Search

Cerebellar neurodegeneration is a classical feature of ataxia telangiectasia (A-T), an autosomal recessive condition caused by loss-of-function mutation of the ATM gene, a gene with multiple regulatory functions. The increased vulnerability of cerebellar neurones to degeneration compared to cerebral neuronal populations in individuals with ataxia telangiectasia implies a specific importance of intact ATM function in the cerebellum. We hypothesised that there would be elevated transcription of ATM in the cerebellar cortex relative to ATM expression in other grey matter regions during neurodevelopment in individuals without A-T. Using ATM transcription data from the BrainSpan Atlas of the Developing Human Brain, we demonstrate a rapid increase in cerebellar ATM expression relative to expression in other brain regions during gestation and remaining elevated during early childhood, a period corresponding to the emergence of cerebellar neurodegeneration in ataxia telangiectasia patients. We then used gene ontology analysis to identify the biological processes represented in the genes correlated with cerebellar ATM expression. This analysis demonstrated that multiple processes are associated with expression of ATM in the cerebellum, including cellular respiration, mitochondrial function, histone methylation, and cell-cycle regulation, alongside its canonical role in DNA double-strand break repair. Thus, the enhanced expression of ATM in the cerebellum during early development may be related to the specific energetic demands of the cerebellum and its role as a regulator of these processes.

BackgroundAccurate identification of brain tumour molecular subgroups is increasingly important. We aimed to establish the most accurate and reproducible ependymoma subgroup biomarker detection techniques, across 147 cases from International Society of Pediatric Oncology (SIOP) Ependymoma II trial participants, enrolled in the pan-European “Biomarkers of Ependymoma in Children and Adolescents (BIOMECA)” study.MethodsAcross six European BIOMECA laboratories we evaluated epigenetic profiling (DNA methylation array); immunohistochemistry (IHC) for nuclear p65-RELA, H3K27me3, and Tenascin-C; copy number analysis via FISH and MLPA (1q,CDKN2A), and MIP and DNA methylation array (genome-wide copy number evaluation); analysis ofZFTA-andYAP1-fusions by RT-PCR and sequencing, Nanostring and break-apart FISH.ResultsDNA Methylation profiling classified 65.3% (n=96/147) of cases as EPN-PFA and 15% (n=22/147) as ST-ZFTA fusion-positive. Immunohistochemical loss of H3K27me3 was a reproducible and accurate surrogate marker for EPN-PFA (sensitivity 99-100% across three centres). IHC for p65-RELA, FISH, and RNA-based analyses effectively identifiedZFTA-andYAP1-fused supratentorial ependymomas. Detection of 1q gain using FISH exhibited only 57% inter-centre concordance and low sensitivity and specificity whilst MIP, MLPA and DNA methylation-based approaches demonstrated greater accuracy.ConclusionsWe confirm, in a prospective trial cohort, that H3K27me3 immunohistochemistry is a robust EPN-PFA biomarker. Tenascin-C should be abandoned as a PFA marker. DNA methylation and MIP arrays are effective tools for copy number analysis of 1q gain, 6q andCDKN2Aloss whilst FISH is inadequate. Fusion detection was successful, but rare novel fusions need more extensive technologies. Finally, we propose test sets to guide future diagnostic approaches.Key pointsWe evaluated and cross-validated ependymoma biomarkers in a large prospective clinical trial cohort.Accurate biomarker evaluation is critical to the success of clinical trials and patient care.We propose core and core+biomarker test sets for future molecular stratification.Importance of the StudyHigh-risk paediatric ependymoma has a poor prognosis and is devastating at relapse. Molecularly defined ependymoma types need to be accurately and reliably linked to biomarkers to predict clinical outcomes and design clinical trials. Here, we evaluated and cross-validated ependymoma biomarkers in a large prospective clinical trial cohort highlighting the importance of systematic evaluation of different methods. We provide evidence to guide test selection to support the molecular stratification of paediatric ependymoma and deliver insights into the rationalisation of biomarkers for use in resource-limited settings.

Background SIOP Ependymoma I was a non-randomised trial assessing event free and overall survival (EFS/OS) of non-metastatic intracranial ependymoma in children aged 3–21 years treated with a staged management strategy. A further aim was to assess the response rate (RR) of subtotally resected (STR) ependymoma to vincristine, etoposide, and cyclophosphamide (VEC). We report final results with 12-year follow-up and post hoc analyses of recently described biomarkers. Methods Seventy-four participants were eligible. Children with gross total resection (GTR) received radiotherapy, whilst those with STR received VEC before radiotherapy. DNA methylation, 1q, hTERT, ReLA, Tenascin-C, H3K27me3, and pAKT status were evaluated. Results Five- and ten-year EFS was 49.5% and 46.7%, OS was 69.3% and 60.5%. GTR was achieved in 33/74 (44.6%) and associated with improved EFS (P = .003, HR = 2.6, 95% confidence interval (CI) 1.4–5.1). Grade 3 tumours were associated with worse OS (P = .005, HR = 2.8, 95%CI 1.3–5.8). 1q gain and hTERT expression were associated with poorer EFS (P = .003, HR = 2.70, 95%CI 1.49–6.10 and P = .014, HR = 5.8, 95%CI 1.2–28) and H3K27me3 loss with worse OS (P = .003, HR = 4.6, 95%CI 1.5–13.2). Methylation profiles showed expected patterns. 12 participants with STR did not receive chemotherapy; a protocol violation. However, best chemotherapy RR was 65.5% (19/29, 95%CI 45.7–82.1), exceeding the prespecified 45%. Conclusions Participants with totally resected ependymoma had the best outcomes. RR of STR to VEC exceeded the pre-specified efficacy criterion. However, cases of inaccurate stratification highlighted the need for rapid central review. 1q gain, H3K27me3 loss, and hTERT expression were all associated with poorer survival outcomes.

Observational studies with long-term follow-up of patients with primary central nervous system lymphoma (PCNSL) are scarce. Patient data over a period of four decades were retrospectively analysed from databases at Not-tingham University Hospitals Trust, UK. The cohort was delineated by two distinct therapeutic eras; the first from 01/01/1982 to 31/12/2010 (n = 147) and the second 01/01/2011 to 31/07/2020 (n = 125). The median age at diagnosis was significantly older in the second era compared to the first (69 and 65 years respectively, P = 0·003). The 3-, 6-and 12-month overall survival (OS) rates in the second era were significantly higher compared to the first, at 85%, 77%, 62% versus 56%, 49%, 38% respectively (log-rank test P < 0·0001). On multivariate analysis, high-dose methotrexate (HD-MTX)-based induction protocols employed in the second era were associated with improved OS compared to those used in the first [hazard ratio (HR) 0·40, 95% confidence interval (CI) 0·28–0·57]. Within the second era, superior OS rates were seen with the use of intensive HD-MTX protocols (including consolidation with high-dose chemotherapy and autologous stem cell transplantation) compared to non-intensive HD-MTX schedules (HR 0·47, 95% CI 0·22–0·99). Initiating chemotherapy within 14 days of biopsy and use of rituximab were independently associated with improved OS and progression-free survival during the second era. These data suggest that prompt treatment initiation and use of intensive HD-MTX-and rituximab-based protocols have resulted in improved survival outcomes for patients.

Aims We understand little of the pathogenesis of developmental cortical lesions, because we understand little of the diversity of the cell types that contribute to the diseases or how those cells interact. We tested the hypothesis that cellular diversity and cell-cell interactions play an important role in these disorders by investigating the signalling molecules in the commonest cortical malformations that lead to childhood epilepsy, focal cortical dysplasia (FCD) and tuberous sclerosis (TS). Methods Transcriptional profiling clustered cases into molecularly distinct groups. Using gene expression data, we identified the secretory signalling molecules in FCD/TS and characterised the cell types expressing these molecules. We developed a functional model using organotypic cultures. Results We identified 113 up-regulated secretory molecules in FCDIIB/TS. The top 12 differentially expressed genes (DEGs) were validated by immunohistochemistry. This highlighted two molecules, Chitinase 3-like protein 1 (CHI3L1) and C-C motif chemokine ligand 2 (CCL2) (MCP1) that were expressed in a unique population of small cells in close proximity to balloon cells (BC). We then characterised these cells and developed a functional model in organotypic slice cultures. We found that the number of CHI3L1 and CCL2 expressing cells decreased following inhibition of mTOR, the main aberrant signalling pathway in TS and FCD. Conclusions Our findings highlight previously uncharacterised small cell populations in FCD and TS which express specific signalling molecules. These findings indicate a new level of diversity and cellular interactions in cortical malformations and provide a generalisable approach to understanding cell-cell interactions and cellular heterogeneity in developmental neuropathology.

BACKGROUND AND PURPOSE: SWI hypointense cerebral lesions have been reported in adults with the inherited cerebellar neurodegenerative disorder ataxia telangiectasia. This study aims to establish the prevalence, age-dependency, and spatial distribution of these lesions in children and young people with ataxia telangiectasia. MATERIALS AND METHODS: Participants with classic ataxia telangiectasia and matched controls underwent SWI acquisition at 3T at 1 or 2 time points. SWI hypointense lesions were manually labeled according to the Microbleed Anatomical Rating Scale. Differences in prevalence of lesion number between groups with ataxia telangiectasia and without ataxia telangiectasia were tested with the Fisher exact test, and differences in age between participants with ataxia telangiectasia with and without lesions were tested using independent samples from the Mann-Whitney U test. The relationship between age and lesion number was modeled as an exponential function. RESULTS: Analyzable SWI datasets from 17 participants with ataxia telangiectasia (with median age at first scan of 12.4 years; range, 4.6–20.2 years; 8 [47%] were female) and 22 matched healthy controls showed prevalence of SWI hypointense lesions in 41% of participants with ataxia telangiectasia and 0% in controls (P = .001, the Fisher exact test). Lesions were exclusively supratentorial and predominantly lobar. Participants with ataxia telangiectasia with SWI hypointense lesions were older than those without (median age was 15.2 years versus 9.3 years, U = 10.5, P = .014). An exponential curve described the relationship between age and lesion number (R2 = 0.67). CONCLUSIONS: SWI hypointense lesions are common in children and young people with ataxia telangiectasia, accumulating from 12 years of age onward. In contrast to cerebellar-dominant neurodegeneration in ataxia telangiectasia, SWI hypointense lesions were exclusively supratentorial. Further investigation is needed to establish the clinical relevance of these imaging-detected lesions.

The thioredoxin (Trx) system is an important enzyme family that regulates cellular redox homeostasis. Protein expression of Trx system family members has been assessed in various cancers and linked to various clinicopathological variables, disease progression, treatment response and survival outcomes but information is lacking in brain tumours. Expression of the system was therefore examined, by immunohistochemistry in different brain tumour types, adult and paediatric cases, to determine if expression was of importance to clinical outcome. Trx system proteins were expressed, to variable levels, across all brain tumour types with significant variations in expression between different tumour types/grades/regions. High Trx reductase (TrxR) expression was linked to worse prognosis across all cohorts. High cytoplasmic TrxR expression was significantly associated with adverse overall survival (OS) in adult glioblastoma (P = 0.027) and paediatric low-grade glioma (LGG) patients (P = 0.012). High expression of nuclear TrxR, cytoplasmic and nuclear Trx and Trx-interacting protein (TxNIP) was associated with improved OS in paediatric LGGs (P = 0.031, P P = 0.044 and P = 0.018, respectively). For patients with high-grade gliomas, both high cytoplasmic TrxR and Trx expression were associated with poor OS (P = 0.002 and P = 0.007, respectively). In medulloblastoma, high expression of cytoplasmic TrxR and Trx and nuclear Trx was associated with worse prognosis (P = 0.013, P = 0.033 and P = 0.007, respectively); with cytoplasmic TrxR and nuclear Trx remaining so in multivariate analysis (P = 0.009 and P = 0.013, respectively). The consistent finding that high levels of cytoplasmic TrxR are associated with a worse prognosis across all cohorts suggests that TrxR is an important therapeutic target in brain cancers.

BackgroundSIOP Ependymoma I was a non-randomised trial assessing event free and overall survival (EFS/OS) from non-metastatic intracranial ependymoma in children aged 3 to 21 years, treated with a staged management strategy. Chemotherapy efficacy in ependymoma is debated and therefore the response rate (RR) of subtotally resected (STR) ependymoma to vincristine, etoposide and cyclophosphamide (VEC) was an additional primary outcome. We report final results with 12-year follow-up and post hoc analyses of recently described biomarkers.Methods74 participants were eligible. Children with gross total resection (GTR) received radiotherapy, whilst those with STR received VEC before radiotherapy. DNA methylation and 1q status were evaluated, alongside hTERT, ReLA, Tenascin-C, H3K27me3 and pAKT expression.ResultsFive- and ten-year EFS was 49.5% and 46.7%, OS was 69.3% and 60.5%. GTR was achieved in 33/74 (44.6%) and associated with improved EFS (p=0.003, HR=2.6, 95% confidence interval (CI) 1.4-5.1). Grade 3 tumours were associated with worse OS (p=0.005, HR=2.8, 95%CI 1.3-5.8). 1q gain and hTERT expression were associated with poorer EFS (p=0.003, HR=2.70, 95%CI 1.49-6.10 and p=0.014, HR=5.8, 95%CI 1.2-28 respectively) and H3K27me3 loss with worse OS (p=0.003, HR=4.6, 95%CI 1.5-13.2). DNA methylation profiles showed expected patterns. 12 participants with STR did not receive chemotherapy; a protocol violation. However, chemotherapy RR was 65.5% (19/29, 95%CI 45.7-82.1), exceeding a prespecified 45% RR.ConclusionsRR of STR to VEC exceeded the pre-specified criterion for efficacy. However, cases of inaccurate treatment stratification highlighted the need for rapid central review. Prognostic associations for 1q gain, H3K27me3 and hTERT were confirmed.

In this study, we report three paediatric cases of Diffuse Glioneuronal Tumours with Oligodendroglioma-like features and Nuclear Clusters (DGONC).

The identification and validation of prognostic and diagnostic biomarkers is a key element of The SIOP Ependymoma II trial, realised through the Biomarkers of Ependymoma in Children and Adolescents study (BIOMECA). BIOMECA aims to identify and validate biomarkers for prediction of outcome whilst enhancing stratification for the next generation of ependymoma trials. We outline our findings from the first 147 consecutive BIOMECA cases (posterior fossa, PF=111; supratentorial, ST=32; spinal, SP=4). We compared various methods for biomarker assessment, across six European laboratories to determine key analysis methods. Methods included: methylation-based classification (EPIC 850K DNA methylation array) (n=141); immunohistochemistry (IHC) for nuclear p65-RELA (n=32), H3K27me3 (n=115), and Tenascin-C (TNC) (n=147); copy number (CN) analysis by FISH, MLPA (1q, CDKN2A) (n=147), and MIP (molecular inversion probe) and DNA methylation array (1q, CDKN2A, 6q, 11q, 13q, 22q) (n=141); analysis of ZFTA- and YAP1-fusions by RT-PCR, sequencing, Nanostring assays and break-apart FISH (n=32). Using DNA methylation-based classification, 91% (n=101/111) of PF cases classified as PF ependymoma group A (PFA) and 69% (n=22/32) of ST cases as ST ependymoma, ZFTA fusion-positive (ZFTA). Most PFAs demonstrated inter-centre agreement for loss of H3K27me3, and were TNC positive, representing surrogate markers for PFA identification. Combinations of p65-RELA IHC, FISH analysis, and RNA-based methods were suitable to identify ZFTA- and YAP1- fused ST ependymomas. Predictive CN alterations were identified by high-resolution, quantitative MIP technology.The integration of histopathology assessment and molecular typing is now critical as the updated 2021 WHO CNS5 classification of ependymomas lists seven molecularly distinct entities. This study highlights the importance of evaluating different methods in a prospective trial cohort. Here, advanced molecular techniques represent powerful tools for the classification of ependymoma entities (DNA methylation array) and for the detection of CN alterations (MIP) and specific fusions, enabling the correct classification and identification of prognostic markers.

Background Relapse occurs in 50% of pediatric ependymoma cases and has poor prognosis. Few studies have investigated the clinical progress of relapsed disease, and treatment lacks a standardized approach. Methods and materials We analyzed 302 pediatric ependymoma cases. Tumor, demographic, and treatment variables were investigated for association with relapse risk, time to recurrence, and survival after relapse. DNA methylation profiling was performed for 135/302 cases, and predominant subgroups were EPN_PFA (n = 95) and EPN_RELA (n = 24). Chromosome 1q status was ascertained for 185/302 cases by fluorescent in-situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA), and DNA methylation profiles. Results Sixty-two percent of cases relapsed, with a median of two recurrences with no difference between posterior fossa and supratentorial locations (66% vs 55% relapse rate). One hundred seventeen (38%) cases relapsed within two years and five (2%) beyond 10 years. The late relapses were clinically heterogeneous. Tumor grade and treatment affected risk and time to relapse variably across subgroups. After relapse, surgery and irradiation delayed disease progression with a minimal impact on survival across the entire cohort. In the EPN_PFA and EPN_RELA groups, 1q gain was independently associated with relapse risk (subhazard ratio [SHR] 4.307, P = 0.027 and SHR 1.982, P = 0.010, respectively) while EPN_PFA had increased relapse risk compared with EPN_RELA (SHR = 0.394, P = 0.018). Conclusions Recurrent pediatric ependymoma is an aggressive disease with poor outcomes, for which current treatments are inadequate. We report that chromosome 1q gain increases relapse risk in common molecular subgroups in children but a deeper understanding of the underlying biology at relapse and novel therapeutic approaches are urgently needed.

Purpose To evaluate the distribution of the PAX8 transcription factor protein in ocular tissues and to investigate if immunohistochemical stains for this biomarker are useful in the diagnosis of intraocular tumors. Design Observational case series. Participants Excision and cytologic analysis specimens of 6 ciliary body epithelial neoplasms, 2 iris epithelial neoplasms, 3 retinal pigment epithelial neoplasms, 3 intraocular medulloepitheliomas, 15 uveal melanomas, and 5 uveal melanocytomas. Methods Hematoxylin-eosin and PAX8 immunohistochemical stains were performed on all specimens. In appropriate cases, bleached preparations and other immunohistochemical stains, including AE1/AE3 cytokeratin, Lin28A, and CD45, were performed. Main outcome measures Distribution of PAX8 expression in normal and neoplastic tissue. Results Strong nuclear PAX8 expression was observed in the normal corneal epithelium, iris sphincter pupillae muscle, iris pigment epithelium and dilator muscle complex, nonpigmented and pigmented epithelia of the ciliary body, lens epithelium, and a subset of retinal neurons. The normal retinal pigment epithelium and uveal melanocytes did not stain for PAX8. The ciliary body epithelial and neuroepithelial tumors (adenoma, adenocarcinoma, and medulloepithelioma) showed uniform strong nuclear PAX8 immunoreactivity. All melanocytic tumors (iris melanoma, ciliary-choroidal melanoma, and melanocytoma) and retinal pigment epithelial neoplasms showed negative results for PAX8. A subset of tumor-associated lymphocytes, most prominent in uveal melanoma, showed positive results for PAX8. The uniformity of the PAX8 staining was superior to the variable cytokeratin staining in the ciliary epithelial neoplasms and the variable Lin28A staining in malignant medulloepithelioma. The veracity of PAX8 staining was equally as robust on cytologic analysis and open-flap biopsy specimens of ciliary epithelial and iris epithelial neoplasms, melanocytoma, and melanoma. Conclusions PAX8 has proven to be a very useful diagnostic marker in a select group of adult intraocular tumors, and we highly recommend its inclusion in diagnostic antibody panels of morphologically challenging intraocular neoplasms.

Introduction Surgery and radiotherapy are established childhood ependymoma treatments. The efficacy of chemotherapy has been debated. We report final results of the SIOP Ependymoma I trial, with 12-year follow-up, in the context of a post-hoc analysis of more recently described biomarkers. Aims and Methods The trial assessed event free (EFS) and overall survival (OS) of patients aged three to 21 years with non-metastatic intracranial ependymoma, treated with a staged management strategy targeting maximum local control. The study also assessed: the response rate (RR) of subtotally resected (STR) disease to vincristine, etoposide and cyclophosphamide (VEC); and surgical operability. Children with gross total resection (GTR) received radiotherapy of 54 Gy in 30 daily fractions over six weeks, whilst those with STR received VEC before radiotherapy. We retrospectively assessed methylation and 1q status alongside hTERT, RELA, Tenascin C, H3K27me3 and pAKT expression. Results Between 1999 and 2007, 89 participants were enrolled, 15 were excluded with metastatic (n=4) or non-ependymoma tumours (n=11) leaving a final cohort of 74. Five- and ten-year EFS was 49.5% and 46.7%, OS was 69.3% and 60.5%. 1q gain was associated with poorer EFS (p=0.002, HR=3.00, 95%CI 1.49–6.10). hTERT expression was associated with worse five-year EFS (20.0% Vs 83.3%, p=0.014, HR=5.8). GTR was achieved in 33/74 (44.6%) and associated with improved EFS (p=0.006, HR=2.81, 95% confidence interval 1.35–5.84). There was an improvement in GTR rates in the latter half of the trial (1999-2002 32.4% versus 2003-2007 56.8%). Despite the protocol, 12 participants with STR did not receive chemotherapy. However, chemotherapy RR was 65.5% (19/29, 95%CI 45.7–82.1). Conclusions VEC exceeded the pre-specified RR of 45% in children over three years with STR intracranial ependymoma. However, cases of inaccurate stratification at treating centres highlights the need for rapid central review. We also confirmed associations between 1q gain, hTERT expression and outcome.

Routine childhood vaccination against measles, mumps and rubella has virtually abolished virus-related morbidity and mortality. Notwithstanding this, we describe here devastating neurological complications associated with the detection of live-attenuated mumps virus Jeryl Lynn (MuVJL5) in the brain of a child who had undergone successful allogeneic transplantation for severe combined immunodeficiency (SCID). This is the first confirmed report of MuVJL5 associated with chronic encephalitis and highlights the need to exclude immunodeficient individuals from immunisation with live-attenuated vaccines. The diagnosis was only possible by deep sequencing of the brain biopsy. Sequence comparison of the vaccine batch to the MuVJL5 isolated from brain identified biased hypermutation, particularly in the matrix gene, similar to those found in measles from cases of SSPE. The findings provide unique insights into the pathogenesis of paramyxovirus brain infections. Electronic supplementary material The online version of this article (doi:10.1007/s00401-016-1629-y) contains supplementary material, which is available to authorized users.

Medulloblastomas are the most common malignant brain tumour of childhood. Long term survival is approximately 75%, however, therapy often results in disabling outcomes and reduced quality of survival. One potential strategy to improve outcome, whilst reducing side effects, is exploiting the metabolic differences between normal and tumour cells. Under normal physiological conditions, brain cells metabolise glucose for energy. If “starved” of glucose, ketone bodies are metabolised. Mitochondrial defects in brain tumour cells obviate this metabolic flexibility resulting in glycolytic dependence. Thus, a high fat, low carbohydrate ketogenic diet (KD) may control tumour growth. We evaluated the expression of succinyl-CoA:3-oxoacid CoA transferase 1 (OXCT1) and D-β-hydroxybutyrate dehydrogenase 1 (BDH1), both involved in ketone body utilization and pyruvate kinase M2 (PKM2), essential for aerobic glycolysis, in 84 paediatric medulloblastomas by immunohistochemistry. Expression was assessed as low (20%). 70.2% showed low expression of OXCT1 and 82.5% of BDH1. Low expression of either results in an inability to metabolise ketones. 34.9% showed high expression of PKM2, increasing the Warburg effect and when combined with low expression of BDH1 (27.5%) or OXCT1 (22.0%), the optimal immunohistochemistry profile, to arrest ketone metabolism. No statistical difference was seen with gender or age. Expression of OXCT1 was significantly lower in children with a Group 4 medulloblastoma (p=0.032) when compared to other molecular subgroups (WNT, SHH and Group 3). Therefore the KD may offer a potential addition to current medulloblastoma therapies including in the prevention of disseminated recurrence characteristic of Group 4 tumours.

Ependymoma is the second most common malignant childhood brain tumour. Immunity has been implicated in recurrence but its role needs further definition to inform therapy. We profiled two independent ependymoma cohorts using RNA sequencing and DNA methylation profiling; one from fresh frozen (FF), and the other from paraffin embedded (FFPE), material. FF and FFPE cohorts contained 27 and 25 matched primary and recurrent pairs respectively. Following differential expression (DEA) and gene set enrichment analyses (GSEA), we used validated algorithms to calculate parameters associated with anti-tumour immune responses, including: immunophenoscore (IPS), cytolytic activity (CYT), and expression of immune checkpoint genes. Clustering using RNA-seq data, from primary and recurrent tumours, formed location based groups. Posterior fossa (PF) clusters formed two groups, PF1 and PF2, with expression patterns similar to EPN_PFA and EPN_PFB tumours, however, both contained predominantly EPN_PFA DNA methylation designations. GSEA comparing primary to first relapse was similar in both cohorts. PF1 demonstrated treatment independent downregulation of inflammatory responses, cytokine activity and chemotaxis. Radiotherapy treated PF1 relapses were associated with upregulation of immune related ontologies. PF2 and ST relapses showed upregulation of B- and T-cell ontologies. IPS did not change at recurrence, and was below levels associated with response to checkpoint inhibition. CYT and expression of checkpoint inhibition molecules were low. Whilst these independent datasets demonstrated shared immunological changes at recurrence; immune based algorithms indicated that activity may be inadequate to respond to immune checkpoint therapy. Other immunotherapeutic approaches may be effective, but better understanding of ependymoma’s immunological basis is essential.

Intra-tumour heterogeneity is an important diagnostic, therapeutic and prognostic challenge. Its extent and mechanism in brain tumours is incompletely understood[1]. We describe a malignant tumour with unique pathological and genetic features. Most notably the tumour contained mutations in the SMARCB1 gene (typically associated with Atypical Teratoid/Rhabdoid Tumours[2]), the H3F3A gene (typically associated with high grade glioma in children[3]) and the BRAF gene. Furthermore, there was marked heterogeneity in mutation load between different parts of the tumour. This heterogeneity has implications both for the evolution of the tumour and for its diagnosis.

Aims Published reports of brain weight in sudden infant death syndrome (SIDS) are contradictory, although several have concluded that brain weight is increased in SIDS compared with controls or reference data. This is important as, if brain weight is significantly different, it may be of diagnostic use or provide insights into the aetiology of SIDS. The aim of this study was to use a large series of well-characterized sudden unexpected infant deaths from a single centre to provide definitive data regarding this issue. Methods A retrospective review identified 1100 infants who had died suddenly and undergone a comprehensive autopsy at Great Ormond Street Hospital between 1996 and 2011. They were split into two groups: those in whom death could be explained and those whose deaths remained unexplained despite full investigation (SIDS/unexplained sudden unexpected death in infancy). Results There were 1100 cases of whom 573 (52%) were unexplained and 527 (48%) explained. Multiple regression analysis, which adjusted for sex, age and post-mortem interval, showed no difference in the ratio of brain weight : body weight between those infants dying of explained causes and those in whom no cause could be found. This finding remained true when restricting analysis to those with macroscopically normal brains. Conclusions In this large series of infants dying of both explained and unexplained causes, brain weight, once corrected for body weight, did not vary consistently with the cause of death. Brain weight cannot be used as a diagnostic indicator of the cause of death or to inform hypothetical models of the pathogenesis of SIDS.

Tubular aggregates (TAs) are cytoplasmic aggregates of membranous tubules derived from the sarcoplasmic reticulum and usually 50–70 nm in diameter [1]. They may be seen in a range of genetic myopathies, including gyrate atrophy caused by ornithine aminotransferase deficiency, periodic paralysis and two disorders of glycosylation caused by mutations in the GFPT1 and DPAGT1 genes [2, 3]. In addition, they may occur as a minor or inconsistent feature in a wide range of myopathies or be the predominant feature in idiopathic or congenital myopathies [4]. However, the mechanisms underlying TA formation remain poorly understood. We now report the development of TAs in a patient with a lipid remodelling disorder, providing new insight into the formation of TAs.

Sudden infant death syndrome (SIDS) is a leading cause of postneonatal infant death in the developed world. The cause of SIDS is unknown but several hypotheses have been proposed, including the ‘triple risk hypothesis’, which predicts that foetal development of infants who subsequently succumb to SIDS is abnormal, leaving them unable to respond appropriately to stressors. Consistent with this hypothesis, a large number of studies have reported changes in the brain in SIDS. However, on nearly every subject, the reported findings vary widely between studies. Inconsistencies in the definitions of SIDS used and in control group selection are likely to underlie much of this variability. Therefore, in our analysis, we have included only those studies that met simple criteria for both the definition of SIDS and the control group. Of the 153 studies retrieved by our review of the literature, 42 (27%) met these criteria. Foremost among the findings reported by these studies are abnormalities of the brain stem, in particular brain stem gliosis and defects of neurotransmission in the medulla. However, these studies have not identified what could be considered in diagnostic terms a causative structural or biochemical abnormality for use in routine clinical practice. An assessment of changes in the architecture and composition of brain regions and changes in neurotransmission in multiple systems in a single, large cohort of well- and consistently characterized infants dying suddenly of a range of causes is needed before the inter-relation of these different features can be appreciated.

Ependymoma is the second most common malignant brain tumour of childhood. The immune environment has been implicated in recurrence, but more research is needed to understand its role. We performed immunohistochemistry on tumour sections for the T-cell markers CD4 and CD8, B-cell marker CD20 and inflammatory markers CD45 and CD68. 55 paired primary and first recurrent tumours plus 19 non-recurrent tumours were included. Baseline clinical and DNA methylation characteristics were representative of other paediatric ependymoma cohorts. Levels of CD4, CD8 and CD20 were low within the tumour parenchyma but higher for CD45 and CD68. All markers, other than CD68, were more highly expressed in non-parenchymal than parenchymal areas (p

EPN-09. KETOLYTIC AND GLYCOLYTIC ENZYMATIC EXPRESSION IN PAEDIATRIC EPENDYMOMAS: IMPLICATION FOR KETOGENIC DIET THERAPY Lisa C.D. Storer1, Angeline Darren1, Simon M.L. Paine2, Jen Kearns3, Robert Layfield4, David A. Walker1, and Richard G. Grundy1; Children’s Brain Tumour Research Centre, School of Medicine, University of Nottingham, Nottingham, UK; Department of Neuropathology, Nottingham University Hospitals NHS Trust, Nottingham, UK; Division of Nutritional Sciences, University of Nottingham, Nottingham, UK; School of Life Sciences, University of Nottingham, Nottingham, UK Ependymoma is the second most common paediatric malignant brain tumour. Overall survival remains relatively poor, and at relapse is dismal. One potential strategy to improve outcome is exploiting the metabolic differences between normal and tumour cells. Under normal physiological conditions, brain cells metabolise glucose for energy. If “starved” of glucose, ketone bodies are metabolised. Mitochondrial defects in brain tumour cells obviate this metabolic flexibility resulting in a dependence on glycolytic energy (Warburg effect). Thus, a high fat, low carbohydrate ketogenic diet (KD) may control tumour growth. We evaluated the expression of ketolytic enzymes; succinyl-CoA:3-oxoacid CoA transferase 1 (OXCT1) and D-b-hydroxybutyrate dehydrogenase 1 (BDH1), both involved in ketone body utilization and the glycolytic enzyme; pyruvate kinase M2 (PKM2), essential for aerobic glycolysis, in 75 paediatric ependymomas by immunohistochemistry. Expression was assessed as low (,20%) or high (.20%).84%showed lowexpression of OXCT1 and 91% of BDH1. Lowexpression of either results in an inability to metabolise ketones. 82% showed high expression of PKM2, increasing the Warburg effect and when combined with low expression of BDH1 (69%) or OXCT1 (83%), the optimal immunohistochemistry profile, arrests ketone metabolism. Children aged ,36 months were 5 times less likely to show high expression of OXCT1 compared to ≥36 months (p 1⁄4 0.0321) and 7 times more likely to show high expression of PKM2 (p 1⁄4 0.0097). The KD therefore offers a potential addition to current therapies including at relapse. However, the KD would need to be carefully evaluated prior to acceptance as a useful additional therapy. Neuro-Oncology 18:iii30–iii39, 2016. doi:10.1093/neuonc/now070.8 #The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The ubiquitin–proteasome system (UPS) and macroautophagy (autophagy) are central to normal proteostasis and interdependent in that autophagy is known to compensate for the UPS to alleviate ensuing proteotoxic stress that impairs cell function. UPS and autophagy dysfunctions are believed to have a major role in the pathomechanisms of neurodegenerative disease. Here we show that continued 26S proteasome dysfunction in mouse brain cortical neurons causes paranuclear accumulation of fragmented dysfunctional mitochondria, associated with earlier recruitment of Parkin and lysine 48-linked ubiquitination of mitochondrial outer membrane (MOM) proteins, including Mitofusin-2. Early events also include phosphorylation of p62/SQSTM1 (p62) and increased optineurin, as well as autophagosomal LC3B and removal of some mitochondria, supporting the induction of selective autophagy. Inhibition of the degradation of ubiquitinated MOM proteins with continued 26S proteasome dysfunction at later stages may impede efficient mitophagy. However, continued 26S proteasome dysfunction also decreases the levels of essential autophagy proteins ATG9 and LC3B, which is characterised by decreases in their gene expression, ultimately leading to impaired autophagy. Intriguingly, serine 351 phosphorylation of p62 did not enhance its binding to Keap1 or stabilise the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor in this neuronal context. Nrf2 protein levels were markedly decreased despite transcriptional activation of the Nrf2 gene. Our study reveals novel insights into the interplay between the UPS and autophagy in neurons and is imperative to understanding neurodegenerative disease where long-term proteasome inhibition has been implicated.

Rosette-forming glioneuronal tumour of the fourth ventricle is a rarely described entity. While usually having an indolent course and hence classified as a WHO grade 1 tumour, the precise characteristics and risk of recurrence of this tumour are still unknown. In addition, the preferred treatment modality remains unclear. We present a case of an 8-year old with an early recurrence of 9 months after undergoing a sub-total resection of her tumour. Following further resection, there was no tumour present on the 3-month follow-up. In order to better characterise this tumour entity, we performed a review of the available literature on the subject. We found that it mainly affected young adults and had a female predominance. While initially these tumours were described in the fourth ventricle, the current literature suggests that they may be found in a larger variety of sites within the brain and spinal cord. There are several reports of recurrence occurring between 9 months and 10 years following surgery. There is as yet no feature of the tumour that appears to predict the risk of recurrence. This phenomenon warrants further examination to discover if there is a sub-section of tumours that is likely to recur, and until this is established, all patients should be followed up at regular intervals.

The distinguishing feature of idiopathic chronic neurodegenerative disease is its relationship to age. Even in familial disease, clinical symptoms emerge in later life. The diseases are associated with intraneuronal misfolded proteins. This implies that age-related problems in proteostasis are central to disease progression. Proteostasis is the synthesis and degradation of proteins. There is little evidence for abnormal protein synthesis in sporadic neurodegenerative disease. The two major systems of protein degradation in the cell are the ubiquitin proteasome system and autophagy. Both systems are controlled by protein ubiquitylation. The diseases are characterized by the accumulation of ubiquitylated protein aggregates, implying that the ubiquitin proteasome system or autophagy is malfunctioning or overwhelmed. Kinase-and ubiquitin-dependent systems exist to detect abnormal proteins in the cell. A full characterization of these enzymes in the recognition and disposal of abnormal proteins will lead to a fuller understanding of the diseases and to the development of novel therapeutic interventions. © 2011 International Society of Neuropathology.

Neurodegenerative diseases are common. Establishing a precise post-mortem diagnosis of one of these disorders is necessary to accurately attribute the cause of death, to determine familial risk and to inform clinicopathological correlation. However, to the non-specialist this may appear to be a daunting prospect. In this article we provide an overview of the clinical and neuropathological features of common neurodegenerative diseases and suggest an approach to the post-mortem examination when a neurodegenerative disease is suspected. We conclude by outlining the vital role that brain banks have in furthering our understanding of these diseases.

Ependymoma is the second most common posterior fossa tumour in children and causes significant neurological morbidity and mortality. Although these tumours are morphologically similar, recent advances in genomics have revealed that posterior fossa ependymoma (PF-EPN) is actually comprised of three distinct biological entities. Despite these differences, PF-EPN commonly resists chemotherapy and majority of them will recur. Recurrent ependymoma is fatal in children, and yet little is known about its biology. We hypothesized that post-transcriptional changes such as alternative splicing could reveal the underlying mechanisms and uncover genes that would inform actionable targets for therapy. To this end, we mapped the alternative splicing landscape in 17 matched paired samples of primary-recurrent PF-EPNs in children using RNA-seq. We identified 582 differential alternative splicing (AS) events between primary and recurrent PF-EPN, covering five basic types of AS patterns with cassette exon skipping being the majority of the AS events affected (~ 63%). These AS events were enriched for cancer hallmarks important for sustained proliferation and invasion, and affecting key regulators of invasive phenotype such as CD44 and TNC. In addition, immune system genes were enriched among AS events that show shift in inclusion levels in recurrent PF-EPN. Strikingly, genes with AS events did not show significant expression changes between primary and recurrent PF-EPN at the whole-transcript level, suggesting, AS events are an independent and informative measure for defining recurrent ependymoma. Collectively, our data provides evidence for widespread splicing dysregulation in PF-EPN, and suggests the role of aberrant AS in the pathogenesis of ependymoma.

Ependymoma is the second most common malignant brain tumour in children. Relapse occurs in approximately 50% cases and is associated with a very poor prognosis. Recent studies highlighted the importance of DNA methylation in ependymoma. However, less is understood of its role at relapse. DNA methylation profiles were generated for 146 primary and 118 recurrent ependymoma samples using the Infinium HumanMethylation450 BeadChip arrays (Illumina). Samples were classified into previously defined subgroups with only 9 (6%) primary samples assigned to non-ependymoma groups. There was no significant difference in relapse risk between EPN_PFA and EPN_RELA cases. However, EPN_RELA cases relapsed significantly quicker. There was also no significant difference in survival between EPN_PFA and EPN_RELA relapsed cases. Radiotherapy given at relapse was associated with a significant improvement in survival for EPN_PFA cases but not EPN_RELA cases, although the number of cases investigated was low, limiting statistical power. The number of cases available for other ependymoma subgroups was too low for statistical analysis. However, in line with previous publications, EPN_PFB and EPN_SPINE cases displayed low relapse rates compared to other subgroups. 55 primary and matched relapsed cases were profiled. 53/55 (96%) cases, remained in the same subgroup at first relapse. Statistical comparisons suggested a low level of significant alterations in methylation levels at specific genes between primary and matched recurrent samples. In conclusion, relapse rates were very similar between common paediatric molecular subgroups and prognosis for relapsed cases was poor for all cases. Subgroups remained stable at relapse with little change in methylation levels.

The major human neurodegenerative diseases are characterised by ubiquitin-positive intraneuronal inclusions, however the precise nature of the ubiquitin modifications in these structures is unclear. Using a monoclonal antibody specific for Lys63-linked polyubiquitin we have performed the first immunohistochemical analysis of linkage-specific ubiquitination in vivo associated with neurodegeneration. Immunoreactivity was detected within the pathological lesions of Alzheimer's, Huntington's and Parkinson's disease brains, although staining of Lewy bodies in the substantia nigra in Parkinson's disease was rare, indicating a selective involvement of Lys63-linked polyubiquitin in inclusion biogenesis in this disorder. Immunoreactivity was also a feature in neurons of proteasome-depleted mice, suggesting a proteasomal contribution to the degradation of Lys63-linked polyubiquitinated proteins in vivo.

In the past twenty years, evidence has accumulated to show that ubiquitinated proteins are a consistent feature of the intraneuronal protein aggregates (inclusions) that characterize chronic neurodegenerative disease. These findings may indicate that age-related dysfunction of the 26S proteasome may be central to disease pathogenesis. The aggregate-prone proteins can also be eliminated by autophagy. We have used the Cre-recombinase/loxP genetic approach to ablate the proteasomal Psmc1 ATPase gene and deplete 26S proteasomes in neurons in different regions of the brain to mimic neurodegeneration. Deletion of the gene in dopaminergic neurons in the substantia nigra generates a new model of Parkinson disease. Ablation of the gene in the forebrain creates the first model of dementia with Lewy bodies. In both neuroanatomical regions, gene ablation causes the formation of Lewy-like inclusions together with extensive neurodegeneration. There is some evidence for neuronal autophagy in areas adjacent to inclusions. The models indicate that neuronal loss in neurodegenerative diseases can be attributed to proteasomal malfunction accompanied by Lewy-like inclusions as seen in dementia with Lewy bodies and Parkinson disease.

Neuropathological investigations have identified major hallmarks of chronic neurodegenerative disease. These include protein aggregates called Lewy bodies in dementia with Lewy bodies and Parkinson's disease. Mutations in the α-synuclein gene have been found in familial disease and this has led to intense focused research in vitro and in transgenic animals to mimic and understand Parkinson's disease. A decade of transgenesis has lead to overexpression of wild type and mutated α-synuclein, but without faithful reproduction of human neuropathology and movement disorder. In particular, widespread regional neuronal cell death in the substantia nigra associated with human disease has not been described. The intraneuronal protein aggregates (inclusions) in all of the human chronic neurodegenerative diseases contain ubiquitylated proteins. There could be several reasons for the accumulation of ubiquitylated proteins, including malfunction of the ubiquitin proteasome system (UPS). This hypothesis has been genetically tested in mice by conditional deletion of a proteasomal regulatory ATPase gene. The consequences of gene ablation in the forebrain include extensive neuronal death and the production of Lewy-like bodies containing ubiquitylated proteins as in dementia with Lewy bodies. Gene deletion in catecholaminergic neurons, including in the substantia nigra, recapitulates the neuropathology of Parkinson's disease.

An 18-month-old boy developed encephalopathy, for which extensive investigation failed to identify an etiology, 6 weeks after stem cell transplant. To exclude a potential infectious cause, we performed high-throughput RNA sequencing on brain biopsy.RNA-Seq was performed on an Illumina Miseq, generating 20 million paired-end reads. Nonhost data were checked for similarity to known organisms using BLASTx. The full viral genome was sequenced by primer walking.We identified an astrovirus, HAstV-VA1/HMO-C-UK1(a), which was highly divergent from human astrovirus (HAstV 1-8) genotypes, but closely related to VA1/HMO-C astroviruses, including one recovered from a case of fatal encephalitis in an immunosuppressed child. The virus was detected in stool and serum, with highest levels in brain and cerebrospinal fluid (CSF). Immunohistochemistry of the brain biopsy showed positive neuronal staining. A survey of 680 stool and 349 CSF samples identified a related virus in the stool of another immunosuppressed child.The discovery of HAstV-VA1/HMO-C-UK1(a) as the cause of encephalitis in this case provides further evidence that VA1/HMO-C viruses, unlike HAstV 1-8, are neuropathic, particularly in immunocompromised patients, and should be considered in the differential diagnosis of encephalopathy. With a turnaround from sample receipt to result of1 week, we confirm that RNA-Seq presents a valuable diagnostic tool in unexplained encephalitis.

Published reports of brain weight in sudden infant death syndrome (SIDS) are contradictory, although several have concluded that brain weight is increased in SIDS compared with controls or reference data. This is important as, if brain weight is significantly different, it may be of diagnostic use or provide insights into the aetiology of SIDS. The aim of this study was to use a large series of well-characterized sudden unexpected infant deaths from a single centre to provide definitive data regarding this issue.A retrospective review identified 1100 infants who had died suddenly and undergone a comprehensive autopsy at Great Ormond Street Hospital between 1996 and 2011. They were split into two groups: those in whom death could be explained and those whose deaths remained unexplained despite full investigation (SIDS/unexplained sudden unexpected death in infancy).There were 1100 cases of whom 573 (52%) were unexplained and 527 (48%) explained. Multiple regression analysis, which adjusted for sex, age and post-mortem interval, showed no difference in the ratio of brain weight : body weight between those infants dying of explained causes and those in whom no cause could be found. This finding remained true when restricting analysis to those with macroscopically normal brains.In this large series of infants dying of both explained and unexplained causes, brain weight, once corrected for body weight, did not vary consistently with the cause of death. Brain weight cannot be used as a diagnostic indicator of the cause of death or to inform hypothetical models of the pathogenesis of SIDS.

Background The functional diffusion map (fDM) has been suggested as a tool for early detection of tumor treatment efficacy. We aim to study 3 factors that could act as potential confounders in the fDM: areas of necrosis, tumor grade, and change in tumor size. Methods Thirty-four pediatric patients with brain tumors were enrolled in a retrospective study, approved by the local ethics committee, to examine the fDM. Tumors were selected to encompass a range of types and grades. A qualitative analysis was carried out to compare how fDM findings may be affected by each of the 3 confounders by comparing fDM findings to clinical image reports. Results Results show that the fDM in areas of necrosis do not discriminate between treatment response and tumor progression. Furthermore, tumor grade alters the behavior of the fDM: a decrease in apparent diffusion coefficient (ADC) is a sign of tumor progression in high-grade tumors and treatment response in low-grade tumors. Our results also suggest using only tumor area overlap between the 2 time points analyzed for the fDM in tumors of varying size. Conclusions Interpretation of fDM results needs to take into account the underlying biology of both tumor and healthy tissue. Careful interpretation of the results is required with due consideration to areas of necrosis, tumor grade, and change in tumor size.

Focal cortical dysplasia (FCD) is a localized malformation of cortical development and is the commonest cause of severe childhood epilepsy in surgical practice. Children with FCD are severely disabled by their epilepsy, presenting with frequent seizures early in life. The commonest form of FCD in children is characterized by the presence of an abnormal population of cells, known as balloon cells. Similar pathological changes are seen in the cortical malformations that characterize patients with tuberous sclerosis complex (TSC). However, the cellular and molecular mechanisms that underlie the malformations of FCD and TSC are not well understood. We provide evidence for a defect in autophagy in FCD and TSC. We have found that balloon cells contain vacuoles that include components of the autophagy pathway. Specifically, we show that balloon cells contain prominent lysosomes by electron microscopy, immunohistochemistry for LAMP1 and LAMP2, LysoTracker labelling and enzyme histochemistry for acid phosphatase. Furthermore, we found that balloon cells contain components of the ATG pathway and that there is cytoplasmic accumulation of the regulator of autophagy, DOR. Most importantly we found that there is abnormal accumulation of the autophagy cargo protein, p62. We show that this defect in autophagy can be, in part, reversed in vitro by inhibition of the mammalian target of rapamycin (mTOR) suggesting that abnormal activation of mTOR may contribute directly to a defect in autophagy in FCD and TSC.

Aims Abnormalities of the hippocampus are associated with a range of diseases in children, including epilepsy and sudden death. A population of rod cells in part of the hippocampus, the polymorphic layer of the dentate gyrus, has long been recognized in infants. Previous work suggested that these cells were microglia and that their presence was associated with chronic illness and sudden infant death syndrome. Prompted by the observations that a sensitive immunohistochemical marker of microglia used in diagnostic practice does not typically stain these cells and that the hippocampus is a site of postnatal neurogenesis, we hypothesized that this transient population of cells were not microglia but neural progenitors. Methods Using archived post mortem tissue, we applied a broad panel of antibodies to establish the immunophenotype of these cells in 40 infants dying suddenly of causes that were either explained or remained unexplained, following post mortem investigation. Results The rod cells were consistently negative for the microglial markers CD45, CD68 and HLA-DR. The cells were positive, in varying proportions, for the neural progenitor marker, doublecortin, the neural stem cell marker, nestin and the neural marker, TUJ1. Conclusions These data support our hypothesis that the rod cells of the polymorphic layer of the dentate gyrus in the infant hippocampus are not microglia but a population of neural progenitors. These findings advance our understanding of postnatal neurogenesis in the human hippocampus in health and disease and are of diagnostic importance, allowing reactive microglia to be distinguished from the normal population of neural progenitors.

Infantile-onset X-linked spinal muscular atrophy ( SMAX2 ) is a rare lethal disorder linked to mutations in the UBA1 (previously UBE1 ) gene, encoding ubiquitin-activating enzyme 1 that has an important role in the ubiquitin–proteasome pathway. Published pathological reports are scarce. Here we report a male infant who presented from birth with predominantly truncal hypotonia following an antenatal history of reduced fetal movements. He had a myopathic face, profound weakness, multiple contractures and areflexia. Creatine kinase was moderately raised. Brain MRI showed non-specific symmetrical periventricular white matter changes. Neurophysiology revealed evidence of motor and sensory involvement and muscle biopsy showed marked inflammatory changes with subtle features suggestive of acute denervation. UBA1 sequencing revealed a novel hemizygous missense mutation (c.1670A>T; p.Glu557Val). He died from progressive respiratory failure at 4months. On post mortem assessment, in addition to severe ventral motor neuron pathology, there was widespread involvement of the sensory system, as well as developmental and degenerative cerebellar abnormalities. In contrast to typical SMN1 -associated SMA, the thalamus was unaffected. These findings indicate that SMAX2 is more accurately classified as a motor sensory neuronopathy rather than a pure anterior horn cell disorder. Ubiquitin–proteasome pathway defects may not only cause neurodegeneration but also affect normal neuronal development.

Chronic neurodegenerative disease is characterized by extensive regional loss of neurons in the brain and neuropathological hallmarks in surviving neurones. Genetic modelling by overexpression of hallmark proteins does not produce extensive neurodegeneration, whereas genetic deletion of neuronal 26S proteasomes does, as well as some hallmarks of human disease. Abbreviations: Aβ, amyloid β-peptide; AD, Alzheimer's disease; APP, amyloid precursor protein; TDP43, TAR DNA-binding protein 43

The significance of the accumulation of ubiquitin-positive intraneuronal inclusions in the brains of those affected with different neurodegenerative diseases is currently unclear. While one interpretation is that the disease mechanism(s) involves dysfunction of an ubiquitin-mediated process, such as the ubiquitin-proteasome system, the inclusions are also found in surviving neurones, suggesting a possible neuroprotective role. Here we review recent evidence in support of these seemingly opposing notions gleaned from cell and animal models as well as investigations of patient samples, with particular emphasis on studies relevant to Parkinson's disease.

Objective To report the clinical and radiologic features in a patient with myelofibrosis who developed atypical progressive multifocal leukoencephalopathy. Design Case report. Setting Tertiary referral center. Patient A 72-year-old man with myelofibrosis and mild leukopenia experienced progressive limb weakness and dysarthria. Results Imaging revealed almost complete sparing of the white matter with isolated involvement of the brainstem and deep gray matter. Postmortem examination led to definitive diagnosis of progressive multifocal leukoencephalopathy and demonstrated an unusual miliary pattern of disease rather than the typical confluent involvement. Genetic analysis revealed a mutation in the transcription control region of the JC polyomavirus, prompting speculation about the pathogenesis of progressive multifocal leukoencephalopathy. Conclusions Leukopenia may render patients effectively immunosuppressed. The differential diagnosis should include progressive multifocal leukoencephalopathy even in patients with atypical clinical and radiologic features.

Ubiquitin-positive intraneuronal inclusions are a consistent feature of the major human neurodegenerative diseases, suggesting that dysfunction of the ubiquitin proteasome system is central to disease etiology. Research using inhibitors of the 20S proteasome to model Parkinson's disease is controversial. We report for the first time that specifically 26S proteasomal dysfunction is sufficient to trigger neurodegenerative disease. Here, we describe novel conditional genetic mouse models using the Cre/loxP system to spatially restrict inactivation ofPsmc1(Rpt2/S4) to neurons of either the substantia nigra or forebrain (e.g., cortex, hippocampus, and striatum). PSMC1 is an essential subunit of the 26S proteasome andPsmc1conditional knock-out mice display 26S proteasome depletion in targeted neurons, in which the 20S proteasome is not affected. Impairment of specifically ubiquitin-mediated protein degradation caused intraneuronal Lewy-like inclusions and extensive neurodegeneration in the nigrostriatal pathway and forebrain regions. Ubiquitin and α-synuclein neuropathology was evident, similar to human Lewy bodies, but interestingly, inclusion bodies contained mitochondria. We support this observation by demonstrating mitochondria in an early form of Lewy body (pale body) from Parkinson's disease patients. The results directly confirm that 26S dysfunction in neurons is involved in the pathology of neurodegenerative disease. The model demonstrates that 26S proteasomes are necessary for normal neuronal homeostasis and that 20S proteasome activity is insufficient for neuronal survival. Finally, we are providing the first reproducible genetic platform for identifying new therapeutic targets to slow or prevent neurodegeneration.

Juvenile Dermatomyositis (JDM) is a rare life threatening disease affecting children. Symptoms include severe proximal muscle weakness and characteristic skin rashes. Vascular pathology is often a key finding in JDM including typical features of capillary drop out and abnormal blood vessel endothelial cells. We have observed that another common finding in JDM biopsies is the presence of tubuloreticular inclusions (TRI) detected by electron microscopy (EM) in blood vessel endothelial cells in muscle and the overlying skin. These are tubule-like structures within cisternae of endoplasmic reticulum.

Parkinson's disease (PD) is characterized by the progressive degeneration of substantia nigra pars compacta (SNpc) dopaminergic neurones and the formation of Lewy bodies (LB) in a proportion of the remaining neurones. α-synuclein is the main component of LB, but the pathological mechanisms that lead to neurodegeneration associated with LB formation remain unclear. Three pivotal elements have emerged in the development of PD: α-synuclein, mitochondria and protein degradation systems. We previously reported a unique model, created by conditional genetic depletion of 26S proteasomes in the SNpc of mice, which mechanistically links these three elements with the neuropathology of PD: progressive neurodegeneration and intraneuronal inclusion formation. Using this model, we tested the hypothesis that α-synuclein was essential for the formation of inclusions and neurodegeneration caused by 26S proteasomal depletion. We found that both of these processes were independent of α-synuclein. This provides an important insight into the relationship between the proteasome, α-synuclein, inclusion formation and neurodegeneration. We also show that the autophagy-lysosomal pathway is not activated in 26S proteasome-depleted neurones. This leads us to suggest that the paranuclear accumulation of mitochondria in inclusions in our model may reflect a role for the ubiquitin proteasome system in mitochondrial homeostasis and that neurodegeneration may be mediated through mitochondrial factors linked to inclusion biogenesis.