Journal of Neuropathology and Experimental Neurology最新文献

Human brain tissue studies have used a range of metrics to assess RNA quality but there are few large-scale cross-comparisons of presequencing quality metrics with RNA-seq quality. We analyzed how postmortem interval (PMI) and RNA integrity number (RIN) before RNA-seq relate to RNA quality after sequencing (percent of counts in top 10 genes [PTT], 5' bias, and 3' bias), and with individual gene counts across the transcriptome. We analyzed 4 human cerebrocortical tissue sets (1 surgical, 3 autopsy), sequenced with varying protocols. Postmortem interval and RIN had a low inverse correlation (down to r = -0.258, P < .001 across the autopsy cohorts); both PMI and RIN showed consistent and opposing correlations with PTT (up to r = 0.215, P < .001 for PMI and down to r = -0.677, P < .001 for RIN across the autopsy cohorts). Unlike PMI, RIN showed consistent correlations with measurements of 3' and 5' bias in autopsies (r = -0.366, P < .001 with 3' bias). RNA integrity number correlated with 3933 genes across the 4 datasets vs 138 genes for PMI. Neuronal and immune response genes correlated positively and negatively with RIN, respectively. Thus, different gene sets have divergent relationships with RIN. These analyses suggest that conventional metrics of RNA quality have varying values and that PMI has an overall modest effect on RNA quality.

As Alzheimer disease (AD) progresses, pathological tau spreads by cell-to-cell propagation of tau. This study aims to elucidate the impact of AD-associated post-translational modifications of tau-on-tau propagation. Tau propagation reporter constructs distinguishing donor cells from recipient cells were developed, and additional constructs were made with tau residues mutated from serine or threonine to aspartate to mimic the negative charge of a phosphorylation and/or from lysine to glutamine to mimic the charge-neutralizing effect of acetylation. Flow cytometry was used to quantify donor and recipient cells. This revealed that the mutations generally tended to reduce tau propagation compared to wildtype tau. Recombinant tau containing either wildtype or posttranslational modification mimicking mutations were used to treat Chinese hamster ovary cells or human induced pluripotent stem cell-derived neurons to quantify tau uptake, revealing that the mutations generally resulted in reduced uptake compared to wildtype tau. Surface plasmon resonance revealed that the mutations had a reduced affinity for lipoprotein receptor-related protein 1 (LRP1), a tau uptake receptor, compared to wildtype tau. Overall, these results suggest that AD-associated posttranslational modification mimicking mutations reduce the cell-to-cell propagation of tau by reducing tau uptake by recipient cells, which may be in part due to reduced binding affinity to LRP1.

Mesencephalosynapsis is characterized by a failure of the dorsal brainstem colliculi to separate into distinct lateral masses (non-cleavage, a.k.a. "fusion"). It is linked to ventriculomegaly and aqueductal stenosis but other associations have not been systematically examined. We reviewed a large cohort of fetal hydrocephalus cases to explore associations of aqueductal stenosis, mesencephalosynapsis, and other pathologies. Among 115 cases of fetal obstructive hydrocephalus (15-41 weeks gestation), mesencephalosynapsis was seen in 44 cases (38.3%). We graded the wide range of abnormal aqueductal histology; mesencephalosynapsis was associated with 67% of severe, 35% of mild, and 10% of borderline aqueductal pathologies. In 75% of cases, it was associated with other CNS anomalies, including rhombencephalosynapsis, holoprosencephaly, hemifacial microsomia, and amniotic rupture sequence. We also identified 2 cases of aqueductal stenosis associated with brainstem tegmental injury, probably ischemic in origin, without mesencephalosynapsis. Clinical and genetic associations of mesencephalosynapsis included diabetic embryopathy, amniotic rupture sequence, chromosomal abnormalities, and mutations in TBCD132, FRAS1, and NECTIN1. This is the largest review of the histology of fetal aqueductal stenosis to date. We conclude that mesencephalosynapsis points to a defect in embryonic brainstem patterning and may be isolated, associated with other malformations, and that it is found in heritable and non-heritable conditions.

Ischemic stroke results in inhibition of axonal regeneration but the roles of fibrinogen (Fg) in neuronal signaling and energy crises in experimental stroke are under-investigated. We explored the mechanism of Fg modulation of axonal regeneration and neuronal energy crisis after cerebral ischemia using a permanent middle cerebral artery occlusion (MCAO) rat model and primary cortical neurons under low glucose-low oxygen. Behavioral tests assessed neurological deficits; immunofluorescence, immunohistochemistry, and Western-blot analyzed Fg and protein levels. Fluo-3/AM fluorescence measured free Ca2+ and ATP levels were gauged via specific assays and F560nm/F510nm ratio calculations. Mito-Tracker Green labeled mitochondria and immunoprecipitation studied protein interactions. Our comprehensive study revealed that Fg inhibited axonal regeneration post-MCAO as indicated by reduced GAP43 expression along with elevated free Ca2+, both suggesting an energy crisis. Fg impeded mitochondrial function and mediated impairment through the EGFR/Ca2+ axis by trans-activating EGFR via integrin αvβ3 interaction. These results indicate that the binding of Fg with integrin αvβ3 leads to the trans-activation of the EGFR/Ca2+ signaling axis thereby disrupting mitochondrial energy transport and axonal regeneration and exacerbating the detrimental effects of ischemic neuronal injury.

Ischemic strokes pose serious risks to human health. We aimed to elucidate the function of NOD-like receptor X1 (NLRX1) in a rat middle cerebral artery occlusion (MCAO)-induced cerebral ischemia/reperfusion injury (CIRI) model and in an oxygen-glucose deprivation/reperfusion (OGD/R)-treated human microglial cell line (HMC3) model. Following NLRX1 upregulation, infarct volumes were measured with 2,3,5-triphenyltetrazolium chloride staining and pathological examination was conducted with hematoxylin-eosin staining. Results suggested that levels of NLRX1 were decreased in brain tissue of MCAO rats and in OGD/R-stimulated HMC3 cells. NOD-like receptor X1 overexpression mitigated the neuronal damage, reduced tumor necrosis factor-α and interleukin-6 expression, alleviated microglial activation, and induced autophagy in vivo and in vitro. Additionally, a coimmunoprecipitation assay indicated that NLRX1 bound to autophagy-related gene 5 (ATG5) to elevate ATG5 expression in HMC3 cells. Further, the elevated NLR family pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD, and cleaved caspase 1 expression in MCAO rats and HMC3 cells with OGD/R induction was reduced after NLRX1 upregulation. Importantly, ATG5 depletion abrogated the effects of NLRX1 elevation on NLRP3 inflammasome signaling. These results indicate that NLRX1 promotes autophagy and inactivates NLRP3 inflammasome signaling by binding ATG5 in experimental cerebral ischemia. These data may help the development of novel therapeutic strategies for ischemic stroke.

Pilocytic astrocytomas (PAs) are benign grade 1 gliomas according to the World Health Organization (WHO). They are common in children but rare in adults in whom they may have a worse prognosis. Pediatric PAs are usually associated with dysregulation of the mitogen-activated protein kinase (MAPK) pathway, often involving BRAF alterations such as the KIAA1549::BRAF (K-B) fusion or V600E mutation. We investigated the molecular characteristics of adult PA using gene-targeted next-generation sequencing and specific gene tests, including for K-B fusion, TERT promoter, and FGFR1 hotspot mutations. The most frequent molecular alterations detected involved the MAPK pathway, particularly affecting BRAF and NF1 genes (55%). The prevalence of the K-B fusion (>40%) was higher than previously reported, likely due to challenges in detecting it. We identified molecular alterations in some cases that raised the differential diagnosis of other tumor types, revealing limitations in the 2021 WHO classification for adult PA. After removing other diagnostic types that may mimic PA histology, no adult patients with a diagnosis of PA and K-B fusion died after more than 10 years of mean follow-up. These findings suggest that, similar to pediatric cases, PA in adults may be driven by a single molecular hit, where the K-B fusion is not related to poor outcome.

Although Alzheimer disease neuropathologic change (ADNC) is the most common pathology underlying clinical dementia, the presence of multiple comorbid neuropathologies is increasingly being recognized as a major contributor to the worldwide dementia burden. We analyzed 1051 subjects with specific combinations of isolated and mixed pathologies and conducted multivariate logistic regression analysis on a cohort of 4624 cases with mixed pathologies to systematically explore the independent cognitive contributions of each pathology. Alzheimer disease neuropathologic change and limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC) were both associated with a primary clinical diagnosis of Alzheimer disease (AD) and were characterized by an amnestic dementia phenotype, while only ADNC associated with logopenic variant primary progressive aphasia (PPA). In subjects with ADNC and comorbid LATE-NC, Lewy body disease, and/or cerebrovascular disease, the clinical phenotype was usually diagnosed during life as "Probable AD." Conversely, the combination of ADNC with frontotemporal lobar degeneration with TDP-43, progressive supranuclear palsy (PSP), or corticobasal degeneration (CBD) resulted in a mixed clinical picture, with variable features of amnestic dementia, PPA subtypes, behavioral variant FTD, PSP syndrome, and CBD syndrome. These findings elucidate the cumulative effects of mixed pathologies and provide insights into interactions between neurodegenerative pathologies contributing to a variety of clinical dementia presentations.

Efficient histopathological diagnosis of central nervous system infections can be challenging but is critical for therapeutic decision making in cases for which less invasive blood or cerebrospinal fluid testing has been unrevealing. A wide variety of bacteria, fungi, viruses, and parasites can cause infections, particularly in immunocompromised individuals. Histological findings may be nonspecific or overlap with noninfectious inflammatory conditions. To minimize wasted tissue and time, a systematic approach is recommended in which: (1) relevant patient history (eg, comorbidities, travel and other exposures, and immune status) and radiological findings are reviewed, (2) a preliminary differential diagnosis based on this information and on inflammatory patterns and visualization of potential microorganisms on hematoxylin and eosin stains is generated, (3) special stains, immunohistochemistry, in situ hybridization, or molecular testing (pathogen-specific or broad-spectrum) are used for confirmation and further classification, and (4) correlation with culture results and other laboratory testing is performed to arrive at a final integrated diagnosis. Discrepancies between molecular and histological findings are often due to contamination and require careful evaluation to avoid treatment of false positives. Consultation with infectious disease pathologists or public health reference laboratories may be needed to confirm diagnoses of unusual organisms or when specialized testing is required.