sabato 30 gennaio 2016
CYP46A1, the rate-limiting enzyme for cholesterol degradation, is neuroprotective in Huntington’s disease
Huntington’s disease is an autosomal dominant neurodegenerative disease caused by abnormal polyglutamine expansion in huntingtin (Exp-HTT) leading to degeneration of striatal neurons. Altered brain cholesterol homeostasis has been implicated in Huntington’s disease, with increased accumulation of cholesterol in striatal neurons yet reduced levels of cholesterol metabolic precursors. To elucidate these two seemingly opposing dysregulations, we investigated the expression of cholesterol 24-hydroxylase (CYP46A1), the neuronal-specific and rate-limiting enzyme for cholesterol conversion to 24S-hydroxycholesterol (24S-OHC). CYP46A1 protein levels were decreased in the putamen, but not cerebral cortex samples, of post-mortem Huntington’s disease patients when compared to controls. mRNA and CYP46A1 protein levels were also decreased in the striatum of the R6/2 Huntington’s disease mouse model and in STQ111 cell lines. , in a wild-type context, knocking down CYP46A1 expression in the striatum, via an adeno-associated virus-mediated delivery of selective shCYP46A1, reproduced the Huntington’s disease phenotype, with spontaneous striatal neuron degeneration and motor deficits, as assessed by rotarod. , CYP46A1 restoration protected STQ111 and Exp-HTT-expressing striatal neurons in culture from cell death. In the R6/2 Huntington’s disease mouse model, adeno-associated virus-mediated delivery of CYP46A1 into the striatum decreased neuronal atrophy, decreased the number, intensity level and size of Exp-HTT aggregates and improved motor deficits, as assessed by rotarod and clasping behavioural tests. Adeno-associated virus-CYP46A1 infection in R6/2 mice also restored levels of cholesterol and lanosterol and increased levels of desmosterol. , lanosterol and desmosterol were found to protect striatal neurons expressing Exp-HTT from death. We conclude that restoring CYP46A1 activity in the striatum promises a new therapeutic approach in Huntington’s disease.
This study focused on the molecular characterization of patients with leukoencephalopathy associated with a specific biochemical defect of mitochondrial respiratory chain complex III, and explores the impact of a distinct magnetic resonance imaging pattern of leukoencephalopathy to detect biallelic mutations in in patients with biochemically unclassified leukoencephalopathy. ‘Targeted resequencing’ of a custom panel including genes coding for mitochondrial proteins was performed in patients with complex III deficiency without a molecular genetic diagnosis. Based on brain magnetic resonance imaging findings in these patients, we selected additional patients from a database of unclassified leukoencephalopathies who were scanned for mutations in by Sanger sequencing. Targeted sequencing revealed homozygous mutations in , encoding mitochondrial LYR motif-containing protein 7, in four patients from three unrelated families who had a leukoencephalopathy and complex III deficiency. Two subjects harboured previously unreported variants predicted to be damaging, while two siblings carried an already reported pathogenic homozygous missense change. Sanger sequencing performed in the second cohort of patients revealed mutations in three additional patients, who were selected on the basis of the magnetic resonance imaging pattern. All patients had a consistent magnetic resonance imaging pattern of progressive signal abnormalities with multifocal small cavitations in the periventricular and deep cerebral white matter. Early motor development was delayed in half of the patients. All patients but one presented with subacute neurological deterioration in infancy or childhood, preceded by a febrile infection, and most patients had repeated episodes of subacute encephalopathy with motor regression, irritability and stupor or coma resulting in major handicap or death. LYRM7 protein was strongly reduced in available samples from patients; decreased complex III holocomplex was observed in fibroblasts from a patient carrying a splice site variant; functional studies in yeast confirmed the pathogenicity of two novel mutations. Mutations in were previously found in a single patient with a severe form of infantile onset encephalopathy. We provide new molecular, clinical, and neuroimaging data allowing us to characterize more accurately the molecular spectrum of mutations highlighting that a distinct and recognizable magnetic resonance imaging pattern is related to mutations in this gene. Inter- and intrafamilial variability exists and we observed one patient who was asymptomatic by the age of 6 years.
In patients presenting with a clinically isolated syndrome, MRI can support and substitute clinical information in the diagnosis of multiple sclerosis by showing disease dissemination in space and time and by helping to exclude disorders that can mimic multiple sclerosis. MRI criteria were first included in the diagnostic work-up for multiple sclerosis in 2001, and since then several modifications to the criteria have been proposed in an attempt to simplify lesion-count models for showing disease dissemination in space, change the timing of MRI scanning to show dissemination in time, and increase the value of spinal cord imaging. Since the last update of these criteria, new data on the use of MRI to establish dissemination in space and time have become available, and MRI technology has improved. State-of-the-art MRI findings in these patients were discussed in a MAGNIMS workshop, the goal of which was to provide an evidence-based and expert-opinion consensus on proposed modifications to MRI criteria for the diagnosis of multiple sclerosis.
Lancet Neurology 2016
Phenytoin for neuroprotection in patients with acute optic neuritis: a randomised, placebo-controlled, phase 2 trial
Acute demyelinating optic neuritis, a common feature of multiple sclerosis, can damage vision through neurodegeneration in the optic nerve and in its fibres in the retina. Inhibition of voltage-gated sodium channels is neuroprotective in preclinical models. In this study we aimed to establish whether sodium-channel inhibition with phenytoin is neuroprotective in patient with acute optic neuritis.
We did a randomised, placebo-controlled, double-blind phase 2 trial at two UK academic hospitals in London and Sheffield. Patients with acute optic neuritis aged 18–60 years, presenting within 2 weeks of onset, with visual acuity of 6/9 or worse, were randomly assigned (1:1) by minimisation via a web-based service to oral phenytoin (maintenance dose 4 mg/kg per day if randomised before or on July 16, 2013, and 6 mg/kg per day if randomised on or after July 17, 2013) or placebo for 3 months, stratified by time from onset, centre, previous multiple sclerosis diagnosis, use of disease-modifying treatment, and use of corticosteroids for acute optic neuritis. Participants and treating and assessing physicians were masked to group assignment. The primary outcome was retinal nerve fibre layer (RNFL) thickness in the affected eye at 6 months, adjusted for fellow-eye RNFL thickness at baseline, analysed in a modified intention-to-treat population of all randomised participants who were followed up at 6 months. Safety was analysed in the entire population, including those who were lost to follow-up. The trial is registered with ClinicalTrials.gov, number NCT 01451593.
We recruited 86 participants between Feb 3, 2012, and May 22, 2014 (42 assigned to phenytoin and 44 to placebo). 29 were assigned to phenytoin 4 mg/kg and 13 to phenytoin 6 mg/kg. Five participants were lost to follow-up, so the primary analysis included 81 participants (39 assigned to phenytoin and 42 to placebo). Mean 6-month RNFL thickness in the affected eye at 6 months was 81·46 μm (SD 16·27) in the phenytoin group (a mean decrease of 16·69 μm [SD 13·73] from baseline) versus 74·29 μm (15·14) in the placebo group (a mean decrease of 23·79 μm [13·97] since baseline; adjusted 6-month difference of 7·15 μm [95% CI 1·08–13·22]; p=0·021), corresponding to a 30% reduction in the extent of RNFL loss with phenytoin compared with placebo. Treatment was well tolerated, with five (12%) of 42 patients having a serious adverse event in the phenytoin group (only one, severe rash, was attributable to phenytoin) compared with two (5%) of 44 in the placebo group.
These findings support the concept of neuroprotection with phenytoin in patients with acute optic neuritis at concentrations at which it blocks voltage-gated sodium channels selectively. Further investigation in larger clinical trials in optic neuritis and in relapsing multiple sclerosis is warranted.
Amyotrophic lateral sclerosis and frontotemporal dementia: distinct and overlapping changes in eating behaviour and metabolism
Metabolic changes incorporating fluctuations in weight, insulin resistance, and cholesterol concentrations have been identified in several neurodegenerative disorders. Whether these changes result from the neurodegenerative process affecting brain regions necessary for metabolic regulation or whether they drive the degenerative process is unknown. Emerging evidence from epidemiological, clinical, pathological, and experimental studies emphasises a range of changes in eating behaviours and metabolism in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). In ALS, metabolic changes have been linked to disease progression and prognosis. Furthermore, changes in eating behaviour that affect metabolism have been incorporated into the diagnostic criteria for FTD, which has some clinical and pathological overlap with ALS. Whether the distinct and shared metabolic and eating changes represent a component of the proposed spectrum of the two diseases is an intriguing possibility. Moreover, future research should aim to unravel the complex connections between eating, metabolism, and neurodegeneration in ALS and FTD, and aim to understand the potential for targeting modifiable risk factors in disease development and progression.
Lancet Neurology 2016
Human Mutation 2016
Biallelic Truncating Mutations in TANGO2 Cause Infancy-Onset Recurrent Metabolic Crises with Encephalocardiomyopathy
Molecular diagnosis of mitochondrial disorders is challenging because of extreme clinical and genetic heterogeneity. By exome sequencing, we identified three different biallelic truncating mutations in in three unrelated individuals with infancy-onset episodic metabolic crises characterized by encephalopathy, hypoglycemia, rhabdomyolysis, arrhythmias, and laboratory findings suggestive of a defect in mitochondrial fatty acid oxidation. Over the course of the disease, all individuals developed global brain atrophy with cognitive impairment and pyramidal signs. (transport and Golgi organization 2) encodes a protein with a putative function in redistribution of Golgi membranes into the endoplasmic reticulum in and a mitochondrial localization has been confirmed in mice. Investigation of palmitate-dependent respiration in mutant fibroblasts showed evidence of a functional defect in mitochondrial β-oxidation. Our results establish TANGO2 deficiency as a clinically recognizable cause of pediatric disease with multi-organ involvement.
sabato 23 gennaio 2016
Five trials that investigated the efficacy of modern endovascular therapies for stroke — MR CLEAN, ESCAPE, SWIFT PRIME, EXTEND IA and REVASCAT — have been published within the past year, changing the landscape of acute stroke management. The trials used a variety of imaging modalities and combinations of treatment approaches, including the mandatory use of intravenous thrombolysis before the initiation of endovascular therapy. All five trials provided strong evidence to support the use of thrombectomy that is initiated within 6 h of stroke onset, prompting worldwide changes in the guidelines for management of acute stroke by endovascular treatment. The benefits of endovascular therapy were observed irrespective of a patient's age, their NIH Stroke Scale score, or whether they received intravenous thrombolysis. In this article, we review the main findings of these recent trials, focusing on key aspects of their designs, and discuss their impact on the future management of patients with acute stroke that results from large-vessel occlusion. We discuss the values of noncontrast CT ASPECTS, perfusion imaging and angiography for selecting patients to receive endovascular interventions. We also consider the role of thrombectomy beyond 6 h after stroke onset, and in patients with posterior circulation strokes.
Nature Reviews Neurology 2016
Chemokine receptors have been implicated in a wide range of CNS inflammatory diseases and have important roles in the recruitment and positioning of immune cells within tissues. Among them, the chemokine (C–C motif) receptor 5 (CCR5) can be targeted by maraviroc, a readily available and well-tolerated drug that was developed for the treatment of HIV. Correlative evidence implicates the CCR5–chemokine axis in multiple sclerosis, Rasmussen encephalitis, progressive multifocal leukoencephalopathy-associated immune reconstitution inflammatory syndrome, and infectious diseases, such as cerebral malaria and HIV-associated neurocognitive disorders. On the basis of this evidence, we postulate in this Review that CCR5 antagonists, such as maraviroc, offer neuroprotective benefits in settings in which CCR5 promotes deleterious neuroinflammation, particularly in diseases in which CD8+ T cells seem to play a pivotal role.
Nature Reviews Neurology 2016
The treatment of epileptic seizure disorders is not restricted to the achievement of seizure-freedom, but must also include the management of comorbid medical, neurological, psychiatric and cognitive comorbidities. Psychiatric and neurological comorbidities are relatively common and often co-exist in people with epilepsy (PWE). For example, depression and anxiety disorders are the most common psychiatric comorbidities in PWE, and they are particularly common in PWE who also have a neurological comorbidity, such as migraine, stroke, traumatic brain injury or dementia. Moreover, psychiatric and neurological comorbodities often have a more severe impact on the quality of life in patients with treatment-resistant focal epilepsy than do the actual seizures. Epilepsy and psychiatric and neurological comorbidities have a complex relationship, which has a direct bearing on the management of both seizures and the comorbidities: the comorbidities have to be factored into the selection of antiepileptic drugs, and the susceptibility to seizures has to be considered when choosing the drugs to treat comorbidities. The aim of this Review is to highlight the complex relationship between epilepsy and common psychiatric and neurological comorbidities, and provide an overview of how treatment strategies for epilepsy can positively and negatively affect these comorbidities and vice versa.
Nature Reviews Neurology 2016