Meibum Lipid Composition in Asians with Dry Eye Disease

Abstract

BackgroundPrevious lipidomic analyses of the human meibum had largely focused on individuals from non-Asian populations, despite the higher prevalence of dysfunctional tear syndrome (DTS) observed across Asia. Information pertaining to the alterations in lipid profiles in relation to DTS onset and progression is also lacking and warrants comprehensive experimental analysis.Methodologies/Principal FindingsWe examined the meibum lipidome of 27 DTS patients and 10 control subjects for a total of 256 lipid species from 12 major lipid classes, including cholesteryl ester (CE), wax ester (WE), triacylglyceride (TAG), (O-acyl)-ω-hydroxy fatty acid (OAHFA), glycerophospholipids (phosphatidylcholine, PC; phosphatidylethanolamine, PE; phosphatidylinositol, PI; phosphatidylglycerol, PG) and sphingolipids (sphingomyelin, SM; ceramide, Cer; glucosylceramide, GluCer; dihexosylceramide, DihexCer). Neutral lipids were analysed using high-performance liquid-chromatography coupled with mass spectrometry (HPLC/MS) and tandem mass spectrometry (MS/MS) was used for the qualitative and quantitative analysis of polar lipid species. DTS patients were classified into three severity groups (i.e. mild, moderate and severe) based on the ocular surface disease index (OSDI). A significantly lower level of TAG (p<0.05) was observed in patients under the moderate category compared to the mild category. Notably, a number of OAHFA species displayed consistently decreasing levels that correlate with increasing disease severity. An attempt was also made to investigate the changes in meibum lipid profiles of DTS patients compared to normal individuals classified based on OSDI score. Several unsaturated TAG and PC species were found at significantly higher levels (p<0.05) in patients than controls.ConclusionThe current study presents, for the first time, a comprehensive lipidome of meibum from individuals of an Asian ethnicity, which can potentially offer new insights into the higher prevalence of DTS observed amongst Asian populations. This study also represents an attempt towards identification of lipid species in meibum which could serve as marker for DTS.

Intersubject and Interday Variability in Human Tear and Meibum Lipidomes: A Pilot Study

“…Lipid profiles of meibum are highly variable with 2-fold variation in CE abundance between individuals 11,21 . This high variability of lipid profiles has also been shown in the CE abundance in human tears 22 .…”

“…A comprehensive overview of the molecular lipid composition of human tears has recently been realized through application of contemporary mass-spectrometric analytical tools [10][11][12] . The advancements in instrumentation and extraction techniques have overcome challenges of small sample size and low overall lipid concentration, allowing the analysis of un-pooled samples, i.e.…”

Extensive characterization of human tear fluid collected using different techniques unravels the presence of novel lipid amphiphiles

“…We adhered to the tenets of the Declaration of Helsinki for all human research conducted in this study. The detailed clinical procedures have been reported elsewhere ( 10 ).…”

Accounting for Ethnicity-Related Differences in Ocular Surface Integrity as a Step Toward Understanding Contact Lens Discomfort

“…7,9,10 Specifically, some components of lens care solutions significantly alter dynamic interfacial properties and rheological behavior of human tear lipid films. [11][12][13] Clinical results suggest that both Asian and non-Asian groups exhibited increased corneal staining in response to biguanidepreserved solutions, although Asian subjects demonstrated greater sensitivity to the solutions than did non-Asian subjects. 4 However, the severity of ocular signs does not always correlate with overall lens wear comfort in Asian subjects, and thus may not be an impediment to overall satisfaction.…”

“…Studies conducted in China and Japan reported a much higher prevalence of dry eye syndrome (DES) than in previous reports, 12,13 suggesting that Asians may be more predisposed to DES than non-Asians. 11 In addition, Hispanic and Asian women in the United States were more likely to report severe dry eye symptoms when compared with white women. 77 Another research group came to a similar conclusion for Asian subjects.…”