Adsorption of Human Tear Lipocalin to Human Meibomian Lipid Films

Millar, Thomas J.; Mudgil, Poonam; Butovich, Igor A.; Palaniappan, Chendur K.

doi:10.1167/iovs.08-2097

Cited by 59 publications

(56 citation statements)

References 27 publications

(45 reference statements)

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“…The present conceptual study clearly illustrates the potential effect of PLs without considering interactions between lipids and proteins. The function of PLs may be highly affected by lipid-binding proteins such as lipocalin, [24][25][26] and PL transfer protein. 27,28 However, more investigations need to be performed regarding the lipid-protein interactions before the impact of the proteins on TFLL behavior can be explained in more detail.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Phospholipids on Tear Film Lipid Layer Surface Activity

Rantamäki

Holopainen

2017

Invest. Ophthalmol. Vis. Sci.

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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.

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Section: Discussionmentioning

confidence: 99%

The Effect of Phospholipids on Tear Film Lipid Layer Surface Activity

Rantamäki

Holopainen

2017

Invest. Ophthalmol. Vis. Sci.

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“…This raises the possibility that hydrocarbon chain order could contribute to the delivery of meibum from the meibomian glands to the lid margins. Lipid-protein and lipidaqueous interactions may influence meibum structure and spreading on the surface of tears [40][41][42][43][44] . Assuming meibum finds its way to the aqueous tear film surface, if the lipid-lipid interactions are too strong, the lipid will aggregate and will not spread.…”

Section: What Causes Changes In Meibum Order and Phase Transition Temmentioning

confidence: 99%

Physical Changes in Human Meibum with Age as Measured by Infrared Spectroscopy

et al. 2010

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Both lipids and mucins contribute to the stability of the tear film and lipids may inhibit tears from evaporating. Younger people have lower lipid viscosity, higher lipid volume, and a lower rate of tear evaporation. Since age-related changes in human meibum composition and conformation have never been investigated, as a basis for the study of lipid-associated changes with meibomian gland dysfunction, we used the power of infrared spectroscopy to characterize hydrocarbon chain conformation and packing in meibum from humans without dry eye symptoms in relation to age and sex. Meibum from normal human donors ranging in age from 3 to 88 years was studied. Meibum phase transitions were quantified by fitting them to a 4-parameter 2-state sigmoidal equation. Human meibum order and phase transition temperatures decrease with age and this trend may be attributed to lipid compositional changes. If meibum has the same thermodynamic properties on the surface of the tears as it does on the lid margin, a decrease in lipid-lipid interaction strength with increasing age could decrease the stability of tears since lipid-lipid interactions on the tear surface must be broken for the tear film to break up. This study also serves as a foundation to examine meibum conformational differences in meibum from people with meibomian gland dysfunction.

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“…For the purpose we formed mixed pseudo-binary films of MGS and polar lipid, Egg Sphingomyelin (SM) or Dipalmitoylphosphatidylcholine (DPPC), at the air/water interface of Langmuir surface balance. Langmuir surface balance was already successfully employed in pioneer studies of the interactions between tear proteins and meibium [18][19][20][21][22][23]. SM and DPPC are chosen because they were used in previous studies as synthetic mimics of TF polar lipids [24,25].…”

Section: Introductionmentioning

confidence: 99%

Interactions of Meibomian gland secretion with polar lipids in Langmuir monolayers

Georgiev

Kutsarova

Jordanova

et al. 2010

Colloids and Surfaces B: Biointerfaces

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a b s t r a c tThe surface interactions of Meibomian gland secretion (MGS) with polar lipid (PL), Egg Sphingomyelin (SM) or Dipalmitoylphosphatidylcholine (DPPC), are studied in mixed pseudo-binary films formed at the air/water interface of Langmuir surface balance. The behavior of the mixed films during slow quasi-equilibrium compression and during fast dynamic compression-decompression is registered by measurements of surface pressure and surface potential, and by monitoring film morphology with Brewster Angle Microscopy (BAM). Quasi-equilibrium compression isotherms are used to calculate the excess Gibbs and Helmholtz energy of mixing between MGS and PLs and thus to evaluate the interactions between the lipid compounds at the interface. The effects of PLs on the mixed film's elastic moduli of area compressibility, morphology and capability to attain high surface pressures are also examined.PLs interact with MGS with different strength and in different manner: MGS-SM interaction is weak and might lead to interfacial disaggregation of the thick meibium domains when SM is in excess, while MGS-DPPC interaction is strong and results in the formation of thick lipid aggregates. Both PLs increase the mixed films reciprocal compressibility and capability to achieve higher surface pressures. The results demonstrate that in vitro studies of the surface interactions between MGS and PLs might be beneficial in the selection of PLs for artificial tear formulations and for examination on molecular scale of the possible role of PLs at the ocular surface.

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Adsorption of Human Tear Lipocalin to Human Meibomian Lipid Films

Cited by 59 publications

References 27 publications

The Effect of Phospholipids on Tear Film Lipid Layer Surface Activity

The Effect of Phospholipids on Tear Film Lipid Layer Surface Activity

Physical Changes in Human Meibum with Age as Measured by Infrared Spectroscopy

Interactions of Meibomian gland secretion with polar lipids in Langmuir monolayers

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