Identification of drugs for treatment of SM injury to eye and skin

Lovelace Biomedical & Environmental Research Institute, Albuquerque NM

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Abstract

Identification of Drugs for Treatment of SM Injury to Eye and Skin Sulfur mustard (SM), a highly reactive electrophilic alkylating agent that has cytotoxic and vesicant properties, was used extensively as a chemical warfare agent in World War I, and more recently, in the Iran-Iraq War. US intelligence agencies and the Congressional Research Service place SM as the most likely chemical agent to be used in a terror attack, due to its ease of manufacture, severe public heath risk, lack of current medical treatments and ease of dissemination. The blistering effect of SM occurs in eye and skin by a combination of SM-induced damage of epithelial cells (apoptosis and necrosis) and release of inflammatory cytokines. These processes lead to massive inflammation accompanied by edema and release of proteases that destroy the proteins attaching corneal epithelial cells to their basement membrane, ultimately leading to sloughing (blistering) of the epithelial cell layer. Importantly, until now, no post SM-exposure treatment has been proven to reduce the severity of acute injury (blistering) or to reduce long term complications (chronic skin and eye wounds that failure to heal and lung disease). In pilot experiments, we have found that the metalloprotease inhibitors, llomastat and doxycycline, dramatically reduced acute clinical symptoms and neovascularization of rabbit eyes exposed to SM vapor. In addition, llomastat totally blocked microvesication of organ cultured human skin explants exposed to SM vapor, even when given 8 hours after SM exposure. We propose to extend these initial experiments to thoroughly evaluate the ability of these metalloprotease inhibitors and other selected lead drugs (indomethacin, diclofenac, dexamethasone, n-octyl homovanillamide) to reduce acute effects of SM exposure in rabbit eyes and hairless guinea pig skin models. As part of the rigorous evaluation, we will also develop an improved method of delivering SM aerosol/vapor to eyes and skin of the test animals using the extensive experience of LRRI personnel in aerosol delivery of agents. Furthermore, in collaboration with Nanotherapeutics, Inc., to enhance the therapeutic effects of the drugs, we will develop advanced nanoparticle formulations of the test drugs which will provide sustained release of the drugs over several hours. The two drugs that most effectively reduce acute symptoms of SM exposure in the eye and skin models will be tested under cGLP conditions in Project 5 using the mini-pig skin model and rabbit ocular exposure model.