Recent scientific articles relevant to Sanfilippo Syndrome: January – March 2023, digest

July 7, 2023

Every week thousands of scientific articles on various topics are published. Here are some recent articles and abstracts that are relevant to understanding, managing, and/or treating Sanfilippo Syndrome (mucopolysaccharidosis III or MPS III) from January 2023 to March 2023.

“N-Substituted l-Iminosugars for the Treatment of Sanfilippo Type B Syndrome”

Published: Journal of Medicinal Chemistry, February 9, 2023

Authors: Valeria De Pasquale, Anna Esposito, Gianluca Scerra, Melania Scarcella, Mariangela Ciampa, Antonietta Luongo, Daniele D’Alonzo, Annalisa Guaragna, Massimo D’Agostino, and Luigi Michele Pavone

Abstract: “Sanfilippo syndrome comprises a group of four genetic diseases due to the lack or decreased activity of enzymes involved in heparan sulfate (HS) catabolism. HS accumulation in lysosomes and other cellular compartments results in tissue and organ dysfunctions, leading to a wide range of clinical symptoms including severe neurodegeneration. To date, no approved treatments for Sanfilippo disease exist. Here, we report the ability of N-substituted l-iminosugars to significantly reduce substrate storage and lysosomal dysfunctions in Sanfilippo fibroblasts and in a neuronal cellular model of Sanfilippo B subtype. Particularly, we found that they increase the levels of defective α-N-acetylglucosaminidase and correct its proper sorting toward the lysosomal compartment. Furthermore, l-iminosugars reduce HS accumulation by downregulating protein levels of exostosin glycosyltransferases. These results highlight an interesting pharmacological potential of these glycomimetics in Sanfilippo syndrome, paving the way for the development of novel therapeutic approaches for the treatment of such incurable disease.”

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“Safety, pharmacokinetics and CNS distribution of tralesinidase alfa administered via intracerebroventricular infusion to juvenile cynomolgus monkeys”

Published: Toxicology Reports, March 1, 2023

Authors: Jason Pinkstaff, Emma McCullagh, Anita Grover, Andrew C Melton, Anu Cherukuri, Jill Cm Wait, Annalisa Nguyen, Mark T Butt, Jami L Trombley, Randall P Reed, Eric L Adams, Robert B Boyd, Sundeep Chandra, Joshua Henshaw, Charles A O’Neill, Eric Zanelli, Joseph Kovalchin

Abstract: “Mucopolysaccharidosis Type IIIB (MPS IIIB) is an ultrarare, fatal pediatric disease with no approved therapy. It is caused by mutations in the gene encoding for lysosomal enzyme alpha-N-acetylglucosaminidase (NAGLU). Tralesinidase alfa (TA) is a fusion protein comprised of recombinant NAGLU and a modified human insulin-like growth factor 2 that is being developed as an enzyme replacement therapy for MPS IIIB. Since MPS IIIB is a pediatric disease the safety/toxicity, pharmacokinetics and biodistribution of TA were evaluated in juvenile non-human primates that were administered up to 5 weekly intracerebroventricular (ICV) or single intravenous (IV) infusions of TA. TA administered by ICV slow-, ICV isovolumetric bolus- or IV-infusion was well-tolerated, and no effects were observed on clinical observations, electrocardiographic or ophthalmologic parameters, or respiratory rates. The drug-related changes observed were limited to increased cell infiltrates in the CSF and along the ICV catheter track after ICV administration. These findings were not associated with functional changes and are associated with the use of ICV catheters. The CSF PK profiles were consistent across all conditions tested and TA distributed widely in the CNS after ICV administration. Anti-drug antibodies were observed but did not appear to significantly affect the exposure to TA. Correlations between TA concentrations in plasma and brain regions in direct contact with the cisterna magna suggest glymphatic drainage may be responsible for clearance of TA from the CNS. The data support the administration of TA by isovolumetric bolus ICV infusion to pediatric patients with MPS IIIB.”

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“Quantification of glycosaminoglycans in urine by isotope-dilution liquid chromatography-electrospray ionization tandem mass spectrometry”

Published: Current Protocols in Human Genetics, March 16, 2023

Authors: Haoyue Zhang, Sarah P. Young, David S. Millington

Abstract: “Mucopolysaccharidoses (MPSs) are complex lysosomal storage disorders that result in the accumulation of glycosaminoglycans (GAGs) in urine, blood, and tissues. Lysosomal enzymes responsible for GAG degradation are defective in MPSs. GAGs including chondroitin sulfate (CS), dermatan sulfate (DS), heparan sulfate (HS), and keratan sulfate (KS) are disease-specific biomarkers for MPSs. This article describes a stable isotope dilution-tandem mass spectrometric method for quantifying CS, DS, and HS in urine samples. The GAGs are methanolyzed to uronic or iduronic acid-N-acetylhexosamine or iduronic acid-N-sulfo-glucosamine dimers and mixed with internal standards derived from deuteriomethanolysis of GAG standards. Specific dimers derived from HS, DS, and CS are separated by ultra-performance liquid chromatography (UPLC) and analyzed by electrospray ionization tandem mass spectrometry (MS/MS) using selected reaction monitoring for each targeted GAG product and its corresponding internal standard. This UPLC-MS/MS GAG assay is useful for identifying patients with MPS types I, II, III, VI, and VII.”

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“Histological characterization of retinal degeneration in mucopolysaccharidosis type IIIC”

Published: Experimental Eye Research, April 1, 2023

Authors: Jessica Ludwig, Onkar B Sawant, Jill Wood, Srikanth Singamsetty, Xuefang Pan, Vera L Bonilha, Sujata Rao, Alexey V Pshezhetsky

Abstract: “Heparan-α-glucosaminide N-acetyltransferase (HGSNAT) participates in lysosomal degradation of heparan sulfate. Mutations in the gene encoding this enzyme cause mucopolysaccharidosis IIIC (MPS IIIC) or Sanfilippo syndrome type C. MPS IIIC patients exhibit progressive neurodegeneration, leading to dementia and death in early adulthood. Currently there is no approved treatment for MPS IIIC. Incidences of non-syndromic retinitis pigmentosa and early signs of night blindness are reported in some MPS IIIC patients, however the majority of ocular phenotypes are not well characterized. The goal of this study was to investigate retinal degeneration phenotype in the Hgsnat knockout mouse model of MPS IIIC and a cadaveric human MPS IIIC eye. Cone and rod photoreceptors in the eyes of homozygous 6-month-old Hgsnat knockout mice and their wild-type counterparts were analyzed using cone arrestin, S-opsin, M-opsin and rhodopsin antibodies. Histological observation was performed on the eye from a 35-year-old MPS IIIC donor. We observed a nearly 50% reduction in the rod photoreceptors density in the Hgsnat knockout mice compared to the littermate wild-type controls. Cone photoreceptor density was unaltered at this age. Severe retinal degeneration was also observed in the MPS IIIC donor eye. To our knowledge, this is the first report characterizing ocular phenotypes arising from deleterious variants in the Hgsnat gene associated with MPS IIIC clinical phenotype. Our findings indicate retinal manifestations may be present even before behavioral manifestations. Thus, we speculate that ophthalmological evaluations could be used as diagnostic indicators of early disease, progression, and end-point evaluation for future MPS IIIC therapies.”

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Source: All information is sourced directly from the scientific abstracts and articles published by the researchers.

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