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Sphingomyelinase activity levels in human peripheral blood leukocytes, using [3H]sphingomyelin as substrate: study of heterozygotes and homozygotes for Niemann-Pick disease variants.

Patients and heterozygous carriers of Niemann-Pick disease types A and B as well as the primary (genetic) sea-blue histiocyte syndrome were investigated for their leukocyte sphingomyelinase activity. In parallel, glucocerebrosidase activity was determined in all cases studied. [3H]Sphingomyelin and [14C]glucocerebroside served as substrates for sphingomyelinase and glucocerebrosidase activity measurements, respectively. Conditions for these enzymes' assays are discussed. Sphingomyelinase activity was completely absent in three cases of Niemann-Pick disease type A and significantly diminished in one patient with Niemann-Pick disease type B and two with the sea-blue histiocyte syndrome. Sphingomyelinase activity in obligatory heterozygotes of all variants investigated represented about 40 to 70% of normal activity. Nevertheless, some overlapping with normal values occasionally occurred. Interestingly, glucocerbrosidase activity was elevated in patients with Niemann-Pick disease variants.

Glucosylceramidase↗

Elevated Cerebrospinal Fluid Total Tau in Niemann-Pick Disease Type C1: Correlation With Clinical Severity and Response to Therapeutic Interventions.

Niemann-Pick disease, type C1 (NPC1) is an inborn error of intracellular cholesterol transport. Impaired function of NPC1 leads to endolysosomal accumulation of unesterified cholesterol, which results in progressive neurodegeneration. Although the age of onset is variable, classical NPC1 is a pediatric disease. Identification of biomarkers that correlate with clinical phenotype and respond to therapeutic interventions will be essential for developing effective therapeutic interventions. A&#x3b2; peptides and Tau protein are primary components of amyloid plaques and neurofibrillary tangles, respectively, which are major pathological features in neurodegenerative disorders. Cerebrospinal fluid (CSF) levels of total Tau, a biomarker of axonal damage, were elevated ~3-fold (p&#x2009;<&#x2009;0.0001) in 106 individuals with Niemann-Pick disease, type C1, relative to age-appropriate comparison samples. Baseline CSF total Tau levels correlated with clinical measures of disease severity. Specifically, CSF total Tau levels decreased with increased age of neurological onset (rs&#x2009;=&#x2009;-0.42, FDR adj. p&#x2009;<&#x2009;0.0001) and increased with increased Annual Severity Increment Score (rs&#x2009;=&#x2009;0.52, FDR adj. p&#x2009;<&#x2009;0.0001). Baseline CSF total Tau levels were decreased 40% (p&#x2009;=&#x2009;0.0066) in individuals being treated with miglustat, and longitudinal analysis substantiated this observation with a 40% decrease (p&#x2009;<&#x2009;0.0001, 95% CI 32%-47.4%). Longitudinal analysis also showed a significant (p&#x2009;=&#x2009;0.004) decrease of 19% (95% CI 7%-30%) in total Tau levels associated with intrathecal 2-hydroxypropyl-&#x3b2;-cyclodextrin therapy. These data show that CSF total Tau levels are significantly increased in individuals with NPC1, positively correlated with increased disease severity, and respond to therapeutic interventions.

Humans↗

Diagnosis of Niemann-Pick disease using a simple and sensitive fluorimetric assay of sphingomyelinase activity.

Phosphodiesterase activity of cultured cells was determined with bis-(4-methylumbelliferyl) phosphate as substrate. In the presence of Triton X-100 an acid component was evident and results indicated that this enzyme was identical with sphingomyelinase. Acid phosphodiesterase activity was specifically inhibited by sphingomyelin. In fibroblasts from patients with Niemann-Pick diseases types A, B and C, acid phosphodiesterase activity was deficient whereas neutral activity was normal. Neutral activity could, however, be removed by acid precipitation or by binding to DEAE-cellulose. Hence a simple and sensitive fluorimetric method is described for the assay of sphingomyelinase activity in the diagnosis of Niemann-Pick disease.

Adult↗

Sex-dependent upregulation in oxylipins involved in inflammation resolution in the cerebellum of Niemann-Pick disease C1 mice.

Unresolved inflammation in the cerebellum is implicated in motor and cognitive decline in Niemann-Pick disease type C (NPC), a neurodegenerative lysosomal storage disorder caused by pathogenic mutations in the Npc1 gene encoding a cholesterol transporter protein. It is unclear whether unresolved inflammation in NPC stems from impairments in lipid-mediated resolution. For this reason, free lipid mediators (i.e., oxylipins) involved in inflammation resolution, as well as esterified lipid mediators known to regulate the bioavailability of free oxylipins were quantified using Reverse-Phase Ultra- Performance Liquid Chromatography coupled to negative Electrospray Ionization and Triple Quadrupole Tandem Mass Spectrometry (RP-UPLC-ESI(-)-QqQ-MS/MS) in Npc1 knock-in (NPC1ki) and Wildtype (WT) mice. Total cholesterol and fatty acids including polyunsaturated fatty acid (PUFA) precursors to oxylipins, were quantified using Gas Chromatography coupled to Flame Ionization Detection (GC-FID). Compared to WT mice, female NPC1ki mice, but not males, exhibited significantly elevated levels of free pro-resolving fatty acid epoxides (EpETrE and EpDPE) from the cytochrome P450 (CYP) pathway. Esterified mono- and dihydroxy lipid mediators derived from the lipoxygenase (LOX) and soluble epoxide hydrolase (sEH) pathways were mainly increased in NPC1ki females, suggesting enhanced sequestration of pro-inflammatory LOX and sEH metabolites. While PUFAs and cholesterol concentrations were not significantly different between groups, myristic (C14:0) and palmitoleic acid (C16:1n-7) were significantly elevated in female NPC1ki mice compared to WT controls. These findings suggest sex-specific adaptations in inflammation resolution pathways in NPC, with females exhibiting distinct inflammatory responses that may drive sex-related differences in disease pathogenesis. Our findings underscore the need for sex-specific therapeutic approaches to improve NPC treatment outcomes.

Animals↗

Niemann-Pick disease type D: lipid analyses and studies on sphingomyelinases.

Lipids and sphingomyelinase activity were studied in spleen, liver, and brain tissues of a 13-year-old boy with Niemann-Pick disease type D (NPD-D). The greatest lipid changes occurred in spleen; cholesterol, cholesterol esters, total phospholipids, sphingomyelin, and bis-(monoacylglyceryl)phosphate were increased above normal range. In liver, striking increases were observed in cholesterol and bis-(monoacylglyceryl)phosphate. Minor changes in neutral and acidic glycolipid patterns occurred in liver, spleen, and brain. Sphingomyelinase activity (optimal at pH 5.0) was elevated above mean control levels in liver and spleen, but not in brain, kidney, or leukocytes. Enzyme properties were generally normal. Activity of NPD-D liver crude homogenate, but not that of normal liver homogenates, was inhibited at high protein concentrations. Activity levels of a second sphingomyelinase, optimal at pH 7.4, in NPD-D brain were apparently normal. These findings are generally consistent with the classification of NPD-D as a sphingomyelin lipidosis.

Adolescent↗

Lactosyl ceramidosis: deficient activity of neutral beta-galactosidase in liver and cultivated fibroblasts?

Neutral beta-galactosidase was partially purified from liver of normal controls, a patient with Niemann-Pick disease type A and the previously described patient with lactosyl ceramidosis using Concanavalin A-Sepharose adsorption and Sephadex G-100 gel filtration. The partially purified fractions were essentially free of galactosyl ceramide beta-galactosidase and GM1 beta-galactosidase activities. The normal and Niemann-Pick fractions were found to hydrolyze lactosyl ceramide, in the presence of sodium taurodeoxycholate, at a pH optimum of 5.6 as well as aryl beta-galactosides and aryl beta-glucosides at pH 6.2. The corresponding fraction from the lactosyl ceramidosis liver contained only 1--4% of the normal activity towards artificial substrates and lactosyl ceramide. Cross-reacting material identical to the normal was demonstrated in this fraction with antiserum raised against purified neutral beta-galactosidase, but no activity was observed in the precipitin line when stained with naphthol AS-LC-beta-galactoside or naphthol AS-LC-beta-glucoside. A similar deficiency of neutral beta-galactosidase activity was demonstrated in cultivated fibroblasts of the patient with lactosyl ceramidosis. Following adsorption on Concanavalin A-Sepharose and anti-GM1 beta-galactosidase antibody-Sepharose conjugates and chromatography on DEAE cellulose, fibroblast lysates from the patient exhibited 3% of normal activity towards 4-methyl-umbelliferyl beta-glucoside at pH 6.2 and 12% of normal activity towards lactosyl ceramide at pH 5.6. These data suggest that neutral beta-galactosidase may have an in vivo role in the cleavage of lactosyl ceramide and that a deficiency of this activity may be related to the lactosyl ceramide accumulation observed in the patient with lactosyl ceramidosis.

Cells, Cultured↗

Determination of serum acid phosphatase in Gaucher's disease using 4-methylumbelliferyl phosphate.

We describe a new assay that is useful for identifying individuals who may be affected with Gaucher's disease. The assay involves the determination of serum acid phosphatase activity using the fluorogenic substrate 4-methylumbelliferyl phosphate. The assay measures acid phosphatase activity at pH 6.0 in the presence of 3.0 M 2-mercaptoethanol and requires a 5 microliter serum sample and a 15-min incubation period. Under these conditions, 2-mercaptoethanol preferentially inhibited the acid phosphatase activity in control serum but did not inhibit the elevated acid phosphatase present in the serum of patients with Gaucher's disease. Using this assay, we observed a 5-50-fold elevation in serum acid phosphatase activity in 8 patients with the adult, non-neuropathic form of Gaucher's disease when compared to control serum assayed under the same conditions. Serum from several heterozygotes free from pathology exhibited normal acid phosphatase activity when assayed at pH 6.0 in the presence of 2-mercaptoethanol. Acid phosphatase activity in serum from patients with prostatic cancer can be distinguished from that in Gaucher serum on the basis of the well-documented sensitivity of the former to inhibition by sodium tartrate. A serum sample from a patient with Niemann-Pick disease exhibited a mild elevation in tartrate-resistant acid phosphatase activity so that conclusive diagnosis of Gaucher's disease requires assaying leukocytes or fibroblasts from suspected patients for glucocerebroside:beta-glucosidase activity.

Acid Phosphatase↗

Studies on drug-induced lipidosis: VII. Effects of bis-beta-diethyl-aminoethylether of hexestrol, chloroquine, homochlorocyclizine, prenylamine, and diazacholesterol on the lipid composition of rat liver and kidney.

4,4'-Bis (beta-diethylaminoethoxy)-alpha, beta-diethyldiphenylethane (DH), which had been shown to induce a type of lipidosis resembling Niemann-Pick disease, was given to rats at a dose of 20, 50, 100, and 150 mg/kg body weight per day for 1 or 2 weeks. An enlargement of the liver with marked increases in free cholesterol, total phospholipids, and phosphatidylinositol took place by administration of a larger dose. The increase in bis (monoacylglyceryl) phosphate (BMGP), which is peculiar to this kind of drug-induced lipidosis, was dependent upon the dose of the drug as well as the length of time. Similar changes were also observed in kidney. Among several other drugs tested, chloroquine and diazacholesterol brought on as much increase in BMGP as treatment with DH.

Animals↗

Heritable catabolic and anabolic disorders of lipid metabolism.

The principal manifestations and metabolic defects in ten heritable disorders of lipid metabolism are discussed. Facile procedures have been developed for the diagnosis of patients with these conditions, the identification of heterozygous carriers, and the prenatal detection of any of these diseases. Enzyme replacement appears promising for patients with Fabry's disease and Gaucher's disease who do not have central nervous system damage. The clinical and biochemical abnormalities that occur in patients with a novel inherited disorder of ganglioside anabolism are described.

Adult↗

Activation of pro-survival autophagy by a small molecule promoting p62 oligomerization.

Autophagy is a critical mechanism of cellular quality control, orchestrated by selective autophagy receptor (SAR) proteins. Pharmacologically enhancing the cargo-targeting capacity of SARs presents an attractive but underexplored strategy for the precise therapeutic activation of autophagy. Here, we characterize SQ-1, a small-molecule activator of autophagy that engages the prototypical SAR protein p62/sequestosome-1 (SQSTM1). We show that SQ-1 sensitizes p62 to oxidation and promotes its disulfide-mediated oligomerization in response to mitochondrial reactive oxygen species (ROS). This ROS-dependent activation of p62-mediated selective autophagy enhances the clearance of ROS-generating mitochondria and restores cell viability in models of Niemann-Pick type C1 disease, which is marked by impaired autophagic flux. In summary, the unique mode of action of SQ-1 enables self-regulated autophagy activation, offering a potential therapeutic strategy for lysosomal storage disorders and a broader spectrum of age-related diseases characterized by defective autophagy.

Niemann-Pick type C1 disease↗

Discovery of novel diagnostic biomarkers of hepatocellular carcinoma associated with immune infiltration.

OBJECTIVE: Diagnosis of hepatocellular carcinoma (HCC) remains challenging for clinicians. Machine learning approaches and big data analyses are viable strategies for identifying HCC diagnostic markers. MATERIALS AND METHODS: In this study, we downloaded mRNA expression profiles of HCC from the GEO database and used random forest and machine learning algorithms, such as least absolute shrinkage and selection operator, to screen for reliable diagnostic genes. Disease Ontology, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Set Enrichment Analysis enrichment analyses were performed to explore differential gene functions and disease pathways. CIBERSORT was performed to calculate the immune cell infiltration of HCC and the correlation between diagnostic genes and immune cells. Cell experiments were performed to evaluate the function of R-spondin 3 (RSPO3) in HCC cells. Immunohistochemical staining was used to evaluate the protein expression of CD138, CD206 and iNOS. RESULTS: The results indicated that extracellular matrix protein 1 (ECM1), Niemann-Pick C1-Like 1 (NPC1L1) and RSPO3 were down-regulated in HCC compared with the normal group (p&#x2009;<&#x2009;0.05), which was validated in clinical tissue samples. Moreover, ECM1, NPC1L1 and RSPO3 had high diagnostic values (AUC > 0.75) for HCC in both training and test groups. Immuno-infiltration analysis revealed that ECM1 and RSPO3 were highly positively correlated with neutrophil and macrophage M2 levels, whereas they were negatively correlated with Tregs. RSPO3-si affected cell proliferation and apoptosis in HCC. Furthermore, RSPO3 exhibited a positive correlation with tumour progression, the proportion of plasma cells and M2 macrophages in mice, while showing a negative association with M1 macrophages. CONCLUSION: The present study identified ECM1, NPC1L1 and RSPO3 as new diagnostic biomarkers for HCC based on normal and diseased samples from HCC, meanwhile the pro-oncogenic function of RSPO3 and its regulation on immune infiltration have been confirmed.

Carcinoma, Hepatocellular↗