heparitin-sulfate and Mucopolysaccharidosis-VI

To explore the correlation between glycosaminoglycan (GAG) levels and mucopolysaccharidosis (MPS) type, we have evaluated the GAG levels in blood of MPS II, III, IVA, and IVB and urine of MPS IVA, IVB, and VI by tandem mass spectrometry. Dermatan sulfate (DS), heparan sulfate (HS), keratan sulfate (KS; mono-sulfated KS, di-sulfated KS), and the ratio of di-sulfated KS in total KS were measured. Patients with untreated MPS II had higher levels of DS and HS in blood while untreated MPS III had higher levels of HS in blood than age-matched controls. Untreated MPS IVA had higher levels of KS in blood and urine than age-matched controls. The ratio of blood di-sulfated KS/total KS in untreated MPS IVA was constant and higher than that in controls for children up to 10 years of age. The ratio of urine di-sulfated KS/total KS in untreated MPS IVA was also higher than that in age-matched controls, but the ratio in untreated MPS IVB was lower than controls. ERT reduced blood DS and HS in MPS II, and urine KS in MPS IVA patients, although GAGs levels remained higher than the observed in age-matched controls. ERT did not change blood KS levels in MPS IVA. MPS VI under ERT still had an elevation of urine DS level compared to age-matched controls. There was a positive correlation between blood and urine KS in untreated MPS IVA patients but not in MPS IVA patients treated with ERT. Blood and urine KS levels were secondarily elevated in MPS II and VI, respectively. Overall, measurement of GAG levels in blood and urine is useful for diagnosis of MPS, while urine KS is not a useful biomarker for monitoring therapeutic efficacy in MPS IVA.

Topics: Adolescent; Adult; Biomarkers; Child; Child, Preschool; Dermatan Sulfate; Female; Glycosaminoglycans; Heparitin Sulfate; Humans; Keratan Sulfate; Male; Mucopolysaccharidoses; Mucopolysaccharidosis II; Mucopolysaccharidosis III; Mucopolysaccharidosis IV; Mucopolysaccharidosis VI; Tandem Mass Spectrometry; Young Adult

Mucopolysaccharidoses (MPS) are complex storage disorders that result in the accumulation of glycosaminoglycans (GAGs) in urine, blood, brain and other tissues. Symptomatic patients are typically screened for MPS by analysis of GAG in urine. Current screening methods used in clinical laboratories are based on colorimetric assays that lack the sensitivity and specificity to reliably detect mild GAG elevations that occur in some patients with MPS. We have developed a straightforward, reliable method to quantify chondroitin sulfate (CS), dermatan sulfate (DS) and heparan sulfate (HS) in urine by stable isotope dilution tandem mass spectrometry. The GAGs were methanolyzed to uronic acid-N-acetylhexosamine or iduronic acid-N-glucosamine dimers and mixed with stable isotope labeled internal standards derived from deuteriomethanolysis of GAG standards. Specific dimers derived from HS, DS and CS were separated by ultra-performance liquid chromatography and analyzed by electrospray ionization tandem mass spectrometry using selected reaction monitoring for each targeted GAG product and its corresponding internal standard. The method was robust with a mean inaccuracy from 1 to 15%, imprecision below 11%, and a lower limit of quantification of 0.4mg/L for CS, DS and HS. We demonstrate that the method has the required sensitivity and specificity to discriminate patients with MPS III, MPS IVA and MPS VI from those with MPS I or MPS II and can detect mildly elevated GAG species relative to age-specific reference intervals. This assay may also be used for the monitoring of patients following therapeutic intervention. Patients with MPS IVB are, however, not detectable by this method.

Topics: Adolescent; Adult; Aged; Child; Child, Preschool; Chondroitin Sulfates; Chromatography, Liquid; Dermatan Sulfate; Glycosaminoglycans; Heparitin Sulfate; Humans; Infant; Middle Aged; Mucopolysaccharidoses; Mucopolysaccharidosis II; Mucopolysaccharidosis III; Mucopolysaccharidosis IV; Mucopolysaccharidosis VI; Radioisotope Dilution Technique; Reference Values; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry; Young Adult

Mucopolysaccharidoses (MPSs) are complex storage disorders caused by specific lysosomal enzyme deficiencies, resulting in the accumulation of glycosaminoglycans (GAGs) in urine, plasma, as well as in various tissues. We devised and validated a straightforward, but accurate and precise tandem mass spectrometry methodology coupled to high performance liquid chromatography (LC-MS/MS) for the quantification of GAGs in urine. The method is applicable to the investigation of patients with MPS I, II, and VI, by quantifying dermatan sulfate (DS) and heparan sulfate (HS) in urine. We analyzed urine samples from 28 MPS patients, aged 1 to 42 years, and 55 control subjects (41 days to 18 years old). Levels of DS and HS in urine from healthy controls of all ages were below the limit of quantification. The levels of DS and HS in urine from 6 treated patients with MPS I were lower than in 6 untreated patients in DS (0.7-45 vs 9.3-177 mg/mmol creat) and HS (0-123 mg/mmol creatinine vs 38-418 mg/mmol creatinine); similar results were obtained for 9 patients with MPS II and 7 patients with MPS VI. Analyses were performed on as little as 250 μL of urine. Methanolysis took 75 min per sample; the total analysis run time for each LC-MS/MS injection was 8 min. Results indicate that the method is applicable to a wide variety of situations in which high accuracy and precision are required, including the evaluation of the effectiveness of existing and emerging treatments.

Topics: Adolescent; Adult; Biomarkers; Case-Control Studies; Child; Child, Preschool; Chromatography, Liquid; Creatinine; Dermatan Sulfate; Enzyme Replacement Therapy; Female; Glycosaminoglycans; Heparitin Sulfate; Humans; Infant; Male; Mucopolysaccharidosis I; Mucopolysaccharidosis II; Mucopolysaccharidosis VI; Reference Values; Tandem Mass Spectrometry; Young Adult

The sulfatase enzymes, N-acetylgalactosamine-4-sulfatase (arylsulfatase B (ASB)) and galactose-6-sulfatase (GALNS) hydrolyze sulfate groups of CS. Deficiencies of ASB and GALNS are associated with the mucopolysaccharidoses. To determine if expression of ASB and GALNS impacts on glycosaminoglycans (GAGs) and proteoglycans beyond their association with the mucopolysaccharidoses, we modified the expression of ASB and GALNS by overexpression and by silencing with small interference RNA in MCF-7 cells. Content of total sulfated GAG (sGAG), chondroitin 4-sulfate (C4S), and total chondroitin sulfates (CSs) was measured following immunoprecipitation with C4S and CS antibodies and treatment with chondroitinase ABC. Following silencing of ASB or GALNS, total sGAG, C4S, and CS increased significantly. Following overexpression of ASB or GALNS, total sGAG, C4S, and CS declined significantly. Measurements following chondroitinase ABC treatment of the cell lysates demonstrated no change in the content of the other sGAG, including heparin, heparan sulfate, dermatan sulfate, and keratan sulfate. Following overexpression of ASB and immunoprecipitation with C4S antibody, virtually no sGAG was detectable. Total sGAG content increased to 23.39 (+/-1.06) microg/mg of protein from baseline of 12.47 (+/-0.68) microg/mg of protein following ASB silencing. mRNA expression of core proteins of the CS-containing proteoglycans, syndecan-1 and decorin, was significantly up-regulated following overexpression of ASB and GALNS. Soluble syndecan-1 protein increased following increases in ASB and GALNS and reduced following silencing, inversely to changes in CS. These findings demonstrate that modification of expression of the lysosomal sulfatases ASB and GALNS regulates the content of CSs.

Topics: Antibodies; Cell Line, Tumor; Chondroitin ABC Lyase; Chondroitin Sulfates; Chondroitinsulfatases; Decorin; Dermatan Sulfate; Extracellular Matrix Proteins; Female; Gene Expression Regulation, Enzymologic; Gene Silencing; Heparin; Heparitin Sulfate; Humans; Mucopolysaccharidosis VI; N-Acetylgalactosamine-4-Sulfatase; Proteoglycans; RNA, Small Interfering; Syndecan-1

N-Acetylglucosamine 6-sulfate (GlcNAc6S) has been isolated from human urine and shown to be present at levels of approximately 0.02 and 14 mg/mmole creatinine in urine from normal individuals and a mucopolysaccharidosis type IIID (MPS IIID) patient respectively. We propose that the greater than 500-fold elevation of GlcNAc6S in urine from the MPS IIID patient indicates that this sulfated monosaccharide is also a substrate for the sulfatase deficient in MPS IIID patients. We further propose that part, if not all, of the GlcNAc6S found in urine may be produced from the cleavage by beta-N-acetylhexosaminidase A of non-reducing end beta-linked GlcNAc6S residues of keratan sulfate and/or sulfated glycoproteins.

Topics: Acetylglucosamine; Chromatography; Galactosamine; Glucosamine; Heparitin Sulfate; Humans; Keratan Sulfate; Mucopolysaccharidoses; Mucopolysaccharidosis III; Mucopolysaccharidosis VI