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Igor A Butovich, Nita Bhat, Tomo Suzuki, Shigeru Kinoshita, Jadwiga Wojtowicz; Establishing the baselines for genomic and lipidomic analyses of human meibomian glands. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5676. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Adverse changes in Meibomian glands (MG) in general, and in quality of meibum and the tear film specifically, were linked to various ocular surface diseases, such as Dry Eye (DE) and MG dysfunction, among others. Also, DE has been shown to preferentially affect women, implying that sex may be a contributing factor. However, the exact nature and causes of changes in meibum in those conditions remain largely elusive. Another understudied area is the effect of race: in an earlier report, significant differences [such as a highly elevated ratio of cholesteryl esters (CE) to wax esters (WE) in the Asian population compared with the Caucasian one] were reported. However, in our pilot experiments no such effect was observed. The goal of this study was to compare samples of meibum collected from male and female donors of both races, and evaluate in detail possible limits of natural variability of the chemical composition of their meibum.
Human subjects first underwent standard ocular evaluation in ophthalmic clinic settings. Meibum specimens were expressed from MG of normal (non-DE) donors and analyzed by liquid chromatography–mass spectrometry as described earlier. Several lipid classes, such as WE, free cholesterol (Chl), CE, O-acylated ω-hydroxy fatty acids and their Chl-esters, free fatty acids (FFA), and triacyl glycerols (TAG) were evaluated. Lipids were analyzed as intact species.
Repetitive analyses of the same samples and lipid standards produced standard deviations (SD) of 5±2% of the corresponding means for major representatives of each class of lipids, and up to 30% – for minor ones. Differences in study samples that exceeded these values were deemed to be related to the differences between the study groups. However, the effects of race and sex on HM were found to be rather small, and mostly affected relatively minor lipids, such as Chl, FFA, and TAG. The major lipids differed by less than ±15%, on average. The CE/WE ratio was identical in two races. Random changes within individual groups of lipids were observed, such as a trend toward accumulation of shorter chain CE in females. However, these changes seemingly produced no obvious patterns and could not be systematized at this time.
MG in non-DE humans is a tightly controlled biosynthetic environment that produces a secretion with a rather conserved composition regardless of sex and race (Asian or Caucasian).
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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