Abstract
Purpose :
The ocular surface (OS) is an easily accessible tissue allowing tears and cells to be collected for pathophysiological explorations. Lipids are important constituents of the structure of cell membranes and of the tear film. They are involved in various metabolisms, playing a role in signaling pathways especially cell proliferation and survival, cell migration, and calcium fluxes and participate in the antimicrobial defense of the OS. Our aim is to describe the lipid species composition of the ocular surface through the comparison of the main types of samples, Schirmer strip (ScS), conjunctival imprint (CI), tear fluid, and meibum.
Methods :
Ninety-six ocular surface samples were collected from both eyes of two subjects, once a week for six weeks, morning in a strict fasting state and one hour postprandial, using Sc, T, M and CI (Eyeprim® device) (24 samples each). A liquid-liquid extraction of lipids was performed, and extracts were analyzed by liquid chromatography hyphenated to high resolution tandem mass spectrometry. The identification of lipids species was carried out using molecular network strategy.
Results :
The qualitative analysis of the four eye samples allowed the identification of more than 500 lipid species: in Sc, 524, in T, 283, in M, 263 and in CI, 247 including 58 in common (glycerolipids, fatty acids and sterols). Non-polar lipids were detected in M and in Sc, while phosphatidylcholine and phosphatidylethanolamine (PE) were present in both CI, T and Sc. Moreover, lysophosphospholipid species were mainly retrieved in T. Finally, very long chain omega-3 fatty acids were found in M. No differences were observed between volunteers and time of sampling.
Conclusions :
Thanks to an exhaustive lipidomic analysis, our study highlights the specific signature of lipid species for each of the four collection methods studied. The lipid profile of the Sc, reflecting both the lipid composition of T, M and CI, appears to be the most effective collection method for the investigation of ocular surface lipids.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.