Urinary Mass Spectrometry Profiles in Age-Related Macular Degeneration

Abstract

We and others have shown that patients with different severity stages of age-related macular degeneration (AMD) have distinct plasma metabolomic profiles compared to controls. Urine is a biofluid that can be obtained non-invasively and, in other fields, urine metabolomics has been proposed as a feasible alternative to plasma biomarkers. However, no studies have applied urinary mass spectrometry (MS) metabolomics to AMD. This study aimed to assess urinary metabolomic profiles of patients with different stages of AMD and a control group. We included two prospectively designed, multicenter, cross-sectional study cohorts: Boston, US (n = 185) and Coimbra, Portugal (n = 299). We collected fasting urine samples, which were used for metabolomic profiling (Ultrahigh Performance Liquid chromatography—Mass Spectrometry). Multivariable logistic and ordinal logistic regression models were used for analysis, accounting for gender, age, body mass index and use of AREDS supplementation. Results from both cohorts were then meta-analyzed. No significant differences in urine metabolites were seen when comparing patients with AMD and controls. When disease severity was considered as an outcome, six urinary metabolites differed significantly (p < 0.01). In particular, two of the metabolites identified have been previously shown by our group to also differ in the plasma of patients of AMD compared to controls and across severity stages. While there are fewer urinary metabolites associated with AMD than plasma metabolites, this study identified some differences across stages of disease that support previous work performed with plasma, thus highlighting the potential of these metabolites as future biomarkers for AMD.

Recent Advances in Proteomics-Based Approaches to Studying Age-Related Macular Degeneration: A Systematic Review

“…Based on all this, urine has also been used, in recent years, as a non-invasive easy-to-collect source for biomarker discovery, with the aim of identifying not only the metabolomic [ 138 , 139 ], but also the proteomic signature of the different sub-types of AMD. A tandem mass tagged (TMT) approach identified panels of proteins characteristic of eAMD, GA and nAMD [ 83 ].…”

Integrating genetics and metabolomics from multi-ethnic and multi-fluid data reveals putative mechanisms for age-related macular degeneration

“…The detailed study protocol for blood and urine samples have been described elsewhere. 19 , 55 In summary, patients diagnosed with AMD, as well as participants with no evidence of AMD, aged more than 50 years were included at both study sites (Boston and Portugal) and underwent a complete ophthalmological exam for phenotypic characterization. For all participants, overnight fasting samples were collected the next morning.…”

“… 19 We also collected urine samples into sterile cups and then stored into sterile cryovials of 1.5 mL (MEE) and 5 mL (FMUC/AIBILI), which were stored at −80°. 55 …”

“…The non-targeted MS analysis (UPLC-MS/MS) was used for metabolomic profiling by Metabolon. 19 , 55 The standard quality control and data processing pipeline were used for metabolite measurements, with 907 plasma metabolites and 1,417 urine metabolites included in the current analysis after batch normalization. Briefly, we removed metabolites with missing rate >50% or no variance.…”

Recent Advances in Proteomic-based Approaches to Study Age-related Macular Degeneration: A Systematic Review

“…Based on all this, urine has also been used, in the last years, as a non-invasive easyto-collect source for biomarker discovery with the aim of identifying not only the metabolomic [137,138], but also the proteomic signature of the different sub-types of AMD. A tandem mass tagged (TMT) approach identified panels of proteins characteristic of eAMD, GA and nAMD [139].…”