Long circulating enzyme replacement therapy rescues bone pathology in mucopolysaccharidosis VII murine model.

Mucopolysaccharidosis (MPS) type VII is a lysosomal storage disease caused by deficiency of the lysosomal enzyme ß-glucuronidase (GUS), leading to accumulation of glycosaminoglycans (GAGs). Enzyme replacement therapy (ERT) effectively clears GAG storage in the viscera. Recent studies showed that a chemically modified form of GUS (PerT-GUS), which escaped clearance by mannose 6-phosphate and mannose receptors and showed prolonged circulation, reduced CNS storage more effectively than native GUS. Clearance of storage in bone has been limited due to the avascularity of the growth plate. To evaluate the effectiveness of long-circulating PerT-GUS in reducing the skeletal pathology, we treated MPS VII mice for 12 weeks beginning at 5 weeks of age with PerT-GUS or native GUS and used micro-CT, radiographs, and quantitative histopathological analysis for assessment of bones. Micro-CT findings showed PerT-GUS treated mice had a significantly lower BMD. Histopathological analysis also showed reduced storage material and a more organized growth plate in PerT-GUS treated mice compared with native GUS treated mice. Long term treatment with PerT-GUS from birth up to 57 weeks also significantly improved bone lesions demonstrated by micro-CT, radiographs and quantitative histopathological assay. In conclusion, long-circulating PerT-GUS provides a significant impact to rescue of bone lesions and CNS involvement.

Oral immunotherapy tolerizes mice to enzyme replacement therapy for Morquio A syndrome.

Immune response to therapeutic enzymes poses a detriment to patient safety and treatment outcome. Enzyme replacement therapy (ERT) is a standard therapeutic option for some types of mucopolysaccharidoses, including Morquio A syndrome caused by N-acetylgalactosamine-6-sulfate sulfatase (GALNS) deficiency. Current protocols tolerize patients using cytotoxic immunosuppressives, which can cause adverse effects. Here we show development of tolerance in Morquio A mice via oral delivery of peptide or GALNS for 10 days prior to ERT. Our results show that using an immunodominant peptide (I10) or the complete GALNS enzyme to orally induce tolerance to GALNS prior to ERT resulted in several improvements to ERT in mice: (a) decreased splenocyte proliferation after in vitro GALNS stimulation, (b) modulation of the cytokine secretion profile, (c) decrease in GALNS-specific IgG or IgE in plasma, (d) decreased GAG storage in liver, and (e) fewer circulating immune complexes in plasma. This model could be extrapolated to other lysosomal storage disorders in which immune response hinders ERT.

[Computational prediction of the tertiary structure of the human iduronate 2-sulfate sulfatase]. / Predicción computacional de la estructura terciaria de la iduronato 2-sulfato sulfatasa humana.

INTRODUCTION: Hunter syndrome (MC KUSIK 309900) or mucopolysacharidosis type II is due to the deficiency of the enzyme iduronate 2 sulfate sulfatase (E.C. 3.1.6.13). This enzyme has not been crystallized, and therefore the experimental structures are not available. OBJECTIVES: A computational three-dimensional model was proposed for the iduronate 2 sulfate sulfatase enzyme. MATERIALS AND METHODS: A computational analysis of this enzyme used the following free internet software programs: Comput pI/MW, JaMBW Chapter 3.1.7, SWISS-MODEL, Geno3d, ProSup. Energy minimization was done with Discover 3 and Insight II version 2004. RESULTS: A three-dimensional conformational model was proposed. The model showed 33.3% of helix structure, 7.2% beta sheet, and 59.5% random coil. RMS values (Root Mean Square) (0.78 and 0.86A) were found when compared with other enzymes of the same family. The model presented 5 exposed N-glycosylation potential sites and an entry to the pocket that contains the amino acids of the active site. A high correlation was found between the type of mutations and the severity of the phenotype in twenty patients analyzed. CONCLUSION: The RMS values, as well as the high correlation between the type of mutation and the phenotype, indicated that the model predicts some aspects of the enzymes biological behavior.