Schepens Eye Research Institute/Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA.
Exp Eye Res. 2013 Dec;117:62-78. doi: 10.1016/j.exer.2013.07.027. Epub 2013 Aug 14.
The ocular surface including the cornea and conjunctiva and its overlying tear film are the first tissues of the eye to interact with the external environment. The tear film is complex containing multiple layers secreted by different glands and tissues. Each layer contains specific molecules and proteins that not only maintain the health of the cells on the ocular surface by providing nourishment and removal of waste products but also protect these cells from environment. A major protective mechanism that the corneal and conjunctival cells have developed is secretion of the innermost layer of the tear film, the mucous layer. Both the cornea and conjunctiva express membrane spanning mucins, whereas the conjunctiva also produces soluble mucins. The mucins present in the tear film serve to maintain the hydration of the ocular surface and to provide lubrication and anti-adhesive properties between the cells of the ocular surface and conjunctiva during the blink. A third function is to contribute to the epithelial barrier to prevent pathogens from binding to the ocular surface. This review will focus on the different types of mucins produced by the corneal and conjunctival epithelia. Also included in this review will be a presentation of the structure of mucins, regulation of mucin production, role of mucins in ocular surface diseases, and the differences in mucin production by the ocular surface, airways and gastrointestinal tract.
眼表包括角膜和结膜及其表面的泪膜，是眼睛与外界环境最先接触的组织。泪膜是一种复杂的结构，包含由不同腺体和组织分泌的多个层次。每个层次都含有特定的分子和蛋白质，不仅通过提供营养和清除废物来维持眼表细胞的健康，还保护这些细胞免受环境侵害。角膜和结膜细胞发展出的主要保护机制是分泌泪膜的最内层，即黏液层。角膜和结膜都表达跨膜粘蛋白，而结膜也产生可溶性粘蛋白。泪膜中的粘蛋白有助于保持眼表的湿润，并在眨眼时提供眼表和结膜细胞之间的润滑和抗粘连特性。第三个功能是有助于上皮屏障，防止病原体与眼表结合。这篇综述将重点介绍角膜和结膜上皮产生的不同类型的粘蛋白。本文还将介绍粘蛋白的结构、粘蛋白产生的调节、粘蛋白在眼表疾病中的作用以及眼表、气道和胃肠道粘蛋白产生的差异。
