Elevated levels of M-CSF, sCD14 and IL8 in type 1 Gaucher disease

Endocrinological and metabolic profile of Gaucher disease patients treated with enzyme replacement therapy

OBJECTIVES

Gaucher disease (GD) is a lysosomal storage disease caused by glucocerebrosidase (GCase) enzyme deficiency. Gaucher cells transformed from the macrophages by progressive sphingolipid accumulation and infiltrate bone marrow, spleen, liver, and other organs. The accumulation of substrate causes inflammation, compromised cellular homeostasis, and disturbed autophagy. It has been hypothesized that this proinflammatory state of GD leads cytokines and chemokines release. As a result of inflammatory process, the cellular dysfunction caused by disruption of cellular signaling, organelle dysfunction, or autoimmune antibodies may affect endocrine profile of GD patients such as hormone levels, lipid profile, and bone mineral density status.

METHODS

A total of 13 patients confirmed to have GD, 12 non-neuronopathic type and one subacute neuronopathic type, were enrolled in our study.

RESULTS

The median treatment duration in the enzyme therapy was 13.33 years (9-26 years). At least one endocrinological abnormality was detected in blood tests of nine patients. Hyperinsulinism was the most common finding although fasting blood glucose levels HgbA1c levels were normal in all patients. Two patients had osteopenia, and osteoporosis was detected in two patients. Low HDL levels were detected in six patients, but HDL levels below 23 mg/dL associated with disease severity have been detected in two patients who have not receiving enzyme replacement therapy. None of patients had thyroidal dysfunction.

CONCLUSIONS

This study had revealed endocrinological abnormalities in GD patients that have not led any severe morbidity in our patients. However, thyroid hormone abnormalities, insulin resistance, or lipid profile abnormalities may cause unpredictable comorbidities. Endocrinological assessment in GD patients in routine follow-up may prevent possible clinical manifestation in long term as well as can define efficacy of ERT on endocrine abnormalities.

Fabry Disease: Cardiac Implications and Molecular Mechanisms

PURPOSE OF REVIEW

This review explores the interplay among metabolic dysfunction, oxidative stress, inflammation, and fibrosis in Fabry disease, focusing on their potential implications for cardiac involvement. We aim to discuss the biochemical processes that operate in parallel to sphingolipid accumulation and contribute to disease pathogenesis, emphasizing the importance of a comprehensive understanding of these processes.

RECENT FINDINGS

Beyond sphingolipid accumulation, emerging studies have revealed that mitochondrial dysfunction, oxidative stress, and chronic inflammation could be significant contributors to Fabry disease and cardiac involvement. These factors promote cardiac remodeling and fibrosis and may predispose Fabry patients to conduction disturbances, ventricular arrhythmias, and heart failure. While current treatments, such as enzyme replacement therapy and pharmacological chaperones, address disease progression and symptoms, their effectiveness is limited. Our review uncovers the potential relationships among metabolic disturbances, oxidative stress, inflammation, and fibrosis in Fabry disease-related cardiac complications. Current findings suggest that beyond sphingolipid accumulation, other mechanisms may significantly contribute to disease pathogenesis. This prompts the exploration of innovative therapeutic strategies and underscores the importance of a holistic approach to understanding and managing Fabry disease.

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.

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.

Hemochromatosis Mimicked Gaucher Disease: Role of Hyperferritinemia in Evaluation of a Clinical Case

Gaucher disease is a disorder of lysosomes caused by a functional defect of the glucocerebrosidase enzyme. The disease is mainly due to mutations in the GBA1 gene, which determines the gradual storage of glucosylceramide substrate in the patient's macrophages. In this paper, we describe the case of a 38-year-old man who clinically presented with hyperferritinemia, thrombocytopenia, leukopenia, anemia and mild splenomegaly; a diagnosis of hemochromatosis was made 10 years earlier. Re-evaluation of the clinical case led to a suspicion of Gaucher disease, which was confirmed by enzymatic analysis, which was found to be below the normal range, and genetic evaluation, which identified compound heterozygosity N370S/RecNciI. We know that patients suffering from Gaucher disease can also have high ferritin levels. Even if the mechanism underlying the changes in iron metabolism is not yet elucidated, the chronic mild inflammatory state present in these patients probably causes the storage of ferritin in macrophages, resulting in hyperferritinemia. Therefore, in the presence of few typical signs and symptoms of the disease should raise an alarm bell in the clinicians, inducing clinical suspicion of Gaucher disease. Misdiagnosis and diagnostic delay in metabolic diseases could cause irreversible organ damage and delay the start of specific therapy for these patients.

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.

Sphingolipid lysosomal storage diseases: from bench to bedside

Johann Ludwig Wilhelm Thudicum described sphingolipids (SLs) in the late nineteenth century, but it was only in the past fifty years that SL research surged in importance and applicability. Currently, sphingolipids and their metabolism are hotly debated topics in various biochemical fields. Similar to other macromolecular reactions, SL metabolism has important implications in health and disease in most cells. A plethora of SL-related genetic ailments has been described. Defects in SL catabolism can cause the accumulation of SLs, leading to many types of lysosomal storage diseases (LSDs) collectively called sphingolipidoses. These diseases mainly impact the neuronal and immune systems, but other systems can be affected as well. This review aims to present a comprehensive, up-to-date picture of the rapidly growing field of sphingolipid LSDs, their etiology, pathology, and potential therapeutic strategies. We first describe LSDs biochemically and briefly discuss their catabolism, followed by general aspects of the major diseases such as Gaucher, Krabbe, Fabry, and Farber among others. We conclude with an overview of the available and potential future therapies for many of the diseases. We strive to present the most important and recent findings from basic research and clinical applications, and to provide a valuable source for understanding these disorders.

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.

Endocrine and metabolic disorders in patients with Gaucher disease type 1: a review

Background

Gaucher disease (GD) is one of the most prevalent lysosomal storage diseases and is associated with hormonal and metabolic abnormalities, including nutritional status disorders, hypermetabolic state with high resting energy expenditures, peripheral insulin resistance, hypoadiponectinaemia, leptin and ghrelin impairments, hypolipidaemia, linear growth deceleration and growth hormone deficiency, delayed puberty, hypocalcaemia and vitamin D deficiency. Specific treatments for GD such as enzyme replacement therapy and substrate reduction therapy display significant effects on the metabolic profile of GD patients.

Main body of the abstract

Hormonal and metabolic disturbances observed in both adult and paediatric patients with Gaucher disease type 1 (GD1) are discussed in this review. The PubMed database was used to identify articles on endocrine and metabolic disorders in GD1. GD1 appears to facilitate the development of disorders of nutrition, glucose metabolism and vitamin D insufficiency. Metabolic and hormonal diseases may have a significant impact on the course of the underlying disease and patient quality of life.

Conclusions

Conditions relating to hormones and metabolism can be wide-ranging in GD1. Obtained findings were intrinsic to GD either as a deleterious process or a compensatory response and some changes detected may represent co-morbidities. Actively seeking and diagnosing endocrine and metabolic disorders are strongly recommended in GD1 patients to optimize healthcare.

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.

Twenty- five years of biochemical diagnosis of Gaucher disease: the Egyptian experience

BACKGROUND

Gaucher disease is a rare multi-systemic metabolic disorder resulting from the deficiency of acid β-glucosidase activity, with consequent accumulation of glucocerebroside. Less than 15% of mean normal acid β-glucosidase activity in leukocytes is the gold standard for the diagnosis of Gaucher disease, and is generally supplemented by a massive elevation in chitotriosidase activity. We report here our experience in the biochemical diagnosis of Gaucher disease by showing the heterogeneity of the activity of enzymes over 25 years from 1993-2017, through the analysis of 5128 clinically suspected Gaucher disease cases referred to the Biochemical Genetics Department, National Research Centre, as the main reference lab in Egypt for the diagnosis of Inherited Metabolic Disorders.

METHODS

Acid β-glucosidase and chitotriosidase activities were measured in all referred cases. Sphinogmylinase activity was estimated for all cases with normal β-glucosidase activity and moderate elevation of chitotriosidase.

RESULTS

Out of the 5128 suspected cases, 882 (17%) showed a deficiency in acid β-glucosidase activity, accompanied by a raised chitotriosidase activity, ranges (213-66700 umol/l/h) and mean (7255 umol/l/h). Deficient chitotriosidase activity was found in 9 patients (1%) with low β-glucosidase. 451 cases were diagnosed with acid sphingomyelinase deficiency patients (8.8%).

CONCLUSION

Other biochemical markers are needed in addition to chitotriosidase for the diagnosis and follow up. Molecular testing was done to a relatively small number but needs to be done to all diagnosed patients as many mutations are known to predict the course of the disease.

Molecular regulations and therapeutic targets of Gaucher disease

Gaucher disease (GD) is the most common lysosomal storage disease caused by deficiency of beta-glucocerebrosidase (GCase) resulting in lysosomal accumulation of its glycolipid substrate glucosylceramide. The activity of GCase depends on many factors such as proper folding and lysosomal localization, which are influenced by mutations in GCase encoding gene, and regulated by various GCase-binding partners including Saposin C, progranulin and heat shock proteins. In addition, proinflammatory molecules also contribute to pathogenicity of GD. In this review, we summarize the molecules that are known to be important for the pathogenesis of GD, particularly those modulating GCase lysosomal appearance and activity. In addition, small molecules that inhibit inflammatory mediators, calcium ion channels and other factors associated with GD are also described. Discovery and characterization of novel molecules that impact GD are not only important for deciphering the pathogenic mechanisms of the disease, but they also provide new targets for drug development to treat the disease.

Abnormal Sphingolipid World in Inflammation Specific for Lysosomal Storage Diseases and Skin Disorders

Research in recent years has shown that sphingolipids are essential signalling molecules for the proper biological and structural functioning of cells. Long-term studies on the metabolism of sphingolipids have provided evidence for their role in the pathogenesis of a number of diseases. As many inflammatory diseases, such as lysosomal storage disorders and some dermatologic diseases, including psoriasis, atopic dermatitis and ichthyoses, are associated with the altered composition and metabolism of sphingolipids, more studies precisely determining the responsibilities of these compounds for disease states are required to develop novel pharmacological treatment opportunities. It is worth emphasizing that knowledge from the study of inflammatory metabolic diseases and especially the possibility of their treatment may lead to insight into related metabolic pathways, including those involved in the formation of the epidermal barrier and providing new approaches towards workable therapies.

The role of epigenetics in lysosomal storage disorders: Uncharted territory

The study of the contribution of epigenetic mechanisms, including DNA methylation, histone modifications, and microRNAs, to human disease has enhanced our understanding of different cellular processes and diseased states, as well as the effect of environmental factors on phenotypic outcomes. Epigenetic studies may be particularly relevant in evaluating the clinical heterogeneity observed in monogenic disorders. The lysosomal storage disorders are Mendelian disorders characterized by a wide spectrum of associated phenotypes, ranging from neonatal presentations to symptoms that develop in late adulthood. Some lack a tight genotype/phenotype correlation. While epigenetics may explain some of the discordant phenotypes encountered in patients with the same lysosomal storage disorder, especially among patients sharing the same genotype, to date, few studies have focused on these mechanisms. We review three common epigenetic mechanisms, DNA methylation, histone modifications, and microRNAs, and highlight their applications to phenotypic variation and therapeutics. Three specific lysosomal storage diseases, Gaucher disease, Fabry disease, and Niemann-Pick type C disease are presented as prototypical disorders with vast clinical heterogeneity that may be impacted by epigenetics. Our goal is to motivate researchers to consider epigenetics as a mechanism to explain the complexities of biological functions and pathologies of these rare disorders.

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).

Rethinking fatigue in Gaucher disease

Background

Gaucher disease (GD) is a rare lysosomal storage disease caused by deficiency in the enzyme beta-glucocerebrosidase. Along with visceral, hematologic, and bone manifestations, patients may experience chronic fatigue resulting in functional disability and reduced quality of life. Management of the disease includes therapeutic intervention, supportive therapies, and regular monitoring of all clinically relevant disease signs and symptoms. However, current practice guidelines do not include measurement of fatigue or therapeutic goals for fatigue.

Objective

To provide insight regarding key considerations for fatigue in GD.

Methods

We conducted a systematic PubMed literature search and an exploratory, hypothesis-generating survey regarding fatigue in GD.

Results

Our literature search resulted in 19 publications. Of these, 6 were identified that assessed fatigue, including 2 that used specific fatigue assessment instruments. In our survey involving 14 patients with Type 1 GD and 19 physicians, patients ascribed greater importance to fatigue than other disease parameters, while physicians placed more emphasis on objective measures of visceral and hematologic disease manifestations.

Conclusions

Collectively, the results of our literature analysis and survey underscore the need for further investigation and in-office evaluation of fatigue in patients with GD, which will require a reliable, validated, and disease-specific instrument. Criteria for clinically significant fatigue in patients with GD should be established along with the development of a fatigue scale specifically designed for this patient population to provide a more objective means to potentially incorporate fatigue assessment into routine monitoring practices.

Evaluation of neopterin as a biomarker for the monitoring of Gaucher disease patients

OBJECTIVES

Biomarker research is an important area of investigation in Gaucher disease, caused by an inherited deficiency of a lysosomal enzyme, glucocerebrosidase. We evaluated the usefulness of neopterin, as a novel biomarker reflecting chronic inflammation and immune system activation in Gaucher disease and analysed its evolution in response to enzyme replacement therapy (ERT).

METHODS

Circulating plasma neopterin levels in 31 patients with non-neuronopathic Gaucher disease were measured before and after the onset of ERT and were compared with those of 18 healthy controls. Plasma chitotriosidase activity was also monitored, as a reference biomarker, against which we evaluated the evolution of neopterin.

RESULTS

Neopterin levels were significantly increased in treatment-naïve patients (mean 11.90 ± 5.82 nM) compared with controls (6.63 ± 5.59 nM, Mann-Whitney U test P = 0.001), but returned to normal levels (6.92 ± 4.66 nM) following ERT. Investigating the diagnostic value of neopterin by receiver operating characteristic analysis, we found a cut-off value of 7.613 nM that corresponds to an area under the curve of 0.780 and indicates a good discrimination capacity, with a sensitivity of 0.774 and a specificity of 0.778.

DISCUSSION

Our results suggest that measurement of circulating neopterin may be considered as a novel test for the confirmation of diagnosis and monitoring of the efficacy of therapeutic intervention in Gaucher disease. Plasma neopterin levels reflect the global accumulation and activation of Gaucher cells and the extent of chronic immune activation in this disorder.

CONCLUSION

Neopterin may be an alternative storage cell biomarker in Gaucher disease, especially in chitotriosidase-deficient patients.

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.

Activation of p38 Mitogen-Activated Protein Kinase in Gaucher's Disease

Gaucher’s disease is caused by defects in acid β-glucosidase 1 (GBA1) and has been also proposed as an inflammatory disease. GBA1 cleaves glucosylceramide to form ceramide, an established bioactive lipid, and defects in GBA1 lead to aberrant accumulation in glucosylceramide and insufficient formation of ceramide. We investigated if the pro-inflammatory kinase p38 is activated in Gaucher’s disease, since ceramide has been proposed to suppress p38 activation. Three Gaucher’s disease mouse models were employed, and p38 was found to be activated in lung and liver tissues of all Gaucher’s disease mice. Most interestingly, neuronopathic Gaucher’s disease type mice, but not non-neuronopathic ones, displayed significant activation of p38 and up-regulation of p38-inducible proinflammatory cytokines in brain tissues. In addition, all type of Gaucher’s disease mice also showed increases in serum IL-6. As cellular signalling is believed to represent an in vivo inflammatory phenotype in Gaucher’s disease, activation of p38 and possibly its-associated formation of proinflammatory cytokines were assessed in fibroblasts established from neuronopathic Gaucher’s disease mice. In mouse Gaucher’s disease cells, p38 activation and IL-6 formation by TNF-α treatment were enhanced as compared to those of wild type. Furthermore, human fibroblasts from Gaucher’s disease patients also displayed increases in p38 activation and IL-6 formation as comparison to healthy counterpart. These results raise the potential that proinflammatory responses such as p38 activation and IL-6 formation are augmented in Gaucher’s disease.

Pathogenesis of Bone Alterations in Gaucher Disease: The Role of Immune System

Gaucher, the most prevalent lysosomal disorder, is an autosomal recessive inherited disorder due to a deficiency of glucocerebrosidase. Glucocerebrosidase deficiency leads to the accumulation of glucosylceramide primarily in cells of mononuclear-macrophage lineage. Clinical alterations are visceral, hematological, and skeletal. Bone disorder in Gaucher disease produces defects on bone metabolism and structure and patients suffer from bone pain and crisis. Skeletal problems include osteopenia, osteoporosis, osteolytic lesions, and osteonecrosis. On the other hand a chronic stimulation of the immune system is a well-accepted hallmark in this disease. In this review we summarize the latest findings in the mechanisms leading to the bone pathology in Gaucher disease in relationship with the proinflammatory state.

Osteopontin: a potential biomarker of Gaucher disease

Gaucher disease (GD) is one of the most prevalent lysosomal storage disorders and the disorder that has the greatest immune system involvement. Pathologic lipid accumulation in macrophages accounts for a small amount of the additional tissue mass in the liver and spleen. The additional increase may be related to an inflammatory response because Gaucher cells secrete inflammatory mediators. Osteopontin (OPN) is a protein identified in cancer cells and in bone cells that is produced by several types of immune cells including T-cells and macrophages. We report here elevated OPN levels in the plasma of type 1 GD patients and its sensitive response to enzyme replacement therapy. The mean OPN value of GD patients receiving ERT was similar to the values of controls and patients with other lysosomal disorders. When comparing untreated and treated GD patients, the p value was <0.001. In GD, OPN appears to be more sensitive to ERT than chitotriosidase and can be used during the follow-up of patients who are chitotriosidase deficient. Additional extended studies are required to relate variations in the OPN levels to clinical findings and response to therapy in GD patients.

The clinical spectrum and pathophysiology of skeletal complications in lysosomal storage disorders

Lysosomal storage disorders affect multiple organs including the skeleton. Disorders with prominent skeletal symptoms are type 1 and 3 Gaucher disease, the mucopolysaccharidoses, the glycoproteinoses and pycnodysostosis. Clinical manifestations range from asymptomatic radiographical evidence of bone pathology to overt bone crises (Gaucher), short stature with typical imaging features known as dysostosis multiplex (MPS), with spine and joint deformities (mucopolysaccharidoses, mucolipidosis), or osteopetrosis with pathological fractures (pynodysostosis). The pathophysiology of skeletal disease is only partially understood and involves direct substrate storage, inflammation and other complex alterations of cartilage and bone metabolism. Current treatments are enzyme replacement therapy, substrate reduction therapy and hematopoietic stem cell transplantation. However, effects of these interventions on skeletal disease manifestations are less well established and outcomes are highly dependent on disease burden at treatment initiation. It is now clear that adjunctive treatments that target skeletal disease are needed and should be part of future research agenda.

Neuronopathic lysosomal storage diseases: clinical and pathologic findings

BACKGROUND

The lysosomal-autophagocytic system diseases (LASDs) affect multiple body systems including the central nervous system (CNS). The progressive CNS pathology has its onset at different ages, leading to neurodegeneration and early death.

METHODS

Literature review provided insight into the current clinical neurological findings, phenotypic spectrum, and pathogenic mechanisms of LASDs with primary neurological involvement.

CONCLUSIONS

CNS signs and symptoms are variable and related to the disease-specific underlying pathogenesis. LAS dysfunction leads to diverse global cellular consequences in the CNS ranging from specific axonal and dendritic abnormalities to neuronal death. Pathogenic mechanisms for disease progression vary from impaired autophagy, massive storage, regional involvement, to end-stage inflammation. Some of these features are also found in adult neurodegenerative disorders, for example, Parkinson's and Alzheimer's diseases. Lack of effective therapies is a significant unmet medical need.

Bone disease in patients with Gaucher disease

Gaucher disease is an inborn error of metabolism due to a deficiency of the lysosomal enzyme glucocerebrosidase. As a result of this deficiency, the substrate glucocerebroside accumulates in the liver, spleen, bone and bone marrow. Bone involvement can lead to abnormalities in bone growth, bone remodeling, bone infarcts, aseptic necrosis, osteonecrosis, increased fracture risk and lytic bone lesions. Patients may experience bone pain and bone crises related to bone infarcts. There is evidence of abnormal bone metabolism in both bone resorption and bone formation based upon biochemical abnormalities found in patients. In addition, both immunological and coagulation abnormalities have in part been implicated in the causation of bone disease. Treatment with enzyme replacement therapy and substrate reduction therapy has led to improvement in both the symptoms and the radiographic abnormalities seen in these patients. It is unknown whether these treatments lower fracture risk.

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.

The role of inflammation in sporadic and familial Parkinson's disease

The etiology of Parkinson's disease (PD) is complex and most likely involves numerous environmental and heritable risk factors. Interestingly, many genetic variants, which have been linked to familial forms of PD or identified as strong risk factors, also play a critical role in modulating inflammatory responses. There has been considerable debate in the field as to whether inflammation is a driving force in neurodegeneration or simply represents a response to neuronal death. One emerging hypothesis is that inflammation plays a critical role in the early phases of neurodegeneration. In this review, we will discuss emerging aspects of both innate and adaptive immunity in the context of the pathogenesis of PD. We will highlight recent data from genetic and functional studies that strongly support the theory that genetic susceptibility plays an important role in modulating immune pathways and inflammatory reactions, which may precede and initiate neuronal dysfunction and subsequent neurodegeneration. A detailed understanding of such cellular and molecular inflammatory pathways is crucial to uncover pathogenic mechanisms linking sporadic and hereditary PD and devise tailored neuroprotective interventions.

Gaucher disease: transcriptome analyses using microarray or mRNA sequencing in a Gba1 mutant mouse model treated with velaglucerase alfa or imiglucerase

Gaucher disease type 1, an inherited lysosomal storage disorder, is caused by mutations in GBA1 leading to defective glucocerebrosidase (GCase) function and consequent excess accumulation of glucosylceramide/glucosylsphingosine in visceral organs. Enzyme replacement therapy (ERT) with the biosimilars, imiglucerase (imig) or velaglucerase alfa (vela) improves/reverses the visceral disease. Comparative transcriptomic effects (microarray and mRNA-Seq) of no ERT and ERT (imig or vela) were done with liver, lung, and spleen from mice having Gba1 mutant alleles, termed D409V/null. Disease-related molecular effects, dynamic ranges, and sensitivities were compared between mRNA-Seq and microarrays and their respective analytic tools, i.e. Mixed Model ANOVA (microarray), and DESeq and edgeR (mRNA-Seq). While similar gene expression patterns were observed with both platforms, mRNA-Seq identified more differentially expressed genes (DEGs) (∼3-fold) than the microarrays. Among the three analytic tools, DESeq identified the maximum number of DEGs for all tissues and treatments. DESeq and edgeR comparisons revealed differences in DEGs identified. In 9V/null liver, spleen and lung, post-therapy transcriptomes approximated WT, were partially reverted, and had little change, respectively, and were concordant with the corresponding histological and biochemical findings. DEG overlaps were only 8–20% between mRNA-Seq and microarray, but the biological pathways were similar. Cell growth and proliferation, cell cycle, heme metabolism, and mitochondrial dysfunction were most altered with the Gaucher disease process. Imig and vela differentially affected specific disease pathways. Differential molecular responses were observed in direct transcriptome comparisons from imig- and vela-treated tissues. These results provide cross-validation for the mRNA-Seq and microarray platforms, and show differences between the molecular effects of two highly structurally similar ERT biopharmaceuticals.

Clinical and biochemical differences in patients having Parkinson disease with vs without GBA mutations

IMPORTANCE

Biochemical abnormalities present in GBA (mut/wt) carriers may offer new pathogenetic insights to and potential therapeutic targets in Parkinson disease (PD).

OBJECTIVE

To determine whether patients having PD with vs without GBA mutations differ in clinical phenotype or plasma protein expression.

DESIGN AND SETTING

Case-control study of patients having PD with vs without GBA mutations. Clinical characteristics were compared between groups, and biochemical profiling of 40 plasma proteins was performed to identify proteins that differed in expression between groups.

PARTICIPANTS

The discovery cohort included 20 patients having PD with GBA mutations. Clinical characteristics of GBA-associated PD cases were compared with those of 242 patients having PD in whom GBA mutations were excluded by full gene sequencing.

MAIN OUTCOME MEASURES

Biochemical profiling was available for all 20 GBA-associated PD cases, as well as a subset (87 of 242) of the GBA-negative PD cases. The replication cohort included 19 patients having PD with GBA mutations and 41 patients having PD without GBA mutations.

RESULTS

Compared with patients having PD without GBA mutations, patients having PD with GBA mutations were younger at disease onset (P = .04) and were more likely to demonstrate cognitive dysfunction (P = .001). In a multiple regression model that included age, sex, and assay batch as covariates, GBA mutation status was significantly associated with plasma levels of interleukin 8 (P = .001), monocyte chemotactic protein 1 (P = .008), and macrophage inflammatory protein 1α (P = .005). The association between interleukin 8 and GBA mutation status was replicated (P = .03) in a separate cohort of patients having PD with vs without GBA mutations.

CONCLUSIONS AND RELEVANCE

Patients having PD with GBA mutations have earlier age at disease onset and are more likely to demonstrate cognitive dysfunction. Monocyte-associated inflammatory mediators may be elevated in patients having PD with GBA mutations.

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.

Enhanced differentiation of osteoclasts from mononuclear precursors in patients with Gaucher disease

Gaucher disease (GD) is an autosomal recessive disorder caused by deficiency of β-glucocerebrosidase. Storage of glucosylceramide in reticuloendothelial cells results in multiorgan pathology including bone disease. Established skeletal disease may remain problematic despite Gaucher-specific treatment. Both osteopenia and osteonecrosis have been described but the underlying pathophysiology, in particular the role of monocyte-derived osteoclasts is not well defined. The objective of this study was to explore the effect of glucocerebrosidase deficiency, inhibition and replacement on osteoclast development and function. In cultures derived from GD patients, or where GBA was chemically inhibited multinucleate giant cells expressing markers of osteoclast differentiation occurred earlier and in greater numbers compared to normal controls and the functional capacity of osteoclasts for bone resorption was enhanced. Increases in osteoclast number and activity correlated with radiological markers of active bone disease. Abnormalities were reversed by addition of specific therapies and were attenuated by co-culture with cells derived from healthy controls (HCs). Numbers of osteoblast lineage cells in the peripheral blood were mismatched to osteoclast precursors indicating uncoupling of osteoblast-osteoclast regulation which may further impact on bone remodelling. Elucidation of the underlying mechanisms of these changes will suggest rational therapies for the most disabling aspect of this condition.

Gaucher disease

Gaucher disease is an autosomal recessive condition due to glucocerebrosidase deficiency responsible for the lysosomal accumulation of glucosylceramide, a complex lipid derived from cell membranes, mainly in macrophages. It is due to mutations mostly in the GBA gene, although saposine C deficiency is due to mutations in the PSAP gene. It encompasses an extremely heterogeneous spectrum of clinical involvement from the fetus to adulthood. Splenomegaly, blood cytopenia, and bone involvement are the main manifestations of Gaucher disease, but nervous system degeneration is observed in about 5-10% of patients. The accumulation in neurons of glucosylceramide and its derivative, psychosine, are thought to underlie neuronal dysfunction and death, although Gaucher cells that mostly accumulate such substances are mainly macrophages. Enzyme replacement therapy dramatically improves the outcome of patients because of its extreme efficacy in the treatment of the systemic involvement. However, it has only limited effects on most neurological signs.

Neuronal forms of Gaucher disease

Gaucher disease is an inherited metabolic disease caused by the defective activity of the lysosomal enzyme, glucosylceramidase (GlcCerase), which is responsible for the last step in the degradation of complex glycosphingolipids. As a result, glucosylceramide (GlcCer) accumulates intracellularly. Little is known about the mechanisms by which GlcCer accumulation leads to Gaucher disease, particularly for the types of the disease in which severe neuropathology occurs. We now summarize recent advances in this area and in particular focus in the biochemical and cellular pathways that may cause neuronal defects. Most recent work has taken advantage of newly available mouse models, which mimic to a large extent human disease progression. Finally, we discuss observations of a genetic link between Gaucher disease and Parkinson's disease and discuss how this link has stimulated research into the basic biology of the previously underappreciated glycosphingolipid, GlcCer.