The Presence and Significance of Polar Meibum and Tear Lipids

Pucker, Andrew D.; Haworth, Kristina M.

doi:10.1016/j.jtos.2014.06.002

Cited by 65 publications

(42 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Their findings, summarized in several recent reviews [(Green-Church et al, 2011), (Butovich, 2011a), (Pucker and Haworth, 2015), (Butovich, 2013), (Butovich, 2009c), and references cited therein], demonstrated that meibum is mostly comprised of neutral lipids, such as wax esters (WE), cholesteryl esters (CE), free cholesterol (Chl), and triacylglycerols (TAG), and smaller amounts of more polar compounds, such as free fatty acids (FFA), phospholipids (PL), sphingomyelins (SM), ceramides (Cer), and others. Most of the meibomian lipids are complex, featuring at least one or more ester bonds.…”

Section: Lipids Of Meibummentioning

confidence: 99%

“…Meibum and aqueous tears mix during the blink to form the tear film. Currently, the predominant view is that the tear film is a rather stratified structure, the upper sublayer of which is formed mostly of meibum, and, possibly, smaller amounts of polar and nonpolar lipids of other origins (Butovich, 2008) (Butovich, 2013) (Pucker and Haworth, 2015), while the inner part that faces the ocular surface epithelium, is aqueous (Fig. 2) (Green-Church et al, 2011) (Butovich, 2011a).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Meibomian glands, meibum, and meibogenesis

Butovich

2017

Experimental Eye Research

105

118

View full text Add to dashboard Cite

Meibum is a lipid-rich secretion that is produced by fully differentiated meibocytes in the holocrine Meibomian glands (MG) of humans and most mammals. The secretion is a part of a defense mechanism that protects the ocular surface from hazardous environmental factors, and from desiccation. Meibomian lipids that have been identified in meibum are very diverse and unique in nature. The lipid composition of meibum is different from virtually any other lipid pool found in the human body. In fact, meibum is quite different from sebum, which is the closest secretion that is produced by anatomically, physiologically, and biochemically related sebaceous glands. However, meibum of mice have been shown to closely resemble that of humans, implying similar biosynthetic mechanisms in MG of both species. By analyzing available genomic, immunohistochemical, and lipidomic data, we have envisioned a unifying network of enzymatic reactions that are responsible for biosynthesis of meibum, which we call meibogenesis. Our current theory is based on an assumption that most of the biosynthetic reactions of meibogenesis are catalyzed by known enzymes. However, the main features that make meibum unique – the ratio of identified classes of lipids, the extreme length of its components, extensive ω-hydroxylation of fatty acids and alcohols, iso- and anteiso-branching of meibomian lipids (e.g. waxes), and the presence of rather unique complex lipids with several ester bonds – make it possible that either the activity of known enzymes is altered in MG, or some unknown enzymes contribute to the processes of meibogenesis, or both. Studies are in progress to elucidate meibogenesis on molecular level.

show abstract

Section: Lipids Of Meibummentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Meibomian glands, meibum, and meibogenesis

Butovich

2017

Experimental Eye Research

105

118

View full text Add to dashboard Cite

show abstract

“…Lipids supplied principally by the meibomian glands provide the tear film lipid layer (TFLL), a complex mixture of lipids that create a thin hydrophobic film that serves to protect the tear film from evaporation. The physical properties of the tear film such as its stability and spreading are greatly influenced by the molecular lipid composition of the TFLL [3][4][5][6] . Deviations in the composition of the TFLL are likely to modulate the physical properties of the tear film and in turn effect a change in evaporation of the aqueous tear 7 .…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

View full text Add to dashboard Cite

Mitchell, T. W. (2016). Intersubject and interday variability in human tear and meibum lipidomes: a pilot study. The Ocular Surface, 14 (1), 43-48. Intersubject and interday variability in human tear and meibum lipidomes: a pilot study Abstract Purpose Our aim was to quantitate day-to-day changes in the tear and meibum lipid profile of individual subjects in a pilot study of healthy humans. Methods Matched tear and meibum samples were obtained from four subjects on three consecutive days. Quantitative lipid profiles of human basal tears and meibum were compared using multivariate analysis by principal components. Results Substantial differences in the lipid profile between subjects were observed, while lipid profiles were steady across the three consecutive days of sampling. Multivariate principal component analysis demonstrated that lysophosphatidylcholine was the largest variant lipid class between subjects in tears, while wax esters comprised the most variation between subjects in meibum secretions. Conclusion Interday variability is shown to be much smaller than interpatient variability, suggesting that tears and meibum subjects both have unique profiles in humans. Disciplines Medicine and Health Sciences Publication DetailsBrown, S. H. J., Kunnen, C. M. E., Papas, E. B., Lazon de la Jara, P., Willcox, M. D. P., Blanksby, S. 2 ABSTRACT Purpose: Our aim was to quantitate day-to-day changes in the tear and meibum lipid profile of individual subjects in a pilot study of healthy humans.Methods: Matched tear and meibum samples were obtained from four subjects on three consecutive days. Quantitative lipid profiles of human basal tears and meibum were compared using multivariate analysis by principal components.Results: Substantial differences in the lipid profile between subjects were observed, while lipid profiles were steady across the three consecutive days of sampling.Multivariate principal component analysis demonstrated that lysophosphatidylcholine was the largest variant lipid class between subjects in tears, while wax ester contributed the most to variation between subjects in meibum secretions.Conclusion: Inter-day variability is shown to be much smaller that inter-patient variability, suggesting that both tears and meibum subjects have unique profiles in individuals.

show abstract

“…10 Despite their small proportion relative to nonpolar lipids, PLs seem to have an essential impact on the function of the TFLL and, consequently, on the health of the ocular surface. 11 Cholesteryl esters and WEs are classified as nonpolar since they lack the large highly hydrophilic head group of polar lipids. Polar lipids in aqueous environment orient in such fashion that the contact of water with the hydrophobic parts of the molecule, the acyl chains, is minimized, whereas the head group remains in contact with water.…”

mentioning

confidence: 99%

The Effect of Phospholipids on Tear Film Lipid Layer Surface Activity

Rantamäki

Holopainen

2017

Invest. Ophthalmol. Vis. Sci.

View full text Add to dashboard Cite

Citation: Rantamäki AH, Holopainen JM. The effect of phospholipids on tear film lipid layer surface activity. Invest Ophthalmol Vis Sci. 2017;58:149-154. DOI:10.1167/ iovs.16-20468 PURPOSE. We illustrate the importance of small quantities (<10 mol%) of polar phospholipids on the surface-active behavior of meibum-like lipid compositions.METHODS. Artificial meibum-like lipid mixture containing cholesteryl and wax esters was mixed with differing amounts of phosphatidylcholine (PC). The surface activity of these mixtures was investigated at the air-water interface by recording surface pressure created by the lipid layer as a function of molecular area at 378C. The PC proportion in the mixtures was 0, 2.5, 5, 7.5, or 10 mol%, and the remaining proportion in the mixture was 50:50 (mol/mol) of cholesteryl oleate (CO) and behenyl oleate (BO). Also, the effect of temperature was investigated.RESULTS. The surface activity of the mixtures increased in a very predictable and consistent fashion as a function of the PC proportion. The lipid mixture containing only CO and BO showed miniscule surface activity. However, already 2.5% PC mixed with the nonpolar CO and BO generated considerable increase in surface pressure. At small surface areas, the behavior of 7.5% and 10% PC compositions started to approach that of a pure PC monolayer. The temperature did not have a considerable impact on the surface-active behavior of the PCcontaining compositions.CONCLUSIONS. The polar phospholipids have a considerable effect on the surface-active properties of artificial tear film lipid layer (TFLL) compositions. Surprisingly, this takes place already at very low and physiologically relevant PC proportions. The effect is more dependent on the actual amount of the phospholipids at the air-tear interface than on the relative amount of these lipids in TFLL.

show abstract

The Presence and Significance of Polar Meibum and Tear Lipids

Cited by 65 publications

References 64 publications

Meibomian glands, meibum, and meibogenesis

Meibomian glands, meibum, and meibogenesis

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

The Effect of Phospholipids on Tear Film Lipid Layer Surface Activity

Contact Info

Product

Resources

About