Cellular Biology of the Trabecular Meshwork

产品说明：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学和生物化学因素，以及发生在青光眼眼的病理生理变化。我们的总体假设：在正常眼中，施累姆氏管细胞下面的细胞外基质（ECM）产生大部分的房水流出阻力，其中管细胞通过其与ECM的相互作用贡献约22%的阻力。该比例在POAG中未知。基于我们已完成的资助的发现，由此产生了三个假设，并将在我们目前的提案中进行测试：1）尽管ECM主要负责水流出阻力，但ECM由小梁细胞制成，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特征。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细胞是否以相同的方式响应的原型，以及TM细胞的变化是否可以影响IOP：（1）TGF-β 2在POAG眼的房水中增加。我们认为这是POAG发展的基本机制。它在培养的人眼中引起IOP增加，并且可能是POAG发病机制的长期寻求的模型（目的1）。(2)前列腺素治疗在临床上降低IOP，并且在培养的眼睛中也降低IOP。降眼压的机制仍有争议：尽管所有研究都认为它会增加葡萄膜巩膜流出，但它们对TM的影响不一致。我们认为PG影响小梁细胞以降低IOP（目的2）。2)POAG中ECM的少量增加表明不存在“解剖学栓塞”。相反，POAG是一种生理过程的紊乱，最好通过与正常眼睛进行比较来发现。生物化学和结构证据都将检验这一假设。Myocilin存在于房水中，并且可以增加培养眼的IOP。正常眼和POAG的房水水平尚不清楚。如果在POAG中升高，则显微镜检查会遗漏：未观察到“解剖学栓塞”（目的3）。青光眼中的管细胞的细胞特性的变化（“更硬”或更多的粘附细胞，抵抗房水流出）可能会升高IOP，但不会被显微镜观察到。在POAG中去除Schlemm管细胞应确定其对流出阻力的贡献（目的4）。3)其中施莱姆氏管细胞不位于ECM上的TM区域（“扩展的JCT配置”）由于管细胞-ECM相互作用的损失而具有较小的流出阻力。这种扩张的JCT结构与经典的大腔Schlemm管明显不同。这些区域将是“优先流”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).