cohort and the 21-day intermediate ZIKV cohort than in controls (p < 0.005 and p = 0.04, respectively), but this relationship was not apparent in the ZIKV cohort with a shorter (2-3 days) or longer (months) time course. Virologic and immunologic assays indicated that the appearance of these cells was not linked with fetal brain infection. ICs were not observed in a macaque model of perinatal hypoxic ischemic encephalopathy. These alterations in fetal white matter are pathologically abnormal and may represent a transient neuropathologic finding that signifies a subtle brain injury in the fetus after maternal viral infection.

Pineoblastoma is a rare and aggressive malignancy that often affects pediatric populations. Accurate diagnosis is challenging due to histological overlap with other central nervous system tumors and limited molecular data. DNA methylation profiling and analysis of circulating tumor DNA (derived from both cell dissemination as well as cell-free- cfDNA) in cerebrospinal fluid (CSF) are emerging tools for precise tumor classification, in the field of pediatric central nervous system tumors. Here, we report a challenging case of a 17-year-old refugee girl with a previous diagnosis of a primitive neuroectodermal tumor. Formalin-fixed, paraffin-embedded tissue was not available for histopathological re-evaluation. However, the methylation profiling of low amount of CSF-derived DNA classified the tumor as "pineoblastoma, subtype miRNA processing altered 1, subclass A," enabling patient management. The diagnosis was later confirmed through tissue-based DNA methylation analysis of a secondary lesion, demonstrating that the epigenetic signature faithfully reflected tumor features. This case report highlights the potential of CSF-based DNA methylation profiling as a minimally invasive yet accurate diagnostic tool for pediatric CNS tumors. The concordance between CSF and tissue profiling supports the integration of liquid biopsy into diagnostic workflows, allowing for earlier diagnosis and personalized treatment strategies. However, more studies are needed to demonstrate the reliability of our approach in other CNS malignancies.