Recent advances in the applications of metabolomics in eye research

What is it about?

Metabolomics has been widely used to assess biological systems, providing molecular information related to phenotype since metabolites are ultimate product of gene, mRNA and protein activity. There is a growing number of metabolomics applications aiming to identify biomarkers for accurate diagnosis, providing therapy guidance and assessing therapy response. Monitoring biomarker levels in biological systems could greatly assist in detecting the early stages of disease development with improved sensitivity.

Featured Image

Why is it important?

The main analytical techniques adopted in global metabolomics analysis are nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). MS was usually hyphenated with different separation techniques, such as liquid chromatography (LC-MS) [6], gas chromatography (GC-MS) and capillary electrophoresis (CE-MS), to enhance sensitivity. CE coupled to other detectors, such as ultraviolet-laser induced fluorescence (UV-LIF) and UV, and Fourier transform-infrared (FT-IR) spectroscopy are less commonly used. The proton is the most commonly-studied nucleus for NMR studies. While NMR is a non-destructive technique requiring minimal sample preparation, even allowing for the analysis of intact tissue, sensitivity and metabolite resolution in NMR are limited compared to GC-MS or LC-MS. Hyphenated techniques combining separation and mass spectrometry-based (MS) detection are increasingly adopted as the analytical platform of choice in metabolomics studies. The proportion of published metabolomics studies with mentions of “GC-MS” or “LC-MS” (including LC-MS/MS) in their titles or abstracts has doubled over the past decade. GC-MS and LC-MS-based metabolomics studies may be performed using untargeted (global) or targeted strategies. In untargeted studies, prior knowledge of metabolites of interest is not essential as full scan MS data is acquired. Tandem MS (MS/MS) data for metabolite identification may be acquired in the same analysis with data-dependent acquisition (DDA, also known as information dependent acquisition), or in separate analyses. Following peak detection and alignment, and statistical analysis of full scan data, marker metabolites are putatively identified by accurate mass searches in metabolite databases, and confirmed by comparison of their retention time and MS/MS spectra with pure standards. In contrast, targeted studies are set up to analyze only specified metabolites. This is typically performed using multiple-reaction-monitoring (MRM) or neutral-loss (NL) scans on triple quadrupole or ion trap mass spectrometers. A comprehensive listing of mass spectra databases has also been published recently .

Perspectives