Enzyme-replacement therapy in mucopolysaccharidosis I

Delivery of an enzyme-IGFII fusion protein to the mouse brain is therapeutic for mucopolysaccharidosis type IIIB

Mucopolysaccharidosis type IIIB (MPS IIIB, Sanfilippo syndrome type B) is a lysosomal storage disease characterized by profound intellectual disability, dementia, and a lifespan of about two decades. The cause is mutation in the gene encoding α-N-acetylglucosaminidase (NAGLU), deficiency of NAGLU, and accumulation of heparan sulfate. Impediments to enzyme replacement therapy are the absence of mannose 6-phosphate on recombinant human NAGLU and the blood-brain barrier. To overcome the first impediment, a fusion protein of recombinant NAGLU and a fragment of insulin-like growth factor II (IGFII) was prepared for endocytosis by the mannose 6-phosphate/IGFII receptor. To bypass the blood-brain barrier, the fusion protein ("enzyme") in artificial cerebrospinal fluid ("vehicle") was administered intracerebroventricularly to the brain of adult MPS IIIB mice, four times over 2 wk. The brains were analyzed 1-28 d later and compared with brains of MPS IIIB mice that received vehicle alone or control (heterozygous) mice that received vehicle. There was marked uptake of the administered enzyme in many parts of the brain, where it persisted with a half-life of approximately 10 d. Heparan sulfate, and especially disease-specific heparan sulfate, was reduced to control level. A number of secondary accumulations in neurons [β-hexosaminidase, LAMP1(lysosome-associated membrane protein 1), SCMAS (subunit c of mitochondrial ATP synthase), glypican 5, β-amyloid, P-tau] were reduced almost to control level. CD68, a microglial protein, was reduced halfway. A large amount of enzyme also appeared in liver cells, where it reduced heparan sulfate and β-hexosaminidase accumulation to control levels. These results suggest the feasibility of enzyme replacement therapy for MPS IIIB.

Early treatment is associated with improved cognition in Hurler syndrome

OBJECTIVE

Hurler syndrome is the most clinically severe form of an autosomal recessive lysosomal disorder characterized by the deficiency of α-L-iduronidase. The resulting accumulation of glycosaminoglycans causes progressive multisystem deterioration, resulting in death in childhood. Umbilical cord blood transplantation from unrelated donors has been previously shown to improve neurological outcomes of children <2 years of age and prolong life. The purpose of this article is to determine whether age at transplantation can predict cognitive outcomes.

METHODS

Between June 1997 and February 2013, 31 patients with Hurler syndrome underwent umbilical cord blood transplantation and were evaluated at baseline and every 6 to 12 months thereafter. All 31 patients underwent complete neurodevelopmental evaluation (median follow-up = 7.3 years, range = 2-21.7) and a median of 7.0 evaluations (range = 3-18).

RESULTS

Younger age at transplantation was associated with improved cognitive function (p = 0.001), receptive and expressive language (p = 0.004 and p = 0.01), and adaptive behavior (p = 0.03).

INTERPRETATION

Early age at transplantation is a strong predictor of cognitive, language, and adaptive behavior outcomes. Children younger than 9 months at the time of transplant showed normal cognitive development. Our results demonstrate that early diagnosis is necessary for optimal outcomes and support the need for newborn screening, because most patients are not identified at this young age.

The role of microglia in human disease: therapeutic tool or target?

Microglia have long been the focus of much attention due to their strong proliferative response (microgliosis) to essentially any kind of damage to the CNS. More recently, we reached the realization that these cells play specific roles in determining progression and outcomes of essentially all CNS disease. Thus, microglia has ceased to be viewed as an accessory to underlying pathologies and has now taken center stage as a therapeutic target. Here, we review how our understanding of microglia's involvement in promoting or limiting the pathogenesis of diseases such as amyotrophic lateral sclerosis, Alzheimer's disease, Huntington's disease, multiple sclerosis, X-linked adrenoleukodystrophy (X-ALD) and lysosomal storage diseases (LSD) has changed over time. While strategies to suppress the deleterious and promote the virtuous functions of microglia will undoubtedly be forthcoming, replacement of these cells has already proven its usefulness in a clinical setting. Over the past few years, we have reached the realization that microglia have a developmental origin that is distinct from that of bone marrow-derived myelomonocytic cells. Nevertheless, microglia can be replaced, in specific situations, by the progeny of hematopoietic stem cells (HSCs), pointing to a strategy to engineer the CNS environment through the transplantation of modified HSCs. Thus, microglia replacement has been successfully exploited to deliver therapeutics to the CNS in human diseases such as X-ALD and LSD. With this outlook in mind, we will discuss the evidence existing so far for microglial involvement in the pathogenesis and the therapy of specific CNS disease.

Discovery and Clinical Development of Idursulfase (Elaprase®) for the Treatment of Mucopolysaccharidosis II (Hunter Syndrome)

Mucopolysaccharidosis II (MPS II), also known as Hunter syndrome, is a rare X-linked recessive lysosomal storage disorder with an incidence of 1 in 100 000 to 160 000 live births. The clinical disease is caused by a deficiency of iduronate-2-sulfatase, which results in a chronic and progressive accumulation of glycosaminoglycans or GAGs in nearly all cell types, tissues and organs of the body. Clinical manifestations of MPS II disease include airway obstruction and compromised lung capacity, cardiomyopathy and valvular heart disease, hepatosplenomegaly, severe skeletal deformities, and neurological decline in most patients. The lack of an effective treatment and the successes of enzyme replacement therapies (ERTs) for other lysosomal storage diseases motivated the development of an ERT for MPS II. Iduronate-2-sulfatase (idursulfase) was produced by recombinant DNA technology in a fully human protein production system which, importantly, resulted in the production of idursulfase with human glycosylation. The non-clinical development of idursulfase progressed from proof-of-principle pharmacodynamic studies, to dose and dose-frequency studies, to an analysis of tissue biodistribution of the enzyme, and finally to pharmacokinetic and toxicological assessments. The clinical development of the final drug product, called Elaprase® (Shire Human Genetic Therapies, Inc., Lexington, MA), consisted of an initial Phase I/II study, followed by a Phase II/III pivotal trial. The results of the Phase II/III showed that intravenous infusions of Elaprase were generally well tolerated, and that a weekly dosing regimen provided significant clinical benefit to MPS II patients as demonstrated by improvements in walking ability and pulmonary function. Elaprase received marketing authorisation in the USA in 2006 and in Europe in 2007. During this era, the development of Elaprase as an effective therapy for MPS II patients, was part of a continuum of many important scientific and medical advances in the field of rare genetic diseases.

Assessment of musculoskeletal abnormalities in children with mucopolysaccharidoses using pGALS

BACKGROUND

Children with mucopolysaccharidoses (MPS) often have musculoskeletal (MSK) abnormalities. Paediatric Gait, Arms, Legs, and Spine (pGALS), is a simple MSK assessment validated in school-age children to detect abnormal joints. We aimed to identify MSK abnormalities in children with MPS performing pGALS.

METHODS

Videos of children with a spectrum of MPS performing pGALS were analysed. A piloted proforma to record abnormalities for each pGALS manoeuvre observed in the videos (scored as normal/abnormal/not assessable) was used by three observers blinded to MPS subtype. Videos were scored independently and rescored for intra- and inter-observer consistency. Data were pooled and analysed.

RESULTS

Eighteen videos of children [12 boys, 6 girls, median age 11 years (4-19)] with MPS (13 type I [5 Hurler, 8 attenuated type I]; 4 type II; 1 mannosidosis) were assessed. The most common abnormalities detected using pGALS were restrictions of the shoulder, elbow, wrist, jaw (>75% cases), and fingers (2/3 cases). Mean intra-observer Κ 0.74 (range 0.65-0.88) and inter-observer Κ 0.62 (range 0.51-0.77). Hip manoeuvres were not clearly demonstrated in the videos.

CONCLUSIONS

In this observational study, pGALS identifies MSK abnormalities in children with MPS. Restricted joint movement (especially upper limb) was a consistent finding. Future work includes pGALS assessment of the hip and testing pGALS in further children with attenuated MPS type I. The use of pGALS and awareness of patterns of joint involvement may be a useful adjunct to facilitate earlier recognition of these rare conditions and ultimately access to specialist care.

Unresolving short stature in a possible case of mucopolysccharidosis

We present a metabolic disorder with main complaints of unresolving short stature following prolonged treatment for rickets. ES is a 4-year-old male who first presented to our hospital on self-referral but had been seen previously at another tertiary health facility. The complaints were a swelling on the back and poor growth since 1 year of age with associated skeletal deformities: Chest wall, wrists, knees and ankle joints, which were progressive. Examination revealed a severely stunted child with a large head and caput quadratum, craniofacial disproportion, coarse facial features, saddle-shaped nose, thick lips and bilateral corneal clouding/opacities. He had very poor language development for his age. His diagnoses based on clinical and radiological assessment was in keeping with Hurlers type of mucopolysaccharidoses. We highlight this case to emphasize the need for early consideration of other possible rare differential diagnoses in metabolic conditions in children.

Laronidase replacement therapy and left ventricular function in mucopolysaccharidosis I

We assessed the effects of long-term laronidase replacement therapy (LRT) on the left ventricular (LV) function of a 52-year-old adult woman with mucopolysaccharidosis I (MPS I). The urinary uronic acid concentration significantly decreased by 78.7% (from 75 to 16 mg/g creatinine) after LRT; thereafter, estimated LV weight as assessed by two-dimensional (2D) echocardiography significantly decreased by 33.3% (from 189 to 126 g). Although systolic LV function of the ejection fraction as assessed by 2D echocardiogram did not change after LRT, the diastolic LV function parameters of the deceleration time (DcT) and the ratio of early (E) to late (A) ventricular filling velocities (E/A ratio) significantly improved. The DcT significantly decreased from 355 to 300 ms and the E/A ratio significantly decreased from 1.8 to 0.98. These diastolic parameters were normalized. In the contraction synchrony assessed by 2D speckle tracking imaging, the maximum time delay of contraction decreased from 148 to 14 ms. In addition, the LV weight significantly correlated with the E/A ratio (p < 0.001, r = 0.63), DcT (p < 0.05, r = 0.48), and contraction synchrony (p < 0.001, r = 0.61), respectively. This is the first study to report that LRT significantly improves diastolic LV function and contraction synchrony in a patient with MPS I.

Hematopoietic stem cell transplantation effects on spinal cord compression in Hurler

Hurler syndrome type 1 (MPS-1) is an autosomal recessive lysosomal disorder due to the deficiency of the enzyme alpha-L-iduronidase which is necessary for the degradation of dermatan and heparan sulfate. It is characterized by deposit of glycosaminoglycans in tissues, progressive multisystem dysfunction, and early death. HSCT for children with MPS-I is effective, resulting in increased life expectancy and improvement of clinical parameters. The spinal MRI performed on a female 10 yr old undergoing HSCT at the age of 18 months and receiving ERT revealed a considerable decrease in soft tissue around the tip of odontoid causing a significant reduction in spinal cord compression. In light of this result, we suppose that combined ERT and HSCT are successful in Hurler I disease.

Perioperative complications in patients diagnosed with mucopolysaccharidosis and the impact of enzyme replacement therapy followed by hematopoietic stem cell transplantation at early age

BACKGROUND

Mucopolysaccharidoses (MPS) are hereditary storage diseases; airway management typically worsens in these patients with the progression of the disease.

OBJECTIVE(S)

To assess the incidence of perioperative complications in children with MPS and the impact of enzyme replacement therapy (ERT) followed by hematopoietic stem cell transplantation (HSCT).

METHODS

The records of patients with MPS treated with ERT followed by HSCT, who received anesthesia at the Wilhelmina Children's Hospital between 2003 and 2012, were reviewed. Data were collected on incidence of perioperative respiratory and cardiovascular complications and the impact of treatment and age.

RESULTS

Nineteen children with MPS were identified (including 17 Hurler patients), who received ERT treatment followed by HSCT. Median age at start of treatment was 14 (range: 7-43) months. Patients were anesthetized 136 times. The incidence of respiratory and cardiovascular complications was 24% and 4%, respectively. Airway management by face mask was difficult in 7%. There were no problems with the laryngeal mask airway. Tracheal intubation was difficult in 25% and failed in 10%; using a video laryngoscope was most successful (89%), followed by classic laryngoscope (67%) and fiber-optic scope (20%). Multivariate logistic regression analyses showed that the incidence of perioperative respiratory problems did not increase with age or decrease after start of treatment.

CONCLUSION

Perioperative airway management was most successful using a laryngeal mask airway or video laryngoscope. Treatment with ERT followed by HSCT and patient age did not influence the incidence of perioperative respiratory problems.

Insulin-like growth factor II peptide fusion enables uptake and lysosomal delivery of α-N-acetylglucosaminidase to mucopolysaccharidosis type IIIB fibroblasts

Enzyme replacement therapy for MPS IIIB (mucopolysaccharidosis type IIIB; also known as Sanfilippo B syndrome) has been hindered by inadequate mannose 6 phosphorylation and cellular uptake of rhNAGLU (recombinant human α-N-acetylglucosaminidase). We expressed and characterized a modified rhNAGLU fused to the receptor-binding motif of IGF-II (insulin-like growth factor 2) (rhNAGLU-IGF-II) to enhance its ability to enter cells using the cation-independent mannose 6-phosphate receptor, which is also the receptor for IGF-II (at a different binding site). RhNAGLU-IGF-II was stably expressed in CHO (Chinese-hamster ovary) cells, secreted and purified to apparent homogeneity. The Km and pH optimum of the fusion enzyme was similar to those reported for rhNAGLU. Both intracellular uptake and confocal microscopy suggested that MPS IIIB fibroblasts readily take up the fusion enzyme via receptor-mediated endocytosis that was inhibited significantly (P<0.001) by the monomeric IGF-II peptide. Glycosaminoglycan storage was reduced by 60% (P<0.001) to near background levels in MPS IIIB cells after treatment with rhNAGLU-IGF-II, with half-maximal correction at concentrations of 3-12 pM. A similar cellular uptake mechanism via the IGF-II receptor was also demonstrated in two different brain tumour-derived cell lines. Fusion of rhNAGLU to IGF-II enhanced its cellular uptake while maintaining enzymatic activity, supporting its potential as a therapeutic candidate for treating MPS IIIB.

Genistin-rich soy isoflavone extract in substrate reduction therapy for Sanfilippo syndrome: An open-label, pilot study in 10 pediatric patients

BACKGROUND

Mucopolysaccharidoses (MPSs) are a group of severe metabolic disorders caused by deficiencies in enzymes involved in the degradation of glycosaminoglycans (GAGs)-long chains of sugar carbohydrates in cells that help build bone, cartilage, tendons, corneas, skin, and connective tissue. Although enzyme replacement therapy has become available for the treatment of some types of MPS, effective treatment of neurodegenerative forms of MPS has yet to be determined. Recently, genistein (4',5,7-trihydroxyisoflavone), a specific inhibitor of protein tyrosine kinase, has been found to inhibit GAG synthesis and to reduce GAG concentrations in cultures of fibroblasts of MPS patients. Therefore, a potential substrate reduction therapy has been proposed.

OBJECTIVE

The aim of this study was to examine urinary GAG concentration, hair morphology, and cognitive function in patients receiving genistin treatment for Sanfilippo syndrome (MPS type III).

METHODS

Patients aged 3 to 14 years with a biochemically confirmed diagnosis of MPS IIIA or MPS IIIB were eligible to enroll in this open-label, pilot study. Genistin-rich soy isoflavone extract 5 mg/kg/d was administered PO for 12 months. Urinary GAG concentration, hair morphology,and cognitive function (measured using a modified version of the Brief Assessment Examination [BAE] and parent observations)were measured at baseline and after 12 months of treatment.

RESULTS

Ten patients (6 girls, 4 boys; mean age, 8 years [range,3\2-14 years];mean weight, 28 kg [range, 17\2-43 kg]) were included in the study. All patients had Sanfilippo syndrome; 5 patients had MPS IIIA and 5 had MPS IIIB. After 1 year, statistically significant improvement was found in urinary GAG concentration, hair morphology, and cognitive function. Urinary GAG concentration decreased significantly in all 5 patients with MPS IIIA and in 2 patients with MPS IIIB (P = 0.028). Hair morphology improved significantly in all 5 MPS IIIA patients and in 3 MPS IIIB patients (P = 0.012). A significant increase in the BAE score (by 2-6 points) was noted in 8 patients, while the scores of 2 patients did not change after 12 months of treatment (P = 0.012). No adverse events (AEs) considered related to treatment were reported. Moreover, no AEs not related to the treatment (apart from classical symptoms of MPS III) were noted.

CONCLUSIONS

This pilot study found some improvements in GAG concentration, hair morphology, and cognitive function in these pediatric patients with Sanfilippo syndrome treated with genistin-rich soy isoflavone extract for 1 year. Clinical trials are needed to evaluate the efficacy and safety of this potential treatment.

[Hurler syndrome: early diagnosis and treatment]

Hurler syndrome, the most severe form of mucopolysaccharidosis type I (MPS I), is a rare lysosomal storage disease. The overall incidence of MPS I is 0.99-1.99/100,000 live births. Accumulation of glycosaminoglycans causes the progressive dysfunction of multiple organs. We report the case of a 3-week-old newborn who was hospitalized in the Neonatal Intensive Care Unit for feeding problems. Coarse facial features and gingival hypertrophy, associated with axial hypotonia, upper airway obstruction, and moderate hepatomegaly, led to the early diagnosis of MPS I at 3 weeks of age and was confirmed by an abnormally elevated amount of dermatan and heparan sulphate in the urine and complete deficiency of alpha-L-iduronidase lysosomal enzyme activity. The child was homozygous for the p.W402X mutation, located on chromosome 4p16.3 of the alpha-L-iduronidase (IDUA) gene. The clinical condition gradually deteriorated until the age of 4 months, with thoracic and lumbar dysostoses, glaucoma, cerebral ventricular dilatation and cervical spinal stenosis, dilated cardiomyopathy, and umbilical hernia. Early diagnosis allowed enzyme replacement therapy (iaronidase, Aldurazyme(®), Genzyme) started at the age of 5 months, which provided stabilization of the heart disease, significant regression of rhinologic symptoms, and regression of hepatomegaly. Cord blood hematopoietic stem cell transplantation was performed at 11 months of age, allowing optimal preservation of cognitive development.

The natural history of MPS I: global perspectives from the MPS I Registry

Purpose:

In this study, we aimed to describe the natural history of mucopolysaccharidosis I.

Methods:

Data from 1,046 patients who enrolled in the MPS I Registry as of August 2013 were available for descriptive analysis. Only data from untreated patients and data prior to treatment for patients who received treatment were considered. Age at symptom onset, diagnosis, and treatment initiation were examined by geographic region and phenotype (from most to least severe: Hurler, Hurler–Scheie, and Scheie). For each symptom, frequency and age at onset were examined.

Results:

Natural history data were available for 987 patients. Most patients were from Europe (45.5%), followed by North America (34.8%), Latin America (17.3%), and Asia Pacific (2.4%). Phenotype distribution was 60.9% for Hurler, 23.0% for Hurler–Scheie, and 12.9% for Scheie (3.2% undetermined) syndromes. Median age at symptom onset for Hurler, Hurler–Scheie, and Scheie syndromes was 6 months, 1.5 years, and 5.3 years, respectively; median age at treatment initiation was 1.5 years, 8.0 years, and 16.9 years, respectively. Coarse facial features and corneal clouding were among the most common symptoms in all three phenotypes.

Conclusion:

A delay between symptom onset and treatment exists, especially in patients with attenuated mucopolysaccharidosis I. A better understanding of disease manifestations may help facilitate prompt diagnosis and treatment and improve patient outcomes.

Mesenchymal stem cells do not prevent antibody responses against human α-L-iduronidase when used to treat mucopolysaccharidosis type I

Mucopolysaccharidosis type I (MPSI) is an autosomal recessive disease that leads to systemic lysosomal storage, which is caused by the absence of α-L-iduronidase (IDUA). Enzyme replacement therapy is recognized as the best therapeutic option for MPSI; however, high titers of anti-IDUA antibody have frequently been observed. Due to the immunosuppressant properties of MSC, we hypothesized that MSC modified with the IDUA gene would be able to produce IDUA for a long period of time. Sleeping Beauty transposon vectors were used to modify MSC because these are basically less-immunogenic plasmids. For cell transplantation, 4×10⁶ MSC-KO-IDUA cells (MSC from KO mice modified with IDUA) were injected into the peritoneum of KO-mice three times over intervals of more than one month. The total IDUA activities from MSC-KO-IDUA before cell transplantation were 9.6, 120 and 179 U for the first, second and third injections, respectively. Only after the second cell transplantation, more than one unit of IDUA activity was detected in the blood of 3 mice for 2 days. After the third cell transplantation, a high titer of anti-IDUA antibody was detected in all of the treated mice. Anti-IDUA antibody response was also detected in C57Bl/6 mice treated with MSC-WT-IDUA. The antibody titers were high and comparable to mice that were immunized by electroporation. MSC-transplanted mice had high levels of TNF-alpha and infiltrates in the renal glomeruli. The spreading of the transplanted MSC into the peritoneum of other organs was confirmed after injection of ¹¹¹In-labeled MSC. In conclusion, the antibody response against IDUA could not be avoided by MSC. On the contrary, these cells worked as an adjuvant that favored IDUA immunization. Therefore, the humoral immunosuppressant property of MSC is questionable and indicates the danger of using MSC as a source for the production of exogenous proteins to treat monogenic diseases.

Comparative study on mannose 6-phosphate residue contents of recombinant lysosomal enzymes

As most recombinant lysosomal enzymes are incorporated into cells via mannose 6-phosphate (M6P) receptors, the M6P content is important for effective enzyme replacement therapy (ERT) for lysosomal diseases. However, there have been no comprehensive reports of the M6P contents of lysosomal enzymes. We developed an M6P assay method comprising three steps, i.e., acid hydrolysis of glycoproteins, derivatization of M6P, and high-performance liquid chromatography, and determined the M6P contents of six recombinant lysosomal enzymes now available for ERT and one in the process of development. The assay is easy, specific, and reproducible. The results of the comparative study revealed that the M6P contents of agalsidase alfa, agalsidase beta, modified α-N-acetylgalactosaminidase, alglucosidase alfa, laronidase, idursulfase, and imiglucerase are 2.1, 2.9, 5.9, 0.7, 2.5, 3.2, and <0.3 mol/mol enzyme, respectively. The results were correlated with those of the biochemical analyses previously performed and that of the binding assay of exposed M6P of the enzymes with the domain 9 of the cation-independent M6P receptor. This assay method is useful for comparison of the M6P contents of recombinant lysosomal enzymes for ERT.

Emerging principles for the therapeutic exploitation of glycosylation

Glycosylation plays a key role in a wide range of biological processes. Specific modification to a glycan's structure can directly modulate its biological function. Glycans are not only essential to glycoprotein folding, cellular homeostasis, and immune regulation but are involved in multiple disease conditions. An increased molecular and structural understanding of the mechanistic role that glycans play in these pathological processes has driven the development of therapeutics and illuminated novel targets for drug design. This knowledge has enabled the treatment of metabolic disorders and the development of antivirals and shaped cancer and viral vaccine strategies. Furthermore, an understanding of glycosylation has led to the development of specific drug glycoforms, for example, monoclonal antibodies, with enhanced potency.

Central nervous system delivery of helper-dependent canine adenovirus corrects neuropathology and behavior in mucopolysaccharidosis type VII mice

Canine adenovirus type 2 vectors (CAV-2) are promising tools to treat global central nervous system (CNS) disorders because of their preferential transduction of neurons and efficient retrograde axonal transport. Here we tested the potential of a helper-dependent CAV-2 vector expressing β-glucuronidase (HD-RIGIE) in a mouse model of mucopolysaccharidosis type VII (MPS VII), a lysosomal storage disease caused by deficiency in β-glucuronidase activity. MPS VII leads to glycosaminoglycan accumulation into enlarged vesicles in peripheral tissues and the CNS, resulting in peripheral and neuronal dysfunction. After intracranial administration of HD-RIGIE, we show long-term expression of β-glucuronidase that led to correction of neuropathology around the injection site and in distal areas. This phenotypic correction correlated with a decrease in secondary-elevated lysosomal enzyme activity and glycosaminoglycan levels, consistent with global biochemical correction. Moreover, HD-RIGIE-treated mice show significant cognitive improvement. Thus, injections of HD-CAV-2 vectors in the brain allow a global and sustained expression and may have implications for brain therapy in patients with lysosomal storage disease.

Long-term therapeutic efficacy of allogenic bone marrow transplantation in a patient with mucopolysaccharidosis IVA

Mucopolysaccharidosis IVA (MPS IVA) is one of the lysosomal storage diseases. It is caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase. Deficiency of this enzyme leads to accumulation of the specific glycosaminoglycans keratan sulfate and chondroitin-6-sulfate. This accumulation has a direct impact on cartilage and bone development, resulting in systemic skeletal dysplasia. There is no curative therapy for this skeletal dysplasia. This report describes long-term therapeutic efficacy in a 15-year-old boy with a severe form of MPS IVA who received successful allogeneic bone marrow transplantation (BMT) from his HLA-identical carrier sister. The level of the GALNS enzyme in the recipient's lymphocytes reached almost half of normal level within two years after BMT. For the successive 9+ years post-BMT, GALNS activity in his lymphocytes maintained the same level as the donor's, and the level of urinary uronic acid was reduced. Lumbar bone mineral density increased around 50% one year later post-BMT and was kept consistent. Radiographs showed that the figures of trochanter major and minor appeared, while the epiphyseal dysplasia in the femoral cap was almost unchanged. Loud snoring and apnea disappeared. Vital capacity increased to around 20% for the first two years and was maintained. Activity of daily life (ADL) was improved in work/study efficacy, respiratory status, sleep, joint pain, and frequency of infection. In conclusion, the long-term study of hematopoetic stem cell transplantation has shown clinical improvements in respiratory function, radiograph findings, ADL, and biochemical findings, suggesting that it is a potential therapeutic option for patients with MPS IVA.

Craniovertebral junction pathological features and their management in the mucopolysaccharidoses

The mucopolysaccharidoses (MPS) are multisystemic inherited metabolic diseases caused by the deficiency of the enzymes involved in the degradation of glycosaminoglycans (GAGs), which variably involve the central nervous system, heart, lungs, and bones.Undegraded or only partly degraded GAGs accumulate in the extracellular matrix, joint fluid, and connective tissue leading to widespread tissue and organ dysfunction.The introduction of hematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy (ERT) has positively affected the natural history of MPS patients and their life expectancy. However, the presence of spinal abnormalities and deposition of GAGs in soft tissues remains nearly unaltered.Abnormalities of the craniovertebral junction (CVJ) and GAG deposits can result in spinal cord compression with slowly progressive myelopathy or acute posttraumatic tetraplegia.The current paper discusses neuroimaging findings in a consecutive series of 42 MPS patients followed at our Center for Metabolic Diseases and their neurosurgical issues.Current recommendations for decompression and fusion will be discussed according to our experience and review of the literature.

Immune response to intrathecal enzyme replacement therapy in mucopolysaccharidosis I patients

BACKGROUND

Intrathecal (IT) enzyme replacement therapy with recombinant human α-L-iduronidase (rhIDU) has been studied to treat glycosaminoglycan storage in the central nervous system of mucopolysaccharidosis (MPS) I dogs and is currently being studied in MPS I patients.

METHODS

We studied the immune response to IT rhIDU in MPS I subjects with spinal cord compression who had been previously treated with intravenous rhIDU. We measured the concentrations of specific antibodies and cytokines in serum and cerebrospinal fluid (CSF) collected before monthly IT rhIDU infusions and compared the serologic findings with clinical adverse event (AE) reports to establish temporal correlations with clinical symptoms.

RESULTS

Five MPS I subjects participating in IT rhIDU trials were studied. One subject with symptomatic spinal cord compression had evidence of an inflammatory response with CSF leukocytosis, elevated interleukin-5, and elevated immunoglobulin G. This subject also complained of lower back pain and buttock paresthesias temporally correlated with serologic abnormalities. Clinical symptoms were managed with oral medication, and serologic abnormalities were resolved, although this subject withdrew from the trial to have spinal decompressive surgery.

CONCLUSION

IT rhIDU was generally well tolerated in the subjects studied, although one subject had moderate to severe clinical symptoms and serologic abnormalities consistent with an immune response.

Enzyme replacement therapy with laronidase (Aldurazyme(®)) for treating mucopolysaccharidosis type I

BACKGROUND

Mucopolysaccharidosis type I can be classified as three clinical sub-types; Hurler syndrome, Hurler-Scheie syndrome and Scheie syndrome, with the scale of severity being such that Hurler syndrome is the most severe and Scheie syndrome the least severe. It is a rare, autosomal recessive disorder caused by a deficiency of alpha-L-iduronidase. Deficiency of this enzyme results in the accumulation of glycosaminoglycans within the tissues. The clinical manifestations are facial dysmorphism, hepatosplenomegaly, upper airway obstruction, skeletal deformity and cardiomyopathy. If Hurler syndrome is left untreated, death ensues by adolescence. There are more attenuated variants termed Hurler-Scheie or Scheie syndrome, with those affected potentially not presenting until adulthood. Enzyme replacement therapy has been used for a number of years in the treatment of Hurler syndrome, although the current gold standard would be a haemopoietic stem cell transplant in those diagnosed by 2.5 years of age.

OBJECTIVES

To evaluate the effectiveness and safety of treating mucopolysaccharidosis type I with laronidase enzyme replacement therapy as compared to placebo.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Inborn Errors of Metabolism Trials Register, MEDLINE via OVID and EMBASE.Date of most recent search: 08 February 2013.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of laronidase enzyme replacement therapy compared to placebo.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the identified trials. The authors then appraised and extracted data.

MAIN RESULTS

One study of 45 patients met the inclusion criteria. This double-blind, placebo-controlled, randomised, multinational trial looked at laronidase at a dose of 0.58 mg/kg/week versus placebo in patients with mucopolysaccharidosis type I. All primary outcomes listed in this review were studied in this trial. The laronidase group achieved statistically significant improvements in per cent predicted forced vital capacity compared to placebo, MD 5.60 (95% confidence intervals 1.24 to 9.96) and in the six-minute-walk test (mean improvement of 38.1 metres in the laronidase group; P = 0.039, when using a prospectively planned analysis of covariance). The levels of urinary glycoaminoglycans were also significantly reduced. In addition, there were improvements in hepatomegaly, sleep apnoea and hypopnoea. Laronidase antibodies were detected in nearly all patients in the treatment group with no apparent clinical effect and titres were reducing by the end of the study. Infusion-related adverse reactions occurred in both groups but all were mild and none necessitated medical intervention or infusion cessation.

AUTHORS' CONCLUSIONS

The current evidence demonstrates that laronidase is effective when compared to placebo in the treatment of mucopolysaccharidosis type I. The included trial was comprehensive and of good quality, although there were few participants. The trial included all of the key outcome measures we wished to look at. It demonstrated that laronidase is efficacious in relation to reducing biochemical parameters (reduced urine glycosaminoglycan excretion) and improved functional capacity as assessed by forced vital capacity and the six-minute-walk test. In addition glycosaminoglycan storage was reduced as ascertained by a reduction in liver volume. Laronidase appeared to be safe and, while antibodies were generated, these titres were reducing by the end of the study. More studies are required to determine long-term effectiveness and safety and to assess the impact upon quality of life. Enzyme replacement therapy with laronidase can be used pre- and peri-haemopoietic stem cell transplant, which is now the gold standard treatment in those patients diagnosed under 2.5 years of age.

Therapies of mucopolysaccharidosis IVA (Morquio A syndrome)

INTRODUCTION

Morquio A syndrome (mucopolysaccharidosis type IVA, MPS IVA) is one of the lysosomal storage diseases and is caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS). Deficiency of this enzyme leads to accumulation of glycosaminoglycans (GAGs), keratan sulfate (KS) and chondroitin-6-sulfate (C6S). The majority of KS is produced by chondrocytes, and therefore, the undegraded substrates accumulate mainly in cells and extracelluar matrix (ECM) of cartilage. This has a direct impact on cartilage and bone development, leading to systemic skeletal dysplasia. In patients with Morquio A, cartilage cells are vacuolated, and this results in abnormal chondrogenesis and/or endochondral ossification.

AREAS COVERED

This article describes the advanced therapies of Morquio A, focused on enzyme replacement therapy (ERT) and gene therapy to deliver the drug to avascular bone lesions. ERT and gene therapies for other types of MPS are also discussed, which provide therapeutic efficacy to bone lesions.

EXPERT OPINION

ERT, gene therapy and hematopietic stem therapy are clinically and/or experimentally conducted. However, there is no effective curative therapy for bone lesion to date. One of the limitations for Morquio A therapy is that targeting avascular cartilage tissues remains an unmet challenge. ERT or gene therapy with bone-targeting system will improve the bone pathology and skeletal manifestations more efficiently.

Enzyme replacement therapy with laronidase (Aldurazyme) for treating mucopolysaccharidosis type I

BACKGROUND

Mucopolysaccharidosis type I can be classified as three clinical sub-types; Hurler syndrome, Hurler-Scheie syndrome and Scheie syndrome, with the scale of severity being such that Hurler syndrome is the most severe and Scheie syndrome the least severe. It is a rare, autosomal recessive disorder caused by a deficiency of alpha-L-iduronidase. Deficiency of this enzyme results in the accumulation of glycosaminoglycans within the tissues. The clinical manifestations are facial dysmorphism, hepatosplenomegaly, upper airway obstruction, skeletal deformity and cardiomyopathy. If Hurler syndrome is left untreated, death ensues by adolescence. There are more attenuated variants termed Hurler-Scheie or Scheie syndrome, with those affected potentially not presenting until adulthood. Enzyme replacement therapy has been used for a number of years in the treatment of Hurler syndrome, although the current gold standard would be a haemopoietic stem cell transplant in those diagnosed by 2.5 years of age.

OBJECTIVES

To evaluate the effectiveness and safety of treating mucopolysaccharidosis type I with laronidase enzyme replacement therapy as compared to placebo.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Inborn Errors of Metabolism Trials Register, MEDLINE via OVID and EMBASE.Date of most recent search: 08 February 2013.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of laronidase enzyme replacement therapy compared to placebo.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the identified trials. The authors then appraised and extracted data.

MAIN RESULTS

One study of 45 patients met the inclusion criteria. This double-blind, placebo-controlled, randomised, multinational trial looked at laronidase at a dose of 0.58 mg/kg/week versus placebo in patients with mucopolysaccharidosis type I. All primary outcomes listed in this review were studied in this trial. The laronidase group achieved statistically significant improvements in per cent predicted forced vital capacity compared to placebo, MD 5.60 (95% confidence intervals 1.24 to 9.96) and in the six-minute-walk test (mean improvement of 38.1 metres in the laronidase group; P = 0.66, when using a prospectively planned analysis of covariance). The levels of urinary glycoaminoglycans were also significantly reduced. In addition, there were improvements in hepatomegaly, sleep apnoea and hypopnoea. Laronidase antibodies were detected in nearly all patients in the treatment group with no apparent clinical effect and titres were reducing by the end of the study. Infusion-related adverse reactions occurred in both groups but all were mild and none necessitated medical intervention or infusion cessation.

AUTHORS' CONCLUSIONS

The current evidence demonstrates that laronidase is effective when compared to placebo in the treatment of mucopolysaccharidosis type I. The included trial was comprehensive and of good quality, although there were few participants. The trial included all of the key outcome measures we wished to look at. It demonstrated that laronidase is efficacious in relation to reducing biochemical parameters(reduced urine glycosaminoglycan excretion) and improved functional capacity as assessed by forced vital capacity and the six-minute walk test. In addition glycosaminoglycan storage was reduced as ascertained by a reduction in liver volume. Laronidase appeared to be safe and, while antibodies were generated, these titres were reducing by the end of the study. More studies are required to determine long-term effectiveness and safety and to assess the impact upon quality of life. Enzyme replacement therapy with laronidase can be used pre- and peri-haemopoietic stem cell transplant, which is now the gold standard treatment in those patients diagnosed under 2.5 years of age.

A pilot newborn screening program for Mucopolysaccharidosis type I in Taiwan

BACKGROUND

Mucopolysaccharidosis type I (MPS I) is a genetic disease caused by the deficiency of α-L-iduronidase (IDUA) activity. MPS I is classified into three clinical phenotypes called Hurler, Scheie, and Hurler-Scheie syndromes according to their clinical severity. Treatments for MPS I are available. Better outcomes are associated with early treatment, which suggests a need for newborn screening for MPS I. The goal of this study was to determine whether measuring IDUA activity in dried blood on filter paper was effective in newborn screening for MPS I.

METHODS

We conducted a newborn screening pilot program for MPS I from October 01, 2008 to April 30, 2013. Screening involved measuring IDUA activity in dried blood spots from 35,285 newborns using a fluorometric assay.

RESULTS

Of the 35,285 newborns screened, 19 did not pass the tests and had been noticed for a recall examination. After completing further recheck process, 3 were recalled again for leukocyte IDUA enzyme activity testing. Two of the three had deficient leukocyte IDUA activity. Molecular DNA analyses confirmed the diagnosis of MPS I in these two newborns.

CONCLUSIONS

It is feasible to use the IDUA enzyme assay for newborn screening. The incidence of MPS I in Taiwan estimated from this study is about 1/17,643.

Enzyme replacement in neuronal storage disorders in the pediatric population

OPINION STATEMENT

In the past 15 years, for select lysosomal storage diseases, there has been a shift from symptom management to disease modification in terms of treatment strategy, mainly related to use of enzyme replacement therapy (ERT). Yet the application of ERT is for very few diseases, and while beneficial, ERT does not represent a cure. For some disorders, the advent of ERT has made a dramatic impact, while for others, benefits have been much more modest. Understanding of the long-term effects as well as the appropriate time for initiation of ERT is under exploration in a number of diseases, while the feasibility of ERT is still being established for others. No definite effects of ERT on central nervous system manifestations of lysosomal storage diseases have been observed for any disease to date. New strategies, including intrathecal enzyme replacement, gene therapy and substrate reduction therapy are being developed in animal models and clinical trials, which hopefully will begin a new era of nervous system disease modification in neuronal storage disorders.

Newborn screening and diagnosis of mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are caused by deficiency of lysosomal enzyme activities needed to degrade glycosaminoglycans (GAGs), which are long unbranched polysaccharides consisting of repeating disaccharides. GAGs include: chondroitin sulfate (CS), dermatan sulfate (DS), heparan sulfate (HS), keratan sulfate (KS), and hyaluronan. Their catabolism may be blocked singly or in combination depending on the specific enzyme deficiency. There are 11 known enzyme deficiencies, resulting in seven distinct forms of MPS with a collective incidence of higher than 1 in 25,000 live births. Accumulation of undegraded metabolites in lysosomes gives rise to distinct clinical syndromes. Generally, the clinical conditions progress if untreated, leading to developmental delay, systemic skeletal deformities, and early death. MPS disorders are potentially treatable with enzyme replacement therapy or hematopoietic stem cell transplantation. For maximum benefit of available therapies, early detection and intervention are critical. We recently developed a novel high-throughput multiplex method to assay DS, HS, and KS simultaneously in blood samples by using high performance liquid chromatography/tandem mass spectrometry for MPS. The overall performance metrics of HS and DS values on MPS I, II, and VII patients vs. healthy controls at newborns were as follows using a given set of cut-off values: sensitivity, 100%; specificity, 98.5-99.4%; positive predictive value, 54.5-75%; false positive rate, 0.62-1.54%; and false negative rate, 0%. These findings show that the combined measurements of these three GAGs are sensitive and specific for detecting all types of MPS with acceptable false negative/positive rates. In addition, this method will also be used for monitoring therapeutic efficacy. We review the history of GAG assay and application to diagnosis for MPS.

Human α-L-iduronidase uses its own N-glycan as a substrate-binding and catalytic module

N-glycosylation is a major posttranslational modification that endows proteins with various functions. It is established that N-glycans are essential for the correct folding and stability of some enzymes; however, the actual effects of N-glycans on their activities are poorly understood. Here, we show that human α-l-iduronidase (hIDUA), of which a dysfunction causes accumulation of dermatan/heparan sulfate leading to mucopolysaccharidosis type I, uses its own N-glycan as a substrate binding and catalytic module. Structural analysis revealed that the mannose residue of the N-glycan attached to N372 constituted a part of the substrate-binding pocket and interacted directly with a substrate. A deglycosylation study showed that enzyme activity was highly correlated with the N-glycan attached to N372. The kinetics of native and deglycosylated hIDUA suggested that the N-glycan is also involved in catalytic processes. Our study demonstrates a previously unrecognized function of N-glycans.

Residual α-L-iduronidase activity in fibroblasts of mild to severe Mucopolysaccharidosis type I patients

Three major clinical subgroups are usually distinguished in Mucopolysaccharidosis type I: Hurler (MPS IH, severe presentation), Hurler-Scheie (MPS IH/S, intermediate) and Scheie (MPS IS, mild). To facilitate treatment with hematopoietic stem-cell transplantation, early diagnosis is important for MPS IH patients. Although screening for MPS I in newborns would allow detection at an early age, it may be difficult to predict the phenotype on the basis of the genotype in these infants. Extra diagnostic tools are thus required. Based on the hypothesis that distinct MPS I phenotypes may result from differences in residual α-l-iduronidase (IDUA) activity, we modified the common IDUA assay using the substrate 4-methylumbelliferyl-α-l-iduronide to allow quantification of low IDUA activity in MPS I fibroblasts. Enzyme incubation was performed with high protein concentrations at different time points up to 8h. Mean residual IDUA activity was 0.18% (range 0-0.6) of the control value in MPS IH fibroblasts (n=5); against 0.27% (range 0.2-0.3) in MPS IH/S cells (n=3); and 0.79% (range 0.3-1.8) in MPS IS fibroblasts (n=5). These results suggest that residual IDUA activity and severity of the MPS I phenotype are correlated. Two MPS IS patients with rare (E276K/E276K) or indefinite (A327P/unknown) IDUA genotypes had residual IDUA activity in the MPS IS range, illustrating the usefulness of our approach. IDUA(E276K) was very unstable at 37°C, but more stable at 23°C, suggesting thermal instability. We conclude that this procedure for determining residual IDUA activity in fibroblasts of MPS I patients may be helpful to predict MPS I phenotype.

An algorithm to predict phenotypic severity in mucopolysaccharidosis type I in the first month of life

Introduction

Mucopolysaccharidosis type I (MPS I) is a progressive multisystem lysosomal storage disease caused by deficiency of the enzyme α-L-iduronidase (IDUA). Patients present with a continuous spectrum of disease severity, and the most severely affected patients (Hurler phenotype; MPS I-H) develop progressive cognitive impairment. The treatment of choice for MPS I-H patients is haematopoietic stem cell transplantation, while patients with the more attenuated phenotypes benefit from enzyme replacement therapy.

The potential of newborn screening (NBS) for MPS I is currently studied in many countries. NBS for MPS I, however, necessitates early assessment of the phenotype, in order to decide on the appropriate treatment. In this study, we developed an algorithm to predict phenotypic severity in newborn MPS I patients.

Methods

Thirty patients were included in this study. Genotypes were collected from all patients and all patients were phenotypically categorized at an age of > 18 months based on the clinical course of the disease. In 18 patients, IDUA activity in fibroblast cultures was measured using an optimized IDUA assay. Clinical characteristics from the first month of life were collected from 23 patients.

Results

Homozygosity or compound heterozygosity for specific mutations which are associated with MPS I-H, discriminated a subset of patients with MPS I-H from patients with more attenuated phenotypes (specificity 100%, sensitivity 82%). Next, we found that enzymatic analysis of IDUA activity in fibroblasts allowed identification of patients affected by MPS I-H. Therefore, residual IDUA activity in fibroblasts was introduced as second step in the algorithm. Patients with an IDUA activity of < 0.32 nmol x mg^-1 × hr^-1 invariably were MPS I-H patients, while an IDUA activity of > 0.66 nmol × mg^-1 × hr^-1 was only observed in more attenuated patients. Patients with an intermediate IDUA activity could be further classified by the presence of differentiating clinical characteristics, resulting in a model with 100% sensitivity and specificity for this cohort of patients.

Conclusion

Using genetic, biochemical and clinical characteristics, all potentially available in the newborn period, an algorithm was developed to predict the MPS I phenotype, allowing timely initiation of the optimal treatment strategy after introduction of NBS.

A rapid and sensitive method for measuring N-acetylglucosaminidase activity in cultured cells

A rapid and sensitive method to quantitatively assess N-acetylglucosaminidase (NAG) activity in cultured cells is highly desirable for both basic research and clinical studies. NAG activity is deficient in cells from patients with Mucopolysaccharidosis type IIIB (MPS IIIB) due to mutations in NAGLU, the gene that encodes NAG. Currently available techniques for measuring NAG activity in patient-derived cell lines include chromogenic and fluorogenic assays and provide a biochemical method for the diagnosis of MPS IIIB. However, standard protocols require large amounts of cells, cell disruption by sonication or freeze-thawing, and normalization to the cellular protein content, resulting in an error-prone procedure that is material- and time-consuming and that produces highly variable results. Here we report a new procedure for measuring NAG activity in cultured cells. This procedure is based on the use of the fluorogenic NAG substrate, 4-Methylumbelliferyl-2-acetamido-2-deoxy-alpha-D-glucopyranoside (MUG), in a one-step cell assay that does not require cell disruption or post-assay normalization and that employs a low number of cells in 96-well plate format. We show that the NAG one-step cell assay greatly discriminates between wild-type and MPS IIIB patient-derived fibroblasts, thus providing a rapid method for the detection of deficiencies in NAG activity. We also show that the assay is sensitive to changes in NAG activity due to increases in NAGLU expression achieved by either overexpressing the transcription factor EB (TFEB), a master regulator of lysosomal function, or by inducing TFEB activation chemically. Because of its small format, rapidity, sensitivity and reproducibility, the NAG one-step cell assay is suitable for multiple procedures, including the high-throughput screening of chemical libraries to identify modulators of NAG expression, folding and activity, and the investigation of candidate molecules and constructs for applications in enzyme replacement therapy, gene therapy, and combination therapies.

Up to five years experience with 11 mucopolysaccharidosis type VI patients

Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI, MPS VI) is a rare progressive metabolic disorder characterized by coarse facial features, hepatosplenomegaly, restrictive pulmonary function, cardiac abnormalities and stiff joints. The disease is caused by a deficiency of the lysosomal enzyme N-acetyl galactosamine 4-sulfatase which leads to glycosaminoglycan (GAG) storage in various tissues. It presents as a clinical spectrum with varying disease progressions and severities. While the phases I/II/III studies proved the effectiveness of enzyme-replacement therapy (ERT) with recombinant human arylsulfatase B, long-term data are still scarce. Over treatment periods ranging from 1.3 to 5.4 years, this prospective open-label follow-up study in 11 Dutch mucopolysaccharidosis type VI patients (age 2-18 years) showed that ERT had significant positive effects on cardiac-wall diameters (IVSd and LVMI), left and right shoulder flexions (p<0.001), liver size and spleen size (p<0.001), urinary GAG excretion (p<0.001), and the scales of quality of life (motor functioning and body functioning). ERT did not affect cardiac valve regurgitation or hearing function; HRQoL decreased slightly in two domains ('anxiety' and 'negative emotions'), and patients with the rapid and slow progressive forms of the disease differed with regard to baseline GAG excretion and GAG decrease during treatment. In conclusion, ERT had an effect on several clinical parameters. This effect was established in an open cohort of young mucopolysaccharidosis type VI patients.

Enzyme replacement therapy started at birth improves outcome in difficult-to-treat organs in mucopolysaccharidosis I mice

Since we previously observed that in patients with mucopolysaccharidosis (MPS) the storage of undegraded glycosaminoglycans (GAG) occurs from birth, in the present study we aimed to compare normal, untreated MPS I mice (knockout for alpha-l-iduronidase-IDUA), and MPS I mice treated with enzyme replacement therapy (ERT, Laronidase, 1.2mg/kg every 2 weeks) started from birth (ERT-neo) or from 2 months of age (ERT-ad). All mice were sacrificed at 6 months. Both treatments were equally effective in normalizing GAG levels in the viscera but had no detectable effect on the joint. Heart function was also improved with both treatments. On the other hand, mice treated from birth presented better outcomes in the difficult-to-treat aortas and heart valves. Surprisingly, both groups had improvements in behavior tests, and normalization of GAG levels in the brain and IDUA injection resulted in detectable levels of enzyme in the brain tissue 1h after administration. ERT-ad mice developed significantly more anti-IDUA-IgG antibodies, and mice that didn't develop antibodies had better performances in behavior tests, indicating that development of antibodies may reduce enzyme bioavailability. Our results suggest that ERT started from birth leads to better outcomes in the aorta and heart valves, as well as a reduction in antibody levels. Some poor vascularized organs, such as the joints, had partial or no benefit and ancillary therapies might be needed for patients. The results presented here support the idea that ERT started from birth leads to better treatment outcomes and should be considered whenever possible, a observation that gains relevance as newborn screening programs are being considered for MPS and other treatable lysosomal storage disorders.

Retroviral-vector-mediated gene therapy to mucopolysaccharidosis I mice improves sensorimotor impairments and other behavioral deficits

Mucopolysaccharidosis I (MPS I) is a lysosomal storage disease due to α-L-iduronidase (IDUA) deficiency that results in the accumulation of glycosaminoglycans (GAG). Systemic gene therapy to MPS I mice can reduce lysosomal storage in the brain, but few data are available regarding the effect upon behavioral function. We investigated the effect of gene therapy with a long-terminal-repeat (LTR)-intact retroviral vector or a self-inactivating (SIN) vector on behavioral function in MPS I mice. The LTR vector was injected intravenously to 6-week-old MPS I mice, and the SIN vector was given to neonatal or 6-week-old mice. Adult-LTR, neonatal-SIN, and adult-SIN-treated mice achieved serum IDUA activity of 235 ± 20 (84-fold normal), 127 ± 10, and 71 ± 7 U/ml, respectively. All groups had reduction in histochemical evidence of lysosomal storage in the brain, with the adult-LTR group showing the best response, while adult-LTR mice had reductions in lysosomal storage in the cristae of the vestibular system. Behavioral evaluation was performed at 8 months. Untreated MPS I mice had a markedly reduced ability to hold onto an inverted screen or climb down a pole. LTR-vector-treated mice had marked improvements on both of these tests, whereas neonatal-SIN mice showed improvement in the pole test. We conclude that both vectors can reduce brain disease in MPS I mice, with the LTR vector achieving higher serum IDUA levels and better correction. Vestibular abnormalities may contribute to mobility problems in patients with MPS I, and gene therapy may reduce symptoms.

Low-scale expression and purification of an active putative iduronate 2-sulfate sulfatase-Like enzyme from Escherichia coli K12

The sulfatase family involves a group of enzymes with a large degree of similarity. Until now, sixteen human sulfatases have been identified, most of them found in lysosomes. Human deficiency of sulfatases generates various genetic disorders characterized by abnormal accumulation of sulfated intermediate compounds. Mucopolysaccharidosis type II is characterized by the deficiency of iduronate 2-sulfate sulfatase (IDS), causing the lysosomal accumulation of heparan and dermatan sulfates. Currently, there are several cases of genetic diseases treated with enzyme replacement therapy, which have generated a great interest in the development of systems for recombinant protein expression. In this work we expressed the human recombinant IDS-Like enzyme (hrIDS-Like) in Escherichia coli DH5α. The enzyme concentration revealed by ELISA varied from 78.13 to 94.35 ng/ml and the specific activity varied from 34.20 to 25.97 nmol/h/mg. Western blotting done after affinity chromatography purification showed a single band of approximately 40 kDa, which was recognized by an IgY polyclonal antibody that was developed against the specific peptide of the native protein. Our 100 ml-shake-flask assays allowed us to improve the enzyme activity seven fold, compared to the E. coli JM109/pUC13-hrIDS-Like system. Additionally, the results obtained in the present study were equal to those obtained with the Pichia pastoris GS1115/pPIC-9-hrIDS-Like system (3 L bioreactor scale). The system used in this work (E. coli DH5α/pGEX-3X-hrIDS-Like) emerges as a strategy for improving protein expression and purification, aimed at recombinant protein chemical characterization, future laboratory assays for enzyme replacement therapy, and as new evidence of active putative sulfatase production in E. coli.

Outcomes of transplantation using various hematopoietic cell sources in children with Hurler syndrome after myeloablative conditioning

We report transplantation outcomes of 258 children with Hurler syndrome (HS) after a myeloablative conditioning regimen from 1995 to 2007. Median age at transplant was 16.7 months and median follow-up was 57 months. The cumulative incidence of neutrophil recovery at day 60 was 91%, acute graft-versus-host disease (GVHD) (grade II-IV) at day 100 was 25%, and chronic GVHD and 5 years was 16%. Overall survival and event-free survival (EFS) at 5 years were 74% and 63%, respectively. EFS after HLA-matched sibling donor (MSD) and 6/6 matched unrelated cord blood (CB) donor were similar at 81%, 66% after 10/10 HLA-matched unrelated donor (UD), and 68% after 5/6 matched CB donor. EFS was lower after transplantation in 4/6 matched unrelated CB (UCB) (57%; P = .031) and HLA-mismatched UD (41%; P = .007). Full-donor chimerism (P = .039) and normal enzyme levels (P = .007) were higher after CB transplantation (92% and 98%, respectively) compared with the other grafts sources (69% and 59%, respectively). In conclusion, results of allogeneic transplantation for HS are encouraging, with similar EFS rates after MSD, 6/6 matched UCB, 5/6 UCB, and 10/10 matched UD. The use of mismatched UD and 4/6 matched UCB was associated with lower EFS.

Cardiac disease in children and young adults with various lysosomal storage diseases: Comparison of echocardiographic and ECG changes among clinical groups

BACKGROUND

Lysosomal storage disease (LSD) is a rare inherited disease group. Consecutively there are few data on cardiac changes in mucopolysaccharidosis (MPS), Anderson Fabry disease (AFD), and other LSD (oLSD) including Pompe disease (PD) and Danon disease (DD), I-cell disease ICD and mucolipidosis III (ML III).

METHODS

Between 1994 and 2011, we identified 39 patients with LSD: 25 with MPS, 8 with AFD, and 6 with oLSD including PD (1), ML III (2), DD (1), and ICD (2) at our institution fulfilling the inclusion criteria of at least one echocardiogram and ECG.

RESULTS

Median age was 11.4 years (range: 2-27), 22 were females (56%). Normal echocardiograms were present in 12 patients (31%): 4 with MPS (16%), 7 AFD (88%), and 1 oLSD (17%). Valvular heart disease was present in 23 patients (59%) occurring more often in MPS (76%) and oLSD (67%) than in AFD (0%) (p < 0.001). The most common ECG abnormality was a short PR interval in 10 of 35 patients (29%) occurring in all LSD groups. Median follow-up was 5.8 (0.2-22.2) years showing diminished 5-year survival compared to an age-matched group. However, no patient died due to a cardiac cause and no cardiovascular intervention was necessary.

CONCLUSION

Echocardiographically detectable cardiovascular involvement in children with LSD is mostly confined to MPS and oLSD. Valve thickening in echo and a short PR interval in the ECG are the most frequent abnormalities. Routine repeat assessment is recommended in LSD. However, significant cardiac disease necessitating cardiac intervention is rare during a short follow-up.

Mucopolysaccharidosis: cardiologic features and effects of enzyme-replacement therapy in 24 children with MPS I, II and VI

We determined the cardiologic features of children with MPS I, II and VI, and evaluated the effect of enzyme-replacement therapy (ERT) on cardiac disease. Twenty-four children aged 1-18 years with MPS I, II or VI were prospectively evaluated with echocardiogram and electrocardiogram from the start of enzyme-replacement therapy up to 6 years of treatment. At start of therapy, 66% had abnormal cardiac geometric features. Left-ventricular mass index (LVMI) was increased in half of the patients, due mainly to concentric hypertrophy in MPS I and II and to eccentric hypertrophy in MPS VI. Regurgitation was most severe in a subgroup of young MPS VI patients (<5 years) at the mitral valve. At baseline, all patients had abnormal valves. The ECG showed no clear rhythm or conduction abnormalities; neither, in most patients, did it reflect the hypertrophy. After ERT, the LVMI Z-score normalized in 70% of the patients who had a Z-score > 2. LVMI Z-scores decreased significantly in patients with MPS I and MPS II (p = 0.04 and p = 0.032). Despite ERT, valve regurgitation increased in 60% of the patients. We conclude that all our MPS patients have cardiac abnormalities. The most severe cardiac disease was observed in a subgroup of young MPS VI patients. While ERT had an effect on LVMI and IVSd, it apparently had little or none on valve regurgitation.

Plasma and urinary levels of dermatan sulfate and heparan sulfate derived disaccharides after long-term enzyme replacement therapy (ERT) in MPS I: correlation with the timing of ERT and with total urinary excretion of glycosaminoglycans

INTRODUCTION

Mucopolysaccharidosis type I (MPS I) results in a defective breakdown of the glycosaminoglycans (GAGs) heparan sulfate and dermatan sulfate, which leads to a progressive disease. Enzyme replacement therapy (ERT) results in clearance of these GAGs from a range of tissues and can significantly ameliorate several symptoms. The biochemical efficacy of ERT is generally assessed by the determination of the total urinary excretion of GAGs. However, this has limitations. We studied the concentrations of heparan sulfate and dermatan sulfate derived disaccharides (HS and DS, respectively) in the plasma and urine of seven patients and compared these levels with total urinary GAGs (uGAGs) levels.

METHODS

Plasma and urine samples were collected at different time points relative to the weekly ERT for three non-consecutive weeks in seven MPS I patients who had been treated with ERT for at least 2.5 years. Heparan and dermatan sulfate in plasma and urine were enzymatically digested into disaccharides, and HS and DS levels were determined by HPLC-MS/MS analysis. uGAGs were measured by the DMB test.

RESULTS

The levels of HS and DS were markedly decreased compared with the levels before the initiation of ERT. However, the concentrations of DS in plasma and of both HS and DS in urine remained significantly elevated in all studied patients, while in six patients the level of total uGAGs had normalized. The concentrations of plasma and urinary HS during the weekly ERT followed a U-shaped curve. However, the effect size is small. The concentrations of plasma and urinary DS and uGAGs appeared to be in a steady state.

CONCLUSIONS

HS and DS are sensitive biomarkers for monitoring the biochemical treatment efficacy of ERT and remain elevated despite long-term treatment. This finding may be related to the labeled dose or antibody status of the patient. The timing of the sample collection is not relevant, at least at the current dose of 100 IU/kg/weekly.

Enzyme replacement therapy for Mucopolysaccharidosis Type I among patients followed within the MPS Brazil Network

Mucopolysaccharidosis type I (MPS I) is a rare lysosomal disorder caused by deficiency of alpha-L-iduronidase. Few clinical trials have assessed the effect of enzyme replacement therapy (ERT) for this condition. We conducted an exploratory, open-label, non-randomized, multicenter cohort study of patients with MPS I. Data were collected from questionnaires completed by attending physicians at the time of diagnosis (T1; n = 34) and at a median time of 2.5 years later (T2; n = 24/34). The 24 patients for whom data were available at T2 were allocated into groups: A, no ERT (9 patients; median age at T1 = 36 months; 6 with severe phenotype); B, on ERT (15 patients; median age at T1 = 33 months; 4 with severe phenotype). For all variables in which there was no between-group difference at baseline, a delta of ≥ ± 20% was considered clinically relevant. The following clinically relevant differences were identified in group B in T2: lower rates of mortality and reported hospitalization for respiratory infection; lower frequency of hepatosplenomegaly; increased reported rates of obstructive sleep apnea syndrome and hearing loss; and stabilization of gibbus deformity. These changes could be due to the effect of ERT or of other therapies which have also been found more frequently in group B. Our findings suggest MPS I patients on ERT also receive a better overall care. ERT may have a positive effect on respiratory morbidity and overall mortality in patients with MPS I. Additional studies focusing on these outcomes and on other therapies should be performed.

Current and emerging management options for patients with Morquio A syndrome

Morquio A syndrome is a lysosomal storage disease associated with mucopolysaccharidosis. It is caused by a deficiency of the lysosomal enzyme, N-acetylgalactosamine-6-sulfate sulfatase, which leads to accumulation of keratan sulfate and condroitin-6 sulfate in multiple organs. Patients present with multisystemic complications involving the musculoskeletal, respiratory, cardiovascular, and digestive systems. Presently, there is no definitive cure, and current management options are palliative. Enzyme replacement therapy and hematopoietic stem cell therapy have been proven effective in certain lysosomal storage diseases, and current investigations are underway to evaluate the effectiveness of these therapies and others for the treatment of Morquio A syndrome. This review discusses the current and emerging treatment options for Morquio A syndrome, citing examples of the treatment of other mucopolysaccharidoses.

Enzyme replacement therapy for lysosomal diseases: lessons from 20 years of experience and remaining challenges

In 1964, Christian de Duve first suggested that enzyme replacement might prove therapeutic for lysosomal storage diseases (LSDs). Early efforts identified the major obstacles, including the inability to produce large quantities of the normal enzymes, the lack of animal models for proof-of-concept studies, and the potentially harmful immune responses to the "foreign" normal enzymes. Subsequently, the identification of receptor-mediated targeting of lysosomal enzymes, the cloning and overexpression of human lysosomal genes, and the generation of murine models markedly facilitated the development of enzyme replacement therapy (ERT). However, ERT did not become a reality until the early 1990s, when its safety and effectiveness were demonstrated for the treatment of type 1 Gaucher disease. Today, ERT is approved for six LSDs, and clinical trials with recombinant human enzymes are ongoing in several others. Here, we review the lessons learned from 20 years of experience, with an emphasis on the general principles for effective ERT and the remaining challenges.

Current and emerging treatments and surgical interventions for Morquio A syndrome: a review

Patients with mucopolysaccharidosis type IVA (MPS IVA; Morquio A syndrome) have accumulation of the glycosaminoglycans, keratan sulfate, and chondroitin-6-sulfate, in bone and cartilage, causing systemic spondyloepiphyseal dysplasia. Features include lumbar gibbus, pectus carinatum, faring of the rib cage, marked short stature, cervical instability and stenosis, kyphoscoliosis, genu valgum, and laxity of joints. Generally, MPS IVA patients are wheelchair-bound as teenagers and do not survive beyond the second or third decade of life as a result of severe bone dysplasia, causing restrictive lung disease and airway narrowing, increasing potential for pneumonia and apnea; stenosis and instability of the upper cervical region; high risk during anesthesia administration due to narrowed airway as well as thoracoabdominal dysfunction; and surgical complications. Patients often need multiple surgical procedures, including cervical decompression and fusion, hip reconstruction and replacement, and femoral or tibial osteotomy, throughout their lifetime. Current measures to intervene in disease progression are largely palliative, and improved therapies are urgently needed. A clinical trial for enzyme replacement therapy (ERT) and an investigational trial for hematopoietic stem cell transplantation (HSCT) are underway. Whether sufficient enzyme will be delivered effectively to bone, especially cartilage (avascular region) to prevent the devastating skeletal dysplasias remains unclear. This review provides an overview of historical aspects of studies on MPS IVA, including clinical manifestations and pathogenesis of MPS IVA, orthopedic surgical interventions, and anesthetic care. It also describes perspectives on potential ERT, HSCT, and gene therapy.

Enzyme replacement therapy in an attenuated case of mucopolysaccharidosis type I (Scheie syndrome): a 6.5-year detailed follow-up

We present the 6.5-year follow-up of a boy with Scheie syndrome whose therapy was initiated at age 2.5 years. Detailed anthropometric features, echocardiography, ophthalmologic and audiologic examinations, psychologic tests, joint range of motion, skeletal radiographs, ultrasound studies of liver and spleen volumes, urinary glycosaminoglycans, and antibodies were documented. After 6.5 years of enzyme replacement therapy, the patient experienced a decline in overall status, and the disease progressed significantly despite treatment. The patient's height at age 9 was equal to that at age 6. The patient developed heart insufficiency and a deterioration of airway flow. The patient's intelligence quotient remained unchanged, i.e., at the average level of 86 on the Terman-Merill Scale. Magnetic resonance imaging revealed cervical spinal canal stenosis and marked spinal cord compression with myelopathy. A worsening of carpal tunnel syndrome was also evident. Ophthalmologic evaluation revealed increased central corneal thickness and intraocular pressure. In audiologic assessment, the patient's results were similar to those after 3 years of treatment. The only benefit involved temporarily improved passive and active shoulder flexion. Overall, the benefit of enzyme replacement therapy with laronidase on Scheie syndrome appeared minimal.

Experiences of parents and patients with the timing of Mucopolysaccharidosis type I (MPS I) diagnoses and its relevance to the ethical debate on newborn screening

INTRODUCTION

Newborn screening (NBS) techniques have been developed for several lysosomal storage disorders (LSDs), including Mucopolysaccharidosis type I (MPS I). MPS I is an LSD with a wide phenotypic spectrum that ranges from the severe Hurler phenotype to the attenuated Scheie phenotype. To improve the ethical discussion about NBS for MPS I, we performed an interview study to explore the experiences of MPS I patients and their parents with the timings of their diagnoses.

METHODS

We used a qualitative research approach consisting of 17 interviews with the parents of patients with all MPS I phenotypes and with patients with attenuated forms of MPS I. The interviews were audio-recorded, transcribed and subsequently analyzed to identify the main themes identified by the participants.

RESULTS

Five important themes, focusing on the experienced disadvantages of delayed diagnosis and the advantages and disadvantages of a hypothetical earlier diagnosis, were identified in our group of participants: 1) delayed diagnosis causing parental frustration, 2) delayed diagnosis causing patient frustration, 3) early diagnosis enabling reproductive decision-making, 4) early diagnosis enabling focusing on the diagnosis, and 5) early diagnosis enabling timely initiation of treatment. There was a remarkable similarity in the experiences with timing of diagnosis between parents of patients with the severe and the attenuated forms.

CONCLUSION

This was the first study to explore the personal experiences of MPS I patients and their parents with diagnostic timing. Our study identified five important themes that are highly relevant to the ethical discussion on expanding NBS programs for MPS I.