Cholesterol Oxidation Products Are Sensitive and Specific Blood-Based Biomarkers for Niemann-Pick C1 Disease
03 Nov 2010-Science Translational Medicine (American Association for the Advancement of Science)-Vol. 2, Iss: 56
TL;DR: Blood concentrations of two related oxysterols molecules were almost 10 times higher in Niemann-Pick C1 patients than in age-matched healthy controls or those with other diseases such as atherosclerosis or diabetes, suggesting that the two oxysterol molecules are accurate diagnostic markers of early clinical disease and can be used not only to monitor disease progression but also to demonstrate drug efficacy.
Abstract: Niemann-Pick type C1 (NPC1) disease is a rare progressive neurodegenerative disorder characterized by accumulation of cholesterol in the endolysosomes. Previous studies implicating oxidative stress in NPC1 disease pathogenesis raised the possibility that nonenzymatic formation of cholesterol oxidation products could serve as disease biomarkers. We measured these metabolites in the plasma and tissues of the Npc1 −/− mouse model and found several cholesterol oxidation products that were elevated in Npc1 −/− mice, were detectable before the onset of symptoms, and were associated with disease progression. Nonenzymatically formed cholesterol oxidation products were similarly increased in the plasma of all human NPC1 subjects studied and delineated an oxysterol profile specific for NPC1 disease. This oxysterol profile also correlated with the age of disease onset and disease severity. We further show that the plasma oxysterol markers decreased in response to an established therapeutic intervention in the NPC1 feline model. These cholesterol oxidation products are robust blood-based biochemical markers for NPC1 disease that may prove transformative for diagnosis and treatment of this disorder, and as outcome measures to monitor response to therapy.
Citations
More filters
1,246 citations
TL;DR: The primary laboratory diagnosis requires living skin fibroblasts to demonstrate accumulation of unesterified cholesterol in perinuclear vesicles (lysosomes) after staining with filipin, and genotyping of patients is useful to confirm the diagnosis in the latter patients and essential for future prenatal diagnosis.
Abstract: Niemann-Pick C disease (NP-C) is a neurovisceral atypical lysosomal lipid storage disorder with an estimated minimal incidence of 1/120 000 live births. The broad clinical spectrum ranges from a neonatal rapidly fatal disorder to an adult-onset chronic neurodegenerative disease. The neurological involvement defines the disease severity in most patients but is typically preceded by systemic signs (cholestatic jaundice in the neonatal period or isolated spleno- or hepatosplenomegaly in infancy or childhood). The first neurological symptoms vary with age of onset: delay in developmental motor milestones (early infantile period), gait problems, falls, clumsiness, cataplexy, school problems (late infantile and juvenile period), and ataxia not unfrequently following initial psychiatric disturbances (adult form). The most characteristic sign is vertical supranuclear gaze palsy. The neurological disorder consists mainly of cerebellar ataxia, dysarthria, dysphagia, and progressive dementia. Cataplexy, seizures and dystonia are other common features. NP-C is transmitted in an autosomal recessive manner and is caused by mutations of either the NPC1 (95% of families) or the NPC2 genes. The exact functions of the NPC1 and NPC2 proteins are still unclear. NP-C is currently described as a cellular cholesterol trafficking defect but in the brain, the prominently stored lipids are gangliosides. Clinical examination should include comprehensive neurological and ophthalmological evaluations. The primary laboratory diagnosis requires living skin fibroblasts to demonstrate accumulation of unesterified cholesterol in perinuclear vesicles (lysosomes) after staining with filipin. Pronounced abnormalities are observed in about 80% of the cases, mild to moderate alterations in the remainder ("variant" biochemical phenotype). Genotyping of patients is useful to confirm the diagnosis in the latter patients and essential for future prenatal diagnosis. The differential diagnosis may include other lipidoses; idiopathic neonatal hepatitis and other causes of cholestatic icterus should be considered in neonates, and conditions with cerebellar ataxia, dystonia, cataplexy and supranuclear gaze palsy in older children and adults. Symptomatic management of patients is crucial. A first product, miglustat, has been granted marketing authorization in Europe and several other countries for specific treatment of the neurological manifestations. The prognosis largely correlates with the age at onset of the neurological manifestations.
974 citations
Cites background from "Cholesterol Oxidation Products Are ..."
...Importantly, a recent pilot study indicates that plasma of patients with NP-C show a specific oxysterol profile that could be used as a biomarker [143]....
[...]
TL;DR: Early steps in steroid biosynthesis are addressed, including how cholesterol transport to the cholesterol-poor outer mitochondrial membrane (OMM) appears to involve cholesterol transport proteins, and how chronic steroidogenic capacity is determined by CYP11A1 gene transcription.
424 citations
TL;DR: In this minireview, various MS technologies used in metabolomics are briefly discussed, and future needs are suggested.
417 citations
TL;DR: Points of consensus among experts in the diagnosis and treatment of NP-C are reported based on a follow-up meeting in Paris, France in September 2011, providing further information on detection/diagnostic methods, potential new methods of monitoring disease progression, and therapy.
395 citations
Cites background or methods from "Cholesterol Oxidation Products Are ..."
...• Plasma oxysterol levels have been shown to be related to age at neurological disease onset in NP-C animal models and patients [113,114]....
[...]
...• Pending further data on the utility of plasma oxysterol profiling, these potential new biomarkers may form useful ancillary tests to aid diagnosis in difficult cases with unclear biochemical phenotypes and NP-C gene mutations [114]....
[...]
...• Initial cross-sectional data indicate that levels of certain oxysterols correlate with disease severity as well as age at neurological disease onset in NP-C [114], but further longitudinal data are required to determine the clinical utility of these potential new markers....
[...]
...• Data on levels of cholesterol oxidation products (oxysterols) in animals and humans with NPC1 mutations have recently been reported, indicating that they are sensitive and specific markers for NP-C screening [113,114]....
[...]
...• Preliminary data indicate that plasma oxysterols profiling may be of use in monitoring disease progression over time [114], but further data are required to establish the clinical utility of oxysterols as a potential monitoring method....
[...]
References
More filters
TL;DR: Transfection of NP-C fibroblasts with wild-type NPC1 cDNA resulted in correction of their excessive lysosomal storage of LDL cholesterol, thereby defining the critical role of NPC1 in regulation of intracellular cholesterol trafficking.
Abstract: Niemann-Pick type C (NP-C) disease, a fatal neurovisceral disorder, is characterized by lysosomal accumulation of low density lipoprotein (LDL)-derived cholesterol. By positional cloning methods, a gene (NPC1) with insertion, deletion, and missense mutations has been identified in NP-C patients. Transfection of NP-C fibroblasts with wild-type NPC1 cDNA resulted in correction of their excessive lysosomal storage of LDL cholesterol, thereby defining the critical role of NPC1 in regulation of intracellular cholesterol trafficking. The 1278-amino acid NPC1 protein has sequence similarity to the morphogen receptor PATCHED and the putative sterol-sensing regions of SREBP cleavage-activating protein (SCAP) and 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase.
1,403 citations
TL;DR: A method utilizing aminopropyl bonded phase (Bond Elut) columns has been developed to separate lipid mixtures into individual classes in high yield and purity, and is superior to preparative HPLC or TLC, or other chromatographic methods for the separation of lipid mixture for subsequent analysis.
928 citations
"Cholesterol Oxidation Products Are ..." refers methods in this paper
...Oxysterol purification was accomplished using aminopropyl (Waters Sep-Pak Vac RC 500 mg NH2 Cartridges) and silica columns (Isolute 100 mg SI 10 ml XL cartridges) (59)....
[...]
TL;DR: Treatment of NP-C2 fibroblasts with exogenous recombinant HE1 protein ameliorated lysosomal accumulation of low density lipoprotein-derived cholesterol.
Abstract: Niemann-Pick type C2 disease (NP-C2) is a fatal hereditary disorder of unknown etiology characterized by defective egress of cholesterol from lysosomes. Here we show that the disease is caused by a deficiency in HE1, a ubiquitously expressed lysosomal protein identified previously as a cholesterol-binding protein. HE1 was undetectable in fibroblasts from NP-C2 patients but present in fibroblasts from unaffected controls and NP-C1 patients. Mutations in the HE1 gene, which maps to chromosome 14q24.3, were found in NP-C2 patients but not in controls. Treatment of NP-C2 fibroblasts with exogenous recombinant HE1 protein ameliorated lysosomal accumulation of low density lipoprotein-derived cholesterol.
817 citations
TL;DR: The mouse model may provide an important resource for studying the role of NPC1 in cholesterol homeostasis and neurodegeneration and for assessing the efficacy of new drugs for NP-C disease.
Abstract: An integrated human-mouse positional candidate approach was used to identify the gene responsible for the phenotypes observed in a mouse model of Niemann-Pick type C (NP-C) disease. The predicted murine NPC1 protein has sequence homology to the putative transmembrane domains of the Hedgehog signaling molecule Patched, to the cholesterol-sensing regions of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and SREBP cleavage-activating protein (SCAP), and to the NPC1 orthologs identified in human, the nematode Caenorhabditis elegans, and the yeast Saccharomyces cerevisiae. The mouse model may provide an important resource for studying the role of NPC1 in cholesterol homeostasis and neurodegeneration and for assessing the efficacy of new drugs for NP-C disease.
783 citations
"Cholesterol Oxidation Products Are ..." refers background in this paper
...To test this possibility, we monitored plasma oxysterol concentrations over the life span of the BALB/c NPC (Npc1) mouse, a naturally occurring murine model that harbors a retroposon insertion in the Npc1 gene (14)....
[...]
TL;DR: Identification of mutations revealed a complex picture of molecular heterogeneity, allowing genotype ‐ phenotype correlations for both genes and providing insights into structure ‐ function relationships for the NPC1 protein.
Abstract: Niemann-Pick disease type C (NPC) is an autosomal recessive neurovisceral lipid storage with a wide spectrum of clinical phenotypes. At the cellular level, the disorder is characterized by accumulation of unesterified cholesterol and glycolipids in the lysosomal/late endosomal system. Approximatively 95% of patients have mutations in the NPC1 gene (mapped at 18q11) which encodes a large membrane glycoprotein primarily located to late endosomes. The remainder have mutations in the NPC2 gene (mapped at 14q24.3) which encodes a small soluble lysosomal protein with cholesterol-binding properties. The identical biochemical patterns observed in NPC1 and NPC2 mutants suggest that the two proteins function in a coordinate fashion. Identification of mutations revealed a complex picture of molecular heterogeneity, allowing genotype - phenotype correlations for both genes and providing insights into structure - function relationships for the NPC1 protein. Although a whole body of evidence suggests that the NPC1 and NPC2 proteins are involved in the cellular postlysosomal/late endosomal transport of cholesterol, glycolipids and other cargo, their precise functions and relationship remain unclear and are currently the subject of intense investigation. These studies, conducted in various models, should ultimately lead to a better understanding of the pathophysiology of NPC and new therapeutic approaches.
636 citations