Pamela Lavoie

Urinary Globotriaosylsphingosine-Related Biomarkers for Fabry Disease Targeted by Metabolomics

Fabry disease is a lysosomal storage disorder caused by deficiency of α-galactosidase A, resulting in glycosphingolipid accumulation in organs and tissues, including plasma and urine. Two disease-specific Fabry biomarkers have been identified and quantified in plasma and urine: globotriaosylceramide (Gb(3)) and globotriaosylsphingosine (lyso-Gb(3)). The search continues for biomarkers that might be reliable indicators of disease severity and response to treatment. The main objective of this study was to target other urinary biomarkers using a time-of-flight mass spectrometry metabolomic approach. Urinary metabolites of 63 untreated Fabry patients and 59 controls were analyzed. A multivariate statistical analysis performed on a subset of male samples revealed seven novel Fabry biomarkers in urine, all lyso-Gb(3) analogues having modified sphingosine moieties. The empirical formulas of the sphingosine modifications were determined by exact mass measurements (- C(2)H(4), - C(2)H(4) + O, - H(2), - H(2) + O, + O, + H(2)O(2), + H(2)O(3)). We evaluated the relative concentration of lyso-Gb(3) and its seven analogues by measuring area counts for each analogue in all Fabry patients. All samples were normalized to creatinine. We found higher concentrations for males with Fabry disease compared to females. None of these biomarkers were detected in controls. To our knowledge, this is the first time that lyso-Gb(3)-related Fabry disease biomarkers are detected in urine.

Multiplex Analysis of Novel Urinary Lyso-Gb3-Related Biomarkers for Fabry Disease by Tandem Mass Spectrometry

Fabry disease is a lysosomal storage disorder caused by the absence or reduction of α-galactosidase A enzyme activity. The enzymatic deficiency results in the impaired catabolism of neutral sphingolipids with terminal α-galactosyl residues and subsequent accumulation in several tissues. Biomarkers reflecting disease severity and progression, the response to therapeutic intervention, and details of molecular pathogenesis are needed. Until now, two sphingolipids were targeted as biomarkers in urine and plasma of Fabry patients: globotriaosylceramide (Gb(3)) and globotriaosylsphingosine (lyso-Gb(3)). Using metabolomic approaches, our group recently discovered seven novel urinary lyso-Gb(3)-related Fabry disease biomarkers with mass-to-charge ratios (m/z) of 758, 774, 784, 800, 802, 820, and 836. All these biomarkers exhibited modifications of the lyso-Gb(3) sphingosine moiety. The aims of the present study were to devise and validate a specific tandem mass spectrometry multiplex methodology for the relative quantification of these seven analogues and to evaluate their urinary excretion levels in samples from 164 Fabry patients and 94 healthy controls. We found no detectable analogues in healthy controls, except for trace amounts of the analogue with m/z 836. Significant correlations were established between lyso-Gb(3) analogue levels in urine and gender (p < 0.001). Fabry males had higher excretion levels compared to females with the disease. Lyso-Gb(3) analogue levels correlated well with enzyme replacement therapy (ERT) status in males (p < 0.05). The urinary analogue distributions varied among Fabry patients. However, the analogues with m/z 802, 820, and 836 were generally more abundant in the majority of patients. Lyso-Gb(3) analogues are promising urinary biomarkers for Fabry disease.

An improved method for glycosaminoglycan analysis by LC–MS/MS of urine samples collected on filter paper

BACKGROUND Mucopolysaccharidoses are complex lysosomal storage disorders caused by any of eleven different enzyme deficiencies resulting in the accumulation of substrates, mainly glycosaminoglycans (GAGs), in various tissues and biological fluids. METHOD We developed and validated a urine filter paper methodology for the analysis of GAGs using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for mucopolysaccharidoses type I, type II and type VI patients. We focused on 2 objectives: first, its applicability to high-risk screening, and secondly, to facilitate the collection and shipping of samples to reference centers as part of diagnostic investigation, as well as from treated patients needing to be monitored for assessment of the efficacy of treatment. GAGs in urine dried onto filter paper were extracted and subjected to methanolysis to obtain the repeating disaccharides of the molecules. We devised a multiple reaction monitoring method in positive electrospray ionization mode. RESULTS The use of deuterated internal standards for dermatan sulfate (DS) and heparan sulfate (HS) reduced a troubling matrix effect. The resulting CVs were <14%. Linearity assessment showed Pearson correlation coefficients of 0.999 and 0.997, for DS and HS, respectively. The stability on filter paper was good for DS and HS for up to 6 weeks at various temperatures. CONCLUSION We devised a robust and efficient LC-MS/MS methodology for GAGS quantification in urine dried on filter paper and subjected to environmental conditions likely to be encountered during collection, storage and shipping of specimens from referring physicians to medical centers.

LC-MS/MS analysis of plasma lyso-Gb3 in Fabry disease.

BACKGROUND Fabry disease is a complex, multisystemic and clinically heterogeneous disease, with elevated excretion of globotriaosylceramide (Gb(3)) and globotriaosylsphingosine (lyso-Gb(3)) accumulating in biological fluids caused by deficiency of the enzyme, lysosomal α-galactosidase A. Our aims were to propose a tandem mass spectrometry fragmentation mechanism for lyso-Gb(3), to develop and validate a simple, and robust methodology for the measurement of plasma lyso-Gb(3) using LC-MS/MS in large Fabry cohorts and in controls. Response to treatment was also evaluated. METHOD A solid-phase extraction procedure was used to process plasma samples. The 1-β-D-glucosylsphingosine (GSG) internal standard was chosen for its commercial availability. A liquid chromatography method was devised to allow the co-elution of the GSG internal standard with lyso-Gb(3), thus compensating for system variability and reducing the matrix effect. A multiple reaction monitoring method was developed, working in positive electrospray ionization. RESULTS The validation of the method provided good accuracy and precision: intraday and interday biases of less than 8% and 5%, respectively, and intraday and interday CVs of <12% and 7%, respectively. Limit of detection was 0.7 nmol/l and limit of quantification was 2.5 nmol/l. Plasma samples were stable for up to 6h at room temperature, 48 h at 4 °C, and 20 weeks at -20 °C. Regarding untreated Fabry patients, the mean lyso-Gb(3) concentrations were 170 nmol/l for males and 9.7 nmol/l for females, and for treated patients, 40.2 nmol/l for males and 7.5 nmol/l for females. CONCLUSION A robust LC-MS/MS methodology is presented for plasma lyso-Gb(3) quantification.

Urinary biomarker investigation in children with Fabry disease using tandem mass spectrometry.

BACKGROUND Fabry disease is an X-linked lysosomal storage disorder affecting both males and females with tremendous genotypic/phenotypic variability. Concentrations of globotriaosylceramide (Gb3), globotriaosylsphingosine (lyso-Gb3)/related analogues were investigated in pediatric and adult Fabry cohorts. The aims of this study were to transfer and validate an HPLC-MS/MS methodology on a UPLC-MS/MS new generation platform, using an HPLC column, for urine analysis of treated and untreated pediatric and adult Fabry patients, to establish correlations between the excretion of Fabry biomarkers with gender, treatment, types of mutations, and to evaluate the biomarker reliability for early detection of pediatric Fabry patients. METHOD A UPLC-MS/MS was used for biomarker analysis. RESULTS Reference values are presented for all biomarkers. Results show that gender strongly influences the excretion of each biomarker in the pediatric Fabry cohort, with females having lower urinary levels of all biomarkers. Urinary distribution of lyso-Gb3/related analogues in treated Fabry males was similar to the untreated and treated Fabry female groups in both children and adult cohorts. Children with the late-onset p.N215S mutation had normal urinary levels of Gb3, and lyso-Gb3 but abnormal levels of related analogues. CONCLUSIONS In this study, Fabry males and most Fabry females would have been diagnosed using the urinary lyso-Gb3/related analogue profile.

Tandem mass spectrometry multiplex analysis of methylated and non-methylated urinary Gb3 isoforms in Fabry disease patients.

BACKGROUND Fabry disease is a lysosomal storage disorder leading to the accumulation of glycosphingolipids in biological fluids and tissues. Globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3) are currently used for Fabry screening and diagnosis. However, these biomarkers are not always increased in Fabry patients with residual enzyme activity. We recently identified 7 urinary methylated Gb3-related isoforms. The aims of this study were (1) to develop and validate a novel LC-MS/MS method for the relative quantification of methylated and non-methylated Gb3 isoforms normalized to creatinine, (2) to evaluate these biomarkers in Fabry patients and healthy controls, and (3) to assess correlations between biomarker urinary excretion with age, gender, treatment and genotype of patients. METHODS Urine samples from 150 Fabry patients and 95 healthy controls were analyzed. Samples were purified and injected in the tandem mass spectrometer working in positive electrospray ionization. Relative quantification was performed for 15 methylated and non-methylated Gb3 isoforms. RESULTS Significant correlations (p<0.001) were established between Gb3 isoform concentrations, gender and treatment. Five patients with the late-onset cardiac mutation p.N215S showed abnormal concentrations of methylated Gb3 isoforms compared to their non-methylated homologues. CONCLUSIONS Methylated Gb3 isoforms might be helpful urinary biomarkers for Fabry patients with late-onset cardiac variant mutations.

Evaluation of urinary keratan sulfate disaccharides in MPS IVA patients using UPLC–MS/MS

BACKGROUND Glycosaminoglycan analysis for the diagnosis of Morquio patients has been daunting due to lack of sensitivity/specificity of the dimethylmethylene blue-based spectrophotometry methodology, routinely used by several clinical laboratories. MS methods have been devised for quantification of keratan sulfate for Morquio patients, but some used tributylamine in mobile phases, or did not use isotope-labeled internal standards. Results & methodology: An UPLC-MS/MS methodology aiming to solve these issues was devised, based on the digestion of keratan sulfate to obtain two major disaccharides. Abnormal urinary results were obtained for all Morquio A patients, while the dimethylmethylene blue-based spectrophotometry methodology showed normal results for four out of nine cases. CONCLUSION The devised method is sensitive, specific and suitable for high-risk screening and longitudinal evaluation of treated patients.

Variations in the GLA gene correlate with globotriaosylceramide and globotriaosylsphingosine analog levels in urine and plasma

Recent data have shown that lyso-Gb3, the deacylated derivative of globotriaosylceramide (Gb3), is possibly involved in the pathogenesis of Fabry disease (FD) and might be a clinically useful biomarker of its metabolic load. To test this hypothesis, we assayed Gb3 and lyso-Gb3 and related analogs in plasma and/or urine samples of 12 clinically well-characterized subjects carrying several different GLA variant alleles associated with a wide range of residual α-galactosidase A activities. Urinary Gb3 was measured by HPLC-MS/MS; plasma and urinary lyso-Gb3 and related analogs were measured by UPLC-MS/MS. Individual profiles of Gb3 and lyso-Gb3 and related analogs closely correlated with the phenotypic data for each subject, discerning the classical FD patient from the two patients carrying cardiac variants as well as those from all the others without FD. The lyso-Gb3 analog at m/z 836 was found at increased levels only in patients manifesting clinically severe heart disease, irrespective of the pathogenicity of the GLA variant they carried. This finding suggests that this lyso-Gb3 analog might be an earlier biomarker of progressive heart disease, non-specific of the FD cardiomyopathy. The possibility that urinary Gb3 is a specific marker of kidney involvement in FD deserves further study.

Biomarkers associated with clinical manifestations in Fabry disease patients with a late-onset cardiac variant mutation.

BACKGROUND Fabry disease is a lysosomal storage disorder with an incidence of 1:1600 for the late-onset IVS4+919G>A cardiac variant mutation in Taiwan. Signs and symptoms of this cardiac variant include left ventricular hypertrophy, mitral insufficiency and/or arrhythmias. The search for biomarkers that might predict the clinical outcomes and guide treatment options is important. We thus investigated relationships between Fabry disease biomarkers (such as globotriaosylceramide (Gb3), globotriaosylsphingosine (lyso-Gb3)/related analogues) and age, gender, enzyme activity, clinical manifestations and severity of the disease in these patients. METHOD Urine and plasma biomarkers were analyzed using tandem mass spectrometry. A large cohort of 191 adult and pediatric Fabry patients carrying the IVS4+919G>A mutation was studied. Some patients were members of the same family. RESULTS Our results show that the plasma lyso-Gb3 level, and urinary analogue levels of lyso-Gb3 at m/z (+16), (+34), and (+50) adjusted for gender and age had a positive association with the left ventricular mass index, and/or the Mainz Severity Score Index. CONCLUSIONS It might thus be of particular interest to monitor children with high levels of these biomarkers, as part of a longitudinal study in order to determine if the excretion profile at a young age is predictive of the outcomes of disease severity in adulthood.

High-throughput tandem mass spectrometry multiplex analysis for newborn urinary screening of creatine synthesis and transport disorders, Triple H syndrome and OTC deficiency.

BACKGROUND Creatine synthesis and transport disorders, Triple H syndrome and ornithine transcarbamylase deficiency are treatable inborn errors of metabolism. Early screening of patients was found to be beneficial. Mass spectrometry analysis of specific urinary biomarkers might lead to early detection and treatment in the neonatal period. We developed a high-throughput mass spectrometry methodology applicable to newborn screening using dried urine on filter paper for these aforementioned diseases. METHODS A high-throughput methodology was devised for the simultaneous analysis of creatine, guanidineacetic acid, orotic acid, uracil, creatinine and respective internal standards, using both positive and negative electrospray ionization modes, depending on the compound. RESULTS The precision and accuracy varied by <15%. Stability during storage at different temperatures was confirmed for three weeks. The limits of detection and quantification for each biomarker varied from 0.3 to 6.3 μmol/l and from 1.0 to 20.9 μmol/l, respectively. Analyses of urine specimens from affected patients revealed abnormal results. Targeted biomarkers in urine were detected in the first weeks of life. CONCLUSIONS This rapid, simple and robust liquid chromatography/tandem mass spectrometry methodology is an efficient tool applicable to urine screening for inherited disorders by biochemical laboratories.