Glutathione Monoesters to Counteract Ocular Chemical Injury

 描述(由申请人提供)：该项目的目标是测试谷胱甘肽单酯(GME)可用作对抗化学战剂硫芥酸(SM)引起的眼睛毒性的第一道防线的假设。这种发泡剂会导致严重的眼部损伤，包括眼皮灼伤、疼痛、长时间结膜炎、角膜混浊、角膜溃疡，严重时还会失明。氧化应激、细胞凋亡、炎症和蛋白降解是SM诱导组织损伤的已知机制之一。在细胞培养实验中，SM诱导的毒性与谷胱甘肽(GSH)的耗竭有关，补充GSH或N-乙酰半胱氨酸(NAC)可以预防和/或保护SM诱导的细胞损伤。虽然这些发现令人鼓舞，但使用GSH或NAC作为治疗方法有几个缺点，包括GSH和NAC的生物利用度有限，以及NAC作为促氧化剂的可能性。这些固有的问题大大降低了使用GSH或NAC作为治疗药物来预防SM引起的眼部损伤的潜力。我们建议测试这一假设，即GME保护眼睛免受暴露于SM造成的损害。谷胱甘肽三肽的甘氨酸羧基发生酯化反应后形成的GSH单酯，已被证明是一种有效的GSH递送剂。它们很容易被转运到细胞内，然后被细胞内酯酶酶切释放GSH。体外和体内研究表明，GME处理后细胞内总GSH水平的升高超过了单独GSH处理的结果。因此，GME避免了与单独使用GSH作为化学战剂的治疗策略相关的细胞摄取挑战。本项目的具体目标是确定GME治疗SM所致眼组织损伤的疗效。这将涉及使用一种新的体外隔离兔眼(IRE)模型来测量GME治疗对SM类似物暴露后损伤深度(DOI)的影响。这项提案中概述的实验的成功完成将提供重要的可行性数据，这些数据有望支持该项目的扩展，以检查GME对活体动物中SM的保护作用。

 DESCRIPTION (provided by applicant): The goal of this project is to test the hypothesis that glutathione monoesters (GME) can be used as a first line of defense against ocular toxicity caused by the chemical warfare agent sulfur mustard (SM). This vesicant causes severe ocular injuries, including eyelid burns, pain, prolonged conjunctivitis, corneal opacity, corneal ulceratin and, in severe cases, blindness. Oxidative stress, apoptosis, inflammation and proteolysis are among the known mechanisms involved in the pathogenesis of tissue injury induced by SM. It is well established that SM-induced toxicity is associated with depletion of glutathione (GSH) and that supplementation with either GSH or N-acetylcysteine (NAC) may prevent and/or protect against SM-induced cellular injury in cell culture experiments. While these findings are encouraging, the approach of using GSH or NAC as a treatment has several drawbacks, including the limited bioavailability of GSH and NAC as well as that the possibility of NAC acting as pro-oxidant. These inherent problems diminish substantially the potential of using either GSH or NAC as therapeutic agents for protection against ocular injury caused by SM. We propose to test the hypothesis that GME protects the eye against damage caused by exposure to SM. Monoesters of GSH, in which the glycine carboxyl group of the GSH tripeptide is esterified, have been shown to be effective GSH delivery agents. They are readily transported into cells and then enzymatically cleaved by intracellular esterases to release GSH. In vitro and in vivo studies have shown that GME treatment results in elevations in total cellular GSH levels that exceed those achieved by GSH treatment alone. Hence, GME obviates the cellular uptake challenges associated with using GSH alone as a treatment strategy for chemical warfare agents. The specific goal of this project is to determine the efficacy of GME in treating ocular tissue damage induced by SM. This will involve the use of a novel ex vivo isolated rabbit eye (IRE) model to measure the effect of GME treatment on the depth of injury (DoI) following SM analog exposure. Successful completion of the experiments outlined in this proposal will provide important feasibility data that are anticipated to support the expansion of this project to examining the protective effects of GME against SM in live animals.