Defective iron homeostasis and hematological abnormalities in Niemann-Pick disease type C1.

Background: Niemann-Pick disease type C1 (NPC1) is a neurodegenerative lysosomal storage disorder characterized by the accumulation of multiple lipids in the late endosome/lysosomal system and reduced acidic store calcium. The lysosomal system regulates key aspects of iron homeostasis, which prompted us to investigate whether there are hematological abnormalities and iron metabolism defects in NPC1. Methods: Iron-related hematological parameters, systemic and tissue metal ion and relevant hormonal and proteins levels, expression of specific pro-inflammatory mediators and erythrophagocytosis were evaluated in an authentic mouse model and in a large cohort of NPC patients. Results: Significant changes in mean corpuscular volume and corpuscular hemoglobin were detected in Npc1 -/- mice from an early age. Hematocrit, red cell distribution width and hemoglobin changes were observed in late-stage disease animals. Systemic iron deficiency, increased circulating hepcidin, decreased ferritin and abnormal pro-inflammatory cytokine levels were also found. Furthermore, there is evidence of defective erythrophagocytosis in Npc1 -/- mice and in an in vitro NPC1 cellular model. Comparable hematological changes, including low normal serum iron and transferrin saturation and low cerebrospinal fluid ferritin were confirmed in NPC1 patients. Conclusions: These data suggest loss of iron homeostasis and hematological abnormalities in NPC1 may contribute to the pathophysiology of this disease.

Transcriptome of HPßCD-treated Niemann-Pick disease type C1 cells highlights GPNMB as a biomarker for therapeutics.

The rare, fatal neurodegenerative disorder Niemann-Pick disease type C1 (NPC1) arises from lysosomal accumulation of unesterified cholesterol and glycosphingolipids. These subcellular pathologies lead to phenotypes of hepatosplenomegaly, neurological degeneration and premature death. The timing and severity of NPC1 clinical presentation is extremely heterogeneous. This study analyzed RNA-Seq data from 42 NPC1 patient-derived, primary fibroblast cell lines to determine transcriptional changes induced by treatment with 2-hydroxypropyl-ß-cyclodextrin (HPßCD), a compound currently under investigation in clinical trials. A total of 485 HPßCD-responsive genes were identified. Pathway enrichment analysis of these genes showed significant involvement in cholesterol and lipid biosynthesis. Furthermore, immunohistochemistry of the cerebellum as well as measurements of plasma from Npc1m1N null mice treated with HPßCD and adeno-associated virus gene therapy suggests that one of the identified genes, GPNMB, may serve as a useful biomarker of treatment response in NPC1 disease. Overall, this large NPC1 patient-derived dataset provides a comprehensive foundation for understanding the genomic response to HPßCD treatment.

Hepatocellular carcinoma as a complication of Niemann-Pick disease type C1.

Niemann-Pick disease type C (NPC) is a rare and fatal lysosomal storage disorder characterized by neurodegeneration and hepatic involvement. Mutations in either NPC1 or NPC2, two genes encoding lysosomal proteins, lead to an intracellular accumulation of unesterified cholesterol and sphingolipids in late endosomes/lysosomes. Early cholestatic disease is considered a hallmark of patients with early disease onset. This can potentially result in liver failure shortly after birth or subclinical hepatic inflammation. Previous reports suggest an association between NPC and hepatocellular carcinoma, a cancer that is rare during childhood. We present a 12-year-old male with a known diagnosis of NPC1 disease who was found to have a stage III hepatocellular carcinoma, underwent surgical resection with adjuvant chemotherapy, and subsequently died from metastatic disease. This report provides evidence of an increased risk of hepatocellular carcinoma in NPC patients, suggesting a need for screening in this patient population.

Quantitating the epigenetic transformation contributing to cholesterol homeostasis using Gaussian process.

To understand the impact of epigenetics on human misfolding disease, we apply Gaussian-process regression (GPR) based machine learning (ML) (GPR-ML) through variation spatial profiling (VSP). VSP generates population-based matrices describing the spatial covariance (SCV) relationships that link genetic diversity to fitness of the individual in response to histone deacetylases inhibitors (HDACi). Niemann-Pick C1 (NPC1) is a Mendelian disorder caused by >300 variants in the NPC1 gene that disrupt cholesterol homeostasis leading to the rapid onset and progression of neurodegenerative disease. We determine the sequence-to-function-to-structure relationships of the NPC1 polypeptide fold required for membrane trafficking and generation of a tunnel that mediates cholesterol flux in late endosomal/lysosomal (LE/Ly) compartments. HDACi treatment reveals unanticipated epigenomic plasticity in SCV relationships that restore NPC1 functionality. GPR-ML based matrices capture the epigenetic processes impacting information flow through central dogma, providing a framework for quantifying the effect of the environment on the healthspan of the individual.

Gastrointestinal Tract Pathology in a BALB/c Niemann-Pick Disease Type C1 Null Mouse Model.

BACKGROUND: Niemann-Pick disease, type C (NPC) is a rare lysosomal storage disorder characterized by progressive neurodegeneration, splenomegaly, hepatomegaly, and early death. NPC is caused by mutations in either the NPC1 or NPC2 gene. Impaired NPC function leads to defective intracellular transport of unesterified cholesterol and its accumulation in late endosomes and lysosomes. A high frequency of Crohn disease has been reported in NPC1 patients, suggesting that gastrointestinal tract pathology may become a more prominent clinical issue if effective therapies are developed to slow the neurodegeneration. The Npc1 nih mouse model on a BALB/c background replicates the hepatic and neurological disease observed in NPC1 patients. Thus, we sought to characterize the gastrointestinal tract pathology in this model to determine whether it can serve as a model of Crohn disease in NPC1. METHODS: We analyzed the gastrointestinal tract and isolated macrophages of BALB/cJ cNctr-Npc1m1N/J (Npc1-/-) mouse model to determine whether there was any Crohn-like pathology or inflammatory cell activation. We also evaluated temporal changes in the microbiota by 16S rRNA sequencing of fecal samples to determine whether there were changes consistent with Crohn disease. RESULTS: Relative to controls, Npc1 mutant mice demonstrate increased inflammation and crypt abscesses in the gastrointestinal tract; however, the observed pathological changes are significantly less than those observed in other Crohn disease mouse models. Analysis of Npc1 mutant macrophages demonstrated an increased response to lipopolysaccharides and delayed bactericidal activity; both of which are pathological features of Crohn disease. Analysis of the bacterial microbiota does not mimic what is reported in Crohn disease in either human or mouse models. We did observe significant increases in cyanobacteria and epsilon-proteobacteria. The increase in epsilon-proteobacteria may be related to altered cholesterol homeostasis since cholesterol is known to promote growth of this bacterial subgroup. CONCLUSIONS: Macrophage dysfunction in the BALB/c Npc1-/- mouse is similar to that observed in other Crohn disease models. However, neither the degree of pathology nor the microbiota changes are typical of Crohn disease. Thus, this mouse model is not a good model system for Crohn disease pathology reported in NPC1 patients.

Intrathecal 2-hydroxypropyl-ß-cyclodextrin decreases neurological disease progression in Niemann-Pick disease, type C1: a non-randomised, open-label, phase 1-2 trial.

BACKGROUND: Niemann-Pick disease, type C1 (NPC1) is a lysosomal storage disorder characterised by progressive neurodegeneration. In preclinical testing, 2-hydroxypropyl-ß-cyclodextrins (HPßCD) significantly delayed cerebellar Purkinje cell loss, slowed progression of neurological manifestations, and increased lifespan in mouse and cat models of NPC1. The aim of this study was to assess the safety and efficacy of lumbar intrathecal HPßCD. METHODS: In this open-label, dose-escalation phase 1-2a study, we gave monthly intrathecal HPßCD to participants with NPC1 with neurological manifestation at the National Institutes of Health (NIH), Bethesda, MD, USA. To explore the potential effect of 2-week dosing, three additional participants were enrolled in a parallel study at Rush University Medical Center (RUMC), Chicago, IL, USA. Participants from the NIH were non-randomly, sequentially assigned in cohorts of three to receive monthly initial intrathecal HPßCD at doses of 50, 200, 300, or 400 mg per month. A fifth cohort of two participants received initial doses of 900 mg. Participants from RUMC initially received 200 or 400 mg every 2 weeks. The dose was escalated based on tolerance or safety data from higher dose cohorts. Serum and CSF 24(S)-hydroxycholesterol (24[S]-HC), which serves as a biomarker of target engagement, and CSF protein biomarkers were evaluated. NPC Neurological Severity Scores (NNSS) were used to compare disease progression in HPßCD-treated participants relative to a historical comparison cohort of 21 NPC1 participants of similar age range. FINDINGS: Between Sept 21, 2013, and Jan 19, 2015, 32 participants with NPC1 were assessed for eligibility at the National Institutes of Health. 18 patients were excluded due to inclusion criteria not met (six patients), declined to participate (three patients), pursued independent expanded access and obtained the drug outside of the study (three patients), enrolled in the RUMC cohort (one patient), or too late for the trial enrolment (five patients). 14 patients were enrolled and sequentially assigned to receive intrathecal HPßCD at a starting dose of 50 mg per month (three patients), 200 mg per month (three patients), 300 mg per month (three patients), 400 mg per month (three patients), or 900 mg per month (two patients). During the first year, two patients had treatment interrupted for one dose, based on grade 1 ototoxicity. All 14 patients were assessed at 12 months. Between 12 and 18 months, one participant had treatment interrupted at 17 months due to hepatocellular carcinoma, one patient had dose interruption for 2 doses based on caregiver hardship and one patient had treatment interrupted for 1 dose for mastoiditis. 11 patients were assessed at 18 months. Between Dec 11, 2013, and June 25, 2014, three participants were assessed for eligibility and enrolled at RUMC, and were assigned to receive intrathecal HPßCD at a starting dose of 200 mg every 2 weeks (two patients), or 400 mg every two weeks (one patient). There were no dropouts in this group and all 3 patients were assessed at 18 months. Biomarker studies were consistent with improved neuronal cholesterol homoeostasis and decreased neuronal pathology. Post-drug plasma 24(S)-HC area under the curve (AUC8-72) values, an indicator of neuronal cholesterol homoeostasis, were significantly higher than post-saline plasma 24(S)-HC AUC8-72 after doses of 900 mg (p=0·0063) and 1200 mg (p=0·0037). CSF 24(S)-HC concentrations in three participants given either 600 or 900 mg of HPßCD were increased about two fold (p=0·0032) after drug administration. No drug-related serious adverse events were observed. Mid-frequency to high-frequency hearing loss, an expected adverse event, was documented in all participants. When managed with hearing aids, this did not have an appreciable effect on daily communication. The NNSS for the 14 participants treated monthly increased at a rate of 1·22, SEM 0·34 points per year compared with 2·92, SEM 0·27 points per year (p=0·0002) for the 21 patient comparison group. Decreased progression was observed for NNSS domains of ambulation (p=0·0622), cognition (p=0·0040) and speech (p=0·0423). INTERPRETATION: Patients with NPC1 treated with intrathecal HPßCD had slowed disease progression with an acceptable safety profile. These data support the initiation of a multinational, randomised, controlled trial of intrathecal HPßCD. FUNDING: National Institutes of Health, Dana's Angels Research Trust, Ara Parseghian Medical Research Foundation, Hope for Haley, Samantha's Search for the Cure Foundation, National Niemann-Pick Disease Foundation, Support of Accelerated Research for NPC Disease, Vtesse, Janssen Research and Development, a Johnson & Johnson company, and Johnson & Johnson.