Ocular mustard keratopathy elicits induced autophagy, which is detrimental to the cornea

About This Grant

PROJECT SUMMARY/ABSTRACT The long-term goal of this project is to understand the pathological mechanisms of sulfur mustard gas keratopathy (MGK) in the cornea. Sulfur mustard (SM) is an alkylating agent that has been used as a chemical warfare agent. SM exposure to the eye results in acute corneal injury. A subset of patients, particularly those with high exposure levels, develop chronic or delayed symptoms, which is known as MGK. Thus far, there are no specific treatments available to stop or reverse the detrimental effects of MGK. One of reasons for the lack of a specific treatment is that the mechanisms of MGK are not fully understood. Autophagy is a process by which cells break down and recycle their own cellular components, including damaged proteins and organelles. Even though autophagy has been recognized as a fundamental cellular process against stress, autophagy can play beneficial or detrimental roles depending on the context. In the cornea, it has been demonstrated that in response to most of stresses, autophagy plays beneficial roles to protect tissue homeostasis. Our laboratory and many other investigators have been focusing on such protective roles of autophagy in the cornea. However, the detrimental role of autophagy in the cornea has not been studied. Interestingly, when we investigated the role of autophagy in corneal injury due to chemical exposure, we found that nitrogen mustard (NM), an analog of sulfur mustard, induced a unique autophagy, which plays a harmful role in the cornea. It has been shown that the liberation of Beclin1, a key regulator in induction of autophagy, from Beclin1-Bcl2 complex can induce autophagy. Our preliminary data suggest that after NM exposure, sequestration of Beclin1 in Beclin1-Bcl2 complex attenuates NM-induced corneal inflammation. Therefore, we hypothesize that corneal mustard exposure induces autophagy via liberating Beclin1 from Beclin1-Bcl2 complex and such induced autophagy promotes corneal inflammation and contributes to MGK. In Aim 1, we will explore: (i) whether NM exposure will affect Beclin1-Bcl2 binding in vitro and in vivo; and (ii) whether manipulation of Beclin1-Bcl2 binding will affect NM-induced autophagy in cornea. In Aim 2, we will capitalize on our ability to conduct gain- and loss-of-function studies of induced autophagy in mice. We will inhibit induced autophagy via either reducing Beclin1 expression or preventing the disassociation of Beclin1-Bcl2 complex in vivo. We will also enhance induced autophagy via preventing the binding of Beclin1 to Bcl2 in vivo. We will utilize these genetically modified mouse models to determine whether the detrimental effects of NM exposure in cornea will be: (i) attenuated by inhibition of induced autophagy, while (ii) increased by enhancement of induced autophagy. Finally, in Aim3, we will test whether transient, pharmacological inhibition of autophagy attenuate NM-induced corneal injury. Knowledge from this project will reveal the pathological importance of induced autophagy in corneal MGK and will form the foundation for the development of novel therapies for this disease by targeting this Beclin1-Bcl2 complex-regulated autophagy pathway.