The Role of GDF-15 in Aqueous Humor Outflow and Glaucoma

项目摘要 眼内压（IOP）升高，由通过小梁的房水（AH）引流受损引起 网状结构（TM）被认为加速青光眼中的视神经萎缩和视网膜神经节细胞死亡 患者调节AH通过TM引流的外部因素和细胞内机制均不具有 在正常或高眼压眼中完全定义。 我们最近的研究表明，生长分化因子-15（GDF-15），TGF-β的远亲成员， 细胞因子超家族，是人TM细胞分泌的细胞外基质（ECM）的常规成分， 对各种IOP升高剂的反应表现出强烈的上调，并诱导细胞收缩，α- TM细胞中平滑肌肌动蛋白表达、ECM积累和SMAD活化。此外，AH 来自原发性开角型青光眼（POAG）人类患者的眼内分泌物显示出显著增加（~6倍）， 相对于来自年龄匹配的白内障受试者的对照AH样品的GDF-15水平。有趣的是，转基因 过表达人GDF-15的小鼠表现出慢性升高的IOP， 用重组rGDF-15摘除小鼠眼睛导致显著的AH流出变化。这些 有希望的和新的初步观察使我们得出结论，GDF-15在体内稳态中起着至关重要的作用。 AH流出和IOP，并假设GDF-15水平的改变破坏了参与AH流出和IOP的关键细胞事件。 AH通过TM引流，从而影响IOP并参与POAG的病因学， 被认为是全球失明的主要原因之一。 为了建立GDF-15如何调节AH流出和IOP的机制和更深入的理解， 调查将根据三个具体目标进行，以确定：1）。受体和下游 人TM细胞中GDF-15调节的信号通路和细胞特征，2）。GDF-15- 使用基因靶向和转基因小鼠和培养的器官介导的AH流出和IOP调节 人的眼睛;（3）。调节TM细胞中来自基质储存的活性GDF-15的生物利用度，以及 循环GDF-15作为青光眼患者重要生物标志物的可行性评估。 据我们所知，这是第一个深入研究GDF-15，一种应激反应细胞因子，在TM 和青光眼，其完成（基于细胞的和体内啮齿动物和人类研究）应 不仅证明了GDF-15在AH流出和IOP中的决定性作用，而且还产生了有影响力的见解 研究高眼压的病因学，并确定青光眼的创新治疗方法。

PROJECT SUMMARY Elevated intraocular pressure (IOP) caused by impaired aqueous humor (AH) drainage through the trabecular meshwork (TM) is recognized to hasten optic nerve atrophy and retinal ganglion cell death in glaucoma patients. Neither the external factors nor intracellular mechanisms regulating AH drainage through the TM have been fully defined in normal or ocular hypertensive eyes. Our recent studies revealed that Growth Differentiation Factor-15 (GDF-15), a distant member of the TGF-β superfamily of cytokines, is a regular constituent of the extracellular matrix (ECM) secreted by human TM cells, exhibits robust upregulation in response to various IOP elevating agents, and induces cellular contractility, α- smooth muscle actin expression, ECM accumulation and SMAD activation in TM cells. Furthermore, AH derived from primary open-angle glaucoma (POAG) human patients exhibited a significant increase (~6 fold) in GDF-15 levels relative to control AH samples from age-matched cataract subjects. Interestingly, transgenic mice overexpressing human GDF-15 exhibited chronically elevated IOP, and short-term perfusion of enucleated mouse eyes with recombinant rGDF-15 resulted in significant AH outflow changes. These promising and novel preliminary observations led us to conclude a crucial role for GDF-15 in homeostasis of AH outflow and IOP, and to hypothesize that alterations in GDF-15 levels disrupt key cellular events involved in AH drainage through the TM, thereby impacting IOP and participating in the etiology of POAG, which is considered one of the leading causes of blindness globally. To establish a mechanistic and deeper understanding of how GDF-15 regulates AH outflow and IOP, investigations will be carried out under three specific aims to determine: 1). The receptors and downstream signaling pathways and the cellular characteristics regulated by GDF-15 in human TM cells, 2). GDF-15- mediated regulation of AH outflow and IOP using gene targeted and transgenic mice and organ cultured human eyes, and 3). Regulation of bio-availability of active GDF-15 from stromal stores in TM cells, and feasibility assessment of circulating GDF-15 as a biomarker of significance in glaucoma patients. To the best of our knowledge, this is the first in-depth study on GDF-15, a stress response cytokine, in TM and glaucoma, the completion of which (cell-based and in vivo rodent and human studies) should demonstrate not only the definitive role of GDF-15 in AH outflow and IOP, but also generate impactful insights into the etiology of ocular hypertension and enable identification of innovative treatments for glaucoma.