Immunoglobulin and free light chain abnormalities in Gaucher disease type I: data from an adult cohort of 63 patients and review of the literature

A Brazilian Rare-Disease Center's Experience with Glucosylsphingosine (lyso-Gb1) in Patients with Gaucher Disease: Exploring a Novel Correlation with IgG Levels in Plasma and a Biomarker Measurement in CSF

Gaucher disease (GD, OMIM 230800) is one of the most common lysosomal disorders, being caused by the deficient activity of the enzyme acid β-glucocerebrosidase (Gcase). Three clinical forms of Gaucher's disease (GD) are classified based on neurological involvement. Type 1 (GD1) is non-neuronopathic, while types 2 (GD2) and 3 (GD3) are neuronopathic forms. Gcase catalyzes the conversion of glucosylceramide (GlcCer) into ceramide and glucose. As GlcCer accumulates in lysosomal macrophages, it undergoes deacylation to become glycosylsphingosine (lyso-Gb1), which has shown to be a useful and reliable biomarker for the diagnosis and monitoring of treated and untreated patients with GD. Multiple myeloma (MM) is one of the leading causes of cancer-related death among patients with GD and monoclonal gammopathy of undetermined significance (MGUS) is a non-neoplastic condition that can be a telltale sign of a B clonal proliferation caused by the chronic activation of B cells. This study aimed to quantify Lyso-Gb1 levels in dried blood spots (DBS) and cerebrospinal fluid (CSF) as biomarkers for Gaucher disease (GD) and discuss the association of this biomarker with other clinical parameters. This is a mixed-methods study incorporating both cross-sectional and longitudinal elements within a cohort design with a convenience-sampling strategy. Data collection took place from January 2012 to March 2023. Lyso-Gb1 extraction from DBS involved the use of a methanol-acetonitrile-water mixture, followed by incubation and centrifugation. Analysis was performed using UPLC-MS/MS with MassLynx software version 4.2 and the control group for the DBS measurements included general newborns. CSF Lyso-Gb1 was extracted using ethyl acetate, analyzed by UPLC-MS/MS with a calibration curve, and expressed in pmol/L. Lysosomal activity in CSF was assessed by measuring chitotriosidase (Cht), and other lysosomal enzyme activities were assessed as previously described in the literature. Patients with metachromatic leukodystrophy (MLD) were used as controls. Thirty-two treated patients (twenty-nine GD1 and three GD3, all on ERT except for one GD type on SRT with eliglustat) and three untreated patients (one GD1, one GD2, and one GD3) were included. When analyzing only the treated GD1 group, a significant correlation was found between lyso-Gb1 and age (rho = -0.447, p = 0.001), ChT, and IgG levels (rho = 0.73, p < 0.001; and rho = 0.36, p = 0.03, respectively). Five GD1 patients (three females, mean age 40 years) also had their CSF collected and analyzed. The average measurement of lyso-Gb1 in CSF was 94 pmol/L (range: 57.1-157.9 pmol/L) versus <6.2 pmol/L in the control group (MLD). This is the first time, to the best of our knowledge, that lyso-Gb1 has been associated with IgG levels. While this finding reflects a risk for MGUS or MM and not only chronic plasma B-cell activation, it still requires further studies. Moreover, the analysis of CSF lyso-Gb1 levels in GD1 patients was demonstrated to be significantly higher than the control group. This raises the hypothesis that CSF lyso-Gb1 may serve as a valuable indicator for neurological involvement in GD, providing insights into the potential implications for neurological manifestations in GD, including GD1. The correlation between lyso-Gb1 and ChT levels in treated GD1 patients further underscores the interconnectedness of lysosomal markers and their relevance in monitoring.

The Complexities of Diagnosis with Co-Existing Gaucher Disease and Hemato-Oncology-A Case Report and Review of the Literature

Hematological abnormalities are the most common early symptoms of Gaucher disease (GD), with an increased risk of hematopoietic system malignancies reported in patients with GD. GD may be associated with monoclonal and polyclonal gammopathies; however, the mechanism of association of GD with multiple myeloma (MM) remains uncertain. Enzyme replacement therapy (ERT) has been shown to improve patients' cytopenia and it seems to facilitate anti-myeloma therapy in patients with co-occurring GD and MM. Although it is necessary to demonstrate the deficiency of enzymatic activity, as well as using genetic tests to finally diagnose GD, due to changes in the blood count image, bone marrow biopsy is still a frequent element of the GD diagnosis procedure. The diagnosis of GD is often delayed, mainly due to the heterogeneity of the histopathological picture of bone marrow biopsy or overlapping hematological abnormalities. Unrecognized and untreated GD worsens the response of a patient with an oncological disease to targeted treatment. We present a literature review, inspired by the case of a Caucasian patient initially diagnosed with MM and later confirmed with comorbid GD type 1 (GD1). We would like to point out the problem of underdiagnosis and delay in patients with GD.

Glucosylsphingosine (Lyso-Gb1) as a reliable biomarker in Gaucher disease: a narrative review

BACKGROUND

Gaucher disease (GD) is a rare, inherited, autosomal recessive disorder caused by a deficiency of the lysosomal enzyme, acid β-glucosidase. Its diagnosis is achieved via measurements of acid β-glucosidase activity in either fresh peripheral blood leukocytes or dried blood spots, and confirmed by identifying characteristic mutations in the GBA1 gene. Currently, several biomarkers are available for disease monitoring. Chitotriosidase has been used over the last 20 years to assess the severity of GD, but lacks specificity in GD patients. Conversely, the deacylated form of glucosylceramide, glucosylsphingosine (also known as lyso-Gb1), represents a more reliable biomarker characterized by its high sensitivity and specificity in GD.

MAIN TEXT

Herein, we review the current literature on lyso-Gb1 and describe evidence supporting its usefulness as a biomarker for diagnosing and evaluating disease severity in GD and monitoring treatment efficacy.

CONCLUSION

Lyso-Gb1 is the most promising biomarker of GD, as demonstrated by its reliability in reflecting disease burden and monitoring treatment response. Furthermore, lyso-Gb1 may play an important role in the onset of monoclonal gammopathy of uncertain significance, multiple myeloma, and Parkinson's disease in GD patients.

Cancer risk and gammopathies in 2123 adults with Gaucher disease type 1 in the International Gaucher Group Gaucher Registry

There are numerous reports of cancers in Gaucher disease (GD) from mostly small single-center studies; however, precise risk estimates and cancer types involved have not been delineated. We conducted a study involving 2123 patients with GD type 1 (GD1) to assess the incidence of hematological malignancies, gammopathies, and solid tumors in an international observational study, the International Cooperative Gaucher Group Gaucher Registry (Clinicaltrials.gov: NCT00358943). Risk for cancer overall and for each type of malignancy was compared to the United States (US) population using the Surveillance, Epidemiology, and End Results database. Natural history of gammopathy was determined through assessing the progression from a diagnosis of monoclonal gammopathy of unknown significance (MGUS) to multiple myeloma (MM). Risk for hematological malignancies was more than four times higher than expected compared to the general population: non-Hodgkin lymphoma was approximately three times higher; MM was approximately nine times higher. Age-specific incidence rates of MGUS were unexpectedly high among younger patients. The 10-year cumulative incidence of MM after diagnosis of MGUS was 7.9%, comparable to the general population. Compared to the general US population, GD1 patients were at higher risk for solid malignancies of liver (2.9 times), kidney (2.8 times), melanoma (2.5 times), and breast (1.4 times). Colorectal, prostate, and lung cancer risks were lower than expected. These findings help advance care of patients with GD1 by supporting recommendations for individualized monitoring for malignancies and antecedents such as MGUS for MM and provoke important questions of the role of glucosylceramide and related sphingolipids in cancer biology.

Biological Variation in Peripheral Inflammation and Oxidative Stress Biomarkers in Individuals with Gaucher Disease

The lack of reliable biomarkers is a significant challenge impeding progress in orphan drug development. For appropriate interpretation of intervention-based results or for evaluating candidate biomarkers, other things being equal, lower variability in biomarker measurement would be helpful. However, variability in rare disease biomarkers is often poorly understood. Type 1 Gaucher disease (GD1) is one such rare lysosomal storage disorder. Oxidative stress and inflammation have been linked to the pathophysiology of GD1 and validated measures of these processes can provide predictive value for treatment success or disease progression. This study was undertaken to investigate and compare the extent of longitudinal biological variation over a three-month period for various blood-based oxidative stress and inflammation markers in participants with GD1 on stable standard-of-care therapy (N = 13), treatment-naïve participants with GD1 (N = 5), and in age- and gender-matched healthy volunteers (N = 18). We utilized Bland–Altman plots for visual comparison of the biological variability among the three measurements. We also report group-wise means and the percentage of coefficient of variation (%CV) for 15 biomarkers. Qualitatively, we show specific markers (IL-1Ra, IL-8, and MIP-1b) to be consistently altered in GD1, irrespective of therapy status, highlighting the need for adjunctive therapies that can target and modulate these biomarkers. This information can help guide the selection of candidate biomarkers for future intervention-based studies in GD1 patients.

Role of Sphingolipids in Multiple Myeloma Progression, Drug Resistance, and Their Potential as Therapeutic Targets

Multiple myeloma (MM) is an incapacitating hematological malignancy characterized by accumulation of cancerous plasma cells in the bone marrow (BM) and production of an abnormal monoclonal protein (M-protein). The BM microenvironment has a key role in myeloma development by facilitating the growth of the aberrant plasma cells, which eventually interfere with the homeostasis of the bone cells, exacerbating osteolysis and inhibiting osteoblast differentiation. Recent recognition that metabolic reprograming has a major role in tumor growth and adaptation to specific changes in the microenvironmental niche have led to consideration of the role of sphingolipids and the enzymes that control their biosynthesis and degradation as critical mediators of cancer since these bioactive lipids have been directly linked to the control of cell growth, proliferation, and apoptosis, among other cellular functions. In this review, we present the recent progress of the research investigating the biological implications of sphingolipid metabolism alterations in the regulation of myeloma development and its progression from the pre-malignant stage and discuss the roles of sphingolipids in in MM migration and adhesion, survival and proliferation, as well as angiogenesis and invasion. We introduce the current knowledge regarding the role of sphingolipids as mediators of the immune response and drug-resistance in MM and tackle the new developments suggesting the manipulation of the sphingolipid network as a novel therapeutic direction for MM.

Enzyme replacement therapy leading to improvement in myeloma indices in a patient with concomitant Gaucher disease

Patients with Gaucher disease (GD) have been shown previously to carry an increased risk for cancer, most commonly multiple myeloma (MM). It is currently unknown whether treatment for GD has an effect on the prevention or amelioration of MM. We present the case of a 41-year-old patient simultaneously diagnosed with GD and smouldering MM. Enzyme replacement therapy with Velaglucerase-alfa significantly improved myeloma indices.

Fabry disease associated with multiple myeloma: a case report

Fabry disease (FD) is an X-linked genetic lysosomal disorder caused by alpha-galactosidase A (GLA) deficiency. Multiple myeloma (MM) predominately affects older adults, which ranks as the second commonest hematological malignancy. Their overlap has rarely been reported. We present a case of the coexistence of FD and MM in a patient. We report the case of a 68-year-old woman who was referred to our hospital for the evaluation of thoracic spine tumor with bone destruction. On admission, her serum creatinine (Cr) level was elevated to 12.70 mg/dL from the baseline value of 0.91 mg/dL. Bone marrow aspiration revealed MM. Renal biopsy showed myeloma cast nephropathy, which was the primary cause of acute kidney injury. Renal pathology also showed podocyte swelling and tubule myeloid bodies in a mosaic pattern compatible with female FD. Consequently, the patient was diagnosed as FD based on the germ line mutation in GLA. The patient was treated with bortezomib and dexamethasone therapy, which significantly improved the renal function. This is the second case demonstrating a potential pathogenic relationship between FD and MM. Since FD is one of the few genetic diseases for which there are therapeutic agents with fewer side effects, diagnostic value of FD is high. If an MM patient has multiple organ abnormalities or any familial history, the physician should suspect FD.

Downregulation of B regulatory cells and upregulation of T helper 1 cells in children with Gaucher disease undergoing enzyme replacement therapy

Gaucher disease (GD) involves a broad spectrum of immunological cells, including T helper (Th) cells and regulatory B cells (Bregs), which function to resolve the immune response and inhibit excessive inflammation. This study aimed to explore T helper cells, B cells, and Bregs in GD children undergoing enzyme replacement therapy (ERT). Our study included 20 GD patients; six patients were categorized as type 1 and 14 as type 3 GD. All patients were on regular ERT. Twenty healthy children were enrolled as controls. All patients and controls were subjected to complete blood analysis, abdominal ultrasound, and flow cytometric detection of T helper cells, B cells, and Bregs. Despite undergoing ERT, CD4+ T helper lymphocytes and Bregs were still significantly lower in patients with GD compared with the controls. Th1 and B cells were more in the patients than in the healthy controls. Lower levels of Bregs were found in type 3, compared with type 1 patients. Increased platelet count was directly associated with increased levels of Bregs and lower levels of B cells. Elevated children's height was also accompanied by decreasing levels of Th1. Our results propose that ERT in GD is associated with partial improvement in immune status, and long-term ERT might be needed for the restoration of the desired immune response levels. Levels of Bregs and Th1 can be employed for monitoring improvement of immune status in GD patients undergoing ERT.

Hematological manifestations and complications of Gaucher disease

Introduction: Gaucher disease (GD), although pan-ethnic and rare (common in Ashkenazi Jews), is of great importance to hematologists both for diagnosis and management. The need for increased awareness of GD is that delayed diagnosis may lead to preventable irreversible complications (mainly skeletal) or unnecessary invasive procedures (e.g. bone marrow biopsy), and the birth of another affected sibling due to lack of genetic consulting.Areas covered: The review outlines the common hematological manifestations of GD, including splenomegaly, thrombocytopenia, and anemia. Other hematological manifestations such as coagulation abnormalities, platelet dysfunction, gammopathy, and other hematological malignancies associated with GD are also discussed. Current and future treatment modalities are delineated, including enzyme replacement and substrate reduction therapy, pharmacological chaperon, and gene therapy. A literature search was conducted to identify original research articles relevant to hematology manifestations and GD published before November 2020.Expert opinion: Patients with GD should be ideally followed and treated in a center of excellence where the GD expert benefits from experienced consultants in relevant disciplines. Due to the availability of several very expensive treatment options, it is important to have an unbiased expert who can select the most suitable management for the individual patients (including withholding prescription in asymptomatic patients).

Outcomes of screening for gammopathies in children and adults with Gaucher disease type 1 in a cohort from Brazil and the United States

Multiple myeloma is the most common hematological malignancy in Gaucher disease type 1 (GD1). There is a lack of outcome data and consensus regarding screening of gammopathies. This study explores utility of screening in Porto Alegre, Brazil, and Cincinnati, Ohio. A retrospective analysis of clinical information and laboratory data from GD1 patients was performed. Over 19 years, 68 individuals with GD1 (31 males, 37 females) underwent screening, and 20 (29.4%) had abnormalities. Twelve (17.6%) had polyclonal gammopathy (mean age 24.2 years, p = .02), seven (10%) had monoclonal gammopathy of uncertain significance (MGUS; mean age 52.7 years, p = .009). One had multiple myeloma (age 61 years). Risk factors for MGUS included male gender (p = .05), p.N409S allele (p = .032). MGUS developed in six of 62 treated and two of four untreated individuals. Of those with MGUS receiving treatment, four were on enzyme replacement therapy (ERT) and one on substrate reduction therapy (SRT). Gammopathy normalized in 13 treated individuals (10 polyclonal, three MGUS) and remained abnormal in two treated individuals (two polyclonal, two MGUS). Gammopathy relapse was seen in one individual with MGUS and three with polyclonal gammopathy. This study describes screening for gammopathies and identifies risk factors in individuals with GD1.

Identification of risk features for complication in Gaucher's disease patients: a machine learning analysis of the Spanish registry of Gaucher disease

BACKGROUND

Since enzyme replacement therapy for Gaucher disease (MIM#230800) has become available, both awareness of and the natural history of the disease have changed. However, there remain unmet needs such as the identification of patients at risk of developing bone crisis during therapy and late complications such as cancer or parkinsonism. The Spanish Gaucher Disease Registry has worked since 1993 to compile demographic, clinical, genetic, analytical, imaging and follow-up data from more than 400 patients. The aims of this study were to discover correlations between patients' characteristics at diagnosis and to identify risk features for the development of late complications; for this a machine learning approach involving correlation networks and decision trees analyses was applied.

RESULTS

A total of 358 patients, 340 type 1 Gaucher disease and 18 type 3 cases were selected. 18% were splenectomyzed and 39% had advanced bone disease. 81% of cases carried heterozygous genotype. 47% of them were diagnosed before the year 2000. Mean age at diagnosis and therapy were 28 and 31.5 years old (y.o.) respectively. 4% developed monoclonal gammopathy undetermined significance or Parkinson Disease, 6% cancer, and 10% died before this study. Previous splenectomy correlates with the development of skeletal complications and severe bone disease (p = 0.005); serum levels of IgA, delayed age at start therapy (> 9.5 y.o. since diagnosis) also correlates with severe bone disease at diagnosis and with the incidence of bone crisis during therapy. High IgG (> 1750 mg/dL) levels and age over 60 y.o. at diagnosis were found to be related with the development of cancer. When modelling the decision tree, patients with a delayed diagnosis and therapy were the most severe and with higher risk of complications.

CONCLUSIONS

Our work confirms previous observations, highlights the importance of early diagnosis and therapy and identifies new risk features such as high IgA and IgG levels for long-term complications.

Serum protein profile analysis in lysosomal storage disorders patients

INTRODUCTION

Serum protein electrophoresis (SPE) is a well-established technique to identify alterations in plasma protein profiles, caused by diseases as multiple myeloma (MM). In addition, it could be a cost-effective technique to discover new plasma biomarkers. Relation between MM and lysosomal storage diseases (LSDs) as Gaucher disease has been set out but, it has not been evaluated on other LSDs nor the utility of the SPE as first step on LSDs biomarkers discovery projects.

MATERIALS AND METHODS

Stored plasma samples at diagnosis from several LSDs patients underwent analysis. Quality control was checked prior to the SPE was analyzed by capillary electrophoresis. The analysis for monoclonal spikes and the differences between each fraction on patients' samples vs the control data previously published, were evaluated. Furthermore, immunoprotein quantification and free light chains ratio were done by nephelometry and turbidimetry.

RESULTS

Seventy-five samples of LSD patients at diagnosis, were assessed. The frequency of the MGUS on LSDs patients was not higher than in general population whereas one lysosomal acid lipase deficiency infant showed increased IgA and kappa deviation. Regarding to the usefulness of SPE in biomarkers discovery, statistically significant differences were observed on SPE fractions between LSDs and healthy population.

DISCUSSION

The evaluation of SPE fractions can be a useful tool to understand pathophysiologic aspects in LDSs and, to simplify new marker discovery projects. In some of them, the MGUS appearance is a risk factor for the MM development despite its frequency is not increased on the studied LSDs at diagnosis.

Glucosylsphingosine but not Saposin C, is the target antigen in Gaucher disease-associated gammopathy

In Gaucher disease type 1 (GD1), genetic deficiency of lysosomal glucocerebrosidase results in the accumulation of glucosylceramide and glucosylsphingosine (GlcSph), that underlie chronic lipid-mediated metabolic inflammation. An important age-related phenotype is high risk of monoclonal gammopathy (MG), including multiple myeloma. We identified GlcSph, a pathological lyso-sphingolipid exclusively elevated in GD, as a mediator of B cell activation and as an antigenic target for GD1-associated MG. Saposin C (SapC), is a lipid-binding protein and activator of lysosomal glucocerebrosidase, which when mutated, cause a rare variant of GD. Sera of GD1 patients with MG of diverse immunoglobulin types were compared to GD patients without gammopathy for reactivity against GlcSph and SapC. We show reactivity of clonal immunoglobulin in GD1 to GlcSph but not to SapC. In two patients with GD1 and gammopathy, GlcSph-reduction therapy with eliglustat resulted in reduction in clonal Ig. Together, our data show that GlcSph but not SapC is the antigenic target in GD1-associated MG and that therapy aimed at reducing the levels of immunogenic lipid resulted in reduction of clonal immunoglobulin in vivo.

Liver involvement in Gaucher disease: A practical review for the hepatologist and the gastroenterologist

Gaucher disease (GD), a rare lysosomal storage disorder caused by deficient glucocerebrosidase activity and consequent accumulation of glycosphingolipids in the mononuclear phagocyte system, may progress to disabling and potentially life-threatening complications when left undiagnosed and untreated. Unfortunately, because of non-specific signs and symptoms and lack of awareness, patients with type 1 GD, the most common non-neuropathic variant, frequently experience diagnostic delays. Since splenomegaly and thrombocytopenia are the dominant clinical features in many GD patients leading to first medical contact, the hepatologist and the gastroenterologist need to be aware of this condition. Liver involvement has been reported in the majority of GD patients, and comprises hepatomegaly, with or without liver enzymes alteration, fibrosis/cirrhosis, portal hypertension, focal liver lesions, and cholelithiasis. Moreover, GD is associated with several biochemical alterations of potential interest for the hepatologist and the gastroenterologist, including hypergammaglobulinemia, hyperferritinemia and metabolic abnormalities, that may lead to misdiagnoses with chronic liver diseases of common etiology, such as primary hemochromatosis, autoimmune liver diseases or nonalcoholic fatty liver disease. This comprehensive review, based on the collaborative experience of physicians managing patients with GD, provides practical information on the clinical, histological and radiological hepatic manifestations of GD aiming at facilitating the diagnosis of GD for the hepatologist and the gastroenterologist.

Are Glucosylceramide-Related Sphingolipids Involved in the Increased Risk for Cancer in Gaucher Disease Patients? Review and Hypotheses

The roles of ceramide and its catabolites, i.e., sphingosine and sphingosine 1-phosphate, in the development of malignancies and the response to anticancer regimens have been extensively described. Moreover, an abundant literature points to the effects of glucosylceramide synthase, the mammalian enzyme that converts ceramide to β-glucosylceramide, in protecting tumor cells from chemotherapy. Much less is known about the contribution of β-glucosylceramide and its breakdown products in cancer progression. In this chapter, we first review published and personal clinical observations that report on the increased risk of developing cancers in patients affected with Gaucher disease, an inborn disorder characterized by defective lysosomal degradation of β-glucosylceramide. The previously described mechanistic links between lysosomal β-glucosylceramidase, β-glucosylceramide and/or β-glucosylphingosine, and various hallmarks of cancer are reviewed. We further show that melanoma tumor growth is facilitated in a Gaucher disease mouse model. Finally, the potential roles of the β-glucosylceramidase protein and its lipidic substrates and/or downstream products are discussed.

Immunoglobulin Abnormalities in Gaucher Disease: an Analysis of 278 Patients Included in the French Gaucher Disease Registry

Gaucher disease (GD) is a rare lysosomal autosomal-recessive disorder due to deficiency of glucocerebrosidase; polyclonal gammopathy (PG) and/or monoclonal gammopathy (MG) can occur in this disease. We aimed to describe these immunoglobulin abnormalities in a large cohort of GD patients and to study the risk factors, clinical significance, and evolution. Data for patients enrolled in the French GD Registry were studied retrospectively. The risk factors of PG and/or MG developing and their association with clinical bone events and severe thrombocytopenia, two markers of GD severity, were assessed with multivariable Cox models and the effect of GD treatment on gammaglobulin levels with linear/logarithmic mixed models. Regression of MG and the occurrence of hematological malignancies were described. The 278 patients included (132 males, 47.5%) were followed up during a mean (SD) of 19 (14) years after GD diagnosis. PG occurred in 112/235 (47.7%) patients at GD diagnosis or during follow-up and MG in 59/187 (31.6%). Multivariable analysis retained age at GD diagnosis as the only independent risk factor for MG (> 30 vs. ≤30 years, HR 4.71, 95%CI [2.40–9.27]; p < 0.001). Risk of bone events or severe thrombocytopenia was not significantly associated with PG or MG. During follow-up, non-Hodgkin lymphoma developed in five patients and multiple myeloma in one. MG was observed in almost one third of patients with GD. Immunoglobulin abnormalities were not associated with the disease severity. However, prolonged surveillance of patients with GD is needed because hematologic malignancies may occur.

Hyperimmunoglobulinemia and IgG Subclass Abnormalities in Children With Gaucher Disease

Gaucher disease (GD) is the most common lysosomal storage disorder, the aim of the current study was to investigate hyperimmunoglobulinemia and abnormalities of serum immunoglobulin G (IgG) subclasses in children with GD and the relation of those findings to the GD phenotype and genotype, duration of enzyme replacement therapy (ERT), and infection frequency. The study included 20 Egyptian children with GD receiving ERT and 20 age-matched and sex-matched healthy children as controls. Serum Ig and serum IgG subclass levels were measured in the children with GD. Serum IgG subclass levels were measured in the control subjects. Hyperimmunoglobulinemia was present in 15 of the 20 (75%) children with GD. In addition, it is found significantly lower IgG2 levels and significantly higher IgG3 levels in the GD group than in the control group (P<0.001 and <0.006, respectively). Patients with 12 infections per year had significantly higher IgG3 levels compared with patients with 6 infections per year (P=0.022). In conclusion, hyperimmunoglobulinemia and IgG subclass abnormalities occur in children with GD who are on ERT and may be related to recurrent infections.

A case of bony lytic lesions in a patient with Gaucher disease

Gaucher disease is a clinically heterogeneous disorder of glucocerebroside metabolism and may present incidentally late in life with unexplained thrombocytopenia, splenomegaly, or bony lesions. Clinicians should be aware that patients with Gaucher disease appear to have an increased risk for developing hematolymphoid malignancies, particularly monoclonal gammopathies and plasma cell myeloma.

[Gaucher Disease type 1 mimicking immune thrombocytopenia: Role of hyperferritinemia and hypergammaglobulinemia in the initial evaluation of an isolated thrombopenia]

INTRODUCTION

Gaucher disease type 1 is a rare genetic disease. It can cause thrombocytopenia. Current guidelines do not support bone marrow examination in front of isolated thrombocytopenia if no evidence suggests malignant hemopathy. This strategy aiming at sparing unnecessary investigations makes such rare diseases more difficult to diagnose.

CASE REPORT

A 31-year-old woman was diagnosed with immune thrombocytopenia according to current guidelines. She presented later with mild splenomegaly. Bone marrow aspirate smears showed Gaucher cells. Gaucher disease was then confirmed. Looking backward, initial biological clues (hyperferritinemia, hypergammaglobulinemia) should have enabled to consider the diagnosis.

CONCLUSION

Gaucher disease type 1 can be responsible for apparently isolated thrombocytopenia. The disease must be looked for if the thrombocytopenia is associated with unexplained hypergammaglobulinemia or hyperferritinemia. Diagnosing immune thrombocytopenia without bone marrow sample requires to systematically pay attention to any clinical or biological abnormality, not to ignore rare differential diagnoses.

Gene expression profile in patients with Gaucher disease indicates activation of inflammatory processes

Gaucher disease (GD) is a rare inherited metabolic disease caused by pathogenic variants in the GBA1 gene. So far, the pathomechanism of GD was investigated mainly in animal models. In order to delineate the molecular changes in GD cells we analysed gene expression profile in cultured skin fibroblasts from GD patients, control individuals and, additionally, patients with Niemann-Pick type C disease (NPC). We used expression microarrays with subsequent validation by qRT-PCR method. In the comparison GD patients vs. controls, the most pronounced relative fold change (rFC) in expression was observed for genes IL13RA2 and IFI6 (up-regulated) and ATOH8 and CRISPLD2 (down-regulated). Products of up-regulated and down-regulated genes were both enriched in genes associated with immune response. In addition, products of down-regulated genes were associated with cell-to-cell and cell-to-matrix interactions, matrix remodelling, PI3K-Akt signalling pathway and a neuronal survival pathway. Up-regulation of PLAU, IFIT1, TMEM158 and down-regulation of ATOH8 and ISLR distinguished GD patients from both NPC patients and healthy controls. Our results emphasize the inflammatory character of changes occurring in human GD cells indicating that further studies on novel therapeutics for GD should consider anti-inflammatory agents.

A 30-Year-Old Carrier of Gaucher Disease with Multiple Myeloma

We are reporting a case of a 30-year-old male with no past medical history who presented with new onset of renal failure, anemia, and splenomegaly and was diagnosed with multiple myeloma. Given the splenomegaly and the patient's Jewish heritage, blood tests were done and the patient was found to be a Gaucher disease carrier. The association of Gaucher disease and multiple myeloma has previously been reported; however, we want to describe the case of a young Gaucher disease carrier who developed multiple myeloma and provide a review of the literature.

Ophthalmic manifestations of Gaucher disease: the most common lysosomal storage disorder

Gaucher disease (GD) results from a deficiency of glucocerebrosidase activity and the subsequent accumulation of the enzyme's metabolites, principally glucosylsphingosine and glucosylceramide. There are three principal forms: Type I, which is the most common, is usually considered non-neuronopathic. Type II, III and IIIc manifest earlier and have neurological sequelae due to markedly reduced enzyme activity. Gaucher's can be associated with ophthalmological sequelae but these have not been systematically reviewed. We therefore performed a comprehensive literature review of all such ophthalmic abnormalities associated with the different types of Gaucher disease. We systematically searched the literature (1950 - present) for functional and structural ocular abnormalities arising in patients with Gaucher disease and found that all subtypes can be associated with ophthalmic abnormalities; these range from recently described intraocular lesions to disease involving the adnexae, peripheral nerves and brain. In summary, Gaucher can affect most parts of the eye. Rarely is it sight-threatening; some but not all manifestations are amenable to treatment, including with enzyme replacement and substrate reduction therapy. Retinal involvement is rare but patients with ocular manifestations should be monitored and treated early to reduce the risk of progression and further complications. As Gaucher disease is also associated with Parkinsons disease and may also confer an increased risk of malignancy (particularly haematological forms and melanoma), any ocular abnormalities should be fully investigated to exclude these potential underlying conditions.

A Review of Gaucher Disease Pathophysiology, Clinical Presentation and Treatments

Gaucher disease (GD, ORPHA355) is a rare, autosomal recessive genetic disorder. It is caused by a deficiency of the lysosomal enzyme, glucocerebrosidase, which leads to an accumulation of its substrate, glucosylceramide, in macrophages. In the general population, its incidence is approximately 1/40,000 to 1/60,000 births, rising to 1/800 in Ashkenazi Jews. The main cause of the cytopenia, splenomegaly, hepatomegaly, and bone lesions associated with the disease is considered to be the infiltration of the bone marrow, spleen, and liver by Gaucher cells. Type-1 Gaucher disease, which affects the majority of patients (90% in Europe and USA, but less in other regions), is characterized by effects on the viscera, whereas types 2 and 3 are also associated with neurological impairment, either severe in type 2 or variable in type 3. A diagnosis of GD can be confirmed by demonstrating the deficiency of acid glucocerebrosidase activity in leukocytes. Mutations in the GBA1 gene should be identified as they may be of prognostic value in some cases. Patients with type-1 GD-but also carriers of GBA1 mutation-have been found to be predisposed to developing Parkinson's disease, and the risk of neoplasia associated with the disease is still subject to discussion. Disease-specific treatment consists of intravenous enzyme replacement therapy (ERT) using one of the currently available molecules (imiglucerase, velaglucerase, or taliglucerase). Orally administered inhibitors of glucosylceramide biosynthesis can also be used (miglustat or eliglustat).

The Coexistence of Multiple Myeloma-associated Amyloid Light-chain Amyloidosis and Fabry Disease in a Hemodialysis Patient

Fabry disease (FD) is an inherited lysosomal disorder caused by an X-linked α-galactosidase A deficiency. We report the case of a 50-year-old male FD patient on hemodialysis who presented with macroglossia-related speaking difficulty and gastrointestinal symptoms. An endoscopic analysis revealed multiple gastric ulcers, and a histological examination led to a diagnosis of amyloid light-chain amyloidosis. Serum free light-chain and bone marrow analyses detected multiple myeloma (MM). Treatment with bortezomib and dexamethasone significantly improved the patient's symptoms. This is the first case to demonstrate a potential pathogenic relationship between FD and MM. The similar gastrointestinal manifestations might have contributed to the diagnostic difficulty.

From rare to common and back again: 60years of lysosomal dysfunction

Sixty years after its discovery, the lysosome is no longer considered as cell's waste bin but as an organelle playing a central role in cell metabolism. Besides its well known association with lysosomal storage disorders (mostly rare and life-threatening diseases), recent data have shown that the lysosome is also a player in some of the most common conditions of our time; and, perhaps even most important, it is not only a target for orphan drugs (rare disease therapeutic approaches) but also a putative target to treat patients suffering from common complex diseases worldwide. Here we review the striking associations linking rare lysosomal storage disorders such as the well-known Gaucher disease, or even the recently discovered, extremely rare Neuronal Ceroid Lipofuscinosis-11 and some of the most frequent, multifaceted and complex disorders of modern society such as cancer, Parkinson's disease and frontotemporal lobar degeneration.

Gaucher iPSC-derived macrophages produce elevated levels of inflammatory mediators and serve as a new platform for therapeutic development

Gaucher disease (GD) is an autosomal recessive disorder caused by mutations in the acid β-glucocerebrosidase (GCase; GBA) gene. The hallmark of GD is the presence of lipid-laden Gaucher macrophages, which infiltrate bone marrow and other organs. These pathological macrophages are believed to be the sources of elevated levels of inflammatory mediators present in the serum of GD patients. The alteration in the immune environment caused by GD is believed to play a role in the increased risk of developing multiple myeloma and other malignancies in GD patients. To determine directly whether Gaucher macrophages are abnormally activated and whether their functional defects can be reversed by pharmacological intervention, we generated GD macrophages by directed differentiation of human induced pluripotent stem cells (hiPSC) derived from patients with types 1, 2, and 3 GD. GD hiPSC-derived macrophages expressed higher levels of tumor necrosis factor α, IL-6, and IL-1β than control cells, and this phenotype was exacerbated by treatment with lipopolysaccharide. In addition, GD hiPSC macrophages exhibited a striking delay in clearance of phagocytosed red blood cells, recapitulating the presence of red blood cell remnants in Gaucher macrophages from bone marrow aspirates. Incubation of GD hiPSC macrophages with recombinant GCase, or with the chaperones isofagomine and ambroxol, corrected the abnormal phenotypes of GD macrophages to an extent that reflected their known clinical efficacies. We conclude that Gaucher macrophages are the likely source of the elevated levels of inflammatory mediators in the serum of GD patients and that GD hiPSC are valuable new tools for studying disease mechanisms and drug discovery.

Clinical manifestations and management of Gaucher disease

Gaucher disease is a rare multi-systemic metabolic disorder caused by the inherited deficiency of the lysosomal enzyme β-glucocerebrosidase, which leads to the accumulation of its normal substrate, glucocerebroside, in tissue macrophages with damage to haematological, visceral and bone systems. Anaemia, thrombocytopenia, enlargement of liver and/or spleen, skeletal abnormalities (osteopenia, lytic lesions, pathological fractures, chronic bone pain, bone crisis, bone infarcts, osteonecrosis and skeletal deformities) are typical manifestations of the most prevalent form of the disease, the so-called non-neuronopathic type 1. However, severity and coexistence of different symptoms are highly variable. The determination of deficient β-glucocerebrosidase activity in leukocytes or fibroblasts by enzymatic assay is the gold standard for the diagnosis of Gaucher disease. Comprehensive and reproducible evaluation and monitoring of all clinically relevant aspects are fundamental for the effective management of Gaucher disease patients. Enzyme replacement therapy has been shown to be effective in reducing glucocerebroside storage burden and diminishing the deleterious effects caused by its accumulation. Tailored treatment plan for each patient should be directed to symptom relief, general improvement of quality of life, and prevention of irreversible damage.

Gaucher disease and comorbidities: B-cell malignancy and parkinsonism

Data emerging from the International Collaborative Gaucher Group (ICGG) Gaucher Registry together with other contemporary clinical surveys have revealed a close association between Gaucher disease and non-Hodgkin's B-cell lymphoma and myeloma and Gaucher disease and Parkinson's disease. Several possible explanations for increased B-cell proliferation and neoplasia in Gaucher disease have been proposed, including the possible influence of sphingosine (derived from the extra lysosomal metabolism of glucosylceramide), gene modifiers, splenectomy and immune system deregulation induced by cytokines, chemokines, and hydrolases released from Gaucher cells. Parkinson's disease is frequently seen in the otherwise-healthy relatives of Gaucher disease patients leading to the finding that GBA mutations represent a genetic risk factor for Parkinson's disease. The mechanism of the association between GBA mutations and Parkinson's disease has yet to be elucidated but the pathogenesis appears distinct from that of Gaucher disease. Several pathogenic pathways have been proposed including lysosomal and/or mitochondrial dysfunction. The effect of Gaucher disease specific therapies on the incidence of cancer or Parkinson's disease are not clear and will likely be evaluated in future ICGG Gaucher Registry studies.

NKT-dependent B-cell activation in Gaucher disease

In this issue of Blood, Nair et al describe a new population of type II natural killer T (NKT) cells with follicular helper phenotype (TFH), which is more abundant in patients and mice with Gaucher disease (GD) and is capable of regulating B-cell activity.

Inhibition of UDP-glucosylceramide synthase in mice prevents Gaucher disease-associated B-cell malignancy

Clonal B-cell proliferation is a frequent manifestation of Gaucher disease - a sphingolipidosis associated with a high risk of multiple myeloma and non-Hodgkin lymphoma. Gaucher disease is caused by genetic deficiency of acid β-glucosidase, the natural substrates of which (β-d-glucosylceramide and β-d-glucosylsphingosine) accumulate, principally in macrophages. Mice with inducible deficiency of β-glucosidase [Gba(tm1Karl/tm1Karl)Tg(MX1-cre)1Cgn/0] serve as an authentic model of human Gaucher disease; we have recently reported clonal B-cell proliferation accompanied by monoclonal serum paraproteins and cognate tumours in these animals. To explore the relationship between B-cell malignancy and the biochemical defect, we treated Gaucher mice with eliglustat tartrate (GENZ 112638), a potent and selective inhibitor of the first committed step in glycosphingolipid biosynthesis. Twenty-two Gaucher mice received 300 mg/kg of GENZ 112638 daily for 3-10 months from 6 weeks of age. Plasma concentrations of β-d-glucosylceramide and the unacylated glycosphingolipid, β-d-glucosylsphingosine, declined. After administration of GENZ 112638 to Gaucher mice for 3-10 months, serum paraproteins were not detected and there was a striking reduction in the malignant lymphoproliferation: neither lymphomas nor plasmacytomas were found in animals that had received the investigational agent. In contrast, 14 out of 60 Gaucher mice without GENZ 112638 treatment developed these tumours; monoclonal paraproteins were detected in plasma from 18 of the 44 age-matched mice with Gaucher disease that had not received GENZ 112638. Long-term inhibition of glycosphingolipid biosynthesis suppresses the development of spontaneous B-cell lymphoma and myeloma in Gaucher mice.

Type II NKT-TFH cells against Gaucher lipids regulate B-cell immunity and inflammation

Chronic inflammation including B-cell activation is commonly observed in both inherited (Gaucher disease [GD]) and acquired disorders of lipid metabolism. However, the cellular mechanisms underlying B-cell activation in these settings remain to be elucidated. Here, we report that β-glucosylceramide 22:0 (βGL1-22) and glucosylsphingosine (LGL1), 2 major sphingolipids accumulated in GD, can be recognized by a distinct subset of CD1d-restricted human and murine type II natural killer T (NKT) cells. Human βGL1-22- and LGL1-reactive CD1d tetramer-positive T cells have a distinct T-cell receptor usage and genomic and cytokine profiles compared with the classical type I NKT cells. In contrast to type I NKT cells, βGL1-22- and LGL1-specific NKT cells constitutively express T-follicular helper (TFH) phenotype. Injection of these lipids leads to an increase in respective lipid-specific type II NKT cells in vivo and downstream induction of germinal center B cells, hypergammaglobulinemia, and production of antilipid antibodies. Human βGL1-22- and LGL1-specific NKT cells can provide efficient cognate help to B cells in vitro. Frequency of LGL1-specific T cells in GD mouse models and patients correlates with disease activity and therapeutic response. Our studies identify a novel type II NKT-mediated pathway for glucosphingolipid-mediated dysregulation of humoral immunity and increased risk of B-cell malignancy observed in metabolic lipid disorders.

Value of plasma chitotriosidase to assess non-neuronopathic Gaucher disease severity and progression in the era of enzyme replacement therapy

Gaucher disease (GD) is caused by deficiency of the enzyme glucocerebrosidase catalysing the regular lysosomal degradation of glucosylceramide. In the common non-neuropathic variant of GD, glucosylceramide-laden macrophages (Gaucher cells) accumulate in various tissues. Gaucher cells secrete chitotriosidase, an active chitinase, resulting in increased plasma chitotriosidase levels, which can be sensitively monitored by an enzyme activity assay. Plasma chitotriosidase is a rough estimate of body burden of Gaucher cells. Non-neuronopathic GD is presently treated by enzyme replacement therapy (ERT) and substrate reduction therapy (SRT). We addressed the question whether plasma chitotriosidase acts as (predictive) marker of clinical manifestations in non-neuronopathic GD patients receiving treatment. Reductions in plasma chitotriosidase during therapy correlated with corrections in liver and spleen volumes and showed positive trends with improvements in haemoglobin and platelet count and bone marrow composition. The occurrence of long-term complications and associated conditions such as multiple myeloma, bone complications, Parkinson's disease, hepatocellular carcinoma and pulmonary hypertension positively correlated with the plasma chitotriosidase level pre-therapy, the average plasma chitotriosidase during 3 years of ERT and the residual plasma chitotriosidase after 2 years of ERT. In summary, plasma chitotriosidase is a valuable marker in the assessment and follow-up of GD patients.

Severe impairment of regulatory T-cells and Th1-lymphocyte polarization in patients with Gaucher disease

We investigated peripheral blood T-lymphocyte subpopulations and intracellular expression of IFN-γ, IL-4, IL-10, and IL-13, by whole blood flow cytometry, in 22 type I Gaucher disease (GD) patients. Results were compared with those of 19 sex- and age-matched controls. Patients with GD exhibited decreased frequencies and absolute numbers of CD3+/CD4+ helper T lymphocytes (40.8 ± 9.8% vs. 49.4 ± 5.7%, p = 0.002, and 0.77 ± 0.33 vs. 1.04 ± 0.28 × 10(9)/μL, p = 0.011), as well as increased frequencies of CD3+CD8+ suppressor T lymphocytes (23.8 ± 8.0% vs. 18.4 ± 3.8%, p = 0.010), resulting in a significantly decreased CD4/CD8 cell ratio (p < 0.001). Moreover, they had significantly increased percentages of IFNγ-producing both CD4+ and CD8+ T cells (p = 0.0003 and p = 0.023, respectively), implying a TH-1 polarization pattern. Finally, patients with GD had decreased percentages and absolute numbers of CD4+CD25(dim) T lymphocytes (p = 0.033 and p = 0.007, respectively), of CD4+CD25(high) T lymphocytes (p = 0.039 and p = 0.016, respectively), and of CD4+CD25(high)FOXP3+ regulatory T cells (p = 0.036 and p = 0.019, respectively). Our results demonstrate that patients with GD have a significant numerical impairment of T-helper lymphocytes and a constitutive TH1 direction pattern of activation of both CD4+ and CD8+ cells, associated with a significant decrease of T-regs. Ineffective T-cell control may explain the chronic inflammatory reaction and the increased incidence of lymphoid malignancies, which have been repeatedly reported among patients with GD.

Gaucher disease: haematological presentations and complications

Gaucher disease (GD) is an autosomal recessive lysosomal storage disease, caused by deficiency of the enzyme glucocerebrosidase, required for the degradation of glycosphingolipids. Clinical manifestations include hepatosplenomegaly, thrombocytopenia, bone disease and a bleeding diathesis, frequently resulting in presentation to haematologists. Historically managed by splenectomy, transfusions and orthopaedic surgery, the development of specific therapy in the form of intravenous enzyme replacement therapy in the 1990s has resulted in dramatic improvements in haematological and visceral disease. Recognition of complications, including multiple myeloma and Parkinson disease, has challenged the traditional macrophage-centric view of the pathophysiology of this disorder. The pathways by which enzyme deficiency results in the clinical manifestations of this disorder are poorly understood; altered inflammatory cytokine profiles, bioactive sphingolipid derivatives and alterations in the bone marrow microenvironment have been implicated. Further elucidating these pathways will serve to advance our understanding not only of GD, but of associated disorders.

Gaucher disease: chemotactic factors and immunological cell invasion in a mouse model

Gaucher disease results from mutations in GBA1 that cause functional disruption of the encoded lysosomal enzyme, acid β-glucosidase. The consequent excess accumulation of glucosylceramide and glucosylsphingosine in lysosomes is central to the disease pathogenesis with classical involvement of macrophage (Mфs) lineage cells of visceral organs, bone, or brain. Several studies have implicated the increased secretion of chemokines and infiltration of a variety of immunological cells into tissues of Gaucher disease patients. Trafficking of immunological cells to the sites of inflammation requires the presence of chemokines. Although increases of different immunological cells and several chemokines are present in Gaucher disease, the specific chemoattractants that cause the increased influx of immunological cells are not fully defined. Here, increased levels of I-309, MCP-5, CXCL-2, CXCL-9, CXCL-10, CXCL-11, CXCL-13, and their corresponding leukocytes, i.e., MOs (monocytes), Mфs, dendritic cells (DCs), polymorphonuclear neutrophils (PMNs), and T, and B cells were identified in the circulation of mice with Gba1 mutations (D409V/null). Sera from D409V/null mice contained chemoattractants for a variety of immunological cells as shown by ex vivo chemotaxis studies and by flow cytometry. Enhanced chemotaxis towards 9V/null sera was found for 9V/null lung-, spleen-, liver-, and bone marrow-derived Mфs (CD11b(+) F480(+)), PMNs (Gr1(high) CD11b(+)), DCs (CD11c(+) CD11b(+)), T lymphocytes (CD3(+) TCRB(+)), and B lymphocytes (B220(+) CD19(+)). These data support these chemotactic factors as causative to increased tissue infiltration of leukocytes in Gaucher disease.

Gaucher disease: a diagnostic challenge for internists

Gaucher disease (GD), the most common inherited lysosomal storage disorder, is a multiorgan disease due to an autosomal recessive defect of the gene encoding glucocerebrosidase enzyme, responsible for the accumulation of glucosylceramide (glucocerebroside) into reticuloendothelial cells, particularly in the liver, spleen and bone marrow. GD is a clinically heterogeneous disorder and it is conventionally classified in type 1 (non-neuronopathic disease), types 2 and 3 (acute and chronic neuronopathic disease, respectively). Features of clinical presentation and organ involvement as well as age, at presentation are highly variable among affected patients. Splenomegaly and/or thrombocytopenia are the most common presenting features either as incidental findings during routine blood count or physical examination. Other possible clinical manifestations can be hepatomegaly with abnormal liver function tests, bone pain often associated with skeletal complications (pathological fractures, avascular necrosis, osteopenia), pulmonary hypertension and, in neuronopathic forms, neurological manifestations (dysfunction of eye motility, mild mental retardation, behavioural difficulties, choreoathetosis and cramp attacks). For all these reasons GD diagnosis is often a real challenge for internists. In the presence of clinical suspicion of GD, the diagnosis has to be confirmed measuring the betaglucocerebrosidase activity in the peripheral leukocytes and by molecular analysis. Each patient needs an accurate initial multisystemic assessment, staging the damage of all the possible organs involved, and the burden of the disease, followed by regular followup. The correct and early diagnosis permits to treat patients properly, avoiding the complications of the disease.

B cell lymphoma and myeloma in murine Gaucher's disease

Multiple myeloma and B cell lymphoma are leading causes of death in Gaucher's disease but the nature of the stimulus driving the often noted clonal expansion of immunoglobulin-secreting B cells and cognate lymphoid malignancy is unknown. We investigated the long-term development of B cell malignancies in an authentic model of non-neuronopathic Gaucher's disease in mice: selective deficiency of β-glucocerebrosidase in haematopoietic cells [Gba(tm1Karl/tm1Karl)Tg(Mx1-cre)1Cgn/0, with excision of exons 9-11 of the murine GBA1 gene, is induced by poly[I:C]. Mice with Gaucher's disease showed visceral storage of β-glucosylceramide and greatly elevated plasma β-glucosylsphingosine [median 57.9 (range 19.8-159) nm; n = 39] compared with control mice from the same strain [median 0.56 (range 0.04-1.38) nm; n = 29] (p < 0.0001). Sporadic fatal B cell lymphomas developed in 11 of 21 GD mice (6-24 months) but only two of eight control animals developed tumours by age 24 months. Unexpectedly, most mice with overt lymphoma had absent or few Gaucher cells but local inflammatory macrophages were present. Eleven of 39 of Gaucher mice developed monoclonal gammopathy, but in the control group only one animal of 25 had clonal immunoglobulin abnormalities. Seven of 10 of the B cell lymphomas were found to secrete a monoclonal paraprotein and the lymphomas stained intensely for pan-B cell markers; reactive T lymphocytes were also present in tumour tissue. In the Gaucher mouse strain, it was notable that, as in patients with this disease, CD138(+) plasma cells frequently surrounded splenic macrophages engorged with glycosphingolipid. Our strain of mice, with inducible deficiency of β-glucocerebrosidase in haematopoietic cells and a high frequency of sporadic lethal B cell malignancies, faithfully recapitulates human Gaucher's disease: it serves as a tractable model to investigate the putative role of bioactive sphingolipids in the control of B cell proliferation and the pathogenesis of myelomatosis-the most prevalent human cancer associated with this disorder.

Gaucher disease and malignancy: a model for cancer pathogenesis in an inborn error of metabolism

Clinical observations spanning almost half a century have demonstrated a consistent association of type 1 Gaucher disease (GD1) and cancers. However, the cellular and molecular bases of the association are not understood. Gaucher disease (GD) is a lysosomal storage disorder due to an inherited deficiency of acid β-glucosidase that underlies the accumulation of glucosylceramide in lysosomes of mononuclear phagocytes and immune dysregulation. The overall cancer risk is markedly increased in GD, and the determinants of malignancy in a subset of patients with GD1 are not known. The association of GD and cancer is most striking for hematological malignancies, with the risk for multiple myeloma estimated at almost 37-fold compared to the general population; some studies have also suggested increased cancer risk for non-hematological malignancies. There is no association of overall severity of GD to risk of cancer, although there is an increased prevalence of splenectomy among patients exhibiting the GD/cancer phenotype. Moreover, there appears to be an increased incidence of multiple consecutive cancers in individual patients. Several factors could contribute to cancer development in GD, including polarization of macrophages to the alternatively activated phenotype, chronic inflammation, chronic B-cell stimulation, splenectomy, hyperferritinemia, lysosomal dysfunction, and endoplasmic reticulum stress. Recent studies have highlighted T-cell dysfunction and modifier genes contributing to an increased cancer risk in GD. Macrophage-targeted enzyme replacement therapy (ERT) reverses systemic features of GD1; while cancer risk appears to be reduced in the era of ERT, it is not known whether this is a direct effect of therapy. Delineation of the mechanisms underlying the increased cancer risk in GD will provide additional novel insights into the role of lipids and macrophages in cancer pathogenesis and, moreover, have the potential to reveal novel therapeutic targets.

A prospective study of bone marrow hematopoietic and mesenchymal stem cells in type 1 Gaucher disease patients

Gaucher disease (GD) is an autosomal recessive disorder characterized by lysosomal glucocerebrosidase (GBA) deficiency leading to hematological and skeletal manifestations. Mechanisms underlying these symptoms have not yet been elucidated. In vivo, bone marrow (BM) mesenchymal stem cells (MSCs) have important role in the regulation of bone mass and in the support of hematopoiesis, thus representing potential candidate that could contribute to the disease. GBA deficiency may also directly impair hematopoietic stem/progenitors cells (HSPCs) intrinsic function and induce hematological defect. In order to evaluate the role of BM stem cells in GD pathophysiology, we prospectively analyzed BM-MSCs and HSPCs properties in a series of 10 patients with type 1 GD. GBA activity was decreased in all tested cell subtypes. GD-MSCs had an impaired growth potential, morphological and cell cycle abnormalities, decreased capacities to differentiate into osteoblasts. Moreover, GD-MSCs secreted soluble factors that stimulated osteoclasts resorbing activities. In vitro and in vivo primitive and mature hematopoiesis were similar between patients and controls. However, GD-MSCs had a lower hematopoietic supportive capacity than those from healthy donors. These data suggest that BM microenvironment is altered in GD and that MSCs are key components of the manifestations observed in GD.