Targeting ER Stress Pathway Using Sodium 4-Phenylbutyrate for the Treatment of POAG

摘要 原发性开角型青光眼(POAG)是导致不可逆性失明的主要原因，通常与 小梁房水流出阻力增加引起的眼压升高 网络(TM)。导致青光眼TM损害和眼压升高的病理机制是 人们对此知之甚少。我们之前已经将蛋白质错误折叠和内质网(ER)应激与 青光眼TM损害和眼压升高的发生。重要的是，我们证明了 小分子化学伴侣4-苯丁酸钠(PBA)引起的肌红素异常积聚和内质网应激 救治占全身青光眼4%的霉素性青光眼小鼠模型。我们的长期目标是 目的：确定PBA能否用于治疗普适性青光眼。增加积累 由于降解的基质金属蛋白酶(MMPs)活性降低而导致细胞外基质(ECM)的减少 细胞外ECM参与了全身性POAG的病理生理过程。我们最近证明了 在POAG的TM中，ECM积聚增加导致慢性内质网应激。此外，我们的初步研究 提示PBA通过诱导和激活MMPs来减少ECM的积聚。这是我们的中心前提 ECM积聚增加导致慢性内质网应激，导致TM功能障碍和眼压升高 POAG和PBA通过诱导和激活MMPs减少细胞外基质堆积和内质网应激。为了测试这一点 假设，我们将利用原代人类TM细胞和糖皮质激素(GC)或转化生长因子β2诱导的小鼠模型 高眼压和人灌流培养的POAG眼。已知GC或转化生长因子β2都参与了 青光眼流出阻力增加和细胞外基质增加引起的TM损害的病理生理学研究 在TM中的积累。根据我们的初步数据，GC激活转化生长因子β2信号，我们将研究 转化生长因子β-2信号对糖皮质激素诱导的青光眼的调控作用考虑到转化生长因子β-2在血管生成中的主要作用 POAG的发病机制，接下来我们将确定转化生长因子β2是否诱导慢性内质网应激，导致TM 通过基因敲除慢性内质网应激的关键介质而导致的功能障碍和眼压升高(目标2)。在《目标3》中， 我们将确定苯巴比妥钠是否改善流出功能和预防转化生长因子β2诱导的高眼压。 小鼠和体外人灌流培养眼。我们还将确定PBA是否能降低高眼压 通过其非伴侣活性诱导和激活MMPs。拟议的研究将提供 TM功能障碍的病理机制及其通过PBA治疗全身疾病的靶向 普阿格。重要的是，这些研究将为计划中的PBA临床试验提供重要的基础 爱荷华大学。

Abstract Primary open angle glaucoma (POAG), a major cause of irreversible blindness, is often associated with elevated intraocular pressure (IOP) due to increased aqueous humor outflow resistance at the trabecular meshwork (TM). The pathological mechanisms leading to glaucomatous TM damage and IOP elevation are poorly understood. We have previously linked protein misfolding and endoplasmic reticulum (ER) stress to development of glaucomatous TM damage and IOP elevation. Importantly, we demonstrated that targeting abnormal myocilin accumulation and ER stress via small chemical chaperone, sodium 4-phenylbutyrate (PBA) rescues mouse model of myocilin glaucoma, which accounts for ~4% of general POAG. Our long-term goal is to determine whether PBA can be used for the treatment of the general POAG cases. Increased accumulation of extracellular matrix (ECM) due to reduced activity of matrix metalloproteinases (MMPs) that degrade extracellular ECM is implicated in the pathophysiology of general POAG. We have recently demonstrated that increased ECM accumulation induces chronic ER stress in the TM of POAG. Moreover, our preliminary studies suggest that PBA reduces ECM accumulation via induction and activation of MMPs. It is our central premise that increased ECM accumulation induces chronic ER stress, leading to TM dysfunction and IOP elevation in POAG and PBA reduces ECM accumulation and ER stress via induction and activation of MMPs. To test this hypothesis, we will utilize primary human TM cells and mouse models of glucocorticoid (GC) or TGFβ2-induced ocular hypertension and human perfusion cultured POAG eyes. Both GC or TGFβ2 are known to be involved in the pathophysiology of glaucomatous TM damage via increased outflow resistance and increased ECM accumulation in the TM. Based on our preliminary data that GCs activate TGFβ2 signaling, we will examine whether TGFβ2 signaling regulates GC-induced glaucoma (Aim1). Considering the major role of TGFβ2 in the pathogenesis of POAG, we will next determine whether TGFβ2 induces chronic ER stress, leading to TM dysfunction and IOP elevation via genetic knockdown of key mediators of chronic ER stress (Aim 2). In Aim 3, we will determine whether PBA improves outflow facility and prevents TGFβ2-induced ocular hypertension in mice and ex-vivo human perfusion cultured eyes. We will also determine whether PBA reduces elevated IOP via its non-chaperonin activity on induction and activation of MMPs. The proposed studies will provide pathological mechanisms of TM dysfunction and target these pathologies via PBA for the treatment of general POAG. Importantly, these studies will provide an important foundation for planned clinical trials for PBA at the University of Iowa.