Co-registration of MALDI-MSI and histology demonstrates gangliosides co-localize with amyloid beta plaques in Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurological condition characterized by impaired cognitive function and behavioral alterations. While AD research historically centered around mis-folded proteins, advances in mass spectrometry techniques have triggered increased exploration of the AD lipidome with lipid dysregulation emerging as a critical player in AD pathogenesis. Gangliosides are a class of glycosphingolipids enriched within the central nervous system. Previous work has suggested a shift in a-series gangliosides from complex (GM1) to simple (GM2 and GM3) species may be related to the development of neurodegenerative disease. In addition, complex gangliosides with 20 carbon sphingosine chains have been shown to increase in the aging brain. In this study, we utilized matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) to interrogate the in situ relationship of a-series gangliosides with either 18 or 20 carbon sphingosine chains (d18:1 or d20:1, respectively) in the post-mortem human AD brain. Here, we expanded upon previous literature and demonstrated a significant decrease in the GM1 d20:1 to GM1 d18:1 ratio in regions of the dentate gyrus and entorhinal cortex in AD relative to control brain tissue. Then, we demonstrated that the MALDI-MSI profile of GM3 co-localizes with histologically confirmed amyloid beta (Aß) plaques and found a significant increase in both GM1 and GM3 in proximity to Aß plaques. Collectively, this study demonstrates a perturbation of the ganglioside profile in AD, and validates a pipeline for MALDI-MSI and classic histological staining in the same tissue sections. This demonstrates feasibility for integrating untargeted mass spectrometry imaging approaches into a digital pathology framework.

Epigenetic control of adaptive or homeostatic splicing during interval-training activities.

Interval-training activities induce adaptive cellular changes without altering their fundamental identity, but the precise underlying molecular mechanisms are not fully understood. In this study, we demonstrate that interval-training depolarization (ITD) of pituitary cells triggers distinct adaptive or homeostatic splicing responses of alternative exons. This occurs while preserving the steady-state expression of the Prolactin and other hormone genes. The nature of these splicing responses depends on the exon's DNA methylation status, the methyl-C-binding protein MeCP2 and its associated CA-rich motif-binding hnRNP L. Interestingly, the steady expression of the Prolactin gene is also reliant on MeCP2, whose disruption leads to exacerbated multi-exon aberrant splicing and overexpression of the hormone gene transcripts upon ITD, similar to the observed hyperprolactinemia or activity-dependent aberrant splicing in Rett Syndrome. Therefore, epigenetic control is crucial for both adaptive and homeostatic splicing and particularly the steady expression of the Prolactin hormone gene during ITD. Disruption in this regulation may have significant implications for the development of progressive diseases.

Co-registration of MALDI-MSI and histology demonstrates gangliosides co-localize with amyloid beta plaques in Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurological condition characterized by impaired cognitive function and behavioural alterations. While AD research historically centered around mis-folded proteins, advances in mass spectrometry techniques have triggered increased exploration of the AD lipidome with lipid dysregulation emerging as a critical player in AD pathogenesis. Gangliosides are a class of glycosphingolipids enriched within the central nervous system. Previous work has suggested a shift in a-series gangliosides from complex (GM1) to simple (GM2 and GM3) species may be related to the development of neurodegenerative disease. Additionally, complex gangliosides with 20 carbon sphingosine chains have been shown to increase in the aging brain. In this study, we utilized matrix assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) to interrogate the in situ relationship of a-series gangliosides with either 18 or 20 carbon sphingosine chains (d18:1 or d20:1 respectively) in the post-mortem human AD brain. Here, we expanded upon previous literature and demonstrated a significant decrease in the GM1 d20:1:GM1 d18:1 ratio in regions of the dentate gyrus and entorhinal cortex in AD relative to control brain tissue. Then we demonstrated that the MALDI-MSI profile of GM3 co-localizes with histologically confirmed amyloid beta (Aß) plaques and found a significant increase in both GM1 and GM3 in proximity to Aß plaques. Collectively these results support past literature and demonstrate a perturbation of the ganglioside profile in AD. Moreover, this work validates a pipeline for MALDI-MSI and classic histological staining in the same tissue sections. This demonstrates feasibility for integrating untargeted mass spectrometry imaging approaches into a digital pathology framework.

Isolated Hodgkin lymphoma of the intracranial dura: A case report and review of the literature.

Primary dural Hodgkin lymphoma (PDHL) is an extremely rare subset of Hodgkin lymphoma (HL). Its existence is controversial, as Hodgkin lymphoma is not traditionally thought to arise from the central nervous system (CNS) or its meninges and only 0.02% of patients with Hodgkin lymphoma have any CNS involvement. We report a case of a 71-year-old Caucasian man who presented with progressive fatigue and sudden onset slurred speech, disorientation, and memory loss. Brain imaging identified a large extra-axial right frontal mass, and he underwent urgent subtotal resection. Pathology and subsequent workup revealed Stage IAE classical Hodgkin lymphoma of the right frontal dura, with no extra-cranial disease or leptomeningeal spread detected. The patient was subsequently treated with ABVD chemotherapy (completed 2.5 of 4 planned cycles) and 36 Gy in 20 fractions of consolidative involved-site radiotherapy (ISRT). He has been followed for 5 years with no clinical or radiological signs of recurrence. This is the second confirmed case of intracranial PDHL reported in the literature, with the longest follow-up for any case of PDHL.

Impact of COVID-19 pandemic on neuropathology service: Experience at one Canadian center.

The COVID-19 pandemic has had a significant impact on medical services. Many countries postponed nonemergent procedures to preserve hospital resources for the unprecedented situation. Surgical backlogs caused by the COVID-19 pandemic have been evaluated by different groups. However, the impact of this pandemic on pathology and specifically neuropathology (NP) services has received limited attention. In this study, we reviewed all NP reports of the London Health Sciences Centre from January 2018 (2 years before the pandemic declaration) until the end of the year 2021. Demographic information and pathology details were collected. For tumors, site, histopathology types, and WHO grading were analyzed. In nontumoral specimens, pathological diagnoses were compared in pre- and postpandemic time. The total number of NP samples reached its lowest in April 2020, corresponding to the first Ontario provincial lockdown, and fluctuated throughout the studied period. Among the different types of NP surgical specimens, muscle and epilepsy-related specimens showed a more significant reduction, compared to neoplastic specimens. In 2020, the proportion of tumor specimens from patients older than 40 years of age increased. Similarly, the proportion of high-grade glioma and brain metastasis diagnoses also increased. Lastly, we observed a marked increase in biopsies for temporal arteritis and other inflammatory lesions.

Differential Sensitivity of the Protein Translation Initiation Machinery and mTOR Signaling to MECP2 Gain- and Loss-of-Function Involves MeCP2 Isoform-Specific Homeostasis in the Brain.

Eukaryotic gene expression is controlled at multiple levels, including gene transcription and protein translation initiation. One molecule with key roles in both regulatory mechanisms is methyl CpG binding protein 2 (MeCP2). MECP2 gain- and loss-of-function mutations lead to Rett Syndrome and MECP2 Duplication Syndrome, respectively. To study MECP2 gain-of-function, we generated stably transduced human brain cells using lentiviral vectors for both MECP2E1 and MECP2E2 isoforms. Stable overexpression was confirmed by Western blot and immunofluorescence. We assessed the impact of MeCP2E1-E2 gain-of-function on the MeCP2 homeostasis regulatory network (MECP2E1/E2-BDNF/BDNF-miR-132), mTOR-AKT signaling, ribosome biogenesis, markers of chromatin structure, and protein translation initiation. We observed that combined co-transduction of MeCP2 isoforms led to protein degradation of MeCP2E1. Proteosome inhibition by MG132 treatment recovered MeCP2E1 protein within an hour, suggesting its induced degradation through the proteosome pathway. No significant change was detected for translation initiation factors as a result of MeCP2E1, MeCP2E2, or combined overexpression of both isoforms. In contrast, analysis of human Rett Syndrome brains tissues compared with controls indicated impaired protein translation initiation, suggesting that such mechanisms may have differential sensitivity to MECP2 gain- and loss-of-function. Collectively, our results provide further insight towards the dose-dependent functional role of MeCP2 isoforms in the human brain.

Role of DNA Methyl-CpG-Binding Protein MeCP2 in Rett Syndrome Pathobiology and Mechanism of Disease.

Rett Syndrome (RTT) is a severe, rare, and progressive developmental disorder with patients displaying neurological regression and autism spectrum features. The affected individuals are primarily young females, and more than 95% of patients carry de novo mutation(s) in the Methyl-CpG-Binding Protein 2 (MECP2) gene. While the majority of RTT patients have MECP2 mutations (classical RTT), a small fraction of the patients (atypical RTT) may carry genetic mutations in other genes such as the cyclin-dependent kinase-like 5 (CDKL5) and FOXG1. Due to the neurological basis of RTT symptoms, MeCP2 function was originally studied in nerve cells (neurons). However, later research highlighted its importance in other cell types of the brain including glia. In this regard, scientists benefitted from modeling the disease using many different cellular systems and transgenic mice with loss- or gain-of-function mutations. Additionally, limited research in human postmortem brain tissues provided invaluable findings in RTT pathobiology and disease mechanism. MeCP2 expression in the brain is tightly regulated, and its altered expression leads to abnormal brain function, implicating MeCP2 in some cases of autism spectrum disorders. In certain disease conditions, MeCP2 homeostasis control is impaired, the regulation of which in rodents involves a regulatory microRNA (miR132) and brain-derived neurotrophic factor (BDNF). Here, we will provide an overview of recent advances in understanding the underlying mechanism of disease in RTT and the associated genetic mutations in the MECP2 gene along with the pathobiology of the disease, the role of the two most studied protein variants (MeCP2E1 and MeCP2E2 isoforms), and the regulatory mechanisms that control MeCP2 homeostasis network in the brain, including BDNF and miR132.

The MeCP2E1/E2-BDNF-miR132 Homeostasis Regulatory Network Is Region-Dependent in the Human Brain and Is Impaired in Rett Syndrome Patients.

Rett Syndrome (RTT) is a rare and progressive neurodevelopmental disorder that is caused by de novo mutations in the X-linked Methyl CpG binding protein 2 (MECP2) gene and is subjected to X-chromosome inactivation. RTT is commonly associated with neurological regression, autistic features, motor control impairment, seizures, loss of speech and purposeful hand movements, mainly affecting females. Different animal and cellular model systems have tremendously contributed to our current knowledge about MeCP2 and RTT. However, the majority of these findings remain unexamined in the brain of RTT patients. Based on previous studies in rodent brains, the highly conserved neuronal microRNA "miR132" was suggested to be an inhibitor of MeCP2 expression. The neuronal miR132 itself is induced by Brain Derived Neurotrophic Factor (BDNF), a neurotransmitter modulator, which in turn is controlled by MeCP2. This makes the basis of the MECP2-BDNF-miR132 feedback regulatory loop in the brain. Here, we studied the components of this feedback regulatory network in humans, and its possible impairment in the brain of RTT patients. In this regard, we evaluated the transcript and protein levels of MECP2/MeCP2E1 and E2 isoforms, BDNF/BDNF, and miR132 (both 3p and 5p strands) by real time RT-PCR, Western blot, and ELISA in four different regions of the human RTT brains and their age-, post-mortem delay-, and sex-matched controls. The transcript level of the studied elements was significantly compromised in RTT patients, even though the change was not identical in different parts of the brain. Our data indicates that MeCP2E1/E2-BDNF protein levels did not follow their corresponding transcript trends. Correlational studies suggested that the MECP2E1/E2-BDNF-miR132 homeostasis regulation might not be similarly controlled in different parts of the human brain. Despite challenges in evaluating autopsy samples in rare diseases, our findings would help to shed some light on RTT pathobiology, and obscurities caused by limited studies on MeCP2 regulation in the human brain.

Neurenteric cyst secondary to lumboperitoneal shunt.

BACKGROUND: Neurenteric cysts are rare lesions that typically present in the upper thoracic and cervical spine and are occasionally found intracranially. The optimal treatment is gross total excision as subtotal/partial excisions are associated with high recurrence rates. CASE DESCRIPTION: For the past 10 years, a patient with pseudotumor cerebri required repeated lumboperitoneal (LP) shunt revisions. This resulted in multiple neuroenterogenous cysts occurring around the proximal LP subarachnoid shunt catheter, a finding likely attributable to retrograde flow from the peritoneal cavity. CONCLUSION: Unlike ventriculoperitoneal (VP) shunts and LP shunts do not contain valves, making the retrograde passage of enterogenous cells possible when abdominal pressure exceeds lumbar subarachnoid pressure, especially in the morbidly obese patient.

MECP2 Mutation Interrupts Nucleolin-mTOR-P70S6K Signaling in Rett Syndrome Patients.

Rett syndrome (RTT) is a severe and rare neurological disorder that is caused by mutations in the X-linked MECP2 (methyl CpG-binding protein 2) gene. MeCP2 protein is an important epigenetic factor in the brain and in neurons. In Mecp2-deficient neurons, nucleoli structures are compromised. Nucleoli are sites of active ribosomal RNA (rRNA) transcription and maturation, a process mainly controlled by nucleolin and mechanistic target of rapamycin (mTOR)-P70S6K signaling. Currently, it is unclear how nucleolin-rRNA-mTOR-P70S6K signaling from RTT cellular model systems translates into human RTT brain. Here, we studied the components of nucleolin-rRNA-mTOR-P70S6K signaling in the brain of RTT patients with common T158M and R255X mutations. Immunohistochemical examination of T158M brain showed disturbed nucleolin subcellular localization, which was absent in Mecp2-deficient homozygous male or heterozygote female mice, compared to wild type (WT). We confirmed by Western blot analysis that nucleolin protein levels are altered in RTT brain, but not in Mecp2-deficient mice. Further, we studied the expression of rRNA transcripts in Mecp2-deficient mice and RTT patients, as downstream molecules that are controlled by nucleolin. By data mining of published ChIP-seq studies, we showed MeCP2-binding at the multi-copy rRNA genes in the mouse brain, suggesting that rRNA might be a direct MeCP2 target gene. Additionally, we observed compromised mTOR-P70S6K signaling in the human RTT brain, a molecular pathway that is upstream of rRNA-nucleolin molecular conduits. RTT patients showed significantly higher phosphorylation of active mTORC1 or mTORC2 complexes compared to age- and sex-matched controls. Correlational analysis of mTORC1/2-P70S6K signaling pathway identified multiple points of deviation from the control tissues that may result in abnormal ribosome biogenesis in RTT brain. To our knowledge, this is the first report of deregulated nucleolin-rRNA-mTOR-P70S6K signaling in the human RTT brain. Our results provide important insight toward understanding the molecular properties of human RTT brain.

Nodular lymphoid hyperplasia in common variable immunodeficiency syndrome mimicking familial adenomatous polyposis on endoscopy.

Common variable immunodeficiency syndrome (CVID) includes a heterogeneous disorder characterized by reduced levels of IgG, IgA or IgM, and recurrent bacterial infections with normal T-cell immunity in 60% of patients. It affects the gastrointestinal tract as the largest immune organ with a wide spectrum of symptoms and signs. We present a case of nodular lymphoid hyperplasia (NLH) of the small intestine in a 31-year-old man admitted for evaluation of chronic diarrhea. Upper and lower gastrointestinal endoscopy revealed multiple polyps in the stomach, duodenum, ileum, and large intestine mimicking familial adenomatous polyposis (FAP). Although he had no history of recurrent infection, immunological profiles were in favor of CVID. We emphasize the importance of considering CVID in any patient with gastrointestinal manifestations even in the absence of recurrent bacterial infections. Diagnostic delay results in more morbidity and complications in untreated patients.

Human epidermal growth factor receptor-2 family in colorectal adenocarcinoma: correlation with survival and clinicopathological findings.

BACKGROUND AND PURPOSE: Erb-B1 (epidermal growth factor receptor, EGFR) and Erb-B2 (HER-2) are two of the best-characterized members in the EGFR pathway. In many tumor types, overexpression of these proteins is associated with enhanced malignant potential. The aim of this study was to determine the prognostic impact of EGFR and HER-2 protein expression on colorectal cancer. METHOD: Immunohistochemistry was carried out in paraffin-embedded specimens of 115 colorectal carcinomas for the assessment of EGFR and HER-2 expression. Immunostaining for EGFR was graded negative, weak or strong according to extension and staining intensity. The results were correlated with traditional clinicopathologic parameters and patients' outcome. RESULTS: The mean survival time was 64 (range 9-78) months in the EGFR-negative group, 166 (range 2-293) months in the group with a low EGFR expression, and 51 (range 4-71) months in the group with a high EGFR expression. The median survival time was 31 (range 2-114) months in the HER-2 negative group, and 30 (range 4-293) months in the HER-2 positive group. None of the clinicopathologic parameters or patient prognoses had statistically significant association with EGFR or HER-2 expression. CONCLUSION: Conventional immunohistochemistry was unable to reveal any association between EGFR or HER-2 expression and outcome predicted by the biologic role of EGFR in tumor behavior and the established prognostic role of HER-2 in breast cancer.

Yolk sac tumor of the vagina.

Malignant germ-cell tumors GCT are rare tumors of childhood accounting for less than 3% of pediatric malignancies. Endodermal sinus tumors EST form the most common histologic subtype of malignant GCT. The vagina is an extremely rare site for GCTs. An 8-month-old female was admitted with a short history of vaginal bleeding, and a mass protruding from the vagina. A mass was palpable anteriorly on rectal examination. Computed tomography showed a tumor mass posterior to the bladder. A biopsy revealed a vaginal EST. The serum alpha-fetoprotein was elevated. Vaginohysterectomy was carried out. She was subsequently referred to the oncologist for further management.