title: Meibum lipid composition in Asians with dry eye disease.
abstract: BACKGROUND
  Previous 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.
  
  
  RESULTS
  We 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.
  
  
  CONCLUSIONS
  The 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.
authors: Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
authors: Sin Man
authors: SM
authors: Lam
authors: Louis
authors: L
authors: Tong
authors: Siew Sian
authors: SS
authors: Yong
authors: Bowen
authors: B
authors: Li
authors: Shyam S
authors: SS
authors: Chaurasia
authors: Guanghou
authors: G
authors: Shui
authors: Markus R
authors: MR
authors: Wenk
mesh_terms: D000328:Adult; D000368:Aged; D001208:Asia / Q000453:epidemiology; D016022:Case-Control Studies; D018450:Disease Progression; D015352:Dry Eye Syndromes / Q000453:epidemiology / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D050356:Lipid Metabolism; D008055:Lipids / Q000032:analysis*; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D008537:Meibomian Glands / Q000737:chemistry*; D008875:Middle Aged; D010715:Phosphatidylglycerols; D015995:Prevalence; D014280:Triglycerides
chemical_list: D008055:Lipids; D010715:Phosphatidylglycerols; D014280:Triglycerides