Trabecular Meshwork Cytoskeletal Signaling-Regulation of Aqueous Humor Outflow

描述（由申请人提供）：原发性开角型青光眼（POAG）是美国致盲的第二大原因，通常与眼内压（IOP）升高有关，这是由于房水（AH）通过小梁网（TM）和施莱姆管（SC）流出的阻力增加所致。虽然IOP被认为是开角型青光眼的主要危险因素，但其对AH流出物抵抗力增加的病因机制在很大程度上尚不清楚。该应用的长期目标是确定通过TM和SC增加AH流出抵抗力的具体病因机制，并利用这一知识开发降低青光眼患者IOP的新型靶向疗法。我们最近开发了一种动物模型，该模型显示，在AH流出通路中，组成型活性Rho GTPase （RhoAV14）的表达会导致IOP持续增加。基于从该模型中获得的非常重要和有希望的初步观察结果，我们提出了一个新的假设，即小梁流出通道中Rho/Rho激酶信号活性异常引起的高眼压与TM和SC细胞向基质生成肌成纤维样细胞的内皮细胞向间充质细胞转变的增强机制相关。其激活导致细胞外基质（ECM）沉积和导管旁结缔组织（JCT）结构改变，导致对AH流出的阻力增加。我们在rhoav14诱导的眼高血压大鼠眼和人类POAG供体眼的小梁通路中发现JCT瘢痕、ECM积累和肌成纤维细胞特异性标记物的表达支持了这一中心假设。我们建议从三个具体目标来研究这一新的假设：1。确定Rho/Rho激酶信号在机械应变和与青光眼相关的生理相关因子（TGF-¿、autotaxin/LPA轴、结缔组织生长因子）作用下，在驱动TM和SC细胞内皮细胞向间充质转化（EndMT）为基质生成肌成纤维细胞样细胞中的作用；2. 2 .验证RhoAV14大鼠模型中高眼压、TM和SC细胞向肌成纤维样细胞的EndMT增加、AH流出通道组织结构改变和AH流出阻力增加之间的机制联系；以RhoAV14眼高压大鼠为模型系统，评估Rho激酶抑制剂在高眼压青光眼中增加AH流出的功效部分与抑制ECM沉积和活化的肌成纤维细胞在AH流出通路中的成纤维作用有关。这些研究的探索有望确定青光眼患者AH流出抵抗性增加的具体病因机制，并增强我们对某些生理因素和Rho激酶抑制剂如何影响青光眼患者AH流出和IOP的机制理解。

DESCRIPTION (provided by applicant): Primary open-angle glaucoma (POAG) is the second leading cause of blindness in the United States and is commonly associated with elevation of intraocular pressure (IOP) resulting from increased resistance to aqueous humor (AH) outflow through the trabecular meshwork (TM) and Schlemm's canal (SC). Although IOP is considered to be a primary risk factor for open angle glaucoma, the etiological mechanisms responsible for increased resistance to AH outflow are largely unknown. The long-range goal of this application is to identify specific etiological mechanisms underlying increased resistance to AH outflow through the TM and SC, and leverage this knowledge to develop novel and targeted therapies for lowering IOP in glaucoma patients. We recently developed an animal model that exhibits a sustained increase in IOP in response to expression of a constitutively active Rho GTPase (RhoAV14) in the AH outflow pathway. Based on the highly significant and promising preliminary observations derived from this model, we propose a novel hypothesis that ocular hypertension induced by aberrant Rho/Rho kinase signaling activity in the trabecular outflow pathway is mechanistically linked to an enhanced endothelial to mesenchymal transition of TM and SC cells into matrix producing myofibroblast-like cells, the activation of which results in extracellular matrix (ECM) deposition and changes in juxtacanalicular connective tissue (JCT) architecture, leading to increased resistance to AH outflow. This central hypothesis is supported by our findings of scarring of the JCT, ECM accumulation and expression of myofibroblast-specific markers in the trabecular pathway of RhoAV14-induced ocular hypertensive rat eyes and in human POAG donor eyes. We propose to investigate this novel hypothesis under three specific aims: 1. Establish the role of Rho/Rho kinase signaling in driving the endothelial to mesenchymal transition (EndMT) of TM and SC cells into matrix-producing myofibroblast-like cells, upon exposure to mechanical strain and physiologically relevant factors (TGF-¿, autotaxin/LPA axis, connective tissue growth factor) associated with glaucoma; 2. Verify the mechanistic link between ocular hypertension in the RhoAV14 rat model, increased EndMT of TM and SC cells into myofibroblast-like cells, structural alterations within AH outflow pathway tissues, and increased resistance to AH outflow, and 3. Evaluate the validity of the prediction that the efficacy of Rho kinase inhibitors to increase AH outflow in ocular hypertensive glaucomatous eyes is linked partly to suppression of ECM deposition and fibrogenic effects of activated myofibroblasts in AH outflow pathway, using the RhoAV14 ocular hypertensive rat as a model system. Exploration of these studies is expected to identify the specific etiological mechanisms involved in increased resistance to AH outflow in glaucoma subjects and enhance our mechanistic understanding of how certain physiological factors and Rho kinase inhibitors influence AH outflow and IOP in glaucoma patients.