The Effect of Ambient Ozone on Unsaturated Tear Film Wax Esters

Paananen, Riku O.; Rantamäki, Antti H.; Parshintsev, Jevgeni; Holopainen, Juha M.

doi:10.1167/iovs.15-18398

Cited by 16 publications

(11 citation statements)

References 53 publications

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“…In a recent study evaluating the effects of exposure to ozone on the lipid component of tear film, the authors reported no signs of ozonolysis products in the tear fluid; this finding was most attributable to the antioxidant mechanisms in tear fluid and detoxification enzymes present in the cornea. [39,40]…”

Section: Discussionmentioning

confidence: 99%

Effects of Exposure to Ozone on the Ocular Surface in an Experimental Model of Allergic Conjunctivitis

Lee

Kim

et al. 2017

PLoS ONE

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Based on previous findings that ozone can induce an inflammatory response in the ocular surface of an animal model and in cultured human conjunctival epithelial cells, we investigated whether exposure to ozone exacerbates symptoms of allergic conjunctivitis. We evaluated the effects of exposure to ozone on conjunctival chemosis, conjunctival injection, corneal and conjunctival fluorescein staining scores, production of inflammatory cytokines in tears, and aqueous tear production in a mouse model of allergic conjunctivitis. To validate our in vivo results, we used interleukin (IL)-1α-pretreated conjunctival epithelial cells as an in vitro substitute for the mouse model. We evaluated whether exposure to ozone increased the inflammatory response and altered oxidative status and mitochondrial function in IL-1α-pretreated conjunctival epithelial cells. In the in vivo study, ozone induced increases in conjunctival chemosis, conjunctival injection, corneal and conjunctival fluorescein staining scores, and production of inflammatory cytokines, accompanied by a decrease in tear volume. In the in vitro study, exposure to ozone led to additional increases in IL-6 and tumor necrosis factor-α mRNA levels, which were already induced by treatment with IL-1α. Ozone did not induce any changes in cell viability. Pretreatment with IL-1α increased the expression of manganese superoxide dismutase, and exposure to ozone led to additional increments in the expression of this antioxidant enzyme. Ozone did not induce any changes in mitochondrial activity or expression of mitochondrial enzymes and proteins related to mitochondrial function, with the exception of phosphor-mammalian target of rapamycin. Treatment with butylated hydroxyanisole, a free radical scavenger, attenuated the ozone-induced increases in IL-6 expression in IL-1α-pretreated conjunctival epithelial cells. Therefore, we conclude that exposure to ozone exacerbates the detrimental effects on the integrity of the ocular surface caused by conjunctival allergic reactions, and further increases the inflammatory response in IL-1α-pretreated conjunctival epithelial cells.

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Section: Discussionmentioning

confidence: 99%

Effects of Exposure to Ozone on the Ocular Surface in an Experimental Model of Allergic Conjunctivitis

Lee

Kim

et al. 2017

PLoS ONE

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“…As shown recently, the surprisingly high (apparent) surface activity of meibum, 23 wax esters, 15,23 and OAHFAs 23 is very likely due to the rapid ozonolysis 19 of such lipids at the air-water interface. As expected based on their structure, such lipids show miniscule surface activity when the degradation of the lipids is prevented.…”

Section: Discussionmentioning

confidence: 68%

“…1). In contrast, when the ozonolysis of the lipids is not prevented, WEs degrade gradually into surfaceactive compounds 19 and show high surface activity. 15 Based on our preliminary studies, the same applies to CO (data not shown).…”

Section: Discussionmentioning

confidence: 99%

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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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“…An acrylic cover was put over the trough to protect the surface from dust and to suppress subphase evaporation. This enclosure was supplied with air passed through an Ozone Solutions ODS-3P ozone destruct unit (Hull, Iowa, USA) in order to prevent ozone-induced oxidation of the films (Paananen et al 2015). After 15 min, to allow chloroform evaporation, film area compression was started using two symmetrically moving barriers.…”

Section: Langmuir Surface Balance Experimentsmentioning

confidence: 99%

Surface properties and exponential stress relaxations of mammalian meibum films

et al. 2016

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The surface properties of meibomian secretion (MGS), the major constituent of the tear film (TF) lipid layer, are of key importance for TF stability. The interfacial properties of canine, cMGS, and feline, fMGS, meibum films were studied using a Langmuir surface balance. These species were selected because they have blinking frequency and TF stability similar to those of humans. The sample's performance during dynamic area changes was evaluated by surface pressure (π)-area (A) isocycles and the layer structure was monitored with Brewster angle microscopy. The films' dilatational rheology was probed via the stress-relaxation technique. The animal MGS showed similar behavior both between each other and with human MGS (studied previously). They form reversible, non-collapsible, multilayer thick films. The relaxations of canine, feline, and human MGS films were well described by double exponential decay reflecting the presence of two processes: (1) fast elastic process, with characteristic time τ < 10 s and (2) slow viscous process, with τ > 100 s-emphasizing the meibum layers viscoelasticity. The temperature decrease from 35 to 25 °C resulted in decreased thickness and lateral expansion of all MGS layers accompanied with increase of the π/A hysteresis and of the elastic process contribution to π relaxation transients. Thus, MGS films of mammals with similar blinking frequency and TF stability have similar surface properties and stress relaxations unaltered by the interspecies MGS compositional variations. Such knowledge may impact the selection of animal mimics of human MGS and on a better understanding of lipid classes' impact on meibum functionality.

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The Effect of Ambient Ozone on Unsaturated Tear Film Wax Esters

Cited by 16 publications

References 53 publications

Effects of Exposure to Ozone on the Ocular Surface in an Experimental Model of Allergic Conjunctivitis

Effects of Exposure to Ozone on the Ocular Surface in an Experimental Model of Allergic Conjunctivitis

The Effect of Phospholipids on Tear Film Lipid Layer Surface Activity

Surface properties and exponential stress relaxations of mammalian meibum films

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