IntroductionPilocytic astrocytomas are slow-growing tumors that usually occur in the cerebellum or in the midline along the hypothalamic/optic pathways. The most common genetic alterations in pilocytic astrocytomas activate the ERK/MAPK signal transduction pathway, which is a major driver of proliferation but is also believed to induce senescence in these tumors. Here, we have conducted a detailed investigation of microRNA and gene expression, together with pathway analysis, to improve our understanding of the regulatory mechanisms in pilocytic astrocytomas.ResultsPilocytic astrocytomas were found to have distinctive microRNA and gene expression profiles compared to normal brain tissue and a selection of other pediatric brain tumors. Several microRNAs found to be up-regulated in pilocytic astrocytomas are predicted to target the ERK/MAPK and NF-κB signaling pathways as well as genes involved in senescence-associated inflammation and cell cycle control. Furthermore, IGFBP7 and CEBPB, which are transcriptional inducers of the senescence-associated secretory phenotype (SASP), were also up-regulated together with the markers of senescence and inflammation, CDKN1A (p21), CDKN2A (p16) and IL1B.ConclusionThese findings provide further evidence of a senescent phenotype in pilocytic astrocytomas. In addition, they suggest that the ERK/MAPK pathway, which is considered the major driver of these tumors, is regulated not only by genetic aberrations but also by microRNAs.Electronic supplementary materialThe online version of this article (doi:10.1186/s40478-015-0266-3) contains supplementary material, which is available to authorized users.

BackgroundA considerable number of people with multiple sclerosis (pwMS) live in low- and middle-income countries (LMIC), where lack of resource adversely affects access to effective disease-modifying treatment.ObjectiveThe objective of this commentary is to propose a useful cost-effective disease-modifying treatment option for pwMS in LMIC with potential high efficacy and high convenience to the pwMS and treating physician.Viewpoint: We propose using generic 2-chloro-2’-deoxyadenosine (cladribine), a small molecule licensed for treatment of people with hairy cell leukaemia, as a solution of this significant equity imbalance. Cladribine has been shown in phase II and III trials to be a highly effective disease-modifying treatment for pwMS, and its adverse effect profile is comparable with any DMT currently licensed in high-income economies where an oral preparation has recently been licensed by the European Medicines Agency.ConclusionOur viewpoint takes into account experience we have gathered over the past three years in the use of generic cladribine to treat pwMS. Whilst here we focus on MS, there is significant potential for use of cladribine in other conditions that could benefit from its mechanism of action.

Low-grade gliomas (LGGs) account for about a third of all brain tumours in children. We conducted a detailed study of DNA methylation and gene expression to improve our understanding of the biology of pilocytic and diffuse astrocytomas. Pilocytic astrocytomas were found to have a distinctive signature at 315 CpG sites, of which 312 were hypomethylated and 3 were hypermethylated. Genomic analysis revealed that 182 of these sites are within annotated enhancers. The signature was not present in diffuse astrocytomas, or in published profiles of other brain tumours and normal brain tissue. The AP-1 transcription factor was predicted to bind within 200 bp of a subset of the 315 differentially methylated CpG sites; the AP-1 factors, FOS and FOSL1 were found to be up-regulated in pilocytic astrocytomas. We also analysed splice variants of the AP-1 target gene, CCND1, which encodes cell cycle regulator cyclin D1. CCND1a was found to be highly expressed in both pilocytic and diffuse astrocytomas, but diffuse astrocytomas have far higher expression of the oncogenic variant, CCND1b. These findings highlight novel genetic and epigenetic differences between pilocytic and diffuse astrocytoma, in addition to well-described alterations involving BRAF, MYB and FGFR1.Electronic supplementary materialThe online version of this article (doi:10.1186/s40478-016-0323-6) contains supplementary material, which is available to authorized users.

An 81-year-old man presented with fever, confusion and rapidly-progressive flaccid tetraparesis. Clinical presentation and neurophysiology were consistent with a severe axonal polyneuropathy. Anti-GM1 and serology were both positive, consistent with postinfectious axonal-variant Guillain-Barré syndrome (GBS). GBS is characterised by albuminocytological dissociation, where an elevated protein and acellular cerebrospinal fluid are typical. However, in this case, CSF analysis revealed an exaggerated pleocytosis (72 white blood cells (WBC)/mm). No source of central nervous system infection or inflammation was identified despite thorough investigation. The patient was treated with intravenous immunoglobulin and intensive rehabilitation.Albuminocytological dissociation classically distinguishes GBS from infective causes of flaccid weakness (eg, enteroviruses, flaviviruses and HIV). Diagnostic criteria frequently cite a pleocytosis of <50 WBC/mm as required in the diagnosis of GBS. However, this case demonstrates that pleocytosis exceeding this level can occur in the presence of convincing evidence of GBS and without demonstrable neurotropic infection.

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