Nitin R. Wadhwani

Differential Reliance on Autophagy for Protection from HSV Encephalitis between Newborns and Adults

Newborns are more susceptible to severe disease from infection than adults, with maturation of immune responses implicated as a major factor. The type I interferon response delays mortality and limits viral replication in adult mice in a model of herpes simplex virus (HSV) encephalitis. We found that intact type I interferon signaling did not control HSV disease in the neonatal brain. However, the multifunctional HSV protein γ34.5 involved in countering type I interferon responses was important for virulence in the brain in both age groups. To investigate this observation further, we studied a specific function of γ34.5 which contributes to HSV pathogenesis in the adult brain, inhibition of the cellular process of autophagy. Surprisingly, we found that the beclin binding domain of γ34.5 responsible for inhibiting autophagy was dispensable for HSV disease in the neonatal brain, as infection of newborns with the deletion mutant decreased time to mortality compared to the rescue virus. Additionally, a functional beclin binding domain in HSV γ34.5 did not effectively inhibit autophagy in the neonate, unlike in the adult. Type I IFN responses promote autophagy in adult, a finding we confirmed in the adult brain after HSV infection; however, in the newborn brain we observed that autophagy was activated through a type I IFN-independent mechanism. Furthermore, autophagy in the wild-type neonatal mouse was associated with increased apoptosis in infected regions of the brain. Observations in the mouse model were consistent with those in a human case of neonatal HSV encephalitis. Our findings reveal age-dependent differences in autophagy for protection from HSV encephalitis, indicating developmental differences in induction and regulation of this innate defense mechanism after HSV infection in the neonatal brain.

Thrombin decreases expression of the glutamate transporter GLAST and inhibits glutamate uptake in primary cortical astrocytes via the Rho kinase pathway

Astrocyte glutamate transporters GLAST and GLT1 play a key role in regulating neuronal excitation and their levels are altered in patients with epilepsy, and after traumatic brain injury. The mechanisms which regulate their expression are not well understood. We tested the hypothesis that exposure of astrocytes to high levels of thrombin, as may occur after a compromise of the blood-brain barrier, would reduce astrocyte glutamate transporter levels. In isolated rat cortical astrocytes we examined the effects of thrombin on the expression and function of glutamate transporters, and the signaling pathways involved in these responses by using Western blotting and selective inhibitors. Thrombin induced a selective decrease in the expression of GLAST but not GLT1, with a corresponding decrease in the capacity of astrocytes to take up glutamate. Activation of the thrombin receptor PAR-1 with an activating peptide induced a similar decrease in the expression of GLAST and compromise of glutamate uptake. The downregulation of GLAST induced by thrombin was mediated by the mitogen activated protein kinases p38 MAPK, ERK and JNK, but inhibition of these kinases did not prevent the decrease in glutamate uptake induced by thrombin. In contrast, inhibition of the Rho kinase pathway using the specific inhibitor, Y27632, suppressed both the decrease in the expression of GLAST and the decrease in glutamate uptake induced by thrombin. In hippocampal astrocyte cultures, thrombin caused a decrease in both GLAST and GLT1. In tissue resected from brains of children with intractable epilepsy, we found a decrease in the integrity of the blood-brain barrier along with a reduction in immunoreactivity for both transporters which was associated with an increase in cleaved thrombin and reactive astrogliosis. The in vitro results suggest a specific mechanism by which thrombin may lead to a compromise of astrocyte function and enhanced synaptic excitability after the blood-brain barrier is compromised. The human in vivo results provide indirect support evidence linking the compromise of the blood-brain barrier to thrombin-induced reduction in glutamate transporter expression and an increase in neuronal excitation.

Hepatobiliary cystadenoma: a rare pediatric tumor.

Hepatobiliary cystadenoma is a rare hepatic neoplasm that has been reported only 10 times in the pediatric population. Although considered a benign cystic tumor of the liver, hepatobiliary cystadenoma has a high risk of recurrence with incomplete excision and a potential risk for malignant degeneration. Complete tumor excision with negative margins is the mainstay in treatment. Unfortunately, due to the paucity of cases and its vague presentation, hepatobiliary cystadenoma is rarely diagnosed preoperatively. Therefore, in patients with hepatic cystic masses without a clear diagnosis, total resection of the lesion with negative margins is indicated to adequately evaluate for malignant potential and limit the risk of recurrence. We describe a 2-year-old girl with an asymptomatic abdominal mass that was found to be hepatobiliary cystadenoma. In addition, the pathogenic, histopathologic and clinical features of hepatobiliary cystadenoma are reviewed.

Teaching NeuroImages: Meningioangiomatosis.

A 23-month-old full-term boy presented with tonic-clonic seizures. Lumbar puncture and routine laboratory tests were unremarkable. CT (figure 1A) showed bifrontal parasagittal calcification. Brain MRI revealed corresponding signal abnormalities with gradient susceptibility (figure 1D) and enhancement (figure 1F). Differential diagnoses included prior infection, vascular malformation, and tumor. Biopsy (figure 2) was consistent with meningioangiomatosis.

Maternal to fetal transmission of cervical carcinoma

Reported cases of metastases to the placenta are uncommon, and maternal transmission of tumor to the fetus is even more infrequent. However, vertical transmission of tumor can occur and should be considered as a potential etiology of malignancy in newborns and infants born to mothers with a history of cancer during gestation. Here, we present the imaging findings and clinical course of an unusual case of maternal cervical neuroendocrine carcinoma presenting as bilateral petrous temporal bone lesions in an infant.

Alternative lengthening of telomeres, ATRX loss and H3-K27M mutations in histologically defined pilocytic astrocytoma with anaplasia: Mutations in pilocytic astrocytoma with anaplasia

Anaplasia may be identified in a subset of tumors with a presumed pilocytic astrocytoma (PA) component or piloid features, which may be associated with aggressive behavior, but the biologic basis of this change remains unclear. Fifty‐seven resections from 36 patients (23 M, 13 F, mean age 32 years, range 3–75) were included. A clinical diagnosis of NF1 was present in 8 (22%). Alternative lengthening of telomeres (ALT) was assessed by telomere‐specific FISH and/or CISH. A combination of immunohistochemistry, DNA sequencing and FISH were used to study BRAF, ATRX, CDKN2A/p16, mutant IDH1 p.R132H and H3‐K27M proteins. ALT was present in 25 (69%) cases and ATRX loss in 20 (57%), mostly in the expected association of ALT+/ATRX‐ (20/24, 83%) or ALT‐/ATRX+ (11/11, 100%). BRAF duplication was present in 8 (of 26) (31%). H3‐K27M was present in 5 of 32 (16%) cases, all with concurrent ATRX loss and ALT. ALT was also present in 9 (of 11) cases in the benign PA precursor, 7 of which also had ATRX loss in both the precursor and the anaplastic tumor. In a single pediatric case, ALT and ATRX loss developed in the anaplastic component only, and in another adult case, ALT was present in the PA‐A component only, but ATRX was not tested. Features associated with worse prognosis included subtotal resection, adult vs. pediatric, presence of a PA precursor preceding a diagnosis of anaplasia, necrosis, presence of ALT and ATRX expression loss. ALT and ATRX loss, as well as alterations involving the MAPK pathway, are frequent in PA with anaplasia at the time of development of anaplasia or in their precursors. Additionally, a small subset of PA with anaplasia have H3‐K27M mutations. These findings further support the concept that PA with anaplasia is a neoplasm with heterogeneous genetic features and alterations typical of both PA and diffuse gliomas.

Medulloblastoma with extensive nodularity (SHH medulloblastoma)

Medulloblastoma is the most common CNS embryonal tumor and the most common malignant tumor of childhood. Its overall incidence is 1.8 cases per 1 million people, with a childhood incidence of 6 cases per 1 million. 77 percent of patients are less than 19 years old. Medulloblastoma occurs in the 4th ventricle and usually presents with symptoms of increased intracranial pressure (headaches, nausea, vomiting) and signs of obstructive hydrocephalus. Medulloblastoma is both histologically and genetically defined with prognosis that depends on classification.

Targeting CD133 improves chemotherapeutic efficacy of recurrent pediatric pilocytic astrocytoma following prolonged chemotherapy

BackgroundPilocytic astrocytomas (PAs) are the most common pediatric central nervous system neoplasms. In the majority of cases these tumors are benign and receive favorable prognosis following gross total surgical resection. In patients with progressive or symptomatic tumors, aggressive surgical resection is generally not feasible, thus radiation or chemotherapy are accepted initial or adjuvant interventions. Due to serious long-lasting side-effects, radiation is limited in young children; therefore, chemotherapy is widely practiced as an adjuvant treatment for these patients. However, chemotherapy can promote the emergence of multidrug resistant tumor cells that are more malignant than those of the original tumor. CD133, a putative stem cell marker in normal tissue and malignant brain tumors, enhances multidrug resistant gene 1 (MDR1) expression following chemotherapy in adult malignant glioblastomas. This study examines the relationship between CD133 and MDR1 in pediatric PAs exposed to chemotherapy, with the goal of identifying therapeutic targets that manifest as a result of chemotherapy.MethodsSlides were obtained for 15 recurrent PAs, seven of which had received chemotherapy prior to surgical treatment for the recurrent tumor. These samples, as well as primary tumor tissue slides from the same patients were used to investigate CD133 and MDR1 expression via immunofluorescence. Archived frozen tissue samples from the same patients were used to examine CD133, MDR1 and PI3K-Akt-NF-κB signaling mediators, via western blot. Two drug resistant pediatric PA cell lines Res186 and Res199 were also used to evaluate the role of CD133 on cell response to cytotoxic therapy.ResultsCD133 and MDR1 were co-expressed and their expression was elevated in recurrent PAs from patients that had received chemotherapy, compared to patients that had not received chemotherapy. PI3K-Akt-NF-κB signaling mediator expression was also elevated in recurrent, chemotherapy-treated PA. Suppressing CD133 expression with siCD133 decreased levels of PI3K-Akt-NF-κB signaling mediators and MDR1, while increasing cell chemosensitivity, as indicated by quantification of apoptotic cells following chemotherapy.ConclusionsCD133 contributes to multidrug resistance by regulating MDR1 levels via the PI3K-Akt-NF-κB signal pathway not only in adult glioblastomas, but also in pediatric PAs. Targeting CD133, adjuvant to conventional chemotherapy may improve outcomes for children with recurrent PA.

Ameloblastic Fibroma of the Left Mandible

Ameloblastic fibroma is a rare odontogenic tumour that can occur in the paediatric population. Morphologically, it may resemble an organized proliferation of developmental remnants of the dental lamina; however it can be reliably classified as a neoplastic process by its circumscription, bland mesenchymal component, islands of epithelium, and radiographic characteristics. Our case demonstrates the classic clinical presentation for this rare odontogenic tumour and briefly discusses histologic mimics.

Abstract 2593: Accelerating pediatric brain tumor research through team science solutions

Introduction: The Children’s Brain Tumor Tissue Consortium (CBTTC), an international repository of genomic and phenotypic data, has partnered with Blackfynn, Inc., to create a cloud-based data management platform to facilitate team-science across disciplines. Background: The CBTTC through the CHOP Department of Biomedical and Health Informatics (DBHi) has developed a network of informatics and data applications for researchers across the globe to work together and perform real-time analyses on existing clinical, phenotypic, and genomic data. Historically, rare disease datasets are siloed, locked in proprietary formats, segregated by data types, and hidden from the view of experts in the field. This has been a significant barrier to finding effective therapeutics for children with pediatric brain tumors. Blackfynn was founded by a group of multidisciplinary experts in neuroscience, neurology, medicine, software development, engineering, computer science and business with the goal to empower researchers to cure neurologic disease and provide solutions to these challenges. Description of Methods: The CBTTC and Blackfynn teamed up to provide a cloud-based, team-focused data management and analytics platform. The platform provides a commercial grade, scalable approach to upload, view, and integrate digital pathology images with relevant subject data such as MRIs, pathology reports and genomic information. Stakeholders can search integrated data without requiring users to change their current workflow or conform to imposed data standards. This platform is a simple, intuitive, end-to-end software platform for teams of scientists and pathologists to review, annotate and discuss cases, enabling rapid diagnostic consensus, quality control, and empowered discovery. Summary of Unpublished Results: The CBTTC/Blackfynn data platform enabled CBTTC members to engage in a cross-institutional collaboration to reach consensus on digital pathology data in ways that were previously not possible. We demonstrated that this solution removes existing barriers to collaborative efforts and provides a rich analytic and discovery platform bridging imaging with genomics and other data formats. The platform provides a new model for the scientific community to facilitate translation towards improved treatments for children diagnosed with brain tumors. Discussion and Future Direction: This pilot project will be scaled to other CBTTC sites for centralized review of pathology images to enable the research community to collaborative on specific projects. The next phase of platform development will include further integration CBTTC platforms fully integrating genomics data, and side-by-side viewing and analyses of MRI, pathology and clincal data to facilitate specific project work around large and complex research data types in a cloud environment. Citation Format: Amanda Christini, Angela J. Waanders, Joost B. Wagenaar, Alex S. Felmeister, Mariarita Santi, Nitin R. Wadhwani, Jennifer L. Mason, Mateusz P. Koptyra, Jena V. Lilly, Jeffrey W. Pennington, Rishi R. Lulla, Adam C. Resnick. Accelerating pediatric brain tumor research through team science solutions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2593. doi:10.1158/1538-7445.AM2017-2593