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房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：在正常眼中，Schlemm管细胞下的细胞外基质(ECM)产生了大部分房水流出阻力，其中管内细胞通过与ECM的相互作用贡献了约22%的阻力。这一比例在POAG中是未知的。根据我们完成的资助结果，由此产生了三个假说，并将在我们目前的提案中得到验证：1)虽然细胞外基质主要负责房水流出阻力，但细胞外基质是由小梁细胞产生的，流出阻力最终是一个“细胞”过程。小梁细胞可以对刺激做出反应，并改变其合成轮廓。两个临床发现将被研究。这两项发现都涉及在其他组织中引发细胞变化的分子。它们是用来测试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眼压的原型：(1)POAG眼房水中的转化生长因子-β2增加。我们认为，这是POAG发展的根本机制。它导致培养的人眼眼压升高，并可能成为POAG发病机制的长期寻求的模型(目标1)。(2)前列腺素治疗在临床上降低了眼压，在培养眼中也是如此。前列腺素降低眼压的机制仍然存在争议：尽管所有研究都认为它增加了葡萄膜巩膜流出量，但对其对TM的影响存在分歧。我们认为PG通过影响小梁细胞来降低眼压(目标2)。(2)POAG患者ECM小幅增加，提示不存在“解剖栓”。相反，POAG是一种生理过程的错乱，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。霉菌素存在于房水中，会增加培养眼的眼压。正常眼和开角型青光眼的房水水平尚不清楚。如果在POAG中升高，显微镜会忽略这一点：不被视为“解剖塞”(Aim 3)。青光眼患者眼管细胞特性的改变(抵抗房水流出的更硬的或更多的贴壁细胞)可能会升高眼压，但在显微镜下是看不到的。去除POAG中的Schlemm管细胞应确定它们对流出阻力的贡献(目标4)。3)TM中Schlemm管细胞不在ECM上的区域(“扩展JCT构型”)由于失去了通道细胞与ECM的相互作用而具有较小的流出阻力。这种扩大的JCT结构与经典的大管腔Schlemm管有很大的不同。这些区域将是“优先流动”区域，水相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).