Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
Elife. 2020 Apr 7;9:e53582. doi: 10.7554/eLife.53582.
Meibum lipids form a lipid layer on the outermost side of the tear film and function to prevent water evaporation and reduce surface tension. (-Acyl)-ω-hydroxy fatty acids (OAHFAs), a subclass of these lipids, are thought to be involved in connecting the lipid and aqueous layers in tears, although their actual function and synthesis pathway have to date remained unclear. Here, we reveal that the fatty acid ω-hydroxylase is involved in OAHFA production. -deficient mice exhibited damaged corneal epithelium and shortening of tear film break-up time, both indicative of dry eye disease. In addition, tears accumulated on the lower eyelid side, indicating increased tear surface tension. In -deficient mice, the production of wax diesters (type 1ω and 2ω) and cholesteryl OAHFAs was also impaired. These OAHFA derivatives show intermediate polarity among meibum lipids, suggesting that OAHFAs and their derivatives contribute to lipid polarity gradient formation for tear film stabilization.
睑脂在泪膜的最外侧形成一层脂质，起到防止水分蒸发和降低表面张力的作用。这些脂质中的一种亚类是（酰基）-ω-羟基脂肪酸（OAHFAs），据认为其参与连接泪液中的脂质层和水相层，尽管其实际功能和合成途径迄今仍不清楚。在这里，我们揭示了脂肪酸ω-羟化酶参与 OAHFA 的生成。-/- 小鼠表现出角膜上皮损伤和泪膜破裂时间缩短，这两者均表明患有干眼症。此外，在下眼睑侧堆积了眼泪，表明泪液表面张力增加。在 -/- 小鼠中，蜡二酯（1ω 和 2ω 型）和胆甾醇 OAHFA 的产生也受到损害。这些 OAHFA 衍生物在睑脂中具有中等极性，表明 OAHFAs 及其衍生物有助于形成泪膜稳定的脂质极性梯度。
