Usefulness of urinary glycosaminoglycans assay for a mucopolysaccharidosis-specific screening

Sphingolipidoses in Morocco: Chemical profiling for an affordable and rapid diagnosis strategy

Sphingolipidoses are a group of metabolic diseases in which lysosomal hydrolases dysfunction disrupt normal sphingolipids' metabolism, leading to excess accumulation in cellular compartments and excretion in urine. These pathologies represent a significant burden among Moroccan population, for which an easy access to enzymatic assays and genetic tests is not guaranteed. Parallel analytical methods thus have to be developed for preliminary screening. In this study, 107 patients were addressed to the metabolic platform of the Marrakesh Faculty of Medicine for diagnosis confirmation. Thin-Layer Chromatography was used as a first step to perform chemical profiling of the patients' urinary lipids, allowing 36% of the patients to be efficiently oriented towards the adequate enzymatic assay. UPLC-MS/MS analyses of urinary sulfatides excreted in urines patient had been used to control the reliability of TLC analysis and to obtain more accurate information related to the sulfatides isoforms. This analytical process combining TLC with UPLC-MS/MS has enabled rapid and appropriate patient management in a reduced time and with reduced resources.

Urinary Glycosaminoglycans: Characterization and Quantification

The growing body of evidence supports the potential of using urinary glycosaminoglycans (uGAGs) levels as biomarkers to guide diagnosis and as predictive biomarkers of treatment efficacy. Recently, studies have shown that, in addition to MPS, the prognosis and treatment of cancers and viral infections, including COVID-19, are enabled by characterization and/or traits by GAGs. Reliable and accessible detection and assay protocols of urinary GAGs are therefore of great support for laboratory workers and clinicians. Here we describe a semiquantitative and quantitative urinary glycosaminoglycans determination using 1,9-dimethylmethylene blue (DMB) and the characterization of uGAGs using thin layer chromatography (TLC).

Flaxseed extract reduces tissue accumulation and enhances urinary excretion of chondroitin sulphate in the rat: a possible new path in substrate reduction therapy for mucopolysaccharidosis

CONTEXT

Chondroitin 6 sulphate (C6S) is a glycosaminoglycan (GAG) whose accumulation is notable in mucopolysaccharidosis type IVA and VII. Flaxseed, Linum usitatissimum L. (Linaceae) (FS), is reported to have comparable properties to those of soybean, a source of genistein, a potential new treatment for MPSs.

OBJECTIVE

We assess the effect of total ethanol flaxseed extract (EFSE) in an animal model of C6S accumulation.

MATERIALS AND METHODS

The study was performed in adult male Wistar rats (n = 24) for 15 successive days. The animals were divided into four groups: (1) control injected with physiological saline buffer, (2) intoxicated rats injected intraperitoneally with C6S, (3) intoxicated with C6S and treated with EFSE, and (4) treated with EFSE. All groups were subjected to histopathological and biochemical studies. The antioxidant and phytochemical properties of EFSE were examined.

RESULTS

Dry EFSE contains total phenols (6.28 mg EAG/g), condensed tannins (2.98 mg ECAT/g) and flavonoids (0.44 mg ECAT/g) with high antioxidant potential [RPE (IC₅₀ = 8.37 ± 0.176), DPPH (IC₅₀ = 12.79 ± 0.273)]. The LD₅₀ is higher than 5000 mg/kg. The histopathological examination showed an accumulation of C6S in the C6S intoxicated group, which disappeared in the C6S-EFSE treated group. GAGs assays showed an increased excretion in the C6S intoxicated group and increased excretion of 14% in the C6S-EFSE group compared to the C6S group.

DISCUSSION AND CONCLUSIONS

EFSE showed significant potential for chelation. Its use for the treatment of GAG accumulation could be suggested and generalized to a larger study population.

The Endothelial Glycocalyx: Physiology and Pathology in Neonates, Infants and Children

The endothelial glycocalyx (EG) as part of the endothelial surface layer (ESL) is an important regulator of vascular function and homeostasis, including permeability, vascular tone, leukocyte recruitment and coagulation. Located at the interface between the endothelium and the blood stream, this highly fragile structure is prone to many disruptive factors such as inflammation and oxidative stress. Shedding of the EG has been described in various acute and chronic diseases characterized by endothelial dysfunction and angiopathy, such as sepsis, trauma, diabetes and cardiovascular disease. Circulating EG components including syndecan-1, hyaluronan and heparan sulfate are being evaluated in animal and clinical studies as diagnostic and prognostic markers in several pathologies, and advances in microscopic techniques have enabled in vivo assessment of the EG. While research regarding the EG in adult physiology and pathology has greatly advanced throughout the last decades, our knowledge of the development of the glycocalyx and its involvement in pathological conditions in the pediatric population is limited. Current evidence suggests that the EG is present early during fetal development and plays a critical role in vessel formation and maturation. Like in adults, EG shedding has been demonstrated in acute inflammatory conditions in infants and children and chronic diseases with childhood-onset. However, the underlying mechanisms and their contribution to disease manifestation and progression still need to be established. In the future, the glycocalyx might serve as a marker to identify pediatric patients at risk for vascular sequelae and as a potential target for early interventions.

Deep intronic variant in the ARSB gene as the genetic cause for Maroteaux-Lamy syndrome (MPS VI)

Maroteaux-Lamy syndrome (MPS-VI) is a rare autosomal-recessive disorder with a wide spectrum of clinical manifestations, ranging from an attenuated to a rapidly progressive disease. It is caused by variants in ARSB, which encodes the lysosomal arylsulfatase B (ARSB) enzyme, part of the degradation process of glycosaminoglycans in lysosomes. Over 220 variants have been reported so far, with a majority of missense variants. We hereby report two siblings of Bedouin origin with a diagnosis of MPS-VI. Western blots in patient fibroblasts revealed total absence of ARSB protein production. Complete sequencing of the coding region of ARSB did not identify a candidate disease-associated variant. However, deep sequencing of the noncoding region of ARSB by whole genome sequencing (WGS) revealed a c.1142+581A to G variant. The variant is located within intron 5 and fully segregated with the disease in the family. Determination of the genetic cause for these patients enabled targeted treatment by enzyme replacement therapy, along with appropriate genetic counseling and prenatal diagnosis for the family. These results highlight the advantage of WGS as a powerful tool, for improving the diagnostic rate of rare disease-causing variants, and emphasize the importance of studying deep intronic sequence variation as a cause of monogenic disorders.

Is hematopoietic stem cell transplantation a therapeutic option for mucolipidosis type II?

BACKGROUND

Mucolipidosis type II (MLII) is an ultra-rare lysosomal storage disorder caused by defective lysosomal enzyme trafficking. Clinical hallmarks are craniofacial dysmorphia, cardiorespiratory dysfunction, hepatosplenomegaly, skeletal deformities and neurocognitive retardation. Death usually occurs in the first decade of life and no cure exists. Hematopoietic stem cell transplantation (HSCT) has been performed in few MLII patients, but comprehensive follow-up data are extremely scarce.

METHODS

MLII diagnosis was confirmed in a female three-month-old patient with the mutations c.2213C > A and c.2220_2221dup in the GNPTAB gene. At nine months of age, the patient received HSCT from a 9/10 human leukocyte antigen (HLA)-matched unrelated donor.

RESULTS

HSCT resulted in a sustained reduction of lysosomal storage und bone metabolism markers. At six years of age, the patient showed normal cardiac function, partial respiratory insufficiency and moderate hepatomegaly, whereas skeletal manifestations had progressed. However, the patient could walk and maintained an overall good quality of life. Neurocognitive testing revealed a developmental quotient of 36%. The patient died at 6.6 years of age following a human metapneumovirus (hMPV) pneumonia.

CONCLUSIONS

The exact benefit remains unclear as current literature vastly lacks comparable data on MLII natural history patients. In order to evaluate experimental therapies, in-depth prospective studies and registries of untreated MLII patients are indispensable.