Background Fabry disease is a progressive multisystemic disease, which affects the kidney and cardiovascular systems. Various treatments exist but decisions on how and when to treat are contentious. The current marker for monitoring treatment is plasma globotriaosylsphingosine (lyso-Gb3), but it is not informative about the underlying and developing disease pathology.
Methods We have created a urine proteomic assay containing a panel of biomarkers designed to measure disease-related pathology which include the inflammatory system, lysosome, heart, kidney, endothelium and cardiovascular system. Using a targeted proteomic-based approach, a series of 40 proteins for organ systems affected in Fabry disease were multiplexed into a single 10 min multiple reaction monitoring Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) assay and using only 1 mL of urine.
Results Six urinary proteins were elevated in the early-stage/asymptomatic Fabry group compared with controls including albumin, uromodulin, α1-antitrypsin, glycogen phosphorylase brain form, endothelial protein receptor C and intracellular adhesion molecule 1. Albumin demonstrated an increase in urine and could indicate presymptomatic disease. The only protein elevated in the early-stage/asymptomatic patients that continued to increase with progressive multiorgan involvement was glycogen phosphorylase brain form. Podocalyxin, fibroblast growth factor 23, cubulin and Alpha-1-Microglobulin/Bikunin Precursor (AMBP) were elevated only in disease groups involving kidney disease. Nephrin, a podocyte-specific protein, was elevated in all symptomatic groups. Prosaposin was increased in all symptomatic groups and showed greater specificity (p<0.025–0.0002) according to disease severity.
Conclusion This work indicates that protein biomarkers could be helpful and used in conjunction with plasma lyso-Gb3 for monitoring of therapy or disease progression in patients with Fabry disease.
- Fabry disease
- mass spectrometry
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IDD and WEH are joint first authors.
AN and KM are joint last authors.
AN and KM contributed equally.
Contributors IDD and WEH, the main authors, contributed equally to study design, the design of peptides, development and optimisation of the digestion and clean up of peptides, the method development, the data analyses and writing of the manuscript. This is the PhD work of IDD. VN, JS and JH helped carry out the laboratory work, for example, extraction of the proteins from the urines, digestion and clean up of the peptides for analyses, running of the mass spectrometer and significant help doing blinded data analyses for significant amounts of ‘peak picking’ and calibration lines creation, that is, integrating protein chromatograms and graph drawing. PTC, PM, DGW are our colleagues, consultant medics, nephrologists and biochemists who provided advise and guidance on what proteins to look at that we should look at as biomarkers of endothelium, lysosomes, cardiac cells, immunity and kidney disease. They were all involved in the study design, how to write the paper and then critical assessment of the final manuscript and conclusions. KM and AN were instrumental in study design, idea of the method development and writing of the manuscript. AN was the clinician involved in seeing all the patients, collecting samples, providing clinical data and diagnoses. KM is the head of mass spectrometry group carrying out this work and was involved in all stages of the analyses, from the initial idea to look at a new way in stratifying patients with FD using urine proteomics, advice of all aspects of the method development, discussion of the results, paper structure and in the writing of the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Disclaimer The views expressed are those of the author(s) and not necessarily those of the National Health Service, the NIHR or the Department of Health.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The study was conducted in accordance with the principles of the Declaration of Helsinki and approved by the Ethics committee of the canton of Zurich, Switzerland (KEK-ZH 2017-00386).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available on reasonable request. All data relevant to the study are included in the article or uploaded as supplementary information.