LC-MS/MS method for simultaneous quantification of heparan sulfate and dermatan sulfate in urine by butanolysis derivatization

Glycosaminoglycans: Participants in Microvascular Coagulation of Sepsis

Sepsis represents a syndromic response to infection and frequently acts as a common pathway leading to fatality in the context of various infectious diseases globally. The pathology of severe sepsis is marked by an excess of inflammation and activated coagulation. A substantial contributor to mortality in sepsis patients is widespread microvascular thrombosis-induced organ dysfunction. Multiple lines of evidence support the notion that sepsis induces endothelial damage, leading to the release of glycosaminoglycans, potentially causing microvascular dysfunction. This review aims to initially elucidate the relationship among endothelial damage, excessive inflammation, and thrombosis in sepsis. Following this, we present a summary of the involvement of glycosaminoglycans in coagulation, elucidating interactions among glycosaminoglycans, platelets, and inflammatory cells. In this section, we also introduce a reasoned generalization of potential signal pathways wherein glycosaminoglycans play a role in clotting. Finally, we discuss current methods for detecting microvascular conditions in sepsis patients from the perspective of glycosaminoglycans. In conclusion, it is imperative to pay closer attention to the role of glycosaminoglycans in the mechanism of microvascular thrombosis in sepsis. Dynamically assessing glycosaminoglycan levels in patients may aid in predicting microvascular conditions, enabling the monitoring of disease progression, adjustment of clinical treatment schemes, and mitigation of both acute and long-term adverse outcomes associated with sepsis.

Biomarkers for gene therapy clinical trials of lysosomal storage disorders

Lysosomal storage disorders (LSDs) are multisystemic progressive disorders caused by defects in proteins involved in lysosomal function. Different gene therapy strategies are under clinical investigation in several LSDs to overcome the limitations of available treatments. However, LSDs are slowly progressive diseases that require long-term studies to establish the efficacy of experimental treatments. Biomarkers can be reliable substitutes for clinical responses and improve the efficiency of clinical trials, especially when long-term disease interventions are evaluated. In this review, we summarize both available and future biomarkers for LSDs and discuss their strengths and weaknesses.

Application of tandem mass spectrometry in the screening and diagnosis of mucopolysaccharidoses

Mucopolysaccharidoses (MPSs) are caused by a deficiency in the enzymes needed to degrade glycosaminoglycans (GAGs) in the lysosome. The storage of GAGs leads to the involvement of several systems and even to the death of the patient. In recent years, an increasing number of therapies have increased the treatment options available to patients. Early treatment is beneficial in improving the prognosis, but children with MPSs are often delayed in their diagnosis. Therefore, there is an urgent need to develop a method for early screening and diagnosis of the disease. Tandem mass spectrometry (MS/MS) is an analytical method that can detect multiple substrates or enzymes simultaneously. GAGs are reliable markers of MPSs. MS/MS can be used to screen children at an early stage of the disease, to improve prognosis by treating them before symptoms appear, to evaluate the effectiveness of treatment, and for metabolomic analysis or to find suitable biomarkers. In the future, MS/MS could be used to further identify suitable biomarkers for MPSs for early diagnosis and to detect efficacy.

Endogenous, non-reducing end glycosaminoglycan biomarkers for the mucopolysaccharidoses: Accurate diagnosis and elimination of false positive newborn screening results

The mucopolysaccharidoses (MPS) are a family of inborn errors of metabolism resulting from a deficiency in a lysosomal hydrolase responsible for the degradation of glycosaminoglycans (GAG). From a biochemical standpoint, excessive urinary excretion of GAG has afforded first-tier laboratory investigations for diagnosis whereas newborn screening programs employ lysosomal hydrolase measurements. Given false positives are not uncommon, second-tier diagnostic testing relies on lysosomal hydrolase measurements following elevated urinary GAG, and newborn screening results are often corroborated with GAG determinations. Molecular genetics requires acknowledgement, as identifying pathogenic variants in the hydrolase genes confirms the diagnosis and allows cascade testing for families, but genetic variants of uncertain significance complicate this paradigm. Initiating cellular, tissue and organ damage that leads to an MPS phenotype is undoubtedly the accumulation of partially degraded GAG, and with mass spectrometry technologies now readily available in the biochemical genetics' laboratory, the ability to properly measure these GAG fragments has been realized. The most common approach involves bacterial lyase/hydrolase digestion of the long chain GAG polymers into their disaccharide units that can be measured by mass spectrometry. Another, less well-known method, the endogenous, non-reducing end method, does not require depolymerization of GAG but rather relies on the mass spectrometric measurement of the naturally produced oligosaccharides that arise from the enzyme deficiency. All MPS can be identified by this one method, and evidence to date shows it to be the only GAG analysis method that gives no false positives when employed as a first-tier laboratory diagnostic test and second-tier newborn screening test.

Detection of Glycosaminoglycans in Biological Specimens

Proteoglycans (PGs) are macromolecules formed by a protein backbone to which one or more glycosaminoglycan (GAG) side chains are covalently attached. Most PGs are present in connective tissues, cell surfaces, and intracellular compartments. The major biological function of PGs derives from the GAG component of the molecule, which is involved in cell growth and proliferation, embryogenesis, maintenance of tissue hydration, and interactions of the cells via receptors. PGs are categorized into four groups based on their cellular and subcellular localization, including cell surfaces and extracellular, intracellular, and pericellular locations. GAGs are a crucial component of PGs involved in various physiological and pathological processes. GAGs also serve as biomarkers of metabolic diseases such as mucopolysaccharidoses and mucolipidoses. Detection of specific GAGs in various biological fluids helps manage various genetic metabolic disorders before it causes irreversible damage to the patient (Amendum et al., Diagnostics (Basel) 11(9):1563, 2021). There are several methods for detecting GAGs; this chapter focuses on measuring GAGs using enzyme-linked immunosorbent assay, liquid chromatographic tandem mass spectrometry, and automated high-throughput mass spectrometry.

Mass spectrometry and two-dimensional electrophoresis in prenatal diagnosis of mucopolysaccharidosis type VI

Background

Mucopolysaccharidosis VI (MPS VI) or Maroteaux–Lamy syndrome is an autosomal recessive lysosomal storage disorder. Clinical manifestations are related to progressive accumulation of dermatan sulfate (DS). Two-dimensional electrophoresis has traditionally been used for the diagnosis of MPS disorders. The method is only qualitative and is time consuming. For prenatal diagnosis of MPS, 6–8 ml of amniotic fluid is required and 5 working days to complete. It needs personal experience to do the test and to interpret the results. Mass spectrometry (MS) is now available as a quantitative method and for prenatal diagnosis of MPS it needs less amniotic fluid and takes only 2 working days. It is more accurate, less person dependent, but it costs more. Our aim was to introduce quantitative determination of dermatan sulfate using mass spectrometry in the prenatal diagnosis of MPS VI in Egypt and to compare this technique to the classical qualitative diagnosis using two-dimensional electrophoresis (2-DEP) of the glycosaminoglycans (GAGs) in amniotic fluid. Thirty pregnant females each with single fetus were subjected to amniocentesis at 16 weeks gestation. Ten with a previously affected MPS VI infant and twenty served as controls. Prenatal diagnosis (PD) was done by both MS and 2-DEP.

Results

MS verified 2-DEP results which showed 5 affected and 5 non-affected fetuses with MPS VI.

Conclusion

Two-dimensional electrophoresis of the GAGs in amniotic fluid is a good qualitative method and MS was an accurate quantitative method for prenatal diagnosis of MPS type VI. Quantitative determination of GAGs in AF by mass spectrometry is quicker. Where prenatal diagnosis is recommended for at risk pregnancies, mass spectrometry could be used more in the future as it gives rapid and accurate results.

Diagnosis of Mucopolysaccharidoses and Mucolipidosis by Assaying Multiplex Enzymes and Glycosaminoglycans

Mucopolysaccharidoses (MPS) and mucolipidosis (ML II/III) are a group of lysosomal storage disorders (LSDs) that occur due to a dysfunction of the lysosomal hydrolases responsible for the catabolism of glycosaminoglycans (GAGs). However, ML is caused by a deficiency of the enzyme uridine-diphosphate N-acetylglucosamine:lysosomal-enzyme-N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase, EC2.7.8.17), which tags lysosomal enzymes with a mannose 6-phosphate (M6P) marker for transport to the lysosome. A timely diagnosis of MPS and ML can lead to appropriate therapeutic options for patients. To improve the accuracy of diagnosis for MPS and ML in a high-risk population, we propose a combination method based on known biomarkers, enzyme activities, and specific GAGs. We measured five lysosomal enzymes (α-L-iduronidase (MPS I), iduronate-2-sulfatase (MPS II), α-N-acetylglucosaminidase (MPS IIIB), N-acetylglucosamine-6-sulfatase (MPS IVA), and N-acetylglucosamine-4-sulfatase (MPS VI)) and five GAGs (two kinds of heparan sulfate (HS), dermatan sulfate (DS), and two kinds of keratan sulfate (KS)) in dried blood samples (DBS) to diagnose suspected MPS patients by five-plex enzyme and simultaneous five GAGs assays. We used liquid chromatography-tandem mass spectrometry (LC-MS/MS) for both assays. These combined assays were tested for 43 patients with suspected MPS and 103 normal control subjects. We diagnosed two MPS I, thirteen MPS II, one MPS IIIB, three MPS IVA, two MPS VI, and six ML patients with this combined method, where enzymes, GAGs, and clinical manifestations were compatible. The remaining 16 patients were not diagnosed with MPS or ML. The five-plex enzyme assay successfully identified MPS patients from controls. Patients with MPS I, MPS II, and MPS IIIB had significantly elevated HS and DS levels in DBS. Compared to age-matched controls, patients with ML and MPS had significantly elevated mono-sulfated KS and di-sulfated KS levels. The results indicated that the combination method could distinguish these affected patients with MPS or ML from healthy controls. Overall, this study has shown that this combined method is effective and can be implemented in larger populations, including newborn screening.

Podocyte sphingomyelin phosphodiesterase acid-like 3b decreases among children with idiopathic nephrotic syndrome

AIM

Sphingomyelin phosphodiesterase acid-like 3b (SMPDL-3b), a regulator of the cytoskeleton, is expressed on podocytes. Recent reports present evidence that it is directly targeted by rituximab in the treatment of intractable nephrotic syndrome. However, the implications of SMPDL-3b for treatment of paediatric-onset idiopathic nephrotic syndrome (INS) remain unclear. This study aimed to investigate the level of expression of SMPDL-3b in urine, serum, and biopsy specimens and explore its implications in treatment of patients with INS.

METHODS

Levels of urinary SMPDL-3b among 31 patients (20 in remission and 11 in relapse) with INS were analysed by dot blotting. For reference of precise quantitative analysis, we examined urinary excretion of SMPDL-3b from 10 patients with INS by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in both remitted and relapsed status. The levels of serum SMPDL-3b among 20 patients (13 in remission and 7 in relapse or onset) with INS were also measured using enzyme-linked immunosorbent assay. Further, the immunoreactivity of SMPDL-3b in the biopsy specimens obtained from patients with INS was compared with those from patients with proteinuric IgA nephropathy, lupus nephritis, and non-proteinuric controls.

RESULTS

Urinary excretion of SMPDL-3b in patients with INS was significantly decreased in relapse cases compared with cases of remission and other types of proteinuric glomerular disease or controls by both dot blotting and LC-MS/MS method. On the other hand, serum SMPDL-3b level in INS was not different between cases of remission and relapse. Glomerular immunoreactivity of SMPDL-3b in patient with INS in remission was almost the same level to that of control.

CONCLUSION

The expression of SMPDL-3b on podocytes is specifically decreased in paediatric-onset INS and its urinary excretion level reflects such conditions.

Highlights on Genomics Applications for Lysosomal Storage Diseases

Lysosomal storage diseases (LSDs) are a heterogeneous group of rare multisystem genetic disorders occurring mostly in infancy and childhood, characterized by a gradual accumulation of non-degraded substrates inside the lysosome. Although the cellular pathogenesis of LSDs is complex and still not fully understood, the approval of disease-specific therapies and the rapid emergence of novel diagnostic methods led to the implementation of extensive national newborn screening (NBS) programs in several countries. In the near future, this will help the development of standardized workflows aimed to more timely diagnose these conditions. Hereby, we report an overview of LSD diagnostic process and treatment strategies, provide an update on the worldwide NBS programs, and discuss the opportunities and challenges arising from genomics applications in screening, diagnosis, and research.

Quantitative analysis of heparan sulfate using isotopically labeled calibrants

Heparan sulfate is a sulfated polysaccharide that displays essential physiological functions. Here, we report a LC-MS/MS-based method for quantitatively determining the individual disaccharide composition and total amount of heparan sulfate. Using eight ¹³C-labeled disaccharide calibrants and one ¹³C-labeled polysaccharide calibrant, we complete the analysis in one-pot process. The method is both sensitive and has the throughput to analyze heparan sulfate from mouse tissues and plasma.

Wang et al. describe a strategy for quantitatively performing composition analysis of heparan sulfate using ¹³C-labeled disaccharides and polysaccharides that mimic the glycosaminoglycan chemical structure. They further show that these isotopically labelled small molecules can be used as internal standards for mass spectrometry analysis of heparan sulfate derived from mouse tissue and plasma.

Advances in glycosaminoglycan detection

BACKGROUND

Glycosaminoglycans (GAGs) are negatively charged long linear (highly sulfated) polysaccharides consisting of repeating disaccharide units that are expressed on the surfaces of all nucleated cells. The expression of GAGs is required for embryogenesis, regulation of cell growth and proliferation, maintenance of tissue hydration, and interactions of the cells via receptors. Mucopolysaccharidoses (MPS) are caused by deficiency of specific lysosomal enzymes that result in the accumulation of GAGs in multiple tissues leading to organ dysfunction. Therefore, GAGs are important biomarkers for MPS. Without any treatment, patients with severe forms of MPS die within the first two decades of life.

SCOPE OF REVIEW

Accurate measurement of GAGs is important to understand the diagnosis and pathogenesis of MPS and to monitor therapeutic efficacy before, during, and after treatment of the disease. This review covers various qualitative and quantitative methods for measurement of GAGs, including dye specific, thin layer chromatography (TLC), capillary electrophoresis, high-performance liquid chromatography (HPLC), liquid chromatography-tandem mass spectrometry (LC-MS/MS), gas chromatography, ELISA, and automated high-throughput mass spectrometry. Major conclusion: There are several methods for GAG detection however, specific GAG detection in the various biological systems requires rapid, sensitive, specific, and cost-effective methods such as LC-MS/MS.

GENERAL SIGNIFICANCE

This review will describe different methods for GAG detection and analysis, including their advantages and limitation.

Mucopolysaccharidosis type II (Hunter syndrome): Clinical and biochemical aspects of the disease and approaches to its diagnosis and treatment

Mucopolysaccharidosis type II (MPS II, Hunter syndrome) is a rare X-linked lysosomal storage disease caused by mutations of the gene encoding the lysosomal enzyme iduronate-2-sulfatase (IDS), the role of which is to hydrolytically remove O-linked sulfates from the two glycosaminoglycans (GAGs) heparan sulfate (HS) and dermatan sulfate (DS). HS and DS are linear, heterogeneous polysaccharides composed of repeating disaccharide subunits of l-iduronic acid (IdoA) or d-glucuronic acid, (1→4)-linked to d-glucosamine (for HS), or (1→3)-linked to 2-acetamido-2-deoxy-d-galactose (N-acetyl-d-galactosamine) (for DS). In healthy cells, IDS cleaves the sulfo group found at the C-2 position of terminal non-reducing end IdoA residues in HS and DS. The loss of IDS enzyme activity leads to progressive lysosomal storage of HS and DS in tissues and organs such as the brain, liver, spleen, heart, bone, joints and airways. Consequently, this leads to the phenotypic features characteristic of the disease. This review provides an overview of the disease profile and clinical manifestation, with a particular focus on the biochemical basis of the disease and chemical approaches to the development of new diagnostics, as well as discussing current treatment options and emerging new therapies.

Proteomic approaches in the discovery of potential urinary biomarkers of mucopolysaccharidosis type II

Mucopolysaccharindosis type II (MPS II) is a rare lysosomal storage disorder caused by deficient or absent activity of the iduronate-2-sulfatase (IDS) enzyme, which leads to pathological accumulation of the glycosaminoglycans(GAGs). The absence of early diagnosis can result in irreversible developmental, neurological, and physiological damage. The lack of clear understanding of the etiology of physiological dysfunction in MPS II has been a major obstacle to the development of new treatment. Therefore, a reliable biomarker for early diagnosis and exploration of pathogenic mechanism are of great importance. Proteomics provides powerful tool for protein expression alterations and study of complicated pathological process. This study was performed to identify the differential protein profile in urine of MPS II patients using two-dimensional gel electrophoresis(2D-PAGE)combining with MALDI-TOF/TOF and a total of 15 differentially expressed proteins were identified. Content of alpha1-antitrypsin, Gm2 activator and lipocalin-type prostaglandin D synthase was measured by ELISA method. The value of urinary α1-AT/Cr in MPS II group was 0.79 ± 0.10 mg/mmol, significantly higher than 0.42 ± 0.05 mg/mmol in healthy control group; whereas the value of GM2A/Cr and L-PGDS/Cr in MPS II group was 1.30 ± 0.12 μg/mmol and 9.86 ± 1.16 ng/mmol respectively, which was significantly lower than 2.19 ± 0.19 μg/mmol and 13.98 ± 1.48 ng/mmol in healthy control group. The proteins can be considered as accessory diagnostic biomarkers for MPS II. This approach helped to discover early diagnostic markers and provided a better understanding of the pathogenic mechanism of MPS II.

Data in support for the measurement of heparan sulfate and dermatan sulfate by LC-MS/MS analysis

This article provides supplementary data for the paper “LC–MS/MS method for simultaneous quantification of heparan sulfate and dermatan sulfate in urine by butanolysis derivatization” (Forni et al., 2018). Several parameters were tested to optimize sample preparation by butanolysis in order to carry out simultaneous quantifications of HS and DS by tandem mass spectrometry.

Here we describe step-by-step instructions to perform HS and DS analysis in urine samples using external calibration curves of standards of known concentration. Sample are quantified by interpolation from the calibration curve and reported in µg/mL. Then, HS and DS are normalized to creatinine concentration and reported as mg/g uCr.