Assessment and rehabilitation of cognitive deficit in a Niemann-Pick type C disease patient

Niemann-Pick type C (NP-C) disease is a lipid storage disorder characterized by visceral (hepatosplenomegaly) and neurological symptoms: ataxia, dystonia, cognitive disorder, psychiatric disorder, and vertical supranuclear gaze palsy. Cognitive impairment is one of the core symptoms of NP-C disease, but there are few data about the cognitive rehabilitation treatment in NP-C patients. This case report aims to evaluate the effects of the cognitive rehabilitation treatment of a young woman affected by NP-C. Cognitive rehabilitation was performed with pc-based and paper and pencil exercises. We used a clinical approach that includes psychotherapy-based diagnostic and rehabilitation procedures and neuropsychological methods, using strategies to improve cognitive residual abilities. Our data showed an improvement of cognitive functions and quality of life after an intensive rehabilitation program.

Biosynthesis and signalling functions of central and peripheral nervous system neurosteroids in health and disease

Neurosteroids are steroid hormones synthesised de novo in the brain and peripheral nervous tissues. In contrast to adrenal steroid hormones that act on intracellular nuclear receptors, neurosteroids directly modulate plasma membrane ion channels and regulate intracellular signalling. This review provides an overview of the work that led to the discovery of neurosteroids, our current understanding of their intracellular biosynthetic machinery, and their roles in regulating the development and function of nervous tissue. Neurosteroids mediate signalling in the brain via multiple mechanisms. Here, we describe in detail their effects on GABA (inhibitory) and NMDA (excitatory) receptors, two signalling pathways of opposing function. Furthermore, emerging evidence points to altered neurosteroid function and signalling in neurological disease. This review focuses on neurodegenerative diseases associated with altered neurosteroid metabolism, mainly Niemann-Pick type C, multiple sclerosis and Alzheimer disease. Finally, we summarise the use of natural and synthetic neurosteroids as current and emerging therapeutics alongside their potential use as disease biomarkers.

Pharmacokinetics and distribution of 2-hydroxypropyl-β-cyclodextrin following a single intrathecal dose to cats

2-Hydroxypropyl-β-cyclodextrin (HP-β-CD) is an experimental therapy for Niemann-Pick disease type C (NPC) that reduced neuronal cholesterol and ganglioside storage, reduced Purkinje cell death, and increased lifespan in npc1-/- mice and NPC1 cats. In this study, tissue distribution was investigated in normal cats that received a single 120-mg dose of [¹⁴ C]-HP-β-CD (approximately 200 μCi/cat) via the cerebellomedullary cistern (CBMC) and lumbar cistern. One cat was euthanized at each of various time points up to 24 hours postdose for subsequent processing and quantitative whole-body autoradiographic analysis. HP-β-CD-derived radioactivity absorbed from the CBMC was widely distributed to cat tissues; most tissues were observed to have reached their highest concentration at 1 hour postdose. HP-β-CD-derived radioactivity penetrated into the deeper parts of the central nervous system with the highest concentration at 4 hours (403 μg Eq/g or 0.28 mM) and remained high (49.7 μg Eq/g or 0.03 mM) at 24 hours. The relatively long half-life (11-30 hours) in cerebral ventricles and the subarachnoid space surrounding the brain and spinal cord might contribute to the efficacy of HP-β-CD in NPC1 cats. Other tissues with high concentrations of radioactivity were nasal turbinates, pituitary gland, and urinary bladder, while relatively low concentrations were observed in blood and bile.

Role of Niemann-Pick Type C Disease Mutations in Dementia

BACKGROUND

Several neurological and systemic diseases can cause dementia, beyond Alzheimer's disease. Rare genetic causes are often responsible for dementia with atypical features. Recently, mutations causative for Niemann-Pick type C disease (NPC) have also been implicated in neurodegenerative diseases. NPC is an autosomal recessive lipid storage disorder caused by mutations in NPC1 and NPC2 genes. In adults, clinical presentation mimicking other neurodegenerative diseases makes diagnosis difficult. Recent evidence suggests that heterozygous mutations in NPC genes may take on etiological significance.

OBJECTIVE

To investigate the presence of NPC1 and NPC2 mutations in adults affected by neurodegenerative dementia plus.

METHODS

We performed a genetic screening on 50 patients using a wide clinical and biochemical approach to characterize the phenotype of mutated patients.

RESULTS

Sequencing analysis revealed four different and known heterozygous mutations in NPC1 and NPC2 genes. Patient 1 carried the p. F284LfsX26 in NPC1 and was affected by progressive supranuclear palsy-like syndrome. The remaining three patients showed a corticobasal syndrome and harbored the c.441+1G>A variant of NPC2 (patient 2), the missense p.N222 S mutation associated with the c.1947+8G>C variant in the splice region of intron 12 in NPC1 (patient 3), and the p.V30M mutation in NPC2 (patient 4), respectively. Filipin staining was abnormal in patients 1 and 2. mRNA analysis revealed an altered splicing of the NPC2 gene in patient 2.

CONCLUSIONS

Heterozygous mutations of NPC1 and NPC2 genes could contribute to dementia plus, at least in a subset of patients. We highlight the occurrence of NPC1 and NPC2 heterozygous variants in dementia-plus as pathological event.

The erythrocyte osmotic resistance test as screening tool for cholesterol-related lysosomal storage diseases

BACKGROUND

Erythrocyte volume regulation and membrane elasticity are essential for adaptation to osmotic and mechanical stress, and life span. Here, we evaluated whether defective cholesterol trafficking caused by the rare lysosomal storages diseases (LSDs), Niemann-Pick type C (NPC) and Lysosomal acid lipase (LAL) deficiency (LALD) impairs these properties. Moreover, we tested whether measurements of cholesterol membrane content and osmotic resistance serve as a screening test for these LSDs.

METHODS

Patients were genotyped for mutations in NPC1, NPC2, or LIPA genes. We measured LSD plasma biomarkers and LAL activity. Red blood cells (RBC) membrane cholesterol content was evaluated in 73 subjects. Osmotic resistance tests (ORT) were conducted in 121 blood samples from LSD suspected patients and controls.

RESULTS

We did not find statistically significant differences between RBC cholesterol content between subjects and controls. However, the ORT, particularly at 0.49% (w/v) hypotonic sodium chloride solution, revealed a significant higher osmotic resistance in LSDs patients than in controls. We established a cut-off value of ≤51% of haemolysis with sensibility and specificity values of 80% and 70%, respectively.

CONCLUSIONS

NPC and LALD do not alter cholesterol content in the RBC membrane but increase osmotic resistance. Therefore, ORT serves as screening test for the studied LSDs.

Quantitative Measurement of Cholesterol in Cell Populations Using Flow Cytometry and Fluorescent Perfringolysin O

Methods to quantify intracellular cholesterol are valuable for the study of its trafficking and storage in normal cells and in lysosomal storage disorders. Traditionally, cholesterol has been tracked using the small molecule, filipin. Filipin can be difficult to visualize and visualization can be cytotoxic as it requires UV illumination. Here we describe a method to measure cholesterol using a fluorescently labeled, mutant form of Perfringolysin O, a soluble protein toxin that binds cholesterol specifically. This approach has been used to measure the impact of NPC1 deficiency on lysosomal cholesterol levels and monitor the rescue of cholesterol export under conditions that reduce the thickness of the lysosomal glycocalyx.

Facial Dystonia with Facial Grimacing and Vertical Gaze Palsy with "Round the Houses" Sign in a 29-Year-Old Woman

A 29-year-old woman developed progressive dysarthria and coordination problems from the age of 15. Examination showed dysarthria, facial dystonia, bibrachial dystonia, hyperreflexia, ataxia, and emotional incontinence. Downward supranuclear gaze palsy was prominent with a "Round the Houses" sign. Magnetic resonance imaging of the brain and medulla, electroneurography, and cerebrospinal fluid were normal. A computed tomography scan showed hepatosplenomegaly. This combination of progressive neurological symptoms together with hepatosplenomegaly was suggestive of inborn error of metabolism. A bone marrow biopsy showed an increased number of macrophages with foamy content, highly suggestive of lysosomal disease. Plasmatic chitotriosidase activity and CCL18 were increased. Genetic testing showed heterozygosis for the variation c.1070C→T (p.Ser357Leu) and c.1843→T (Arg615Cys), confirming the diagnosis of Niemann-Pick type C (NPC). The "Round the Houses" sign has only been described in patients with progressive supranuclear palsy (PSP). This sign is described as an inability to produce pure vertical saccades along the midline and instead moving the eyes in a lateral arc to accomplish the movement. The observation of this sign in a patient with NPC indicates that this bedside finding is not specific for PSP, but a sign of medial longitudinal fasciculus dysfunction. The presence of facial dystonia with facial grimacing together with supranuclear gaze palsy is highly characteristic and useful for the diagnosis of NPC. NPC is an important underdiagnosed condition, given the availability of treatment and a mean diagnostic delay of 6 years.

Rapid Diagnosis of 83 Patients with Niemann Pick Type C Disease and Related Cholesterol Transport Disorders by Cholestantriol Screening

Niemann Pick type C (NP-C) is a rare neurodegenerative disorder caused by an impairment of intracellular lipid transport. Due to the heterogeneous clinical phenotype and the lack of a reliable blood test, diagnosis and therapy are often delayed for years. In the cell, accumulating cholesterol leads to increased formation of oxysterols that can be used as a powerful screening parameter for NP-C. In a large scale study, we evaluated the oxysterol cholestane-3β,5α,6β-triol (c-triol) as potential biomarker for a rapid diagnosis of NP-C. Using GC/MS, c-triol has been analyzed in 1902 plasma samples of patients with the suspicion for NP-C. Diagnosis in patients with elevated oxysterols was confirmed by genetic analysis. 71 new NP-C patients (69 NP-C1 and two NP-C2) and 12 Niemann Pick type A/B patients were identified. 24 new mutations in NPC1, one new mutation in NPC2 and three new mutations in the SMPD1 gene were found. Cholestane-3β,5α,6β-triol was elevated in Niemann Pick type C1, type C2, type A/B and in CESD disease. No other study has ever identified so many NP-C patients, proving that c-triol is a rapid and reliable biomarker to detect patients with NP-C disease and related cholesterol transport disorders. It should replace the filipin test as the first-line diagnostic assay.

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Improved diagnostics of Niemann Pick type C disease using a cholesterol oxidation product (c-triol) as biomarker

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Identification of 71 Niemann Pick type C patients by a simple blood test

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Cholestantriol should replace the filipin test as first-line diagnostic assay.

Due to the heterogeneous clinical phenotype and the lack of appropriate screening biomarkers, Niemann Pick type C was assumed to be an underdiagnosed disease. The accumulation of cholesterol and oxidative stress in NP-C cells lead to an increased oxidation rate of cholesterol. As already demonstrated by Porter et al. (2010) and Jiang et al. (2011), several oxysterols are elevated in confirmed NP-C patients. A large scale study was initiated to prove the clinical use of cholestane-3β,5α,6β-triol as a screening biomarker for Niemann Pick type C disease. We were able to identify numerous NP-C-patients in 1902 samples sent in from different countries, demonstrating that with appropriate screening centers much more patients would benefit from an earlier diagnosis and therapy.

Immune dysfunction in Niemann-Pick disease type C

Lysosomal storage diseases are inherited monogenic disorders in which lysosome function is compromised. Although individually very rare, they occur at a collective frequency of approximately one in five thousand live births and usually have catastrophic consequences for health. The lysosomal storage diseases Niemann‐Pick disease type C (NPC) is caused by mutations predominantly in the lysosomal integral membrane protein NPC1 and clinically presents as a progressive neurodegenerative disorder. In this article we review data that demonstrate significant dysregulation of innate immunity in NPC, which occurs both in peripheral organs and the CNS. In particular pro‐inflammatory responses promote disease progression and anti‐inflammatory drugs provide benefit in animal models of the disease and are an attractive target for clinical intervention in this disorder.

Niemann‐Pick disease type C is a rare, devastating, inherited lysosomal storage disease with a unique cellular phenotype characterized by lysosomal accumulation of sphingosine, various glycosphingolipids and cholesterol and a reduction in lysosomal calcium. In this review we highlight the impact of the disease on innate immune activities in both the central nervous system (CNS) and peripheral tissues and discuss their contributions to pathology and the underlying mechanisms.

Steroid hormone synthesis in mitochondria

Mitochondria are essential sites for steroid hormone biosynthesis. Mitochondria in the steroidogenic cells of the adrenal, gonad, placenta and brain contain the cholesterol side-chain cleavage enzyme, P450scc, and its two electron-transfer partners, ferredoxin reductase and ferredoxin. This enzyme system converts cholesterol to pregnenolone and determines net steroidogenic capacity, so that it serves as the chronic regulator of steroidogenesis. Several other steroidogenic enzymes, including 3β-hydroxysteroid dehydrogenase, 11β-hydroxylase and aldosterone synthase also reside in mitochondria. Similarly, the mitochondria of renal tubular cells contain two key enzymes participating in the activation and degradation of vitamin D. The access of cholesterol to the mitochondria is regulated by the steroidogenic acute regulatory protein, StAR, serving as the acute regulator of steroidogenesis. StAR action requires a complex multi-component molecular machine on the outer mitochondrial membrane (OMM). Components of this machine include the 18 kDa translocator protein (TSPO), the voltage-dependent anion chanel (VDAC-1), TSPO-associated protein 7 (PAP7, ACBD3), and protein kinase A regulatory subunit 1α (PKAR1A). The precise fashion in which these proteins interact and move cholesterol from the OMM to P450scc, and the means by which cholesterol is loaded into the OMM, remain unclear. Human deficiency diseases have been described for StAR and for all the mitochondrial steroidogenic enzymes, but not for the electron transfer proteins or for the components of the cholesterol import machine.