Composition and structure of glycosaminoglycans in DBS from 2-3-day-old newborns for the diagnosis of mucopolysaccharidosis.

Dried blood spot (DBS) technology is a cheap and easy method largely applied in newborn screening. Mucopolysaccharidoses (MPS) are characterized by the deficit of enzymes that degrade glycosaminoglycans (GAGs) characterized by progressive worsening of the conditions. For a possible early diagnosis of MPS, we developed a method of uronic acid (UA)-GAGs determination in DBS of 600 healthy newborns and from a small group of MPS subjects matched for age. Spotted blood UA-GAGs of the normal newborns are composed of 67.2% chondroitin sulfate (CS), 28.6% heparan sulfate (HS) and 4.4% hyaluronic acid with a CS/HS ratio of 2.35 and a total GAGs content of 0.43 µg/DBS. A chemical evaluation of CS and HS structure was performed by measuring their disaccharide composition, sulfation and the overall charge density. The DBS of four different MPS types presented an increase of total or single UA-GAGs content and/or modifications of the CS and HS disaccharide composition as well as chemical signature also related to the MPS enzymatic defect. The modifications of the UA-GAGs composition, parameters and structure of healthy newborns determined in DBS would be useful for a possible early diagnosis of various MPS types.

12 year follow up of enzyme-replacement therapy in two siblings with attenuated mucopolysaccharidosis I: the important role of early treatment.

BACKGROUND: Mucopolysaccharidosis type I is an autosomal recessive disorder caused by deficiency of α-L-iduronidase and characterized by a progressive course with multisystem involvement. Clinically, Mucopolysaccharidosis type I is classified into two forms: severe (Hurler syndrome), which presents in infancy and is characterized by rapid progressive neurological involvement and attenuated (Hurler/Scheie and Scheie syndromes), which presents with slower progression and absent to mild nervous system involvement. The specific treatment for attenuated Mucopolysaccharidosis type I consists of enzyme-replacement therapy with laronidase (human recombinant α-L-iduronidase, Aldurazyme). We present here the clinical and laboratory results in an 12-year-old patient affected by the attenuated form of Mucopolysaccharidosis type I treated by enzyme-replacement therapy from the age of 5 months, compared with his 17 year old affected sister, who started therapy at 5 years of age. CASE PRESENTATION: Clinical evaluation of these siblings shows that initiation of therapy prior of the onset of clinically detectable disease resulted in considerable improvement in outcome in the young sibling. After 12 years of enzyme-replacement therapy, facial appearance, linear growth rate, and liver and spleen volumes were normal; moreover, the degree of joint disease, vertebral, and cardiac valvular involvement were only minimal compared with those of his sister. CONCLUSION: This study demonstrates that early diagnosis and early initiation of enzyme-replacement therapy substantially modify the natural history of the attenuated form of Mucopolysaccharidosis type I.

Metabolic fate of milk glycosaminoglycans in breastfed and formula fed newborns.

In this study, the content, structure and residual percentages of glycosaminoglycans (GAGs) in the feces of seven breastfed newborns after ingesting a known amount of milk were studied. A comparison was made with five newborns fed with formula milk. Characterization of GAGs from milk and feces samples was performed according to previous methodology. Compared to the ingested GAGs present in milk, residual feces GAGs of breastfed newborns were <0.4 %, contrary to formula milk fed children, where the residues were ~4 %. As a consequence, >99 % of human milk GAGs are utilized as opposed to ~96 % of formula milk. Hyaluronic acid utilization was found to be fairly similar contrary to chondroitin sulfate/dermatan sulfate and heparan sulfate, which were found to be ~10-18 times lower in formula milk fed children. Our new results further demonstrate that the elevated content of human milk GAGs passes undigested through the entire digestive system of newborns, possibly protecting the infant from infections. In the distal gastrointestinal tract, these complex macromolecules are catabolized by a cohort of bacterial enzymes and constituent monosaccharides/oligosaccharides utilized for further metabolic purposes potentially useful for bacteria metabolism or internalized by intestinal cells. Thanks to their elevated structural heterogeneity, milk GAGs are used differently depending on their distinct primary structure. Finally, a different utilization and availability was observed for human milk GAGs compared to formula milk due to their various composition and structural heterogeneity.

Human milk glycosaminoglycans inhibit in vitro the adhesion of Escherichia coli and Salmonella fyris to human intestinal cells.

BACKGROUND: Breast-fed infants have a lower incidence of acute gastroenteritis due to the presence of several anti-infective factors in human milk. The aim of this work is to study the capacity of human milk glycosaminoglycans (GAGs) to inhibit the adhesion of some common pathogenic bacteria. METHODS: GAGs were isolated from a pool of milk samples collected from different mothers during the first month of lactation. Experiments were carried out to study the ability of GAGs to inhibit the adhesion of two intestinal micro-organisms (enteropathogenic Escherichia coli serotype 0119 and Salmonella fyris) to Caco-2 and Int-407 cell lines. RESULTS: The study showed that the GAGs had an anti-adhesive effect on the two pathogenic strains studied with different degrees of inhibition. In particular, in the presence of human milk GAGs, the adhesion of S. fyris to Caco-2 cells and to Int-407 cells of both tested strains was significantly reduced. CONCLUSION: Our results demonstrated that GAGs in human milk can be one of the important defensive factors against acute diarrheal infections in breast-fed infants.

Effect of holder pasteurisation on human milk glycosaminoglycans.

OBJECTIVES: The benefits of human milk for preterm infants are mainly the result of its nutritional characteristics and the presence of biologically active compounds. Among these compounds, glycosaminoglycans (GAGs) play an emerging leading role. When mother's milk is unavailable or in short supply, pasteurised donor milk represents an important nutritional alternative. The aim of this study was to evaluate the effect of Holder pasteurisation on the concentration of different GAGs in preterm human milk. METHODS: Milk samples collected from 9 mothers having delivered preterm were divided into 2 parts. One part of each sample was immediately frozen (-80°C), whereas the other part was pasteurised with the Holder method before being frozen at -80°C. Specific analytical procedures were applied to evaluate the amount, composition, and structure of main human milk GAGs. RESULTS: No significative differences were measured between not-treated and pasteurised samples for total GAGs content, relative percentages of chondroitin sulfate and heparan sulfate, and main parameters related to galactosaminoglycans structure, even if a slight decrease of total GAGs content of ∼18% was observed in treated samples. CONCLUSIONS: Our results indicate that the Holder pasteurisation does not significatively affect the concentration of the main human milk GAGs.

Capillary electrophoresis separation of human milk neutral and acidic oligosaccharides derivatized with 2-aminoacridone.

Human milk is a unique fluid in glycobiology due to the presence of many free structurally complex oligosaccharides emerging as important dietary factors during early life and having many biological and protective functions. Methods that allow accurate profiling of oligosaccharide mixtures in this complex biological fluid with quantification of the four known genetically determined groups are welcomed. A high-voltage CE separation and detection at 254 nm of 17 neutral and acidic human milk oligosaccharide (HMO) standard along with lactose derivatized with 2-aminoacridone, using a BGE containing 20% methanol as an organic modifier and borate, able to form on-capillary anionic borate-polyol complexes, is reported. This CE approach was able to separate both neutral HMOs and acidic HMOs, with the sialic acid residue, also in the presence of lactose in high content. This method was applied to the four secretory groups individually extracted by a rapid and simple preparative step. LODs were found ranging from ∼50 to 700 fmol. We were able to measure HMO content also in the presence of excess fluorophore, or interference from proteins, peptides, salts, and other impurities normally present in this complex biological fluid. Overall, CE equipped with a UV detector is a common analytical approach and this simple CE separation offers high resolution and sensitivity for the differentiation of human milk samples related to genetic groups and days of lactation by considering that important changes in HMO content are a reflection of the lactation day.

Plasmatic kinetics of dermatan sulfate during enzyme replacement therapy with iduronate-2-sulfatase in a mucopolysaccharidosis II patient.

Enzyme replacement therapy (ERT) is the worldwide standard of care for a number of mucopolysaccharidosis (MPS) diseases. We report a kinetic study of plasmatic dermatan sulfate (DS) in a 3-year-old subject affected by a severe form of MPS II during the first 10 months of ERT with Idursulfase. A strong increase in the DS plasmatic concentration was measured immediately after the first enzyme infusion, with a maximum after 3 h, followed by a continuous decrease in the 8-15 days following the beginning of treatment. After this, a constant plasmatic content of DS concentration was observed. Overall, during the 10-month treatment period, ERT reduced the plasmatic concentration of DS up to ~80-85 %, but it was unable to totally remove it from the blood. We can suppose that immediately after the first enzyme administrations, a large amount of abnormal DS is removed from tissues reaching the blood compartment and eliminated via the urine, and thereafter only minimal changes are observed. The persistency of the residual amounts of DS with the actually recommended dosage in our Patient may suggest the opportunity to promote further studies with increased enzyme dosages to completely remove the accumulation of lysosomal DS.

On-line high-performance liquid chromatography-fluorescence detection-electrospray ionization-mass spectrometry profiling of human milk oligosaccharides derivatized with 2-aminoacridone.

A high-resolution normal-phase high-performance liquid chromatography-fluorescence detection-electrospray ionization-mass spectrometry separation and structural characterization of the main oligosaccharides along with lactose from human milk samples is described. A total of 22 commercially available oligosaccharides were fluorotagged with 2-aminoacridone and separated on an amide column and identified on the basis of their retention times and mass spectra. Derivatized species having mass lower than approximately 800 to 900 exhibited mainly [M-H](-1) anions, oligomers with mass up to approximately 1000 to 1100 were represented by both [M-H](-1) and [M-2H](-2) anions, and oligomers greater than approximately 1200 to 1300 were characterized by a charge state of -3. Furthermore, the retention times were directly related to the glycans' molecular mass. Human milk samples from the four groups of donors (Se±/Le±) were analyzed for their composition and amount of free oligosaccharides after rapid and simple prepurification and derivatization steps also in the presence of lactose in high content. This analytical approach enabled us to perform the determination of species not detected by traditional techniques, such as sialic acid, as well as of species present in low content easily mistaken with other peaks. Finally, labeled human milk oligosaccharides were analyzed without any interference from excess fluorophore or interference from proteins, peptides, salts, and other impurities normally present in this complex biological fluid.

Composition and structure elucidation of human milk glycosaminoglycans.

To date, there is no complete structural characterization of human milk glycosaminoglycans (GAGs) available nor do any data exist on their composition in bovine milk. Total GAGs were determined on extracts from human and bovine milk. Samples were subjected to digestion with specific enzymes, treated with nitrous acid, and analyzed by agarose-gel electrophoresis and high-performance liquid chromatography for their structural characterization. Quantitative analyses yielded ∼7 times more GAGs in human milk than in bovine milk. In particular, galactosaminoglycans, chondroitin sulfate (CS) and dermatan sulfate (DS), were found to differ considerably from one type of milk to the other. In fact, hardly any DS was observed in human milk, but a low-sulfated CS having a very low charge density of 0.36 was found. On the contrary, bovine milk galactosaminoglycans were demonstrated to be composed of ∼66% DS and 34% CS for a total charge density of 0.94. Structural analysis performed by heparinases showed a prevalence of fast-moving heparin over heparan sulfate, accounting for ∼30-40% of total GAGs in both milk samples and showing lower sulfation in human (2.03) compared with bovine (2.28). Hyaluronic acid was found in minor amounts. This study offers the first full characterization of the GAGs in human milk, providing useful data to gain a better understanding of their physiological role, as well as of their fundamental contribution to the health of the newborn.

High-throughput determination of urinary hexosamines for diagnosis of mucopolysaccharidoses by capillary electrophoresis and high-performance liquid chromatography.

Mucopolysaccharidoses (MPS) diagnosis is often delayed and irreversible organ damage can occur, making possible therapies less effective. This highlights the importance of early and accurate diagnosis. A high-throughput procedure for the simultaneous determination of glucosamine and galactosamine produced from urinary galactosaminoglycans and glucosaminoglycans by capillary electrophoresis (CE) and HPLC has been performed and validated in subjects affected by various MPS including their mild and severe forms, Hurler and Hurler-Scheie, Hunter, Sanfilippo, Morquio, and Maroteaux-Lamy. Contrary to other analytical approaches, the present single analytical procedure, which is able to measure total abnormal amounts of urinary GAGs, high molecular mass, and related fragments, as well as specific hexosamines belonging to a group of GAGs, would be useful for possible application in their early diagnosis. After a rapid urine pretreatment, free hexosamines are generated by acidic hydrolysis, derivatized with 2-aminobenzoic acid and separated by CE/UV in ∼10min and reverse-phase (RP)-HPLC in fluorescence in ∼21min. The total content of hexosamines was found to be indicative of abnormal urinary excretion of GAGs in patients compared to the controls, and the galactosamine/glucosamine ratio was observed to be related to specific MPS syndromes in regard to both their mild and severe forms. As a consequence, important correlations between analytical response and clinical diagnosis and the severity of the disorders were observed. Furthermore, we can assume that the severity of the syndrome may be ascribed to the quantity of total GAGs, as high-molecular-mass polymers and fragments, accumulated in cells and directly excreted in the urine. Finally, due to the high-throughput nature of this approach and to the equipment commonly available in laboratories, this method is suitable for newborn screening in preventive public health programs for early detection of MPS disorders, diagnosis, and their treatment.

Oligosaccharides in 4 different milk groups, Bifidobacteria, and Ruminococcus obeum.

OBJECTIVES: The aim of this study was to identify a link between the total amount of breast milk oligosaccharides and faecal microbiota composition of newborns at the end of the first month of life, with special attention paid to bifidobacteria, and establish the role, if any, of the different oligosaccharides in determining the gut microbiota composition. SUBJECTS AND METHODS: Milk oligosaccharide groups were identified by high-performance anion exchange chromatography analysis. DPCRNA from newborns' faecal samples at 30 days of life was isolated and processed by polymerase chain reaction analyses that allow the identification of 6 species of bifidobacteria (adolescentis, bifidum, breve, catenulatum, longum, infantis) and Ruminococcus spp; denaturing gradient gel electrophoresis analysis was also performed. RESULTS: No substantial differences in bifidobacteria species composition within milk groups 1, 2, and 3 were observed; however, infants fed with group 4 milk show a microbiota characterised by a greater frequency of Bifidobacteria adolescentis and the absence of Bifidobacteria catenulatum. For the first time, a high percentage of the Ruminococcus genus in infants fed with all milk groups was found. CONCLUSIONS: Our data show that milk groups 1, 2, and 3, containing an amount of oligosaccharides ranging within 10 to 15 g/L, share a substantially identical composition of the intestinal microbiota in breast-fed infants, despite quali-quantitative difference in oligosaccharides content. Newborns taking milk with only 5 g/L of oligosaccharides (group 4) harbour a different intestinal microbiota.

Effect of 6 years of enzyme replacement therapy on plasma and urine glycosaminoglycans in attenuated MPS I patients.

Enzyme-replacement therapy (ERT) is a new option for the clinical management of MPS I. However, no detailed data are available on the structural characterization of glycosaminoglycans (GAGs) in the urine and plasma of patients before ERT and during treatment regimens. Before ERT and over a two-week period of enzyme infusion, GAGs in urine and plasma were analyzed in two patients with the Hurler-Scheie form of MPS I subjected to ERT for 6 years. In both patients before ERT, high amounts of a GAG were found in the urine, composed in particular of a high molecular mass polymer (approximately 13,000-13,500) consisting of approximately 75-78% iduronic acid and rich in 4-sulfated disaccharides (DeltaDi4s) and attributable to DS. Furthermore, a high amount of this GAG was directly detected in the blood. Plasma GAGs in MPS I patients subjected to ERT were found to be comparable to those of normal subjects with the absence of heparan sulfate and of DS. On the contrary, a polysaccharide possessing a high molecular mass, approximately 11,500-12,000, lower than the polymer extracted before ERT but slightly higher than the controls (approximately 11,000), was found in the urine of both patients. This macromolecule was characterized as a mixture of DS/chondroitin sulfate based on the high percentage of 4-sulfated disaccharide (4s/6s ratio of approximately 3.1) and iduronic acid ( approximately 60%). These results are indicative of the incapacity of ERT at the standard dose to definitively eliminate DS from the urine. Finally, a variable effect of ERT depending on each administration was also observed.

Human milk glycosaminoglycan composition from women of different countries: a pilot study.

Objective: In this pilot study, we report the composition, structure and properties of glycosaminoglycans (GAG) present in milk samples of various countries and ethnicities.Methods: Fifty samples of human milk were analyzed, 10 from east Europe, 10 from North Africa, 10 from Central Africa, 10 from South America and 10 from Asia. Moreover, 30 samples were obtained during the first week and 20 between 8 to 30 days of life.Results: Overall, no significant differences were observed for the qualitative composition of GAGs, mainly chondroitin sulfate, heparan sulfate and hyaluronic acid, comparing the mothers from the various countries and between the 30 milks obtained during the first week and the 20 samples collected thereafter. Moreover, no significant differences in human milk GAGs within the different groups analyzed belonging to various counties and ethnicities were observed.Conclusions: These results may be of useful, as in the case of pilot studies with infant formulas enriched with chondroitin sulfate (CS) and/or heparan sulfate (HS) necessary to verify their possible positive effects on newborns feeding in countries at high risk of infection and/or infestation.

Breast milk oligosaccharides: effects of 2'-fucosyllactose and 6'-sialyllactose on the adhesion of Escherichia coli and Salmonella fyris to Caco-2 cells.

Background: It is well known that human milk oligosaccharides play an important role as prebiotics, anti-inflammatory, and anti-infective agents. In the last few years, several studies have been performed using specific oligosaccharides, such as 2'-fucosyllactose and 6'-sialylactose, to evaluate their biological functions. Objectives: The aim of the present study is to evaluate the anti-adhesive effect of the above oligosaccharides on Escherichia coli and Salmonella fyris. Methods: Adhesion experiments were performed in the presence of 2'-fucosyllactose and 6'-sialyllactose as potential inhibitors of Escherichia coli and Salmonella fyris adhesion to Caco-2 cells. The oligosaccharides were used at different concentrations and the adhesion experiments were performed in triplicate and repeated at least three times. Results: A significant reduction of Escherichia coli adhesion was observed in the presence of 2'-fucosyllactose and 6'-sialyllactose at the human milk concentration. On the contrary, no positive effects were observed in both oligosaccharides on Salmonella firis. Conclusions: Our results suggest that the supplementation in infant formulas of 2'-fucosyllactose and 6'-sialyllactose, actually commercially available and absent in cow milk, could play positive effects in artificially fed infants.

False positive screen test for mucopolysaccharidoses in healthy female newborns.

BACKGROUND: In total, 930 urine samples obtained on 2nd and 3rd day from birth have been analyzed for the early diagnosis of Mucopolysaccharidoses. METHODS: Dimethylmethylene blue (DMB) assay and one-dimensional electrophoresis were performed in all urine samples. Agarose gel electrophoresis, before and after treatment with chondroitinase ABC and heparinases, was used for a comprehensive characterization. RESULTS: Out of 930 urine samples 7 showed anomalous electrophoretic pattern; 5 of them had high GAG levels by DMB test. Atypical samples (n = 7) were analyzed by agarose gel electrophoresis. After enzymatic digestion, some slow bands were still visible. A second urine sample of the above 7 newborns was analyzed at the age of 1 month, demonstrating both a normal pattern and normal GAG levels. Additional urine and vaginal mucus samples from 10 term neonates with vaginal bleeding showed the same electrophoretic pattern observed in the 7 false positive samples. CONCLUSIONS: The altered electrophoretic pattern may be due to the presence of glycoproteins and not to specific GAGs, due to high levels of maternal hormones exposure during pregnancy. To our knowledge, this is the first time maternal estrogen hormones are proposed as a likely cause of false-positive urinary glycosaminoglycan screen test in healthy newborns.

Importance of the combined urinary procedure for the diagnosis of Mucopolysaccharidoses.

BACKGROUND: Mucopolysaccharidoses are characterized by the accumulation of undegraded glycosaminoglycans in lysosomes in multiple organs and by their excretion in high amounts in urine. The aim of this study is to determine if this simple, reliable and reproducible method is useful for the diagnosis of Mucopolysaccharidoses. METHODS: The study included 2154 normal urine samples and 210 samples from 73 patients affected by different types of Mucopolysaccharidoses. The glycosaminoglycans were quantified by a dimethylmethylene blue method and size-fractionated by a modified one-dimensional electrophoresis method. RESULTS: The combination of the two methods allowed to identify all the patients affected by the different types of Mucopolysaccharidosis with 100% sensitivity and specificity. CONCLUSION: This combined approach gives fast diagnostic orientation about the different types of Mucopolysaccharidoses, offering an important tool for a better understanding of diagnosis and patient management.

Total and single species of uronic acid-bearing glycosaminoglycans in urine of newborns of 2-3days of age for early diagnosis application.

BACKGROUND: Urine are easily accessible and relatively simple to process and uronic acid-bearing glycosaminoglycans (UA-GAGs) may serve as biomarkers for several diseases, like for mucopolysaccharidosis. METHODS: We report a study from a large cohort of healthy newborns of 2-3days to have a basic profile of total content of urinary UA-GAGs, their composition and structural signatures utilizing a rapid extractive method and sensitive separation of enzymatic released disaccharides by capillary electrophoresis-light induced fluorescence. Results were also compared with those obtained from normal adult subjects. RESULTS: A total of UA-GAGs content of ~35µg/mg creatinine was observed in 331 newborns versus 1.5µg/mg creatinine of adult urine composed of ~90% chondroitin sulfate (CS), ~7% heparan sulfate (HS) and ~3% hyaluronic acid (HA). No significant differences were observed with adults. Specific ratios between the main CS disaccharides were informative of a significant greater 4-sulfation and charge density for newborn compared to adults. The HS from newborn urine was mainly composed by the non-sulfated (~64%) and mono-sulfated (~28%) disaccharides. No significant differences were observed versus adult urine. CONCLUSIONS: The present method is able to measure changes in UA-GAG composition and their structure independently of the age of subjects and rapidly applicable to the newborn diagnosis without necessity to have creatinine levels. Moreover, modifications in charge density values as well as the presence of sulfate groups in specific positions may be indicative of altered conditions.