A Solute Gradient in the Tear Meniscus. I. A Hypothesis to Explain Marx's Line
A Solute Gradient in the Tear Meniscus. I. A Hypothesis to Explain Marx's Line
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DOI：
10.1016/s1542-0124(11)70014-3
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发表时间：
2011-04-01
期刊：
影响因子：
6.4
通讯作者：
Tiffany, John M.
中科院分区：
文献类型：
--
作者：
Bron, Anthony J.;Yokoi, Norihiko;Tiffany, John M.
马克思线是粘膜-皮肤交界处后面的粘膜染色线。通过丽丝胺绿和相关染料的染色，它可以在所有正常的眼睑中表现出来。在所有的身体孔中，只有眼睛和嘴巴的粘膜直接暴露在大气中。在本文中，我们认为，对于眼睛来说，这种暴露导致了马克思路线的形成。撕裂半月板向其顶端逐渐变薄，在那里它被固定在眼睑的粘膜皮肤连接处。它也向黑线方向变薄，这条黑线在眨眼后将半月板与泪膜分开。我们预测，由于撕裂半月板的几何形状，蒸发在前后平面的半月板剖面上产生一个溶质梯度，该梯度在半月板顶端达到峰值。结果之一是扩大这些部位的泪液摩尔浓度水平，使它们达到高渗透压的比例。初步的数学模型表明，由于空间限制、该部位存在撕裂和表面粘蛋白以及有限的流体流动，溶质从半月板顶点向粘膜皮肤连接处的平流和扩散对这种效应的稀释将受到限制。我们的结论是，从撕裂半月板蒸发水分的损失可能导致一个生理区域的高渗透性和相关的压力，咬合结膜，直接后面的粘膜皮肤连接处。我们假设这刺激了该部位的高上皮细胞更新，上皮不完全成熟，以及关键分子如MUC 16和半乳糖凝集素-3的表达失败，这些分子与表面上皮细胞之间的紧密连接对于封闭眼表面和防止染料和其他分子渗透到上皮中是必要的。这是作为马克思路线的基础提出的。在本文的第二部分（也发表在本期的The Ocular Surface）中，我们讨论了影响眼睑边缘的这种机制的其他病理生理后果。
Marx's line is a line of mucosal staining behind the mucocutaneous junction. It can be demonstrated throughout life in all normal lids by staining with lissamine green and related dyes. Of all the body orifices, only the mucosae of the eye and mouth are directly exposed to the atmosphere. In this paper, we suggest that for the eye, this exposure leads to the formation of Marx's line. The tear meniscus thins progressively toward its apex, where it is pinned at the mucocutaneous junction of the lid. It also thins toward the black line, which segregates the meniscus from the tear film after the blink. We predict that, because of the geometry of the tear meniscus, evaporation generates a solute gradient across the meniscus profile in the anteroposterior plane, which peaks at the meniscus apices at the end of the interblink. One outcome would be to amplify the level of tear molarity at these sites so that they reach hyperosmolar proportions. Preliminary mathematical modeling suggests that dilution of this effect by advection and diffusion of solute away from the meniscus apex at the mucocutaneous junction will be restricted by spatial constraints, the presence of tear and surface mucins at this site, and limited fluid flow. We conclude that evaporative water loss from the tear meniscus may result in a physiological zone of hyperosmolar and related stresses to the occlusal conjunctiva, directly behind the mucocutaneous junction. We hypothesize that this stimulates a high epithelial cell turnover at this site, incomplete epithelial maturation, and a failure to express key molecules such as MUC 16 and galectin-3, which, with the tight junctions between surface epithelial cells, are necessary to seal the ocular surface and prevent penetration of dyes and other molecules into the epithelium. This is proposed as the basis for Marx's line. In Part II of this paper (also published in this issue of The Ocular Surface), we address additional pathophysiological consequences of this mechanism, affecting lid margins.