The Role of Selectin-Mediated Recognition in Glaucoma

描述(申请人提供)：青光眼是世界上仅次于白内障的第二大致盲原因，约有7000万人受到影响。房水流出通道阻塞引起的眼压升高是原发性开角型青光眼发生的主要危险因素。由于缺乏对流出设施抵抗的分子机制的了解，这种致盲疾病的治疗受到了影响。在最近的一项研究中，糖类结合蛋白E-选择素(ELAM-1，CD62E)被确定为青光眼的特异性分子标志物。结果表明，在不同病因青光眼的流出通道中，E-选择素持续存在于小梁网(TM)细胞上，而在所有正常眼的流出通道中均无E-选择素的表达。我们提出了一个独特的假设，即TM细胞表面的E-选择素通过与相邻细胞或房水中假定的糖蛋白受体结合，激活关键的信号通路，进而通过促进细胞-基质和/或细胞-细胞之间的相互作用和细胞骨架的变化，提供针对眼部房水流出途径的保护性应激反应。在NEI R03的这一应用中，我们建议进行试点研究，以确定该假设是否值得详细调查。在目标1中，利用免疫组织化学和Western印迹分析，我们将确定在正常和青光眼患者的TM细胞和房水中表达选择素的特定碳水化合物配体(如果有的话)。在目标2中，我们将确定选择素/碳水化合物介导的信号在体外是否促进TM细胞与各种细胞外基质分子的黏附。拟议的研究将确定基于选择素的碳水化合物识别系统是否在青光眼房水流出阻力的发病机制中发挥作用。

DESCRIPTION (provided by applicant): Glaucoma is the second leading cause of blindness in the world after cataract, affecting approximately 70 million people. Elevated intraocular pressure due to the obstruction of the aqueous outflow pathway is a major causal risk factor in the development of primary open-angle glaucoma. Treatment of this blinding disease is compromised because of the lack of understanding of the molecular mechanism responsible for the resistance to the outflow facility. In a recent study, a carbohydrate-binding protein, E-selectin (ELAM-1, CD62E), was identified as a specific molecular marker of glaucoma. It was demonstrated that while E-selectin is consistently present on trabecular meshwork (TM) cells in the outflow pathways of eyes of glaucomas of diverse etiology, it was absent in the outflow pathway of all normal eyes examined. We propose a unique hypothesis that TM cell surface E-selectin, by binding to its putative glycoprotein counterreceptors on adjacent cells or in aqueous humor activates key signaling pathways, which in turn, by promoting cell-matrix and/or cell-to-cell interactions and cytoskeletal changes, provide a protective stress response specific to the aqueous outflow pathway of the eye. In this NEI R03 application, we propose pilot studies to determine whether the hypothesis merits a detailed investigation. In Aim 1, using immunohistochemical and Western blot analysis, we shall establish which specific carbohydrate ligands of selectins, if any, are expressed on the TM cells and in the aqueous humor of normal and glaucomatous eyes. In Aim 2, we shall determine whether the selectins/carbohydrate-mediated signaling promotes adhesion of TM cells to a variety of extracellular matrix molecules in vitro. The proposed studies will determine whether the selectin-based carbohydrate recognition system plays a role in the pathogenic mechanisms of aqueous outflow resistance in glaucoma.