Glutathione Monoesters to Counteract Ocular Chemical Injury

 描述（由申请人提供）：本项目的目标是检验谷胱甘肽单酯（GME）可用作化学战剂硫芥（SM）引起的眼毒性的第一道防线的假设。这种起疱剂会导致严重的眼部损伤，包括眼睑灼伤、疼痛、长期结膜炎、角膜混浊、角膜溃疡，严重者会导致失明。氧化应激、细胞凋亡、炎症和蛋白水解是SM诱导的组织损伤的发病机制之一。已经确定SM诱导的毒性与谷胱甘肽（GSH）耗竭相关，补充GSH或N-乙酰半胱氨酸（NAC）可在细胞培养实验中预防和/或保护SM诱导的细胞损伤。虽然这些发现是令人鼓舞的，但使用GSH或NAC作为治疗的方法有几个缺点，包括GSH和NAC的有限生物利用度以及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作为治疗剂来保护免受SM引起的眼损伤的潜力。我们建议测试的假设，即GME保护眼睛免受损害暴露于SM。GSH的单酯，其中GSH三肽的甘氨酸羧基被酯化，已被证明是有效的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解释放GSH。体外和体内研究表明，GME治疗导致总细胞GSH水平升高，超过单独GSH治疗所达到的水平。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在治疗SM诱导的眼组织损伤中的疗效。这将涉及使用新的离体离体兔眼（IRE）模型来测量SM类似物暴露后GME治疗对损伤深度（DoI）的影响。成功完成本提案中概述的实验将提供重要的可行性数据，预计这些数据将支持将本项目扩展到研究转基因生物对活体动物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.