Acta Neuropathologica Communications最新文献

While neuroimaging studies have revealed notable white matter damage following mild traumatic brain injury (mTBI), the specific tracts and brain regions affected vary widely across studies. Here, we explored whether the spatial orientation of white matter tracts influences susceptibility to repeated mTBI, predicting that tracts oriented orthogonal to the axis of rotation of the head during impact (within the plane of rotation) would exhibit the most damage. Using a model of repeated rotational mTBI in mice, we acquired advanced diffusion MRI (diffusional kurtosis imaging using oscillating gradient encoding) and resting-state functional MRI (fMRI) data at baseline and 1-week post-injury. Consistent with our prediction, while both diffusivity and diffusional kurtosis decreased in the white matter of injured mice, only diffusional kurtosis revealed microstructural changes confined to tracts oriented orthogonal to the right-left axis of rotation. In addition, both region and subregion analyses showed functional connectivity (FC) deficits between regions connected via tracts running orthogonal to the rotation axis. The orientation-dependent changes in imaging metrics were validated by histopathological analyses. Females showed greater microstructural changes than males using diffusion MRI following injury, while no sex differences were detected by fMRI. Interestingly, the region-specific and subregion-specific FC analyses showed overlapping but non-identical changes in FC suggesting the utility of using both coarse and fine levels of brain parcellation for FC analyses in mTBI. These findings suggest that mTBI imaging studies may benefit from the consideration that damage after mTBI will predominate in tracts that are oriented orthogonal to the axis of rotation produced by the impact and that diffusivity and diffusional kurtosis as well as region and subregion-specific fMRI analyses can detect these changes.

Lower grade gliomas frequently harbor mutations in isocitrate dehydrogenase (IDH), which define biologically distinct tumor subtypes. Although IDH-mutant and IDH-wildtype gliomas share similar histological morphology, they display markedly different metabolic profiles that may be exploited for targeted therapy. In this study, we investigated therapeutic approaches tailored to these metabolic differences. Using capillary electrophoresis-mass spectrometry, we compared the metabolomes of engineered IDH-wildtype and IDH-mutant glioma cell models. IDH-mutant cells exhibited elevated asparagine levels and reduced glutamine and glutamate levels compared with IDH-wildtype cells. These differences were corroborated in vivo by proton magnetic resonance spectroscopy of 130 patients with diffuse gliomas, showing lower glutamine and glutamate in IDH-mutant tumors. Pharmacological depletion of asparagine with L-asparaginase, which converts asparagine to aspartate, preferentially inhibited the growth of IDH-wildtype glioma cells, and this effect was potentiated by inhibition of asparagine synthetase. In contrast, inhibition of glutamate dehydrogenase 1 (GLUD1), the enzyme catalyzing the conversion of glutamate to α-ketoglutarate, selectively suppressed proliferation of IDH-mutant glioma cells by inducing reactive oxygen species accumulation and apoptosis. In vivo, L-asparaginase suppressed tumor growth in xenografted IDH-wildtype gliomas, whereas GLUD1 inhibition significantly reduced tumor growth in IDH-mutant glioma xenografts. These findings reveal distinct amino acid metabolic vulnerabilities defined by IDH mutation status and identify L-asparaginase and GLUD1 inhibition (via R162) as promising, mutation-specific therapeutic strategies. L-asparaginase demonstrated potent antitumor activity against IDH-wildtype gliomas, while GLUD1 inhibition selectively suppressed IDH-mutant gliomas both in vitro and in vivo. These results highlight the clinical potential of targeting amino acid metabolism in gliomas and provide a strong rationale for translating these mutation-specific approaches into future clinical trials.

Central nervous system (CNS) macrophages play key roles in viral neuropathogenesis and immune surveillance, yet their trafficking and trafficking dynamics between the CNS and peripheral lymphoid tissues remain poorly understood. To address this gap, we used intracisternal (i.c.) injection of fluorescent-superparamagnetic iron oxide nanoparticles (SPION) in SIV-infected macaques that we found labeled CNS CD68⁺CD163⁺CD206⁺ perivascular, meningeal, and choroid plexus (CP) macrophages. SPION⁺CD163⁺ macrophages were also detected in the optic nerves and cribriform area-potential routes of macrophage egress from the CNS. CD163⁺SPION⁺ macrophages labeled in the CNS were identified in the deep cervical lymph node (dCLN) and dorsal root ganglia (DRG). SPION⁺ CD163⁺ macrophages appeared in both the CNS and the periphery as early as 24 h post i.c. inoculation, decreasing over time in the CNS of non-infected animals but accumulating with SIV infection. A trend toward greater numbers of SPION ⁺ macrophages that traffic out of the CNS was observed in non-infected animals, a pattern not seen with SIV infection. Productively infected SPION⁺ cells were found in the CNS and dCLN of infected animals 7-28 days post i.c. injection. These findings support a model in which SPION ⁺ macrophages, some of which harbor virus, traffic between the CNS and peripheral lymphoid tissues. This is discussed with regard to HIV infection of the CNS and reseeding of the periphery with CNS virus.

Intertumoral heterogeneity in glioblastoma-driven by both genomic and transcriptomic variation-complicates our understanding of how different tumor cell populations contribute to disease progression. Infiltrating tumor cells, which invade surrounding brain tissue and evade surgical resection, are thought to play a central role in recurrence. To address this, we aimed to characterize the gene expression profiles and cellular states of infiltrative tumor cells in glioblastoma. We performed high-plex spatial transcriptomics using the CosMx Spatial Molecular Imager (NanoString) on tumor tissue from eight glioblastoma patients. Formalin-fixed paraffin-embedded samples were selected to capture both the tumor core and invasive margin. A targeted panel of 1,000 genes enabled spatially resolved gene expression profiling at single-cell resolution, allowing precise identification and localization of malignant and non-malignant cell states. We show that malignant cells can be distinguished from non-malignant populations by using patient-specific clustering. Based on this annotation, we identified several known malignant states-including AC-, OPC-, NPC-, and MES-like cells-as well as a recently characterized glial-progenitor (GPC)-like state. This population co-expressed genes associated with both astrocytic and oligodendrocyte progenitor lineages and was found to be more proliferative than the traditional AC-like state. The GPC-like state was most enriched in the classical glioblastoma subtype and was strongly associated with EGFR amplification or mutation. Spatial analyses investigating malignant differences between tumor and infiltrated tissue showed heterogeneous infiltration patterns across patients. In the most extreme case, the dominant GPC-like population in the tumor core gave way to increased proportions of AC-like cells in infiltrated regions. Our study highlights diverging infiltration patterns across glioblastoma tumors, with indications of a GPC-like to AC-like transition occurring in classical-subtyped tumors. This shift is associated with a decrease in cell proliferation and may have implications for clinical treatment.

Recent RNA-sequencing studies have established a reactive molecular signature and highlighted substantial regional diversity of microglia, underscoring their involvement in neurodegenerative proteinopathies. However, the implications of these findings have not been fully elucidated at the protein expression level in neuropathological settings, especially when comparing different proteinopathies. Using FFPE tissue from postmortem human brains with neuropathologically confirmed sporadic Creutzfeldt-Jakob disease, subtype MM1 (n = 5, formic acid-treated tissue), Alzheimer's disease, Braak stage VI (n = 5), and control brains with no noteworthy pathological changes (n = 2), we (1) verify the reactive microglial signature at the protein expression level utilizing spatial protein profiling, (2) detect a disease-specific amoeboid IBA1+ cell subtype identified with digital morphological profiling, and (3) determine the correlation between identified microglia protein expression profiles and morphology within each and across all brain sample groups. As proof-of-concept, the protein expression and morphology profiling modalities can be bioinformatically integrated to quantify the reactivity of analyzed IBA1+ cells when comparing different neocortical layers (superficial grey matter, deep grey matter, and white matter) and frontal and occipital neocortex across the different diseases. We observed greater microglial reactivity in Creutzfeldt-Jakob disease compared to Alzheimer's disease, and more remarkably, greater reactivity in occipital cortex compared to frontal cortex across both diseases. Both profiling modalities additionally revealed consistent molecular and morphological differences between grey matter and white matter IBA1+ cells, with similar distributional changes observed in the layers across both diseases. This study refines the understanding of canonical, disease-specific, and brain regional features of reactive microglia in two different neurodegenerative proteinopathies and demonstrates the successful application of spatial probe-based protein profiling together with digital morphological profiling on long-term fixed FFPE and even formic acid-treated human brain tissue.

Loss of Cisd2, an iron-sulfur cluster transfer protein, results in type 2 Wolfram syndrome (WS2), a disorder associated with severe impacts on pancreatic β cell and neuronal functions. Cisd2 has been implicated in regulating intracellular Ca²⁺ signaling. However, the molecular basis and cellular consequences remain poorly understood. In this work, we demonstrate that Cisd2 intersects with intracellular Ca²⁺ dynamics at different levels, by interacting with the inositol-1,4,5-trisphosphate receptors and as a regulator of ER-mitochondria tethering. As such, loss of Cisd2 in HeLa cells results in reduced ER-mitochondrial Ca²⁺ transfer while only modestly impacting cytosolic Ca²⁺ signaling. In HeLa cells, Cisd2 deficiency promotes autophagic flux, yet has minimal impact on mitochondrial function. However, studying the impact of Cisd2 deficiency in human induced pluripotent stem cell -derived cortical neurons revealed a severe loss of glutamate-evoked Ca²⁺ responses in cytosol and associated uptake in mitochondria due to loss of ER-mitochondria contact sites. Correlating with the profound changes in cellular Ca²⁺ handling, mitochondrial function (oxygen consumption rate, ATP production, mitochondrial potential maintenance) declined severely, while autophagic flux was increased. Overall, these deficiencies further impact the resilience of Cisd2-deficient cortical neurons to cell stress as Cisd2-KO neurons were highly sensitive to staurosporine, an inducer of apoptosis. Overall, this work is one of the first to decipher the impact of Cisd2 on ER-mitochondria Ca²⁺ handling in a WS2 disease-relevant cell models, thereby revealing a unique dependence of neurons on Cisd2 for their mitochondrial health and cell stress resilience.