Phenotype, diagnosis, and treatment of Gaucher's disease

Molecular mechanisms of the ambroxol action in Gaucher disease and GBA1 mutation-associated Parkinson disease

Glucocerebrosidase (GCase), encoded by the GBA1 gene, is one of the lysosomal enzymes responsible for hydrolyzing the glycosphingolipids. Deficiency in GCase activity (in patients with two defective alleles of GBA1) leads to glucosylceramide storage in lysosomes which in turn results in the development of the Gaucher diseases, a lysosomal storage disorder, while a heterozygous state may be correlated with the GBA1 mutation-associated Parkinson disease. One of the proposed forms of therapy for these two conditions is the use of pharmacological chaperones which work by facilitating the achievement of the correct conformation of abnormally folded enzymes. Several compounds with chaperone activities against GCase have already been tested, one of which turned out to be ambroxol. Studies conducted on the action of this compound have indeed indicated its effectiveness in increasing GCase levels and activity. However, some data have begun to question its activity as a chaperone against certain GCase variants. Then, a number of articles appeared pointing to other mechanisms of action of ambroxol, which may also contribute to the improvement of patients' condition. This paper summarizes the biological mechanisms of action of ambroxol in Gaucher disease and GBA1 mutation-associated Parkinson disease, focused on its activity as a chaperone, modulator of ERAD pathways, inducer of autophagy, and pain reliever in cellular and animal models as well as in patients. The effects of these activities on the reduction of disease markers and symptoms in patients are also discussed. Consideration of all the properties of ambroxol can help in the appropriate choice of therapy and the determination of the effective drug dose.

Identification of patient-reported outcomes measures (PROMs) and patient-reported experiences measures (PREMs) in Gaucher disease in Spain

BACKGROUND

Patient-reported outcome measures (PROMs) and patient-reported experiences measures (PREMs) are crucial for understanding the impact of GD on quality of life and patient's perceptions on care, but also to guide decision-making processes. Nevertheless, no specific PREMs in GD have been published, neither PROMs for Spanish GD patients have been developed.

METHODS

Two project coordinators selected key-points to be included in a PROMs/PREMs questionnaire, and the scientific committee and a group of expert patients contributed to the initial draft. Then, 9 meetings with experts were held to discuss controversial points. After, a questionnaire with 103 items regarding symptomatology, aspects of daily life and care experience was developed. Finally, it was conducted a Delphi survey among a multidisciplinary group of experts in GD.

RESULTS

Consensus was reached on 85 out of the 103 items. Recommendations on PROMs and PREMs regarding symptomatology, aspects of daily life and care experience were obtained. Consensus was reached on the importance of considering fatigue, concentration problems, and communication issues in GD patients using 5-step analog scales. Panelists recommended asking GD patients about the impact on social functioning and work/school performance. Finally, consensus was reached on considering care experiences, such as treatment satisfaction, treatment interruptions or transitions and healthcare professionals involved in patient's management to perceive patient's perceptions.

CONCLUSION

This expert consensus may help developing GD-specific PROMs/PREMs for improving GD management. Properly developed and validated PROMs/PREMs may help decision-making, establishing patient-tailored therapeutic and follow-up goals.

A review of type 3 Gaucher disease: unique neurological manifestations and advances in treatment

Gaucher disease (GD) is a rare lysosomal storage disease that is caused by mutations in the GBA gene. It is classified into three main phenotypes according to the patient's clinical presentation. Of these, chronic neuronopathic GD (GD3) is characterized by progressive neurological damage. Understanding the unique neurological manifestations of GD3 has important diagnostic and therapeutic implications. Our article summarizes the neurological symptoms specific to GD3 and related therapeutic advances, and it highlights the relevance of the gene to clinical symptoms, so as to provide a reference for the diagnosis and treatment of GD3.

Evaluation of a Liquid Chromatography-Tandem Mass Spectrometry Method for the Analysis of Glucosylceramide and Galactosylceramide Isoforms in Cerebrospinal Fluid of Parkinson's Disease Patients

Mutations in GBA1, encoding glucocerebrosidase beta 1 (GCase), are the most common genetic risk factor for Parkinson's disease (PD). GCase dysfunction leads to an accumulation of glucosylceramide (GluCer) substrates in different organs and fluids. Despite the challenges in quantifying GluCer isoforms in biological samples, their potential clinical interest as PD biomarkers justifies the development of robust assays. An extensively evaluated high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for quantifying 14 GluCer and galactosylceramide (GalCer) isoforms in human cerebrospinal fluid (CSF) samples is presented. Sample pretreatment, HPLC, and MS/MS parameters were optimized. Evaluation was performed according to the recommendations of the Clinical and Laboratory Standards Institute and European Medicines Agency guidelines. Four 7-point calibration curves were generated, with a linearity interval from 2.5 to 200 nM (R2 ≥ 0.995). The limit of quantification was set at 5 nM. Between-run precision and accuracy were up to 12.5 and 9%, respectively. After method validation, we measured the levels of GluCer and GalCer isoforms in CSF human samples, including 6 healthy controls (HC), 22 idiopathic GBA1 wild-type PD (iPD) patients, and 5 GBA1-associated PD (PD-GBA) patients. GluCer/GalCer median ratios were found to be higher in the CSF of PD-GBA patients, particularly in severe GBA1 mutations, than those in iPD and HC. The observed trends in GluCer/GalCer ratios among groups provide novel information for the comprehensive analysis of sphingolipids as potential biomarkers of PD.

Neurological symptoms in adults with Gaucher disease: a systematic review

INTRODUCTION

Gaucher disease (GD) is classically divided into three types, based on the presence or absence of neurological signs and symptoms. However, presentation can be highly variable in adulthood, and this aspect has not been adequately addressed in the literature so far. We performed a systematic literature review to analyze the entire spectrum of neurological manifestations in adult patients previously classified as GD type I, II, or III, evaluating the role of variants in different neurological manifestations.

METHODS

We searched databases for studies reporting clinical data of adult GD patients (age ≥ 18). Data extraction included GD types, GBA1 variants, age at disease onset and diagnosis, duration of GD, and age at onset and type of neurological symptoms reported.

RESULTS

Among 4190 GD patients from 85 studies, 555 exhibited neurological symptoms in adulthood. The median age at evaluation was 46.8 years (IQR 26.5), age at neurological symptoms onset was 44 years (IQR 35.1), and age at GD clinical onset was 23 years (IQR 23.4). Parkinsonism, including Parkinson's disease and Lewy Body dementia, was the most reported neurological manifestation. Other symptoms and signs encompassed oculomotor abnormalities, peripheral neuropathy, seizures, myoclonus, and cerebellar, cognitive and psychiatric symptoms. The genotype N370S/N370S mostly presented with Parkinsonism and the L444P variant with severe and earlier neurological symptoms.

CONCLUSION

The findings of this systematic review highlight: (1) the relevance of a comprehensive neurological assessment in GD patients, and (2) the importance of considering possible undiagnosed GD in adult patients with mild systemic symptoms presenting unexplained neurological symptoms.

Interaction between α-Synuclein and Bioactive Lipids: Neurodegeneration, Disease Biomarkers and Emerging Therapies

The present review provides a comprehensive examination of the intricate dynamics between α-synuclein, a protein crucially involved in the pathogenesis of several neurodegenerative diseases, including Parkinson's disease and multiple system atrophy, and endogenously-produced bioactive lipids, which play a pivotal role in neuroinflammation and neurodegeneration. The interaction of α-synuclein with bioactive lipids is emerging as a critical factor in the development and progression of neurodegenerative and neuroinflammatory diseases, offering new insights into disease mechanisms and novel perspectives in the identification of potential biomarkers and therapeutic targets. We delve into the molecular pathways through which α-synuclein interacts with biological membranes and bioactive lipids, influencing the aggregation of α-synuclein and triggering neuroinflammatory responses, highlighting the potential of bioactive lipids as biomarkers for early disease detection and progression monitoring. Moreover, we explore innovative therapeutic strategies aimed at modulating the interaction between α-synuclein and bioactive lipids, including the development of small molecules and nutritional interventions. Finally, the review addresses the significance of the gut-to-brain axis in mediating the effects of bioactive lipids on α-synuclein pathology and discusses the role of altered gut lipid metabolism and microbiota composition in neuroinflammation and neurodegeneration. The present review aims to underscore the potential of targeting α-synuclein-lipid interactions as a multifaceted approach for the detection and treatment of neurodegenerative and neuroinflammatory diseases.

GBA-associated Parkinson's disease in Hungary: clinical features and genetic insights

INTRODUCTION

Parkinson's disease (PD) has a complex genetic background involving both rare and common genetic variants. Although a small percentage of cases show a clear Mendelian inheritance pattern, it is much more relevant to identify patients who present with a complex genetic profile of risk variants with different severity. The ß-glucocerebrosidase coding gene (GBA1) is recognized as the most frequent genetic risk factor for PD and Lewy body dementia, irrespective of reduction of the enzyme activity due to genetic variants.

METHODS

In a selected cohort of 190 Hungarian patients with clinical signs of PD and suspected genetic risk, we performed the genetic testing of the GBA1 gene. As other genetic hits can modify clinical features, we also screened for additional rare variants in other neurodegenerative genes and assessed the APOE-ε genotype of the patients.

RESULTS

In our cohort, we identified 29 GBA1 rare variant (RV) carriers. Out of the six different detected RVs, the highly debated E365K and T408M variants are composed of the majority of them (22 out of 32). Three patients carried two GBA1 variants, and an additional three patients carried rare variants in other neurodegenerative genes (SMPD1, SPG11, and SNCA). We did not observe differences in age at onset or other clinical features of the patients carrying two GBA1 variants or patients carrying heterozygous APOE-ε4 allele.

CONCLUSION

We need further studies to better understand the drivers of clinical differences in these patients, as this could have important therapeutic implications.

Gaucher Disease: A Glance from a Medicinal Chemistry Perspective

Rare diseases are particular pathological conditions affecting a limited number of people and few drugs are known to be effective as therapeutic treatment. Gaucher disease, caused by a deficiency of the lysosomal enzyme glucocerebrosidase, belongs to this class of disorders, and it is considered the most common among the Lysosomal Storage Diseases. The two main therapeutic approaches are the Enzyme Replacement Therapy (ERT) and the Substrate Reduction Therapy (SRT). ERT, consisting in replacing the defective enzyme by administering a recombinant enzyme, is effective in alleviating the visceral symptoms, hallmarks of the most common subtype of the disease whereas it has no effects when symptoms involve CNS, since the recombinant protein is unable to significantly cross the Blood Brain Barrier. The SRT strategy involves inhibiting glucosylceramide synthase (GCS), the enzyme responsible for the production of the associated storage molecule. The rational design of new inhibitors of GCS has been hampered by the lack of either the crystal structure of the enzyme or an in-silico model of the active site which could provide important information regarding the interactions of potential inhibitors with the target, but, despite this, interesting results have been obtained and are herein reviewed.

Study protocol of the GRoningen early-PD Ambroxol treatment (GREAT) trial: a randomized, double-blind, placebo-controlled, single center trial with ambroxol in Parkinson patients with a GBA mutation

BACKGROUND

To date, no disease modifying therapies are available for Parkinson's disease (PD). Since PD is the second most prevalent neurodegenerative disorder, there is a high demand for such therapies. Both environmental and genetic risk factors play an important role in the etiology and progression of PD. The most common genetic risk factor for PD is a mutation in the GBA1(GBA)-gene, encoding the lysosomal enzyme glucocerebrosidase (GCase). The mucolytic ambroxol is a repurposed drug, which has shown the property to upregulate GCase activity in-vitro and in-vivo. Ambroxol therefore has the potency to become a disease modifying therapy in PD, which was the reason to design this randomized controlled trial with ambroxol in PD patients.

METHODS

This trial is a single-center, double-blind, randomized, placebo-controlled study, including 80 PD patients with a GBA mutation, receiving either ambroxol 1800 mg/day or placebo for 48 weeks. The primary outcome measure is the Unified Parkinson's Disease Rating Scale motor subscore (part III) of the Movement Disorder Society (MDS-UPDRSIII) in the practically defined off-state at 60 weeks (after a 12-week washout period). Secondary outcomes include a 3,4-dihydroxy-6-18F-fluoro-I-phenylalanine ([18F]FDOPA) PET-scan of the brain, Magnetic Resonance Imaging (with resting state f-MRI and Diffusion Tensor Imaging), GCase activity, both intra- and extracellularly, sphingolipid profiles in plasma, Montreal Cognitive Assessment (MoCA), quality of life (QoL) measured by the Parkinson's Disease Questionnaire (PDQ-39) and the Non-Motor Symptom Scale (NMSS) questionnaire.

DISCUSSION

Ambroxol up to 1200 mg/day has shown effects on human cerebrospinal fluid endpoints, which supports at least passage of the blood-brain-barrier. The dose titration in this trial up to 1800 mg/day will reveal if this dose level is safe and also effective in modifying the course of the disease.

TRIAL REGISTRATION

NCT05830396. Registration date: March 20, 2023.

An increase in ER stress and unfolded protein response in iPSCs-derived neuronal cells from neuronopathic Gaucher disease patients

Gaucher disease (GD) is a lysosomal storage disorder caused by a mutation in the GBA1 gene, responsible for encoding the enzyme Glucocerebrosidase (GCase). Although neuronal death and neuroinflammation have been observed in the brains of individuals with neuronopathic Gaucher disease (nGD), the exact mechanism underlying neurodegeneration in nGD remains unclear. In this study, we used two induced pluripotent stem cells (iPSCs)-derived neuronal cell lines acquired from two type-3 GD patients (GD3-1 and GD3-2) to investigate the mechanisms underlying nGD by biochemical analyses. These iPSCs-derived neuronal cells from GD3-1 and GD3-2 exhibit an impairment in endoplasmic reticulum (ER) calcium homeostasis and an increase in unfolded protein response markers (BiP and CHOP), indicating the presence of ER stress in nGD. A significant increase in the BAX/BCL-2 ratio and an increase in Annexin V-positive cells demonstrate a notable increase in apoptotic cell death in GD iPSCs-derived neurons, suggesting downstream signaling after an increase in the unfolded protein response. Our study involves the establishment of iPSCs-derived neuronal models for GD and proposes a possible mechanism underlying nGD. This mechanism involves the activation of ER stress and the unfolded protein response, ultimately leading to apoptotic cell death in neurons.

Multiparametric magnetic resonance imaging of the liver and spleen in Gaucher disease

PURPOSE

To assess liver and spleen characteristics of a population with Gaucher disease (GD) using multiparametric MRI and MR elastography (MRE) for evaluation of diffuse liver and spleen disease, which includes liver fat fraction, liver and spleen volume and iron deposition, and liver and spleen stiffness correlated with DS3 Severity Scoring System for Gaucher disease (GD-DS3).

METHODS

We prospectively evaluated 41 patients with type 1 Gaucher disease using a 3.0 T MRI and MRE between January 2019 and February 2020. Clinical, laboratory, and imaging data was collected. Mann-Whitney, Kruskal-Wallis, and Spearman's correlation were applied to evaluate liver and spleen MRI and MRE, clinical and laboratory variables, and GD-DS3. ERT and SRT treatment groups were compared.

RESULTS

Hepatomegaly was seen in 15% and splenomegaly in 42% of the population. Moderate and strong and correlations were found between liver and spleen iron overload (rho = 0.537; p = 0.002); between liver and spleen volume (rho = 0.692, p < 0.001) and between liver and spleen stiffness (rho = 0.453, p = 0.006). Moderate correlations were found between liver stiffness and GD-DS3 (rho = 0.559; p < 0.001) and between splenic volume and GD-DS3 (rho = 0.524; p = 0.001).

CONCLUSION

The prevalence of hepatosplenomegaly, liver fibrosis, and liver iron overload in treated patients with GD is low, which may be related to the beneficial effect of treatment. Liver MRE and splenic volume correlate with severity score and may be biomarkers of disease severity.

The Expression and Secretion Profile of TRAP5 Isoforms in Gaucher Disease

BACKGROUND

Gaucher disease (GD) is caused by glucocerebrosidase (GCase) enzyme deficiency, leading to glycosylceramide (Gb-1) and glucosylsphingosine (Lyso-Gb-1) accumulation. The pathological hallmark for GD is an accumulation of large macrophages called Gaucher cells (GCs) in the liver, spleen, and bone marrow, which are associated with chronic organ enlargement, bone manifestations, and inflammation. Tartrate-resistant acid phosphatase type 5 (TRAP5 protein, ACP5 gene) has long been a nonspecific biomarker of macrophage/GCs activation; however, the discovery of two isoforms of TRAP5 has expanded its significance. The discovery of TRAP5's two isoforms revealed that it is more than just a biomarker of macrophage activity. While TRAP5a is highly expressed in macrophages, TRAP5b is secreted by osteoclasts. Recently, we have shown that the elevation of TRAP5b in plasma is associated with osteoporosis in GD. However, the role of TRAP isoforms in GD and how the accumulation of Gb-1 and Lyso-Gb-1 affects TRAP expression is unknown.

METHODS

39 patients with GD were categorized into cohorts based on bone mineral density (BMD). TRAP5a and TRAP5b plasma levels were quantified by ELISA. ACP5 mRNA was estimated using RT-PCR.

RESULTS

An increase in TRAP5b was associated with reduced BMD and correlated with Lyso-Gb-1 and immune activator chemokine ligand 18 (CCL18). In contrast, the elevation of TRAP5a correlated with chitotriosidase activity in GD. Lyso-Gb-1 and plasma seemed to influence the expression of ACP5 in macrophages.

CONCLUSIONS

As an early indicator of BMD alteration, measurement of circulating TRAP5b is a valuable tool for assessing osteopenia-osteoporosis in GD, while TRAP5a serves as a biomarker of macrophage activation in GD. Understanding the distinct expression pattern of TRAP5 isoforms offers valuable insight into both bone disease and the broader implications for immune system activation in GD.

Identification of ß-Glucocerebrosidase Activators for Glucosylceramide hydrolysis

Several novel chemical series were identified that modulate glucocerebrosidase (GCase). Compounds from these series are active on glucosylceramide, unlike other known GCase modulators. We obtained GCase crystal structures with two compounds that have distinct chemotypes. Positive allosteric modulators bind to a site on GCase and induce conformational changes, but also induce an equilibrium state between monomer and dimer.

The role of cardiac imaging in assessing the cardiac involvement of type 1 Gaucher disease: a case report with review of literature

BACKGROUND

Gaucher disease (GD) is a lysosomal storage disease that leads to the accumulation of glucocerebroside within reticuloendothelial cells, haematological, neurological, skeletal and abdominal organs. These clinical manifestations are common to all types of GD, but categorization depends on the absence of neurological involvement (type I) or its presence (type II and III). Cardiac involvement is rare and only reported in few cases, where valvular and aortic calcifications were associated with type IIIc. Other cardiac manifestations, such as constrictive pericarditis, pulmonary hypertension, myocardial infiltration, and restrictive cardiomyopathy, had also been reported.

CASE PRESENTATION

We report a case of a 72-year-old patient with known type 1 GD who presented with a sudden syncope during exercise. He reported also an exercise intolerance evolving for three months. Echocardiography found concentric left ventricular hypertrophy with segmental hypokinesis, bi-atrial enlargement, and mildly reduced ejection fraction. Mitral flow was in favour of grade II diastolic dysfunction with elevated filling pressure. Cardiac magnetic resonance (CMR) showed interstitial fibrosis in the basal infero-septal wall, probably due to the myocardial infiltration of GD. Due to the lack of echocardiographic and CMR hallmarks of cardiac GD, we conducted a literature review on similar findings.

CONCLUSION

This case illustrates the importance of non-invasive cardiac imaging in the diagnosis, prognosis and management of cardiac manifestations of GD.

Gaucher Disease or Acid Sphingomyelinase Deficiency? The Importance of Differential Diagnosis

Background: Gaucher disease is a lysosomal storage disorder caused by functional glucocerebrosidase enzyme deficiency. Hepatosplenomegaly and hematological complications are found in both Gaucher disease and Acid Sphingomyelinase Deficiency, which is caused by acid sphingomyelinase dysfunction. The possible overlap in clinical presentation can cause diagnostic errors in differential diagnosis. For this reason, in patients with an initial clinical suspicion of Gaucher disease, we aimed to carry out a parallel screening of acid sphingomyelinase and glucocerebrosidase. Methods: Peripheral blood samples of 627 patients were collected, and enzymatic activity analysis was performed on both glucocerebrosidase and acid sphingomyelinase. The specific gene was studied in samples with null or reduced enzymatic activity. Specific molecular biomarkers helped to achieve the correct diagnosis. Results: In 98.7% of patients, normal values of glucocerebrosidase activity excluded Gaucher disease. In 8 of 627 patients (1.3%), the glucocerebrosidase enzymatic activity assay was below the normal range, so genetic GBA1 analysis confirmed the enzymatic defect. Three patients (0.5%) had normal glucocerebrosidase activity, so they were not affected by Gaucher disease, and showed decreased acid sphingomyelinase activity. SMPD1 gene mutations responsible for Acid Sphingomyelinase Deficiency were found. The levels of specific biomarkers found in these patients further strengthened the genetic data. Conclusions: Our results suggest that in the presence of typical signs and symptoms of Gaucher disease, Acid Sphingomyelinase Deficiency should be considered. For this reason, the presence of hepatosplenomegaly, thrombocytopenia, leukocytopenia, and anemia should alert clinicians to analyze both enzymes by a combined screening. Today, enzyme replacement therapy is available for the treatment of both pathologies; therefore, prompt diagnosis is essential for patients to start accurate treatment and to avoid diagnostic delay.

Taliglucerase alfa in the longterm treatment of children and adolescents with type 1 Gaucher disease: the Albanian experience

Introduction

Enzyme replacement therapy is already recognized as the gold standard of care for patients with Gaucher disease. Taliglucerase alfa is one of the three alternatives recommended for treatment of Gaucher disease in children and adults.

Aim

This study aims to evaluate the long-term efficacy and safety of Taliglucerase alfa in children and adolescents with Type 1 Gaucher disease.

Patients and methods

Over a six-year period, we monitored the efficacy of continuous treatment in 10 patients by assessing various parameters, including hemoglobin concentration, platelet count, liver and spleen volume, bone mineral density, glucosylsphingosine level, chitotriosidase activity, and growth parameters. Safety was evaluated by immunogenicity and adverse event monitoring.

Results

The mean age of patients was 13.4 ± 3.6 years and the treatment duration was 60.24 ± 13.4 months. From baseline to end line the parameters change as follows: hemoglobin concentration improved from 12.7 (±1.3) to 14.6 (±1.5) and platelet count from 180 (±74) to 198 (±79). The spleen volume, was reduced by 46% (p = 0,007). The chitotriosidase activity decreased from 4,019.7 (±3,542.0) nmoles/ml/hr to 2,039.5 (±1,372.2) nmoles/ml/hr (46% reduction). Glucoylsphingosine level dropped from 119.2 (±70.4) ng/ml to 86.2 (±38.1) ng/ml, indicating a reduction of 28%. Bone mineral density Z-score, improved from -1.47 (±1.76) to -0.46 (±0.99) (69.7% reduction). Out of the 1,301 total administrations, our patients reported only 37 (2.8%) infusion-related adverse events which were mild and transitory.

Conclusion

Taliglucerase alfa exhibits good efficacy and a safe profile in the treatment of children and adolescents with Type 1 Gaucher disease.

The use of Ambroxol for the treatment of Gaucher disease: A systematic review

Gaucher disease (GD) is a heterogeneous condition requiring tailored treatment approaches. The aim of this systematic review was to synthesise and evaluate current evidence pertaining to the use of Ambroxol for the treatment of GD. Published and unpublished literature databases, conference proceedings and the reference lists of included studies were searched until 23 November 2023. A narrative synthesis was performed. Database search and risk of bias assessment were performed independently by two reviewers. Twenty-one studies (182 patients) were included. The evidence was low in quality. Variable responses to Ambroxol were observed. Response rates were 36% and 55% in two studies reporting on type 1 GD. One study found a 22% response rate in type 2 GD, whereas another study found 29% of patients with type 3 GD reported neurological improvements. No severe adverse events were reported in the literature, with mild and reversible side effects reported. Varying response rates are to be expected (29%-100%) when treating neurological manifestations. Varying degrees of symptomatic improvement for the treatment of GD were noted in the literature. Multidisciplinary team input and clinical judgement are advised to provide personalized treatment of this complex and multi-faceted condition.

Glucosylceramide in bunyavirus particles is essential for virus binding to host cells

Hexosylceramides (HexCer) are implicated in the infection process of various pathogens. However, the molecular and cellular functions of HexCer in infectious cycles are poorly understood. Investigating the enveloped virus Uukuniemi (UUKV), a bunyavirus of the Phenuiviridae family, we performed a lipidomic analysis with mass spectrometry and determined the lipidome of both infected cells and derived virions. We found that UUKV alters the processing of HexCer to glycosphingolipids (GSL) in infected cells. The infection resulted in the overexpression of glucosylceramide (GlcCer) synthase (UGCG) and the specific accumulation of GlcCer and its subsequent incorporation into viral progeny. UUKV and several pathogenic bunyaviruses relied on GlcCer in the viral envelope for binding to various host cell types. Overall, our results indicate that GlcCer is a structural determinant of virions crucial for bunyavirus infectivity. This study also highlights the importance of glycolipids on virions in facilitating interactions with host cell receptors and infectious entry of enveloped viruses.

Identification of GM1-Ganglioside Secondary Accumulation in Fibroblasts from Neuropathic Gaucher Patients and Effect of a Trivalent Trihydroxypiperidine Iminosugar Compound on Its Storage Reduction

Gaucher disease (GD) is a rare genetic metabolic disorder characterized by a dysfunction of the lysosomal glycoside hydrolase glucocerebrosidase (GCase) due to mutations in the gene GBA1, leading to the cellular accumulation of glucosylceramide (GlcCer). While most of the current research focuses on the primary accumulated material, lesser attention has been paid to secondary storage materials and their reciprocal intertwining. By using a novel approach based on flow cytometry and fluorescent labelling, we monitored changes in storage materials directly in fibroblasts derived from GD patients carrying N370S/RecNcil and homozygous L444P or R131C mutations with respect to wild type. In L444P and R131C fibroblasts, we detected not only the primary accumulation of GlcCer accumulation but also a considerable secondary increase in GM1 storage, comparable with the one observed in infantile patients affected by GM1 gangliosidosis. In addition, the ability of a trivalent trihydroxypiperidine iminosugar compound (CV82), which previously showed good pharmacological chaperone activity on GCase enzyme, to reduce the levels of storage materials in L444P and R131C fibroblasts was tested. Interestingly, treatment with different concentrations of CV82 led to a significant reduction in GM1 accumulation only in L444P fibroblasts, without significantly affecting GlcCer levels. The compound CV82 was selective against the GCase enzyme with respect to the β-Galactosidase enzyme, which was responsible for the catabolism of GM1 ganglioside. The reduction in GM1-ganglioside level cannot be therefore ascribed to a direct action of CV82 on β-Galactosidase enzyme, suggesting that GM1 decrease is rather related to other unknown mechanisms that follow the direct action of CV82 on GCase. In conclusion, this work indicates that the tracking of secondary storages can represent a key step for a better understanding of the pathways involved in the severity of GD, also underlying the importance of developing drugs able to reduce both primary and secondary storage-material accumulations in GD.

pH-Responsive Trihydroxylated Piperidines Rescue The Glucocerebrosidase Activity in Human Fibroblasts Bearing The Neuronopathic Gaucher-Related L444P/L444P Mutations in GBA1 Gene

Engineering bioactive iminosugars with pH-responsive groups is an emerging approach to develop pharmacological chaperones (PCs) able to improve lysosomal trafficking and enzymatic activity rescue of mutated enzymes. The use of inexpensive l-malic acid allowed introduction of orthoester units into the lipophilic chain of an enantiomerically pure iminosugar affording only two diastereoisomers contrary to previous related studies. The iminosugar was prepared stereoselectively from the chiral pool (d-mannose) and chosen as the lead bioactive compound, to develop novel candidates for restoring the lysosomal enzyme glucocerebrosidase (GCase) activity. The stability of orthoester-appended iminosugars was studied by 1 H NMR spectroscopy both in neutral and acidic environments, and the loss of inhibitory activity with time in acid medium was demonstrated on cell lysates. Moreover, the ability to rescue GCase activity in the lysosomes as the result of a chaperoning effect was explored. A remarkable pharmacological chaperone activity was measured in fibroblasts hosting the homozygous L444P/L444P mutation, a cell line resistant to most PCs, besides the more commonly responding N370S mutation.

The Degree of Cardiovascular Autonomic Dysfunction is not Different in GBA-Related and Idiopathic Parkinson's Disease Patients: A Case-Control Instrumental Evaluation

Background

Increased prevalence of cardiovascular autonomic failure might play a key role on Parkinson's disease (PD) progression of glucocerebrosidase gene (GBA)-mutated patients, determining a malignant phenotype of disease in these patients.

Objective

To objectively characterize, for the first time, the cardiovascular autonomic profile of GBA-mutated patients compared to idiopathic PD patients by means of cardiovascular reflex tests (CRTs).

Methods

This is a case-control (1 : 2) study on PD patients belonging to well-characterized prospective cohorts. For each PD patient carrying GBA variants, two idiopathic PD patients, matched for sex and disease duration at CRTs, were selected. Patients recruited in these cohorts underwent a complete clinical and instrumental evaluation including specific autonomic questionnaires, CRTs and extensive genetic analysis.

Results

A total of 23 GBA-PD patients (19 males, disease duration 7.7 years) were included and matched with 46 non-mutated PD controls. GBA-mutated patients were younger than controls (59.9±8.1 vs. 64.3±7.2 years, p = 0.0257) and showed a more severe phenotype. Despite GBA-mutated patients reported more frequently symptoms suggestive of orthostatic hypotension (OH) than non-mutated patients (39.1% vs 6.5%, p = 0.001), the degree of cardiovascular autonomic dysfunction, when instrumentally assessed, did not differ between the two groups, showing the same prevalence of neurogenic OH, delayed OH and cardiovascular reflex impairment (pathological Valsalva maneuver).

Conclusion

GBA-PD patients did not show different instrumental cardiovascular autonomic pattern than non-mutated PD. Our findings suggested that symptoms suggestive of OH should be promptly investigated by clinicians to confirm their nature and improve patient care and management.

Treatment-naive and post-treatment glucosylsphingosine (lyso-GL1) levels in a cohort of pediatric patients with Gaucher disease

Glucosylsphingosine (lyso-GL1) is a biomarker used to monitor disease and treatment response in Gaucher disease. Data from adults show that higher values of lyso-GL1 are associated with increased disease progression, however similar data in the pediatric population is lacking. In a cohort of pediatric patients, we present a relationship between lyso-GL1 value and Gaucher type, age, and treatment response. Data from this study may serve as a reference for providers monitoring children with Gaucher disease.

Uncovering a New Family Cluster of Gaucher Disease: A Case Report

Gaucher disease (GD) is a recessive autosomal lysosomal storage disorder caused by a deficiency in glucocerebrosidase, leading to the accumulation of undigested glycolipids in the lysosomes of monocytes and macrophages. Patients with GD exhibit a spectrum of phenotypic heterogeneity and are broadly classified into three subtypes. Type 1 is the most common and is not associated with neurological damage, while types 2 and 3 are more severe, presenting with acute neuropathic and subacute neuropathic symptoms, respectively. A thorough accurate initial multisystemic assessment is crucial for evaluating the damage to all potentially affected organs and determining the disease burden. This case report highlights the intricacies of GD type 1 by providing a thorough exploration of the clinical presentation and showcasing valuable insights into the unique manifestations of the disease. The key feature was his individual and family medical history, which allowed the identification and treatment of another case within the community.

Lipids as Emerging Biomarkers in Neurodegenerative Diseases

Biomarkers are molecules that can be used to observe changes in an individual's biochemical or medical status and provide information to aid diagnosis or treatment decisions. Dysregulation in lipid metabolism in the brain is a major risk factor for many neurodegenerative disorders, including frontotemporal dementia, Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Thus, there is a growing interest in using lipids as biomarkers in neurodegenerative diseases, with the anionic phospholipid bis(monoacylglycerol)phosphate and (glyco-)sphingolipids being the most promising lipid classes thus far. In this review, we provide a general overview of lipid biology, provide examples of abnormal lysosomal lipid metabolism in neurodegenerative diseases, and discuss how these insights might offer novel and promising opportunities in biomarker development and therapeutic discovery. Finally, we discuss the challenges and opportunities of lipid biomarkers and biomarker panels in diagnosis, prognosis, and/or treatment response in the clinic.

Patient reported outcomes of patients with Gaucher disease type 1 treated with eliglustat in real-world settings: The ELIPRO study

INTRODUCTION

Gaucher disease type 1 (GD1) is a rare genetic lysosomal storage disorder. Eliglustat is a first-line oral therapy for adult patients with GD1. The aim of the ELIPRO (ELIglustat Patient Reported Outcomes) study was to assess real-world outcomes of eliglustat treatment for over 1 year in patients with GD1, with a focus on patient-reported outcomes (PROs), including treatment adherence.

METHODS

This was a non-interventional, prospective, multicentric study. Patients were stratified according to their previous time on eliglustat: >6 months (Group1) and ≤ 6 months (Group2). The primary endpoint was adherence to eliglustat, measured by the eight-items Morisky Medication Adherence Scale (MMAS-8; scale of 0-8) at 6 months in Group2. Secondary endpoints were quality of life (QoL) measured by patient input using the European Quality of Life five-dimensional three-level [EQ-5D-3L] questionnaire, fatigue and pain measured by numeric rating scale [NRS; on a scale of 0-10], the evaluation of patient satisfaction level regarding eliglustat treatment measured by Likert scale [scale of 0-7] and treatment adherence at 12 months in both groups. The study also evaluated the safety and effectiveness of eliglustat in the adult GD1 population.

RESULTS

Sixty patients with GD1 (approximatively 52% male, mean age: 46.6 ± 13.9 years) were analyzed: 29 in Group1 and 31 in Group2. GD1 was mostly of mild severity (90%) and 95% of patients had extensive CYP2D6 metabolizer phenotype. Fifty-seven patients had previously received treatment for GD1 (91% enzyme replacement therapy) and 15% were splenectomized. Groups1 and 2 were not necessarily matching for all characteristics. At 6 months, 58% of Group2 patients showed medium adherence (6 < MMAS-8 < 7.75) while 21% showed high adherence (MMAS-8: 8) (mean MMAS-8: 6.7 ± 1.0); similar results were obtained in Group1 (50% showed high compliance, 35% showed medium compliance; mean MMAS-8: 6.8 ± 1.4). The mean MMAS-8 for Group1 and Group2 were 7.1 ± 1.2 (vs 7.0 ± 1.0 at baseline) and 6.5 ± 1.0, respectively, at 12 months. At 12 months, the mean NRS scores in Group1 and Group2 were 72.0 ± 18.5 and 77.3 ± 13.7 for QoL (vs. 71.7 ± 18.4 and 80.2 ± 12.4, respectively at baseline), 4.8 ± 2.6 and 3.6 ± 2.7 for fatigue (vs. 4.6 ± 2.7 and 3.6 ± 2.6, respectively at baseline) and 3.3 ± 2.7 and 2.3 ± 2.3 for pain (vs. 3.3 ± 2.7 and 2.0 ± 2.4, respectively at baseline). GD1 assessments (biological, clinical and imaging parameters) remained stable during 12 months in both groups. At the end of the study, majority (97.4%) of patients were satisfied with their treatment with eliglustat (satisfaction score over 5 out of 7). Sixty-six percent of patients (n = 41) experienced mostly mild adverse events (AE) (including four study withdrawals), of whom 27.4% (n = 17) of patients experienced eliglustat-related AEs. Treatment adherence remained stable during 12 months in both groups.

CONCLUSIONS

Eliglustat treatment compliance was good and sustained, along with overall health state, fatigue and pain levels, which was consistent with overall patients' clinical status. Eliglustat was well tolerated, and had a good safety profile, aligned with a good patient satisfaction. Our study should encourage greater use of PROs for evaluation of impact of the GD treatment on patient's symptoms and well-being.

Novel beta-glucocerebrosidase chaperone compounds identified from cell-based screening reduce pathologically accumulated glucosylsphingosine in iPS-derived neuronal cells

The beta-glucocerebrosidase (GBA1) gene encodes the lysosomal beta-glucocerebrosidase (GCase) that metabolizes the lipids glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph). Biallelic loss-of-function mutations in GBA1 such as L444P cause Gaucher disease (GD), which is the most prevalent lysosomal storage disease and is histopathologically characterized by abnormal accumulation of the GCase substrates GlcCer and GlcSph. GD with neurological symptoms is associated with severe mutations in the GBA1 gene, most of which cause impairment in the process of GCase trafficking to lysosomes. Given that recombinant GCase protein cannot cross the blood-brain barrier due to its high molecular weight, it is invaluable to develop a brain-penetrant small-molecule pharmacological chaperone as a viable therapeutic strategy to boost GCase activity in the central nervous system. Despite considerable efforts to screen potent GCase activators/chaperones, cell-free assays using recombinant GCase protein have yielded compounds with only marginal efficacy and micromolar EC50 that would not have sufficient clinical efficacy or an acceptable safety margin. Therefore, we utilized a fluorescence-labeled GCase suicide inhibitor, MDW933, to directly monitor lysosomal GCase activity and performed a cell-based screening in fibroblasts from a GD patient with homozygotic L444P mutations. Here, we identified novel compounds that increase the fluorescence signal from labeled GCase with L444P mutations in a dose-dependent manner. Secondary assays using an artificial cell-permeable lysosomal GCase substrate also demonstrated that the identified compounds augment lysosomal GCase L444P in the fibroblast. Moreover, those compounds increased the total GCase L444P protein levels, suggesting the pharmacological chaperone-like mechanism of action. To further elucidate the effect of the compounds on the endogenous GCase substrate GlcSph, we generated iPSC-derived dopaminergic neurons with a GBA1 L444P mutation that exhibit GlcSph accumulation in vitro. Importantly, the identified compounds reduce GlcSph in iPSC-derived dopaminergic neurons with a GBA1 L444P mutation, indicating that the increase in lysosomal GCase resulting from application of the compounds leads to the clearance of pathologically-accumulated GlcSph. Together, our findings pave the way for developing potent and efficacious GCase chaperone compounds as a potential therapeutic approach for neurological GD.

GBA1 Variants and Parkinson's Disease: Paving the Way for Targeted Therapy

Glucosylceramidase beta 1 (GBA1) variants have attracted enormous attention as the most promising and important genetic candidates for precision medicine in Parkinson's disease (PD). A substantial correlation between GBA1 genotypes and PD phenotypes could inform the prediction of disease progression and promote the development of a preventive intervention for individuals at a higher risk of a worse disease prognosis. Moreover, the GBA1-regulated pathway provides new perspectives on the pathogenesis of PD, such as dysregulated sphingolipid metabolism, impaired protein quality control, and disrupted endoplasmic reticulum-Golgi trafficking. These perspectives have led to the development of novel disease-modifying therapies for PD targeting the GBA1-regulated pathway by repositioning treatment strategies for Gaucher's disease. This review summarizes the current hypotheses on a mechanistic link between GBA1 variants and PD and possible therapeutic options for modulating GBA1-regulated pathways in PD patients.

Patient-reported outcomes in Gaucher's disease: a systematic review

BACKGROUND

Gaucher's disease (GD), a rare condition, represents the most common lysosomal storage disorder. The cardinal manifestations of GD are fatigue, hepatosplenomegaly, anemia, thrombocytopenia, bone pain, and bone infarction, thereby culminating in a marked deterioration of patients' quality of life (QoL). Patient-reported outcomes (PROs) offer valuable insights into the impact of GD on patients' QoL and symptoms. This systematic review aimed to identify and analyze PROs and outcome measures in GD patients.

METHODS

We systematically searched PubMed, Web of Science Core Collections, EMBASE, SCOPUS, Cochrane Library, PsycINFO, Wan Fang Data, China National Knowledge Infrastructure (CNKI), and the Chinese Biomedical Literature Database (CBM). The methodological quality of the included studies was assessed using a mixed methods assessment tool.

RESULTS

A total of 33 studies were identified, encompassing 24 distinct patient-reported outcome instruments, with the most frequently employed instrument being the SF-36. The study designs included eighteen cross-sectional studies, seven pre- and post-intervention investigations, three randomized controlled trials, two cohort studies, two qualitative inquiries, and one validation study. These studies explored diverse domains such as the QoL and cardinal symptoms (e.g., fatigue, pain, bleeding, cognition, social relationships, and psychological functioning) in patients with GD. Furthermore, significant attention was directed towards the appraisal of the therapeutic benefits of various interventions in patients with GD. A novel GD-specific instrument has also been developed, which has two applied versions: a 24-item variant for routine clinical monitoring and a 17-item form for use in clinical trials.

CONCLUSION

PROs have garnered increased attention and concern in the realm of GD. Despite this progress, it is noteworthy that the instruments used to measure PROs in GD are still predominantly generic instruments. While researchers have endeavored to develop and validate a disease-specific instrument, currently the use of this instrument is limited. Owing to several challenges, including the small number of patients, heterogeneity of the disease, and cross-regional discrepancies in study findings, GD poses substantial difficulties in the measurement of QoL and development of instruments. Consequently, patients with GD require more dependable measurement instruments that accurately reflect their QoL, efficacy of treatment, and facilitate healthcare decision-making.

Fat fraction quantification of bone marrow in the lumbar spine using the LiverLab assessment tool in healthy adult volunteers and patients with Gaucher disease

BACKGROUND

Magnetic Resonance Imaging is used for evaluation of bone in Gaucher disease (GD), but a widely available quantitative scoring method remains elusive.

AIMS

The study purpose was to assess the reproducibility of the LiverLab tool for assessing bone marrow fat fraction (FF) and determine whether it could differentiate GD patients from healthy subjects.

METHODS

Ten healthy volunteers and 18 GD patients were prospectively recruited. FF was calculated at L3, L4 and L5. GD patient bone marrow burden (BMB) score assessed by one observer. Inter and intra-rater agreement assessed with Bland-Altman data plots. Differences in FF between healthy volunteers versus GD patients and between subjects treated versus not treated assessed using two-sample t-tests. In GD patients, the relationship between FF, BMB and glucosylsphingosine was determined using the Pearson's correlation coefficient.

RESULTS

Healthy volunteer mean FF was 0.36, standard deviation (SD) 0.10 (range 0.20-0.57). Intra and inter-rater SD were both 0.02. GD patient mean FF was 0.40, SD 0.13 (range 0.09-0.57). No statistical difference was shown between healthy volunteers and GD patients (P = 0.447) or between GD patients whether on enzyme replacement therapy or not (P = 0.090). No significant correlation between mean FF and total BMB (r = -0.525, P = 0.253) or between FF and glucosylsphingosine levels (r = 0.287, P = 0.248).

CONCLUSION

Excellent reproducibility of LiverLab FF measurements across studies and observers is comparable to Dixon quantitative chemical shift imaging (QCSI). Lack of statistical difference between GD patients and controls may be explained by limited patient numbers, active treatment or mild disease severity in untreated patients.

The loss of function GBA1 c.231C > G mutation associated with Parkinson disease

Parkinson's disease (PD) is the second most common neurodegenerative disease characterized by bradykinesia, rigidity, and tremor. However, familial PD caused by single-gene mutations remain relatively rare. Herein, we described a Chinese family affected by PD, which associated with a missense heterozygous glucocerebrosidase 1 (GBA1) mutation (c.231C > G). Clinical data on the proband and her family members were collected. Brain MRI showed no difference between affected and unaffected family members. Whole-exome sequencing (WES) was performed to identify the pathogenic mutation. WES revealed that the proband carried a missense mutation (c.231C > G) in GBA1 gene, which was considered to be associated with PD in this family. Sanger sequencing and co-segregation analyses were used to validate the mutation. Bioinformatics analysis indicated that the mutation was predicted to be damaging. In vitro functional analyses were performed to investigated the mutant gene. A decrease in mRNA and protein expression was observed in HEK293T cells transfected with mutant plasmids. The GBA1 c.231C > G mutation caused a decreased GBA1 concentration and enzyme activity. In conclusion, a loss of function mutation (c.231C > G) in GBA1 was identified in a Chinese PD family and was confirmed to be pathogenic through functional studies. This study help the family members understand the disease progression and provide a new example for studying the pathogenesis of GBA1-associated Parkinson disease.

Neuronopathic Gaucher disease models reveal defects in cell growth promoted by Hippo pathway activation

Gaucher Disease (GD), the most common lysosomal disorder, arises from mutations in the GBA1 gene and is characterized by a wide spectrum of phenotypes, ranging from mild hematological and visceral involvement to severe neurological disease. Neuronopathic patients display dramatic neuronal loss and increased neuroinflammation, whose molecular basis are still unclear. Using a combination of Drosophila dGBA1b loss-of-function models and GD patient-derived iPSCs differentiated towards neuronal precursors and mature neurons we showed that different GD- tissues and neuronal cells display an impairment of growth mechanisms with an increased cell death and reduced proliferation. These phenotypes are coupled with the downregulation of several Hippo transcriptional targets, mainly involved in cells and tissue growth, and YAP exclusion from nuclei. Interestingly, Hippo knock-down in the GBA-KO flies rescues the proliferative defect, suggesting that targeting the Hippo pathway can be a promising therapeutic approach to neuronopathic GD.

Targeting the GBA1 pathway to slow Parkinson disease: Insights into clinical aspects, pathogenic mechanisms and new therapeutic avenues

The GBA1 gene encodes the lysosomal enzyme glucocerebrosidase (GCase), which is involved in sphingolipid metabolism. Biallelic variants in GBA1 cause Gaucher disease (GD), a lysosomal storage disorder characterised by loss of GCase activity and aberrant intracellular accumulation of GCase substrates. Carriers of GBA1 variants have an increased risk of developing Parkinson disease (PD), with odds ratio ranging from 2.2 to 30 according to variant severity. GBA1 variants which do not cause GD in homozygosis can also increase PD risk. Patients with PD carrying GBA1 variants show a more rapidly progressive phenotype compared to non-carriers, emphasising the need for disease modifying treatments targeting the GBA1 pathway. Several mechanisms secondary to GCase dysfunction are potentially responsible for the pathological changes leading to PD. Misfolded GCase proteins induce endoplasmic reticulum stress and subsequent unfolded protein response and impair the autophagy-lysosomal pathway. This results in α-synuclein accumulation and spread, and promotes neurodegenerative changes. Preclinical evidence also shows that products of GCase activity can promote accumulation of α-synuclein, however there is no convincing evidence of substrate accumulation in GBA1-PD brains. Altered lipid homeostasis secondary to loss of GCase activity could also contribute to PD pathology. Treatments that target the GBA1 pathway could reverse these pathological processes and halt/slow the progression of PD. These range from augmentation of GCase activity via GBA1 gene therapy, restoration of normal intracellular GCase trafficking via molecular chaperones, and substrate reduction therapy. This review discusses the pathways associated with GBA1-PD and related novel GBA1-targeted interventions for PD treatment.

The ovine Type II Gaucher disease model recapitulates aspects of human brain disease

Acute neuronopathic (type II) Gaucher disease (GD) is a devastating, untreatable neurological disorder resulting from mutations in the glucocerebrosidase gene (GBA1), with subsequent accumulation of glucosylceramide and glucosylsphingosine. Patients experience progressive decline in neurological function, with onset typically within the first three-to-six months of life and premature death before two years. Mice and drosophila with GD have been described, however little is known about the brain pathology observed in the naturally occurring ovine model of GD. We have characterised pathological changes in GD lamb brain and compared the histological findings to those in GD patient post-mortem tissue, to determine the validity of the sheep as a model of this disease. Five GD and five age-matched unaffected lamb brains were examined. We observed significant expansion of the endo/lysosomal system in GD lamb cingulate gyrus however TPP1 and cathepsin D levels were unchanged or reduced. H&E staining revealed neurons with shrunken, hypereosinophilic cytoplasm and hyperchromatic or pyknotic nuclei (red neurons) that were also shrunken and deeply Nissl stain positive. Amoeboid microglia were noted throughout GD brain. Spheroidal inclusions reactive for TOMM20, ubiquitin and most strikingly, p-Tau were observed in many brain regions in GD lamb brain, potentially indicating disturbed axonal trafficking. Our findings suggest that the ovine model of GD exhibits similar pathological changes to human, mouse, and drosophila type II GD brain, and represents a model suitable for evaluating therapeutic intervention, particularly in utero-targeted approaches.

Post-translational proteomics platform identifies neurite outgrowth impairments in Parkinson's disease GBA-N370S dopamine neurons

Variants at the GBA locus, encoding glucocerebrosidase, are the strongest common genetic risk factor for Parkinson's disease (PD). To understand GBA-related disease mechanisms, we use a multi-part-enrichment proteomics and post-translational modification (PTM) workflow, identifying large numbers of dysregulated proteins and PTMs in heterozygous GBA-N370S PD patient induced pluripotent stem cell (iPSC) dopamine neurons. Alterations in glycosylation status show disturbances in the autophagy-lysosomal pathway, which concur with upstream perturbations in mammalian target of rapamycin (mTOR) activation in GBA-PD neurons. Several native and modified proteins encoded by PD-associated genes are dysregulated in GBA-PD neurons. Integrated pathway analysis reveals impaired neuritogenesis in GBA-PD neurons and identify tau as a key pathway mediator. Functional assays confirm neurite outgrowth deficits and identify impaired mitochondrial movement in GBA-PD neurons. Furthermore, pharmacological rescue of glucocerebrosidase activity in GBA-PD neurons improves the neurite outgrowth deficit. Overall, this study demonstrates the potential of PTMomics to elucidate neurodegeneration-associated pathways and potential drug targets in complex disease models.

Direct activation of microglia by β-glucosylceramide causes phagocytosis of neurons that exacerbates Gaucher disease

Gaucher disease (GD) is the most common lysosomal storage disease caused by recessive mutations in the degrading enzyme of β-glucosylceramide (β-GlcCer). However, it remains unclear how β-GlcCer causes severe neuronopathic symptoms, which are not fully treated by current therapies. We herein found that β-GlcCer accumulating in GD activated microglia through macrophage-inducible C-type lectin (Mincle) to induce phagocytosis of living neurons, which exacerbated Gaucher symptoms. This process was augmented by tumor necrosis factor (TNF) secreted from activated microglia that sensitized neurons for phagocytosis. This characteristic pathology was also observed in human neuronopathic GD. Blockade of these pathways in mice with a combination of FDA-approved drugs, minocycline (microglia activation inhibitor) and etanercept (TNF blocker), effectively protected neurons and ameliorated neuronopathic symptoms. In this study, we propose that limiting unrestrained microglia activation using drug repurposing provides a quickly applicable therapeutic option for fatal neuronopathic GD.

Pyrazole Ureas as Low Dose, CNS Penetrant Glucosylceramide Synthase Inhibitors for the Treatment of Parkinson's Disease

Parkinson's disease is the second most prevalent progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra. Loss-of-function mutations in GBA, the gene that encodes for the lysosomal enzyme glucosylcerebrosidase, are a major genetic risk factor for the development of Parkinson's disease potentially through the accumulation of glucosylceramide and glucosylsphingosine in the CNS. A therapeutic strategy to reduce glycosphingolipid accumulation in the CNS would entail inhibition of the enzyme responsible for their synthesis, glucosylceramide synthase (GCS). Herein, we report the optimization of a bicyclic pyrazole amide GCS inhibitor discovered through HTS to low dose, oral, CNS penetrant, bicyclic pyrazole urea GCSi's with in vivo activity in mouse models and ex vivo activity in iPSC neuronal models of synucleinopathy and lysosomal dysfunction. This was accomplished through the judicious use of parallel medicinal chemistry, direct-to-biology screening, physics-based rationalization of transporter profiles, pharmacophore modeling, and use a novel metric: volume ligand efficiency.

Similarities and differences between Gaucher disease and acid sphingomyelinase deficiency: An algorithm to support the diagnosis

Lysosomal storage disorders are a group of inborn errors of metabolism due to defects in proteins crucial for lysosomal function. Gaucher disease is the most common autosomal recessive lysosomal storage disorder due to mutations in the GBA1 gene, resulting in the lysosomal deficiency of glucocerebrosidase activity. Gaucher disease is characterized by the toxic accumulation of glucosylceramide in the reticuloendothelial system. Acid sphingomyelinase deficiency (ASMD), previously known as Niemann Pick A/B disease, is also an autosomal recessive lysosomal storage disorder due to mutations in the SMPD1 gene, which result in acid sphingomyelinase deficiency and the accumulation of sphingomyelin in mononuclear phagocytic system and hepatocytes. The phenotypic expression of Gaucher disease type 1 (GD1), the most common type, and chronic visceral ASMD may overlap for several signs or symptoms. Splenomegaly is detectable in approximately 90% of the patients in both conditions; however, since GD1 is more frequent than ASMD, clinicians are more prone to suspect it, often neglecting the diagnosis of ASMD. Based on previous experience, a group of experts in the clinical and laboratory diagnosis, management, and treatment of lysosomal storage disorders developed an algorithm for both GD1 and ASMD to support physicians, including primary care providers, internists, and specialists (e.g., hepatologists, hematologists, and pulmonologists) to suspect and differentiate GD1 and ASMD and to provide the appropriate referral.

Screening for potential undiagnosed Gaucher disease patients: Utilisation of the Gaucher earlier diagnosis consensus point-scoring system (GED-C PSS) in conjunction with electronic health record data, tissue specimens, and small nucleotide polymorphism (SNP) genotype data available in Finnish biobanks

Background

Autosomal recessive Gaucher disease (GD) is likely underdiagnosed in many countries. Because the number of diagnosed GD patients in Finland is relatively low, and the true prevalence is currently not known, it was hypothesized that undiagnosed GD patients may exist in Finland. Our previous study demonstrated the applicability of Gaucher Earlier Diagnosis Consensus point-scoring system (GED-C PSS; Mehta et al., 2019) and Finnish biobank data and specimens in the automated point scoring of large populations. An indicative point-score range for Finnish GD patients was determined, but undiagnosed patients were not identified partly due to high number of high-score subjects in combination with a lack of suitable samples for diagnostics in the assessed biobank population. The current study extended the screening to another biobank and evaluated the feasibility of utilising the automated GED-C PSS in conjunction with small nucleotide polymorphism (SNP) chip genotype data from the FinnGen study of biobank sample donors in the identification of undiagnosed GD patients in Finland. Furthermore, the applicability of FFPE tissues and DNA restoration in the next-generation sequencing (NGS) of the GBA gene were tested.

Methods

Previously diagnosed Finnish GD patients eligible to the study, and up to 45,100 sample donors in Helsinki Biobank (HBB) were point scored. The GED-C point scoring, adjusted to local data, was automated, but also partly manually verified for GD patients. The SNP chip genotype data for rare GBA variants was visually assessed. FFPE tissues of GD patients were obtained from HBB and Biobank Borealis of Northern Finland (BB).

Results

Three previously diagnosed GD patients and one patient previously treated for GD-related features were included. A genetic diagnosis was confirmed for the patient treated for GD-related features. The GED-C point score of the GD patients was 12.5–22.5 in the current study. The score in eight Finnish GD patients of the previous and the current study is thus 6–22.5 points per patient. In the automated point scoring of the HBB subpopulation (N ≈ 45,100), the overall scores ranged from 0 to 17.5, with 0.77% (346/45,100) of the subjects having ≥10 points. The analysis of SNP chip genotype data was able to identify the diagnosed GD patients, but potential undiagnosed patients with the GED-C score and/or the GBA genotype indicative of GD were not discovered. Restoration of the FFPE tissue DNA improved the quality of the GBA NGS, and pathogenic GBA variants were confirmed in five out of six unrestored and in all four restored FFPE DNA samples.

Discussion

These findings imply that the prevalence of diagnosed patients (~1:325,000) may indeed correspond the true prevalence of GD in Finland. The SNP chip genotype data is a valuable tool that complements the screening with the GED-C PSS, especially if the genotyping pipeline is tuned for rare variants. These proof-of-concept biobank tools can be adapted to other rare genetic diseases.

Hemostatic Abnormalities in Gaucher Disease: Mechanisms and Clinical Implications

Gaucher disease (GD) is a rare inherited lysosomal metabolism disorder, characterized by an accumulation into lysosomes of reticuloendothelial cells, especially in the bone marrow, spleen, and liver of β-glucosylceramide and glucosyl sphingosine, which is its deacylated product. Impaired storage is responsible for a chronic inflammatory state at the sites of accumulation and together represents the pathophysiological cause of GD. GD is a progressive, multi-organ chronic disorder. Type 1 GD is the most prevalent form, with heterogeneous multisystem involvement and different severity of symptoms at any age. Hematological involvement is consistent, and a bleeding tendency is frequent, particularly at diagnosis. Several coagulation and primary hemostasis abnormalities are observed in GD. Bleeding manifestations are rarely severe and usually mucocutaneous. Post-operative, delivery, and post-partum hemorrhages are also common. Thrombocytopenia, platelet function defects, and clotting abnormalities, alone or variably associated, contribute to increase the risk of bleeding in GD. Enzyme replacement therapy (ERT) or substrate reduction therapy (SRT) are the two specific available treatments effective in improving typical hematological symptoms and abnormalities, including those of hemostasis. However, the use of medication to potentiate hemostasis may be also useful in defined clinical situations: recent starting of ERT/SRT, surgery, delivery, and life-threatening bleeding.

A multifaceted evaluation of microgliosis and differential cellular dysregulation of mammalian target of rapamycin signaling in neuronopathic Gaucher disease

Neuronopathic Gaucher disease (nGD) is an inherited neurodegenerative disease caused by mutations in GBA1 gene and is associated with premature death. Neuroinflammation plays a critical role in disease pathogenesis which is characterized by microgliosis, reactive astrocytosis, and neuron loss, although molecular mechanisms leading to neuroinflammation are not well-understood. In this report, we developed a convenient tool to quantify microglia proliferation and activation independently and uncovered abnormal proliferation of microglia (∼2-fold) in an adult genetic nGD model. The nGD-associated pattern of inflammatory mediators pertinent to microglia phenotypes was determined, showing a unique signature favoring pro-inflammatory chemokines and cytokines. Moreover, highly polarized (up or down) dysregulations of mTORC1 signaling with varying lysosome dysfunctions (numbers and volume) were observed among three major cell types of nGD brain. Specifically, hyperactive mTORC1 signaling was detected in all disease-associated microglia (Iba1^high) with concurrent increase in lysosome function. Conversely, the reduction of neurons presenting high mTORC1 activity was implicated (including Purkinje-like cells) which was accompanied by inconsistent changes of lysosome function in nGD mice. Undetectable levels of mTORC1 activity and low Lamp1 puncta were noticed in astrocytes of both diseased and normal mice, suggesting a minor involvement of mTORC1 pathway and lysosome function in disease-associated astrocytes. These findings highlight the differences and complexity of molecular mechanisms that are involved within various cell types of the brain. The quantifiable parameters established and nGD-associated pattern of neuroinflammatory mediators identified would facilitate the efficacy evaluation on microgliosis and further discovery of novel therapeutic target(s) in treating neuronopathic Gaucher disease.

Glucocerebrosidase mutations and Parkinson disease

The discovery of glucocerebrosidase (GBA1) mutations as the greatest numerical genetic risk factor for the development of Parkinson disease (PD) resulted in a paradigm shift within the research landscape. Efforts to elucidate the mechanisms behind GBA1-associated PD have highlighted shared pathways in idiopathic PD including the loss and gain-of-function hypotheses, endoplasmic reticulum stress, lipid metabolism, neuroinflammation, mitochondrial dysfunction and altered autophagy-lysosomal pathway responsible for degradation of aggregated and misfolded a-synuclein. GBA1-associated PD exhibits subtle differences in phenotype and disease progression compared to idiopathic counterparts notably an earlier age of onset, faster motor decline and greater frequency of non-motor symptoms (which also constitute a significant aspect of the prodromal phase of the disease). GBA1-targeted therapies have been developed and are being investigated in clinical trials. The most notable are Ambroxol, a small molecule chaperone, and Venglustat, a blood-brain-barrier-penetrant substrate reduction therapy agent. It is imperative that further studies clarify the aetiology of GBA1-associated PD, enabling the development of a greater abundance of targeted therapies in this new era of precision medicine.

Genetic variations in GBA1 and LRRK2 genes: Biochemical and clinical consequences in Parkinson disease

Variants in the GBA1 and LRRK2 genes are the most common genetic risk factors associated with Parkinson disease (PD). Both genes are associated with lysosomal and autophagic pathways, with the GBA1 gene encoding for the lysosomal enzyme, glucocerebrosidase (GCase) and the LRRK2 gene encoding for the leucine-rich repeat kinase 2 enzyme. GBA1-associated PD is characterized by earlier age at onset and more severe non-motor symptoms compared to sporadic PD. Mutations in the GBA1 gene can be stratified into severe, mild and risk variants depending on the clinical presentation of disease. Both a loss- and gain- of function hypothesis has been proposed for GBA1 variants and the functional consequences associated with each variant is often linked to mutation severity. On the other hand, LRRK2-associated PD is similar to sporadic PD, but with a more benign disease course. Mutations in the LRRK2 gene occur in several structural domains and affect phosphorylation of GTPases. Biochemical studies suggest a possible convergence of GBA1 and LRRK2 pathways, with double mutant carriers showing a milder phenotype compared to GBA1-associated PD. This review compares GBA1 and LRRK2-associated PD, and highlights possible genotype-phenotype associations for GBA1 and LRRK2 separately, based on biochemical consequences of single variants.

Evaluation of the Nutritional Status of Gaucher Disease Type I Patients under Enzyme Replacement Treatment

(1) Background: Gaucher disease (GD) is a rare lysosomal storage disease. The few studies analyzing Resting Energy Expenditure (REE) in GD involved mainly untreated patients and supported a hypermetabolic condition possibly due to the associated inflammatory state. Definitive conclusions could not be drawn also because of the heterogeneity and the small size of the samples investigated. In order to expand current knowledge concerning, in particular the condition of patients under Enzyme Replacement Therapy (ERT), we evaluated the nutritional status of a relatively large sample of GD patients followed at Federico II University Hospital in Naples, Italy. (2) Methods: The study, having a cross-sectional design and involving 26 patients on ERT, included routine biochemical analyses, bioelectrical impedance analysis, indirect calorimetry, and administration of food frequency and physical activity questionnaires. The results in GD patients were compared with those from an appropriate control group. (3) Results: GD patients had normal biochemical parameters in 80% of cases, except for HDL-cholesterol, consumed a hyper-lipidic diet, and had a 60% prevalence of overweight/obesity. Body composition did not differ between patients and controls; however, measured REE was significantly lower than predicted and was reduced in comparison with the healthy controls. (4) Conclusions: This study provided novel elements to the present knowledge about REE and the nutritional status of GD patients under ERT. Its results warrant confirmation in even larger GD population samples and a more in-depth investigation of the long-term effects of treatment superimposed on the basic pathophysiological disease condition.

A Rare Pitfall in Bone Mineral Densitometry: Gaucher Disease

ABSTRACT

We report a rare case of type 3 Gaucher disease presenting with calcified mesenteric lymph nodes that interfere with bone mineral densitometric measurements.

Early diagnosis of Gaucher disease in Korean patients with unexplained splenomegaly: a multicenter observational study

Background

Gaucher disease (GD) is an autosomal recessive disorder characterized by excessive accumulation of glucosylceramide in multiple organs. This study was performed to determine the detection rate of GD in a selected patient population with unexplained splenomegaly in Korea.

Methods

This was a multicenter, observational study conducted at 18 sites in Korea between December 2016 and February 2020. Adult patients with unexplained splenomegaly were enrolled and tested for β-glucosidase enzyme activity on dried blood spots (DBS) and in peripheral blood leukocytes. Mutation analysis was performed if the test was positive or indeterminate for the enzyme assay. The primary endpoint was the percentage of patients with GD in patients with unexplained splenomegaly.

Results

A total of 352 patients were enrolled in this study (male patients, 199; mean age, 48.42 yr). Amongst them, 14.77% of patients had concomitant hepatomegaly. The most common sign related to GD was splenomegaly (100%), followed by thrombocytopenia (44.32%) and, anemia (40.91%). The β-glucosidase activity assay on DBS and peripheral leukocytes showed abnormal results in sixteen and six patients, respectively. Eight patients were tested for the mutation, seven of whom were negative and one patient showed a positive mutation analysis result. One female patient who presented with splenomegaly and thrombocytopenia was diagnosed with type 1 GD. The detection rate of GD was 0.2841% (exact 95% CI, 0.0072‒1.5726).

Conclusion

The detection rate of GD in probable high-risk patients in Korea was lower than expected. However, the role of hemato-oncologists is still important in the diagnosis of GD.

Exosome- and extracellular vesicle-based approaches for the treatment of lysosomal storage disorders

Cell-generated extracellular vesicles (EVs) are being engineered as biologically-inspired vehicles for targeted delivery of therapeutic agents to treat difficult-to-manage human diseases, including lysosomal storage disorders (LSDs). Engineered EVs offer distinct advantages for targeted delivery of therapeutics compared to existing synthetic and semi-synthetic nanoscale systems, for example with regard to their biocompatibility, circulation lifetime, efficiencies in delivery of drugs and biologics to target cells, and clearance from the body. Here, we review literature related to the design and preparation of EVs as therapeutic carriers for targeted delivery and therapy of drugs and biologics with a focus on LSDs. First, we introduce the basic pathophysiology of LDSs and summarize current approaches to diagnose and treat LSDs. Second, we will provide specific details about EVs, including subtypes, biogenesis, biological properties and their potential to treat LSDs. Third, we review state-of-the-art approaches to engineer EVs for treatments of LSDs. Finally, we summarize explorative basic research and applied applications of engineered EVs for LSDs, and highlight current challenges, and new directions in developing EV-based therapies and their potential impact on clinical medicine.

Phagocytosis of Erythrocytes from Gaucher Patients Induces Phenotypic Modifications in Macrophages, Driving Them toward Gaucher Cells

Gaucher disease (GD) is caused by glucocerebrosidase deficiency leading to the accumulation of sphingolipids in macrophages named “Gaucher’s Cells”. These cells are characterized by deregulated expression of cell surface markers, abnormal secretion of inflammatory cytokines, and iron sequestration. These cells are known to infiltrate tissues resulting in hematological manifestations, splenomegaly, and bone diseases. We have already demonstrated that Gaucher red blood cells exhibit altered properties suggesting their key role in GD clinical manifestations. We hypothesized that Gaucher’s erythrocytes could be prone to premature destruction by macrophages contributing to the formation of altered macrophages and Gaucher-like cells. We conducted in vitro experiments of erythrophagocytosis using erythrocytes from Gaucher’s patients or healthy donors. Our results showed an enhanced erythrophagocytosis of Gaucher red blood cells compared to healthy red blood cells, which is related to erythrocyte sphingolipids overload and reduced deformability. Importantly, we showed elevated expression of the antigen-presenting molecules CD1d and MHC-II and of the iron-regulator hepcidin in macrophages, as well as enhanced secretion of the pro-inflammatory cytokine IL-1β after phagocytosis of GD erythrocytes. These results strongly suggested that erythrophagocytosis in GD contribute to phenotypic modifications in macrophages. This present study shows that erythrocytes-macrophages interactions may be crucial in GD pathophysiology and pathogenesis.

The role of lysosomal cathepsins in neurodegeneration: Mechanistic insights, diagnostic potential and therapeutic approaches

Lysosomes are ubiquitous organelles with a fundamental role in maintaining cellular homeostasis by mediating degradation and recycling processes. Cathepsins are the most abundant lysosomal hydrolyses and are responsible for the bulk degradation of various substrates. A correct autophagic function is essential for neuronal survival, as most neurons are post-mitotic and thus susceptible to accumulate cellular components. Increasing evidence suggests a crucial role of the lysosome in neurodegeneration as a key regulator of aggregation-prone and disease-associated proteins, such as α-synuclein, β-amyloid and huntingtin. Particularly, alterations in lysosomal cathepsins CTSD, CTSB and CTSL can contribute to the pathogenesis of neurodegenerative diseases as seen for neuronal ceroid lipofuscinosis, synucleinopathies (Parkinson's disease, Dementia with Lewy Body and Multiple System Atrophy) as well as Alzheimer's and Huntington's disease. In this review, we provide an overview of recent evidence implicating CTSD, CTSB and CTSL in neurodegeneration, with a special focus on the role of these enzymes in α-synuclein metabolism. In addition, we summarize the potential role of lysosomal cathepsins as clinical biomarkers in neurodegenerative diseases and discuss potential therapeutic approaches by targeting lysosomal function.