Soluble epoxide hydrolase and epoxide fatty acid involvement in corneal injury after ammonia exposure: Mechanisms of injury and potential therapeutics using sEH inhibitors and biostable EpFA mimics.

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Ammonia solution (20%) (AMM) is highly toxic and of interest to the CCRP. A major target for acute ammonia exposure is the cornea. Corneal ammonia exposure results in an alkali wound, which can lead to a host of potentially blinding pathologic features and often times loss of the eye. There are few studies describing AMM cornea wounds and the mechanisms leading to those injures, with no established model to carry out such studies. We hypothesize that a significant pathway leading to pathologies associated with AMM-induced corneal alkali burn wounds is the rapid hydration of epoxy fatty acids (EpFA) by soluble epoxide hydroxylase (sEH). EpFAs are anti-inflammatory, inflammation-resolving and anti-fibrotic CYP450 metabolites of long chain polyunsaturated fatty acids. Consequently, AMM injury-induced sEH hydration of EpFAs disrupts the natural inflammation resolving and anti-fibrotic pathways present in the cornea. Moreover, we hypothesize that AMM corneal injuries can be minimized or resolved using topically applied sEH inhibitors (sEHI) and/or natural EpFAs such as EETs, including novel sEHI and EpFA mimics developed and synthesized in our labs. The long-term objectives of this project are several fold, with the overall goals being to gain a better understanding of the mechanisms behind injuries created by corneal AMM exposure, and to develop potential therapeutics to treat AMM-induced wounds. Given that AMM wounds are at least in part due to exposure to an extremely alkali agent, these therapeutics could have broad applications. The project Specific Aims are: Aim 1. Develop novel, reliable in vitro and in vivo mouse cornea AMM-injury models to test the hypothesis that sEH activity reduces EpFA concentrations following mouse cornea AMM exposure, and determine the cellular location of sEH in control corneas and in corneas following AMM injury. Aim 2. Test the hypothesis that AMM-induced corneal injuries can be diminished or resolved using topically applied sEHI and/or EpFAs. Aim 3. Quantify sEH and EpFA levels in human corneas and develop repeatable human cornea AMM-injury models to examine the effects of AMM exposure on sEH and EpFAs in cultured primary human corneal cells and ex vivo donor cornea rims. The in vivo mouse wound healing studies and cell culture models will be carried out in Dr. Watsky's lab using models currently in development, along with immunohistochemistry studies. sEH and EpFA quantitative analysis will be performed by ELISA and mass spectroscopy in Dr. Hammock's lab. Therapeutics to be tested and topically applied to AMM-wounded corneas will include sEHIs and EpFAs synthesized in Dr. Hammock's lab, and biostable EpFA mimics designed and synthesized in the labs of Drs. Hammock and Vic. Human tissue and cell culture AMM exposure model development will be carried out in Dr. Watsky's lab using donor cornea rims and cells cultured from those rims, which are routinely obtained and utilized in the lab.