A 20-Year Longitudinal Study of Plasma Chitotriosidase Activity in Treated Gaucher Disease Type 1 and 3 Patients—A Qualitative and Quantitative Approach

Chitotriosidase is an enzyme produced and secreted in large amounts by activated macrophages, especially macrophages loaded with phagocytozed glycosphingolipid in Gaucher disease. Macrophages phagocytose decayed blood cells that contain a lot of sphingolipid-rich cell membranes. In Gaucher disease, due to a deficit in beta-glucocerebrosidase activity, the phagocytozed substrate glucocerebroside cannot undergo further catabolism. In such a situation, macrophages secrete chitotriosidase in proportion to the degree of overload. Gaucher disease (GD) is a recessively inherited disorder resulting in storage of glucosylceramide (GlcCer) in lysosomes of tissue macrophages. It is directly caused by the deficiency of beta-glucocerebrosidase (GBA) activity. Chitotriosidase has been measured systematically each year in the same group of 49 patients with type 1 and 3 GD for over 20 years. Our analysis showed that chitotriosidase is very sensitive biomarker to enzyme replacement therapy (ERT). The response to treatment introduction is of an almost immediate nature, lowering pathologically high chitotriosidase levels by a factor of 2 in a time scale of 8 months, on average. Long term enzyme replacement therapy (ERT) brings chitotriosidase activity close to reference values. Finally, reducing the dose of ERT quickly boosts chitotriosidase activity, but restoring the initial dose of treatment brings chitotriosidase level of activity back onto the decreasing time trajectory.

Venglustat combined with imiglucerase for neurological disease in adults with Gaucher disease type 3: the LEAP trial

Gaucher disease type 3 is a chronic neuronopathic disorder with wide-ranging effects, including hepatosplenomegaly, anaemia, thrombocytopenia, skeletal disease and diverse neurological manifestations. Biallelic mutations in GBA1 reduce lysosomal acid β-glucosidase activity, and its substrates, glucosylceramide and glucosylsphingosine, accumulate. Enzyme replacement therapy and substrate reduction therapy ameliorate systemic features of Gaucher disease, but no therapies are approved for neurological manifestations. Venglustat is an investigational, brain-penetrant, glucosylceramide synthase inhibitor with potential to improve the disease by rebalancing influx of glucosylceramide with impaired lysosomal recycling. The Phase 2, open-label LEAP trial (NCT02843035) evaluated orally administered venglustat 15 mg once-daily in combination with maintenance dose of imiglucerase enzyme replacement therapy during 1 year of treatment in 11 adults with Gaucher disease type 3. Primary endpoints were venglustat safety and tolerability and change in concentration of glucosylceramide and glucosylsphingosine in CSF from baseline to Weeks 26 and 52. Secondary endpoints included change in plasma concentrations of glucosylceramide and glucosylsphingosine, venglustat pharmacokinetics in plasma and CSF, neurologic function, infiltrative lung disease and systemic disease parameters. Exploratory endpoints included changes in brain volume assessed with volumetric MRI using tensor-based morphometry, and resting functional MRI analysis of regional brain activity and connectivity between resting state networks. Mean (SD) plasma venglustat AUC0-24 on Day 1 was 851 (282) ng•h/ml; Cmax of 58.1 (26.4) ng/ml was achieved at a median tmax 2.00 h. After once-daily venglustat, plasma concentrations (4 h post-dose) were higher compared with Day 1, indicating ∼2-fold accumulation. One participant (Patient 9) had low-to-undetectable venglustat exposure at Weeks 26 and 52. Based on mean plasma and CSF venglustat concentrations (excluding Patient 9), steady state appeared to be reached on or before Week 4. Mean (SD) venglustat concentration at Week 52 was 114 (65.8) ng/ml in plasma and 6.14 (3.44) ng/ml in CSF. After 1 year of treatment, median (inter-quartile range) glucosylceramide decreased 78% (72, 84) in plasma and 81% (77, 83) in CSF; median (inter-quartile range) glucosylsphingosine decreased 56% (41, 60) in plasma and 70% (46, 76) in CSF. Ataxia improved slightly in nine patients: mean (SD, range) total modified Scale for Assessment and Rating of Ataxia score decreased from 2.68 [1.54 (0.0 to 5.5)] at baseline to 1.55 [1.88 (0.0 to 5.0)] at Week 52 [mean change: -1.14 (95% CI: -2.06 to -0.21)]. Whole brain volume increased slightly in patients with venglustat exposure and biomarker reduction in CSF (306.7 ± 4253.3 mm3) and declined markedly in Patient 9 (-13894.8 mm3). Functional MRI indicated stronger connectivity at Weeks 26 and 52 relative to baseline between a broadly distributed set of brain regions in patients with venglustat exposure and biomarker reduction but not Patient 9, although neurocognition, assessed by Vineland II, deteriorated in all domains over time, which illustrates disease progression despite the intervention. There were no deaths, serious adverse events or discontinuations. In adults with Gaucher disease type 3 receiving imiglucerase, addition of once-daily venglustat showed acceptable safety and tolerability and preliminary evidence of clinical stability with intriguing but intrinsically inconsistent signals in selected biomarkers, which need to be validated and confirmed in future research.

Inhibition of invasion and metastasis of human liver cancer HCCLM3 cells by portulacerebroside A

CONTEXT

Portulacerebroside A (PCA) is a novel cerebroside compound isolated from Portulaca oleracea L. (Portulacaceae), an edible and medicinal plant distributed in the temperate and tropical zones worldwide.

OBJECTIVE

This study investigates the effects of PCA in human liver cancer HCCLM3 cells on metastasis and invasion.

MATERIALS AND METHODS

After the cells were treated with PCA (2.5, 5, and 10 μg/ml) for 6, 12, 24, or 48 h, adhesion, transwell invasion, and scratch tests were conducted and cell functions were evaluated. Western blot and FQ-RT-PCR assays explored the mechanism of PCA-inhibited invasion and metastasis in the cells.

RESULTS

The adhesion rate of the cells was suppressed at 0.5 h (79.4 ± 1.0, 68.7 ± 1.3, and 58.1 ± 1.3%, versus 100 ± 1.5% in the control), 1 h (78.2 ± 1.2, 70.9 ± 1.6, and 55.4 ± 1.9%, versus 100 ± 1.2% in the control), and 1.5 h (71.6 ± 1.1, 62.3 ± 0.9, and 50.4 ± 0.9%, versus 100 ± 1.1% in the control). The 24 h invasion ability was decreased (356.6 ± 11.2, 204.0 ± 17.6, and 113.0 ± 9.5%, versus 443.6 ± 15.4% in the control). The migration capability was also restrained by PCA for 24 h (324.8 ± 25.4, 250.4 ± 21.0, and 126.3 ± 10.1, versus 381.6 ± 30.6 in the control) and 48 h (470.3 ± 34.3, 404.0 ± 19.7, and 201.0 ± 15.4, versus 752.0 ± 63.6 in the control). There was an increase in the mRNA and protein expression levels of TIMP-2 and nm23-H1, inhibition in the mRNA expression of MTA1, MMP-2, and MMP-9, and suppression in the protein expression of MTA1, RhoA, Rac1/Cdc42, MMP-2, but not RhoC and MMP-9.

CONCLUSION

PCA suppresses the invasion and metastasis of HCCLM3 cells possibly by modulation of the mRNA and protein expression of related parameters. This is the first study to reveal a new potential therapeutic application of PCA in antimetastatic therapy for liver cancer.

Velaglucerase alfa, a human recombinant glucocerebrosidase enzyme replacement therapy for type 1 Gaucher disease

Gaucher disease (GD) is caused by a deficiency of the lysosomal enzyme glucocerebrosidase, which results in the accumulation of its substrate, glucocerebroside, in macrophages. This excess in lipid storage within macrophages (subsequently recognized as Gaucher cells) leads to the development of disease, which presents clinical features including anemia, thrombocytopenia and hepatosplenomegaly, and can also lead to the development of neurological problems or bone disease. Velaglucerase alfa is a gene-activated human recombinant glucocerebrosidase being developed by Shire Human Genetic Therapies Inc as an enzyme replacement therapy for type 1 GD. In vitro, velaglucerase alfa was internalized by human macrophages more rapidly than imiglucerase, which has been the sole standard of care for GD for over 15 years. Clinical trials in patients with GD demonstrated that the safety and efficacy of velaglucerase alfa appeared to be comparable with historical imiglucerase data, although head-to-head data were unavailable. Recent problems with the production of imiglucerase led to the unanticipated introduction of velaglucerase alfa to patients with GD through a pre-approval expanded access protocol. Whether this will prove beneficial, in terms of uptake and prescribing of the enzyme, remains to be seen in a market dominated by imiglucerase.

Glucocerebroside ameliorates the metabolic syndrome in OB/OB mice

Glucocerebroside (GC) is a naturally occurring glycolipid that may alter natural killer T (NKT) cell function. To determine the effect of GC on the metabolic derangements and immune profile in leptin-deficient mice, Ob/Ob mice were treated by daily injections of GC for 8 weeks and followed for various metabolic and immunological parameters. Marked amelioration of the metabolic alterations characteristic of leptin-deficient mice was observed in GC-treated animals compared with controls. A significant decrease in liver size and hepatic fat content were observed in GC-treated mice. Near-normalization of glucose tolerance and decreased serum triglyceride levels were observed. Fluorescence-activated cell sorting analysis of peripheral and intrahepatic lymphocytes revealed a 1.6-fold increase of the peripheral/intrahepatic NKT lymphocyte ratio. A 33% decrease of serum interferon-gamma level and a 2.6-fold increase of serum interleukin 10 level were noted in GC-treated mice. Immune modulation by GC may have a role in the treatment of nonalcoholic steatohepatitis and other immune-mediated disorders.

Ceramide-beta-D-glucuronide: synthesis, digestion, and suppression of early markers of colon carcinogenesis

Dietary sphingolipids inhibit chemically induced colon cancer in mice. The most likely mediators of this effect are the metabolites ceramide (Cer) and sphingosine, which induce growth arrest and apoptosis in transformed cells. Sphingolipids are digested in both the upper and the lower intestine; therefore, a more colon-specific method of delivery of sphingolipids might be useful. A Cer analogue with a D-glucuronic acid attached at the primary hydroxyl of N-palmitoyl-D-sphingosine (Cer-beta-glucuronide) was synthesized and evaluated as a substrate for Escherichia coli beta-glucuronidase and colonic digestion, as well as for suppression of early events in colon carcinogenesis in CFI mice treated with 1,2-dimethylhydrazine. Purified beta-glucuronidase (EC 3.2.1.31) and colonic segments (as a source of colonic enzymes and microflora) hydrolyzed Cer-beta-glucuronide to release Cer, as analyzed by tandem mass spectrometry. More than 75% of the Cer-beta-glucuronide was cleaved in an 8-h incubation with the colonic segments. When Cer-beta-glucuronide was administered for 4 weeks as 0.025% and 0.1% of the diet (AIN 76A) to 1,2-dimethylhydrazine-treated mice, there were significant reductions in colonic cell proliferation, as determined by in vivo BrdUrd incorporation, and in the appearance of aberrant crypt foci. The effect of dietary Cer-beta-glucuronide on aberrant crypt foci correlated significantly with the length of the colon, which suggests that Cer-beta-glucuronide was most effective when there was a larger compartment for digestion. Thus, synthetic sphingolipids that target the colon for the release of the bioactive backbones offer a promising approach to colon cancer prevention.