How Do Physical Activity and Exercise Affect Fabry Disease? Exploring a New Opportunity.

BACKGROUND: Fabry disease (FD) is a multisystem, monogenic, X-linked storage disorder caused by mutations in the GLA gene, resulting in reduced alfa-galactosidase A enzyme activity. This effect leads to the accumulation of glycosphingolipids, particularly globotriaosylceramide, in various tissues, including the heart, kidney, vasculature, smooth muscle, and peripheral nervous system. Hemizygous males are usually more severely affected than females, in whom random inactivation of an X chromosome may lead to variable phenotype. SUMMARY: Among the manifestations of FD, exercise intolerance is commonly diagnosed but often underestimated, even though it significantly limits quality of life, especially in young patients. This review primarily discusses the various pathophysiological mechanisms involved in exercise intolerance in FD patients, such as altered muscle composition, compromised cardiopulmonary framework, and peripheral neuropathy. Secondarily, it explores the potential effect of available therapy, including enzyme replacement therapy and chaperone therapy (migalastat), in reducing exercise intolerance while considering the potential impact of physical activity and exercise training as adjunctive treatments. CONCLUSION: Exercise intolerance has a major impact on the well-being of people with FD. Exercise training can play an important role in addition to drug therapy.

Inflammatory and Cardiovascular Biomarkers to Monitor Fabry Disease Progression.

Fabry disease is an invalidating multisystemic disorder affecting α-Galactosidase, a rate-limiting hydrolase dedicated to lipid catabolism. Non-metabolized substrates, such as Globotriaosylceramide and its derivatives trigger the direct or indirect activation of inflammatory events and endothelial dysfunction. In spite of the efficacy demonstrated by enzyme replacement therapy or pharmacological chaperones in delaying disease progression, few studies have analyzed whether these treatments can improve the pro-inflammatory state of FD patients. Therefore, the aim of this work was to assess cytokines and cardiovascular risk-related proteins detectable in plasma from FD patients, whether treated or not with ERT, to evaluate the reliability of these markers in monitoring disease stage and treatment effects. We identified inflammatory and endothelial dysfunction markers (ADAMTS-13, TNF-α, GDF-15, MIP-1ß, VEGFA, MPO, and MIC-1) that cooperate in a common pathway and are increased in FD patients' plasma samples. As shown by the assessment of these proteins over time, they can help to evaluate the risk of higher severity in FD, as well as ERT effects. Even though the analyzed proteins cannot be considered as proper biomarkers due to their non-specificity to FD, taken together they can provide a signature of reference molecules with prognostic value for early diagnosis, and evaluation of disease progression and treatment efficacy, using blood samples.

Unraveling mucolipidosis type III gamma through whole genome sequencing in late-onset retinitis pigmentosa: a case report.

BACKGROUND: We describe the case of a 47-year-old man referred to a retinal clinic and diagnosed with late-onset retinitis pigmentosa. Surprisingly, genetic testing revealed compound heterozygous pathogenic variants in GNPTG, leading to the diagnosis of the autosomal recessive lysosomal storage disorder mucolipidosis type III gamma. Mucolipidosis type III gamma is typically diagnosed during childhood due to symptoms relating to skeletal dysplasia. Retinal dystrophy is not a common phenotypic feature. CASE PRESENTATION: Ophthalmologic examination was consistent with a mild form of retinitis pigmentosa and included fundus photography, measurement of best-corrected visual acuity, optical coherence tomography, electroretinogram and visual field testing. Extraocular findings included joint restriction and pains from an early age leading to bilateral hip replacement by age 30, aortic insufficiency, and hypertension. Genetic analysis was performed by whole genome sequencing filtered for a gene panel of 325 genes associated with retinal disease. Two compound heterozygous pathogenic variants were identified in GNPTG, c.347_349del and c.607dup. The diagnosis of mucolipidosis type III gamma was confirmed biochemically by measurement of increased activities of specific lysosomal enzymes in plasma. CONCLUSION: To our knowledge this is the first description of retinitis pigmentosa caused by compound heterozygous variants in GNPTG, providing further indications that late-onset retinal dystrophy is part of the phenotypic spectrum of mucolipidosis type III gamma.

Deterioration of visual quality and acuity as the first sign of ceroid lipofuscinosis type 3 (CLN3), a rare neurometabolic disease.

Ceroid lipofuscinosis type 3 (CLN3) is an autosomal recessive, neurodegenerative metabolic disease. Typical clinical symptoms include progressive visual loss, epilepsy of unknown etiology and dementia. Presence of lipofuscin deposits with typical pattern of 'fingerprints' and vacuolized lymphocytes suggest the diagnosis of CLN3. Cause of CLN3 are mutations in the CLN3 gene, among which the most frequently found is the large deletion 1.02 kb spreading on exons 7 and 8. We present 4 patients from 2 families, in whom the deterioration of visual quality and acuity was observed as first clinical sign, when they were a few years old and it was successively accompanied by symptoms of neurologic deterioration (like generalized convulsions with consciousness impairment). In all patients the 1.02 kb deletion in the CLN3 gene was detected in homo- or heterozygosity with other CLN3 pathogenic variant. Ultrastructural studies revealed abnormal structures corresponding to 'fingerprint' profiles (FPPs) in conjunctival endothelial cells. It should be emphasized that in patients with blindness of unknown cause the diagnosis of ceroid lipofuscinosis should be considered and in older children-especially CLN3. The facility of the analysis for the presence of 1.02 kb deletion and economic costs are a solid argument for intensive use of this test in the diagnostic procedure of CLN3.

A human iPSC-derived inducible neuronal model of Niemann-Pick disease, type C1.

BACKGROUND: Niemann-Pick disease, type C (NPC) is a childhood-onset, lethal, neurodegenerative disorder caused by autosomal recessive mutations in the genes NPC1 or NPC2 and characterized by impaired cholesterol homeostasis, a lipid essential for cellular function. Cellular cholesterol levels are tightly regulated, and mutations in either NPC1 or NPC2 lead to deficient transport and accumulation of unesterified cholesterol in the late endosome/lysosome compartment, and progressive neurodegeneration in affected individuals. Previous cell-based studies to understand the NPC cellular pathophysiology and screen for therapeutic agents have mainly used patient fibroblasts. However, these do not allow modeling the neurodegenerative aspect of NPC disease, highlighting the need for an in vitro system that permits understanding the cellular mechanisms underlying neuronal loss and identifying appropriate therapies. This study reports the development of a novel human iPSC-derived, inducible neuronal model of Niemann-Pick disease, type C1 (NPC1). RESULTS: We generated a null i3Neuron (inducible × integrated × isogenic) (NPC1-/- i3Neuron) iPSC-derived neuron model of NPC1. The NPC1-/- and the corresponding isogenic NPC1+/+ i3Neuron cell lines were used to efficiently generate homogenous, synchronized neurons that can be used in high-throughput screens. NPC1-/- i3Neurons recapitulate cardinal cellular NPC1 pathological features including perinuclear endolysosomal storage of unesterified cholesterol, accumulation of GM2 and GM3 gangliosides, mitochondrial dysfunction, and impaired axonal lysosomal transport. Cholesterol storage, mitochondrial dysfunction, and axonal trafficking defects can be ameliorated by treatment with 2-hydroxypropyl-ß-cyclodextrin, a drug that has shown efficacy in NPC1 preclinical models and in a phase 1/2a trial. CONCLUSION: Our data demonstrate the utility of this new cell line in high-throughput drug/chemical screens to identify potential therapeutic agents. The NPC1-/- i3Neuron line will also be a valuable tool for the NPC1 research community to explore the pathological mechanisms contributing to neuronal degeneration.

Body composition and 6 minute walking ability in late-onset pompe disease patients after 9 years of enzyme replacement therapy.

OBJECTIVE: Pompe disease is a rare autosomal recessive disorder caused by the deficiency of acid α-glycosidase resulting in accumulation of glycogen in the lysosomes. The late-onset form of the disease (LOPD) causes primarily progressive muscle weakness and respiratory insufficiency. Enzyme replacement therapy (ERT) introduced in 2006, showed mild improvement or stabilization of the symptoms although long-term data are limited. Aim of the study was to describe the progression of body composition and walking ability in LOPD patients receiving ERT consistently for 9 years. METHODS: Lean body mass, bone mineral density, body fat and 6 min walking distance were assessed in three male and three female LOPD patients (height 165.8 ± 11.2 cm, age 42.3 ± 11.8yrs, body mass 71.1 ± 20.8 kg, at study entry), every three years, for 9 years since ERT initiation (T0, T3, T6, T9). RESULTS: Total body and upper extremities' lean mass remained unchanged (p < 0.05), but it was decreased for the lower extremities (T3:13.06 ± 3.848 kg vs. T9:11.63 ± 3.49 kg, p < 0.05). Lean body mass was not significantly different after 9 years of ERT compared to before the ERT initiation (T0 to T9). Bone mineral density remained unchanged. Percent body fat increased (T0:39.1 ± 10.3%, vs. T9:43.1 ± 10.4%, p < 0.05). Six minute walking distance tended to increase after 3 years of ERT and decreased gradually thereafter, with no difference between T0-T9. Lean mass of the lower extremities adjusted for body weight was significantly correlated with 6 min walking distance (r = 0.712, p < 0.05). CONCLUSION: The current data show that enzyme replacement therapy may preserve lean body mass, bone mineral density and walking capacity in LOPD patients.

Reduction of glutamate neurotoxicity: A novel therapeutic approach for Niemann-Pick disease, type C1.

Niemann-Pick disease, type C1 is a progressive, lethal, neurodegenerative disorder due to endolysosomal storage of unesterified cholesterol. Cerebellar ataxia, as a result of progressive loss of cerebellar Purkinje neurons, is a major symptom of Nieman-Pick disease, type C1. Comparing single cell RNAseq data from control (Npc1+/+) and mutant (Npc1-/-) mice, we observed significantly decreased expression of Slc1a3 in Npc1-/- astrocytes. Slc1a3 encodes a glutamate transporter (GLAST, EAAT1) which functions to decrease glutamate concentrations in the post synaptic space after neuronal firing. Glutamate is an excitatory neurotransmitter and elevated extracellular levels of glutamate can be neurotoxic. Impaired EAAT1 function underlies type-6 episodic ataxia, a rare disorder with progressive cerebellar dysfunction, thus suggesting that impaired glutamate uptake in Niemann-Pick disease, type C1 could contribute to disease progression. We now show that decreased expression of Slc1a3 in Npc1-/- mice has functional consequences that include decreased surface protein expression and decreased glutamate uptake by Npc1-/- astrocytes. To test whether glutamate neurotoxicity plays a role in Niemann-Pick disease, type C1 progression, we treated NPC1 deficient mice with ceftriaxone and riluzole. Ceftriaxone is a ß-lactam antibiotic that is known to upregulate the expression of Slc1a2, an alternative glial glutamate transporter. Although ceftriaxone increased Slc1a2 expression, we did not observe a treatment effect in NPC1 mutant mice. Riluzole is a glutamate receptor antagonist that inhibits postsynaptic glutamate receptor signaling and reduces the release of glutamate. We found that treatment with riluzole increased median survival in Npc1-/- by 12%. Given that riluzole is an approved drug for the treatment of amyotrophic lateral sclerosis, repurposing of this drug may provide a novel therapeutic approach to decrease disease progression in Niemann-Pick disease type, C1 patients.

Carnitine is a pharmacological allosteric chaperone of the human lysosomal α-glucosidase.

Pompe disease is an inherited metabolic disorder due to the deficiency of the lysosomal acid α-glucosidase (GAA). The only approved treatment is enzyme replacement therapy with the recombinant enzyme (rhGAA). Further approaches like pharmacological chaperone therapy, based on the stabilising effect induced by small molecules on the target enzyme, could be a promising strategy. However, most known chaperones could be limited by their potential inhibitory effects on patient's enzymes. Here we report on the discovery of novel chaperones for rhGAA, L- and D-carnitine, and the related compound acetyl-D-carnitine. These drugs stabilise the enzyme at pH and temperature without inhibiting the activity and acted synergistically with active-site directed pharmacological chaperones. Remarkably, they enhanced by 4-fold the acid α-glucosidase activity in fibroblasts from three Pompe patients with added rhGAA. This synergistic effect of L-carnitine and rhGAA has the potential to be translated into improved therapeutic efficacy of ERT in Pompe disease.

Intrathecal enzyme replacement for cognitive decline in mucopolysaccharidosis type I, a randomized, open-label, controlled pilot study.

Central nervous system manifestations of mucopolysaccharidosis type I (MPS I) such as cognitive impairment, hydrocephalus, and spinal cord compression are inadequately treated by intravenously-administered enzyme replacement therapy with laronidase (recombinant human alpha-L-iduronidase). While hematopoietic stem cell transplantation treats neurological symptoms, this therapy is not generally offered to attenuated MPS I patients. This study is a randomized, open-label, controlled pilot study of intrathecal laronidase in eight attenuated MPS I patients with cognitive impairment. Subjects ranged between 12 years and 50 years old with a median age of 18 years. All subjects had received intravenous laronidase prior to the study over a range of 4 to 10 years, with a mean of 7.75 years. Weekly intravenous laronidase was continued throughout the duration of the study. The randomization period was one year, during which control subjects attended all study visits and assessments, but did not receive any intrathecal laronidase. After the first year, all eight subjects received treatment for one additional year. There was no significant difference in neuropsychological assessment scores between control or treatment groups, either over the one-year randomized period or at 18 or 24 months. However, there was no significant decline in scores in the control group either. Adverse events included pain (injection site, back, groin), headache, neck spasm, and transient blurry vision. There were seven serious adverse events, one judged as possibly related (headache requiring hospitalization). There was no significant effect of intrathecal laronidase on cognitive impairment in older, attenuated MPS I patients over a two-year treatment period. A five-year open-label extension study is underway.

The definition of neuronopathic Gaucher disease.

Neuronopathic Gaucher disease (nGD) has a very wide clinical and genotypic spectrum. However, there is no consensus definition of nGD, including no description of how best to diagnostically separate the acute form-Gaucher type 2-from the subacute or chronic form-Gaucher type 3. In this article, we define the various forms of Gaucher disease with particular emphasis on the presence of gaze palsy in all patients with nGD. This consensus definition will help in both clinical diagnosis and appropriate patient recruitment to upcoming clinical trials.

Current concepts in the neuropathogenesis of mucolipidosis type IV.

Mucolipidosis type IV (MLIV) is an autosomal recessive, lysosomal storage disorder causing progressively severe intellectual disability, motor and speech deficits, retinal degeneration often culminating in blindness, and systemic disease causing a shortened lifespan. MLIV results from mutations in the gene MCOLN1 encoding the transient receptor potential channel mucolipin-1. It is an ultra-rare disease and is currently known to affect just over 100 diagnosed individuals. The last decade has provided a wealth of research focused on understanding the role of the enigmatic mucolipin-1 protein in cell and brain function and how its absence causes disease. This review explores our current understanding of the mucolipin-1 protein in relation to neuropathogenesis in MLIV and describes recent findings implicating mucolipin-1's important role in mechanistic target of rapamycin and TFEB (transcription factor EB) signaling feedback loops as well as in the function of the greater endosomal/lysosomal system. In addition to addressing the vital role of mucolipin-1 in the brain, we also report new data on the question of whether haploinsufficiency as would be anticipated in MCOLN1 heterozygotes is associated with any evidence of neuron dysfunction or disease. Greater insights into the role of mucolipin-1 in the nervous system can be expected to shed light not only on MLIV disease but also on numerous processes governing normal brain function. This article is part of the Special Issue "Lysosomal Storage Disorders".

Unique molecular signature in mucolipidosis type IV microglia.

BACKGROUND: Lysosomal storage diseases (LSD) are a large family of inherited disorders characterized by abnormal endolysosomal accumulation of cellular material due to catabolic enzyme and transporter deficiencies. Depending on the affected metabolic pathway, LSD manifest with somatic or central nervous system (CNS) signs and symptoms. Neuroinflammation is a hallmark feature of LSD with CNS involvement such as mucolipidosis type IV, but not of others like Fabry disease. METHODS: We investigated the properties of microglia from LSD with and without major CNS involvement in 2-month-old mucolipidosis type IV (Mcoln1-/-) and Fabry disease (Glay/-) mice, respectively, by using a combination of flow cytometric, RNA sequencing, biochemical, in vitro and immunofluorescence analyses. RESULTS: We characterized microglia activation and transcriptome from mucolipidosis type IV and Fabry disease mice to determine if impaired lysosomal function is sufficient to prime these brain-resident immune cells. Consistent with the neurological pathology observed in mucolipidosis type IV, Mcoln1-/- microglia demonstrated an activation profile with a mixed neuroprotective/neurotoxic expression pattern similar to the one we previously observed in Niemann-Pick disease, type C1, another LSD with significant CNS involvement. In contrast, the Fabry disease microglia transcriptome revealed minimal alterations, consistent with the relative lack of CNS symptoms in this disease. The changes observed in Mcoln1-/- microglia showed significant overlap with alterations previously reported for other common neuroinflammatory disorders including Alzheimer's, Parkinson's, and Huntington's diseases. Indeed, our comparison of microglia transcriptomes from Alzheimer's disease, amyotrophic lateral sclerosis, Niemann-Pick disease, type C1 and mucolipidosis type IV mouse models showed an enrichment in "disease-associated microglia" pattern among these diseases. CONCLUSIONS: The similarities in microglial transcriptomes and features of neuroinflammation and microglial activation in rare monogenic disorders where the primary metabolic disturbance is known may provide novel insights into the immunopathogenesis of other more common neuroinflammatory disorders. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01067742, registered on February 12, 2010.

Comprehensive behavioral and biochemical outcomes of novel murine models of GM1-gangliosidosis and Morquio syndrome type B.

Deficiencies in the lysosomal hydrolase ß-galactosidase (ß-gal) lead to two distinct diseases: the skeletal disease Morquio syndrome type B, and the neurodegenerative disease GM1-gangliosidosis. Utilizing CRISPR-Cas9 genome editing, the mouse ß-gal encoding gene, Glb1, was targeted to generate both models of ß-gal deficiency in a single experiment. For Morquio syndrome type B, the common human missense mutation W273L (position 274 in mice) was introduced into the Glb1 gene (Glb1W274L), while for GM1-gangliosidosis, a 20 bp mutation was generated to remove the catalytic nucleophile of ß-gal (ß-gal-/-). Glb1W274L mice showed a significant reduction in ß-gal enzyme activity (8.4-13.3% of wildtype), but displayed no marked phenotype after one year. In contrast, ß-gal-/- mice were devoid of ß-gal enzyme activity (≤1% of wildtype), resulting in ganglioside accumulation and severe cellular vacuolation throughout the central nervous system (CNS). ß-gal-/- mice also displayed severe neuromotor and neurocognitive dysfunction, and as the disease progressed, the mice became emaciated and succumbed to the disease by 10 months of age. Overall, in addition to generating a novel murine model that phenotypically resembles GM1-gangliosidosis, the first model of ß-galactosidase deficiency with residual enzyme activity has been developed.

Pathobiology of Christianson syndrome: Linking disrupted endosomal-lysosomal function with intellectual disability and sensory impairments.

Christianson syndrome (CS) is a recently described rare neurogenetic disorder presenting early in life with a broad range of neurological symptoms, including severe intellectual disability with nonverbal status, hyperactivity, epilepsy, and progressive ataxia due to cerebellar atrophy. CS is due to loss-of-function mutations in SLC9A6, encoding NHE6, a sodium-hydrogen exchanger involved in the regulation of early endosomal pH. Here we review what is currently known about the neuropathogenesis of CS, based on insights from experimental models, which to date have focused on mechanisms that affect the CNS, specifically the brain. In addition, parental reports of sensory disturbances in their children with CS, including an apparent insensitivity to pain, led us to explore sensory function and related neuropathology in Slc9a6 KO mice. We present new data showing sensory deficits in Slc9a6 KO mice, which had reduced behavioral responses to noxious thermal and mechanical stimuli (Hargreaves and Von Frey assays, respectively) compared to wild type (WT) littermates. Immunohistochemical and ultrastructural analysis of the spinal cord and peripheral nervous system revealed intracellular accumulation of the glycosphingolipid GM2 ganglioside in KO but not WT mice. This cellular storage phenotype was most abundant in neurons of lamina I-II of the dorsal horn, a major relay site in the processing of painful stimuli. Spinal cords of KO mice also exhibited changes in astroglial and microglial populations throughout the gray matter suggestive of a neuroinflammatory process. Our findings establish the Slc9a6 KO mouse as a relevant tool for studying the sensory deficits in CS, and highlight selective vulnerabilities in relevant cell populations that may contribute to this phenotype. How NHE6 loss of function leads to such a multifaceted neurological syndrome is still undefined, and it is likely that NHE6 is involved with many cellular processes critical to normal nervous system development and function. In addition, the sensory issues exhibited by Slc9a6 KO mice, in combination with our neuropathological findings, are consistent with NHE6 loss of function impacting the entire nervous system. Sensory dysfunction in intellectually disabled individuals is challenging to assess and may impair patient safety and quality of life. Further mechanistic studies of the neurological impairments underlying CS and other genetic intellectual disability disorders must also take into account mechanisms affecting broader nervous system function in order to understand the full range of associated disabilities.

Dose-Dependent Prevention of Metabolic and Neurologic Disease in Murine MPS II by ZFN-Mediated In Vivo Genome Editing.

Mucopolysaccharidosis type II (MPS II) is an X-linked recessive lysosomal disorder caused by deficiency of iduronate 2-sulfatase (IDS), leading to accumulation of glycosaminoglycans (GAGs) in tissues of affected individuals, progressive disease, and shortened lifespan. Currently available enzyme replacement therapy (ERT) requires lifelong infusions and does not provide neurologic benefit. We utilized a zinc finger nuclease (ZFN)-targeting system to mediate genome editing for insertion of the human IDS (hIDS) coding sequence into a "safe harbor" site, intron 1 of the albumin locus in hepatocytes of an MPS II mouse model. Three dose levels of recombinant AAV2/8 vectors encoding a pair of ZFNs and a hIDS cDNA donor were administered systemically in MPS II mice. Supraphysiological, vector dose-dependent levels of IDS enzyme were observed in the circulation and peripheral organs of ZFN+donor-treated mice. GAG contents were markedly reduced in tissues from all ZFN+donor-treated groups. Surprisingly, we also demonstrate that ZFN-mediated genome editing prevented the development of neurocognitive deficit in young MPS II mice (6-9 weeks old) treated at high vector dose levels. We conclude that this ZFN-based platform for expression of therapeutic proteins from the albumin locus is a promising approach for treatment of MPS II and other lysosomal diseases.

Mutations identified in a cohort of Mexican patients with lysosomal acid lipase deficiency.

INTRODUCTION AND OBJECTIVES: Lysosomal acid lipase deficiency (LAL-D) is an autosomal recessive disease caused by mutations in the LIPA gene, located on the long arm of chromosome 10 (10q23.31). Up until now, more than 59 mutations have been described and which are the cause of a very wide clinical spectrum. The goal of this study was to identify the mutations present in Mexican pediatric patients with a diagnosis of LAL-D. MATERIALS AND METHODS: A cross-sectional study was carried out which included all the pediatric patients with LAL-D treated in a tertiary hospital in Mexico from January 2000 to June 2017. RESULTS: Sixteen patients with LAL-D were identified with a disease phenotype marked by the accumulation of cholesteryl esters. Eight distinct variants in the LIPA gene sequence were found, four pathogenic variants and four probably pathogenic. In six individuals, the variants were found in the homozygous state and ten were compound heterozygous. The eight variants were inverted, with five found on exon 4 and the others on exons 2, 8 and 10. The variant c.386A>G;p.His129Arg was the most common, being found in six of the 16 individuals (37.5%), making it much more frequent than what had previously been reported in the literature in proportion to the rest of the variants. The mutation known as E8SJM, which has been the mostly frequently found at the international level, was not the most common among this group of Mexican patients. In conclusion, Mexican patients present a different frequency of mutations associated with LAL-D in comparison to European populations.

RTB lectin-mediated delivery of lysosomal α-l-iduronidase mitigates disease manifestations systemically including the central nervous system.

Mucopolysaccharidosis type I (MPS I) is a lysosomal disease resulting from deficiency in the α-L-iduronidase (IDUA) hydrolase and subsequent accumulation of glycosaminoglycan (GAG). Clinically, enzyme replacement therapy (ERT) with IDUA achieves negligible neurological benefits presumably due to blood-brain-barrier (BBB) limitations. To investigate the plant lectin ricin B chain (RTB) as a novel carrier for enzyme delivery to the brain, an IDUA:RTB fusion protein (IDUAL), produced in N. benthamiana leaves, was tested in a murine model of Hurler syndrome (MPS I). Affect mice (n=3 for each group) were intravenously injected with a single dose of IDUAL (0.58, 2 or 5.8mgIDUAequivalents/kg) and analyzed after 24h. IDUA activities in liver, kidney and spleen increased significantly, and liver GAG levels were significantly reduced in all three groups. Plasma IDUA levels for all treated groups were high at 1h after injection and decreased by 95% at 4h, indicating efficient distribution into tissues. For long-term evaluations, IDUAL (0.58 or 2mg/kg, 8 weekly injections) was intravenously injected into MPS I mice (n=12 for each group). Thirteen days after the 8th injection, significant IDUA activity was detected in the liver and spleen. GAG levels in tissues including the brain cortex and cerebellum were significantly reduced in treated animals. Treated MPS I mice also showed significant improvement in neurocognitive testing. ELISA results showed that while there was a significant antibody response against IDUAL and plant-derived IDUA, there was no significant antibody response to RTB. No major toxicity or adverse events were observed. Together, these results showed that infusion of IDUAL allowed for significant IDUA levels and GAG reduction in the brain and subsequent neurological benefits. This RTB-mediated delivery may have significant implications for therapeutic protein delivery impacting a broad spectrum of lysosomal, and potentially neurological diseases.

A Novel Approach to the Treatment of Plasma Protein Deficiency: Ex Vivo-Manipulated Adipocytes for Sustained Secretion of Therapeutic Proteins.

Despite the critical need for lifelong treatment of inherited and genetic diseases, there are no developmental efforts for most such diseases due to their rarity. Recent progress in gene therapy, including the approvals of two products (Glybera and Strimvelis) that may provide patients with sustained effects, has shed light on the development of gene therapy products. Most gene therapy products are based on either adeno-associated virus-mediated in vivo gene transfer to target tissues or administration of ex vivo gene-transduced hematopoietic cells. In such circumstances, there is room for different approaches to provide clinicians with other therapeutic options through a variety of principles based on studies not only to gain an understanding of the pathological mechanisms of diseases, but also to understand the physiological functions of target tissues and cells. In this review, we summarize recent progress in gene therapy-mediated enzyme replacement and introduce a different approach using adipocytes to enable lifelong treatment for intractable plasma protein deficiencies.

A simple method for quantification of plasma globotriaosylsphingosine: Utility for Fabry disease.

Fabry disease (FD) results from impaired globotriaosylceramide (Gb3) catabolism, due to a deficiency of the lysosomal hydrolase, α-galactosidase A (α-GalA). As a direct consequence, the deacetylated derivative, globotriaosylsphingosine (lyso-Gb3), is produced and contemporary evidence exemplifies its use as a biomarker. Here we developed a simple method to enable quantification of lyso-Gb3 in just 0.01mL of plasma and explored its concentration in a cohort of 73 Australian FD patients, as well as in individuals with other sphingolipidoses. In 2000 patients without FD, but with related metabolic conditions, lyso-Gb3 returned concentrations of <5pmol/mL. In the FD cohort, 53/60 patients with classical mutations returned lyso-Gb3 concentrations≥5pmol/mL whereas only 4/13 patients with "late-onset" mutations had lyso-Gb3≥5pmol/mL. Five females with normal α-GalA activity and genetically confirmed FD returned lyso-Gb3≥5pmol/mL. The prevalence of clinically significant disease including cardiomyopathy, nephropathy and cerebrovascular disease was congruent with higher lyso-Gb3 concentrations. Repeat testing was available for 51 patients-26 undergoing enzyme replacement therapy-and concentrations of lyso-Gb3 remained unaltered throughout 6-18 months independent of sex, mutation or treatment status. Our data suggest that the optimum use of lyso-Gb3 resides in laboratory confirmation of classical FD and for monitoring at least the initial response to therapeutic intervention. There is no evidence that lyso-Gb3 can inform on clinical events.

Role of LIMP-2 in the intracellular trafficking of ß-glucosidase in different human cellular models.

Acid ß-glucosidase (GCase), the enzyme deficient in Gaucher disease (GD), is transported to lysosomes by the lysosomal integral membrane protein (LIMP)-2. In humans, LIMP-2 deficiency leads to action myoclonus-renal failure (AMRF) syndrome. GD and AMRF syndrome share some clinical features. However, they are different from clinical and biochemical points of view, suggesting that the role of LIMP-2 in the targeting of GCase would be different in different tissues. Besides, the role of LIMP-2 in the uptake and trafficking of the human recombinant (hr)GCase used in the treatment of GD is unknown. Thus, we compared GCase activity and intracellular localization in immortalized lymphocytes, fibroblasts, and a neuronal model derived from multipotent adult stem cells, from a patient with AMRF syndrome, patients with GD, and control subjects. In fibroblasts and neuronlike cells, GCase targeting to the lysosomes is completely dependent on LIMP-2, whereas in blood cells, GCase is partially targeted to lysosomes by a LIMP-2-independent mechanism. Although hrGCase cellular uptake is independent of LIMP-2, its trafficking to the lysosomes is mediated by this receptor. These data provide new insights into the mechanisms involved in the intracellular trafficking of GCase and in the pathogeneses of GD and AMRF syndrome.