Pressure Regulation of Human Trabecular Meshwork Genes

描述（申请人提供）：青光眼是一种导致不可逆失明的视神经病变。我们研究青光眼的方法包括选择与该疾病相关的临床条件，并在分子水平上研究临床参数。眼压升高是青光眼发生的主要危险因素。在人类中，90%的房水通过小梁网（TM）排出眼睛。因此，功能失调的TM会导致阻力增加和IOP升高。由于组织的生理机能受其基因表达的支配，在之前的资助周期中，我们在IOP升高的条件下检查了TM的差异表达。在分析了许多比较正常和高IOP灌注的死后人眼的芯片阵列后，我们揭示了一些参与钙化过程的基因。我们进一步发现，这些过程不仅存在于TM中，而且在青光眼患者的TM中似乎更活跃。基于这些发现，我们假设TM钙化与IOP和流出设施的调节有关。骨和血管组织中控制生理和病理钙化的基因和机制在TM中是活跃的，这些过程以及抑制它们的努力是控制房水流出的调节系统的一部分。我们进一步假设，未能保持TM矿化将影响沉积的胶原和弹性蛋白交联，从而对ECM硬化产生有害后果。为了验证这些假设，我们建议通过三个新的途径进一步表征已确定的机制。第一项研究将通过使用转基因小鼠在体内研究这一现象。第二个将研究人体器官培养的过程。第三项研究将使用原代人TM细胞来确定两种途径（WNT和lox相关的弹性蛋白/胶原交联）在TM矿化中的作用。这两种途径分别与血管钙化和成骨细胞分化有关，并与影响TM功能的条件有关。随着这些假设的发展，所获得的结果将为调控流出阻力的机制提供新的认识，并可能导致青光眼的新治疗方法。

DESCRIPTION (provided by applicant): Glaucoma is an optic neuropathy which causes irreversible blindness. Our approach to study glaucoma consists of selecting a well-established clinical condition associated with the disease and investigating the clinical parameter at the molecular level. Elevated intraocular pressure (IOP) is the major risk factor for the development of glaucoma. In humans, 90% of the aqueous humor exits the eye through the trabecular meshwork (TM). Thus, a dysfunctional TM results in increased resistance and elevated IOP. Because the physiology of a tissue is governed by the expression of its genes, during the previous grant cycle we examined TM differential expression under conditions of elevated IOP. After analyzing many chip arrays comparing normal and high IOP perfuse post-mortem human eyes, we unraveled a number of genes involved in calcification processes. We further uncovered that such processes were not only present in the TM, but also that they seemed to be more active in TMs from glaucomatous patients. Based on these findings, we hypothesize that TM calcification is linked to regulation of IOP and outflow facility. That genes and mechanisms that govern physiological and pathological calcification in the bone and vascular tissues are active in the TM, and that these processes, as well as efforts to inhibit them, are part of the regulatory systems that control aqueous humor outflow. We further hypothesize that failure to maintain TM mineralization in check will affect deposited collagen and elastin cross-linking with deleterious consequences to ECM hardening. To test these hypotheses we propose to further characterize the identified mechanism through three new avenues. The first will investigate the phenomenon in vivo, through the use of transgenic mice. The second will investigate the process in human organ cultures. The third will use primary human TM cells to determine the involvement of two pathways (WNT and LOX-related elastin/collagen cross-linking) in TM mineralization. These two pathways have been independently associated with vascular calcification and osteoblastic differentiation and, with conditions affecting TM function. Results to be obtained with the development of these hypotheses will provide new understanding on the mechanisms regulating outflow resistance and would potentially lead to new treatments for glaucoma. PUBLIC HEALTH RELEVANCE: Glaucoma is the second leading cause of irreversible blindness and the most common cause among African- Americans. Currently, there is no cure for glaucoma. Elevated intraocular pressure (IOP) is the major risk factor for the developing of glaucoma. IOP is maintained by the resistance of the trabecular meshwork to the flow of aqueous humor. The goal of our project is to investigate the relevance of a previously undescribed process of mineralization occurring in the trabecular meshwork for the regulation of IOP. The trabecular meshwork needs to have in place molecular mechanisms that would maintain the physical properties of elasticity, tension and softness. Maintenance of the softness is of highest relevance to the trabecular meshwork's function. Pathological calcification occurs in soft tissues and has important clinical implications. Ectopic calcifications are well known to occur in cardiovascular diseases, atherosclerosis, arthritis, kidney disease and cancers. Vascular calcification decreases elasticity of the blood vessels and increases their brittleness, leading to increase risk of arterial rupture. In this project we aim to characterize this process in the eye of transgenic animals, human eyes from post-mortem donors and primary trabecular meshwork cells obtained from residual tissue after corneal transplants. We will aim to further study the role of inhibitors of calcification in the trabecular meshwork and ultimate open a new door for the development of new treatments for Glaucoma.