Cellular Biology of the Trabecular Meshwork

描述：我们研究的长期目标是了解控制正常眼睛水流出阻力的解剖和生化因素，以及青光眼发生的病理生理变化。我们的总体假设是：在正常的眼睛中，施莱姆氏管细胞下的细胞外基质（ECM）产生了大部分的水流出阻力，通过与ECM的相互作用，管细胞贡献了大约22%的阻力。这个比例在POAG中是未知的。基于我们已完成的研究结果，由此产生了三个假设，并将在我们当前的提案中进行测试：1)尽管ECM主要负责水流出阻力，但ECM是由小梁细胞形成的，流出阻力最终是一个“细胞”过程。小梁细胞可以对刺激作出反应并改变其合成轮廓。将研究两个临床结果。这两项发现都涉及到在其他组织中诱导细胞变化的分子。它们是测试TM细胞是否以同样的方式反应，以及TM细胞的变化是否会影响IOP的原型：(1)POAG眼的水中tgf - β 2增加。我们认为这是POAG发生的根本机制。它引起培养人眼的IOP升高，可能是长期寻找的POAG发病机制的模型（aim 1）。(2)前列腺素治疗在临床上和培养眼中都降低了IOP。前列腺素降低IOP的机制仍然存在争议：尽管所有的研究都认为它增加了巩膜流出，但它们对TM的影响却存在分歧。我们认为PG影响小梁细胞降低IOP（目的2）。2)POAG中ECM的小幅增加表明不存在“解剖性堵塞”。相反，POAG是一种生理过程的紊乱，最好通过与正常眼睛的比较来发现。生化和结构证据都将检验这一假设。心肌素存在于水中，可提高培养眼的IOP。正常眼睛和POAG的水样水平是未知的。如果在POAG中升高，这将在显微镜下被遗漏：不被视为“解剖堵塞”（目的3）。青光眼患者眼管细胞的细胞特性发生变化（“变硬”或更多粘附细胞抵抗水流出），可使IOP升高，但在显微镜下无法观察到。去除POAG中的施莱姆氏管细胞应该确定它们对流出阻力的贡献（目标4）。3)TM中施莱姆氏管细胞不在ECM上的区域（“扩展的JCT结构”）由于管道细胞-ECM相互作用的丧失，流出阻力较小。这种扩展的JCT结构与经典的大腔施勒姆管有很大的不同。这些区域将是“优先流动”区域，水性示踪剂应首先出现在这些区域。如果发生这种情况，它将改变我们对水如何通过TM的基本理解（目标5）。

DESCRIPTION: The long term goal of our research is to understand the anatomic and biochemical factors that control aqueous outflow resistance in the normal eye, and the pathophysiologic changes that occur in the glaucomatous eye. Our overall hypothesis: In the normal eye, the extracellular matrix (ECM) underlying the cells of Schlemm's canal creates the majority of aqueous outflow resistance, with the canal cells contributing about 22% of the resistance through their interaction with the ECM. This ratio is unknown in POAG. Three hypothesis arise from this, based upon findings from our completed grant, and will be tested in our current proposal: 1) Although the ECM is primarily responsible for aqueous outflow resistance, the ECM is made by trabecular cells, and outflow resistance is ultimately a "cellular" process. Trabecular cells can respond to stimuli and change their synthetic profile. Two clinical findings will be studied. Both findings involve molecules that induce cellular changes in other tissues. They are prototypes to test if TM cells respond in the same way, and if TM cell changes can affect IOP: (1) TGF-beta2 is increased in the aqueous of POAG eyes. We believe it is the fundamental mechanism for the development of POAG. It causes increased IOP in cultured human eyes, and may be the long-sought model for the pathogenesis of POAG (aim 1). (2) Prostaglandin treatment decreases IOP clinically, and also in cultured eyes. The mechanism of prostaglandins in lowering IOP remains contested: although all studies agree it increases uveoscleral outflow, they disagree on its effect on the TM. We believe PG affect trabecular cells to decrease IOP (aim 2). 2) The small increase of ECM in POAG indicates an "anatomic plug" is not present. Instead, POAG is a derangement of a physiologic process, best found by comparisons with normal eyes. Both biochemical and structural evidence will test this hypothesis. Myocilin is present in aqueous, and can increase IOP in cultured eyes. Aqueous levels in normal eyes and POAG are unknown. If elevated in POAG, this would be missed by microscopy: not seen as an "anatomic plug" (aim 3). A change in the cellular properties of the canal cells in glaucoma ("stiffer" or more adherent cells that resist aqueous outflow) could elevate IOP but would not be seen by microscopy. Removal of Schlemm's canal cells in POAG should determine their contribution to outflow resistance (aim 4). 3) Regions of the TM where Schlemm's canal cells do not sit on ECM ("expanded JCT configuration") have less outflow resistance due to loss of the canal cell-ECM interaction. This expanded JCT configuration differs significantly from the classic large lumen Schlemm's canal. These regions will be "preferential flow" regions, and aqueous tracers should appear in these regions first. If this occurs, it would change our basic understanding of how aqueous passes through the TM (aim 5).